Chinese Journal of Chromatography

Rapid screening and confirmation of hormones in health foods by high performance liquid chromatography-ion trap-time of flight tandem mass spectrometry

WANG Meiling1, YAN Hongfei1, FU Shanliang1, ZHANG Fan2, YAO Jinting3, DAI Hua1, LI Yongjun1,2*

2012, 30 (10): 980-985. DOI: 10.3724/SP.J.1123.2012.08026

Abstract ( 1548 ) [Full Text(HTML)] ()

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A method was developed for the screening, confirmation and quantification of 21 hormones including progesterones, etrogens, glucocorticoids and resorcylic acid lactones in health foods by high performance liquid chromatography-ion trap-time of flight tandem mass spectrometry (HPLC-IT-TOF-MS). The analytes in the sample were extracted with acetonitrile containing 1.0%(v/v) acetic acid and the extract was purified with the mixed QuEChERS sorbents. In the chromatographic analysis, the 21 target compounds were separated on a C18 column with the gradient elution using the mobile phases of acetonitrile and water containing 0.1% acetic acid. The mass analyzer was performed in positive and negative full scan modes in one injection at the same time. The results showed that the linear ranges of the 21 hormones were 5.0~250 μg/L with the correlation coefficients above 0.993 and the limits of quantification (LOQ, S/N≥10) were 2.0~5.0 μg/kg and 1.0~2.5 μg/L for capsule and oral solution, respectively. The method validation was carried out at three spiked levels, and the recoveries were 60.2%~116.0% with the relative standard deviations (RSDs) of 7.0%~18.3%. The screening of analytes was performed by precision mass matching and library searching. The secondary fragment ion spectra were employed to the confirmation. This method is simple, fast, reliable, and can be applied to the simultaneous screening and determination of hormones in health foods.

Determination of three estrogens in animal liver and kidney tissues by liquid chromatography-tandem mass spectrometry

KANG Haining*, OUYANG Shan, LIN Li, YUE Zhenfeng, SHEN Jincan

2012, 30 (10): 986-990. DOI: 10.3724/SP.J.1123.2012.08027

Abstract ( 1491 ) [Full Text(HTML)] ()

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A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of estrone, 17β-estradiol, estriol in animal liver and kidney tissues. The sample was extracted by tert-butyl methyl ether, and the extract was evaporated by nitrogen at 45 ℃. The residue was redissolved in hexane-dichloromethane (6:4, v/v), then purified on a silica solid-phase extraction column. The eluant was evaporated by nitrogen, dissolved in acetonitrile-water (7:3, v/v) and then analyzed by LC-MS/MS. The separation of estrogens was performed on a Poroshell 120 EC-C18 column with the mobile phases of acetonitrile and water with a gradient elution. The identification and quantification of estrogens were carried out by negative electrospray ionization in the multiple reaction monitoring mode using external standard method. The calibration curves showed good linearity in the range of 1.0~20.0 μg/kg with the correlation coefficients above 0.99. The limit of quantification was 1.0 μg/kg for each estrogen. The average recoveries of the estrogens spiked at 1.0, 2.0, 10.0 μg/kg levels in different matrices were between 70.2% and 114%, and the relative standard deviations were between 2.01% and 14.5%. The method is simple, rapid, sensitive, good in purification effect. It is suitable for the confirmation and quantification of estrogens in animal liver and kidney tissues.

Simultaneous identification and detection of 16 anabolic steroid hormones in muscle using liquid chromatography coupled to quadrupole/linear ion trap mass spectrometry

ZHANG Hongwei1*, CAI Xue1, LIN Liming2, CHEN Liangzhen3, LIANG Chengzhu1, BAO Lei1, TANG Zhixu1, NIU Zengyuan2, WANG Fengmei1

2012, 30 (10): 991-1001. DOI: 10.3724/SP.J.1123.2012.08017

Abstract ( 1628 ) [Full Text(HTML)] ()

