Determination of deoxynivalenol in processed foods

Deoxynivalenol (DON), commonly referred to as vomitoxin, belongs to a class of naturally occurring mycotoxins produced by Fusarium fungi. The presence of DON in foods is a human health concern. The frequency of occurrence of DON in wheat is high, although cleaning prior to milling can reduce DON concentration in final products, and food processing can partially degrade the toxin. This paper describes a method for the determination of DON in some major wheat food products, including bread, breakfast cereals, pasta, pretzels, and crackers. Test samples containing 5% polyethylene glycol were extracted with water. After blending and centrifuging, the supernatant was diluted with water and filtered through glass microfiber filter paper. The filtrate was then passed through an immunoaffinity column and the toxins eluted with methanol. The toxins were then subjected to RPLC separation and UV detection. The accuracy and repeatability characteristics of the method were determined. Recoveries of DON spiked at levels from 0.5 to 1.5 microg/g in the five processed foods were >70%. SD and RSD values ranged from 2.0 to 23.5% and from 2.0 to 23.2%, respectively. HorRat values were <2 for all of the matrixes examined. The method was found to be acceptable for the matrixes examined. LC/MS/MS with multiple-reaction monitoring was used to confirm the identity of DON in naturally contaminated test samples.     

LC/MS method using cloud point extraction for the determination of permitted and illegal food colors in liquid, semiliquid, and solid food matrixes: single-laboratory validation

A cloud point extraction method is reported using LC/MS for the determination of regulated water-soluble food colors (Allura Red, Sunset Yellow, erythrosine, and tartrazine) and banned fat-soluble synthetic azo dyes (Sudan I, II, III, and IV; Red B; 7B; Black B; Red G; Metanil Yellow; and Rhodamine B). The extraction of all 14 colors was carried out with cloud point extraction using the nonionic surfactant Triton X 114. Optimized conditions for cloud point extraction were 3% Triton X 114 (w/v), 0.1 M ammonium acetate, and heating at 50 degrees C for 30 min. This approach proved effective in giving quantitative recoveries from a diverse range of food matrixes, and optimized LC gave baseline chromatographic separation for all colors including Sudan IV and Red B. Single-laboratory validation was performed with spiking into liquid matrixes (wine and homemade wine), semiliquid matrixes (sauce and homemade paprika paste), and solid matrixes (spice and homemade chili powder) using the respective blank matrixes for matrix-matched calibration. The LOQ values for water-soluble colors were in the range of 15-150 mg/kg, and for the fat-soluble colors, 0.1-1.5 mg/kg. The mean recovery values were in the range of 69.6-116.0% (except Allura Red and Sunset Yellow in wine, for which recoveries were lower). The mean RSDs for colors were in the range of 4.0-14.8%. A small survey was conducted of samples of confectionery products, dried fruits, wines, bitter sodas, juices, sauces, pastes, and spices, which demonstrated the applicability of the method to a diverse selection of real food samples. Allura Red was detected in strawberry jelly and Sunset Yellow in artificial saffron.     

高效液相色谱–串联质谱内标法测定动物源性食品中玉米赤霉烯酮及其代谢产物

建立高效液相色谱–串联质谱法(HPLC–MS/MS)测定动物源性食品中玉米赤霉烯酮及其5种代谢产物(α-玉米赤霉烯醇、β-玉米赤霉烯醇、α-玉米赤霉醇、β-玉米赤霉醇、玉米赤霉酮)残留量。在样品中加入4种同位素内标(13C18–玉米赤霉烯酮,D7–α-玉米赤霉烯醇,D7–β-玉米赤霉烯醇,D5–α-玉米赤霉醇)后,经β-葡萄糖苷酶/硫酸酯酶酶解,用叔丁基甲基醚萃取,取上清液氮吹至近干后用三氯甲烷复溶,再用氢氧化钠溶液反向萃取,以HLB固相萃取柱净化后,用HPLC–MS/MS检测。结果表明,玉米赤霉烯酮及其代谢产物在1.0~100.0μg/L范围内线性关系良好,相关系数均大于0.996,方法的检出限为0.04~0.13μg/kg,定量限为0.11~0.43μg/kg。在1.0、4.0、10.0μg/kg三种加标浓度水平下,回收率为77.7%~105.5%,测定结果的相对标准偏差为4.8%~9.8%(n=6)。该方法准确、可靠,灵敏度高,适用于动物源性食品中玉米赤霉烯酮及其代谢产物的定量分析。     

