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Chinese Journal of Chromatography
2018, Vol. 36, No. 7
Online: 08 July 2018

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Applications of in situ derivatization in liquid chromatography and liquid chromatography-mass spectrometry DU Yuanqi, XIAO Xiaohua, LI Gongke 2018, 36 (7):  579-587.  DOI: 10.3724/SP.J.1123.2018.02021 Abstract ( 730 )   [Full Text(HTML)] () PDF (2067KB) ( 267 )   Derivatization is an effective method to analyze substances, in which the analyte is converted into a more suitable form for analysis. As one of the most used pre-column derivatization methods, in situ derivatization can simultaneously extract and derivatize the analyte in a sample matrix, resulting in good efficiency, sensitivity, and selectivity of the analytical method. Recently, in situ derivatization combined with sample pretreatment techniques has been widely used in biological, drug, food, environmental, and cosmetic samples for the analysis of trace amines, aldehydes and ketones, alcohols, phenols, carboxylic acids, and thiols. This review summarizes the reaction types and representative derivatization reagents of in situ derivatization. The applications of in situ derivatization in liquid chromatography (LC) and liquid chromatography-mass spectrometry (LC-MS) analysis are examined. Furthermore, the long-term prospects and potential applications of in situ derivatization are discussed.

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Applications of mass spectrometry-based proteomics in food authentication and quality identification TIAN Yujing, ZHANG Jiukai, CHENG Haiyan, LI Xian, CHEN Ying 2018, 36 (7):  588-598.  DOI: 10.3724/SP.J.1123.2018.01016 Abstract ( 561 )   [Full Text(HTML)] () PDF (1427KB) ( 311 )   Proteomics, as a new research direction in the post-genomics era, has been developing rapidly in recent years and has been applied in many fields, becoming a powerful research tool in food quality identification and safety control. Proteomics opens up a new horizon in food science research. It can not only identify the species of characteristic proteins, but also quantify the response of targeted proteins. Proteomics allows for the dynamic analysis of protein composition and content in samples that vary in species, geographical origin or growth stage. The research methods of proteomics are varied, and mass spectrometry (MS) is one of the most common techniques. This paper introduces the concept, classification, and research technology of proteomics, as well as common protein databases. Applications of MS-based proteomics in food authentication and quality identification were reviewed, including seafood, meat products, dairy products, health food, and value-added food. Furthermore, the future development of proteomics was investigated.

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Construction of a microfluidic chip-based 72 plex single nucleotide polymorphisms ancestry inference system REN Ping, LIU Jing, LIN Risheng, LIU Yang, HUANG Meisha, HU Sheng, XU Youchun, LI Caixia 2018, 36 (7):  599-607.  DOI: 10.3724/SP.J.1123.2018.01003 Abstract ( 327 )   [Full Text(HTML)] () PDF (1067KB) ( 111 )   The aim was to develop an autosomal single nucleotide polymorphism (SNP) multiplex detection chip system for the inference of the ancestry of unknown individuals. On the basis of the 74-ancestry informative SNP (AISNP) panel screened by our group, a multiplex SNP amplification and detection system, based on a microfluidic chip of competitive allele-specific polymerase chain reaction (PCR), was constructed. The allele-specific primers of each SNP were positioned into a single well on the microfluidic chip and each chip included 112 wells. For detection of SNPs, the chip was placed on the plate thermocycler to perform PCR. The fluorescence signal of the reaction in each well was detected by a confocal laser scanning instrument to evaluate the SNP genotypes of each sample. Fifty-two samples were used for SNP typing. The accuracy of typing results was 100%. Taking 3628 samples of 57 populations as the reference population database, the ancestry of 20 samples was inferred. The results were consistent with the actual sources of the samples. The autosomal 72-SNP microfluidic chip system established can accurately detect SNPs. The ancestry of tested individuals can be accurately inferred from the reference database.

