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Chinese Journal of Chromatography
2023, Vol. 41, No. 11
Online: 08 November 2023

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Preface

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Preface for Special Issue of Separation and Analysis for Food Safety-High Resolution Technology ZHANG Feng 2023, 41 (11):  951-951.  DOI: 10.3724/SP.J.1123.2023.10031 Abstract ( 78 )   HTML ( 38 )   PDF (774KB) ( 82 )

Perspective

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Application progress of innovative high resolution separation and analysis technology in food safety detection field SUN Yan, XIE Yun, XU Xiuli, TAN Mingqian, ZHANG Feng 2023, 41 (11):  952-959.  DOI: 10.3724/SP.J.1123.2023.08026 Abstract ( 137 )   HTML ( 45 )   PDF (2275KB) ( 141 )   In the last decade, mass spectrometry (MS) has been widely used in food inspection science, and the continuous improvement of instruments is the key to the breakthrough of analytical chemistry technology. This paper discusses the latest progress and application of high resolution separation and analysis technology in food safety field (2013-2023), focusing on the innovative development technologies such as on-line MS coupling technology, high resolution screening technology and micro mass spectrometer. Finally, the development of new device in the field of food safety detection is prospected.

Articles

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Liquid chromatography-high resolution mass spectrometry analysis of 300 illegally added drugs and their analogues in functional milk powder for the elderly NING Xiao, JIN Shaoming, LI Zhiyuan, YANG Chongjun, MAO Da, CAO Jin 2023, 41 (11):  960-975.  DOI: 10.3724/SP.J.1123.2023.05013 Abstract ( 105 )   HTML ( 25 )   PDF (1915KB) ( 221 )   Supporting Information Various types of milk powder purportedly providing diverse health functions have emerged with the growth of the country’s elderly population. Some manufacturers illegally add chemical drugs to their products to achieve their reported benefits, which poses a threat to consumer health. The existing standard methods are inapplicable to such complex sample matrices and require testing based on functional claims and classification. These limitations not only consume manpower and resources but also seriously impede daily regulatory efforts to detect unknown risk substances. In this study, a high-throughput method for the screening and quantitative analysis of 300 illegally added chemical drugs in functional milk powder and an identification strategy for unknown structural analogues were established using Zeno SWATH® data-independent acquisition (DIA) ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) technology combined with a QuEChERS sample purification method. The QuEChERS purification process was developed according to the characteristics of milk powder matrix. The supernatant was separated on a Kinetex F5 column (100 mm×3.0 mm, 2.6 μm) by gradient elution using 5 mmol/L ammonium formate aqueous solution (0.1% (v/v) formic acid, ) and methanol-acetonitrile (1∶1, v/v) as mobile phases. The method was validated in terms of selectivity, linearity, limits of detection and quantification (LODs and LOQs, respectively), matrix effect, accuracy, and precision. Based on a screening database for the 300 target substances, electron-activated dissociation (EAD) fragmentation was applied to obtain rich secondary MS fragmentation information, and unknown structural analogues were identified and confirmed through fragment attribution analysis. The results indicated that all compounds had good linear relationships in certain ranges with correlation coefficients >0.99. The LODs and LOQs were 0.04-2.7 and 0.2-8.0 μg/kg, respectively. The average recoveries at three spiked levels were in the range of 73.1%-125.2%, and the relative standard deviations were ≤14.8% (n=6). When the developed method was applied to detect illegally added chemicals in 60 functional milk powder samples, it detected benzoguanidine and sildenafil and successfully identified ethylphenidate, which is the structural analogue of an amphetamine. The proposed method is simple, sensitive, and accurate; thus, it may have practical application value for the daily supervision and law enforcement of milk powders with reported health functions.