Application of ultra-performance liquid chromatography/tandem mass spectrometry for the measurement of vitamin D in foods and nutritional supplements

Ultra-performance liquid chromatography (UPLC)/MS/MS was applied to measure vitamin D in various foods and nutritional supplements. The run-time of the chromatographic separation was cut from 20 min in HPLC/MS/MS to 10 min in UPLC/MS/MS, while equal or better separation efficiency was achieved to deal with complex food matrixes. Under the optimized conditions, all the previtamins of vitamin D3, D2, and isotope-labeled vitamin D3 were baseline-separated from their corresponding vitamins. It was also demonstrated that many sterol isomers in complex food matrixes that interfere in the analysis could be well-separated from the analytes. Accuracy of this method was evaluated by analysis of NIST SRM 1849 infant formula reference material. With eight replicates, the average vitamin D3 concentration was 0.251 +/- 0.012 mg/kg, an excellent agreement with the certified value of 0.251 +/- 0.027 mg/kg. In addition, spike recovery from a commercial infant formula matrix was in the range of 100 to 108% for both vitamins D3 and D2 at three spike concentration levels. The spike recovery for an even more complex matrix, pet food, was 101-105%. LOQ values were 0.026 and 0.033 IU/g, or 0.086 and 0.11 IU/mL in solution, for vitamins D3 and D2, respectively. The dynamic range had three orders of magnitude, which made the method flexible and useful to deal with the wide concentration range of vitamin D in various samples. The method was robust based on the results of changing the parameters of LC separation and MS measurement. This accurate and reliable vitamin D method increased instrument efficiency and analysis productivity significantly.     

GC/MS法测定大米中精噁唑禾草灵和氰氟草酯残留量

采用乙腈提取,NH2固相萃取柱净化,GC/MS测定,建立了大米中精噁唑禾草灵和氰氟草酯残留量的测定方法。添加精噁唑禾草灵质量分数为0.02,0.2,0.5mg/kg,平均回收率分别为82.3%,88.8%和90.7%,相对标准偏差分别为6.8%,8.2%和3.7%,检出限为0.02 mg/kg;添加氰氟草酯质量分数为0.02,0.2,0.5mg/kg,平均回收率分别为87.7%,94.2%和92.3%,相对标准偏差分别为8.6%,5.6%和7.3%,检出限为0.02mg/kg。     

Use of a multifunctional column for the determination of deoxynivalenol in grains, grain products, and processed foods

Deoxynivalenol (DON), also known as vomitoxin, belongs to a class of naturally occurring mycotoxins produced by Fusarium spp. DON, 12, 13-epoxy-3,7 trihydroxytrichothec-9-en-8-one, is one of the most frequently detected mycotoxins in agricultural commodities worldwide. A method consisting of extraction, filtration, column cleanup, and RP-HPLC-UV separation and quantitation was validated for the determination of DON in grains (rice and barley), grain products (whole wheat flour, white flour, wheat germ, and wheat bran), and processed foods (bread, breakfast cereals, and pretzels). A 25 g test portion was extracted with 100 mL acetonitrile-water (84 + 16, v/v). After blending for 3 min, the supernatant was applied to a multifunctional column (MycoSep 225). The purified filtrate (2 mL) was evaporated to dryness and redissolved in the mobile phase. The toxins were then subjected to RP-HPLC-UV analysis. The accuracy and repeatability characteristics of the method were determined. Recoveries of DON added at levels ranging from 0.5 to 1.5 microg/g for all test matrixes were from 75 to 98%. SD and RSD(r) ranged from 0.7 to 11.6% and 0.9 to 12.7%, respectively. Within-laboratory HorRat values were from 0.1 to 0.7 for all matrixes analyzed. The method was found to meet AOAC method performance criteria for grains, grain products, and processed foods. The identity of DON in naturally contaminated test sample extracts was confirmed by HPLC/MS/MS analysis.     

