Quantitative determination of ceftiofur-related residues in bovine raw milk by LC-MS/MS with electrospray ionization

A sensitive and specific liquid chromatography/tandem mass spectrometry (LC-MS/MS) method for the quantitative determination of ceftiofur-related metabolites that retain the ß-lactam structure, expressed as desfuroylceftiofur free acid has been developed and validated for raw bovine milk. The method described is based on the cleavage of the disulfide and/or thioester bonds between the metabolites and their sulfur-containing moiety, using dithioerythritol to yield desfuroylceftiofur and further stabilization to desfuroylceftiofur-acetamide (DCA) using iodacetamide. The final extract containing the DCA derivative was cleaned up by a simple solid-phase extraction step prior to separation on a phenylether reversed phase HPLC-column. Chromatography was performed using a formic acid/methanol gradient. Collision induced dissociation with argon was used for fragmentation of the pseudomolecular ion [M+H]⁺ to achieve the required specificity of the method. The new EU guidelines for identification and quantification were fulfilled.     

Azaspiracid shellfish poisoning: unusual toxin dynamics in shellfish and the increased risk of acute human intoxications

A number of recent acute human intoxications in Europe from the consumption of Irish mussels have been attributed to the presence of a new class of toxins named azaspiracids. The study demonstrates that azaspiracids behave differently from other polyether toxins, and this accounts for most false-negative results in the mouse bioassay employed by regulatory agencies to detect azaspiracids. Typically, polyether toxins are concentrated in the digestive glands of shellfish, but this is not always the situation with azaspiracids. Liquid chromatography-mass spectrometry (LC-MS), especially multiple tandem MS methods, have been applied to demonstrate that azaspiracid (AZA1) and its methyl- and demethyl- analogues, AZA2 and AZA3 respectively, are distributed throughout shellfish tissues. Using conventional mouse bioassay protocols, only 0-40% of the total azaspiracid content of shellfish was used in the assay, which could directly account for false-negative results. It was also observed that the toxin profiles differed significantly in various mussel tissues with AZA1 as the predominant toxin in the digestive glands and AZA3 predominant in the remaining tissues.     

QuEChERS结合高效液相色谱-串联质谱法测定粮谷中16种真菌毒素

建立了QuEChERS结合高效液相色谱-串联质谱仪(HPLC-MS/MS)同时测定粮谷中16种真菌毒素残留量的方法,样品经乙腈-水-乙酸(84∶15∶1,v/v)溶液超声提取,提取液采用C18、MgSO4净化,净化液过0.22μm微孔滤膜,用HPLC-MS/MS分析检测。Acquity UPLC BEH C18柱为分析柱,甲醇/乙腈(4+6)-0.1%甲酸水溶液为流动相进行梯度洗脱,采用电喷雾正负离子(ESI+、ESI-)模式同时电离,多反应监测(MRM)模式检测,外标法定量。结果表明,16种真菌在相应的浓度范围内线性关系良好(相关系数r2>0.995),方法定量限为0.3~3.5μg/kg,在低、中、高3个不同浓度的添加水平下,平均回收率为90.6%~106.5%,相对标准偏差≤8.8%(n=6),满足日常检测要求。该方法前处理简单,测定快速、准确,灵敏度高,适用于粮谷中16种真菌毒素残留的定性和定量分析。     

液相色谱-串联质谱法同时测定玉米粉中6种真菌毒素

建立了同时测定玉米粉中6种真菌毒素的液相色谱-串联质谱法.采用乙腈-0.3%乙酸水溶液超声提取样品中的待测物,吹干有机溶剂后,提取液经HLB固相萃取小柱净化,浓缩吹干后用流动相定容,LC-MS/MS检测.该方法检出限低,在0.03～4.0μg/kg添加水平内,回收率在66.7%～90.2%之间,变异系数在7.1%～11.7%.结果表明,该法灵敏,准确,适用于玉米粉中6种真菌毒素含量的同时测定.     

