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2017 Volume 35 Issue 8
2017, 35(8): 787-793
doi: 10.3724/SP.J.1123.2017.03024
Abstract:
A fast sample pretreatment method by fast pesticide extraction (FaPEx) method combined with ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry was developed for screening of unknown pesticide residues in imported grains. The samples were extracted with 1% (v/v) acetic acid acetonitrile solution, cleaned-up by solid phase extraction column with FaPEx cartridges, and determined by UPLC-Q-TOF. The data was compared with the library with the accurate mass, isotopic distribution, fragmentation information and retention time. The results showed that this method can be used for the rapid screening of pesticide residues in imported grains without the reference standards, and it was applied to the actual screening of imported grain samples. The method is high efficiency, sensitivity and accuracy, which can meet the requirement for the rapid screening of pesticide residues in imported grains.
A fast sample pretreatment method by fast pesticide extraction (FaPEx) method combined with ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry was developed for screening of unknown pesticide residues in imported grains. The samples were extracted with 1% (v/v) acetic acid acetonitrile solution, cleaned-up by solid phase extraction column with FaPEx cartridges, and determined by UPLC-Q-TOF. The data was compared with the library with the accurate mass, isotopic distribution, fragmentation information and retention time. The results showed that this method can be used for the rapid screening of pesticide residues in imported grains without the reference standards, and it was applied to the actual screening of imported grain samples. The method is high efficiency, sensitivity and accuracy, which can meet the requirement for the rapid screening of pesticide residues in imported grains.
2017, 35(8): 794-800
doi: 10.3724/SP.J.1123.2017.04018
Abstract:
An analytical method was developed for the simultaneous and rapid determination of seven microcystins in fish meat by liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with pass-through solid phase extraction (SPE). The samples were extracted with methanol-water (90:10, v/v) after heat treatment by water bath at 80℃, and then cleaned up with an Oasis PRiME HLB pass-through SPE column. The samples were analyzed directly on a Waters XSelect HSS T3 column using 0.1% (v/v) aqueous formic acid and acidified acetonitrile (0.1% formic acid, v/v) as mobile phases. Qualitative and quantitative analysis of the analytes was carried out under the multiple reaction monitoring mode with positive electrospray ionization. The matrix matching external standard method was used for quantitation analysis. To solve the problem of parent ion selection of the microcystins, the ionization characteristics of microcystins were evaluated under different mobile phase conditions. Finally, the results showed that the acid could promote the intensity of the doubly charged ions significantly. The calibration curves were linear well in the corresponding concentration ranges, with correlation coefficient ≥ 0.99. The limits of quantification ranged from 0.30 to 2.0 μ g/kg. The average spiked recoveries for the seven microcystins were between 70.6% and 96.1% with the relative standard deviations of 3.4%-9.6%. The proposed method is sensitive, accurate, and efficient. It is applicable for the determination of microcystins in fish meat.
An analytical method was developed for the simultaneous and rapid determination of seven microcystins in fish meat by liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with pass-through solid phase extraction (SPE). The samples were extracted with methanol-water (90:10, v/v) after heat treatment by water bath at 80℃, and then cleaned up with an Oasis PRiME HLB pass-through SPE column. The samples were analyzed directly on a Waters XSelect HSS T3 column using 0.1% (v/v) aqueous formic acid and acidified acetonitrile (0.1% formic acid, v/v) as mobile phases. Qualitative and quantitative analysis of the analytes was carried out under the multiple reaction monitoring mode with positive electrospray ionization. The matrix matching external standard method was used for quantitation analysis. To solve the problem of parent ion selection of the microcystins, the ionization characteristics of microcystins were evaluated under different mobile phase conditions. Finally, the results showed that the acid could promote the intensity of the doubly charged ions significantly. The calibration curves were linear well in the corresponding concentration ranges, with correlation coefficient ≥ 0.99. The limits of quantification ranged from 0.30 to 2.0 μ g/kg. The average spiked recoveries for the seven microcystins were between 70.6% and 96.1% with the relative standard deviations of 3.4%-9.6%. The proposed method is sensitive, accurate, and efficient. It is applicable for the determination of microcystins in fish meat.
2017, 35(8): 801-807
doi: 10.3724/SP.J.1123.2017.03043
Abstract:
A method for simultaneous determination of chlorpromazine, diazepam and metolazone residues in porcine muscle, fish, liver and kidney was developed using QuEChERS and HPLC-MS/MS technique. The samples were extracted with ethyl acetate and cleaned up with C18, N-propylethylendiamine (PSA) and NH2 sorbents after using Na2SO4 as dehydrating agent. The analytes were separated by a special C18 column, Atlantis T3, and gradiently eluted with a mixed solution of 5 mmol/L formic acid and acetonitrile at a flow rate of 0.35 mL/min. The mass spectrometric analysis that quantified using isotope internal standard, was carried out with electrospray positive ion source (ESI+) and multiple reaction monitoring mode (MRM). The linearity of the calibration curves was good in the range of 0.2-5.0 μ g/L. The recoveries at three different spiked levels (0.5, 1 and 5 μ g/kg) in four matrices were in the range of 92.5%-117.8%. The repeatability expressed as relative standard deviations (RSDs) ranged from 0.7% to 11.6% (n=6). The method, with wide matrix range of application, is highly effective and sensitive and suitable for the rapid analysis of large quantities of samples.