液相色谱-质谱/质谱法对多种食品基体中三聚氰胺的检测

采用超声、振荡、液液萃取、离心等方法提取14种复杂食品基体中的三聚氰胺,提取液经阳离子交换固相萃取柱净化后,采用液相色谱-质谱/质谱法测定多种食品基体中的三聚氰胺.涉及的食品基体包括豆类制品、饮料、糕点、含乳饼干、鲜蛋、蛋制品和调味品6类基体14种食品.方法的检出限为0.005 ～0.012 5 mg/kg,回收率为75% ～115%,RSD小于18%;定量下限为0.025 ～0.062 5 mg/kg,回收率为84% ～106%,RSD小于10%.中、高浓度添加回收率为82% ～110%,RSD小于12%.方法灵敏、准确、有效.     

Determination of cyclamate in foods by ultraperformance liquid chromatography/tandem mass spectrometry

A highly sensitive and selective method that requires minimal sample preparation was developed for the confirmation and quantitation of cyclamate in a variety of foods by high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). Sample preparation consisted of homogenization followed by extraction and dilution of cyclamate with water. HPLC separation was achieved using a bridged ethyl hybrid C18 high-pressure column with a mobile phase consisting of 0.15% acetic acid and methanol. Under electrospray ionization negative conditions, quantitation was achieved by monitoring the fragment m/z = 79.7 while also collecting parent ion m/z = 177.9. Two food matrixes, diet soda and jelly, were subjected to a validation procedure in order to evaluate the applicability of the method. The cyclamate limit of detection for both matrixes was determined to be 0.050 microg/g with a limit of quantitation of 0.150 microg/g. The correlation coefficient of the calibration curves was >0.9998 from 0.0005 to 0.100 microg/mL. The method has been used for the determination of cyclamate in several foods and the results are presented.     

Quantitation of acrylamide in food products by liquid chromatography/mass spectrometry

A simple and inexpensive liquid chromatography/mass spectrometry (LC/MS) method was developed for the quantitation of acrylamide in various food products. The method involved spiking the isotope-substituted internal standard (1-C13 acrylamide) onto 6.00 g of the food product, adding 40 mL distilled/deionized water, and heating at 65 degrees C for 30 min. Afterwards, 10 mL ethylene dichloride was added and the mixture was homogenized for 30 s and centrifuged at 2700 x g for 30 min, and then 8 g supernatant was extracted with 10, 5, and 5 mL portions of ethyl acetate. The extracts were combined, dried with sodium sulfate, and concentrated to 100-200 microL. Acrylamide was determined by analysis of the final extract on a single quadrupole, bench-top mass spectrometer with electrospray ionization, using a 2 mm id C18 column and monitoring m/z = 72 (acrylamide) and m/z = 73 (internal standard). For difficult food matrixes, such as coffee and cocoa, a solid-phase extraction cleanup step was incorporated to improve both chromatography and column lifetime. The method had a limit of quantitation of 10 ppb, and coefficients of determination (r2) for calibration curves were typically better than 0.998. Acceptable spike recovery results were achieved in 11 different food matrixes. Precision in potato chip analyses was 5-8% (relative standard deviation). This method provides an LC/MS alternative to the current LC/MS/MS methods and derivatization gas chromatography/mass spectrometry methods, and is applicable to difficult food products such as coffee, cocoa, and high-salt foods.     

