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2014 Volume 32 Issue 9
2014, 32(9): 905-905
doi: 10.3724/SP.J.1123.2014.08016
Abstract:
2014, 32(9): 906-912
doi: 10.3724/SP.J.1123.2014.07045
Abstract:
The determination of organic composition in atmospheric particulate matter (PM) is of great importance in understanding how PM affects human health, environment, climate, and ecosystem. Organic components are also the scientific basis for emission source tracking, PM regulation and risk management. Therefore, the molecular characterization of the organic fraction of PM has become one of the priority research issues in the field of environmental analysis. Due to the extreme complexity of PM samples, chromatographic methods have been the chief selection. The common procedure for the analysis of organic components in PM includes several steps: sample collection on the fiber filters, sample preparation (transform the sample into a form suitable for chromatographic analysis), analysis by chromatographic methods. Among these steps, the sample preparation methods will largely determine the throughput and the data quality. Solvent extraction methods followed by sample pretreatment (e. g. pre-separation, derivatization, pre-concentration) have long been used for PM sample analysis, and thermal desorption methods have also mainly focused on the non-polar organic component analysis in PM. In this paper, the sample preparation methods prior to chromatographic analysis of organic components in PM are reviewed comprehensively, and the corresponding merits and limitations of each method are also briefly discussed.
The determination of organic composition in atmospheric particulate matter (PM) is of great importance in understanding how PM affects human health, environment, climate, and ecosystem. Organic components are also the scientific basis for emission source tracking, PM regulation and risk management. Therefore, the molecular characterization of the organic fraction of PM has become one of the priority research issues in the field of environmental analysis. Due to the extreme complexity of PM samples, chromatographic methods have been the chief selection. The common procedure for the analysis of organic components in PM includes several steps: sample collection on the fiber filters, sample preparation (transform the sample into a form suitable for chromatographic analysis), analysis by chromatographic methods. Among these steps, the sample preparation methods will largely determine the throughput and the data quality. Solvent extraction methods followed by sample pretreatment (e. g. pre-separation, derivatization, pre-concentration) have long been used for PM sample analysis, and thermal desorption methods have also mainly focused on the non-polar organic component analysis in PM. In this paper, the sample preparation methods prior to chromatographic analysis of organic components in PM are reviewed comprehensively, and the corresponding merits and limitations of each method are also briefly discussed.
2014, 32(9): 913-918
doi: 10.3724/SP.J.1123.2014.05029
Abstract:
A novel dispersive liquid-liquid microextraction method based on solidification of floating organic droplets (DLLME-SFO) technique was developed for the determination of seven benzotriazole ultraviolet (UV) stabilizers in seawater samples by high performance liquid chromatography with tandem mass spectrometry. The optimal liquid-liquid microextraction experiment conditions were as follows: 20 μL of 1-dodecanol as extraction solvent, 400 μL of methanol as dispersive solvent, 8% (mass percentage) NaCl, pH of the sample below 6, vortex oscillation extraction time in 2 min. The separation of target compounds was achieved by combining a Hypersil GOLD analytical column (150 mm×2.1 mm, 5 μm) with methanol-water as mobile phase with gradient elution program. Quantitative determination by ESI-MS/MS was achieved using positive ion mode with multiple reaction monitoring mode. The proposed method showed good linearity with the correlation coefficients all above 0.99. The blank samples were spiked at three levels and the average recoveries of target compounds ranged from 68.3% to 127.5% with the RSDs from 0.9% to 15.2%. The limits of detection (LODs) and limits of quantification (LOQs) of the method for the seven target compounds were in the ranges of 0.001-0.090 μg/L and 0.003-0.300 μg/L, respectively. The developed method was successfully applied for the analysis of the UV stabilizers in seawater at Dalian seashores, and some of the benzotriazoles were detected. The method is simple, rapid, environment friendly, highly sensitive and suitable for rapid analysis of benzotriazole UV stabilizers in seawater.
A novel dispersive liquid-liquid microextraction method based on solidification of floating organic droplets (DLLME-SFO) technique was developed for the determination of seven benzotriazole ultraviolet (UV) stabilizers in seawater samples by high performance liquid chromatography with tandem mass spectrometry. The optimal liquid-liquid microextraction experiment conditions were as follows: 20 μL of 1-dodecanol as extraction solvent, 400 μL of methanol as dispersive solvent, 8% (mass percentage) NaCl, pH of the sample below 6, vortex oscillation extraction time in 2 min. The separation of target compounds was achieved by combining a Hypersil GOLD analytical column (150 mm×2.1 mm, 5 μm) with methanol-water as mobile phase with gradient elution program. Quantitative determination by ESI-MS/MS was achieved using positive ion mode with multiple reaction monitoring mode. The proposed method showed good linearity with the correlation coefficients all above 0.99. The blank samples were spiked at three levels and the average recoveries of target compounds ranged from 68.3% to 127.5% with the RSDs from 0.9% to 15.2%. The limits of detection (LODs) and limits of quantification (LOQs) of the method for the seven target compounds were in the ranges of 0.001-0.090 μg/L and 0.003-0.300 μg/L, respectively. The developed method was successfully applied for the analysis of the UV stabilizers in seawater at Dalian seashores, and some of the benzotriazoles were detected. The method is simple, rapid, environment friendly, highly sensitive and suitable for rapid analysis of benzotriazole UV stabilizers in seawater.
2014, 32(9): 919-925
doi: 10.3724/SP.J.1123.2014.05024
Abstract:
A solid phase extraction (SPE)-ultrahigh pressure liquid chromatography (UPLC) method coupled with tandem mass spectrometry was developed for the simultaneous analysis of the 14 short- and long-chain perfluorinated compounds (PFCs) in water. Water sample was concentrated and purified through WAX mixed-mode SPE cartridges. The separation of PFCs was performed on a BEH C18 column with gradient elution using methanol-5 mmol/L ammonium acetate as mobile phases. The PFCs were quantified by internal standard method in multiple-reaction monitoring mode. The calibration curves of the 14 PFCs were linear in the range of 0.1-50 μg/L with the correlation coefficients > 0.99. The limits of detection (S/N=3) and quantitation (S/N=10) of the method were 0.09-1.15 ng/L and 0.29-3.85 ng/L, respectively. The average recoveries of eight PFCs at three spiked levels of 2, 10 and 20 ng/L were 85.0%, 120.2% and 117.4%, with the relative standard deviations of 9.2%, 9.0% and 6.6%, respectively. The recoveries of the rest six PFCs were low due to unavoidable strong adsorption on the bottle/tube walls during sample pretreatment. The method was applied in the determination of PFCs in real samples of a lake in South China. Four short-chain and five long-chain PFCs were detected with mass concentrations of 41.29-49.05 ng/L and 98.43-111.02 ng/L, respectively. The results show that the method is suitable for the simultaneous analysis of short- and long-chain perfluorinated compounds in environmental water.
