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Chinese Journal of Chromatography
2019, Vol. 37, No. 2
Online: 09 February 2019

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Volume 37, Number 2 Content 2019, 37 (2):  0-0.  Abstract ( 147 )   PDF (5472KB) ( 47 )

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Multi-column technologies in chromatographic analysis WANG Xiaofei, SUN Kaiyue, ZHANG Bo 2019, 37 (2):  123-131.  DOI: 10.3724/SP.J.1123.2018.11023 Abstract ( 493 )   [Full Text(HTML)] () PDF (3282KB) ( 258 )   Multi-column chromatographic technologies provide high throughput and high resolution separations through parallel, serial or parallel-serial column combinations. In comparison with classical single-column based chromatography, multi-column chromatography well satisfied the need for separations of large batch samples and highly complex bio-samples, and therefore attracted extensive interests. In this review, we discussed the recent developments in multi-column chromatography and its applications in multidimensional separation, chip chromatography, capillary electrophoresis, stationary-phase screening, and serial column chromatography. We also discussed the limitations and future developments in multi-column chromatography.

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Recent advances in hyphenation of nanoflow liquid phase separation with inductively coupled plasma mass spectrometry DING Fangfang, ZHU Jue, GUO Rui, ZHANG Bo 2019, 37 (2):  132-142.  DOI: 10.3724/SP.J.1123.2018.11025 Abstract ( 297 )   [Full Text(HTML)] () PDF (3093KB) ( 144 )   High-performance nanoflow liquid-phase separation techniques such as nanoflow liquid chromatography (nanoLC), capillary electrophoresis (CE), and microchip chromatography and electrophoresis (chip-ICP-MS) have been hyphenated with inductively coupled plasma mass spectrometry (ICP-MS) extensively. This hyphenation combines the excellent characteristics of the front-end separation technology, such as high selectivity, sensitivity, and speed, and low sample consumption, and the advantages of back-end ICP-MS, such as high resolution, wide dynamic range, and absolute quantification capability. Thus, such hyphenation is becoming an increasingly important analytical tool. Herein we systematically introduce the recent development of hyphenated nanoLC, CE, and chip-ICP-MS, review its application in chemical and biochemical analysis, and discuss potential future developments of hyphenating these technologies.

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Preparation and performance evaluation of a novel polar urea-propyl-C30 stationary phase WEI Min, JIN Xiaoqing, ZHAO Yuexing 2019, 37 (2):  143-148.  DOI: 10.3724/SP.J.1123.2018.09020 Abstract ( 245 )   [Full Text(HTML)] () PDF (3529KB) ( 202 )   A novel polar urea-propyl-C30 (TPU-C30) reversed stationary phase was prepared by using 3-ureidopropyltrimethoxysilane as a coupling agent. The characteristics of TPU-C30 were analyzed by scanning electron microscopy, elemental analysis, infrared spectroscopy and thermal analysis. The results showed that the TPU-C30 stationary phase was successfully prepared. Furthermore, the relative deviations of the element contents of TPU-C30 were within 5% (n=3), which indicated that the proposed synthesis had good repeatability. The chromatographic performances in the stationary phase were evaluated by using different polar compounds, positional isomers and basic compounds as solute probes. Compared to the conventional C18 and C30 columns, the TPU-C30 stationary phase had different selectivity and better shape selection. The TPU-C30 stationary phase can be applied in various fields.

