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Chinese Journal of Chromatography
2020, Vol. 38, No. 7
Online: 08 July 2020

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Volume 38, Number 7 Content 2020, 38 (7):  0-0.  Abstract ( 18 )   PDF (6199KB) ( 41 )

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Preface for Special Issue of Separation and Analysis Technologies for Food Safety ZHANG Feng 2020, 38 (7):  731-731.  DOI: 10.3724/SP.J.1123.2020.04022 Abstract ( 42 )   HTML ( 19 )   PDF (991KB) ( 39 )

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Functionalization of carbon dots and their applications in food safety LI Yanqi, WANG Yu, FENG Liang 2020, 38 (7):  732-740.  DOI: 10.3724/SP.J.1123.2019.12003 Abstract ( 223 )   HTML ( 13 )   PDF (2261KB) ( 90 )   Almost two decades have passed since the discovery of carbon nanodots (CDs). As a promising family of optical nanomaterials, CDs have high emission efficiency, excellent water solubility, and good bio-compatibility; in addition, they are inexpensive and can be produced by a facile synthesis process. Because of these advantages, CDs have drawn tremendous attention for use in the development of novel optochemical sensors. However, the application scope of chemical sensors based on pristine CDs is restricted because the synthetic methods and starting materials for the CDs give rise to a great limitation of their surface chemical structures. Therefore, pristine CDs need to be functionalized so that they can be employed in sensing applications, with high sensing capability. Typically, functionalization can be classified into two types: doping and surface modification. Doping, as an effective method for introducing new elements to the skeleton of CDs, not only helps manipulate the energy bang-gap of pristine CDs, but also brings the specific acceptor of the target analyte to the CD matrix. Surface modification is a conventional functionalization method that allows one to manipulate the surface chemical structure of CDs in a covalent or non-covalent fashion, so that the selectivity and sensitivity of pristine CDs can be sequentially improved. In this paper, we review the research progress in the functionalization of CDs over the last eight years based on the publications from Web of Science, and systematically summarize the applications of CD-based sensors in the area of food safety. Although this review is incomprehensive due to space restrictions, it can shed fresh light on the development of CD-based rapid sensors for food safety applications in the near future.

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Research advances in imaging technology for food safety and quality control DENG Yamei, WANG Xiujuan, YANG Minli, HE Muyi, ZHANG Feng 2020, 38 (7):  741-749.  DOI: 10.3724/SP.J.1123.2020.03015 Abstract ( 202 )   HTML ( 12 )   PDF (1672KB) ( 93 )   Food quality and safety are issues of concern to the government, food industry, and consumers; hence, it is imperative to detect harmful substances in foodstuff. Traditional techniques for this purpose include biochemical methods and instrumental analysis methods such as chromatography and chromatography-mass spectrometry. These methods, however, are time-consuming and unable to obtain the spatial distribution of the analytes. Therefore, the development of rapid, non-destructive, real-time, and visual detection technologies has emerged as a hotspot in the field of food research. In recent years, hyperspectral imaging, which combines imaging and spectral technology, is rapidly gaining ground. This technique allows one to determine the geometrical characteristics and chemical composition of samples. Compared with traditional spectral technologies, hyperspectral imaging has the advantages of wide detection ranges, in addition to being real-time and non-destructive. At present, hyperspectral imaging is widely used in meat quality evaluation, detection of adulteration, and meat classification. In addition, Raman imaging is mainly used for the detection of illegal additives in food and for adulteration detection. This technology is fast, non-destructive, and low cost; furthermore, spectral and spatial information of the targets can be simultaneously obtained. Mass spectrometry imaging allows for the visualization and high-throughput analysis of sample tissues, without the need for complex sample preparation steps such as labeling and staining. Compared with other imaging technologies, mass spectrum information of substances can be obtained by mass spectrometry imaging. As a molecular visualized technology, it helps obtain the spatial distribution of nutrients and harmful substances in food. Mass spectrometry imaging has unique advantages in food research, e. g., it is used for molecular-level detection and accurate positioning of substances, and hence, it has excellent application prospects in this field. In this paper, recent literature data about imaging technologies in the field of food research, including 72 reports published in professional local and overseas magazines, are collated. The principles of hyperspectral imaging, Raman imaging, and mass spectrometry imaging are introduced, along with the detailed applications of these methods in the quality detection, source identification, and microbial pollution of food. In addition, it also includes food physical damage, food adulteration and food chemical residues. Besides, the advantages and disadvantages of these imaging technologies are discussed. Finally, prospects for the development of imaging technologies in food research are presented. Future work related to hyperspectral imaging should focus on the development of high-sensitivity cameras and high-resolution systems. Improving the data processing efficiency and adding prediction models are also key points for the future. Future studies on Raman imaging can focus on the application of different chemometrics algorithms that would improve the evaluation of food quality and safety parameters. Expanding the scope of application of these methods in food research will also be the focus of future research. Regarding mass spectrometry imaging, attempts should be made to improve the ionization methods, detection sensitivity, spatial resolution, and data processing effectiveness. Additionally, the combination of spectral imaging and mass spectrometry imaging gives full play to their advantages, so that spectral and mass spectrometry information of the targets can be obtained. In short, the application of imaging technologies in food research is expected to be more promising.