A solid phase extraction (SPE)-ultrahigh pressure liquid chromatography (UPLC) method coupled with tandem mass spectrometry was developed for the simultaneous analysis of the 14 short- and long-chain perfluorinated compounds (PFCs) in water. Water sample was concentrated and purified through WAX mixed-mode SPE cartridges. The separation of PFCs was performed on a BEH C18 column with gradient elution using methanol-5 mmol/L ammonium acetate as mobile phases. The PFCs were quantified by internal standard method in multiple-reaction monitoring mode. The calibration curves of the 14 PFCs were linear in the range of 0.1-50 μg/L with the correlation coefficients > 0.99. The limits of detection (S/N=3) and quantitation (S/N=10) of the method were 0.09-1.15 ng/L and 0.29-3.85 ng/L, respectively. The average recoveries of eight PFCs at three spiked levels of 2, 10 and 20 ng/L were 85.0%, 120.2% and 117.4%, with the relative standard deviations of 9.2%, 9.0% and 6.6%, respectively. The recoveries of the rest six PFCs were low due to unavoidable strong adsorption on the bottle/tube walls during sample pretreatment. The method was applied in the determination of PFCs in real samples of a lake in South China. Four short-chain and five long-chain PFCs were detected with mass concentrations of 41.29-49.05 ng/L and 98.43-111.02 ng/L, respectively. The results show that the method is suitable for the simultaneous analysis of short- and long-chain perfluorinated compounds in environmental water.
2014, 32(9): 926-929
doi: 10.3724/SP.J.1123.2014.05025
Abstract:
A fast analytical method for the determination of aniline in water and fish meat by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. The water sample was mixed with acetonitrile by 4:1 (v/v) and the fish sample was extracted by 2.00 mL acetonitrile for each gram of sample, and then the extracts of water and fish samples were centrifuged at 5000 r/min for 5 min. The separation was performed on a reversed-phase Cl8 column using mobile phases of acetonitrile-0.5%(v/v) formic acid aqueous solution (85:15, v/v). Aniline was separated within 3 min. The calibration curve was linear in the range of 0.5-500 μg/L with R2>0.999. The limits of detection (LODs) were 0.50 μg/L and 1.00 μg/kg and the limits of quantification (LOQs) were 1.00 μg/L and 2.00 μg/kg for aniline in water and fish meat, respectively. The average recoveries of aniline in water were 93.7% at the spiked level of 40 ng and 86.7% at the spiked level of 400 ng (n=5). The average recoveries of aniline in fish were 96.8%, 92.6% and 81.8% at the spiked levels of 5, 50 and 500 ng respectively (n=5). The relative standard deviations were 1.5%-9.2%. Thirteen water samples and twelve fish samples were collected from a reservoir polluted by aniline and the maximum contents found were 1943.6 μg/L in water and 60.8 μg/kg in fish. The method is suitable for the determination of aniline residues in water and fish with the characteristics of easy operation, high accuracy and precision.
A fast analytical method for the determination of aniline in water and fish meat by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. The water sample was mixed with acetonitrile by 4:1 (v/v) and the fish sample was extracted by 2.00 mL acetonitrile for each gram of sample, and then the extracts of water and fish samples were centrifuged at 5000 r/min for 5 min. The separation was performed on a reversed-phase Cl8 column using mobile phases of acetonitrile-0.5%(v/v) formic acid aqueous solution (85:15, v/v). Aniline was separated within 3 min. The calibration curve was linear in the range of 0.5-500 μg/L with R2>0.999. The limits of detection (LODs) were 0.50 μg/L and 1.00 μg/kg and the limits of quantification (LOQs) were 1.00 μg/L and 2.00 μg/kg for aniline in water and fish meat, respectively. The average recoveries of aniline in water were 93.7% at the spiked level of 40 ng and 86.7% at the spiked level of 400 ng (n=5). The average recoveries of aniline in fish were 96.8%, 92.6% and 81.8% at the spiked levels of 5, 50 and 500 ng respectively (n=5). The relative standard deviations were 1.5%-9.2%. Thirteen water samples and twelve fish samples were collected from a reservoir polluted by aniline and the maximum contents found were 1943.6 μg/L in water and 60.8 μg/kg in fish. The method is suitable for the determination of aniline residues in water and fish with the characteristics of easy operation, high accuracy and precision.
2014, 32(9): 930-935
doi: 10.3724/SP.J.1123.2014.05033
Abstract:
The sample pretreatment method for the determination of four typical artificial sweeteners (ASs) including sucralose, saccharin, cyclamate, and acesulfame in soil by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was optimized. Different conditions of extraction, including four extractants (methanol, acetonitrile, acetone, deionized water), three kinds of ionic strength of sodium acetate solution (0.001, 0.01, 0.1 mol/L), four pH values (3, 4, 5 and 6) of 0.01 mol/L acetate-sodium acetate solution, four set durations of extraction (20, 40, 60, 120 min) and number of extraction times (1, 2, 3, 4 times) were compared. The optimal sample pretreatment method was finally set up. The samples were extracted twice with 25 mL 0.01 mol/L sodium acetate solution (pH 4) for 20 min per cycle. The extracts were combined and then purified and concentrated by CNW Poly-Sery PWAX cartridges with methanol containing 1 mmol/L tris(hydroxymethyl) amino methane (Tris) and 5%(v/v) ammonia hydroxide as eluent. The analytes were determined by HPLC-MS/MS. The recoveries were obtained by spiked soil with the four artificial sweeteners at 1, 10, 100 μg/kg (dry weight), separately. The average recoveries of the analytes ranged from 86.5% to 105%. The intra-day and inter-day precisions expressed as relative standard deviations (RSDs) were in the range of 2.56%-5.94% and 3.99%-6.53%, respectively. Good linearities (r2>0.995) were observed between 1-100 μg/kg (dry weight) for all the compounds. The limits of detection were 0.01-0.21 μg/kg and the limits of quantification were 0.03-0.70 μg/kg for the analytes. The four artificial sweeteners were determined in soil samples from farmland contaminated by wastewater in Tianjin. This method is rapid, reliable, and suitable for the investigation of artificial sweeteners in soil.