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Preparation and application of magnetic reversed-phase restricted access material WU Shanshan, WEI Chanling, ZHAO Lijuan, TIAN Yang, WANG Fuqiang, GONG Bolin 2018, 36 (7):  608-614.  DOI: 10.3724/SP.J.1123.2018.01040 Abstract ( 377 )   [Full Text(HTML)] () PDF (2745KB) ( 105 )   Using magnetic silica (Fe2O3@SiO2) as the matrix material, a magnetic reversed-phase restricted access material was prepared via surface-initiation atom transfer radical polymerization (SI-ATRP) on the surface of modified Fe2O3@SiO2. Stearyl methacrylate (SMA) was grafted on the inner surface of the modified Fe2O3@SiO2, and glycidylmethacrylate (GMA) was grafted on the outer surface of the modified Fe2O3@SiO2. The magnetic reversed-phase restricted access material was prepared via acid hydrolysis. This material was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and elemental analysis. The exclusion ability of the opened magnetic reversed-phase restricted access material to bovine serum albumin (BSA) was 90.4%. The maximum adsorbed amounts of sulfisoxazole (SIZ), sulfadimethoxine (SDM), trimethoprim (TMP) and sulfamerazine (SMR) were 2.76, 2.24, 1.51 and 1.34 mg/g, respectively. This material was applied to extract and enrich SIZ, SMR and SDM in milk and bovine serum samples. The spiked recoveries of SIZ, SMR and SDM were 88.7%-90.8%, and the relative standard deviations were 3.3%-5.3%. Thus, the magnetic phase restricted access material can simplify the pretreatment of biological matrix samples, and can be applied to the analysis and detection of blood samples or food samples.

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Methylamidation and normal phase chromatography with silica-hydride-based stationary phase for N-glycosylation characterization of monoclonal antibody drugs WANG Yao, LIANG Gaodao, HAN Qing, HU Xun, ZHANG Qiwei, HE Zhenyu 2018, 36 (7):  615-620.  DOI: 10.3724/SP.J.1123.2018.01026 Abstract ( 309 )   [Full Text(HTML)] () PDF (2060KB) ( 89 )   Monoclonal antibodies (mAbs) are efficacious therapeutic agents against various complex diseases. N-glycosylation characterization of mAbs is based primarily on fluorescence derivatization coupled with hydrophilic interaction liquid chromatography (HILIC). However, this method has some drawbacks. Presently, the N-glycosylation of mAbs was analyzed by methylamidation and silica-hydride-based normal phase chromatography (SiH-NPC). Samples were analyzed by liquid chromatography-mass spectrometry after enzymatic cleavage, methylamidation, and purification. SiH-NPC had some advantages compared to HILIC. It offered a novel separation mechanism that allowed for high resolution using salt-free mobile phases, avoiding contamination of the mass spectrometer. SiH-NPC may be applicable for rapid analysis. Its structure was more stable than that of HILIC, and it provided a long service life. In combination with the sialic acid derivatization, SiH-NPC presented a significant advantage in the analysis of sialylated glycans as well as isomeric oligosaccharides by liquid chromatography-mass spectrometry. The approach has potential applications in the biopharmaceutical industry.