Screening assay of angiotensin-converting enzyme inhibitory activity from complex natural colourants and foods using high-throughput LC-MS/MS

Inhibition of angiotensin-converting enzyme (ACE) by various foods decreases the blood pressure. ACE inhibitors derived from natural components may be of therapeutic value in preventive medicine. In this study, we report a novel screening assay of ACE inhibitors from complex natural colourants and foods that employ solid phase extraction (SPE), high-throughput liquid chromatography (LC) separation, and stable isotope dilution electrospray tandem mass spectrometry (SID-ESI-MS/MS). When a target sample was subjected to N-Hippuryl-His-Leu (HHL) and ACE in phosphate buffer (pH 7.4), generated hippuric acid (HA) was extracted by SPE. LC/SID-ESI-MS/MS detection of HA allowed us to accurately identify the effects of complex substances such natural colourants and foods that inhibit the ACE of HHL. The major HA and HA-d₅ fragment ions at m/z 180 → 105 and 185 → 110 in the multiple reaction monitoring (MRM) mode can quantify levels that are lower than other methods. The LC/SID-ESI-MS/MS method described here is a rapid, selective, sensitive, and highly reproducible method for the determination of HA in various samples. Based on the assay developed, all samples such as natural colourants, infant formula, soy paste, ketchup, mayonnaise, wheat flour, orange juice, supplement drink, tea, and coffee could be accurately measured for ACE inhibition in various matrices. High-throughput LC/SID-ESI-MS/MS assay has no limitations in the evaluation of inhibition activity in various natural samples such as colour, high-matrix, and processed foods.     

Analysis of ochratoxin A in pig kidney and rye flour using liquid chromatography tandem mass spectrometry (LC/MS/MS)

A liquid chromatography electrospray tandem mass spectrometric (LC/MS/MS) method is described for analysis and confirmation of ochratoxin A in pig kidney and rye flour using derivatization of ochratoxin A to the methyl ester. Ochratoxin A methyl(d₃)ester is used as internal standard. The method works well, the detection limit is 0.02 μ g/kg and the repeatability (coefficient of variation) is between 6% and 16% in the contamination range 0.5 to 8 μ g/kg.     

Screening assay of residual antibiotics in livestock samples by LC-MS/MS

A LC-MS/MS screening assay of multi-class antibiotics was developed for 19 residual antibiotics in livestock samples. Sample preparation employed the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach using 0.5% formic acid in acetonitrile-methanol (8 : 2), with salting-out using magnesium sulfate, trisodium citrate and sodium chloride. Recovery values from 5 different livestock samples ranged from 45.5 to 121.6%, and the RSDs were under 18% at two concentration levels. The limit of quantification values of 19 analytes were under 10 μg/kg in all livestock samples, and the procedure can detect almost all analytes under the MRL. Screening capability was confirmed by employing spiked samples. This new screening assay for residual antibiotics in livestock samples is expected to be useful for routine laboratory tests.     

Analysis of glyphosate residues in cereals using liquid chromatography-mass spectrometry (LC-MS/MS)

A fast and specific method for the determination of glyphosate in cereals is described. The method is based on extraction with water by ultrasonication. The samples are cleaned up and separated by high-performance liquid chromatography on a polystyrene-based reverse-phase column (clean-up) in series with an ion chromatography column (separation) using NaHCO₃ as eluent. A micro-membrane suppressor was inserted after the separator column to remove the Na⁺ ions before detection by electrospray ionization mass spectrometry in the negative-ion mode. In MS/MS, mode the following transitions were monitored m/z 168 →150 (glyphosate) and 170 →152 (internal standard 2-¹³ C¹⁵N-glyphosate) for quantification. The mean recovery was 85% (n=32) at spiking levels from 0.03 to 0.33 mg kg^-1. From 1998 to 2001, from the analysis of about 50 samples per annum, a reduction in the glyphosate residues was observed owing to a Danish trade decision not to use grain with glyphosate residues for milling or bread production.     

烟气中烟草特有亚硝胺LC-MS/MS分析方法的改进

为更加快速准确地测定不同类型卷烟烟气中TSNAs含量,进行了液相色谱串联质谱(LC-MS/MS)法测定条件改进试验。结果表明:①10 mmol/L乙酸铵水溶液可以替代100 mmol/L乙酸铵水溶液作萃取剂;②萃取液经0.45μm水相滤膜过滤后可直接进行LC-MS/MS仪分析;③同时用NNN-d4,NNK-d4,NAT-d4,NAB-d4作内标定量结果更为准确;④TSNAs的检出限为0.06~0.14 ng/mL,回收率91%~100.6%,RSD 0.76%~5.42%。该方法适用于混合型、烤烟型卷烟样品主流烟气中TSNAs的定量分析。     

Structural characterization of metabolites after the microbial degradation of type A trichothecenes by the bacterial strain BBSH 797