The sample pretreatment method for the determination of four typical artificial sweeteners (ASs) including sucralose, saccharin, cyclamate, and acesulfame in soil by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was optimized. Different conditions of extraction, including four extractants (methanol, acetonitrile, acetone, deionized water), three kinds of ionic strength of sodium acetate solution (0.001, 0.01, 0.1 mol/L), four pH values (3, 4, 5 and 6) of 0.01 mol/L acetate-sodium acetate solution, four set durations of extraction (20, 40, 60, 120 min) and number of extraction times (1, 2, 3, 4 times) were compared. The optimal sample pretreatment method was finally set up. The samples were extracted twice with 25 mL 0.01 mol/L sodium acetate solution (pH 4) for 20 min per cycle. The extracts were combined and then purified and concentrated by CNW Poly-Sery PWAX cartridges with methanol containing 1 mmol/L tris(hydroxymethyl) amino methane (Tris) and 5%(v/v) ammonia hydroxide as eluent. The analytes were determined by HPLC-MS/MS. The recoveries were obtained by spiked soil with the four artificial sweeteners at 1, 10, 100 μg/kg (dry weight), separately. The average recoveries of the analytes ranged from 86.5% to 105%. The intra-day and inter-day precisions expressed as relative standard deviations (RSDs) were in the range of 2.56%-5.94% and 3.99%-6.53%, respectively. Good linearities (r2>0.995) were observed between 1-100 μg/kg (dry weight) for all the compounds. The limits of detection were 0.01-0.21 μg/kg and the limits of quantification were 0.03-0.70 μg/kg for the analytes. The four artificial sweeteners were determined in soil samples from farmland contaminated by wastewater in Tianjin. This method is rapid, reliable, and suitable for the investigation of artificial sweeteners in soil.
2014, 32(9): 936-941
doi: 10.3724/SP.J.1123.2014.05026
Abstract:
An analytical method using ion chromatography with inductively coupled plasma mass spectrometry (IC-ICP-MS) for the determination of hexavalent chromium (Cr(Ⅵ)) in atmospheric particles PM2.5 and PM10 was established. The Cr(Ⅵ) in the atmospheric particles was extracted ultrasonically with sodium bicarbonate solution. An anion exchange column (AG7, 50 mm×4 mm) with 75 mmol/L ammonium nitrate solution (containing 0.22 g/L Na2EDTA, pH 7.0) as mobile phase was used for the separation. ICP-MS was used as a detector for the determination of hexavalent chromium. The calibration curve was linear in the range of 0.05-5 μg/L and the correlation coefficient was 0.9999 for Cr(Ⅵ). The cellulose filter was fit for sampling. With the alkaline cellulose filter, the recovery of Cr(Ⅵ) increased from 75% to 102%. The recovery was complete and stable when the samples were sonicated in 20 mmol/L sodium bicarbonate solution for 30 min. The limit of quantification (LOQ) of Cr(Ⅵ) was 0.0004 ng/m3 when the sampling volume was 20 m3. The average recoveries of Cr(Ⅵ) in the spiked PM2.5 and PM10 samples ranged from 91.6% to 102% with the relative standard deviations not more than 7.6%. The method is efficient and reliable. It can meet the requirement for the determination of Cr(Ⅵ) in atmospheric particles.
An analytical method using ion chromatography with inductively coupled plasma mass spectrometry (IC-ICP-MS) for the determination of hexavalent chromium (Cr(Ⅵ)) in atmospheric particles PM2.5 and PM10 was established. The Cr(Ⅵ) in the atmospheric particles was extracted ultrasonically with sodium bicarbonate solution. An anion exchange column (AG7, 50 mm×4 mm) with 75 mmol/L ammonium nitrate solution (containing 0.22 g/L Na2EDTA, pH 7.0) as mobile phase was used for the separation. ICP-MS was used as a detector for the determination of hexavalent chromium. The calibration curve was linear in the range of 0.05-5 μg/L and the correlation coefficient was 0.9999 for Cr(Ⅵ). The cellulose filter was fit for sampling. With the alkaline cellulose filter, the recovery of Cr(Ⅵ) increased from 75% to 102%. The recovery was complete and stable when the samples were sonicated in 20 mmol/L sodium bicarbonate solution for 30 min. The limit of quantification (LOQ) of Cr(Ⅵ) was 0.0004 ng/m3 when the sampling volume was 20 m3. The average recoveries of Cr(Ⅵ) in the spiked PM2.5 and PM10 samples ranged from 91.6% to 102% with the relative standard deviations not more than 7.6%. The method is efficient and reliable. It can meet the requirement for the determination of Cr(Ⅵ) in atmospheric particles.
2014, 32(9): 942-947
doi: 10.3724/SP.J.1123.2014.05028
Abstract:
A simple derivatization method followed by high performance liquid chromatography (HPLC) for the analysis of perfluorooctanoic acid (PFOA) was developed. PFOA was firstly derivatized with 3,4-dichloroaniline (DCA) using carbodiimide method. The typical amidate product was characterized by mass spectrometry (MS). It can be detected by a UV detector at maximum absorption wavelength of 255 nm. It was isolated well by methanol/H2O (8/2, v/v) as mobile phase. The DCA derivatization of PFOA in organic or aqueous solutions was optimized. The following purification procedures with thin layer chromatography (TLC) and HPLC separations were established. Using external standard method with the authentic PFOA-DCA derivative as standard, the limit of instrumental quantification was found to be 0.5 mg/L. Good linear correlation coefficients were observed in 0.5-50.0 mg/L. The accuracy of the method was evaluated by the recovery measurements on spiked samples. The recoveries for the spiked samples (1.0 mg/L) in organic phase and aqueous phase were 91.8%-108.7% and 42.1%-53.7%, respectively. Comparing to the reported pre-column derivatization methods followed by HPLC for the determination of PFOA, this method has the advantages of mild reaction conditions, very stable derivative, easy operation, low cost, etc. The method was successfully applied for the quantification of PFOA in photodegradation experiments, and the results were consistent with those determined by LC/MS. Considering the combination of the preconcentration step, it has a potential for the application of the analysis of samples containing relatively low concentrations, such as μg/L levels of PFOA obtained from environmental or scientific experiments.