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A comprehensive method for simultaneous identification and detection of 16 anabolic steroid hormones (ASs, including andorgens, gestagens and their esters)in muscle samples was developed with liquid chromatography coupled to quadrupole/linear ion trap mass spectrometry (LC-Q/Trap-MS). The ASs in muscle samples were extracted with acetonitrile under ultrasonic assistance. The extract was defatted by n-hexane with liquid-liquid partitioning and followed by clean-up with NH2 solid phase extraction (SPE) cartridge. The separation of analytes was carried out on a CAPCELL PAK C18 MGIII column (150 mm×2.0 mm, 5.0 μm) using mobile phases of 0.1% (v/v) formic acid in acetonitrile and 0.1% (v/v) formic acid-5 mmol/L ammonium formate aqueous solution with gradient elution. A scheduled multiple reaction monitoring (sMRM) in positive mode as survey scan and an enhanced product ion (EPI) scan as dependent scan in an information-dependent acquisition (IDA) experiment was adopted in mass spectrometry acquisition. On-line lab-built MS/MS library and internal standards were employed for the identification and quantification. As a result, the 16 ASs showed good linearity with all correlation coefficients (r) no less than 0.9990 within the linear ranges. The limits of quantification (LOQs, S/N≥10) for the 16 ASs were in the range of 0.029~0.36 μg/kg. At the three spiked levels (0.5, 2.0 and 20 μg/kg), the overall recoveries ranged from 89.9% to 118% with the relative standard deviations (RSDs) no more than 16.2% under within-laboratory reproducibility conditions. The proposed method can be used to identify and detect the 16 ASs in a single run, which makes it effective in residue surveillance of anabolic hormones in muscle samples.

Determination of bisphenol diglycidyl ether residues in canned foodstuffs by high performance liquid chromatography-tandem mass spectrometry

ZHAO Xiaoya*, FU Xiaofang, WANG Peng, LI Jing, HU Xiaozhong

2012, 30 (10): 1002-1007. DOI: 10.3724/SP.J.1123.2012.08024

Abstract ( 1489 ) [Full Text(HTML)] ()

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An accurate quantitative determination and confirmative method for bisphenol diglycidyl ether residues, bisphenol A diglycidyl ether (BADGE), bisphenol F diglycidyl ether (BFDGE), bisphenol A (2,3-dihydroxypropyl)glycidyl ether (BADGE•H2O), bisphenol A bis(2,3-dihydroxypropyl) ether (BADGE•2H2O), bisphenol A (3-chloro-2-hydroxy propyl)(2,3- dihydroxypropyl) ether (BADGE•H2O•HCl), bisphenol A (3-chloro-2-hydroxypropyl)glycidyl ether (BADGE•HCl), bisphenol A bis(3-chloro-2-hydroxypropyl) ether (BADGE•2HCl), bisphenol F bis(2,3-dihydroxypropyl) ether (BFDGE•2H2O), bisphenol F bis(3-chloro-2-hydroxypropyl) ether (BFDGE•2HCl) in canned foodstuffs by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has been established. The sample was extracted with tert-butylmethyl ether and the extract was cleaned-up and concentrated on a Waters Oasis HLB column. The target compounds were analyzed by HPLC-MS/MS on a C18 column by the gradient elution with methanol and 5 mmol/L ammonium acetate containing 0.1% formic acid in a multiple reaction monitoring (MRM) scan mode. External matrix standard solutions were used for the quantitative determination and the calibration curves showed good linearity in the concentration range of 10.0~2000.0 μg/L for the nine target compounds. The limits of quantification of the nine compounds were 10.0 μg/kg (S/N≥10). The average recoveries of the nine compounds ranged from 79.6% to 100.9% at the spiked levels of 10.0, 100.0, 1000.0 μg/kg with the relative standard deviations (RSDs) of 6.3%~12.1%. The method is sensitive, accurate, and suitable for the rapid determination of bisphenol diglycidyl ether residues in canned foodstuffs.

Determination of phenylethanolamine A residue in feeds by ultra performance liquid chromatography-tandem mass spectrometry

SUN Wuyong*, ZHAO Binglin, ZHANG Shoujie, SUN Zhuanlian, ZHANG Li

2012, 30 (10): 1008-1001. DOI: 10.3724/SP.J.1123.2012.08023

Abstract ( 1375 ) [Full Text(HTML)] ()

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A method was developed for the determination of the residue of phenylethanolamine A in feeds by ultra performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS). The phenylethanolamine A in sample was extracted with phosphoric acid methanol solution. The extract was purified and concentrated by an MCX column. In the positive mode, an ultra-performance BEH C18 column (100 mm×2.1 mm, 1.7 μm) was used to separate the phenylethanolamine A, and the separation was carried out on a Waters UPLC system by using gradient elution with acetonitrile and 0.1%(v/v)formic acid aqueous solution as the mobile phases at a flow rate of 0.4 mL/min. The qualitative and quantitative analysis was carried out by multi-reaction monitoring (MRM) mode, in which the analyte was ionized by electrospray ionization interface (ESI). The results showed that, the calibration curve was linear in the range of 0.5~100 μg/kg (r﹥0.999), the limit of quantification (S/N ＞ 10) was 10 μg/kg, the recoveries ranged from 79.6% to 86.2%, and the relative standard deviations (RSDs) were between 3.1% and 6.7%. The real sample tests showed that the method is convenient and reliable.