A method for simultaneous determination of chlorpromazine, diazepam and metolazone residues in porcine muscle, fish, liver and kidney was developed using QuEChERS and HPLC-MS/MS technique. The samples were extracted with ethyl acetate and cleaned up with C18, N-propylethylendiamine (PSA) and NH2 sorbents after using Na2SO4 as dehydrating agent. The analytes were separated by a special C18 column, Atlantis T3, and gradiently eluted with a mixed solution of 5 mmol/L formic acid and acetonitrile at a flow rate of 0.35 mL/min. The mass spectrometric analysis that quantified using isotope internal standard, was carried out with electrospray positive ion source (ESI+) and multiple reaction monitoring mode (MRM). The linearity of the calibration curves was good in the range of 0.2-5.0 μ g/L. The recoveries at three different spiked levels (0.5, 1 and 5 μ g/kg) in four matrices were in the range of 92.5%-117.8%. The repeatability expressed as relative standard deviations (RSDs) ranged from 0.7% to 11.6% (n=6). The method, with wide matrix range of application, is highly effective and sensitive and suitable for the rapid analysis of large quantities of samples.
2017, 35(8): 808-815
doi: 10.3724/SP.J.1123.2017.03035
Abstract:
A method for the determination of 11 mycotoxins in baked foods and raw materials by ultra-high performance liquid chromatography-quadrupole/electrostatic field orbitrap high-resolution mass spectrometry (UPLC-HRMS) is reported in this paper. The samples were extracted with 20 mL 90% (v/v) acetonitrile aqueous solution containing 1% (v/v) formic acid, and the extracts were salted out by 2.0 g MgSO4 and 0.5 g NaCl, cleaned up by 300 mg C18. The analytes were carried out on a CORTECS C18 column (100 mm×2.1 mm, 1.6 μ m) by gradient elution with 2 mmol/L ammonium acetate with 0.1% (v/v) formic acid aqueous solution and 2 mmol/L ammonium acetate methanol with 0.1% (v/v) formic acid. The results showed that the 11 mycotoxins had good linear relationships in their respective mass concentration ranges. The correlation coefficients were not less than 0.9960 and the limits of quantitation (LOQs) were from 0.15 to 20.00 μ g/kg. The recoveries of the 11 mycotoxins in bread ranged from 64.38% to 122.61% with the relative standard deviations (RSDs) from 1.52% to 12.99% at three spiked levels (n=6). The method is demonstrated to be simple, fast, highly sensitive, reliable and it is effective to detect common mycotoxins in baked foods and raw materials.
A method for the determination of 11 mycotoxins in baked foods and raw materials by ultra-high performance liquid chromatography-quadrupole/electrostatic field orbitrap high-resolution mass spectrometry (UPLC-HRMS) is reported in this paper. The samples were extracted with 20 mL 90% (v/v) acetonitrile aqueous solution containing 1% (v/v) formic acid, and the extracts were salted out by 2.0 g MgSO4 and 0.5 g NaCl, cleaned up by 300 mg C18. The analytes were carried out on a CORTECS C18 column (100 mm×2.1 mm, 1.6 μ m) by gradient elution with 2 mmol/L ammonium acetate with 0.1% (v/v) formic acid aqueous solution and 2 mmol/L ammonium acetate methanol with 0.1% (v/v) formic acid. The results showed that the 11 mycotoxins had good linear relationships in their respective mass concentration ranges. The correlation coefficients were not less than 0.9960 and the limits of quantitation (LOQs) were from 0.15 to 20.00 μ g/kg. The recoveries of the 11 mycotoxins in bread ranged from 64.38% to 122.61% with the relative standard deviations (RSDs) from 1.52% to 12.99% at three spiked levels (n=6). The method is demonstrated to be simple, fast, highly sensitive, reliable and it is effective to detect common mycotoxins in baked foods and raw materials.
2017, 35(8): 816-825
doi: 10.3724/SP.J.1123.2017.04005
Abstract:
A novel method was developed for the simultaneous rapid determination of 81 illegally added glucocorticoids (GCs) in cosmetics using dispersive-solid phase extraction (d-SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The analytes were extracted by acetonitrile after dispersing with water, and then purified using the C18 and primary secondary amine (PSA). The chromatographic separations were performed on a Poroshell 120 PFP column (100 mm×2.1 mm, 2.7 μ m) under multiple chromatographic retention modes. Acetonitrile and 0.2% (v/v) acetic acid aqueous solution were used as mobile phases with gradient elution, and all the 10 groups of isomers were baseline separated. The qualitative identification and quantitative analysis of the 81 GCs were operated in the electrospray ionization positive mode using dynamic multiple reaction monitoring (DMRM). The 81 GCs finally were quantified by internal standard method. The correlation coefficients of linear calibration curves were greater than 0.99 in the corresponding mass concentration ranges. The average recoveries of the 81 GCs at three spiked levels ranged from 68.8% to 105.3% with relative standard deviations (RSDs) of 2.9%-13.1% (n=6). The LODs (S/N ≥ 3) and LOQs (S/N ≥ 10) were 0.002-0.006 μ g/g and 0.005-0.020 μ g/g, respectively. A number of 137 cosmetic samples submitted by customers were screened. Sixteen positive samples were found, and the contents of GCs were from 16.9 μ g/g to 158 μ g/g. The results showed that the new method is simple, rapid, sensitive and reliable, and it is suitable for qualitative and quantitative screening analysis of the 81 GCs in cosmetics simultaneously.
