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2007 Volume 24 Issue 11
2007, 24(11): 1225-1231
Abstract:
This review focuses on summarizing the development of catalyst types, catalytic cracking proce-ssings, influencing factors and mechanisms of the catalytic cracking of C4/C5 hydrocabons to light olefins. ZSM-5 Zeolite has been taken as the primary catalysts and used in C4/C5 hydrocabons catalytic cracking to light olefins. On the basis of ZSM-5 zeolite, the acid-modified or high-silica hydrothermally promoted ZSM-5 series, and the mesopore zeolite MCM-41 have been developed. In addition, the catalytic cracking processings of C4/C5 hydrocarbons have been covered. The primary factors of catalytic cracking are thought to be the components of cracking feed, the kinds of catalysts and processing conditions. The mechanism of the combination of carbonium ion with free-radical is proposed for the process of catalytic cracking. The major research futures and results on the catalytic cracking of C4 alkanes of our research laboratory are briefly introduced.
This review focuses on summarizing the development of catalyst types, catalytic cracking proce-ssings, influencing factors and mechanisms of the catalytic cracking of C4/C5 hydrocabons to light olefins. ZSM-5 Zeolite has been taken as the primary catalysts and used in C4/C5 hydrocabons catalytic cracking to light olefins. On the basis of ZSM-5 zeolite, the acid-modified or high-silica hydrothermally promoted ZSM-5 series, and the mesopore zeolite MCM-41 have been developed. In addition, the catalytic cracking processings of C4/C5 hydrocarbons have been covered. The primary factors of catalytic cracking are thought to be the components of cracking feed, the kinds of catalysts and processing conditions. The mechanism of the combination of carbonium ion with free-radical is proposed for the process of catalytic cracking. The major research futures and results on the catalytic cracking of C4 alkanes of our research laboratory are briefly introduced.
2007, 24(11): 1232-1235
Abstract:
Active carbon supported myoglobin(Mb-C) catalyst was prepared via the balance adsorption method. The cyclic voltammetric measurements indicated that the redox peaks of Mb adsorbed on the active carbon were located at -342 and -402 mV, respectively. The currents of the redox peaks are basically equal. The peak currents were proportional to the scan rate. These results indicated that Mb adsorbed on the active carbon and underwent a non-diffused, direct and quasi-reversible electrochemical reaction. The stability of the Mb-C catalyst fixed on the glassy carbon(GC) electrode by Nafion membrane was excellent. The cyclic voltammogram of the Mb-C/GC electrode immersed in the phosphate buffer solution for 7 days was similar to that measured immediately after preparation. The amount of Mb adsorbed on the electrode was calculated to be 4.5×10-10 mol/cm2. In addition, the Mb-C catalyst showed a good electrocatalytic activity for the reduction of O2, illustrating that the Mb adsorbed on the active carbon was not denatured and thus its bioactivity was maintained. Thus, the Mb-C catalyst can be used as the cathodic catalyst in the biofuel cell.
Active carbon supported myoglobin(Mb-C) catalyst was prepared via the balance adsorption method. The cyclic voltammetric measurements indicated that the redox peaks of Mb adsorbed on the active carbon were located at -342 and -402 mV, respectively. The currents of the redox peaks are basically equal. The peak currents were proportional to the scan rate. These results indicated that Mb adsorbed on the active carbon and underwent a non-diffused, direct and quasi-reversible electrochemical reaction. The stability of the Mb-C catalyst fixed on the glassy carbon(GC) electrode by Nafion membrane was excellent. The cyclic voltammogram of the Mb-C/GC electrode immersed in the phosphate buffer solution for 7 days was similar to that measured immediately after preparation. The amount of Mb adsorbed on the electrode was calculated to be 4.5×10-10 mol/cm2. In addition, the Mb-C catalyst showed a good electrocatalytic activity for the reduction of O2, illustrating that the Mb adsorbed on the active carbon was not denatured and thus its bioactivity was maintained. Thus, the Mb-C catalyst can be used as the cathodic catalyst in the biofuel cell.
2007, 24(11): 1236-1239
Abstract:
Silane coupling agent KH570 was hydrolyzed in alcohol with acid solution as a catalyst. Then nanoalumina was modified with it by wet surface modification. The rate of coverage of the coupling agent was determined by roasting method. The hydrolysis conditions of KH570 and their influence on the coupling effect were investigated. It was found that the hydrolysis conditions such as the acid used had important influence on the coupling, and the proper hydrolysis conditions of the silane coupling agent were: oxalic acid as the catalyst, pH 3~4, hydrolysis at room temperature for 1 h. The proper processing conditions for the surface modifier for nano-alumina were that the mass percent of coupling agent was 4.5%, at 45℃ reacting for 5.5 h. It was shown by IR that the silane coupling agent reacted with the surface —OH of the alumina, by which nano-alumina was modified. Both the dispersity and stability of the modified alumina in organic phase were improved.
Silane coupling agent KH570 was hydrolyzed in alcohol with acid solution as a catalyst. Then nanoalumina was modified with it by wet surface modification. The rate of coverage of the coupling agent was determined by roasting method. The hydrolysis conditions of KH570 and their influence on the coupling effect were investigated. It was found that the hydrolysis conditions such as the acid used had important influence on the coupling, and the proper hydrolysis conditions of the silane coupling agent were: oxalic acid as the catalyst, pH 3~4, hydrolysis at room temperature for 1 h. The proper processing conditions for the surface modifier for nano-alumina were that the mass percent of coupling agent was 4.5%, at 45℃ reacting for 5.5 h. It was shown by IR that the silane coupling agent reacted with the surface —OH of the alumina, by which nano-alumina was modified. Both the dispersity and stability of the modified alumina in organic phase were improved.
2007, 24(11): 1240-1244
Abstract:
Zirconium hydroxide was produced by digestion of hydrous oxide at 100℃ with the control of reflux time. The structural information, surface area and thermal stability were characterized by means of XRD, TG-DTG, chemical analysis and N2 adsorption-desorption techniques. The zirconium hydroxide obtained by digestion can be used to prepare SO42-/Al2O3/ZrO2 solid acid and the catalytic activities of these materials were examined in n-butane isomerization. The data show the crystallization and the transformation from the metastable tetragonal phase to the monoclinic phase were retarded with digestion during calcination. However, the hydroxyl of hydrous zirconia decreased with long time digestion which showed a passive effect on retaining surface sulfated and catalytic activity. With digestion time increasing, the thermal stability and surface area increased while the sulfated content was not monotonically increasing. The results show the sulfated content of catalyst was less than 1.1% after 96 h digestion and its n-butane conversion was no more than 20%. In contrast, the sulfated content of the catalyst was 1.45% after 24 h digestion refluxing. The n-butane conversion on the resulting catalyst was more than 46%, which is close to the equilibrium conversion of n-butane.