Contamination of feed with trichothecenes, a group of Fusarium mycotoxins, leads to losses in performance due to their immunosupressive effects and the negative effect on the gastrointestinal system in animal production. A possible way of detoxification is microbial degradation, which was the focus of this study. A bacterial strain - BBSH 797 - which can degrade some mycotoxins of the trichothecene group, has already been isolated. It transforms deoxynivalenol (DON) into its metabolite DOM-1, the non-toxic deepoxide of DON. Analogous to the microbial degradation of DON, the transformation of six different type A trichothecenes was observed. The metabolites appearing were characterized by GC-MS after derivatization with TRI-SIL®TBT. Two metabolites were additionally identified by liquid chromatography-mass spectrometry with particle beam interface (LC-PB-MS) with electron impact (EI)-ionization mode. The major finding was that scirpentriol was completely transformed into its non-toxic metabolite deepoxy scirpentriol, while the mycotoxin T-2 triol underwent a more complicated metabolism. According to the study, T-2-triol was degraded into its non-toxic deepoxy form and into T-2 tetraol, which was then further metabolized to deepoxy T-2 tetraol. GC-MS after derivatization with TRI-SIL®TBT was suitable for the structural characterization of trichothecenes and their degradation products. Besides the mass spectra of already known degradation products, spectra of new metabolites could be recorded by LC-PB-MS.     

液相色谱-串联质谱法测定葡萄酒中赭曲霉毒素A

以赭曲霉毒素B为内标物,建立了应用固相萃取-液相色谱-串联质谱法(SPE-LC-MS/MS)对葡萄酒中赭曲霉毒素A残留量测定的方法。葡萄酒样品经过调节pH值至7.0和C18固相萃取净化的前处理过程后,采用液相色谱-串联质谱法进行测定(正离子方式,多反应监测模式)。方法定量限(LOQ)为2.0g/L。内标法定量计算,在0~10g/L质量浓度范围内线性相关系数0.998。在葡萄酒中分别进行2.0g/L、4.0g/L和8.0g/L三个添加水平的测试,该检测方法回收率范围97.6%~109.7%,相对标准偏差(RSD)3.0%~4.6%。方法简便、快速、准确,可用于葡萄酒中赭曲霉毒素A的定量测定。     

LC-MS/MS法测定11种鲜切油炸马铃薯片中丙烯酰胺的含量

目的:在相同的设定条件下,进行11种鲜切油炸马铃薯片中丙烯酰胺含量的测试.方法:将马铃薯热烫60s,表面干燥,180℃油炸100s,脱油,前处理,采用液相-质谱联用检测不同品种的马铃薯油炸薯片中丙烯酰胺含量.结果:在相同的油炸试验条件下,丙烯酰胺含量较低的是D-519、陇薯-3号、中薯-7号、LK99等,丙烯酰胺含量较高的是中薯-8号、夏波蒂、中薯-3号等.结论:马铃薯品种对鲜切油炸薯片中丙烯酰胺含量有较大的影响.     

Development and Application of LC-MS/MS Method for the Detection of Naturally Occurring Thiouracil in Milk Samples

The liquid chromatography tandem mass spectrometry method to determine five thyreostats in cow’s milk has been developed and validated according to 2002/657/EC criteria. Thyreostats were extracted with methanol from the milk after the precipitation of the protein. Then, the derivatisation of analytes with 3-iodobenzylbromide was performed and derivatives were analysed on a Poroshell C18 column with triple quadrupole MS detection. For all compounds, good recoveries were obtained; the decision limit CCα and the detection capability CCβ of five thyreostats do not exceed 2.2 and 3.8 μg L^?1, respectively. Thirty-four samples of milk were tested for the presence of thyreostats; in 13, thiouracil was found above the decision limit. The highest concentration in raw milk reached a value of 4.2 μg L^?1. To the authors’ knowledge, this study is the first to report the presence of naturally occurring thiouracil in cow’s milk.     