A novel method was developed for the simultaneous rapid determination of 81 illegally added glucocorticoids (GCs) in cosmetics using dispersive-solid phase extraction (d-SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The analytes were extracted by acetonitrile after dispersing with water, and then purified using the C18 and primary secondary amine (PSA). The chromatographic separations were performed on a Poroshell 120 PFP column (100 mm×2.1 mm, 2.7 μ m) under multiple chromatographic retention modes. Acetonitrile and 0.2% (v/v) acetic acid aqueous solution were used as mobile phases with gradient elution, and all the 10 groups of isomers were baseline separated. The qualitative identification and quantitative analysis of the 81 GCs were operated in the electrospray ionization positive mode using dynamic multiple reaction monitoring (DMRM). The 81 GCs finally were quantified by internal standard method. The correlation coefficients of linear calibration curves were greater than 0.99 in the corresponding mass concentration ranges. The average recoveries of the 81 GCs at three spiked levels ranged from 68.8% to 105.3% with relative standard deviations (RSDs) of 2.9%-13.1% (n=6). The LODs (S/N ≥ 3) and LOQs (S/N ≥ 10) were 0.002-0.006 μ g/g and 0.005-0.020 μ g/g, respectively. A number of 137 cosmetic samples submitted by customers were screened. Sixteen positive samples were found, and the contents of GCs were from 16.9 μ g/g to 158 μ g/g. The results showed that the new method is simple, rapid, sensitive and reliable, and it is suitable for qualitative and quantitative screening analysis of the 81 GCs in cosmetics simultaneously.
2017, 35(8): 826-831
doi: 10.3724/SP.J.1123.2017.05019
Abstract:
The analytical method of nicotine and cotinine in human urine with hydrophilic interaction chromatography-tandem mass spectrometry (HILIC-MS/MS) was established. After the urine sample containing nicotine-d4 and cotinine-d3 isotope internal standards being diluted with water, the filtrate was introduced into ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for analysis. Separation was performed on an ACQUITY UPLC® BEH HILIC column (50 mm×3.0 mm, 1.7 μ m), in which methanol and 0.1% (v/v) ammonia were used as the mobile phases with isocratic elution at 0.2 mL/min of flow rate. Positive ion scan mode was used for mass spectrometry measurement and calibration curves were plotted for quantification determination. A good linearity could be obtained in the range of 1.0-1000 μ g/L for nicotine and cotinine with the linear coefficients of 0.9949 and 0.9958, respectively. The limits of detection of nicotine and cotinine were 0.082 μ g/L and 0.077 μ g/L, and the limits of quantification were 0.27 μ g/L and 0.26 μ g/L, respectively. The recoveries of the spiked urine samples were 90.4%-103.5% and 93.0%-104.6%, and the relative standard deviations (RSDs) were 4.80%-6.21% and 4.22%-7.15% for nicotine and cotinine respectively. The established method was applied to the analyis of 200 urine samples. Based on the investigation information of the urine of the smoking people, the nicotine contents were 26.68-854.30 μ g/L, and the cotinine contents were 36.66-1191.18 μ g/L (n=86, Mnicotine=76.00 μ g/L, Mcotinine=83.52 μ g/L, M:median); of the nonsmoking people, the nicotine contents were 5.08-69.66 μ g/L, and the cotinine contents were 3.16-28.21 μ g/L (n=114, Mnicotine=7.53 μ g/L, Mcotinine=3.79 μ g/L). The method is simple, sensitive and rapid. It is suitable for batch analysis of nicotine and cotinine in urine, and it can meet the requirement of evaluating the human tobacco exposure.
The analytical method of nicotine and cotinine in human urine with hydrophilic interaction chromatography-tandem mass spectrometry (HILIC-MS/MS) was established. After the urine sample containing nicotine-d4 and cotinine-d3 isotope internal standards being diluted with water, the filtrate was introduced into ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for analysis. Separation was performed on an ACQUITY UPLC® BEH HILIC column (50 mm×3.0 mm, 1.7 μ m), in which methanol and 0.1% (v/v) ammonia were used as the mobile phases with isocratic elution at 0.2 mL/min of flow rate. Positive ion scan mode was used for mass spectrometry measurement and calibration curves were plotted for quantification determination. A good linearity could be obtained in the range of 1.0-1000 μ g/L for nicotine and cotinine with the linear coefficients of 0.9949 and 0.9958, respectively. The limits of detection of nicotine and cotinine were 0.082 μ g/L and 0.077 μ g/L, and the limits of quantification were 0.27 μ g/L and 0.26 μ g/L, respectively. The recoveries of the spiked urine samples were 90.4%-103.5% and 93.0%-104.6%, and the relative standard deviations (RSDs) were 4.80%-6.21% and 4.22%-7.15% for nicotine and cotinine respectively. The established method was applied to the analyis of 200 urine samples. Based on the investigation information of the urine of the smoking people, the nicotine contents were 26.68-854.30 μ g/L, and the cotinine contents were 36.66-1191.18 μ g/L (n=86, Mnicotine=76.00 μ g/L, Mcotinine=83.52 μ g/L, M:median); of the nonsmoking people, the nicotine contents were 5.08-69.66 μ g/L, and the cotinine contents were 3.16-28.21 μ g/L (n=114, Mnicotine=7.53 μ g/L, Mcotinine=3.79 μ g/L). The method is simple, sensitive and rapid. It is suitable for batch analysis of nicotine and cotinine in urine, and it can meet the requirement of evaluating the human tobacco exposure.