Glycidyl fatty acid esters in food by LC-MS/MS: method development

An improved method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the analysis of glycidyl fatty acid esters in oils was developed. The method incorporates stable isotope dilution analysis (SIDA) for quantifying the five target analytes: glycidyl esters of palmitic (C16:0), stearic (C18:0), oleic (C18:1), linoleic (C18:2) and linolenic acid (C18:3). For the analysis, 10 mg sample of edible oil or fat is dissolved in acetone, spiked with deuterium labelled analogs of glycidyl esters and purified by a two-step chromatography on C18 and normal silica solid phase extraction (SPE) cartridges using methanol and 5% ethyl acetate in hexane, respectively. If the concentration of analytes is expected to be below 0.5 mg/kg, 0.5 g sample of oil is pre-concentrated first using a silica column. The dried final extract is re-dissolved in 250 μL of a mixture of methanol/isopropanol (1:1, v/v), 15 μL is injected on the analytical C18 LC column and analytes are eluted with 100% methanol. Detection of target glycidyl fatty acid esters is accomplished by LC-MS/MS using positive ion atmospheric pressure chemical ionization operating in Multiple Reaction Monitoring mode monitoring 2 ion transitions for each analyte. The method was tested on replicates of a virgin olive oil which was free of glycidyl esters. The method detection limit was calculated to be in the range of 70-150 μg/kg for each analyte using 10 mg sample and 1-3 μg/kg using 0.5 g sample of oil. Average recoveries of 5 glycidyl esters spiked at 10, 1 and 0.1 mg/kg were in the range 84% to 108%. The major advantage of our method is use of SIDA for all analytes using commercially available internal standards and detection limits that are lower by a factor of 5-10 from published methods when 0.5 g sample of oil is used. Additionally, MS/MS mass chromatograms offer greater specificity than liquid chromatography-mass spectrometry operated in selected ion monitoring mode. The method will be applied to the survey of glycidyl fatty acid esters in food products on the Canadian market.     

A fast method for screening and/or quantitation of tetrahydrocannabinol and metabolites in urine by automated SPE/LC/MS/MS

Marijuana is one of the most commonly used illicit substances. The high usage of this substance results in it being commonly encountered in clinical samples throughout the USA and Europe. Due to its wide availability and use, marijuana is also commonly encountered in forensic toxicology laboratories. The proposed method utilized an automated solid phase extraction (SPE) coupled to liquid chromatography/mass spectrometry (LC/MS). The automated SPE procedure was developed using Hysphere C8-EC sorbent, and the high performance liquid chromatography (HPLC) separation was performed using an Xterra MS C₁₈ column with a total runtime of 10 min. The standard curves linearity generally fell between 6 and 500 ng/mL. The limits of detection ranged from 2 to 4 ng/mL, and the limits of quantitation ranged from 8 to 12 ng/mL. The bias and imprecision were determined using a simple analysis of variance (single factor). The results demonstrate bias as <11% and percent imprecision as <12% for all components at four quality control levels. This method has been in use for over 2 years and has been applied to numerous forensic samples. When compared to other published methods, it exceeds others in its simplicity and speed of analysis. This method takes advantage of robotics and automation for a total analysis time of 10 min, including sample preparation, separation, and detection.     

PTV-LV-GC/MS/MS as screening and complementary method to HRMS for the monitoring of dioxin levels in food and feed

Recent developments in trapping efficiency inside ion trap mass spectrometer permitted to lower instrument detection limit (IDL). An IDL of 200 fg μl⁻¹ injected with a signal-to-noise ratio of 5:1 for tetrachlorodibenzo-p-dioxin (TCDD) was obtained by gas chromatography coupled to a quadrupole ion storage mass spectrometer in tandem mode (GC/MS/MS). Coupling large volume programmable temperature vaporizer (PTV-LV) injection to GC/MS/MS provides an alternative and complementary method to classical splitless-GC injection connected to high-resolution mass spectrometry (splitless-GC/HRMS) method for dioxin monitoring in food and feed.