A simple derivatization method followed by high performance liquid chromatography (HPLC) for the analysis of perfluorooctanoic acid (PFOA) was developed. PFOA was firstly derivatized with 3,4-dichloroaniline (DCA) using carbodiimide method. The typical amidate product was characterized by mass spectrometry (MS). It can be detected by a UV detector at maximum absorption wavelength of 255 nm. It was isolated well by methanol/H2O (8/2, v/v) as mobile phase. The DCA derivatization of PFOA in organic or aqueous solutions was optimized. The following purification procedures with thin layer chromatography (TLC) and HPLC separations were established. Using external standard method with the authentic PFOA-DCA derivative as standard, the limit of instrumental quantification was found to be 0.5 mg/L. Good linear correlation coefficients were observed in 0.5-50.0 mg/L. The accuracy of the method was evaluated by the recovery measurements on spiked samples. The recoveries for the spiked samples (1.0 mg/L) in organic phase and aqueous phase were 91.8%-108.7% and 42.1%-53.7%, respectively. Comparing to the reported pre-column derivatization methods followed by HPLC for the determination of PFOA, this method has the advantages of mild reaction conditions, very stable derivative, easy operation, low cost, etc. The method was successfully applied for the quantification of PFOA in photodegradation experiments, and the results were consistent with those determined by LC/MS. Considering the combination of the preconcentration step, it has a potential for the application of the analysis of samples containing relatively low concentrations, such as μg/L levels of PFOA obtained from environmental or scientific experiments.
2014, 32(9): 948-954
doi: 10.3724/SP.J.1123.2014.05023
Abstract:
In order to evaluate the distributions and concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in aerosol, PM2.5 samples were collected concurrently at five sites in January 2014 in Hangzhou. The analytes were analyzed with isotope dilution and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) based on US EPA 1613B method and US EPA 1668B method. The results showed that the mass concentrations of PM2.5 were in the range of 85-168 μg/m3, which were much higher than the national quality standard. The values suggested that the PM2.5 pollution was relatively serious in Hangzhou City, yet it has been improved when compared with the results of 2004. The toxic equivalent quantities (TEQs) of PCDD/Fs in PM2.5 were in the range of 0.277-0.488 pg I-TEQ/m3, which were much higher than the results in 2004. Octachlorodibenzo-p-dioxin(OCDD) accounted for a large proportion to the total concentrations in PCDD/Fs, while 2,3,4,7,8-pentachlorodibenzofurans (2,3,4,7,8-PeCDF) contributed the highest to the TEQ. The values of PCBs and dioxin-like PCBs (DL-PCBs) varied from 2.9-8.1 pg/m3 and 2.6-6.1 fg WHO-TEQ/m3, respectively. PCB-28 was the most abundant contributor to the concentrations of PCBs, while PCB-126 contributed the highest to the TEQ of DL-PCBs. Gas-particle distributions of PCDD/Fs and PCBs shows that PCDD/Fs were mainly distributed in the particle phase, but PCBs were preferably adsorbed in the gas phase.
In order to evaluate the distributions and concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in aerosol, PM2.5 samples were collected concurrently at five sites in January 2014 in Hangzhou. The analytes were analyzed with isotope dilution and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) based on US EPA 1613B method and US EPA 1668B method. The results showed that the mass concentrations of PM2.5 were in the range of 85-168 μg/m3, which were much higher than the national quality standard. The values suggested that the PM2.5 pollution was relatively serious in Hangzhou City, yet it has been improved when compared with the results of 2004. The toxic equivalent quantities (TEQs) of PCDD/Fs in PM2.5 were in the range of 0.277-0.488 pg I-TEQ/m3, which were much higher than the results in 2004. Octachlorodibenzo-p-dioxin(OCDD) accounted for a large proportion to the total concentrations in PCDD/Fs, while 2,3,4,7,8-pentachlorodibenzofurans (2,3,4,7,8-PeCDF) contributed the highest to the TEQ. The values of PCBs and dioxin-like PCBs (DL-PCBs) varied from 2.9-8.1 pg/m3 and 2.6-6.1 fg WHO-TEQ/m3, respectively. PCB-28 was the most abundant contributor to the concentrations of PCBs, while PCB-126 contributed the highest to the TEQ of DL-PCBs. Gas-particle distributions of PCDD/Fs and PCBs shows that PCDD/Fs were mainly distributed in the particle phase, but PCBs were preferably adsorbed in the gas phase.
2014, 32(9): 955-959
doi: 10.3724/SP.J.1123.2014.05030
Abstract:
A method for the determination of mono- to tri- chlorinated dibenzo-p-dioxins and dibenzofurans (mono- to tri-CDD/Fs) in stack gas using isotope dilution high resolution gas chromatography-high resolution mass spectrometry (HRGC-HRMS) was developed. The samples were extracted by Soxhlet extraction, and then the extracts were concentrated and purified using a multilayer silica gel column and a basic alumina column. The analytes were separated by HRGC on a DB-5MS column (30 m×0.25 mm×0.25 μm) and determined by HRMS. The identification of mono- to tri-CDD/Fs was based on the retention times of 13C-labelled standard and the abundance ratios of the two exacted mass-to-charge ratios. The quantitative analysis was performed using the ratios of the integrated areas of the 13C-labelled standards. This method had the recoveries ranging from 66.6% to 112.5% and the relative standard deviations (RSD) ranging from 19.9% to 40.5% (n=5). The limits of detection (LODs) of this method for the mono- to tri-CDD/Fs were ranging from 0.027 to 0.485 μg/L. Three stack gas samples from waste incinerators were measured using this method, with the recoveries ranging from 85.7% to 137.0% and the concentrations ranging from 11.4 to 9183 pg/Nm3. The results indicated that the method can be applied to the precise determination of mono- to tri-CDD/Fs at trace level in stack gas.