2017, 35(8): 832-836
doi: 10.3724/SP.J.1123.2017.04007
Abstract:
A modified high performance liquid chromatographic (HPLC) method was developed for the determination of the five nucleotides (uridine monophosphate (UMP), adenosine monophosphate (AMP), inosine monophosphate (IMP), guanosine monophosphate (GMP) and cytidine monophosphate (CMP)) in infant formula milk powder. The samples were extracted by water, deproteinized by acetic acid and purified with an HLB SPE cartridge. The analytes were separated by a Waters XBrigde Amide column (150 mm×4.6 mm, 3.5 μ m). Acetonitrile, 10 mmol/L sodium dihydrogen phosphate aqueous solution and 0.12%(v/v) phosphoric acid aqueous solution were used as mobile phases with gradient elution. The detection wavelength of photodiode array detector was set at 254 nm. Five linear calibration curves were obtained with correlation coefficients (r2) of 0.9999. The recoveries were determined at three spiked levels ranging from 86.9% to 105.7%. The limits of quantification (LOQs) were from 5.6 mg/kg to 8.0 mg/kg. The intra-day and inter-day precisions were 0.5%-1.7% (n=5) and 0.6%-1.9% (n=9), respectively. The method is simple, effective, accurate and repeatable. It is suitable for thedetermination of the five nucleotides in infant formula milk powder.
A modified high performance liquid chromatographic (HPLC) method was developed for the determination of the five nucleotides (uridine monophosphate (UMP), adenosine monophosphate (AMP), inosine monophosphate (IMP), guanosine monophosphate (GMP) and cytidine monophosphate (CMP)) in infant formula milk powder. The samples were extracted by water, deproteinized by acetic acid and purified with an HLB SPE cartridge. The analytes were separated by a Waters XBrigde Amide column (150 mm×4.6 mm, 3.5 μ m). Acetonitrile, 10 mmol/L sodium dihydrogen phosphate aqueous solution and 0.12%(v/v) phosphoric acid aqueous solution were used as mobile phases with gradient elution. The detection wavelength of photodiode array detector was set at 254 nm. Five linear calibration curves were obtained with correlation coefficients (r2) of 0.9999. The recoveries were determined at three spiked levels ranging from 86.9% to 105.7%. The limits of quantification (LOQs) were from 5.6 mg/kg to 8.0 mg/kg. The intra-day and inter-day precisions were 0.5%-1.7% (n=5) and 0.6%-1.9% (n=9), respectively. The method is simple, effective, accurate and repeatable. It is suitable for thedetermination of the five nucleotides in infant formula milk powder.
2017, 35(8): 837-842
doi: 10.3724/SP.J.1123.2017.04031
Abstract:
A method was developed for the determination of diacetyl in liquors by high performance liquid chromatography-ultraviolet (HPLC-UV) coupled with precolumn derivatization using derivatization reagent 3,3'-diaminobenzidine (DAB). Diacetyl reacted with DAB at room temperature for 10 min. Then the separation was carried out on a high performance liquid chromatograph equipped with a diode array detector (DAD). A Shim-pack VP-ODS (250 mm×4.6 mm, 4.6 μ m) column was employed using water-methanol mobile phases for gradient at a flow rate of 0.7 mL/min and detection wavelength of 254 nm. The method showed a good linearity at diacetyl concentrations from 0.20 μ mol/L to 180 μ mol/L with the correlation coefficient (R2) of 0.999. The limit of detection (S/N=3) and limit of quantification (S/N=10) were 0.09 μ mol/L and 0.20 μ mol/L, respectively. The intra-day precision (RSD) was 1.28% (n=6). The method was further evaluated in the analysis of liquor samples with the recoveries ranging from 92.0% to 103.6% and RSDs from 0.69% to 3.45% (n=3). The method is well suitable for the measurement of diacetyl in liquor samples.