Determination of six plant growth regulator residues in strawberry by liquid chromatography-quadrupoletime of flight mass spectrometry

LIU Jingjing*, GONG Ping, ZHANG Xiaomei, WANG Jianhua, WANG Jingtang

2012, 30 (10): 1012-1016. DOI: 10.3724/SP.J.1123.2012.08022

Abstract ( 1342 ) [Full Text(HTML)] ()

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A novel method was established for the determination of six plant growth regulators (PGRs), 2,4-dichlorophenoxy acetic (2,4-D), 4-chlorophenoxy-acetic acid (CAP), 4-(3-indolyl)-butyric acid (BAA), forchlorfenuron (CPPU), abscisic acid (ABA) and trans-zeatin (ZT) in strawberry using liquid chromatography-quadrupole-time of flight mass spectrometry (LC-Q TOF MS). The Quick, Easy, Cheap, Effective, Rugged and Safe method (QuEChERS) has been validated for the extraction. In this QuEChERS method, the sample was extracted by acetonitrile and cleaned up with C18 adsorbent. The extract was measured directly by LC-Q TOF MS with electrospray ionization in negative mode. The compounds were separated on an Eclipse XDB-C8 column (150 mm×4.6 mm, 5 μm) with acetonitrile-5 mmol/L ammonium acetate-0.1% formic acid as mobile phase under gradient elution. The confirmatory analysis was carried out by determining the accurate masses of all compounds and fragment ions upon Target MS/MS. The limits of detection (LODs) were between 1 μg/kg and 5 μg/kg. The linear range was 0.005~1.0 mg/L for each analyte. The recoveries ranged from 87% to 107% with the relative standard deviations (RSDs) less than 10% (n=6). The method was proved to be simple and accurate.

Determination of bisphenol A from toys and food contact materials by derivatization and gas chromatography-mass spectrometry

GAO Yonggang1*, ZHANG Yanyan2, GAO Jianguo1, ZHANG Huiling1, ZHENG Lisha1, CHEN Jing1

2012, 30 (10): 1017-1020. DOI: 10.3724/SP.J.1123.2012.08015

Abstract ( 2213 ) [Full Text(HTML)] ()

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A method was developed for the determination of bisphenol A (BPA) in toys and food contact materials. The BPA was extracted with Soxhlet extraction method from the sample and reacted with acetic anhydride. The final product was determined by gas chromatography-mass spectrometry (GC-MS). To achieve the optimum derivatization performance, the derivatization time and dosage of derivatization reagent etc. were investigated. Under the optimized experimental conditions, the final product was stable and the peak shape was good. The linearity of the derivative was good in the range of 0.05 to 50 mg/L with the correlation coefficient (r2) above 0.999. The recoveries ranged from 80% to 93% at the spiked levels of 0.05, 1.00, 10.00 mg/kg with the relative standard deviations (RSDs) less than 3.7%. The limit of detection (S/N=3) was 10 μg/kg. The method is accurate and has high recovery. The method is suitable for the inspection of bisphenol A in toys and food contact materials.

Simultaneous determination of residues of six zeranols in eggs by high performance liquid chromatography with immunoaffinity cleanup column

YOU Lina1, LI Xianliang2,3, XI Cunxian2,3, TANG Bobin2,3, WANG Guomin2,3, ZHANG Lei2,3, YUAN Zhongzhen1, ZHAO Hua1*

2012, 30 (10): 1021-1025. DOI: 10.3724/SP.J.1123.2012.08016

Abstract ( 1721 ) [Full Text(HTML)] ()