A method for the determination of mono- to tri- chlorinated dibenzo-p-dioxins and dibenzofurans (mono- to tri-CDD/Fs) in stack gas using isotope dilution high resolution gas chromatography-high resolution mass spectrometry (HRGC-HRMS) was developed. The samples were extracted by Soxhlet extraction, and then the extracts were concentrated and purified using a multilayer silica gel column and a basic alumina column. The analytes were separated by HRGC on a DB-5MS column (30 m×0.25 mm×0.25 μm) and determined by HRMS. The identification of mono- to tri-CDD/Fs was based on the retention times of 13C-labelled standard and the abundance ratios of the two exacted mass-to-charge ratios. The quantitative analysis was performed using the ratios of the integrated areas of the 13C-labelled standards. This method had the recoveries ranging from 66.6% to 112.5% and the relative standard deviations (RSD) ranging from 19.9% to 40.5% (n=5). The limits of detection (LODs) of this method for the mono- to tri-CDD/Fs were ranging from 0.027 to 0.485 μg/L. Three stack gas samples from waste incinerators were measured using this method, with the recoveries ranging from 85.7% to 137.0% and the concentrations ranging from 11.4 to 9183 pg/Nm3. The results indicated that the method can be applied to the precise determination of mono- to tri-CDD/Fs at trace level in stack gas.
2014, 32(9): 960-966
doi: 10.3724/SP.J.1123.2014.05027
Abstract:
A method of gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-MS/MS) has been optimized for the determination of polycyclic aromatic hydrocarbons (PAHs) in air samples. In the analysis step, isotope dilution was introduced to the quantification of PAHs. The GC-MS/MS method was applied to the analysis of the real air samples around a big petrochemical power plant in South China. The results were compared with those obtained by gas chromatography coupled to mass spectrometry (GC-MS). The results showed that better selectivity and sensitivity were obtained by GC-MS/MS. It was found that the external standard of deuterated-PAHs and internal standard of hexamethyl benzene were disturbed seriously with GC-MS, and the problems were both solved effectively by GC-MS/MS. Therefore more accurate quantification results of PAHs were obtained with GC-MS/MS. For the analysis of real samples, the RSDs of relative response factors ranged from 2.60% to 15.6% in standard curves; the recoveries of deuterated-PAHs ranged from 55.2% to 82.3%; the recoveries of spiked samples ranged from 98.9% to 111%; the RSDs of parallel specimens ranged from 6.50% to 18.4%; the concentrations of field blank samples ranged from not detected to 44.3 pg/m3; and the concentrations of library blank samples ranged from not detected to 36.5 pg/m3. The study indicated that the application of GC-MS/MS on the analysis of PAHs in air samples was recommended.
A method of gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-MS/MS) has been optimized for the determination of polycyclic aromatic hydrocarbons (PAHs) in air samples. In the analysis step, isotope dilution was introduced to the quantification of PAHs. The GC-MS/MS method was applied to the analysis of the real air samples around a big petrochemical power plant in South China. The results were compared with those obtained by gas chromatography coupled to mass spectrometry (GC-MS). The results showed that better selectivity and sensitivity were obtained by GC-MS/MS. It was found that the external standard of deuterated-PAHs and internal standard of hexamethyl benzene were disturbed seriously with GC-MS, and the problems were both solved effectively by GC-MS/MS. Therefore more accurate quantification results of PAHs were obtained with GC-MS/MS. For the analysis of real samples, the RSDs of relative response factors ranged from 2.60% to 15.6% in standard curves; the recoveries of deuterated-PAHs ranged from 55.2% to 82.3%; the recoveries of spiked samples ranged from 98.9% to 111%; the RSDs of parallel specimens ranged from 6.50% to 18.4%; the concentrations of field blank samples ranged from not detected to 44.3 pg/m3; and the concentrations of library blank samples ranged from not detected to 36.5 pg/m3. The study indicated that the application of GC-MS/MS on the analysis of PAHs in air samples was recommended.
2014, 32(9): 967-970
doi: 10.3724/SP.J.1123.2014.05022
Abstract:
Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil samples were analyzed by isotope dilution method with high resolution gas chromatography and high resolution mass spectrometry (ID-HRGC/HRMS), and the toxic equivalent quantity (TEQ) were calculated. The impacts of major source of measurement uncertainty are discussed, and the combined relative standard uncertainties were calculated for each 2,3,7,8 substituted congener. Furthermore, the concentration, combined uncertainty and expanded uncertainty for TEQ of PCDD/Fs in a soil sample in I-TEF, WHO-1998-TEF and WHO-2005-TEF schemes are provided as an example. I-TEF, WHO-1998-TEF and WHO-2005-TEF are the evaluation schemes of toxic equivalent factor (TEF), and are all currently used to describe 2,3,7,8 substituted relative potencies.
Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil samples were analyzed by isotope dilution method with high resolution gas chromatography and high resolution mass spectrometry (ID-HRGC/HRMS), and the toxic equivalent quantity (TEQ) were calculated. The impacts of major source of measurement uncertainty are discussed, and the combined relative standard uncertainties were calculated for each 2,3,7,8 substituted congener. Furthermore, the concentration, combined uncertainty and expanded uncertainty for TEQ of PCDD/Fs in a soil sample in I-TEF, WHO-1998-TEF and WHO-2005-TEF schemes are provided as an example. I-TEF, WHO-1998-TEF and WHO-2005-TEF are the evaluation schemes of toxic equivalent factor (TEF), and are all currently used to describe 2,3,7,8 substituted relative potencies.
2014, 32(9): 971-974
doi: 10.3724/SP.J.1123.2014.05031
Abstract:
Two interference peaks which generally appeared in company with 13C labeled 2,3,7,8-tetrachlorodibenzofuran (13C12-2,3,7,8-TCDF) in the same ion channel during dioxin analysis for biological samples were identified using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) and high resolution gas chromatography/low resolution mass spectrometry (HRGC/LRMS). It was firstly inferred that the interference peaks should be the two isomers of dichlorodiphenyldichloroethylene (DDE), which was a breakdown product of dichlorodiphenyltrichloroethane (DDT), one of the typical organic chlorine pesticides (OCPs). Thereafter, the standard solution of DDE including o,p'-DDE and p,p'-DDE was analyzed for confirmation. By evaluation of the peak separation in HRGC/HRMS, comparison of the GC retention times and ion abundance ratios of the two interference peaks in real samples with the two DDE isomers in standard solution, the interference peaks were finally confirmed as o,p'-DDE and p,p'-DDE in sequence on a DB-5MS column. This study provided valuable information for accurate identification of dioxin compounds during the biological sample analysis.