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Simultaneous determination of 18 food-borne stimulant drug residues in beef using ultra-high performance liquid chromatography-tandem mass spectrometry QI Heming, HAN Shen, LÜ Meiling, YIN Zhiqiang, YAN Hua, LI Jianhui, CUI Fengyun 2018, 36 (7):  621-628.  DOI: 10.3724/SP.J.1123.2018.01024 Abstract ( 466 )   [Full Text(HTML)] () PDF (2385KB) ( 87 )   A method for the simultaneous determination of 18 food-borne stimulant drug residues in beef was developed based on ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The beef sample was extracted with acidified acetonitrile, cleaned up by Captiva filtration cartridge. The extract was dried with anhydrous magnesium sulfate, and then concentrated by nitrogen flow. The obtained residue was re-dissolved in methanol-water (7:3, v/v). The separation was performed on an Agilent Zorbax Phenyl-Hexyl column with 5 mmol/L ammonium acetate solution (containing 0.01% (v/v) acetic acid) and methanol-acetonitrile (7:3, v/v) as mobile phases with gradient elution. The analyte was detected in positive and negative ion modes and the multiple reaction monitoring (MRM) mode. The quantification analysis was performed by external standard method using matrix-matched calibration curves. The method was linear with the correlation coefficients (R2) ≥ 0.9950 in the range of 0.10-50 μg/L. At the spiked levels of 0.4, 1.0 and 2.0 μg/kg, the recoveries of all compounds ranged from 57.3% to 117.5%, with RSDs in range of 3.1%-15.6% (n=5). The limits of detection and limits of quantification were in the range of 0.0006-0.0900 μg/kg and 0.0020-0.3000 μg/kg, respectively. The method is simple, rapid, accurate and sensitive, and can meet the requirement for the determination of the 18 food-borne stimulant drug residues in beef.

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Determination of fipronil and its metabolites in feeds by stable isotope dilution ultra high performance liquid chromatography-tandem mass spectrometry ZHOU Peng, HUANG Qian, OUYANG Liqun, WANG Zheng, MENG Peng, DAI Ming, WANG Ying 2018, 36 (7):  629-633.  DOI: 10.3724/SP.J.1123.2018.01049 Abstract ( 373 )   [Full Text(HTML)] () PDF (844KB) ( 68 )   A method based on ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was established for the determination of fipronil and its metabolites in feeds. Sodium chloride was added to the samples after the ultrasonic extraction of pure water and acetonitrile, and then cleaned up by the QuEChERS method. The target analytes were separated on a Waters HSS T3 C18 column using methanol and water as mobile phases with gradient elution, and detected by a MS/MS system under negative electro-spry ionization (ESI-) and the multiple reaction monitoring (MRM) mode. The limits of detection (LODs) were 0.05 μg/kg, and the limits of quantification (LOQs) were 0.2 μg/kg. The linear correlation coefficients were more than 0.9998. The average recoveries ranged from 92.3% to 105.4% with RSDs no more than 2.3%. This method is suitable for the identification of fipronil and its metabolites in feeds because of its simplicity and high sensitivity.

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Rapid determination of 48 contaminant residues in food contact plastic products by ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry coupled with microwave-assisted extraction ZHANG Xianchen, ZHANG Pengjie, SHI Chengyu, HUA Hongbo, RONG Yutang, LU Junwen, YANG Fang 2018, 36 (7):  634-642.  DOI: 10.3724/SP.J.1123.2018.01047 Abstract ( 379 )   [Full Text(HTML)] () PDF (5001KB) ( 157 )   An ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry (UPLC-Q Orbitrap HRMS) method was developed for the rapid determination of 48 contaminant residues in food plastic packaging materials. The samples were extracted with methanol using microwave-assisted extraction. The separation of the 48 contaminants was performed on a CAPCELL PAK MG Ⅱ C18 column (150 mm×2.0 mm, 5 μm) with gradient elution. Methanol (containing 0.04% (v/v) formic acid) and water (containing 0.04% (v/v) formic acid and 20 mmol/L ammonium acetate) were used as mobile phases. The compounds were detected under the full scan/date dependent-MS/MS (Full MS/dd-MS2) mode with a heated electrospray ionization (HESI) source. The calibration curves were linear with correlation coefficients no less than 0.9950. The limits of detection (LODs) ranged from 0.1 to 1.0 μg/kg. The average spiked recoveries of the 48 target compounds were between 71.2% and 108.8%, with relative standard derivations (RSDs) ranging from 2.2% to 11.8% (n=6). Compared to previous methods, this method has advantages of simpler sample preparation and higher sensitivity.