Zirconium hydroxide was produced by digestion of hydrous oxide at 100℃ with the control of reflux time. The structural information, surface area and thermal stability were characterized by means of XRD, TG-DTG, chemical analysis and N2 adsorption-desorption techniques. The zirconium hydroxide obtained by digestion can be used to prepare SO42-/Al2O3/ZrO2 solid acid and the catalytic activities of these materials were examined in n-butane isomerization. The data show the crystallization and the transformation from the metastable tetragonal phase to the monoclinic phase were retarded with digestion during calcination. However, the hydroxyl of hydrous zirconia decreased with long time digestion which showed a passive effect on retaining surface sulfated and catalytic activity. With digestion time increasing, the thermal stability and surface area increased while the sulfated content was not monotonically increasing. The results show the sulfated content of catalyst was less than 1.1% after 96 h digestion and its n-butane conversion was no more than 20%. In contrast, the sulfated content of the catalyst was 1.45% after 24 h digestion refluxing. The n-butane conversion on the resulting catalyst was more than 46%, which is close to the equilibrium conversion of n-butane.
2007, 24(11): 1245-1249
Abstract:
Capsaicinoids was isolated and purified by 40% ethanol extraction, followed by macroporous adsorption resin column chromatography with 70% ethanol as elutent from extract of Capsicum frutescens L.. The concentration of ethanol, isolated capsaicinoids from pigment primarily, was studied. A solution contained capsaicinoids 0.42 g/L was obtained by extraction separation with 40% ethanol from the extract of Capsicum frutescens L. with a recovery ratio of 78%. A macroporous adsorption resin was selected as the medium for the purification of capsaicinoids after comparing static adsorption and elution performances of 11 kinds of macroporous adsorption resin and its static adsorption capacity was 26.1 mg/g. Further investigation of dynamic adsorption and elution behavior indicated that resin D01 had the capability of selective adsorption of capsaicinoids from the extract of Capsicum frutescens L. with 16.0 mg/g of dynamic adsorption capacity. The capsaicinoids, by extraction separation with 40% ethanol from the extract of Capsicum frutescens L. and then macroporous adsorption resin column chromatography with 70% ethanol as elutent, was enriched from 1.5% to 81.7% as determinated by HPLC, with a recovery ratio of 78.3%. It is simple and useful and meets the demands of green chemistry.
Capsaicinoids was isolated and purified by 40% ethanol extraction, followed by macroporous adsorption resin column chromatography with 70% ethanol as elutent from extract of Capsicum frutescens L.. The concentration of ethanol, isolated capsaicinoids from pigment primarily, was studied. A solution contained capsaicinoids 0.42 g/L was obtained by extraction separation with 40% ethanol from the extract of Capsicum frutescens L. with a recovery ratio of 78%. A macroporous adsorption resin was selected as the medium for the purification of capsaicinoids after comparing static adsorption and elution performances of 11 kinds of macroporous adsorption resin and its static adsorption capacity was 26.1 mg/g. Further investigation of dynamic adsorption and elution behavior indicated that resin D01 had the capability of selective adsorption of capsaicinoids from the extract of Capsicum frutescens L. with 16.0 mg/g of dynamic adsorption capacity. The capsaicinoids, by extraction separation with 40% ethanol from the extract of Capsicum frutescens L. and then macroporous adsorption resin column chromatography with 70% ethanol as elutent, was enriched from 1.5% to 81.7% as determinated by HPLC, with a recovery ratio of 78.3%. It is simple and useful and meets the demands of green chemistry.
2007, 24(11): 1250-1254
Abstract:
The interaction between DNA and polyamine(PA) with different valency was studied via phase diagram. The influence of NaCl on the interaction between spermine(SPM) and DNA was also studied primarily. The result shows that there was electrostatic attraction between SPM and DNA, and interaction between SPM and DNA base pair as well. The SPM-DNA syetem began to show turbidity at a low SPM concentration(0.025 mmol/L), while the turbidities of spermidine(SPD)-DNA and guanidine hydrochloride(GD)-DNA systems didn't change much. With the increasing of polyamine, the A260 of the SPD-DNA system reduced while the A260 of the GD-DNA system didn't change much when the concentration of polyamine was 10 mmol/L, showing the interaction between SPD and DNA was stronger than that of GD-DNA system. So the higher the valeny of the polyamine, the stronger the interaction of the system. In aqueous solution, interactions between DNA and SPD or GD were weaker, and no phase separation was observed. After the addition of NaCl, the interaction between SPM and DNA will be baffled because of electrostatic-screening effect. The higher the NaCl concentration, the weaker the interaction and the worse the linearity of the phase curve of the system.
The interaction between DNA and polyamine(PA) with different valency was studied via phase diagram. The influence of NaCl on the interaction between spermine(SPM) and DNA was also studied primarily. The result shows that there was electrostatic attraction between SPM and DNA, and interaction between SPM and DNA base pair as well. The SPM-DNA syetem began to show turbidity at a low SPM concentration(0.025 mmol/L), while the turbidities of spermidine(SPD)-DNA and guanidine hydrochloride(GD)-DNA systems didn't change much. With the increasing of polyamine, the A260 of the SPD-DNA system reduced while the A260 of the GD-DNA system didn't change much when the concentration of polyamine was 10 mmol/L, showing the interaction between SPD and DNA was stronger than that of GD-DNA system. So the higher the valeny of the polyamine, the stronger the interaction of the system. In aqueous solution, interactions between DNA and SPD or GD were weaker, and no phase separation was observed. After the addition of NaCl, the interaction between SPM and DNA will be baffled because of electrostatic-screening effect. The higher the NaCl concentration, the weaker the interaction and the worse the linearity of the phase curve of the system.
2007, 24(11): 1255-1258
Abstract:
A novel low toxicity caprolactam-cation-based Bronsted acid ionic liquid(IL) was prepared and used as the solvent and catalyst in the nitration of toluene with 1 equiv of 67% nitric acid. The structure of the ionic liquid was characterized by 1H NMR and FTIR. The effect of reaction temperature, reaction time and the amount of catalyst on product yield and para-selectivity for the nitration of toluene was investigated. Nitroto-luene with a yield of 37.1% and an ortho-para isomer ratio of 1.2 was obtained under the optimal conditions. The ionic liquid was recycled 4 times with a slightly decreased yield and the same para-selectivity. The structure of the reused ionic liquid was characterized by MS, and it was found that the IL was stable under the reaction conditions.
A novel low toxicity caprolactam-cation-based Bronsted acid ionic liquid(IL) was prepared and used as the solvent and catalyst in the nitration of toluene with 1 equiv of 67% nitric acid. The structure of the ionic liquid was characterized by 1H NMR and FTIR. The effect of reaction temperature, reaction time and the amount of catalyst on product yield and para-selectivity for the nitration of toluene was investigated. Nitroto-luene with a yield of 37.1% and an ortho-para isomer ratio of 1.2 was obtained under the optimal conditions. The ionic liquid was recycled 4 times with a slightly decreased yield and the same para-selectivity. The structure of the reused ionic liquid was characterized by MS, and it was found that the IL was stable under the reaction conditions.