An injection volume of 10 μl was found to be the best compromise between the sensitivity requirements and the robustness required for a high throughput method. PTV-LV-GC/MS/MS and Splitless-GC/HRMS were compared by performing analysis on five different matrices such as beef fat, yolk eggs, milk powder, animal feed and serum samples covering a concentration range of two orders of magnitude (i.e. 0.2–25 ng WHO-TEQ kg⁻¹). An analysis of variance (ANOVA) was carried out. Fisher tests pointed out that the method effect for all the 2,3,7,8 congeners was not significant, indicating that the null hypothesis (H₀: μ₁=μ₂=…=μ_n) was not rejected. Moreover, the interaction effects between methods and matrices were not significant for most of the 2,3,7,8 congeners. However, three congeners (2,3,7,8-TCDF; 1,2,3,4,7,8-HxCDD and 1,2,3,4,6,7,8-HpCDD) were characterized by P-values lower than the significance level (=0.05). In toxic equivalence (TEQ), the study showed that no significant bias was observed between the two methods. Consequently, PTV-LV-GC/MS/MS is an attractive technique and can be used as a cost effective complementary method to HRMS for dioxin levels monitoring in food and feed.     

Development and validation of rapid disequilibrium enzyme-linked immunosorbent assays for the detection of Methyl Yellow and Rhodamine B dyes in foods

Sensitive and specific enzyme-linked immunosorbent assays (ELISAs) were developed for the detection of two illegal synthetic dyes: Methyl Yellow (MY) and Rhodamine B (RB) in food. Polyclonal antibodies were raised against synthesised immunogens and employed in unique direct disequilibrium ELISAs. The time of the assays was only twenty minutes (five minutes for each incubation step with sample and enzyme conjugate and ten minutes with enzyme substrate). The IC(50) for MY was in the range 1.4-4.2 ng mL(-1) and for RB 0.1-0.5 ng mL(-1). A simple sample preparation method was developed for the analysis of a range of sauces. In the case of spices a dispersive solid phase extraction was applied to purify the extracts. The testing of twenty samples took approximately one and a half hours (including sample preparation and analysis). Both assays were validated according to the Commission Decision 2002/657/EC criteria for use in sauces and spices. The detection capability for MY in sauces and spices was determined to be less than 15 ng g(-1) and 50 ng g(-1), respectively and for RB, 10 ng g(-1) for both types of food samples. The precision of the developed assays was determined in a repeatability study. The intra- and inter-assay coefficients of variation were less than 25% for both tests and matrix types. The simplicity and performance of both assays indicate that they will be very reliable screening methods for the detection of the illegal dyes MY and RB in a range of food products.     

Determination of Cry9C protein in processed foods made with StarLink corn

StarLink (Aventis CropScience US) hybrid corn has been genetically modified to contain a pesticidal protein, Cry9C, which makes it more resistant than traditional varieties to certain types of corn insect pests. Unlike other varieties of genetically engineered corn, the U.S. Environmental Protection Agency authorized the use of StarLink corn for animal feed and industrial use only, not for human consumption. However, some Cry9C-containing corn was mistakenly or inadvertently comingled with yellow corn intended for human food use. Because corn containing the Cry9C construct was not approved for human use, the U.S. Food and Drug Administration considers food containing it to be adulterated. Consequently, this regulatory violation resulted in hundreds of recalls of corn-based products, such as taco shells, containing cry9C DNA. Detecting the novel protein in StarLink corn is an emerging issue; therefore, there is no standardized or established analytical method for detecting Cry9C protein in processed foods. We developed a procedure for quantitation of Cry9C protein, with validation data, in processed food matrixes with a limit of quantitation at 1.7 ng/g (ppb), using a commercial polyclonal antibody-based Cry9C kit that was intended for corn grain samples. Intra- and interassay coefficients of variation were 2.8 and 11.8%, respectively. Mean recoveries were 73 and 85% at 2 and 5 ng/g Cry9C fortifications, respectively, for 19 control non-StarLink corn-based matrixes. Our data demonstrate only 0-0.5% of Cry9C protein survived the processing of tortilla chips and soft tortillas made from 100% StarLink corn, resulting in levels from below the detection limit to 45 ppb.     