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Rapid determination of 66 antibiotics in cosmetics using ultra high performance liquid chromatography-linear ion trap/Orbitrap mass spectrometry LI Hongying, SHEN Huadan, FANG Jiangji, ZHANG Jingya, DING Xiaoping 2018, 36 (7):  643-650.  DOI: 10.3724/SP.J.1123.2018.01041 Abstract ( 335 )   [Full Text(HTML)] () PDF (927KB) ( 96 )   A rapid screening and determination method, in conjunction with a database for confirmation, was established based on 66 antibiotic compounds using ultra-high performance liquid chromatography-linear ion trap/Orbitrap high resolution mass spectrometry (UPLC-LTQ/Orbitrap MS). The analytes were extracted with acetonitrile using ultrasonic extraction. The separation was performed on a C18 column (100 mm×2.1 mm, 1.8 μm) with a gradient elution of 0.1% (v/v) formic acid and acetonitrile. The retention time and accurate mass of the precursor ion were used for rapid screening in positive ionization mode, with the fragment ions obtained by higher energy collisional dissociation used for confirmation. The results indicated that each compound showed good linearity with a correlation coefficient of R2>0.99. The limits of detection (LODs) were in the range 2-4 μg/kg, and the limits of quantification (LOQs) were in the range 5-10 μg/kg. The average recoveries at three levels (1LOQ, 10LOQ, and 30LOQ) were between 58.2% and 119.1%, and the relative standard deviations (RSDs) were between 1.03% and 11.9%. The method is simple, rapid, reliable, and accurate, which is suitable for rapid screening and determination of the 66 antibiotic compounds in cosmetics.

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Determination of maleic hydrazide and its glucosides in tobacco leaves using hydrophilic interaction liquid chromatography-tandem mass spectrometry PANG Tao, LIN Qian, LI Yong, SHI Junli, DENG Xiaopeng, KONG Guanghui, LU Xiuping, JIN Yan 2018, 36 (7):  651-658.  DOI: 10.3724/SP.J.1123.2018.01050 Abstract ( 343 )   [Full Text(HTML)] () PDF (935KB) ( 78 )   A hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method was established for the simultaneous determination of maleic hydrazide (MH) and its two glucosides in tobacco leaves. Ultrasonic assisted extraction of MH and its glucosides was performed using acetonitrile-methyl tert-butyl ether-water (7:10:13, volume ratio). The extraction solution was then centrifuged, and the subnatant was transferred for solvent replacement using acetonitrile. The extract in acetonitrile was then analyzed using HILIC-MS/MS. Method validation was performed, and the linear ranges for MH and MH-O-β -D-glucoside were 5-150 mg/kg with correlation coefficients (r2) greater than 0.9971 for matrix-matched calibration curves. Limits of detection for MH and MH-O-β -D-glucoside were 0.5 mg/kg and 0.3 mg/kg, and limits of quantification were 1.0 mg/kg and 0.8 mg/kg, respectively. The recoveries were in the range of 83.1%-112.3% at three spiked levels (10, 40, 80 mg/kg), with intra-day repeatability of 2.7% and 3.8%, inter-day repeatability of 8.3% and 7.1% at 40 mg/kg. The established method was used for the study of MH metabolism in tobacco leaves. By the 28th day after MH spraying, the content of MH in tobacco leaves had decreased by 80.8%, of which only 7.6% transformed to MH-glucosides. The disposition of the remainder needs to be studied.