2007, 24(11): 1259-1262
Abstract:
Surface-modified nanocrystalline anatase titania with different morphologies were prepared via a non-hydrolytic route through a simplified supercritical CO2 method, which deploys direct sealing of dry ice into autoclave instead of using supercritical CO2. The decomposition of Ti(OC4H9)4 precursor was fulfilled at 190℃ with the presence of oleyamine as surfactant in toluene and CO2. The pressure inside the autoclave could reach 17 MPa due to the evaporation of dry ice at elevated temperature. The morphologies and structure of the products were characterized by XRD, TEM and FT-IR. The experimental results show that the products obtained using surfactant are dispersible within organic solvents such as toluene and hexane. Nanorods of titania with dimension size of 2×8 nm could be obtained when the volume ration of tolune:oleyamine:Ti(OC4H9)4 was set as 2:0.4:0.5. The growth direction of such nanorods might be along with the C axis of anatase titania. A possible growth mechanism and function of dry ice in this system were proposed based on experimental observations.
Surface-modified nanocrystalline anatase titania with different morphologies were prepared via a non-hydrolytic route through a simplified supercritical CO2 method, which deploys direct sealing of dry ice into autoclave instead of using supercritical CO2. The decomposition of Ti(OC4H9)4 precursor was fulfilled at 190℃ with the presence of oleyamine as surfactant in toluene and CO2. The pressure inside the autoclave could reach 17 MPa due to the evaporation of dry ice at elevated temperature. The morphologies and structure of the products were characterized by XRD, TEM and FT-IR. The experimental results show that the products obtained using surfactant are dispersible within organic solvents such as toluene and hexane. Nanorods of titania with dimension size of 2×8 nm could be obtained when the volume ration of tolune:oleyamine:Ti(OC4H9)4 was set as 2:0.4:0.5. The growth direction of such nanorods might be along with the C axis of anatase titania. A possible growth mechanism and function of dry ice in this system were proposed based on experimental observations.
2007, 24(11): 1263-1267
Abstract:
An novel organic silane, 3,3',3"-trihydroxyltriphenoxy silane triglycidyl ether was synthesized. Curing behavior of the organic silane and modified bisphenol F epoxy was studied. The modifier has a lower reaction velocity than bisphenol F epoxy. The curing temperature range of organic silane containing 2% 2,4-Limidazol is 20℃ narrower than that of bisphenol F epoxy. Activation energy of 2,4-limidazol/organic silane/bisphenol F epoxy system was calculated to be 50.53 kJ/mol by Kissinge method, lower than that of unmodified bisphenol F system(66.68 kJ/mol). The frequency factor is lower also, which results in a lower velocity constant. The modified bisphenol F epoxy has a narrower curing temperature range, indicating that it can be cured more effectively. 3,3',3"-Trihydroxyltriphenoxy silane triglycidyl ether can improve the properties of the cured epoxy resin, the thermal expansion coefficient below Tg is reduced by 18.8%, the internal stress is decreased by 22.8% and the crack resistance index is increased by 52.2%. Meanwhile, Tg temperature is hardly decreased
An novel organic silane, 3,3',3"-trihydroxyltriphenoxy silane triglycidyl ether was synthesized. Curing behavior of the organic silane and modified bisphenol F epoxy was studied. The modifier has a lower reaction velocity than bisphenol F epoxy. The curing temperature range of organic silane containing 2% 2,4-Limidazol is 20℃ narrower than that of bisphenol F epoxy. Activation energy of 2,4-limidazol/organic silane/bisphenol F epoxy system was calculated to be 50.53 kJ/mol by Kissinge method, lower than that of unmodified bisphenol F system(66.68 kJ/mol). The frequency factor is lower also, which results in a lower velocity constant. The modified bisphenol F epoxy has a narrower curing temperature range, indicating that it can be cured more effectively. 3,3',3"-Trihydroxyltriphenoxy silane triglycidyl ether can improve the properties of the cured epoxy resin, the thermal expansion coefficient below Tg is reduced by 18.8%, the internal stress is decreased by 22.8% and the crack resistance index is increased by 52.2%. Meanwhile, Tg temperature is hardly decreased
2007, 24(11): 1268-1272
Abstract:
Three tetraorganodistannoxanes containing silicon were synthesized and their catalytic properties in esterification and acetalization were observed via the reactions of acetic acid with isoamyl alcohol and butyraldehyde with glycol. The factors affecting the reaction, such as the catalyst dosage, reaction time and solvent kind, etc. were discussed. The results show that three tetraorganodistannoxanes displayed similar good catalytic activities compared to dichlorotetrabutyldistannoxane in the esterification and acetalization. When the dosage of [ClBu2SnOSn(CH2SiMe3)2Cl]2 was 1.5% based on the mass of the reactant, the yield of isoamyl acetate was 91.8%, and the yield of butyraldehyde glycol acetal 94.2%. The different alkyl and bridging groups on Sn sites in the structure of the tetraorganodistannoxanes showed influences, to a certain extent, on the catalytic activities of these compounds.
Three tetraorganodistannoxanes containing silicon were synthesized and their catalytic properties in esterification and acetalization were observed via the reactions of acetic acid with isoamyl alcohol and butyraldehyde with glycol. The factors affecting the reaction, such as the catalyst dosage, reaction time and solvent kind, etc. were discussed. The results show that three tetraorganodistannoxanes displayed similar good catalytic activities compared to dichlorotetrabutyldistannoxane in the esterification and acetalization. When the dosage of [ClBu2SnOSn(CH2SiMe3)2Cl]2 was 1.5% based on the mass of the reactant, the yield of isoamyl acetate was 91.8%, and the yield of butyraldehyde glycol acetal 94.2%. The different alkyl and bridging groups on Sn sites in the structure of the tetraorganodistannoxanes showed influences, to a certain extent, on the catalytic activities of these compounds.
2007, 24(11): 1273-1278
Abstract:
Six new 1-ferrocenesulfonyl-2-benzimidazole derivatives were prepared from the reaction of ferrocenesulfonylchloride with benzimidazole derivatives in the presence of dichloromethane and n-tetrabutylammonia chloride. The yields of six new ferrocenesulfonyl benzimidazole derivatives were about 80%. The structures were confirmed by IR, 1H NMR, elemental analysis and MS. Its crystal structure was determined via X-ray single crystal diffraction. The title compound a2 belongs to the monoclinic system with space group C2/c, and the unit cell parameters are a=2.825 2(2) nm, b=0.976 96(7) nm, c=1.648 28(12) nm, α=90°, β=92.053(2)°, γ=90°, V=4.546 6(6) nm3, Z=8, F(000)=2 024, Mr=481.40, Dc=1.407 g/cm3, μ=0.784 mm-3, R1=0.049 5, wR2=0.151 7. The results show that the reactions of 2-alkylbenzimidazoles with ferrocenesulfonyl chloride give 1-ferrocenesulfonyl-2-alkylbenzimidazoles in good yields.