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Determination of coriatin and corianin in plasma and urine using ultra-performance liquid chromatography-triple quadrupole mass spectrometry ZHANG Xiuyao, CAI Xinxin, ZHANG Xiaoyi, LI Ruifen 2019, 37 (2):  149-154.  DOI: 10.3724/SP.J.1123.2018.09025 Abstract ( 313 )   [Full Text(HTML)] () PDF (868KB) ( 65 )   An ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS) method has been developed for the determination of coriatin and corianin in plasma and urine, which are the biomarkers of poisoning caused by Coriaria sinica Maxim. Plasma and urine samples were extracted and purified using a solid supported liquid/liquid extraction method. Chromatographic separation was performed on a Cortecs C18 column (100 mm×2.1 mm, 1.6 μm) using a gradient elution of methanol and water. Coriatin and corianin were detected using negative electrospray ionization tandem mass spectrometry in multiple reaction monitoring (MRM) mode and quantified via a matrix working standard curve internal standard method; florfenicol was used as the internal standard. The assay was linear in the calibration range of 0.03-5.0 μg/L for coriatin and 0.3-50 μg/L for corianin in plasma, and 0.1-10 μg/L and 1-100 μg/L for coriatin and corianin in urine, respectively. The average recoveries were 86.2%-110% for coriatin and corianin in plasma and urine with relative standard deviations of 5.1%-14.6% (n=6). The limits of detection (S/N=3) for coriatin and corianin were 0.01 μg/L and 0.1 μg/L in plasma, and 0.03 μg/L and 0.3 μg/L in urine, respectively. The method is simple, sensitive and accurate for the determination of coriatin and corianin in plasma and urine for toxicological purposes.

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Determination of tracheal cytotoxin in pertussis and diphtheria tetanus acellular pertussis vaccines using liquid chromatography-tandem mass spectrometry LONG Zhen, WEI Chen, GUO Zhimou, MA Xiao, LI Yueqi, YAO Jinting, JI Feng, LI Changkun, HUANG Taohong 2019, 37 (2):  155-161.  DOI: 10.3724/SP.J.1123.2018.08006 Abstract ( 306 )   [Full Text(HTML)] () PDF (1600KB) ( 136 )   Tracheal cytotoxin (TCT) is a toxic glycopeptide, which contribute to the adverse effects of pertussis toxin (PT) and related vaccines. Although pharmacopeias limit the amount of TCT in PT product, there is no recommended TCT determination method in any pharmacopeia. In this study, a liquid chromatography-tandem mass spectrometry method was developed to determine TCT. Chromatographic conditions, including column-type and mobile-phase composition, were optimized. According to the literature reports, both reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC) can provide a good retention for TCT. A large amount of organic solvent is usually used for protein precipitation, which may affect the RPLC mode, leading to peak distortion, while such effects were not observed in HILIC mode. Thus, HILIC mode was used to analyze TCT in this study. The developed method had a wide linear range (5.76-369 ng/L), good precision (no more than 3.9%), satisfied recoveries in various matrices (96.4%-102.5%). The limit of quantification (LOQ) of the developed method was 1279 times lower than the one required by Chinese Pharmacopeia, wherein the required amount of TCT should be less than 2 pmol per dose. The developed method was used to detect TCT in pertussis vaccine (acellular component), pertussis vaccine (acellular, co-purified), co-purified diphtheria tetanus pertussis vaccine, and component diphtheria tetanus acellular pertussis vaccine. As a result, TCT was not detected in any of the selected samples indicating the safety of these vaccines and PT products.