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Determination of amanita peptide and tryptamine toxins in wild mushrooms by high performance liquid chromatography-tandem mass spectrometry LIU Leiqi, CHEN Jingze, FU Wusheng, TANG Cuiying 2023, 41 (11):  976-985.  DOI: 10.3724/SP.J.1123.2023.07013 Abstract ( 80 )   HTML ( 32 )   PDF (2467KB) ( 108 )   The discovery and identification of mushroom toxins has long been an important area in the fields of toxicology and food safety. Mushrooms are widely favored for their culinary and medicinal value; however, the presence of potentially lethal toxins in some species poses a substantial challenge in ensuring their safe consumption. Therefore, the development of a robust and sensitive analytical method is necessary for accurately identifying the risks associated with mushroom consumption. The study of mushroom toxins, which are characterized by their diversity and substantial variations in chemical structures, present a considerable challenge for achieving precise and high-throughput analysis. To address this issue, the present study employed a robust approach combining a solid-phase extraction (SPE) purification technique with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to establish an analytical method for the detection and quantification of five amatoxins and two tryptamines (psilocybin and bufotenine) present in some mushrooms. Several optimization procedures were undertaken, including optimizing the chromatographic conditions, mass spectrometric parameters, and sample extraction and purification. The procedure involved the extraction of dry mushroom powder with methanol containing 0.3% formic acid, followed by purification using a strong cation exchange cartridge (SCX). The analytes were separated on a T3 chromatographic column (100 mm×2.1 mm, 1.8 μm) using mobile phases of acetonitrile and 5 mmol/L ammonium acetate solution containing 0.1% formic acid. The multiple reaction monitoring (MRM) mode was employed for data acquisition. Amatoxins were quantified using matrix-matched standard calibration curves, whereas isotopic internal standards were used to quantify tryptamine. The results showed that all seven toxins exhibited good linearities (r2>0.99) within the optimized concentration range. The limits of detection (LODs) for bufotenine, psilocybin, and amatoxins were determined as 2.0, 5.0, and 10 μg/kg, respectively, while the limits of quantification (LOQs) were determined as 5.0, 10, and 20 μg/kg, respectively. The LOD and LOQ values further underscore the ability of the method to detect minute quantities of toxins, making it particularly well suited for screening food samples for potential contamination. Using dried shiitake mushroom powder as the matrix, the recoveries of the two tryptamines ranged from 80.6% to 117%, with relative standard deviations (RSDs) ranging from 1.73% to 5.98%, while the recoveries of amatoxins ranged from 71.8% to 115%, with RSDs varying from 2.14% to 9.92% at the three concentration levels. The consistent and satisfactory recoveries of amatoxins and tryptamines demonstrated the ability of this method to accurately quantify the target analytes even in a complex matrix. Comparison with the results of supplementary test method recognized by State Administration for Market Regulation for food (BJS 202008) demonstrated comparable results, indicating no significant differences (p>0.05) in amatoxin contents. The newly developed method is rapid, accurate, precise, meets the required standards, and is suitable for the detection of seven toxins in wild mushrooms. As part of the application of this method, a comprehensive investigation of the distribution of toxins in wild mushrooms from Fujian Province was undertaken. In this study, 59 wild mushroom samples from nine cities were collected in the Fujian province. Species identification was conducted using rDNA-internal transcribed space (rDNA-ITS) molecular barcode technology, which revealed the presence of toxins in the two samples. Notably, one specimen named Amanita fuligineoides contained α-amanitin, β-amanitin, and phalloidin in quantities of 607, 377, and 69.0 mg/kg, respectively. Additionally, another sample, identified as Tricholomataceae, had a psilocybin concentration of 12.6 mg/kg.