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Research progress on the fragmentation mechanisms of mass spectrometry soft ionization and screening of chemical hazardous substances in food LIU Xiaomin, XU Xiuli, NIE Xuemei, GUO Wei, ZHANG Feng 2020, 38 (7):  750-758.  DOI: 10.3724/SP.J.1123.2020.03002 Abstract ( 99 )   HTML ( 7 )   PDF (1069KB) ( 77 )   Hazardous chemicals in food are an important cause of food safety problems. Mass spectrometry is an effective tool for the qualitative and quantitative analysis of these substances. In this paper, the fragmentation mechanisms for several chemical hazardous substances, including pesticides, veterinary drugs, mycotoxins, and other chemical pollutants classified by structural analogs, are reviewed. For each class of compounds, we summarize the characteristic fragments and neutral loss generated by cleavage in the mass spectrometry analysis. We also summarize the mechanisms applied to screen and discover new structural analogs in food. This review can help researchers analyze and confirm the structure of compounds and provide a theoretical basis for the discovery of new structural analogs in food.

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Progress in analysis methods for major mycotoxins in foodstuffs WU Fengqi, YUE Zhenfeng, ZHANG Yi, HUANG Yuanxiang, WEN Jinglan 2020, 38 (7):  759-767.  DOI: 10.3724/SP.J.1123.2019.11019 Abstract ( 202 )   HTML ( 31 )   PDF (1857KB) ( 102 )   The analysis of mycotoxins in foodstuffs is affected by the complexity of the matrix and the extremely low concentration levels. The development of sample pretreatment and analytical methods that enable highly selective enrichment as well as highly sensitive detection is of great significance for food safety. This paper reviews the recent progress in biotoxin analysis methods and summarizes the prospects and development of this field.

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Research progress on detection of 2-acetyl-1-pyrroline, the characteristic aroma component of fragrant rice HU Yawei, YANG Yang, PENG Jinfeng 2020, 38 (7):  768-774.  DOI: 10.3724/SP.J.1123.2019.12018 Abstract ( 417 )   HTML ( 15 )   PDF (944KB) ( 184 )   2-Acetyl-1-pyrroline (2-AP) has been identified as the characteristic aroma component of fragrant rice, and its concentration determines the quality and price of the rice. However, obtaining accurate assay results with modern analytical instruments remains a major challenge. The two reasons for this setback are the ultralow concentration of 2-AP in samples and the serious interferences in its determination. In natural fragrant rice, the concentration of 2-AP is very low, at the μg/kg level. The interferences mainly originate from the sample matrix or due to co-elution during chromatographic separation. In the present paper, various methods for the sample pretreatment and instrumental analysis of 2-AP in rice are reviewed. The sample pretreatment methods include distillation, extraction, and headspace enrichment procedures. Common instrumental analytical methods include gas chromatography (GC) or GC-mass spectrometry (MS), GC-olfactometry, and derivatization-high performance liquid chromatography-MS/MS developed by the researchers recently. The present review will provide a reference for the determination of 2-AP in the food trade, the research on fragrant rice breeding as well as the management of water and fertilizers in agriculture, and the development of stabilized flavor compounds of fragrant rice scent in food processing.