Six new 1-ferrocenesulfonyl-2-benzimidazole derivatives were prepared from the reaction of ferrocenesulfonylchloride with benzimidazole derivatives in the presence of dichloromethane and n-tetrabutylammonia chloride. The yields of six new ferrocenesulfonyl benzimidazole derivatives were about 80%. The structures were confirmed by IR, 1H NMR, elemental analysis and MS. Its crystal structure was determined via X-ray single crystal diffraction. The title compound a2 belongs to the monoclinic system with space group C2/c, and the unit cell parameters are a=2.825 2(2) nm, b=0.976 96(7) nm, c=1.648 28(12) nm, α=90°, β=92.053(2)°, γ=90°, V=4.546 6(6) nm3, Z=8, F(000)=2 024, Mr=481.40, Dc=1.407 g/cm3, μ=0.784 mm-3, R1=0.049 5, wR2=0.151 7. The results show that the reactions of 2-alkylbenzimidazoles with ferrocenesulfonyl chloride give 1-ferrocenesulfonyl-2-alkylbenzimidazoles in good yields.
2007, 24(11): 1279-1283
Abstract:
An acid was used as the catalyst to adjust the hydrolysis rate of TiCl4, and a high active nanosize TiO2 photocatalyst was obtained by means of acid catalyzed hydrolysis method. Various preparation parameters such as the kind of acid catalysts, hydrolysis temperature and calcination temperature were optimized by means of phenol degradation. XRD, DRS, SEM and N2 adsorption isotherm were used for the characterization of TiO2 photocatalyst. The optimal preparation conditions were determined as: catalyst:HCl, hydrolysis reaction temperature:98℃, and calcination temperature:500℃. The prepared TiO2 precursor was uncrystalline. With the increasing of calcination temperature, uncrystalline was transformed into anatase, accompanyed with the threshold red-shift, SBET decreased and particle size increased. Completely transformation of anatase to rutile can be realized at 800℃.
An acid was used as the catalyst to adjust the hydrolysis rate of TiCl4, and a high active nanosize TiO2 photocatalyst was obtained by means of acid catalyzed hydrolysis method. Various preparation parameters such as the kind of acid catalysts, hydrolysis temperature and calcination temperature were optimized by means of phenol degradation. XRD, DRS, SEM and N2 adsorption isotherm were used for the characterization of TiO2 photocatalyst. The optimal preparation conditions were determined as: catalyst:HCl, hydrolysis reaction temperature:98℃, and calcination temperature:500℃. The prepared TiO2 precursor was uncrystalline. With the increasing of calcination temperature, uncrystalline was transformed into anatase, accompanyed with the threshold red-shift, SBET decreased and particle size increased. Completely transformation of anatase to rutile can be realized at 800℃.
2007, 24(11): 1284-1288
Abstract:
Five new N-(4,6-disubstituted pyrimidin-2-yl)-N'-(1-methyl-3-ethyl-4-chloropyrazol-5-yl)formylurea compounds and five new N-(4,6-disubstituted pyrimidin-2-yl)-N'-(1-methyl-3-ethyl-4-chloropyrazol-5-yl)formylthiourea compounds were synthesized with 1-methyl-3-ethyl-4-chloropyrazol-5-yl formic acid and 2-amino-4,6-disubstituted pyrimidine as raw materials. The structures of the title compounds were characterized by IR, 1H NMR and elemental analysis. The preliminary bioassay tests show that they have not satisfying acaricidal activity, but some of them have herbicidal activity to some extent. For example, the inhibition rate of compounds Ⅰb, Ⅰc and Ⅰe against Barnyard grass at a dosage of 50 mg/L are 61%, 61% and 67%, respectively.
Five new N-(4,6-disubstituted pyrimidin-2-yl)-N'-(1-methyl-3-ethyl-4-chloropyrazol-5-yl)formylurea compounds and five new N-(4,6-disubstituted pyrimidin-2-yl)-N'-(1-methyl-3-ethyl-4-chloropyrazol-5-yl)formylthiourea compounds were synthesized with 1-methyl-3-ethyl-4-chloropyrazol-5-yl formic acid and 2-amino-4,6-disubstituted pyrimidine as raw materials. The structures of the title compounds were characterized by IR, 1H NMR and elemental analysis. The preliminary bioassay tests show that they have not satisfying acaricidal activity, but some of them have herbicidal activity to some extent. For example, the inhibition rate of compounds Ⅰb, Ⅰc and Ⅰe against Barnyard grass at a dosage of 50 mg/L are 61%, 61% and 67%, respectively.
2007, 24(11): 1289-1294
Abstract:
A two-step swelling procedure was adopted to synthesize mono-dispersed and high cross-linked poly(styrene-divinylbenzene) particles with polystyrene micro-spheres(1.80 μm in diam), which were prepared by a dispersion polymerization method and used as seeds. The effects of monomer concentration, the ratio of ethanol to water, swelling agents, crosslinking agents, swelling temperature and agitation speed to particle size were discussed in detail. The morphologies and size distributions of these micro-spheres were examined by SEM and PSA. The Tg of the micro-spheres was tested by DSC. The results indicate that the particles(6.20 μm in diam) exhibited excellent mono-dispersed property and high crosslinking degree when the conditions were that the concentration of the swelling agent and crosslinking agent was 25% and 23%, the swelling temperature was 30℃, and the stirring speed was 150 r/min.
A two-step swelling procedure was adopted to synthesize mono-dispersed and high cross-linked poly(styrene-divinylbenzene) particles with polystyrene micro-spheres(1.80 μm in diam), which were prepared by a dispersion polymerization method and used as seeds. The effects of monomer concentration, the ratio of ethanol to water, swelling agents, crosslinking agents, swelling temperature and agitation speed to particle size were discussed in detail. The morphologies and size distributions of these micro-spheres were examined by SEM and PSA. The Tg of the micro-spheres was tested by DSC. The results indicate that the particles(6.20 μm in diam) exhibited excellent mono-dispersed property and high crosslinking degree when the conditions were that the concentration of the swelling agent and crosslinking agent was 25% and 23%, the swelling temperature was 30℃, and the stirring speed was 150 r/min.
2007, 24(11): 1295-1298
Abstract:
1,3-Di[5-(3-propoxy)phenyl-10,15,20-tri(3-chlorophenyl)porphyrin]-5-fluorouracil(A1), 1-[5-(3-propoxy)phenyl-10,15,20-tri(3-chlorophenyl)porphyrin]-5-fluorouracil(B1), 1,3-di[5-(3-butoxy)phenyl-10,15,20-tri(3-chlorophenyl)porphyrin]-5-fluorouracil(A2) and 1-[5-(3-butoxy)phenyl-10,15,20-tri(3-chlorophenyl)porphyrin]-5-fluorouracil(B2) were synthesized from 5-[3-(3-bromo-propoxy)phenyl]-10,15,20-tri(3-chlorophenyl)porphyrin or 5-[3-(4-bromo-butoxy)phenyl]-10,15,20-tri(3-chlorophenyl)porphyrin and 5-fluorouracil in yield of 20.4%, 12.3%, 21.4%, and 11.4%, respectively.Their structures were characterized by UV-Vis, IR, 1H NMR and MALDI-TOF-MS. The synthesis and separation conditions of the target compounds were studied. The results show that the yield was higher when DMF was used as the solvent at 120℃ for 10 h. The products were separated via column chromatography with silica gel(40 μm). The separation was more satisfactory with chloroform-acetone(V:V=15:1) as the eluent when the column was 3 cm in diameter and 10 cm in hight.