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An immunoaffinity cleanup-high performance liquid chromatography (IAC-HPLC) method was established for the simultaneous determination of residues of six zeranols (α-zeranol, β-zeranol, α-zearalenol, β-zearalenol, zearalanone and zearalenone) in eggs. The enzymolyzed samples were extracted with methyl tert-butyl ether, and subsequently reextracted with a sodium hydroxide solution. After the pH value was adjusted to 7, the extract was cleaned up on an immunoaffinity column. The chromatographic separation was performed on an Agilent Eclipse XDB-C18 column (150 mm×4.6 mm, 3.5 μm) using methanol-acetonitrile-water (50:15:35, v/v/v) as the mobile phase at a flow rate of 1.0 mL/min and ultraviolet (UV) detection at 270 nm. The six zeranols had good linear relationships in the range of 0.01~0.2 mg/L with the correlation coefficients not less than 0.9998; the recoveries of six target compounds at different spiked levels ranged from 73.2% to 95.7% and the relative standard deviations were less than 8%. The limit of detection (S/N≥3) was 1.0 μg/kg for each zeranol. The method is stable, reliable and accurate, and can be used for the determination of trace residues of the six zeranols in eggs.

Rapid characterization of impurities in the bulk drug of nifedipine by high performance liquid chromatography-quadrupole time of fight mass spectrometry

ZHU Peixi1, DING Lixia2*, HE Jiajia3, ZHENG Guogang1*

2012, 30 (10): 1026-1030. DOI: 10.3724/SP.J.1123.2012.06022

Abstract ( 1952 ) [Full Text(HTML)] ()

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Four impurities in the bulk drug of nifedipine were detected by means of high performance liquid chromatography coupled with quadrupole time of fight mass spectrometry (HPLC-QTOF MS). A Kromasil C18 HPLC column (250 mm×4.6 mm, 5 μm) was used with methanol-water (60:40, v/v) as mobile phase. The column temperature was maintained at 35 ℃ with an ultraviolet （UV） detection wavelength of 235 nm for analysis. The eluates were detected with a UV detector and a quadrupole time of fight mass spectrometer in positive mode. The sample was infused into the mass spectrometer from the HPLC system through a T-junction with a splitting ratio of 3:1. The ion source temperature was set at 320 ℃ and the electrospray ionization (ESI) needle voltage was always set at 4000 V. Nitrogen was used as the drying gas and nebulizer gas. The protonated molecular ions were selected for determining the structures, and their fragmentation pathways were deduced. Based on the fragmentation behavior of nifedipine, the structures of 3 impurities were identified and one of them was identified as 3-ethyl-5-methyl-2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate, which was an unknown impurity to the best of our knowledge. An other impurity was identified by the comparison of the retention time and tandem mass spectra with the standard substance. The four proposed structures were all confirmed by exact mass evidence. The results indicated that the described method can be effectively applied to perform the identifications in nifedipine and its impurities.

Simultaneous analysis of 19 antibiotics in dairy products using ultra-performance liquid chromatography coupled with high resolution time-of-flight mass spectrometry

ZHANG Jie1, YAN Lijuan2*, PAN Chensong3, LIN Liyi2, ZHANG Xinyi3, SHEN Heqing1*

2012, 30 (10): 1031-1036. DOI: 10.3724/SP.J.1123.2012.06026

Abstract ( 1568 ) [Full Text(HTML)] ()

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An ultra-performance liquid chromatography coupled with high resolution time-of-flight mass spectrometry method (UPLC/HRTOF-MS) has been developed for the simultaneous analysis of 19 antibiotics in dairy products. The sample was treated with acetonitrile and acidic acetonitrile to remove protein and fat, and then the supernatant was concentrated with a concentrator system. The antibiotics in the prepared sample were separated on a BEH column, and then qualitatively and quantitatively analyzed by HRTOF-MS in positive ionization mode within 10 min. A screening database containing the qualitative information of the antibiotics was built with TargetAnalysis software. Matrix matching was used in the antibiotic analysis to compensate for the matrix effects that influence analytical response. The linear range of the antibiotics was 10~500 or 15~1000 μg/L. The limits of detection (LOD) were from 3 to 5 μg/L. At the spiked levels of 20 and 100 μg/L, the average recoveries were from 68.4% to 96.7% with the relative standard deviations ranging from 2.1% to 12.5%. The screening results of a spiked milk sample showed that all the spiked antibiotics could be detected with their deviations of retention time ≤0.1 min, the deviations of mass ＜5 mDa, the degrees of isotope pattern match ≥87.4%, and most spiked antibiotics were detected with high scores. Furthermore, the developed method was applied for the analysis of antibiotics in more than 40 milk and dairy products of seven manufacturers, and the target antibiotics were not detected in all the samples. The method is rapid, sensitive and easy to operate, and is suitable for the screening of antibiotic residues in milk and dairy products.