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Rapid determination of trace ciprofloxacin residue in milk samples using molecularly imprinted membrane extraction-high performance liquid chromatography-tandem mass spectrometry TIAN Hongjing, LIU Tong, YOU Song, ZHANG Feng 2020, 38 (7):  775-781.  DOI: 10.3724/SP.J.1123.2020.02017 Abstract ( 133 )   HTML ( 21 )   PDF (1342KB) ( 87 )   An enrofloxacin (ENR) molecularly imprinted membrane (MIM) was prepared with a polyvinylidenedifluoride (PVDF) membrane as the carrier, ENR as the dummy template molecule, α-methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, and a chloroform-methanol mixture solvent as the porogen. The MIM showed excellent selectivity, high adsorption capacity, and high adsorption rate for ciprofloxacin. Additionally, a method combining molecularly imprinted membrane extraction (MIME) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed and validated for the selective analysis of trace ciprofloxacin residue in milk samples. The sample pretreatment involved only a single step of protein precipitation. Ciprofloxacin showed good linearity in mass concentration range of 0.1-200 μg/L with a high correlation coefficient (r2>0.9996). The limit of detection (LOD, S/N=3) and limit of quantification (LOQ, S/N=10) were 0.02 μg/L and 0.1 μg/L, respectively. The relative standard deviations (RSDs) of interday and intraday precisions ranged from 3.3% to 7.9%. The ciprofloxacin recovery was in the range of 92.6%-119.1%. The results showed that the proposed method is simple and fast, with high accuracy and sensitivity, thus being suitable for the rapid detection of trace ciprofloxacin residue in milk samples.

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Determination of 16 mycotoxins in drug and food homologous products by ultra performance liquid chromatography-tandem mass spectrometry combined with accelerated solvent extraction and QuEChERS FANG Zhen, QU Li, GU Shuqing, CHEN Rouhan, LI You, DENG Xiaojun, GUO Dehua, FENG Feng 2020, 38 (7):  782-790.  DOI: 10.3724/SP.J.1123.2019.10034 Abstract ( 122 )   HTML ( 15 )   PDF (1816KB) ( 94 )   A method was developed for the simultaneous determination of 16 mycotoxins in drug and food homologous products by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) combined with accelerated solvent extraction (ASE) and QuEChERS. The target mycotoxins in drug and food homologous products were extracted by ASE. After concentration, the extracts were purified by QuEChERS. Then, the target compounds were analyzed by UPLC-MS/MS in both positive and negative electrospray ionization and MRM modes. Aflatoxin B1 and fumonisin B1 were quantified by the internal standard method, and the remaining mycotoxins were quantified by the matrix-matched external standard method. The proposed method showed a good linear relationship, with correlation coefficients greater than 0.99. The limits of detection (LODs) and limits of quantification (LOQs) of the 16 mycotoxins ranged from 0.008 μg/kg to 0.3 μg/kg and from 0.03 μg/kg to 1.0 μg/kg, respectively. The blank samples were spiked at three levels, and the recoveries ranged from 70.8% to 118%, with the RSDs being 2.5% to 10.2%. The developed method was successfully applied to mycotoxin analysis in 30 scutellaria, puerarin and sea buckthorn samples bought from local markets. Different levels of mycotoxins were detected in some of the products. The proposed method is simple, rapid and sensitive, and it can be applied to the simultaneous determination of multi-mycotoxins in drug and food homologous products.

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Determination of diazepam in aquatic products by ultra performance liquid chromatography-tandem mass spectrometry with pass-through solid phase extraction SU Shufang, SUN Lizhen, XUE Xia, GONG Pixue, WEI Lili, LI Xinling, ZHU Jianhua, LIU Yanming, ZHANG Feng 2020, 38 (7):  791-797.  DOI: 10.3724/SP.J.1123.2019.11028 Abstract ( 130 )   HTML ( 11 )   PDF (1346KB) ( 87 )   A method was developed for the determination of diazepam in aquatic products by pass-through solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The analyte was extracted with acetonitrile directly and purified on a Prime HLB solid phase extraction column (60 mg/3 mL). The separation was performed on an Acquity UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm)using methanol-0.1% (v/v) formic acid aqueous solution as the mobile phase in gradient elution mode. Qualitative analysis was performed in the multiple reaction monitoring (MRM) mode. The analyte was quantified by matrix-matched external standard curves. The results showed good linear relationship in the range of 0.1-10 ng/mL, and the correlation coefficient (r2) was greater than 0.99. The spiked recoveries of diazepam were 88.2%-101.1% at the spiked levels of 1.5, 3.0 and 15.0 μg/kg, and both the intra-and inter-day precisions were less than 10%. The developed method is simple, rapid and accurate, and it can meet the requirements for diazepam determination in aquatic product samples.