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Determination of 22 mycotoxins in milk by liquid chromatography-quadrupole/orbitrap mass spectrometry TONG Lanyan, XU Bozhou, NIE Xuemei, WANG Xiujuan, MA Jiahui, GUO Wei, LI Genrong, GONG Yingkun, XU Xiuli 2023, 41 (11):  986-994.  DOI: 10.3724/SP.J.1123.2023.07010 Abstract ( 96 )   HTML ( 21 )   PDF (1795KB) ( 124 )   Mycotoxins have carcinogenic, mutagenic, hepatotoxic, nephrotoxic, immunotoxic, neurotoxic, and teratogenic properties. Thus, these substances have attracted significant attention because they pose a threat to human health. As research on mycotoxins deepens, new structural analogues of mycotoxins are constantly being discovered. In this study, a method based on high performance liquid chromatography-quadrupole/orbitrap mass spectrometry was established for the simultaneous determination of 22 mycotoxins in milk. A simple, effective, and rapid pretreatment method was optimized by focusing on the solvent type, extractant volume, and extracting salt based on the characteristics of the mycotoxins and sample matrix. The analytes were extracted using 0.5% formic acid acetonitrile solution and added with sodium chloride to separate fats from water. The samples were centrifuged at 8000 r/min (4 ℃) for 5 min using a centrifuge and then concentrated using nitrogen. The dry residue was dissolved with 50% methanol aqueous solution. Twenty-two mycotoxins were separated on a ZORBAX Eclipse Plus C18 chromatographic column (100 mm×2.1 mm, 1.7 μm), and quantitative analysis was performed using the isotope internal standard method. The analytes were determined by liquid chromatography-quadrupole/orbitrap mass spectrometry in positive electrospray ionization mode. Qualitative analyses of the compounds were performed in full mass spectrometry/data-dependent tandem mass spectrometry (MS/dd-MS2) mode. Good linearities in the range of 0.5-100.0 μg/L were observed for the 22 mycotoxins, and the correlation coefficients (R2) were greater than 0.999. The limits of detection (S/N=3) and quantification (S/N=10) ranged from 0.3 to 0.5 μg/kg and from 1.0 to 1.5 μg/kg, respectively. The average recoveries of the 22 mycotoxins at three spiked levels of 1.5, 5.0, and 15 μg/kg were between 84.7% and 100.8%, with relative standard deviations (RSDs) of 1.2%-9.9%. These findings indicate that the method has high sensitivity and accuracy as well as good precision. Finally, the method was applied to the detection and analysis of mycotoxins in 25 actual commercial milk samples. The results revealed that the selected samples were not contaminated with any of the mycotoxins analyzed. Thus, the proposed method is useful as a quick preprocessing and confirmatory method for the simultaneous determination of mycotoxins in milk.

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Functional peptidomics analysis of Saccharomyces pastorianus protein hydrolysates based on different enzyme treatments YAN Yutong, GAO Chunyu, ZHANG Xiaomei, AN Zizhe, MA Yunzhen, HAN Linlin, ZHANG Hongwei, ZHAO Xue 2023, 41 (11):  995-1001.  DOI: 10.3724/SP.J.1123.2023.08029 Abstract ( 75 )   HTML ( 5 )   PDF (1229KB) ( 59 )   Supporting Information The aim of this study is to explore differences in the peptidomics of Saccharomyces pastorianus protein hydrolysates treated with different enzymes. Briefly, differences in the peptide fingerprints and active peptides of neutral protease/papain-hydrolyzed S. pastorianus were analyzed using ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) combined with PEAKS Online 1.7 analysis software, Peptide Ranker, and the BIOPEP database. Compared to traditional databases, the PEAKS Online uses de novo sequencing for analysis to obtain oligopeptides smaller than pentapeptides. It provides more comprehensive data of the peptide sample. In this study, enzymatic hydrolysates of S. pastorianus protein were prepared under the optimum conditions of neutral protease and papain respectively. In total, 7221 and 7062 polypeptides were identified in the hydrolysates of neutral protease and papain, respectively; among these polypeptides, 980 were common to the two enzymes. The 6241 and 6082 unique peptides found in the hydrolysates of neutral protease and papain, respectively, indicated that the peptide fingerprints of the two hydrolysates are quite different. Peptide Ranker predicted that 3013 (41.73%) and 3095 (43.83%) peptides were potentially bioactive in the hydrolysates of neutral protease and papain, respectively. According to the BIOPEP database, neutral protease and papain contained 295 and 357 active peptides, respectively; these peptides were mainly composed of angiotensin converting enzyme (ACE) inhibitors and dipeptidyl peptidase IV inhibitors and antioxidant peptides. The number of active peptides in the hydrolysate of papain was higher than that in the hydrolysate of neutral protease, but the total ion intensity of active peptides in the former was lower than that in the latter. This study revealed the influence of protease type on the composition of enzymatic hydrolysates from S. pastorianus protein. The above results provide a reference for the development of functional products of S. pastorianus protein peptides and the high-value utilization of yeast resources.