液相色谱-串联质谱法测定豆类中左旋多巴

文章建立一种豆类中左旋多巴的液相色谱-串联质谱测定方法。样品经0.3 mol/L乙酸水溶液超声提取,Agilent Proshell 120 SB-C18(2.1 mm×150 mm,2.7μm)色谱柱分离,以0.1%甲酸水-甲醇为流动相进行梯度洗脱,多反应监测(MRM),内标法定量。结果表明,左旋多巴在0.1~5.0 mg/L范围内线性关系良好,相关系数为0.9994,检出限为1.5 mg/kg,定量限为5.2 mg/kg,方法的平均加标回收率为96.9%~105.5%,日内精密度和日间精密度均小于4%,具有操作简单、灵敏度高、准确度高、重现性好等特点,能够很好满足豆类中左旋多巴含量的检测需要。     

液相色谱—串联质谱法检测纺织品中芦荟成分

建立高效液相色谱—串联质谱法测定纺织品中芦荟苷、芦荟大黄素和大黄酚含量的方法。样品经甲醇60℃超声波浴提取30 min后,在Agilent Eclipse XDB-C18(2.1 mm×150 mm,3.5 m)色谱柱上分离,以10 mmol/L乙酸铵溶液(pH=5.75)和乙腈为流动相进行梯度洗脱。三重四级杆质谱采用电喷雾离子源负离子模式在多反应监测(MRM)模式下检测被分析物,外标法定量。纺织样品在3个加标水平时,平均回收率为85.5%～99.9%,相对标准偏差(RSDs)为1.76%～5.92%。该方法具有快速、灵敏、准确、可重复的特点,可应用于纺织品中芦荟成分的痕量分析。     

Method validation and analysis of nine dithiocarbamates in fruits and vegetables by LC-MS/MS

An analytical method for separation and quantitative determination of nine dithiocarbamates (DTCs) in fruits and vegetables by using LC-MS/MS was developed, validated and applied to samples purchased in local supermarkets. The nine DTCs were ziram, ferbam, thiram, maneb, zineb, nabam, metiram, mancozeb and propineb. Validation parameters of mean recovery for two matrices at two concentration levels, relative repeatability (RSD_r), relative within-laboratory reproducibility (RSD_R) and LOD were obtained for the nine DTCs. The results from the analysis of fruits and vegetables served as the basis for an exposure assessment within the given commodities and a risk assessment by comparing the calculated exposure to the acceptable daily intake and acute reference dose for various exposure groups. The analysis indicated positive findings of DTCs in apples, pears, plums, table grapes, papaya and broccoli at concentrations ranging from 0.03 mg/kg to 2.69 mg/kg expressed as the equivalent amount of CS₂. None of the values exceeded the Maximum residue level (MRL) set by the European Union, and furthermore, it was not possible to state whether illegal use had taken place or not, because a clear differentiation between the various DTCs in the LC-MS/MS analysis was lacking. The exposure and risk assessment showed that only for maneb in the case of apples and apple juice, the acute reference dose was exceeded for infants in the United Kingdom and for children in Germany, respectively.     

液质联用测定氟尼辛葡甲胺的条件优化

建立了液相色谱-四级杆串联质谱法测定氟尼辛葡甲胺含量的方法,对其检验条件进行了优化。采用Agilent eclipse plus C18色谱柱分离,用体积浓度0.1%甲酸溶液、0.1%甲酸乙腈溶液作为流动相梯度洗脱,电喷雾正离子(ESI+)模式电离,多反应监测(MRM)模式检测,外标法定量。该方法操作灵敏度高,重复性好。     

Determination of aflatoxins in food using LC/MS/MS

 A liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometric method is described for the determination of aflatoxins B₁, B₂, G₁ and G₂ in food with the use of aflatoxin M₁ as an internal standard. The method works well with matrices such as those of figs and peanuts, but there are problems with spices, due to limitations of the clean-up method used. Received: 15 October 1997     

An improved LC-MS/MS method for the quantitation of acrylamide in processed foods

An improved liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of acrylamide in processed foods. The homogenized samples, spiked with ¹³C₃-acrylamide as an internal standard, were extracted with water and centrifuged. D₅-3-chloropropanediol as a recovery standard was added to 1-ml aliquots, and the sample was purified with a C₁₈-cartridge column. The extract was directly analyzed using LC-MS/MS without derivatization. The ion transitions of 72–55 m/z (acrylamide), 75–58 m/z (¹³C₃-acrylamide), and 116–98 m/z (d₅-3-chloropropanediol) were found to be the most reliable for the identification and quantification of acrylamide in multiple reaction monitoring. The limit of quantification for acrylamide, defined as a signal-to-noise ratio of 10:1, was 2 μg/kg. The use of d₅-3-chloropropanediol minimized the effects of variation in the sample matrixes and increased the quality of analysis. This method could be applied to the quantification of acrylamide in processed foods.