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Determination of 10 pyrethroid pesticide residues in tea by gas chromatography-tandem mass spectrometry coupled with multi-plug filtration cleanup HUANG Yunxia, MENG Zhijuan, ZHAO Limin, SUN Wenyi, WANG Dong, FAN Sufang, LI Qiang, ZHANG Yan 2020, 38 (7):  798-804.  DOI: 10.3724/SP.J.1123.2019.12010 Abstract ( 94 )   HTML ( 8 )   PDF (1365KB) ( 77 )   A method for the determination of 10 pyrethroid pesticide residues in tea was established by multi-plug filtration cleanup (m-PFC) method combined with gas chromatography-tandem mass spectrometry (GC-MS/MS). Different extraction solvents (acetonitrile, acetone and ethyl acetate) and extraction methods (immersion without water and immersion with water) were compared. The effect of two kinds of QuEChERS pipes and m-PFC column on the purification of tea extracts and the pesticide recoveries were compared. The results showed that the tea samples could be extracted most efficiently when using acetonitrile without immersion in water. The m-PFC column had a good purification effect on the tea extract and could guarantee a high recovery rate. Good linear relationships were observed for the 10 pyrethroid pesticides, and the correlation coefficients (R2) were greater than0.9980. The average recoveries for the 10 pyrethroid pesticides were in the range of 87.5%-111.3% at four spiked levels, and the RSDs were in the range of 2.1%-8.9%. The LODs and LOQs were 0.001-0.015 mg/kg and 0.003-0.05 mg/kg, respectively. The method was applied to the determination of the 10 pyrethroid pesticides in 50 tea samples. The detection rate of the pyrethroid pesticides was 48%, but all the pesticide residues were below the national standard limits. Compared with the traditional QuEChERS and solid phase extraction methods, this method has the advantages of operational simplicity as well as high accuracy and good precision. The establishment of this method provides a new strategy for the rapid detection of pyrethroid pesticide residues in tea.

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Non-targeted screening of triazole fungicides in tomatoes by ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry LEI Ruqing, NIU Yumin, GUO Qiaozhen, SHAO Bing, DING Xiaojing 2020, 38 (7):  805-816.  DOI: 10.3724/SP.J.1123.2019.12020 Abstract ( 96 )   HTML ( 7 )   PDF (1229KB) ( 50 )   In order to cope with the differences in international trade regulations, it is necessary to establish a rapid non-targeted screening method for triazole fungicides in food. Therefore, a non-targeted method based on ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was established for the rapid screening of triazole fungicides in tomatoes. Tomato samples were extracted with acetonitrile and then purified by QuEChERS. The purified solution was separated on a BEH C18 column (100 mm×2.1 mm, 1.7 μm) using a gradient mobile phase consisting of acetonitrile and water (both containing 0.1% formic acid). Full information tandem mass spectrometry (MSE) acquisition using electrospray ion source under positive ion mode was performed. The 19 triazole fungicides were divided into eight groups based on their structural differences. The secondary mass fragments of eight typical standards in the eight groups of triazole fungicides were analyzed, and then, the regularities of the characteristic fragment ions and neutral loss fragments produced by collision-induced dissociation of the triazole fungicides were summarized. The fragmentation regularity was further verified by the other 11 triazole fungicides. A total of 16 tomato samples collected from local supermarkets in Beijing were screened using this non-targeted method. Diniconazole was identified and confirmed in one sample, which demonstrated that the method could achieve rapid and accurate non-targeted screening of triazole fungicides in tomatoes. The proposed method is highly efficient, sensitive, and accurate, thus providing a reference for screening triazole fungicide residues in food.