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Determination of seven mycotoxins in cereals by ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry based on the self-built database ZHANG Luxing, ZHOU Zheng, CAO Lin, QIAN Jiang 2023, 41 (11):  1002-1009.  DOI: 10.3724/SP.J.1123.2023.07014 Abstract ( 79 )   HTML ( 24 )   PDF (1316KB) ( 96 )   A method for the determination of seven mycotoxins in rice and wheat by ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF/MS) based on self-built database was established. Samples were extracted with 0.2% formic acid aqueous solution-acetonitrile (50∶50, v/v), dehydrated and salted according to the QuEChERS method (4 g of magnesium sulfate, 1 g of sodium chloride, 1 g of sodium citrate, 0.5 g of citrate disodium salt), and separated on an HSS T3 column (100 mm×2.1 mm, 1.8 μm). UPLC-Q-TOF/MS with MSE screening was performed, and the positive and negative ions of the screened mycotoxins were calibrated and quantified using matrix-matched standard curves with time of flight multiple reaction monitoring (TOF-MRM). The results showed that aflatoxin G1 (AFG1), aflatoxin G2 (AFG2), aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), and ochratoxin A (OTA) exhibited moderate matrix effects in rice, while OTA and zearalenone (ZEN) exhibited moderate matrix effects in wheat. The seven mycotoxins showed good linearities in their respective concentration ranges, with correlation coefficients (r) of 0.9900-0.9998. The limits of detection (LODs) for rice and wheat were 0.50-400 and 0.50-200 μg/kg, respectively, and the limits of quantification (LOQs) for both cereals were 1.00-800 μg/kg. In rice, the average recoveries at three spiked levels of low, medium, and high were 88.1%-123.9%, with relative standard deviations (RSDs) of 0.2%-13.6%. In wheat, the average recoveries at three spiked levels of low, medium, and high were 102.0%-123.4%, with RSDs of 0.8%-14.8%. As a result, one batch of 46 batches of rice was screened out for AFB1 and AFB2, with a screening rate of 2.2%, of which the measured values were 10.8 μg/kg and 1.2 μg/kg, respectively. According to GB 2761-2017, the maximum allowable level of AFB1 in rice is 10 μg/kg; thus, the exceeding rate for AFB1 is 2.2%. Deoxynivalenol (DON) was screened out in 9 out of 24 batches of wheat (screening rate, 37.5%), while ZEN was screened out in 19 batches (screening rate, 79.2%). According to GB 2761-2017, the maximum allowable levels of DON and ZEN in wheat are 1000 and 60 μg/kg, respectively. The levels of DON and ZEN detected in the wheat samples did not exceed these limits. The proposed method uses MSE for qualitative screening to avoid the occurrence of false positives caused by interfering compounds with mass numbers and retention times similar to those of the analytes. TOF-MRM mode is then used to quantify the positively screened mycotoxins. The method is fast, accurate, sensitive, and suitable for the isolation and quantitative detection of mycotoxin residues in rice and wheat samples. The findings provide powerful technical support for mycotoxin contamination monitoring in rice and wheat and early risk-warning efforts.