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Simultaneous determination of 120 veterinary antibiotics in meat by combined pretreatment system coupled with ultra-performance liquid chromatography-tandem mass spectrometry BIAN Hua, QIN Yu, YU Chenghua, ZHANG Kai, WANG Chengping, LIN Yikan, YANG Baogang, GE Yu 2019, 37 (2):  162-176.  DOI: 10.3724/SP.J.1123.2018.10003 Abstract ( 316 )   [Full Text(HTML)] () PDF (2051KB) ( 278 )   Supporting Information A comprehensive pretreatment system was developed to simultaneously extract and purify 120 veterinary antibiotics, possessing various physicochemical properties in eight categories. This system was coupled with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the detection of the antibiotics. The samples were dissolved and dispersed by a Na2 EDTA-Mcllvaine buffer, extracted with acetonitrile containing 1.5% (v/v) formic acid, and cleaned using an Oasis PRiME HLB SPE system followed by n-hexane liquid purification. The separation of residue targets was performed on an Atlantis® T3 column (100 mm×2.1 mm, 3 μm) with a gradient elution of 0.1% (v/v) formic acid aqueous solution and acetonitrile as mobile phases and detected by UPLC-MS/MS with the multiple reaction monitoring (MRM) mode via ESI+ ionization. The pH of the extraction solvent and the purification method were optimized to promote the target recoveries. All targets showed good linear ranges from 1.0 to 50.0 μg/L, while all their correlation coefficients (r2) were higher than 0.9953, including r2 values of 89 targets being over 0.9990. The limits of quantification (LOQs) of seven targets were 10.0 μg/kg; 21 targets, 5.0 μg/kg; and the remaining 92 targets, not higher than 2.0 μg/kg. The average recoveries on three spiked levels (low, medium, and high) for all targets ranged from 71.5%-109.2%, with RSD ranging from 0.6%-15.3%. The combined system, exhibiting satisfying recovery and stable repeatability, can be suitably employed for the simultaneous determination of multiple veterinary antibiotics in animal-derived meat products.

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Determination of seven non-selective cyclooxygenase inhibitors in milk powder by ultra-performance liquid chromatography-tandem mass spectrometry with dispersive solid phase extraction LI Jiong, SUN Lan, JIN Mengna, WANG Hongqing, QIU Hongyu 2019, 37 (2):  177-182.  DOI: 10.3724/SP.J.1123.2018.10036 Abstract ( 226 )   [Full Text(HTML)] () PDF (1049KB) ( 55 )   An ultra-performance liquid chromatography-tandem mass spectrometry with dispersive solid phase extraction (dSPE-UPLC-MS/MS) method was developed to determine seven non-selective cyclooxygenase inhibitors in milk powder. The samples were extracted with 0.01 mol/L pH 2.5 ascorbic acid-acetonitrile-ethyl acetate solution (2:5:5, v/v/v), and then purified with a mixture of anhydrous sodium sulfate, octadecyl carbon silica gel (C18-N) sorbent and ethylenediamine-N-propyl carbon silica gel (NH2-PSA) sorbent. The analysis was performed using a UPLC-MS/MS system with Waters CORTECS UPLC C18 (100 mm×2.1 mm, 1.6 μm) column. The mobile phase consisted of 0.1% (v/v) formic acid aqueous solution and acetonitrile containing 0.1% (v/v) formic acid by gradient elution, and the multiple reaction monitoring (MRM) mode was used. Five linear calibration curves were obtained with correlation coefficients (r2) ≥ 0.9965. The recoveries were determined at three spiked levels and ranged from 76.4% to 89.8%. The limits of quantification (LOQs) were from 2 to 5 μg/kg. This method is suitable for the determination of seven non-selective cyclooxygenase inhibitors in milk powder.

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Simultaneous determination of allopurinol, probenecid, benzbromarone in dietary supplements by ultra high performance liquid chromatography-tandem mass spectrometry DENG Xingfei, QI Yan, LI Jinqing, ZHANG Yan, XIONG Bo, LIU Hui 2019, 37 (2):  183-188.  DOI: 10.3724/SP.J.1123.2018.10015 Abstract ( 315 )   [Full Text(HTML)] () PDF (1311KB) ( 143 )   A method based on QuEChERS purification was developed for the simultaneous determination of allopurinol, probenecid and benzbromarone in anti-gout dietary supplements by ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were extracted by acetonitrile mixed with 0.1% (v/v) ammonium hydroxide, and the extracts were purified using primary secondary amine (PSA) and C18 adsorbents. The samples were separated on a C18 chromatographic column with the gradient elution of 0.1% (v/v) formic acid aqueous solution and methanol as mobile phases. The analytes were detected by a electrospray ionization source in the positive or negative ion mode and the multiple reaction monitoring mode. The results showed that the limits of detection of allopurinol, probenecid and benzbromarone were 5, 25 and 25 μg/kg, and the limits of quantification were 17, 80 and 80 μg/kg. The average spiked recoveries of the three chemical drugs in dietary supplements were in the range of 76.8%-116.6% with the relative standard deviations of 2.7%-14.6%. The proposed method was applied for the analysis of 68 dietary supplements, and allopurinol was detected in one of them. This method is simple and sensitive, and can be used for the determination of the allopurinol, probenecid and benzbromarone in anti-gout dietary supplements.