Two interference peaks which generally appeared in company with 13C labeled 2,3,7,8-tetrachlorodibenzofuran (13C12-2,3,7,8-TCDF) in the same ion channel during dioxin analysis for biological samples were identified using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) and high resolution gas chromatography/low resolution mass spectrometry (HRGC/LRMS). It was firstly inferred that the interference peaks should be the two isomers of dichlorodiphenyldichloroethylene (DDE), which was a breakdown product of dichlorodiphenyltrichloroethane (DDT), one of the typical organic chlorine pesticides (OCPs). Thereafter, the standard solution of DDE including o,p'-DDE and p,p'-DDE was analyzed for confirmation. By evaluation of the peak separation in HRGC/HRMS, comparison of the GC retention times and ion abundance ratios of the two interference peaks in real samples with the two DDE isomers in standard solution, the interference peaks were finally confirmed as o,p'-DDE and p,p'-DDE in sequence on a DB-5MS column. This study provided valuable information for accurate identification of dioxin compounds during the biological sample analysis.
2014, 32(9): 975-980
doi: 10.3724/SP.J.1123.2014.05011
Abstract:
Heterocyclic amines (HAs) are considered as highly potential mutagens and carcinogens in cooked meat products. Efficient sample pretreatment as well as sensitive analytical method is very important for the determination of HAs in complex samples. In this paper, some sample pretreatment methods such as solvent extraction, solid-phase extraction, and solid-phase microextraction as well as analytical methods including liquid chromatography, and liquid chromatography-mass spectrometry are reviewed; The progress of HAs analysis is also prospected. A total of 51 references are cited.
Heterocyclic amines (HAs) are considered as highly potential mutagens and carcinogens in cooked meat products. Efficient sample pretreatment as well as sensitive analytical method is very important for the determination of HAs in complex samples. In this paper, some sample pretreatment methods such as solvent extraction, solid-phase extraction, and solid-phase microextraction as well as analytical methods including liquid chromatography, and liquid chromatography-mass spectrometry are reviewed; The progress of HAs analysis is also prospected. A total of 51 references are cited.
2014, 32(9): 981-987
doi: 10.3724/SP.J.1123.2014.07005
Abstract:
A new boronate affinity monolithic material was prepared and used as the extraction medium of stir cake sorptive extraction (SCSE). The porous boronate affinity sorbent was prepared by in situ copolymerization of 3-acrylamidophenylboronic acid (APB) and divinyl benzene (DVB). To achieve optimum extraction performance for benzoylurea pesticides, several parameters, including desorption solvent, pH value, ionic strength in sample matrix, extraction and desorption times, were investigated in detail. At the same time, a simple, sensitive and environment friendly method for the determination of benzoylurea pesticides in water and juice samples was developed by the combination of SCSE-APBDVB with HPLC equipped with a diode array detector. Under the optimized experimental conditions, the limits of detection (S/N=3) for target analytes were 0.055-0.11 μg/L in water and 0.095-0.31 μg/L in juice. The precision of the proposed method was evaluated in terms of intra- and inter-assay repeatability calculated as RSD, and it was found that the RSDs were all below 9.0%. The developed method was successfully applied to the determination of benzoylurea pesticide residues in water and juice samples and satisfactory recoveries of spiked target compounds were in the range of 75.6%-109%. The results well demonstrate that the new sorbent can extract benzoylurea pesticides effectively through multi-interactions including boron-nitrogen coordination, hydrogen-bond and hydrophobic interactions between sorbent and analytes.
A new boronate affinity monolithic material was prepared and used as the extraction medium of stir cake sorptive extraction (SCSE). The porous boronate affinity sorbent was prepared by in situ copolymerization of 3-acrylamidophenylboronic acid (APB) and divinyl benzene (DVB). To achieve optimum extraction performance for benzoylurea pesticides, several parameters, including desorption solvent, pH value, ionic strength in sample matrix, extraction and desorption times, were investigated in detail. At the same time, a simple, sensitive and environment friendly method for the determination of benzoylurea pesticides in water and juice samples was developed by the combination of SCSE-APBDVB with HPLC equipped with a diode array detector. Under the optimized experimental conditions, the limits of detection (S/N=3) for target analytes were 0.055-0.11 μg/L in water and 0.095-0.31 μg/L in juice. The precision of the proposed method was evaluated in terms of intra- and inter-assay repeatability calculated as RSD, and it was found that the RSDs were all below 9.0%. The developed method was successfully applied to the determination of benzoylurea pesticide residues in water and juice samples and satisfactory recoveries of spiked target compounds were in the range of 75.6%-109%. The results well demonstrate that the new sorbent can extract benzoylurea pesticides effectively through multi-interactions including boron-nitrogen coordination, hydrogen-bond and hydrophobic interactions between sorbent and analytes.
2014, 32(9): 988-991
doi: 10.3724/SP.J.1123.2014.06008
Abstract:
A sensitive method was developed for the simultaneous determination of 11 bisphenols in plastic bottled drinking water by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were freeze-dried under vacuum and then dissolved with methanol. The separation was performed on a UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm) by using 0.1%(v/v) NH3·5H2O and methanol as mobile phases with gradient elution at a flow rate of 0.2 mL/min. The electrospray ionization (ESI) source in negative ion mode was used for the analysis of the 11 bisphenols in the multiple reaction monitoring (MRM) mode. The results verified that the standard curves for the 11 bisphenols were obtained with good correlation coefficients (R2)>0.997 in their concentration ranges. The limits of detection (LOD, S/N=3) for the 11 bisphenols were in the range of 0.01-1.00 μg/L. The mean recoveries for the 11 bisphenols at three spiked levels (low, middle, high) were 75.3%-102.1% with the relative standard deviations of 1.5%-8.9%. Seven plastic bottled drinking water samples were tested, and no bisphenol was found. The method is accurate, simple, rapid and feasible for the simultaneous determination of bisphenols in plastic bottled drinking water.