Development of a gas chromatography-mass spectrometry method for the metabolomic study of rice (Oryza sativa L.) grain

ZHOU Jia, WANG Shuangyuan, CHANG Yuwei, ZHAO Yanni, LU Xin, ZHAO Chunxia, XU Guowang*

2012, 30 (10): 1037-1042. DOI: 10.3724/SP.J.1123.2012.06042

Abstract ( 1579 ) [Full Text(HTML)] ()

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An analytical strategy for the metabolic profiling of rice grain was developed based on gas chromatography-mass spectrometry (GC-MS). For the purpose of obtaining abundant metabolite information, sample preparation step prior to instrumental analysis is necessary to be optimized. D-optimal experimental design was applied to optimize the extraction solvent. Four solvents, including water, methanol, isopropanol and acetonitrile, and their combinations were evaluated for the extraction efficiency using multivariate statistical analysis (partial least square regression). The count of resolved peaks and the sum of peak areas were taken as the evaluation indexes. Methanol/water (80:20, v/v) mixture was highly efficient for rice metabolites and was selected as the suitable solvent formulation. Then, the analytical characteristics of the method were measured. More than 90% of the metabolites had satisfactory precisions, reproducibilities and stabilities (relative standard deviations (RSDs)＜30%). Most of the detected metabolites (about 88.0% of total peak area) showed good linear responses. With the optimized analytical protocol, 315 metabolites were detected in rice and 86 of which were structurally identified by searching in the NIST 08/Wiley standard mass spectral library, covering carbohydrates, amino acids, organic acids, steroids and so on which showed a broad coverage of metabolite data. The established method is expected to be useful for the metabolomic studies of rice.

Determination of 132 pesticide residues in tobacco by gas chromatography-tandem mass spectrometry

CHEN Xiaoshui, BIAN Zhaoyang, TANG Gangling*, HU Qingyuan*

2012, 30 (10): 1043-1055. DOI: 10.3724/SP.J.1123.2012.06031

Abstract ( 1856 ) [Full Text(HTML)] ()

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A simple method for the determination of 132 pesticide residues in tobacco by gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS) was established. The influences of different extraction solvents, different buffer systems and different purifying agents on the recoveries of pesticides were investigated. The tobacco sample was extracted with acetonitrile, then cleaned up by the mixed sorbents of primary secondary amine (PSA) and octadecylsilane (C18E). After dried by nitrogen, the extract residue was reconstituted with n-hexane-acetone (9:1, v/v). GC-MS/MS in multi-reaction monitoring (MRM) mode was used as the detection method and triphenyl phosphate (TPP) as the internal standard. All of the 132 pesticides had good linear relationships (r2 ＞0.99) between 20 μg/kg and 2000 μg/kg. At the three spiked levels of 50, 200 and 500 μg/kg in the tobacco extract, the average recoveries of all the pesticides were in the range of 68.10% to 123.15% except for mirex and hexachlorobenzene; moreover, the relative standard deviations (RSDs) of them were between 1.79% and 19.88%. We participated in the CORESTA (Cooperation Centre for Scientific Research Relative to Tobacco) 2012’s co-experiment. The results of our method and the existed standard methods had good consistency. The accurate, reliable and sensitive method can be applied to the determination of the 132 pesticide residues in tobacco for rapid screening and quantitative analysis.

Simultaneous determination of three aminothiols in human plasma by high performance liquid chromatography with gold nanoparticle enrichment

Xin LU

2012, 30 (10): 1056-1061. DOI: 10.3724/SP.J.1123.2012.05011

Abstract ( 1779 ) [Full Text(HTML)] ()