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Determination of acrylamide in coffee by ultra performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry ZHU Mingli, YANG Lizhong, ZHANG Weifeng, CAI Chengyuan, ZHOU Xiangdong 2019, 37 (2):  189-193.  DOI: 10.3724/SP.J.1123.2018.10038 Abstract ( 234 )   [Full Text(HTML)] () PDF (852KB) ( 84 )   A method using ultra high performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (UHPLC-APCI-MS/MS) was developed for the determination of acrylamide in coffee. The coffee samples spiked with 13C3-acrylamide as the internal standard were extracted with methanol, and cleaned using HLB solid phase extraction (SPE) cartridges. The liquid chromatography separation was performed on a Brownlee validated AQ C18 column with isocratic elution. Methanol and 0.1% (volume percentage) formic acid aqueous solution were used as the mobile phase. Identification of acrylamide was achieved by APCI-MS/MS with multiple reaction monitoring (MRM) in the positive mode. The quantification analysis was performed by the internal standard method. The calibration curve showed good linearity with a correlation coefficient of 0.999 in the range of 0.5-100.0 μg/L. The limit of detection (LOD) was 5.0 μg/kg. The limit of quantification (LOQ) was 10.0 μg/kg. Recovery of acrylamide from coffee sample was evaluated at concentrations of 100.0, 200.0 and 1000.0 μg/kg. The average recoveries of acrylamide were between 94.6%-115.0% with relative standard derivations (RSDs) in the range of 2.8%-3.6% (n=6). This simple, accurate and sensitive method was proven to be suitable for the determination of acrylamide in coffee.

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Effects of different processing methods on water soluble polysaccharide contents and monosaccharide compositions in Cervi Cornu Pantotrichum GONG Ruize, WANG Yanhua, QI Yuli, CHEN Lixue, LI Shanshan, SUN Yinshi 2019, 37 (2):  194-200.  DOI: 10.3724/SP.J.1123.2018.10042 Abstract ( 252 )   [Full Text(HTML)] () PDF (1179KB) ( 140 )   The water-soluble polysaccharides in antler velvet were extracted by water extraction and alcohol precipitation. The content was determined by a phenol-sulfuric acid colorimetry. After hydrolysis and derivatization, the various monosaccharide compositions of water-soluble polysaccharides from different parts of the antler velvet after different processing methods were analyzed by ultra high performance liquid chromatography (UPLC). The results showed that the water-soluble polysaccharide contents in wax slices, powder slices, gauze slices and bone slices of the boiled antler velvet were 1.74, 1.67, 1.03 and 1.13 g/kg, respectively, whereas those of the freeze-dried antler velvet were 2.77, 3.07, 1.22 and 3.20 g/kg, respectively. The water-soluble polysaccharide contents in in the same four parts of the antler velvet processed antler velvet without and with blood were 1.55, 1.78, 0.96, 0.77 g/kg, and 1.69, 1.64, 1.01, 1.31 g/kg, respectively. Eight monosaccharides (mannose, glucosamine, ribose, glucuronic acid, galacturonic acid, aminogalactose, glucose and galactose) were detected in the compositions of water-soluble polysaccharides in the antler velvet by using different processing methods. For the same part, the monosaccharide contents in the boiled antler velvet were lower than those in the freeze-dried antler velvet, and the monosaccharide contents (except those of glucosamine and aminogalactose) in the antler velvet processed without blood were lower than those in the antler velvet processed with blood. For different parts processed with the same method, the monosaccharide contents in wax and powder pieces were higher than those in gauze slices and bone pieces. This study provides a theoretical reference for velvet processing and product development.