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Simultaneous determination of 37 mycotoxins in grain and animal feed by impurity adsorption purification coupled with ultra-performance liquid chromatography-tandem mass spectrometry WANG Ruiguo, GUO Lili, WANG Peilong, SU Xiao'ou, SONG Zhichao, LIN Gang, ZHU Ronghua 2020, 38 (7):  817-825.  DOI: 10.3724/SP.J.1123.2019.12013 Abstract ( 94 )   HTML ( 8 )   PDF (2452KB) ( 64 )   A rapid method based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS) was developed for the simultaneous determination of 37 mycotoxins having various physicochemical properties in grain and animal feed samples. The 37 analytes were extracted from ground samples with acetonitrile-water-formic acid (84:15.9:0.1, v/v/v) by 20 min vibration, and purified using a commercial MLJ-1 pass-through solid-phase extraction (SPE) clean-up cartridge. The analytes were then separated on a reversed-phase BEH RP18 column by a gradient elution program with 0.1 mmol/L ammonium acetate (containing 0.1% (v/v) formic acid) aqueous solution and 0.1% (v/v) formic acid methanol solution as mobile phases. The separated analytes were detected by MS/MS in the multiple reaction monitoring (MRM) mode via ESI+/- ionization. The results showed that the purification was completed in 1 min and that the 37 analytes could be separated on the chromatographic column in 15 min. The 37 mycotoxins showed a linear relationship within their respective linear ranges, and the correlation coefficients of the matrix-matched calibration curves were greater than 0.98. The average recoveries at four spiked levels (limit of quantification (LOQ), LOQ×5, LOQ×10, LOQ×25) for all the targets except fumonisins ranged from 80% to 120%, with the relative standard deviations (RSDs) lower than 20% (n=6). The limits of quantification (LOQs) for all the analytes were between 2 and 40 μg/kg. The proposed method is simple, fast, and accurate, thus being suitable for detecting multiple mycotoxins in grain and animal feed samples.

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Determination of 18 pesticide residues in environmental water by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry YANG Song, ZOU Nan, GAO Yun, XU Leyuan, ZHANG Wenwen, PAN Canping, MU Wei 2020, 38 (7):  826-832.  DOI: 10.3724/SP.J.1123.2019.12022 Abstract ( 133 )   HTML ( 15 )   PDF (1630KB) ( 86 )   Supporting Information A method was developed for the simultaneous determination of 18 pesticide residues in environmental water by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS). The samples were purified and enriched by a large-volume SPE apparatus through a Cleanrt®-PEP SPE column at a rate of 2 mL/min. After being concentrated 50-fold, the samples were detected by UPLC-MS/MS and quantified by the external standard method. The target compounds showed good linearity in the range of 0.5-50 μg/L, with linear correlation coefficients (R2) ≥0.995. At spiked levels of 10, 100 and 1000 ng/L, the average recoveries of the 18 pesticides in the three different environmental water samples were 71.3%-105.9%, and the relative standard deviations (RSDs, n=5) were 1.3%-9.9%. LOQs of the 18 pesticides were 10 ng/L. The method was applied to the detection of the water environment around Tai'an City, and no pesticide residues were detected at any of the collection sites. The method has the advantages of good purification effect, high versatility, sensitivity, and accuracy, and operational simplicity. The method is suitable for the determination of the 18 pesticides in environmental water.

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Application of isotope dilution-liquid chromatography-tandem mass spectrometry in the preparation and certification of reference material of tenuazonic acid and tentoxin in wheat flour XIE Ji'an, LIU Bolin, ZHAO Ziwei, ZHANG Lei, YANG Dajin, ZHAO Yunfeng 2020, 38 (7):  833-840.  DOI: 10.3724/SP.J.1123.2019.12005 Abstract ( 119 )   HTML ( 13 )   PDF (1020KB) ( 50 )   A method for the preparation and certification of the reference material of tenuazonic acid (TeA) and tentoxin (TEN) in wheat flour was developed. This method provided methodological references to develop of standard material for analyzing alternaria toxins in grains. The wheat flour reference materials were based on wheat grains which were naturally contaminated with alternaria toxins. The certified values for TeA and TEN were determined by isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) and cooperated certification of multiple laboratories. The wheat flour reference materials were stored at room temperature, protected from light and characterized by low uncertainty. The wheat flour reference materials are currently the only wheat flour reference materials that naturally contaminate TeA and TEN, and it can be used in the evaluating related analytical methods involved in food safety risk monitoring, product quality testing and quality control measurements.