A sensitive method was developed for the simultaneous determination of 11 bisphenols in plastic bottled drinking water by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were freeze-dried under vacuum and then dissolved with methanol. The separation was performed on a UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm) by using 0.1%(v/v) NH3·5H2O and methanol as mobile phases with gradient elution at a flow rate of 0.2 mL/min. The electrospray ionization (ESI) source in negative ion mode was used for the analysis of the 11 bisphenols in the multiple reaction monitoring (MRM) mode. The results verified that the standard curves for the 11 bisphenols were obtained with good correlation coefficients (R2)>0.997 in their concentration ranges. The limits of detection (LOD, S/N=3) for the 11 bisphenols were in the range of 0.01-1.00 μg/L. The mean recoveries for the 11 bisphenols at three spiked levels (low, middle, high) were 75.3%-102.1% with the relative standard deviations of 1.5%-8.9%. Seven plastic bottled drinking water samples were tested, and no bisphenol was found. The method is accurate, simple, rapid and feasible for the simultaneous determination of bisphenols in plastic bottled drinking water.
2014, 32(9): 992-998
doi: 10.3724/SP.J.1123.2014.06016
Abstract:
A quantitative method based on high performance liquid chromatography coupled with electrospray ionization tandem triple-quadrupole mass spectrometry (HPLC-ESI-QqQ-MS) has been established for five pigments in marine phytoplanktons. The HPLC method used ternary solvent systems and a reversed-phase C16-amide column. In addition, methanol, acetonitrile and aqueous ammonium acetate were used as mobile phases. Five pigments (chlorophyll a, chlorophyll b, β, β -carotene, lutein and fucoxanthin) were quantified in selective reaction mode. As results, good linear relationships were achieved between the concentrations and the peak areas of the five pigment standards. And their correlation coefficients (r2) were higher than 0.996. The recoveries of the pigment standards were between 82.77% and 99.83%. The inter-day and intra-day precisions were lower than 5% (n=5). The detection limits of the pigments for this method were between 0.02 and 0.16 μg/L and the quantification limits were in the range from 0.06 to 0.54 μg/L. According to the above method, eleven algae (Heterosigma akashiwo (NMBRah03-2), Heterosigma akashiwo (NMBRah03-2-2), Karlodinium veneficum (NMBjah047-1), Prorocentrum minimum (NMBjah042), Nannochloropsis oceanic (NMBluh014), Chlorella pyrenoidosa (NMBluh015-1), Pleurochrysis sp. (NMBjih026-1), Prymnesium sp. (NMBjih029), Skeletonema costatum (NMBguh004-1), Thalassiosira weissflogii (NMBguh021) and Thalassiosira pseudonana) (NMBguh005)) have been investigated for comparing the pigment distributions. The method is sensitive, accurate, reproducible, and useful for the study of alga compositions.
A quantitative method based on high performance liquid chromatography coupled with electrospray ionization tandem triple-quadrupole mass spectrometry (HPLC-ESI-QqQ-MS) has been established for five pigments in marine phytoplanktons. The HPLC method used ternary solvent systems and a reversed-phase C16-amide column. In addition, methanol, acetonitrile and aqueous ammonium acetate were used as mobile phases. Five pigments (chlorophyll a, chlorophyll b, β, β -carotene, lutein and fucoxanthin) were quantified in selective reaction mode. As results, good linear relationships were achieved between the concentrations and the peak areas of the five pigment standards. And their correlation coefficients (r2) were higher than 0.996. The recoveries of the pigment standards were between 82.77% and 99.83%. The inter-day and intra-day precisions were lower than 5% (n=5). The detection limits of the pigments for this method were between 0.02 and 0.16 μg/L and the quantification limits were in the range from 0.06 to 0.54 μg/L. According to the above method, eleven algae (Heterosigma akashiwo (NMBRah03-2), Heterosigma akashiwo (NMBRah03-2-2), Karlodinium veneficum (NMBjah047-1), Prorocentrum minimum (NMBjah042), Nannochloropsis oceanic (NMBluh014), Chlorella pyrenoidosa (NMBluh015-1), Pleurochrysis sp. (NMBjih026-1), Prymnesium sp. (NMBjih029), Skeletonema costatum (NMBguh004-1), Thalassiosira weissflogii (NMBguh021) and Thalassiosira pseudonana) (NMBguh005)) have been investigated for comparing the pigment distributions. The method is sensitive, accurate, reproducible, and useful for the study of alga compositions.
2014, 32(9): 999-1004
doi: 10.3724/SP.J.1123.2014.05014
Abstract:
An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method has been developed to identify and determine 11 industrial antioxidants in the aqueous simulants. A ProElut PLS SPE column was used for the enrichment, and an ACQUITY UPLCTM BEH C18 UPLC column (100 mm×2.1 mm, 1.7 μm) was used for separation by the gradient elution with pure water and acetonitrile as the mobile phases. The MS/MS detection was performed with an electrospray ionization (ESI) source in negative mode. The external standard method was used for quantitation in the present study. The linear ranges of the 11 analytes were from 5.0 to 100 μg/L. The coefficients of correlation were greater than 0.995. The recoveries of blank aqueous simulants fortified with the 11 analytes at the levels of 5.0, 10.0 and 20.0 μg/L were 61.4% to 109.4% with the relative standard deviations varied from 3.9% to 18.2% (n=6). The LODs and LOQs of the 11 analytes in aqueous simulants were 0.2-1.0 μg/L and 0.5-3.0 μg/L, respectively. This method is highly sensitive and accurate, and can be applied to the determination of the 11 trace industrial antioxidants in the aqueous simulants.
An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method has been developed to identify and determine 11 industrial antioxidants in the aqueous simulants. A ProElut PLS SPE column was used for the enrichment, and an ACQUITY UPLCTM BEH C18 UPLC column (100 mm×2.1 mm, 1.7 μm) was used for separation by the gradient elution with pure water and acetonitrile as the mobile phases. The MS/MS detection was performed with an electrospray ionization (ESI) source in negative mode. The external standard method was used for quantitation in the present study. The linear ranges of the 11 analytes were from 5.0 to 100 μg/L. The coefficients of correlation were greater than 0.995. The recoveries of blank aqueous simulants fortified with the 11 analytes at the levels of 5.0, 10.0 and 20.0 μg/L were 61.4% to 109.4% with the relative standard deviations varied from 3.9% to 18.2% (n=6). The LODs and LOQs of the 11 analytes in aqueous simulants were 0.2-1.0 μg/L and 0.5-3.0 μg/L, respectively. This method is highly sensitive and accurate, and can be applied to the determination of the 11 trace industrial antioxidants in the aqueous simulants.