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Simultaneous determination of chlorogenic acid and cynaroside contents in Lonicerae Japonica Flos by high resolution sampling two-dimensional liquid chromatography WANG Zhicong, FU Rongjie, JI Jianguo, CHEN Bo 2019, 37 (2):  201-206.  DOI: 10.3724/SP.J.1123.2018.10008 Abstract ( 282 )   [Full Text(HTML)] () PDF (2229KB) ( 161 )   An innovative analytical method based on high resolution sampling two-dimensional liquid chromatography (HiRes 2D-LC) was established for determination of chlorogenic acid and cynaroside in Lonicerae Japonica Flos. A C18 column was used in the first dimension (1D)-LC separation with acetonitrile and 0.4% (v/v) phosphoric acid aqueous solution as mobile phases. Five heart cuts of chlorogenic acid and four heart cuts of cynaroside were stored in 2D-LC interface, which was a 5-position-10-port valve equipped with two multiple heart-cutting valves. The stored cuts were sequentially separated in the second dimension (2D)-LC. The 2D separation was carried out on an SB-Phenyl column with acetonitrile and 0.5% (v/v) acetic acid aqueous solution as mobile phases. The results showed that chlorogenic acid peaks in the 1D were well separated, whereas cynaroside peaks in the 1D were co-eluted with interferences. The above two targets were accurately quantified through a high resolution sampling mode based on continuous slice cuts of the whole target peaks. The method had good linearity, recovery and repeatability. The HiRes 2D-LC system could be used to improve separation and quantification of (un)targets in traditional Chinese medicine samples.

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Determination of 10 volatile N-nitrosamines in meat products by gas chromatography-tandem mass spectrometry ZHU Mengmeng, YE Qun, ZHOU Tingting, CHEN Lutao, YU Luping, LI Bin, HU Jinfeng, ZHOU Min 2019, 37 (2):  207-215.  DOI: 10.3724/SP.J.1123.2018.09037 Abstract ( 341 )   [Full Text(HTML)] () PDF (2186KB) ( 195 )   A gas chromatography-tandem mass spectrometry (GC-MS/MS) method was established for the determination of 10 volatile N-nitrosamines in meat products. The meat samples were extracted by simultaneous distillation extraction (SDE), and then a cleanup step involving the frozen fat removal method was applied. The analytes were quantified by the external standard method in multiple reaction monitoring (MRM) mode. Under the optimized conditions, the correlation coefficients of the standard calibration curves were greater than 0.99 in the range of 1.00-1000 μg/L. The limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) were 0.01-0.02 μg/kg and 0.04-0.07 μg/kg, respectively. The average spiked recoveries of the 10 volatile N-nitrosamines were 74.8%-94.3% at spiked levels of LOQ level, 1.0 and 2.0 μg/kg,and the relative standard deviations were less than 8.3%. Six volatile N-nitrosamines (N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosopyrrolidine (NPYR), N-nitrosopiperidine (NPIP), N-nitrosodibutylamine (NDBA) and N-nitrosodi-n-propylamine (NDPA)) were detected in different types of meat products, and each volatile N-nitrosamine in pickled meat products had the highest detection values. The developed method has the advantages of simplicity, sufficient extraction, high sensitivity, and low reagent dosage, in addition to proving suitable for the daily testing requirements of a large number of samples in the laboratory.