A method was developed for the determination of diacetyl in liquors by high performance liquid chromatography-ultraviolet (HPLC-UV) coupled with precolumn derivatization using derivatization reagent 3,3'-diaminobenzidine (DAB). Diacetyl reacted with DAB at room temperature for 10 min. Then the separation was carried out on a high performance liquid chromatograph equipped with a diode array detector (DAD). A Shim-pack VP-ODS (250 mm×4.6 mm, 4.6 μ m) column was employed using water-methanol mobile phases for gradient at a flow rate of 0.7 mL/min and detection wavelength of 254 nm. The method showed a good linearity at diacetyl concentrations from 0.20 μ mol/L to 180 μ mol/L with the correlation coefficient (R2) of 0.999. The limit of detection (S/N=3) and limit of quantification (S/N=10) were 0.09 μ mol/L and 0.20 μ mol/L, respectively. The intra-day precision (RSD) was 1.28% (n=6). The method was further evaluated in the analysis of liquor samples with the recoveries ranging from 92.0% to 103.6% and RSDs from 0.69% to 3.45% (n=3). The method is well suitable for the measurement of diacetyl in liquor samples.
2017, 35(8): 843-847
doi: 10.3724/SP.J.1123.2017.03045
Abstract:
The contents of Pb2+ in tea was determined by the high performance liquid chromatography (HPLC) method using bis(salicylaldehyde)-o-phenylenediamine (SALOPHEN) as derivatization reagent. The detection wavelength of ultraviolet was 226 nm with Hypersil ODS2 C18 column (250 mm×4.6 mm, 5 μ m) as stationary phase, and pH 10.0 methanol-water (80:20, v/v) as mobile phase. The linear range of Pb2+ was 0.1-30 mg/L and the linear correlation coefficient was 0.9988. The limit of detection was 0.01 mg/L with the recoveries of 91.87%-96.96%. The method has high sensitivity and stability with satisfactory results, which can be used for the detection of Pb2+ in tea samples.
The contents of Pb2+ in tea was determined by the high performance liquid chromatography (HPLC) method using bis(salicylaldehyde)-o-phenylenediamine (SALOPHEN) as derivatization reagent. The detection wavelength of ultraviolet was 226 nm with Hypersil ODS2 C18 column (250 mm×4.6 mm, 5 μ m) as stationary phase, and pH 10.0 methanol-water (80:20, v/v) as mobile phase. The linear range of Pb2+ was 0.1-30 mg/L and the linear correlation coefficient was 0.9988. The limit of detection was 0.01 mg/L with the recoveries of 91.87%-96.96%. The method has high sensitivity and stability with satisfactory results, which can be used for the detection of Pb2+ in tea samples.
2017, 35(8): 848-854
doi: 10.3724/SP.J.1123.2017.04014
Abstract:
The development and optimization of reversed-phase preparative liquid chromatography method for insulin were performed. The chromatographic retention, sample loading and peak broadening were investigated. The mobile phase gradient conditions and stationary phases were optimized. The parameters of the method contained the peak broadening levels under different amounts of sample loading and the concentration distribution of the target compound in the elution curves. The parameters of peak broadening levels were defined and expressed as a matrix, which consisted of sample loading, the forward broadening and the backward broadening levels. The most suitable chromatographic system (including stationary phases and mobile phase conditions) was selected. A gradient program with slow change of the strong elution solvent was used. The most suitable stationary phase should exhibit the narrower peak broadening and the peaks were best to broaden to both sides comparing to that under the analytical conditions. Besides, the concentration distribution of the target compound should be focused on the middle of the elution. The guide principles were validation by purification of crude insulin products. The preparative chromatographic system constructed through this method can remove impurities effectively. The method has good practical value. It can provide reference for the development of preparative chromatographic methods of other macromolecular compounds.
The development and optimization of reversed-phase preparative liquid chromatography method for insulin were performed. The chromatographic retention, sample loading and peak broadening were investigated. The mobile phase gradient conditions and stationary phases were optimized. The parameters of the method contained the peak broadening levels under different amounts of sample loading and the concentration distribution of the target compound in the elution curves. The parameters of peak broadening levels were defined and expressed as a matrix, which consisted of sample loading, the forward broadening and the backward broadening levels. The most suitable chromatographic system (including stationary phases and mobile phase conditions) was selected. A gradient program with slow change of the strong elution solvent was used. The most suitable stationary phase should exhibit the narrower peak broadening and the peaks were best to broaden to both sides comparing to that under the analytical conditions. Besides, the concentration distribution of the target compound should be focused on the middle of the elution. The guide principles were validation by purification of crude insulin products. The preparative chromatographic system constructed through this method can remove impurities effectively. The method has good practical value. It can provide reference for the development of preparative chromatographic methods of other macromolecular compounds.
2017, 35(8): 855-859
doi: 10.3724/SP.J.1123.2017.03001
Abstract:
Home-made asymmetrical flow field-flow fractionation (AF4) system, online coupled with ultraviolet/visible (UV/Vis) detector was employed for the separation and size characterization of low density lipoprotein (LDL) in egg yolk plasma. At close to natural condition of egg yolk, the effects of cross flow rate, sample loading, and type of membrane on the size distribution of LDL were investigated. Under the optimal operation conditions, AF4-UV/Vis provides the size distribution of LDL. Moreover, the precision of AF4-UV/Vis method proposed in this work for the analysis of LDL in egg yolk plasma was evaluated. The intra-day precisions were 1.3% and 1.9% (n=7) and the inter-day precisions were 2.4% and 2.3% (n=7) for the elution peak height and elution peak area of LDL, respectively. Results reveal that AF4-UV/Vis is a useful tool for the separation and size characterization of LDL in egg yolk plasma.