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Analysis of nine antioxidants in vegetable oils by high performance liquid chromatography ZHAO Huinan, ZHANG Yanxia, XUE Xia, DAI Kun, ZHENG Wenjing, MA Cheng, ZHU Jianhua, LIU Yanming, ZHANG Feng 2020, 38 (7):  841-846.  DOI: 10.3724/SP.J.1123.2019.11023 Abstract ( 156 )   HTML ( 10 )   PDF (1105KB) ( 101 )   A method was developed for the determination of nine antioxidants in vegetable oils by high performance liquid chromatography (HPLC). The samples were extracted with methanol, and the fat in the samples was degreased by freezing. Separation of the targeted compounds was performed on an XBridge C18 column in gradient elution mode using methanol-0.1% (v/v) formic acid aqueous solution as the mobile phase. The analytes were detected using a diode-array detector by the external standard method. The stability and storage conditions for the nine antioxidants were systematically investigated. Ascorbyl palmitate (AP) was introduced into the preparation and pre-treatment of the targets. The concentration of AP was optimized to improve the stability and recovery of the targets. The effects of different extraction solvents and purification methods on the extraction efficiencies were discussed. The results showed that the nine antioxidants could be separated well under the optimized conditions. Good linear relationships in the linear range were obtained, and the correlation coefficients (R2) were greater than 0.999. The average recoveries of the nine antioxidants ranged from 85.3% to 104.1%, with RSDs of the method ≤5.0%. The limits of quantitation (LOQs) for the nine synthetic antioxidants were in the range of 0.6-3.0 mg/kg. The method is simple, rapid, sensitive, and it shows good recovery and reproducibility.

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Determination of vitamin K1 and vitamin K2 in modulation milk powder by post-column reduction-high performance liquid chromatography SUN Shanshan, GONG Pixue, ZHANG Yanxia, WANG Mingdong, LU Lanxiang, LI Xinling, XUE Xia, LIU Yanming, ZHANG Feng 2020, 38 (7):  847-852.  DOI: 10.3724/SP.J.1123.2019.11020 Abstract ( 140 )   HTML ( 12 )   PDF (1076KB) ( 69 )   A method for the determination of vitamin K1 and vitamin K2 in modulation milk powder was developed by high performance liquid chromatography (HPLC) coupled with post-column reduction. The samples were dissolved in water, lipase hydrolyzed, saponified with 2.5 mol/L sodium hydroxide solution and ethanol solution, extracted with n-hexane, and dissolved in methanol after concentration. The vitamin K were first separated on an Xbridge C18 column and then on a zinc powder reduction column, and detected using a fluorescence detector. The excitation and emission wavelengths were 326 nm and 432 nm, respectively. An external standard method was used for quantification. The results showed that the linearities of vitamin K1 and vitamin K2 was in the ranges of 0.0025-2.0 μg/mL and 0.01-2.0 μg/mL, respectively, with correlation coefficients both greater than 0.999. The spiked recoveries were 80.39%-94.39% and the precisions were 0.85%-3.98%. The limits of detection of vitamin K1 and vitamin K2 were 0.07 μg/100 g and 0.2 μg/100 g, respectively. The limits of quantification of vitamin K1 and vitamin K2 were 0.2 μg/100 g and 0.8 μg/100 g, respectively. The method has high sensitivity and good repeatability, and gives accurate results. It is suitable for the analysis and determination of the vitamin K1 and vitamin K2 in formula milk powder.

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Determination of 32 polychlorinated biphenyls in aquatic products by gas chromatography-high-resolution mass spectrometry with accelerated solvent extraction-purification simultaneously coupled to isotope internal standard method JIANG Feng, YU Tingting, LI Min, RONG Mao, HAN Li, SONG Zhe, ZHU Xiaoling 2020, 38 (7):  853-860.  DOI: 10.3724/SP.J.1123.2019.12006 Abstract ( 84 )   HTML ( 12 )   PDF (1697KB) ( 58 )   Gas chromatography (GC)-high-resolution mass spectrometry (HRMS) with accelerated solvent extraction (ASE)-purification simultaneously coupled to the isotope internal standard method is proposed for the determination of 32 polychlorinated biphenyls (PCBs) in aquatic products. Synchronous purification was achieved by adding 2 g of anhydrous sodium sulfate, 1 g of Cleanert Florisil, and 50 g of neutral alumina as the adsorbent to the ASE system. The PCBs were extracted from aquatic product samples using a dichloromethane-n-hexane (1:1, v/v) mixture at 100 ℃ with two extraction cycles. The extracting solution was purified twice with 0.5 mL concentrated sulfuric acid. After concentration to a constant volume, the target compounds were detected by GC-HRMS and quantified by the isotope internal standard method. Under the optimized conditions, the relative standard deviations (RSDs) of the mean relative response factor (RRF) for the 32 PCBs in the range of 0.1-20 μg/L were less than 15%. The limits of quantification were 0.3-1.9 ng/kg. At three spiked levels (5, 20, and 50 ng/kg) in grass carp and sea bass, the recoveries of the 32 PCBs were between 71.9% and 119.0%, with the RSDs varying from 3.5% to 19.6%. This method effectively reduces the matrix interference and shows high sensitivity, good reproducibility, and stable recovery, thus proving useful for the detection of PCBs in aquatic products.