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Determination of sulfonylurea herbicide residues in tobacco leaves by molecularly imprinted-solid phase extraction-high performance liquid chromatography ZHENG Yali, GU Lili, SHI Junli, ZHANG Mengxiao, KONG Guanghui, LI Zhijun, HAN Yi, PENG Jian 2018, 36 (7):  659-664.  DOI: 10.3724/SP.J.1123.2018.01010 Abstract ( 497 )   [Full Text(HTML)] () PDF (2737KB) ( 179 )   Molecularly imprinted polymer (MIP) micro-particles were prepared in dichloromethane (DCM) by precipitation polymerization using chlorsulfuron (CS) as a template molecule, α -methacrylic acid (MAA) as a functional monomer, and trimethylolpropane trimethacrylate (TRIM) as a cross-linker. The pretreatment process of the tobacco sample spiked with chlorsulfuron, metsulfuron-methyl, bensulfuron-methyl, tribenuron-methyl, ethametsulfuron, and nicosulfuron, was performed using a chlorsulfuron molecularly imprinted polymer solid phase extraction (CS-MIP-SPE) column prepared with CS-MIP as the sorbent. High performance liquid chromatography (HPLC) was subsequently used for quantitative analysis. In this way, a detection technique for sulfonylurea herbicide residues in tobacco leaves was developed using CS-MIP-SPE as a pretreatment method and HPLC as an analytical tool. The results showed that the methods can be applied to the determination of the six sulfonylurea herbicides in tobacco samples. At spiking contents ranging from 0.50 to 50 μg/g, the recoveries for the six sulfonylurea herbicides in tobacco samples were 77.60%-102.05%, with relative standard deviations of 0.16% to 7.07%, and detection limits of 0.08-0.46 μg/g. With its unique advantages, the MIP-SPE-HPLC method provides a multi-residue analytical platform that can meet the requirements of simultaneous determination of sulfonylurea herbicides in tobacco samples.

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Determination of trace amounts of oxytetracycline in surface water samples by bubble enrichment-high performance liquid chromatography XIONG Fangyong, CAI Yunfeng, ZHANG Ying, DING Jianhua 2018, 36 (7):  665-669.  DOI: 10.3724/SP.J.1123.2018.02003 Abstract ( 341 )   [Full Text(HTML)] () PDF (975KB) ( 75 )   A method was established to determine the trace amounts of oxytetracycline (OTC) in surface water samples by bubble enrichment-high performance liquid chromatography (HPLC). A novel sample pretreatment method, bubble enrichment, was used to enrich trace amounts of oxytetracycline in aqueous solutions, and the effects of bubble enrichment conditions on the enrichment efficiency was investigated. Enrichment factor of oxytetracycline had a maximum of 37.06, RSD was 4.8% (n=11), and LOD was 0.038 mg/L under the optimized conditions of bubble enrichment and chromatography. The method was applied to the determination of oxytetracycline in surface water samples, with an average recovery of 101.9%. It is obvious that bubble enrichment has a positive effect on the enrichment of oxytetracycline, and hence, can be combined with chromatography to realize rapid, sensitive, and accurate detection of oxytetracycline in surface water samples. Additionally, the bubble enrichment method used in this paper does not require any organic solvent for the pretreatment of samples, and furthermore, the device is simple, inexpensive, and easy to operate; therefore, it is a very green sample pretreatment method with great research and promotion value. It is expected to be applicable to the analysis of other trace substances in complex samples.

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Simultaneous determination of 18 fluorescent whitening agents in textiles by ultra performance liquid chromatography TANG Juan, ZHOU Jia, QIAN Kai, DING Youchao, CHENG Yue, QI Yan 2018, 36 (7):  670-677.  DOI: 10.3724/SP.J.1123.2018.01043 Abstract ( 415 )   [Full Text(HTML)] () PDF (902KB) ( 83 )   A method was developed for the simultaneous determination of 18 fluorescent white-ning agents (FWAs) in textiles by ultra performance liquid chromatography with fluorescence detection (UPLC-FLR). The sample was extracted with chloroform-ethanol (6:4, v/v). The separation was performed on an ACQUITY UPLC HSS T3 column (100 mm×2.1 mm, 1.8 μm) with gradient elution. Methanol-water (containing 5 mmol/L ammonium acetate) was used as the mobile phase with a flow rate of 0.4 mL/min. The fluorescence detector was used at 350 nm excitation wavelength and 430 nm emission wavelength. External standard method was used for the quantitative determination. The calibration curves showed good linearity in respective ranges for the 18 FWAs with correlation coefficients (R2) no less than 0.9992. The limits of quantifications (LOQs, S/N=10) were in the range of 0.002-0.1 mg/L. The average recoveries of the 18 FWAs ranged from 88.3% to 104.5% at the different spiked levels with the relative standard deviations (RSDs) of 2.0%-5.5% (n=6). The method has high sensitivity, good precision and accuracy, and is applicable to the determination of all kinds of textiles.