Home-made asymmetrical flow field-flow fractionation (AF4) system, online coupled with ultraviolet/visible (UV/Vis) detector was employed for the separation and size characterization of low density lipoprotein (LDL) in egg yolk plasma. At close to natural condition of egg yolk, the effects of cross flow rate, sample loading, and type of membrane on the size distribution of LDL were investigated. Under the optimal operation conditions, AF4-UV/Vis provides the size distribution of LDL. Moreover, the precision of AF4-UV/Vis method proposed in this work for the analysis of LDL in egg yolk plasma was evaluated. The intra-day precisions were 1.3% and 1.9% (n=7) and the inter-day precisions were 2.4% and 2.3% (n=7) for the elution peak height and elution peak area of LDL, respectively. Results reveal that AF4-UV/Vis is a useful tool for the separation and size characterization of LDL in egg yolk plasma.
2017, 35(8): 860-866
doi: 10.3724/SP.J.1123.2017.03033
Abstract:
A rapid determination method of three pyrethroid pesticides (cyfluthrin, cypermethrin and fenvalerate) in tea was developed by series two-solid phase extraction-column cleanup and external standard method coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) in 30 min. The pesticide residues in tea were extracted with acetonitrile, and cleaned up by Carb/NH2 and SLH solid-phase extraction columns. After filtration, the target compounds were analyzed by GC-MS and quantified by the external standard method. Under the optimized conditions, good linear ranges of 0.05-2.00 mg/kg were obtained. The limits of detection varied from 0.3 to 1.0 μ g/kg. The linear correlation coefficients were greater than 0.999. At three spiked levels (0.10, 0.50 and 2.00 mg/L), the average recoveries were determined between 80.6% and 116.3% in the four matrices. The inter-day relative standard deviations were between 1.3%-12.6%, and the intra-day relative standard deviations were between 2.7% and 12.1%. This method is simple, fast, and has a good reproducibility, which can meet the requirements of the rapid detection of pyrethroid pesticides in tea.
A rapid determination method of three pyrethroid pesticides (cyfluthrin, cypermethrin and fenvalerate) in tea was developed by series two-solid phase extraction-column cleanup and external standard method coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) in 30 min. The pesticide residues in tea were extracted with acetonitrile, and cleaned up by Carb/NH2 and SLH solid-phase extraction columns. After filtration, the target compounds were analyzed by GC-MS and quantified by the external standard method. Under the optimized conditions, good linear ranges of 0.05-2.00 mg/kg were obtained. The limits of detection varied from 0.3 to 1.0 μ g/kg. The linear correlation coefficients were greater than 0.999. At three spiked levels (0.10, 0.50 and 2.00 mg/L), the average recoveries were determined between 80.6% and 116.3% in the four matrices. The inter-day relative standard deviations were between 1.3%-12.6%, and the intra-day relative standard deviations were between 2.7% and 12.1%. This method is simple, fast, and has a good reproducibility, which can meet the requirements of the rapid detection of pyrethroid pesticides in tea.
2017, 35(8): 867-874
doi: 10.3724/SP.J.1123.2017.04002
Abstract:
As coking precursors, aromatic hydrocarbons have an effect on the cracking stability of fuels. A method for identifying and quantitating aromatics in the supercritical cracking products of jet fuel was established by comprehensive two-dimensional gas chromatography coupled with mass spectrometry (GC×GC-MS). The effects of main chromatographic conditions such as initial oven temperature and modulation period on the separation of supercritical cracking products were studied. The method has good separation ability for polycyclic aromatic hydrocarbons (PAH) isomers. A total of 27 aromatics, including monocyclic aromatic hydrocarbons, bicyclic aromatic hydrocarbons, tricyclic aromatic hydrocarbons, tetracyclic aromatic hydrocarbons, etc., were identified based on standard mass spectra, the retention times of standards and literature reports. Moreover, the corresponding quantitative determination was achieved by external standard method of GC×GC-FID. The results showed that the contents of aromatics increased with the increase of gas yield. When gas yield reached 22%, the bicyclic aromatic hydrocarbons began to produce, and their contents increased exponentially with the increase of gas yield. Compared with the traditional GC-MS, the method has better separation and qualitative ability, and can be applied to the separation of complex samples and qualitative and quantitative analyses of cracking products.
As coking precursors, aromatic hydrocarbons have an effect on the cracking stability of fuels. A method for identifying and quantitating aromatics in the supercritical cracking products of jet fuel was established by comprehensive two-dimensional gas chromatography coupled with mass spectrometry (GC×GC-MS). The effects of main chromatographic conditions such as initial oven temperature and modulation period on the separation of supercritical cracking products were studied. The method has good separation ability for polycyclic aromatic hydrocarbons (PAH) isomers. A total of 27 aromatics, including monocyclic aromatic hydrocarbons, bicyclic aromatic hydrocarbons, tricyclic aromatic hydrocarbons, tetracyclic aromatic hydrocarbons, etc., were identified based on standard mass spectra, the retention times of standards and literature reports. Moreover, the corresponding quantitative determination was achieved by external standard method of GC×GC-FID. The results showed that the contents of aromatics increased with the increase of gas yield. When gas yield reached 22%, the bicyclic aromatic hydrocarbons began to produce, and their contents increased exponentially with the increase of gas yield. Compared with the traditional GC-MS, the method has better separation and qualitative ability, and can be applied to the separation of complex samples and qualitative and quantitative analyses of cracking products.