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Determination of three volatile N-nitrosamine in drinking water by solid phase extraction and gas chromatography-triple quadrupole mass spectrometry with programmable temperature vaporizer-based large volume injection LI Dengkun, ZHANG Yun, LIU Xiangping, ZHAO Shiquan, CHEN Chunjing, XIONG Lilin 2019, 37 (2):  216-221.  DOI: 10.3724/SP.J.1123.2018.10037 Abstract ( 235 )   [Full Text(HTML)] () PDF (881KB) ( 160 )   A method had been developed for the determination of three N-nitrosamines, namely, N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), and N-nitrosodiethylamine (NDEA) in drinking water by solid phase extraction (SPE) and gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS/MS) with programmable temperature vaporizer (PTV)-based large volume injection (LVI). The N-nitrosamine compounds were extracted from the water sample using a solid phase extraction (SPE) cartridge filled with coconut charcoal, and then eluted with 10 mL methylene chloride. The eluate was dried by anhydrous sodium sulfate and 10 μL was injected into the GC-MS/MS by PTV-LVI. The target compounds were detected by the multi-reaction monitoring (MRM) mode, and quantified with the external standard method. The results showed that the three compounds had good linearities in the range of 1-50 ng/L with correlation coefficients (r2) higher than 0.999. Drinking water samples were spiked with the target compounds at three concentration levels (10, 20, and 50 ng/L), and satisfactory recoveries (between 94.8% and 109%) and good reproductivities (relative standard deviation RSD<10%) were achieved. The limits of quantitation (LOQs) of the three N-nitrosamines were found to be in the range of 0.08-0.7 ng/L. The developed method was sensitive, accurate, convenient, and reliable for the determination of the three trace level N-nitrosamines in drinking water.

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Identification of odorous components in drinking water using headspace-gas chromatography-time-of-flight mass spectrometry JIANG Wanfeng, ZHANG Ning, ZHANG Huizhen 2019, 37 (2):  222-226.  DOI: 10.3724/SP.J.1123.2018.10040 Abstract ( 241 )   [Full Text(HTML)] () PDF (1074KB) ( 77 )   The odorous compounds in drinking water were identified and analyzed by using headspace-gas chromatography-time-of-flight mass spectrometry (HS-GC-TOF-MS) combined with differential analysis software. The number of compounds were reduced by step-by-step screening of mass spectrometry data and statistical analysis of T-test and fold change wherein significant differences in compounds were observed. Further, the structural analysis method was used which revealed that the odorous component present in drinking water is acetaldehyde. The factors such as heating time, heating temperature, sample size, and salt content were optimized by orthogonal test. The limit of detection and limit of quantification were 0.0033 and 0.010 mg/L, respectively. The linear ranges were 0.010 to 0.500 mg/L, and the correlation coefficient was 0.997. Conclusively, the actual water samples were tested, the compounds producing odor were analyzed, and the reasonable suggestions for their production and subsequent processing technology were put forward. The method presented in this study is simple, rapid, sensitive, and is suitable for the identification and analysis of odorous components present in drinking water.

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Determination of propionic acid and its salts in food by gas chromatography LI Xia, LIU Xu, LI Ling, WANG Yanli, TIAN Qiyan, LIU Yanming 2019, 37 (2):  227-232.  DOI: 10.3724/SP.J.1123.2018.09024 Abstract ( 497 )   [Full Text(HTML)] () PDF (1294KB) ( 222 )   A method for the determination of propionic acid and its salts in food by gas chromatography (GC) was developed. Degrease extraction and direct extraction were established for food containing oil and non-oil, respectively. In this study, the effects of different pH values on the solubility and recovery of propionic acid were investigated. The effects of purification conditions, pH values, extraction agent types, and extraction times were studied. After hydrochloric acid solution was added, the pH levels of sample solutions were all found to be less than 2. The sample solutions were degreased with 5 mL n-hexane and extracted twice with 5 mL ethyl acetate. The analytes were detected by GC. The analytes were separated on an HP-INNOWAX chromatographic column and detected by fame ionization detector (FID). The recoveries of degrease extraction were 87.5%-97.6% and relative standard deviation were 3.09%-6.86% (n=6). The recoveries of direct extraction were 90.1%-102.1% and the relative standard deviations were 3.32%-6.33% (n=6). The two methods showed good linearities in the range of 2-1000 mg/L (correlation coefficient is 0.9998). The limit of detection was 0.003 g/kg and the limit of quantification was 0.01 g/kg. The proposed method is accurate, fast, simple, easy, sensitive, and is suitable for the rapid determination of propionic acid and its salts in different food. The proposed method provides a new way for the determination of propionic acid in food.