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Simultaneous determination of eight phthalate ester plasticizers in sports beverages using supercritical fluid chromatography WEI Junfang, JIANG Lei, LOU Chaoyan, ZHU Yan 2018, 36 (7):  678-684.  DOI: 10.3724/SP.J.1123.2018.01014 Abstract ( 324 )   [Full Text(HTML)] () PDF (904KB) ( 112 )   Phthalate esters (PAEs) are a group of serious environmental pollutants that are carcinogenic or tumorigenic to humans. In this work, a green, rapid, and effective analytical method based on supercritical fluid chromatography (SFC) has been proposed for the simultaneous determination of the eight PAE plasticizers in sports beverage samples. They are dimethyl phthalate (DMP), diethyl phthalate (DEP), dipropyl phthalate (DPRP), dibutyl phthalate (DBP), dipentyl phthalate (DPP), benzyl butyl phthalate (BBP), di-2-ethylhexyl phthalate (DEHP), and di-n-octyl phthalate (DNOP). Liquid phase extraction (LPE) was employed to extract the PAE plasticizers before testing using SFC with ultraviolet (UV) detection. SFC parameters, including stationary phase screening, modifier composition and volume percentage, column temperature, flow rate, and backpressure, were optimized. Under the optimum conditions, all the eight PAE plasticizers could be determined simultaneously by SFC within 6 min at 225 nm. The optimized eluent was supercritical CO2 with 3% (v/v) methanol. The performance of the developed method was also evaluated. The eight PAE plasticizers exhibited satisfactory linearities with correlation coefficients (r) of 0.9991-0.9997 in the range of 0.05-25 mg/L. The limits of detection ranged from 7.5 to 15 μg/L (S/N=3, n=3). Recoveries of all the PAE plasticizers for the spiked samples ranged from 91.7%-100.2% with relative standard deviations of no more than 6.5% (n=3). This method is green, time-saving, simple, selective, robust, and convenient for the analysis of the eight PAE plasticizers in real sports beverage samples.

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Determination of 20 polychlorinated biphenyls in fish samples by gas chromatography-triple-quadrupole mass spectrometry isotope dilution method CAO Yanping, JIANG Dafeng, LI Fenghua, CHEN Jindong, LI Wei, JIAO Yanni 2018, 36 (7):  685-692.  DOI: 10.3724/SP.J.1123.2018.01022 Abstract ( 417 )   [Full Text(HTML)] () PDF (880KB) ( 114 )   An improved method based on the isotope dilution technique was developed for the determination of 20 polychlorinated biphenyls (PCBs) in fish samples, including seven indicator polychlorinated biphenyls. The analysis was performed by gas chromatography-triple-quadrupole mass spectrometry (GC-MS/MS) in the multiple reaction monitoring (MRM) mode. Two MRM transitions were monitored for each PCB congener for quantitation and qualification purposes. The edible parts of the fish samples were shattered, frozen, and dried. 13C-PCB surrogate standards were spiked into the fish samples. The PCBs in fish samples and the surrogate standards were extracted by auto-Soxhlet extraction. The extract was cleaned-up by a disposable multi-layer column packed with acidic silica gel and basic alumina. 13C-PCB recovery standards were spiked into the extract before injection. The separation was performed on a TG-5MS capillary column. Quantitation was performed by the internal standard method. Every group of PCBs used a same number chlorinated 13C-isotope PCBs congener as the internal standard. The calibration curves of 20 PCB congeners were linear (correlation coefficient (r)>0.99) within the range of 0.05-10 μg/L. For the recovery test, three levels were spiked in matrices. The average recoveries obtained by this method were 80.3%-117.6% and the relative standard deviations (RSDs, n=6) were 5.09%-18.5%. The limits of determination (LODs) were 0.01-0.02 μg/kg. Contents of the 20 PCBs in the fish samples were in the range 1.2-8.8 μg/kg (wet weight), while those of the seven indicator PCBs were in the range 0.68-6.4 μg/kg (wet weight). The method is suitable for determining polychlorinated biphenyls in fish samples.