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A high performance liquid chromatography (HPLC) method with ultraviolet detection (UVD) for the simultaneous determination of cysteine (Cys), homocysteine (Hcys) and glutathione (GSH) in human plasma was established. Tween 20-capped gold nanoparticles (Tween 20-AuNPs) were used as selective probes for the extraction and enrichment of aminothiols. The aminothiols removed from the Tween 20-AuNPs by dithiothreitol were separated on a SpursilTMC18 column (250 mm×4.6 mm, 5 μm) with a mobile phase of 60 mmol/L phosphate buffer solution (pH 2.0). The column eluent was monitored using UVD at the wavelength of 200 nm. The linear ranges were found between peak area and concentration in the ranges of 0.025~350 μmol/L for Cys, 0.02~60 μmol/L for Hcys and 0.01~50 μmol/L for GSH, with linear regression coefficients all above 0.99. The limits of detection (LOD, signal to noise ratio of 3) for the aminothiols were between 2.5 nmol/L and 6.0 nmol/L and the recoveries were between 92.8% and 106.0%. Due to the significant interference reduction of endogenous substances in the plasma and the subsequent improvement of the selectivity and sensitivity of HPLC-UVD, the present method was applied for the simultaneous analysis of the forementioned aminothiols in the plasma samples of cardiovascular disease patients. The results showed that the levels of Hcys and GSH had significant differences between the patients and the controls, while that of Cys had no significant difference.

Separation of purines, pyrimidines, pterins and flavonoids on magnolol-bonded silica gel stationary phase by high performance liquid chromatography

CHEN Hong, LI Laisheng*, ZHANG Yang, ZHOU Rendan

2012, 30 (10): 1062-1067. DOI: 10.3724/SP.J.1123.2012.06028

Abstract ( 1600 ) [Full Text(HTML)] ()

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A new magnolol-bonded silica gel stationary phase (MSP) was used to separate the basic drugs including four purines, eight pyrimidines, four pterins and five flavonoids as polar representative samples by high performance liquid chromatography (HPLC). To clarify the separation mechanism, a commercial ODS column was also tested under the same chromatographic conditions. The high selectivities and fast baseline separations of the above drugs were achieved by using simple mobile phases on MSP. Although there is no end-caped treatment, the peak shapes of basic drugs containing nitrogen such as purines, pyrimidines and pterins were rather symmetrical on MSP, which indicated the the magnolol as ligand with multi-sites could shield the side effect of residual silanol groups on the surface of silica gel. Although somewhat different in the separation resolution, it was found that the elution orders of some drugs were generally similar on both MSP and ODS. The hydrophobic interaction should play a significant role in the separations of the above basic drugs, which was attributed to their reversed-phase property in the nature. However, MSP could provide the additional sites for many polar solutes, which was a rational explanation for the high selectivity of MSP. For example, in the separation of purines, pyrimidines and pterins on MSP, hydrogen-bonding and dipole-dipole interactions played leading roles besides hydrophobic interaction. Some solute molecules (such as mercaptopurine, vitexicarpin) and MSP can form the strong π-π stacking in the separation process. All enhanced the retention and improved the separation selectivity of MSP, which facilitated the separation of the basic drugs.

Determination of paraquat and diquat in drinking water and environmental water by high performance liquid chromatography coupled with on-line clean-up and solid phase extraction

CHEN Jing1, LIU Zhaojin2, AN Baochao1, LU Yan1, XU Qun1*

2012, 30 (10): 1068-1073. DOI: 10.3724/SP.J.1123.2012.06014

Abstract ( 1842 ) [Full Text(HTML)] ()

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An on-line solid phase extraction (SPE) system was used to eliminate the interferences sufficiently and fulfill the simple and sensitive determination of diquat and paraquat in tap and pond water. This on-line SPE system used two SPE cartridges. One was an Acclaim Mixed-Mode WAX-1 cartridge for the elimination of anionic interferences; the other one was an Acclaim Mixed-Mode WCX-1 cartridge for the enrichment of diquat and paraquat and the elimination of co-enriched cationic interferences. The baseline separation of diquat and paraquat was achieved on an Acclaim Trinity P1 column. A dual-gradient high performance liquid chromatographic (HPLC) system provided an efficient platform to fulfill the on-line SPE and separation, and the system operated under automatic control of chromatography data system software. The complete analysis only required 16 min, and the detection limits of the method were 0.12 μg/L for diquat and 0.10 μg/L for paraquat. The method is simple, rapid and sensitive, and can be applied to the determination of diquat and paraquat in drinking water and environmental water.