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High-throughput screening of 54 alternative plasticizers in sesame oil using gas chromatography-quadrupole time-of-flight mass spectrometry CHEN Keyun, JU Xiang, WANG Yanli, XU Xiuli, LIANG Xiuqing, LI Haixia, LI Xia, LI Fangfang, TIAN Qiyan, CHEN Qianqian, LIU Yanming, ZHANG Feng 2023, 41 (11):  1010-1020.  DOI: 10.3724/SP.J.1123.2023.08007 Abstract ( 62 )   HTML ( 24 )   PDF (1937KB) ( 97 )   Restrictions on the use of phthalates have led to the wide use of alternative plasticizers (APs) such as organophosphate, adipate, citrate, and sebacate. However, because plasticizers combine with polymers in plastic products via unstable noncovalent bonds, they can easily migrate out of these products, causing environmental pollution. In particular, their migration out of food packaging, containers, and other food-contact materials and into food has raised great concerns. Toxicological studies have shown that APs contain potentially toxic substances that can affect endocrine functions and cause neurotoxicity, genotoxicity, and other adverse effects. Thus, their potential risks to food should not be underestimated. Sesame oil is a necessity in daily cooking. The results of risk monitoring in recent years have indicated that sesame oil often contains phthalates in excess of the standard limits. However, the potential risks of APs in sesame oil have not yet been reported. Some common detection methods for APs include gas chromatography-mass spectrometry, gas chromatography-triple quadrupole mass spectrometry, and liquid chromatography-triple quadrupole mass spectrometry. Unfortunately, these methods use low-resolution mass spectrometry and are limited by the resolution, scan rate, and analysis mode. Gas chromatography-quadrupole time-of-flight mass spectrometry (GC-Q-TOF/MS) has the advantages of high resolution, sensitivity, and analysis speed. In full-scan mode, GC-Q-TOF/MS can accurately collect the full-spectrum mass number of target compounds with low content levels in complex substrates, thereby realizing efficient screening and quantitative analysis. It shows outstanding advantages in the trace analysis of pesticide residues and pollutants. Furthermore, it features strong qualitative and high screening abilities. Establishment of a personal compound database and library (PCDL) addresses limitations in the number of compounds that can be measured and enables the rapid identification of targets without the use of standard products. In addition, increasing the number of targets for synchronous screening enables the retrospective analysis of new targets. In this study, a method based on GC-Q-TOF/MS was developed for the determination of 54 APs in sesame oil. The samples were extracted with acetonitrile and purified using a PSA/silica solid-phase extraction column. The mass-spectral information of the samples was then collected by GC-Q-TOF/MS in full-scan mode, and the 54 APs were searched using an established high-resolution mass-spectrum database to simultaneously achieve the broad-spectrum screening, qualitative identification, and quantitative analysis of multiple targets. The effects of different extraction solvents and purification methods on sample extraction and purification were compared. The accuracy of the screening results was improved by optimizing the GC-separation conditions, quality-extraction window, retention-time deviation, and other screening parameters. The screening detection limits (SDLs) of the 54 APs ranged from 0.01 to 0.02 mg/kg; specifically, the SDL of 41 compounds was 0.01 mg/kg and that of 13 compounds were 0.02 mg/kg. The limits of quantification were in the range of 0.02-0.04 mg/kg. A total of 80 sesame-oil samples were rapidly screened using this method under optimal conditions. Five APs were identified from the 80 sesame-oil samples and quantitatively analyzed using the matrix-matched external-standard method. The results of this quantitative methodology showed that the five APs had good linear relationships in the range of 0.01-0.2 mg/L, with all correlation coefficients greater than 0.99. The accuracy and precision of the method were verified using a standard recovery test with blank sesame-oil samples. Under the three standard levels of 0.04, 0.08, and 0.2 mg/kg, the recoveries of the five APs ranged from 71.3% to 97.8%, and the relative standard deviations (RSDs) ranged from 0.4% to 6.1%(n=6). The developed method is fast, accurate, sensitive, and has high throughput. Thus, it can realize the efficient screening, qualitative identification, and quantitative analysis of the 54 APs in sesame oil and provides a potential solution for the monitoring of other contaminants in food.