1,3-Di[5-(3-propoxy)phenyl-10,15,20-tri(3-chlorophenyl)porphyrin]-5-fluorouracil(A1), 1-[5-(3-propoxy)phenyl-10,15,20-tri(3-chlorophenyl)porphyrin]-5-fluorouracil(B1), 1,3-di[5-(3-butoxy)phenyl-10,15,20-tri(3-chlorophenyl)porphyrin]-5-fluorouracil(A2) and 1-[5-(3-butoxy)phenyl-10,15,20-tri(3-chlorophenyl)porphyrin]-5-fluorouracil(B2) were synthesized from 5-[3-(3-bromo-propoxy)phenyl]-10,15,20-tri(3-chlorophenyl)porphyrin or 5-[3-(4-bromo-butoxy)phenyl]-10,15,20-tri(3-chlorophenyl)porphyrin and 5-fluorouracil in yield of 20.4%, 12.3%, 21.4%, and 11.4%, respectively.Their structures were characterized by UV-Vis, IR, 1H NMR and MALDI-TOF-MS. The synthesis and separation conditions of the target compounds were studied. The results show that the yield was higher when DMF was used as the solvent at 120℃ for 10 h. The products were separated via column chromatography with silica gel(40 μm). The separation was more satisfactory with chloroform-acetone(V:V=15:1) as the eluent when the column was 3 cm in diameter and 10 cm in hight.
2007, 24(11): 1299-1303
Abstract:
The heteropoly siliconmolybdate nanoparticles modified with 2-octathio-5-mercapto-1,3,4-thiodiazole Ag(Ⅰ) were prepared in a solution of water-ethanol. The shape, composition and structure of the nanoparticles were characterized by means of transmission electron microscope(TEM), scanning electron microscope(SEM), Fourier transform infrared spectrometer(FT-IR) and thermal analyzer(TG-DTA). In addition, the tribological properties were investigated with a four-ball tribometer. The result shows that the nanoparticles obtained disperse in organic solvents very well. They also have a Keggin structure with the mean graininess diameter about 20 nm. The decomposition temperature is between 220~370℃. As a new-type lube additive, when the load is 300 N, the reaction time is 30 min and the rotation speed is 1 450 r/min, the best additive mass fraction is 0.05%, with the tribological spot decreased by 43.4% and the friction coefficient decreased by 23.6%.
The heteropoly siliconmolybdate nanoparticles modified with 2-octathio-5-mercapto-1,3,4-thiodiazole Ag(Ⅰ) were prepared in a solution of water-ethanol. The shape, composition and structure of the nanoparticles were characterized by means of transmission electron microscope(TEM), scanning electron microscope(SEM), Fourier transform infrared spectrometer(FT-IR) and thermal analyzer(TG-DTA). In addition, the tribological properties were investigated with a four-ball tribometer. The result shows that the nanoparticles obtained disperse in organic solvents very well. They also have a Keggin structure with the mean graininess diameter about 20 nm. The decomposition temperature is between 220~370℃. As a new-type lube additive, when the load is 300 N, the reaction time is 30 min and the rotation speed is 1 450 r/min, the best additive mass fraction is 0.05%, with the tribological spot decreased by 43.4% and the friction coefficient decreased by 23.6%.
2007, 24(11): 1304-1309
Abstract:
Cu-Zn-Ti catalysts were prepared by means of coprecipitation method. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, temperature programmed reduction, and H2 adsorption. The catalytic performance of the Cu-Zn-Ti catalysts for the gas phase hydrogenation of maleic anhydride in the presence of n-butanol was studied at 235~280℃ and 1 MPa. The conversion of maleic anhydride was more than 96% and the selectivity of tetrahydrofuran was up to 92.7%. At the same time, n-butanol was converted to hydrogen and butyl butyrate via dehydrogenation, disproportionation, and esterfication. There were two kinds of CuO species present in the calcined Cu-Zn-Ti catalysts. At a lower copper content, the CuO interacted with ZnO and TiO2; at a higher copper content, both the surface-anchored and bulk CuO species were present. Metallic copper(Cu0) produced by the reduction of the CuO species, which strongly interacted with ZnO and TiO2, favored the deep hydrogenation of maleic anhydride. The deep hydrogenation ability of the Cu-Zn-Ti catalyst increased with the increase of lattice distortion of Cu0.
Cu-Zn-Ti catalysts were prepared by means of coprecipitation method. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, temperature programmed reduction, and H2 adsorption. The catalytic performance of the Cu-Zn-Ti catalysts for the gas phase hydrogenation of maleic anhydride in the presence of n-butanol was studied at 235~280℃ and 1 MPa. The conversion of maleic anhydride was more than 96% and the selectivity of tetrahydrofuran was up to 92.7%. At the same time, n-butanol was converted to hydrogen and butyl butyrate via dehydrogenation, disproportionation, and esterfication. There were two kinds of CuO species present in the calcined Cu-Zn-Ti catalysts. At a lower copper content, the CuO interacted with ZnO and TiO2; at a higher copper content, both the surface-anchored and bulk CuO species were present. Metallic copper(Cu0) produced by the reduction of the CuO species, which strongly interacted with ZnO and TiO2, favored the deep hydrogenation of maleic anhydride. The deep hydrogenation ability of the Cu-Zn-Ti catalyst increased with the increase of lattice distortion of Cu0.
2007, 24(11): 1310-1313
Abstract:
The optimized synthesis route and process conditions of Sitaxsentan sodium were reported. 4-Methyl-pyrocatechol(1) reacted with dichloromethane(2) to give 5-methy 1-benzparallel[d][1,3]dioxolene(3), then chloromethylated into 5-chloromethyl-6-methyl-benzparallel[d][1,3]dioxolene(5), compound 5 reacted with magnesium(6) to obtain Grignard reagent(7). Sitaxsentan(9) was obtained through the reaction of N-methoxyl-N-methyl-3-[(4-chloro-3-methyl-5-isoxazole)-sulfamido]-2-thenylamide(Weinreb amide)(8) with Grignard reagent 7 in the presence of an acid, and Sitaxsentan sodium(10) was finally obtained from saturated dicarbonate solution. The structure of the product was proved by nuclear magnetic resonance analysis. The overall yield of compound 9 is 52.6%, and that of compound 10 is 54.2%. The optimal temperature of synthesizing compound 3 is 100℃ and tetrabutylammonium chloride accelerates the synthesis reaction of compound 3 as catalyst.The by-product was not obtained by using tetrabutylammonium chloride in place of tetrabutylammonium bromide as catalyst of synthesizing compound 5. The reaction time was reduced and the cost was decreased by changing the molar ratio of raw material and reaction order when compounds 9 and 10 were synthesized.