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Rapid on-site screening of five prohibited ingredients in cosmetics using thermal desorption-corona discharge ionization coupled with ion mobility spectrometry GUO Xiangyu, ZHAI Junfeng, MA Longhua, WU Qing, BAI Hua, MA Qiang 2019, 37 (2):  233-238.  DOI: 10.3724/SP.J.1123.2018.09005 Abstract ( 247 )   [Full Text(HTML)] () PDF (1211KB) ( 81 )   A rapid on-site analytical method is developed for screening lidocaine and four other types of prohibited ingredients in cosmetics using thermal desorption-corona discharge ionization together with ion mobility spectrometry. Performing no pretreatment, we dropped or sprayed cosmetic samples onto a Nomex sampling swab. The sampler was placed into a compartment for thermal desorption and corona discharge ionization; then, ion mobility spectrometry analysis was performed. The limits of detection (LODs) for the five analytes ranged from 10 to 50 ng. The instrumental analysis time for a single run was less than 20 ms, and the total sample analysis period was within 1 min. The proposed method is simple, fast, and has low cost, and could be used as an analytical tool for rapid on-site screening of prohibited ingredients in cosmetics.

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Direct determination of ultra-trace polycyclic aromatic hydrocarbons in water by liquid chromatography coupled with online solid phase extraction WANG Chao, HUANG Zhaozhang, XING Zhanlei, CHEN Ye, YU Jianzhao, LIU Fang, YUAN Mao 2019, 37 (2):  239-245.  DOI: 10.3724/SP.J.1123.2018.09039 Abstract ( 277 )   [Full Text(HTML)] () PDF (689KB) ( 86 )   A method was developed for the direct determination of 16 ultra-trace polycyclic aromatic hydrocarbons (PAHs) in water by liquid chromatography (LC) coupled with online solid phase extraction (online SPE). The water sample was centrifuged at a high speed to remove the particulate matter and prepared into an aqueous solution containing 40% (v/v) methanol. A 2 mL-sample was directly injected into the online SPE flow path. Online purification and enrichment of the samples were carried out on the SPE column (Acclaim PA Ⅱ, 50 mm×4.6 mm, 3 μm). The PAHs eluted from the SPE column were transferred to the analytical flow path by valve switching, and were separated on a Hypersil Green PAHs column (150 mm×3 mm, 3 μm). Water and acetonitrile were used as the mobile phases. The flow rates of 1.0 mL/min and 0.4 mL/min were used in the extraction and balance processes, respectively. The flow rate of 0.6 mL/min was used to separate the PAHs in the analytical flow path. Acenaphthylene without a fluorescent signal was detected at the ultraviolet absorption wavelength of 220 nm, while other PAHs were measured by the fluorescence signal via the special excitation/emission wavelength program. The entire analysis could be completed within 37 min. The linear correlation coefficients of the 16 PAHs were greater than 0.996. The limits of detection of the PAHs were 0.14-12.50 ng/L (S/N=3) with only 0.38 ng/L for benzo(a)pyrene (B(a)P). The recoveries of PAHs at spiked levels of 10, 40 and 200 ng/L in the water samples were 76.1%-134.9%. The RSDs (n=3) were 0.3%-16.6%. Furthermore, the recoveries and RSDs (n=3) of B(a)P were 71.8%-92.7% and 3.9%, respectively. The proposed method is simple, rapid, solvent-saving, stable and sensitive, and can meet the ultra-trace analysis requirements of the PAHs (especially B(a)P) in various water samples.