2014, 32(9): 1005-1012
doi: 10.3724/SP.J.1123.2014.04041
Abstract:
A method of ultra-performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (UPLC-LTQ/Orbitrap MS) was used to screen and confirm 24 banned aromatic amines and their 14 isomers at the same time. The main factors influencing the separation including the column, and the nature of make-up solvent were optimized. Under the optimized experimental conditions, the analytes were reduced to banned aromatic amine with sodium dithionite, extracted by methyl tert-butyl ether and loaded onto a ZORBAX SB-C18 column (150 mm×2.1 mm, 5 μm) with a gradient elution of methanol and 0.1% formic acid aqueous solution, and finally detected by LTQ/Orbitrap MS. The screening and quantitative analysis were carried out by the accurate mass of quasi-molecular ion and the peak in extracted chromatogram with accurate mass. The correlation coefficients were higher than 0.99 and the limits of detection were in the range of 0.5-5 μg/kg. The method could screen and confirm the 24 banned aromatic amines and their 14 isomers at the same time. The results were 1.56 mg/kg of 4-chloroaniline, 0.34 mg/kg of o-toluidine, and 0.81 mg/kg of 2,6-toluylenediamine with the relative standard deviations ranging from 0.27% to 1.32% in actual samples. The results indicate that the developed method is simple, efficient and precise, and can be a reliable technique for the separation of the 24 banned aromatic amines and their 14 isomers in textile samples.
A method of ultra-performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (UPLC-LTQ/Orbitrap MS) was used to screen and confirm 24 banned aromatic amines and their 14 isomers at the same time. The main factors influencing the separation including the column, and the nature of make-up solvent were optimized. Under the optimized experimental conditions, the analytes were reduced to banned aromatic amine with sodium dithionite, extracted by methyl tert-butyl ether and loaded onto a ZORBAX SB-C18 column (150 mm×2.1 mm, 5 μm) with a gradient elution of methanol and 0.1% formic acid aqueous solution, and finally detected by LTQ/Orbitrap MS. The screening and quantitative analysis were carried out by the accurate mass of quasi-molecular ion and the peak in extracted chromatogram with accurate mass. The correlation coefficients were higher than 0.99 and the limits of detection were in the range of 0.5-5 μg/kg. The method could screen and confirm the 24 banned aromatic amines and their 14 isomers at the same time. The results were 1.56 mg/kg of 4-chloroaniline, 0.34 mg/kg of o-toluidine, and 0.81 mg/kg of 2,6-toluylenediamine with the relative standard deviations ranging from 0.27% to 1.32% in actual samples. The results indicate that the developed method is simple, efficient and precise, and can be a reliable technique for the separation of the 24 banned aromatic amines and their 14 isomers in textile samples.
2014, 32(9): 1013-1018
doi: 10.3724/SP.J.1123.2014.06026
Abstract:
Chromatographic behaviors for enantiomeric separation of arylpropionic acid drugs were systematically developed by reversed phase-high performance liquid chromatography (RP-HPLC) using cellulose-tris-(4-methylbenzoate) (CTMB) as chiral stationary phase (CSP). The effects of the composition of the mobile phase, additives and temperature on chiral separation of flurbiprofen, pranoprofen, naproxen, ibuprofen and loxoprofen were further investigated. The enantiomers had been successfully separated on CSP of CTMB by the mobile phase of methanol-0.1%(v/v) formic acid except naproxen by acetonitrile-0.1%(v/v) formic acid at 25 ℃. The mechanisms of the racemic resolution for the above mentioned five drugs are discussed thermodynamically and structurally. The resolutions between respective enantiomers for arylpropionic acid drugs on CTMB had significant differences due to their chromatographic behaviors. The order of resolutions ranked pranoprofen, loxoprofen, flurbiprofen, ibuprofen and naproxen. The method established has been successfully applied to the determination of the enantiomers of the five drugs in commercial preparations under the optimized conditions. It proved that the method is simple, reliable and accurate.
Chromatographic behaviors for enantiomeric separation of arylpropionic acid drugs were systematically developed by reversed phase-high performance liquid chromatography (RP-HPLC) using cellulose-tris-(4-methylbenzoate) (CTMB) as chiral stationary phase (CSP). The effects of the composition of the mobile phase, additives and temperature on chiral separation of flurbiprofen, pranoprofen, naproxen, ibuprofen and loxoprofen were further investigated. The enantiomers had been successfully separated on CSP of CTMB by the mobile phase of methanol-0.1%(v/v) formic acid except naproxen by acetonitrile-0.1%(v/v) formic acid at 25 ℃. The mechanisms of the racemic resolution for the above mentioned five drugs are discussed thermodynamically and structurally. The resolutions between respective enantiomers for arylpropionic acid drugs on CTMB had significant differences due to their chromatographic behaviors. The order of resolutions ranked pranoprofen, loxoprofen, flurbiprofen, ibuprofen and naproxen. The method established has been successfully applied to the determination of the enantiomers of the five drugs in commercial preparations under the optimized conditions. It proved that the method is simple, reliable and accurate.
2014, 32(9): 1019-1024
doi: 10.3724/SP.J.1123.2014.05008
Abstract:
In the field of the chromatographic peak identification of the transformer oil, the traditional first-order derivative requires slope threshold to achieve peak identification. In terms of its shortcomings of low automation and easy distortion, the first-order derivative method was improved by applying the moving average iterative method and the normalized analysis techniques to identify the peaks. Accurate identification of the chromatographic peaks was realized through using multiple iterations of the moving average of signal curves and square wave curves to determine the optimal value of the normalized peak identification parameters, combined with the absolute peak retention times and peak window. The experimental results show that this algorithm can accurately identify the peaks and is not sensitive to the noise, the chromatographic peak width or the peak shape changes. It has strong adaptability to meet the on-site requirements of online monitoring devices of dissolved gases in transformer oil.
In the field of the chromatographic peak identification of the transformer oil, the traditional first-order derivative requires slope threshold to achieve peak identification. In terms of its shortcomings of low automation and easy distortion, the first-order derivative method was improved by applying the moving average iterative method and the normalized analysis techniques to identify the peaks. Accurate identification of the chromatographic peaks was realized through using multiple iterations of the moving average of signal curves and square wave curves to determine the optimal value of the normalized peak identification parameters, combined with the absolute peak retention times and peak window. The experimental results show that this algorithm can accurately identify the peaks and is not sensitive to the noise, the chromatographic peak width or the peak shape changes. It has strong adaptability to meet the on-site requirements of online monitoring devices of dissolved gases in transformer oil.