The optimized synthesis route and process conditions of Sitaxsentan sodium were reported. 4-Methyl-pyrocatechol(1) reacted with dichloromethane(2) to give 5-methy 1-benzparallel[d][1,3]dioxolene(3), then chloromethylated into 5-chloromethyl-6-methyl-benzparallel[d][1,3]dioxolene(5), compound 5 reacted with magnesium(6) to obtain Grignard reagent(7). Sitaxsentan(9) was obtained through the reaction of N-methoxyl-N-methyl-3-[(4-chloro-3-methyl-5-isoxazole)-sulfamido]-2-thenylamide(Weinreb amide)(8) with Grignard reagent 7 in the presence of an acid, and Sitaxsentan sodium(10) was finally obtained from saturated dicarbonate solution. The structure of the product was proved by nuclear magnetic resonance analysis. The overall yield of compound 9 is 52.6%, and that of compound 10 is 54.2%. The optimal temperature of synthesizing compound 3 is 100℃ and tetrabutylammonium chloride accelerates the synthesis reaction of compound 3 as catalyst.The by-product was not obtained by using tetrabutylammonium chloride in place of tetrabutylammonium bromide as catalyst of synthesizing compound 5. The reaction time was reduced and the cost was decreased by changing the molar ratio of raw material and reaction order when compounds 9 and 10 were synthesized.
2007, 24(11): 1314-1317
Abstract:
A novel phosphorus, nitrogen and sulfur containing fire retardant, N,N'-bis(2-thio-5,5-dimethyl-1,3,2-dioxaphosphorinane) ethane(DDPSN) was synthesized by reacting neopentyl glycol with thiophosphoryl chloride to get 2-thio-2-chloro-5,5-dimethyl-1,3,2-dioxaphosphorinane(DDSP), which was then reacted with ethylenediamine. The title compound was characterized by elemental analysis, IR, 1H NMR and MS. The thermal properties of the title compound were researched by TG, and the factors that influence the yield of DDPSN, such as molar ratio, acid acceptor, reaction temperature, were also studied. The results show that the structure of the product was consistent with what we anticipated. The initial thermal decomposition temperature was over 290℃, and at 1 000℃, there was 24.5% char residue left, indicating that the title compound has a good thermal stability and a char forming capability. The yield of DDSP was 85% when the molar ratio of neopentyl glycol to thiophosphoryl chloride was 1.75:1, and the yield of DDPSN was 89% when the molar ratio of DDSP to ethylenediamine was 1:1.25. 4-Dimethylaminopyridine(DMAP) was a better acid acceptor than pyridine and triethylamine, and when the mass amount of DMAP was 1% that of neopentyl glycol, the yield of DDPSN was up to 92%. The optimal reaction temperature was 0~5℃. The fire retarded viscose film with 18% DDPSN exhibited a limited oxygen index(LOI) of 28%, indicating that DDPSN is a fire retardant with good char forming capability. The scanning electron micrographs(SEM) of the char produced from burnt fire retarded viscose film showed that the surface of the char had many lump pulp, and the section of the char had honeycomb structure, which indicated that the fire retardant is intumescent.
A novel phosphorus, nitrogen and sulfur containing fire retardant, N,N'-bis(2-thio-5,5-dimethyl-1,3,2-dioxaphosphorinane) ethane(DDPSN) was synthesized by reacting neopentyl glycol with thiophosphoryl chloride to get 2-thio-2-chloro-5,5-dimethyl-1,3,2-dioxaphosphorinane(DDSP), which was then reacted with ethylenediamine. The title compound was characterized by elemental analysis, IR, 1H NMR and MS. The thermal properties of the title compound were researched by TG, and the factors that influence the yield of DDPSN, such as molar ratio, acid acceptor, reaction temperature, were also studied. The results show that the structure of the product was consistent with what we anticipated. The initial thermal decomposition temperature was over 290℃, and at 1 000℃, there was 24.5% char residue left, indicating that the title compound has a good thermal stability and a char forming capability. The yield of DDSP was 85% when the molar ratio of neopentyl glycol to thiophosphoryl chloride was 1.75:1, and the yield of DDPSN was 89% when the molar ratio of DDSP to ethylenediamine was 1:1.25. 4-Dimethylaminopyridine(DMAP) was a better acid acceptor than pyridine and triethylamine, and when the mass amount of DMAP was 1% that of neopentyl glycol, the yield of DDPSN was up to 92%. The optimal reaction temperature was 0~5℃. The fire retarded viscose film with 18% DDPSN exhibited a limited oxygen index(LOI) of 28%, indicating that DDPSN is a fire retardant with good char forming capability. The scanning electron micrographs(SEM) of the char produced from burnt fire retarded viscose film showed that the surface of the char had many lump pulp, and the section of the char had honeycomb structure, which indicated that the fire retardant is intumescent.
2007, 24(11): 1318-1321
Abstract:
Styrene-divinyl benzene copolymer and polyurea resin were used to encapsulate a phase change material by free radical polymerization and interfacial polymerization. The shell structure and the thermal properties of the microcapsule were investigated using fourier transform infrared spectroscopy(FT-IR), differential scanning calorimetry(DSC) and themogravimetry(TG). The encapsulation efficiency was intestigated by means of solvent drip washing. The influence of different parameters such as the amount of monomer, core-to-coating ratio and the content of emulsifier on the encapsulation efficiency was investigated. The experiment results showed that the microcapsule was a kind of composite phase change material, which was compact and impermeable. When the core-to-coating ratio was 3.2(mass ratio), the emulsifier content 2%(mass ratio), the amount of styrene-divinyl benzene 6.0%, the encapsulation efficiency was up to 81.14%. The microcapsule can withstand a high temperature up to 150℃. The melt point of the phase change material was not changed and the heat associacted with the phase transition was up to 80 J/g. The energy capacity depended upon the core-to-coating ratio, and the greater the core-to-coating ratio the higher the heat capacity. It can be used to store energy.
Styrene-divinyl benzene copolymer and polyurea resin were used to encapsulate a phase change material by free radical polymerization and interfacial polymerization. The shell structure and the thermal properties of the microcapsule were investigated using fourier transform infrared spectroscopy(FT-IR), differential scanning calorimetry(DSC) and themogravimetry(TG). The encapsulation efficiency was intestigated by means of solvent drip washing. The influence of different parameters such as the amount of monomer, core-to-coating ratio and the content of emulsifier on the encapsulation efficiency was investigated. The experiment results showed that the microcapsule was a kind of composite phase change material, which was compact and impermeable. When the core-to-coating ratio was 3.2(mass ratio), the emulsifier content 2%(mass ratio), the amount of styrene-divinyl benzene 6.0%, the encapsulation efficiency was up to 81.14%. The microcapsule can withstand a high temperature up to 150℃. The melt point of the phase change material was not changed and the heat associacted with the phase transition was up to 80 J/g. The energy capacity depended upon the core-to-coating ratio, and the greater the core-to-coating ratio the higher the heat capacity. It can be used to store energy.