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Screening of organophosphorus flame retardant residues in rice by QuEChERS-gas chromatography-quadrupole time-of-flight mass spectrometry LI Kangcong, YANG Jishuang, LI Xiuqin, GAO Yan, ZHANG Qinghe 2023, 41 (11):  1021-1029.  DOI: 10.3724/SP.J.1123.2023.08022 Abstract ( 70 )   HTML ( 15 )   PDF (1022KB) ( 104 )   Organophosphorus flame retardants (OPFRs) have emerged as good alternatives to brominated flame retardants, the use of which is globally restricted. In this study, a screening method based on QuEChERS-gas chromatography-quadrupole time-of-flight mass spectrometry (GC-Q-TOF/MS) was established for the determination of 21 OPFRs in rice. First, full scan (scanning range, m/z 50-450) was performed with a mixed standard solution of the 21 OPFRs (0.1 μg/g) by GC-Q-TOF/MS. The fragmentation pathways of these OPFRs were then investigated to explore their cleavage fragments, the interrelationships among fragments, and the possible cleavage modes of alkylated, chlorinated, and aromatic OPFRs. The retention times, isotopic abundance ratios, and molecular formulas of the characteristic fragments as well as the exact mass of the compounds were obtained to establish a mass spectral library of the OPFRs. Rice samples were extracted and purified by the QuEChERS method, and 0.5% formate acetonitrile solution was used as the extraction solvent; 4 g of magnesium sulfate, 1 g of sodium chloride, 0.5 g of disodium hydrogen citrate, and 1 g of sodium citrate as the extraction-salt combination; and 50 mg of primary secondary amine (PSA), 50 mg of octadecylsilane (C18), and 150 mg of magnesium sulfate as the purification materials. The chromatographic separation of the 21 OPFRs was completed within 16 min under optimized temperature program conditions on the DB-5MS UI column. The screening parameters were optimized, and a full scan of the samples was performed under the following conditions: number of characteristic fragment ions ≥2; accurate mass window=±2×10-5 (±20 ppm); retention time deviation=±0.2 min, and ion abundance deviation<20%. The developed method was applied to the screening 21 OPFRs in the samples. The results indicated that the matrix interference was greatly reduced by decreasing the extraction accurate mass window, thereby improving the signal-to-noise ratio of the analytes. The targets were extracted from the matrix interference and background noise using deconvolution software, which improved the match between the target compounds and the mass spectral library. The detection rates of alkyl and aromatic OPFRs increased by 22% and 25%, respectively, when the spiking level was increased from 2 to 10 ng/g. Among the chlorinated OPFRs, only tris(2-chloroisopropyl) phosphate (TCIPP) was not detected at a spiking level of 2 ng/g, indicating that chlorinated OPFRs could be identified even at low concentrations. The characteristic ions of the detected compounds matched those of the home-made mass spectral library well, indicating that the practical application of the home-made mass spectral library. The established screening method was applied in the determination of OPFRs in rice samples from different regions in China. A total of 11 OPFRs were detected, among which trimethyl phosphate (TMP), tri-iso-butyl phosphate (TiBP), and tris(3,5-dimethylphenyl) phosphate (T35DMPP) had the highest detection rates. These results indicate that these three OPFRs are widely used and can easily come into contact with rice samples through various routes. Differences in the types of OPFRs detected in the actual samples may be related to the types of OPFRs produced in local factories. OPFRs can be detected in rice samples by the developed GC-Q-TOF/MS screening method, which is helpful for the identification of OPFRs in complex matrix samples.