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Rapid screening of illegally added poppy husk in hot pot sauce and soup by thermal desorption electrospray ionization-triple quadruple mass spectrometry ZHANG Hongyan, SHI Xiaofeng, QIU Guoyu, WANG Xiaoqiao, ZHANG Caixia, ZHANG Xiaoping, WU Fuxiang, XU Xiaohui, LI Chenxi, PAN Xiuli 2020, 38 (7):  861-867.  DOI: 10.3724/SP.J.1123.2020.02002 Abstract ( 87 )   HTML ( 11 )   PDF (1267KB) ( 45 )   A thermal desorption electrospray ionization-triple quadruple mass spectrometry (TD-ESI-MS/MS) method was developed for the rapid screening of poppy husk in hot pot sauce and soup. The solid surface or liquid sample was directly touched by a simple metal probe. The analytes collected on the probe were desorbed and ionized using a TD-ESI source, after which the analyte ions were detected by MS/MS in multiple reaction monitoring (MRM) mode. The results were compared with those of colloidal gold card rapid detection and verified by high performance liquid chromatography coupled with triple quadrupole mass spectrometry (HPLC-MS/MS). The instrument gave the best response with the highest sensitivity under the following conditions: thermal desorption temperature, 260 ℃; injection solvent, 0.1% formic acid aqueous solution containing 10 mmol/L formic ammonium-acetonitrile (1:1, v/v); flow rate, 200 μL/h. The limits of detection (LODs) for papaverine, noscapine, and thebaine in five alkaloids were 2 μg/kg, while those for codeine and morphine were 10 μg/kg in hot pot sauce and 5 μg/kg in soup. The sensitivity of this method was significantly superior to that of the colloidal gold card rapid detection. The method was applied to 50 batches of hot pot sauce and soup. Noscapine, papaverine, thebaine, and morphine were detected in a positive sample of chicken soup, which was consistent with the result of the HPLC-MS/MS method. This method without sample preparation and chromatographic separation is fast, green, and environmentally benign, thus being suitable for the rapid qualitative analysis of poppy husk in food.

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Rapid detection of sulfonamides by heat assisted desorption-dielectric barrier discharge ionization mass spectrometry YE Qian, ZHU Qiumeng, ZHOU Feng, WU Jianping, YAN Feng, ZHAO Peng, WEN Luhong 2020, 38 (7):  868-874.  DOI: 10.3724/SP.J.1123.2020.02019 Abstract ( 79 )   HTML ( 5 )   PDF (1640KB) ( 45 )   Sulfanilamide is a common antibacterial drug that is used in clinical practice and in the industry. However, its abuse has emerged as a serious problem in the aquaculture industry, and more predominantly in the poultry industry, where it is administered for therapeutic purposes or as a growth promoter. In this study, a novel technical platform, heat-assisted desorption-dielectric barrier discharge ionization mass spectrometry (HAD-DBDI-MS), was used to detect sulfanilamide in situ. A method for the rapid identification of five typical sulfanilamide drugs sulfamopyridine, sulfamethoxan, sulfamethoxoline, sulfamidine, and sulfamethoxazole was established after optimizing a series of parameters. Secondary mass spectrometry was used to distinguish the sulfanilamide drugs from one another and from other isomers. Our HAD-DBDI-MS method enhanced the sulfanilamide sensitivities by reducing the limits of detection by about 1-2 orders of magnitude compared to those obtained with the DBDI-MS method. As further research, the profiles of chicken feed with added sulfamopyridine standard as well those of commercial feed with added sulfamidine and sulfamethoxazole were obtained using HAD-DBDI-MS respectively. With the HAD-DBDI-MS method, sulfamopyridine could be directly detected in the complex chicken meat matrix. However, satisfactory results were not obtained when direct HAD-DBDI-MS was used for sulfamidine and sulfamethoxazole detection in the feed matrix. The identification ability was improved when methanol was introduced as the assisting solvent. In this method, chicken feed spiked with sulfamidine and sulfamethoxazole standards were pressed into tablets, and methanol was dropped on the tablet surface. The experimental data indicate that HAD-DBDI-MS is suitable for the rapid identification of sulfanilamide drugs in poultry feed and meat products, thus showing potential value as a detection tool for future application.