2007, 24(11): 1322-1326
Abstract:
Macroporous crosslinked poly(N-p-vinylbenzyldimethylamine) resin was synthesized from chloromethylated poly(styrene-co-divinylbenzene) with dimethylamine. The residual chlorine in the title resin was 0.24 mmol/g, and its weak basic exchange capacity was 4.0 mmol/g, indicating that the reaction was performed successfully. Adsorption isotherm of phenol onto the title resin from aqueous solution was measured and described with Freundlich isotherm equation with the correlation coefficients greater than 0.99. Isosteric adsorption enthalpies were determined to be -20.81~-30.74 kJ/mol when the adsorption capacities were 15, 20, and 25 mg/g, implying that hydrogen bonding was one of the driving forces for the adsorption. Gibbs adsorption energies and adsorption entropies were both less than 0, which revealed that the adsorption was a spontaneous process leading to higher order. In addition, adsorption of phenol, p-nitrophenol, and p-nitroto-luene onto the resin from aqueous solution as well as that of phenol onto the resin from aqueous, cyclohexane, ethanol, and ethyl acetate solutions were discussed, and the adsorption mechanism via the cooperation between hydrophobic interaction and hydrogen bonding was confirmed.
Macroporous crosslinked poly(N-p-vinylbenzyldimethylamine) resin was synthesized from chloromethylated poly(styrene-co-divinylbenzene) with dimethylamine. The residual chlorine in the title resin was 0.24 mmol/g, and its weak basic exchange capacity was 4.0 mmol/g, indicating that the reaction was performed successfully. Adsorption isotherm of phenol onto the title resin from aqueous solution was measured and described with Freundlich isotherm equation with the correlation coefficients greater than 0.99. Isosteric adsorption enthalpies were determined to be -20.81~-30.74 kJ/mol when the adsorption capacities were 15, 20, and 25 mg/g, implying that hydrogen bonding was one of the driving forces for the adsorption. Gibbs adsorption energies and adsorption entropies were both less than 0, which revealed that the adsorption was a spontaneous process leading to higher order. In addition, adsorption of phenol, p-nitrophenol, and p-nitroto-luene onto the resin from aqueous solution as well as that of phenol onto the resin from aqueous, cyclohexane, ethanol, and ethyl acetate solutions were discussed, and the adsorption mechanism via the cooperation between hydrophobic interaction and hydrogen bonding was confirmed.
2007, 24(11): 1327-1331
Abstract:
Reaction of 2,2,6,6-tetramethylpiperidin-4-ol-N-oxyl(TEMPO) with 2-chloroacetyl chloride gave 4-chloroacetoxy-2,2,6,6-tetramethylpiperidine-N-oxyl. An ionic-liquid immobilized TEMPO(TEMPO-IL) was then obtained via the quaternization of 1-methyl-1H-imidazole with 4-chloroacetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl followed by ion exchange with KPF6. A selective and mild ionic-liquid immobilized TEMPO/CuCl catalyzed oxidation procedure of alcohols to the corresponding aldehydes and ketones with molecular oxygen in ionic liquid [bmim]PF6 was developed. Oxidation reactions of benzylic and allylic alcohols were completed in about 10 hours at 65℃ with a conversion of 99% and 80%~90% product yields. Oxidation reactions of aliphatic and heterocyclic alcohols were more difficult with low conversion and yield. The reaction was highly product-selective and in any case only aldehyde or ketone was formed. No carboxylic acid was detected. The solvent and catalyst were easily recovered and reused in the reaction. In the case of the oxidation of benzyl alcohol, the solvent and catalyst were recovered and reused for 6 times with no decreases of benzyl alcohol conversion and product yield.
Reaction of 2,2,6,6-tetramethylpiperidin-4-ol-N-oxyl(TEMPO) with 2-chloroacetyl chloride gave 4-chloroacetoxy-2,2,6,6-tetramethylpiperidine-N-oxyl. An ionic-liquid immobilized TEMPO(TEMPO-IL) was then obtained via the quaternization of 1-methyl-1H-imidazole with 4-chloroacetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl followed by ion exchange with KPF6. A selective and mild ionic-liquid immobilized TEMPO/CuCl catalyzed oxidation procedure of alcohols to the corresponding aldehydes and ketones with molecular oxygen in ionic liquid [bmim]PF6 was developed. Oxidation reactions of benzylic and allylic alcohols were completed in about 10 hours at 65℃ with a conversion of 99% and 80%~90% product yields. Oxidation reactions of aliphatic and heterocyclic alcohols were more difficult with low conversion and yield. The reaction was highly product-selective and in any case only aldehyde or ketone was formed. No carboxylic acid was detected. The solvent and catalyst were easily recovered and reused in the reaction. In the case of the oxidation of benzyl alcohol, the solvent and catalyst were recovered and reused for 6 times with no decreases of benzyl alcohol conversion and product yield.
2007, 24(11): 1332-1336
Abstract:
The title compounds were synthesized from 3-(4'-pyridyl)/phenyl-4-amino-5-mercapto-1,2,4-triazoles with aryl acid via cyclization in the presence of phosphoryl chloride. Yields were about 42%~72%. The structure of these compounds were comfirmed by IR, 1H NMR and elemental analysis. The electro-chemical analysis was carried out at -1.4~1.0 V with negative scanning. Cyclic voltammetric curves of compounds 2a~2i showed that title compounds all had reduction peaks and their onset potentials were -0.35~-0.95 V. UV spectra and cyclic voltammograms of these compounds were measured and used to calculate their electron affinities(EA), ionization potentials(PI) and band gaps. Data show that these compounds all had higher EA(3.79~4.39 eV)and higher PI(6.95~7.84 eV) compared with PBD, which are apt to the transfer of electrons and back holes.
The title compounds were synthesized from 3-(4'-pyridyl)/phenyl-4-amino-5-mercapto-1,2,4-triazoles with aryl acid via cyclization in the presence of phosphoryl chloride. Yields were about 42%~72%. The structure of these compounds were comfirmed by IR, 1H NMR and elemental analysis. The electro-chemical analysis was carried out at -1.4~1.0 V with negative scanning. Cyclic voltammetric curves of compounds 2a~2i showed that title compounds all had reduction peaks and their onset potentials were -0.35~-0.95 V. UV spectra and cyclic voltammograms of these compounds were measured and used to calculate their electron affinities(EA), ionization potentials(PI) and band gaps. Data show that these compounds all had higher EA(3.79~4.39 eV)and higher PI(6.95~7.84 eV) compared with PBD, which are apt to the transfer of electrons and back holes.
2007, 24(11): 1337-1339
Abstract:
In a HAc-NaAc buffer solution of pH=5.2, the light scattering signals of barium and sodium tetraphenylboron at 287 nm could be enhanced obviously in the presence of polyethylene glycol 600, and on the basis of this, a sensitive and simple method is presented here to provide a way to detect trace amount of barium. The enhanced light scattering signals were proportional to the concentration of Ba2+ in the range of 3.00×10-8~3.43×10-6 g/mL, and the limit of detection was 2.80×10-9 g/mL. Additionally, the recovery of trace amount of barium in the synthetic samples was between 97.8% and 103.6%.