Simultaneous determination of nine heterocyclic aromatic amines in mutton products by solid phase extraction-high performance liquid chromatography

GUO Haitao, PAN Han, WANG Zhenyu, CHEN Li, ZHANG Dequan*

2012, 30 (10): 1074-1080. DOI: 10.3724/SP.J.1123.2012.06023

Abstract ( 1352 ) [Full Text(HTML)] ()

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method was established for the simultaneous determination of nine heterocyclic aromatic amines (HAAs) in mutton products by solid phase extraction-high performance liquid chromatography (SPE-HPLC). As a result, the sample was prepared by ultrasound in 2 mol/L NaOH, and dichloromethane was selected as the extraction solvent. The extract was purified and concentrated with an MCX SPE column. The chromatographic separation was achieved on a reverse-phase C18 column by gradient elution using 0.01 mol/L phosphoric acid (adjusted to pH 3.6 by triethylamine) and acetonitrile, detected with a diode array detector (DAD) at 228 nm for 2-amino-9H-pyrido［2,3-b］indole (AaC) and 2-amino-3-methyl-9H-pyrido［2,3-b］indole (MeAaC); 253 nm for 2-amino-3-methylimidazo［4,5-f］quinoline (IQ), 1-methyl-9H-pyrido［3,4-b］indole (Harman), 9H-pyrido［3,4-b］indole (Norharman); 263 nm for 2-amino-3,8-dimethylimidazo［4,5-f］quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo［4,5-f］quinoxaline (4,8-DiMeIQx), 3-amino-1-methyl-5H-pyrido［4,3-b］indole (Trp-p-2); 321 nm for 2-amino-1-methyl-6-phenylimidazo［4,5-b］pyridine (PhIP). The results showed that the nine HAAs can be separated efficiently. The recoveries (n=6) of the nine HAAs spiked in meat were between 50.27% and 94.77% with the relative standard deviations of 0.08%~4.42%. The limits of detection of this method were 1.6~41.0 μg/L for the nine HAAs. The method is simple, accurate, rapid and repeatable. It can be used for the simultaneous determination of the nine HAAs in mutton products.

Thin layer chromatographic separation of cobalt from nickel on impregnated silica gel layers: quantitative determination by digital image analysis

P A MOHAMED NAJAR*, R G SONALI, M T NIMJE, K V RAMANA RAO

2012, 30 (10): 1081-1088. DOI: 10.3724/SP.J.1123.2012.05030

Abstract ( 1428 ) [Full Text(HTML)] ()

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Thin layer chromatography (TLC) of cobalt and nickel has been performed on silica gel layers induced with alkali mediated cellulose extract. A novel combination of 10% aqueous solutions of Tween-20 and potassium thiocyanate in 1∶1 (v/v) was identified as the best mobile phase for the selective separation of Co2+from Ni2+on the impregnated Silica Gel G layers. The chromatographic characteristics of the cations were studied and the limits of detection as well as the limits of quantification for Co2+and Ni2+were determined. The quantitative estimation of the cations was achieved from the digital image analysis of respective chromatograms. The proposed quantitative method was successfully applied with 0-0.50% error for the determination of Co2+from Ni2+in spiked samples of bauxite, soil and rock containing common cations such as Al3+, Fe2+, Ti4+, Zn2+, Mn2+, Cu2+, Cr6+, Mg2+, etc. under the optimized chromatographic conditions.

Determination of amoxicillin in honey by high performance liquid chromatography-tandem mass spectrometry

XU Wei*, ZHANG Xiaoyan, WU Bin, YIN Yao, YANG Wenquan, SHEN Chongyu, DING Tao, CHEN Huilan

2012, 30 (10): 1089-1092. DOI: 10.3724/SP.J.1123.2012.06030

Abstract ( 1731 ) [Full Text(HTML)] ()

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A method for the determination of amoxicillin in honey by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established. The samples were dissolved by phosphate buffer and cleaned-up by solid phase extraction (SPE) cartridge. The analytes were determined by HPLC-MS/MS on a C18 column with methanol and 0.1% (v/v) formic acid solution as mobile phases with gradient elution. The analysis of amoxicillin was performed under selected reaction monitoring mode by selecting one parent ion and two daughter ions as qualitative ions and the most abundant daughter ion as quantitative ion. The external standard was used for quantitative analysis in this method. The calibration curve showed good linearity in the range of 2.0~100.0 μg/L with good precision and accuracy (r2＞0.99). The limit of detection (LOD) and limit of quantitation (LOQ) were 2.0 μg/kg and 5.0 μg/kg, respectively. The average recoveries of amoxicillin in spiked honey ranged from 74.2% to 81.7% with the intra-day precisions (relative standard deviations, RSDs) from 2.8% to 7.8% and the inter-day precisions (RSDs) from 9.1% to 11.3%. This method is convenient and suitable for the determination of amoxicillin in honey.

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