Technical Notes

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Rapid determination of 13 β-blockers in health foods by ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry LI Tonghui, FENG Feng, SHEN Yiming, ZHANG Feng 2023, 41 (11):  1030-1037.  DOI: 10.3724/SP.J.1123.2023.06006 Abstract ( 67 )   HTML ( 18 )   PDF (1116KB) ( 75 )   A method based on ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry was developed for the rapid determination of 13 β-blockers in health foods. The MS fragmentation pathways of the analytes were subsequently investigated. The optimal MS conditions, extraction solvents, mobile phases, and matrix effects were evaluated in detail. The samples were extracted with methanol, filtered by high-speed centrifugation and ultrasonic treatment, and then separated on an Acquity UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm) with gradient elution using acetonitrile and 0.1% (v/v) formic acid aqueous solution as mobile phases. MS analysis was conducted in positive-ion mode, and the data were collected using full mass and data-dependent MS2 scans (Full MS/dd-MS2). The efficient separation and high-precision primary and secondary scanning of the 13 β-blockers in health foods were realized within 10 min, and accurate mass numbers and fragment-ion information were obtained. The methodological validation showed good linear relationships in the range of 0.5-100 μg/L, with correlation coefficients (r)≥0.9912. The limits of detection ranged from 1 to 10 μg/kg. When the standard substances were added to the blank sample in the amount of 10-200 μg/kg, the recoveries were in the range of 75.3%-108.4%, and the relative standard deviations ranged from 0.9% to 10.0% (n=6). The method was used to screen 30 batches of commercially available health foods, and none of the 13 β-blockers was detected. The proposed method is fast, accurate, and sensitive, and can be used for the rapid determination of β-blockers in health foods.

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Determination of furosine in liquid milk by high performance liquid chromatography-quadrupole time-of-flight mass spectrometry YAO Guihong, LING Yun, ZHANG Yujia, XING Shige, YAO Meiyi, GUO Wei, ZHANG Feng 2023, 41 (11):  1038-1043.  DOI: 10.3724/SP.J.1123.2023.05009 Abstract ( 92 )   HTML ( 15 )   PDF (815KB) ( 148 )   Furosine is often used both domestically and internationally as an indicator of the degree of heating to evaluate milk quality. However, in actual detection, the complexity of the milk matrix may lead to the inaccurate quantification of furosine in liquid milk. Therefore, in this study, an efficient and accurate method based on high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF/MS) was established to determine furosine in liquid milk. A 2.00 mL milk sample was hydrolyzed with 5 mL 12.00 mol/L hydrochloric acid solution and 1 mL water at 110 ℃ for 12 h. After hydrolysis, vortex-mixing and filtration were performed. The filtrate was diluted six times with 6.00 g/L ammonium acetate solution and then analyzed. Gradient elution was performed with 0.20% formic acid aqueous solution and acetonitrile solution as mobile phases, followed by chromatographic separation on an AQ-C18 column (150 mm×3.5 mm, 5 μm). The data were collected by Q-TOF/MS with an electrospray ionization source operated in positive-ion mode. The accuracy of the quantification of furosine in milk was assessed by investigating the effects of the hydrochloric acid concentration (0.30, 1.25, and 3.00 mol/L) in the furosine solution on the MS response. The results showed that high hydrochloric acid concentrations inhibited the response signals. A good linear relationship was obtained in the mass concentration range of 0.05-2.00 mg/L, with a correlation coefficient (r) of 0.994. The limit of detection of the method was 0.50 mg/100 g, which meets the requirements of actual sample detection. The average recoveries of furosine ranged from 79.9% to 119.7% at three spiked levels of 1.52, 3.03, and 15.17 mg/100 g, with relative standard deviations of 1.4%-2.6%. The method was applied to detect 303 samples from 101 batches of pasteurized milk sold in the market, and the contents of furosine in these samples ranged from 5.1 to 11.9 mg/100 g. The proposed method is characterized with high efficiency, recovery, sensitivity, and accuracy. Thus, it can be used for the determination of large quantities of samples and provides technical support for the continuous promotion of the high-quality development of the whole dairy industry chain.