2017, 35(8): 875-880
doi: 10.3724/SP.J.1123.2017.04023
Abstract:
To realize quantitative analysis without authentic standards by gas chromatography, a calculation method of effective carbon numbers (ECNs) was developed by determining the relative response factors of 66 alkanes, alcohols, ethers with GC-FID and studying the relation between ECNs and chemical structures. The correlation coefficient of 0.9998 (N=66) was achieved between theoretical values and experimental values of ECNs. Fifty-seven percent of determined compounds had relative deviations within ±1% and all of them had relative deviations within ±3%. This method is as accurate as common internal-standard method while used in the determination of oxygenated chemicals in gasoline samples, but with far less time and economical cost. It could be used to solve the problem of lacking authentic standards or surrogates.
To realize quantitative analysis without authentic standards by gas chromatography, a calculation method of effective carbon numbers (ECNs) was developed by determining the relative response factors of 66 alkanes, alcohols, ethers with GC-FID and studying the relation between ECNs and chemical structures. The correlation coefficient of 0.9998 (N=66) was achieved between theoretical values and experimental values of ECNs. Fifty-seven percent of determined compounds had relative deviations within ±1% and all of them had relative deviations within ±3%. This method is as accurate as common internal-standard method while used in the determination of oxygenated chemicals in gasoline samples, but with far less time and economical cost. It could be used to solve the problem of lacking authentic standards or surrogates.
2017, 35(8): 881-885
doi: 10.3724/SP.J.1123.2017.04016
Abstract:
A novel method was developed for the determination of methylene bisthiocyanate (MBT) in aquatic products by gas chromatography with pulsed-flame photometric detector (GC-PFPD). The samples were extracted by dichloromethane-n-hexane (1:1, v/v), concentrated and cleaned up by neutral-alumina SPE cartridges. The extracts were eluted with 8 mL dichloromethane, and blown to dryness by nitrogen at 35℃. The final extracts were redissolved with a mixture of dichloromethane-n-hexane (1:1, v/v), separated by an HP-5MS quartz capillary column (30 m×0.32 mm×0.25 μ m) and detected by PFPD with external standard method. Under the optimum experimental conditions, the standard curve was linear in the range of 1.0-20.0 mg/L with correlation coefficient of 0.9971. The limit of detection was 0.1 mg/kg. Recoveries ranged from 65.6% to 97.6% with RSDs of 6.32%-12.8% (n=7). The method has good innovative, advanced and practical values.
A novel method was developed for the determination of methylene bisthiocyanate (MBT) in aquatic products by gas chromatography with pulsed-flame photometric detector (GC-PFPD). The samples were extracted by dichloromethane-n-hexane (1:1, v/v), concentrated and cleaned up by neutral-alumina SPE cartridges. The extracts were eluted with 8 mL dichloromethane, and blown to dryness by nitrogen at 35℃. The final extracts were redissolved with a mixture of dichloromethane-n-hexane (1:1, v/v), separated by an HP-5MS quartz capillary column (30 m×0.32 mm×0.25 μ m) and detected by PFPD with external standard method. Under the optimum experimental conditions, the standard curve was linear in the range of 1.0-20.0 mg/L with correlation coefficient of 0.9971. The limit of detection was 0.1 mg/kg. Recoveries ranged from 65.6% to 97.6% with RSDs of 6.32%-12.8% (n=7). The method has good innovative, advanced and practical values.
2017, 35(8): 886-890
doi: 10.3724/SP.J.1123.2017.04012
Abstract:
A method for screening of acidity regulators in dairy based on ion chromatography-high resolution mass spectrometry technology (IC-HRMS) was set up. The dairy samples were extracted by KOH (pH 7-8) and Oasis MAX SPE column, and separated by a Dionex IonPac AS11-HC column (250 mm×4 mm). All the acidity regulators were detected by Orbitrap full scan mode. Taking six organic acids as an example, the calibration curves showed good linearities in the range of 0.05-5.00 mg/L, and the correlation coefficients (r) were higher than 0.99. By detecting the spiked samples, the recoveries were in the range of 74.3%-115.5% with the relative standard deviations (RSDs) between 0.64% and 4.81%. Malic acid, citric acid, lactic acid, succinic acid and adipic acid could be detected by IC-HRMS in the commercial dairy samples. The results indicate that the method is simple, rapid and suitable for the qualitative screening of acidity regulators in dairy products.