In a HAc-NaAc buffer solution of pH=5.2, the light scattering signals of barium and sodium tetraphenylboron at 287 nm could be enhanced obviously in the presence of polyethylene glycol 600, and on the basis of this, a sensitive and simple method is presented here to provide a way to detect trace amount of barium. The enhanced light scattering signals were proportional to the concentration of Ba2+ in the range of 3.00×10-8~3.43×10-6 g/mL, and the limit of detection was 2.80×10-9 g/mL. Additionally, the recovery of trace amount of barium in the synthetic samples was between 97.8% and 103.6%.
2007, 24(11): 1340-1342
Abstract:
A method was established for the determination of trace Cr in different cosmetic substrates by inductively coupled plasma-mass spectroscopy(ICP-MS). The sample was prepared by microwave digesting in HNO3-H2O2. Comparison research on the dosage of digesting reagent for five different cosmetic substrates was carried out. The working parameters of ICP-MS were optimized, and the matrix effect and the mass interferences were inspected; 52Cr and 53Cr were selected as the target isotopes, 72Ge as the internal standard element, and the influence due to matrix effect were compensated effectively. The experiments showed that the analysis results based on 52Cr and 53Cr was not obvious different, which satisfies the determination of Cr in cosmetics. Standard reference samples were analyzed, with the Cr concentration range of 0.1~100 μg/L. The correlation coefficient was 0.999 9, and with 0.5 mg/kg Cr doped, the average rate of recovery was around 85.3%~104%. The relative standard deviations(RSD) were 1.5%~7.3%, the detection limit of 52Cr 0.052 μg/kg, and the detection limit of 53Cr 0.036 μg/kg.
A method was established for the determination of trace Cr in different cosmetic substrates by inductively coupled plasma-mass spectroscopy(ICP-MS). The sample was prepared by microwave digesting in HNO3-H2O2. Comparison research on the dosage of digesting reagent for five different cosmetic substrates was carried out. The working parameters of ICP-MS were optimized, and the matrix effect and the mass interferences were inspected; 52Cr and 53Cr were selected as the target isotopes, 72Ge as the internal standard element, and the influence due to matrix effect were compensated effectively. The experiments showed that the analysis results based on 52Cr and 53Cr was not obvious different, which satisfies the determination of Cr in cosmetics. Standard reference samples were analyzed, with the Cr concentration range of 0.1~100 μg/L. The correlation coefficient was 0.999 9, and with 0.5 mg/kg Cr doped, the average rate of recovery was around 85.3%~104%. The relative standard deviations(RSD) were 1.5%~7.3%, the detection limit of 52Cr 0.052 μg/kg, and the detection limit of 53Cr 0.036 μg/kg.
2007, 24(11): 1343-1345
Abstract:
A separation method for Metalaxyl enantiomers by capillary electrophoresis with conductive detection was developed. The effect of running buffer, pH, the concentration of the chiral selector β-CD, separation voltage and injection time were discussed in detail. Under the following separation conditions: uncoated fused silica capillary(45 cm×75 μm) as separation channel, 5 mmol/L Na2B4O7.H2O-2 mmol/L H3BO3-4 mmol/L β-CD(pH=9.0) as running buffer, and 15 kV separation voltage, linear correlation was found between the peak height(y) and the mass concentration of R-Metalaxyl(x) in the range of 5.0~120.0 mg/L, with the regression equation y=6.1+24.3xA, and the correlation coefficient was 0.998 2, and the determination limit was 1.5 mg/L; linear correlation was found between the peak height and the mass concentration of S-Metalaxyl(x) in the range of 10.0~150.0 mg/L, with the regression equation y=4.1+18.9x, and the correlation coefficient was 0.998 6, and the determination limit was 5.0 mg/L.
A separation method for Metalaxyl enantiomers by capillary electrophoresis with conductive detection was developed. The effect of running buffer, pH, the concentration of the chiral selector β-CD, separation voltage and injection time were discussed in detail. Under the following separation conditions: uncoated fused silica capillary(45 cm×75 μm) as separation channel, 5 mmol/L Na2B4O7.H2O-2 mmol/L H3BO3-4 mmol/L β-CD(pH=9.0) as running buffer, and 15 kV separation voltage, linear correlation was found between the peak height(y) and the mass concentration of R-Metalaxyl(x) in the range of 5.0~120.0 mg/L, with the regression equation y=6.1+24.3xA, and the correlation coefficient was 0.998 2, and the determination limit was 1.5 mg/L; linear correlation was found between the peak height and the mass concentration of S-Metalaxyl(x) in the range of 10.0~150.0 mg/L, with the regression equation y=4.1+18.9x, and the correlation coefficient was 0.998 6, and the determination limit was 5.0 mg/L.
2007, 24(11): 1346-1348
Abstract:
The impurities in medical HFC-134a were qualitatively analyzed by GC-MS on HP-PLOT Al2O3S capillary column. GC-FID was used to quantitatively analyze the micro-impurities. The detection limits of the impurities were lower than 7.0×10-7 g/L, and the relative standard deviations were lower than 5.3%; the recovery rates were from 89.7% to 107.5%, and the linear correlation was obsenved in a range of 1×10-6~1×10-1 g/L, and the linear correlation coefficients were greater than 0.999 0. In the experiment, eight impurities were determined in medical HFC-134a, and the concentrations of the micro-impurities were found to be 1.22 μg/L for HFC-143a, 116.1 μg/L for HCFC-1122, 2.73 μg/L for CFC-114, 3.21 μg/L for HFC-125, 2.80 μg/L for HCFC-124, 4.99 μg/L for HFC-134 and 278.6 μg/L for HCFC-133a, respectively, but the concentration of HCFC-1122a was out of the quantitative limit. The method is simple, fast and applicable to the routine qualitative analysis of medical HFC-134a.
The impurities in medical HFC-134a were qualitatively analyzed by GC-MS on HP-PLOT Al2O3S capillary column. GC-FID was used to quantitatively analyze the micro-impurities. The detection limits of the impurities were lower than 7.0×10-7 g/L, and the relative standard deviations were lower than 5.3%; the recovery rates were from 89.7% to 107.5%, and the linear correlation was obsenved in a range of 1×10-6~1×10-1 g/L, and the linear correlation coefficients were greater than 0.999 0. In the experiment, eight impurities were determined in medical HFC-134a, and the concentrations of the micro-impurities were found to be 1.22 μg/L for HFC-143a, 116.1 μg/L for HCFC-1122, 2.73 μg/L for CFC-114, 3.21 μg/L for HFC-125, 2.80 μg/L for HCFC-124, 4.99 μg/L for HFC-134 and 278.6 μg/L for HCFC-133a, respectively, but the concentration of HCFC-1122a was out of the quantitative limit. The method is simple, fast and applicable to the routine qualitative analysis of medical HFC-134a.