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Analysis of combustion residue of the typical plastic carrier and accelerant by flash gas chromatography-mass spectrometry ZHANG Jian, LIU Jida 2018, 36 (7):  693-699.  DOI: 10.3724/SP.J.1123.2018.01029 Abstract ( 340 )   [Full Text(HTML)] () PDF (884KB) ( 56 )   A method of fire evidence identification applicable to combustion residue was developed by analyzing the combustion residue of a common plastic carrier and accelerant in a fire field. The method could detect the presence of the accelerant in a fire field, thereby preventing missed identification. The appropriate flash temperature was determined by thermal analysis. The combustion residue of the plastic carrier and accelerant was analyzed by flash technology under the appropriate flash temperature. The application of flash technology was evaluated in terms of a range of different experimental conditions, alongside feasibility and qualitative assessments. We found that the optimum flash evaporation temperature was 300℃ when analyzing the combustion residue corresponding to polyethylene (PE) and polyethylene terephthalate (PET) carrier. Experimental results showed that flash gas chromatography-mass spectrometry (Flash GC-MS) extracted the characteristic residual components of the accelerant and could be used to distinguish whether an accelerant was present in a fire or not. The application of flash evaporation technology to fire evidence identification provides a more complete and accurate analysis of the components of combustion residue, eliminating interference factors. Flash GC-MS enriches the modern fire evidence identification toolkit and can support current methods, leading to more accurate and reliable identification.

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Determination of a new sweetener advantame in food by ultra-high performance liquid chromatography-tandem mass spectrometry WANG Hui, HUANG Xiaobei, LIU Jiang, WANG Ke, GE Fen 2018, 36 (7):  700-704.  DOI: 10.3724/SP.J.1123.2018.01028 Abstract ( 540 )   [Full Text(HTML)] () PDF (862KB) ( 134 )   A new ultra-high performance liquid chromatography-tandem mass spectrometry with triple quadrupole method was developed, and validated for screening and confirmation of the new sweetener advantame in food. The sample was extracted with methanol-water (50:50, v/v), followed by centrifugation. The supernatant was then filtered through a membrane filter. The determinant was performed on Agilent SB-C18 (150 mm×2.1 mm, 5 μm) column with gradient elution. The target compound was carried out by positive electrospray ionization (ESI+) under the multiple reaction monitoring (MRM) mode. While the qualitative screening was achieved with retention time and qualitative ion, the confirmation analysis was achieved with peak area and quantitative ion. The results showed that the limit of detection (LOD, S/N ≥ 3) and the limit of quantification (LOQ, S/N ≥ 10)were 0.03 and 0.10 mg/kg, respectively. The average spiked recoveries showed a variation from 80.3 to 98.0% for the three fortification levels. The results showed good linear relationships in the range of 0.01-1.0 mg/L of advantame with correlation coefficients above 0.997. This procedure was noticeably rapid, simple, sensitive, and accurate. Therefore, this method is suitable for batch determination of the new sweetener advantame in beverages, yogurt, and jelly.