A method for screening of acidity regulators in dairy based on ion chromatography-high resolution mass spectrometry technology (IC-HRMS) was set up. The dairy samples were extracted by KOH (pH 7-8) and Oasis MAX SPE column, and separated by a Dionex IonPac AS11-HC column (250 mm×4 mm). All the acidity regulators were detected by Orbitrap full scan mode. Taking six organic acids as an example, the calibration curves showed good linearities in the range of 0.05-5.00 mg/L, and the correlation coefficients (r) were higher than 0.99. By detecting the spiked samples, the recoveries were in the range of 74.3%-115.5% with the relative standard deviations (RSDs) between 0.64% and 4.81%. Malic acid, citric acid, lactic acid, succinic acid and adipic acid could be detected by IC-HRMS in the commercial dairy samples. The results indicate that the method is simple, rapid and suitable for the qualitative screening of acidity regulators in dairy products.
2017, 35(8): 891-896
doi: 10.3724/SP.J.1123.2017.03042
Abstract:
A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the simultaneous determination of 11 mycotoxins in feeds. The samples were extracted with acetonitrile, then cleaned up by multifunctional purification column filler and PRIME HLB solid phase extraction column. The 11 mycotoxins were separated on an Agilent Zorbax SB-C18 column (150 mm×2.1 mm, 3.5 μ m) with gradient elution program, and methanol-5 mmol/L ammonium acetate solution containing 0.1%(v/v) formic acid were used as mobile phases. The target compounds were detected under electrospray ionization (ESI) both in positive and negative modes with multiple reaction monitoring mode, and quantified by internal standard method. The results indicated that the 11 mycotoxins showed good linear relationships in their respective linear ranges, and the correlation coefficients were greater than 0.99. The limits of quantification (LOQs) were between 2.0 and 50.0 μ g/kg. The average recoveries were between 79.3% and 101.6% at three spiked levels (1, 2 and 5 times LOQs) with relative standard deviations (RSDs) of 5.9%-13.2% (n=5). The method is simple, rapid, sensitive, and can be used for the analysis of the 11 mycotoxins in feeds.
A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the simultaneous determination of 11 mycotoxins in feeds. The samples were extracted with acetonitrile, then cleaned up by multifunctional purification column filler and PRIME HLB solid phase extraction column. The 11 mycotoxins were separated on an Agilent Zorbax SB-C18 column (150 mm×2.1 mm, 3.5 μ m) with gradient elution program, and methanol-5 mmol/L ammonium acetate solution containing 0.1%(v/v) formic acid were used as mobile phases. The target compounds were detected under electrospray ionization (ESI) both in positive and negative modes with multiple reaction monitoring mode, and quantified by internal standard method. The results indicated that the 11 mycotoxins showed good linear relationships in their respective linear ranges, and the correlation coefficients were greater than 0.99. The limits of quantification (LOQs) were between 2.0 and 50.0 μ g/kg. The average recoveries were between 79.3% and 101.6% at three spiked levels (1, 2 and 5 times LOQs) with relative standard deviations (RSDs) of 5.9%-13.2% (n=5). The method is simple, rapid, sensitive, and can be used for the analysis of the 11 mycotoxins in feeds.
2017, 35(8): 897-905
doi: 10.3724/SP.J.1123.2017.03038
Abstract:
The determination of antioxidants continues to be interested, since the oxidative damage is thought to be one of the main mechanisms involved in nearly all chronic renal pathologies. A highly sensitive high performance liquid chromatography-electrochemical detection (HPLC-ECD) method was developed for evaluating the antioxidant properties of Salvia miltiorrhiza (Dan Shen). The method was optimized with respect to selectivity and sensitivity. Chromatographic conditions, including mobile phase pH value, buffer concentration, buffer type, organic solvent type, gradient profile and flow rate, were systematically investigated. Low pH value (2.8), low buffer concentration (20 mmol/L NaH2PO4), a shallow water-acetonitrile gradient, and a flow rate of 0.2 mL/min were the determined optimal conditions for the quantitative analysis of aimed five antioxidants from 14 batches of Dan Shen samples. The described method provided a good recovery (>95%), a very wide linear range (up to 104 for all analytes), a good precision (RSDs<4.01%), and a high sensitivity (LOQ of caffeic acid, 1.5 μ g/L). Compared with UV detection, the described ECD method was also more effective for evaluating the antioxidant properties of Dan Shen, as it provided highly selective detection of electro-active antioxidants
The determination of antioxidants continues to be interested, since the oxidative damage is thought to be one of the main mechanisms involved in nearly all chronic renal pathologies. A highly sensitive high performance liquid chromatography-electrochemical detection (HPLC-ECD) method was developed for evaluating the antioxidant properties of Salvia miltiorrhiza (Dan Shen). The method was optimized with respect to selectivity and sensitivity. Chromatographic conditions, including mobile phase pH value, buffer concentration, buffer type, organic solvent type, gradient profile and flow rate, were systematically investigated. Low pH value (2.8), low buffer concentration (20 mmol/L NaH2PO4), a shallow water-acetonitrile gradient, and a flow rate of 0.2 mL/min were the determined optimal conditions for the quantitative analysis of aimed five antioxidants from 14 batches of Dan Shen samples. The described method provided a good recovery (>95%), a very wide linear range (up to 104 for all analytes), a good precision (RSDs<4.01%), and a high sensitivity (LOQ of caffeic acid, 1.5 μ g/L). Compared with UV detection, the described ECD method was also more effective for evaluating the antioxidant properties of Dan Shen, as it provided highly selective detection of electro-active antioxidants