Validated determination of eight antibiotic substance groups in cattle and pig muscle by HPLC/MS/MS

The described multimethod is suited for the determination of 53 substances of eight antibiotic groups-tetracyclines, quinolones, macrolides, sulfonamides, diphenylsulfones, diamino-pyrimidine derivatives, pleuromutilines, and lincosamides-in cattle and pig muscle. All substances were analyzed simultaneously with the same sample preparation and in one HPLC/MS/MS run. The validation of the multimethod was successfully accomplished with the help of an alternative in-house validation concept requiring only 48 experiments. The substances were validated at concentrations of 0.25, 0.5, 1.0, 1.5, and 2.0 x MRL (maximum residue limit) or 5, 10, 20, 30, and 40 microg/kg for substances without an MRL. The calculated relevant validation parameters were based on and comply with the requirements of Commission Decision 2002/657/EC, i.e., the decision limit, detection capability, repeatability, within-laboratory reproducibility, and recovery. The robustness of the method was demonstrated by varying seven factors of the analytical procedure. Several proficiency tests were carried out successfully to provide evidence for the applicability of the method.     

Validation of short run time LC-ESI (+) MS/MS method for determination of twenty recommended pesticide residues in food based on QuEChERS extraction technique

Food is expected to contain pesticide residues that might have many problems due to their toxicities for human and animals. So, it is very important to detect and quantify the pesticides contamination levels to increase food safety for the human. The target of our study is to analyse a 20 new pesticides including different pesticide classes such as 1 acaricide, 3 fungicides, 2 plant growth regulators, 11 herbicides, 1 insecticide, 1 rodenticide, and 1 metabolite which were selected according to their modern application in the Egyptian agriculture as well as the recommendation of the Egyptian Agriculture Pesticides Committee (APC). The research is focused on the method validation for the routine analysis of the targeted pesticide residues according to the European SANTE/11,813/2017 guideline. The validation was carried out by fortifying of three levels at 0.01, 0.05 and 0.1 mg/kg in four blank matrices: apple, green beans, fennel seeds and rice which represent different classes of food. The most common citrate buffered QuEChERS extraction method and liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS) device were used. The mass spectrometer was operated in the positive electrospray ionisation ESI (+) mode and the non-scheduled multiple reactions monitoring (MRM) method in a short run time of 16.0 min. The limits of quantifications (LOQs) for all pesticides ranged between 0.01 and 0.05 mg/kg. Good linearity of the method was in the concentration range 0.001–0.5 μg/ml with acceptable correlation coefficients (r²) ≥ 0.99 for all analytes. The average recoveries for all the target pesticide residues were in the range of 70–120% with relative standard deviations RSDs ≤ 20%. The matrix effect was compensated by using the standard addition method. This short run time LC ESI (+) MS/MS Method may help laboratories which deal with the routine pesticide residues analysis in different food samples.     

Determination of chloramphenicol in aquatic products by graphene‐based SPE coupled with HPLC‐MS/MS

An effective analytical protocol using graphene‐based SPE coupled with HPLC‐MS/MS for determination of chloramphenicol (CAP) in aquatic products has been developed. In the present work, graphene was evaluated as SPE sorbents for the analytes enrichment and clean up. The target analytes were quantified by a triple‐quadrupole linear ion trap MS in multiple‐reaction monitoring mode. In addition, the proposed method was validated according to Commission Decision 2002/657/EC. The calibration curve was linear over the range of 0.5–100 ng/mL. The mean values of RSD of intra‐ and interday ranging from 1.48 to 4.29% and from 3.25 to 7.42% were obtained, respectively. In the three fortified levels, the recoveries of CAP ranging from 92.3 to 103.4% with RSDs ≤ 5.58% were obtained. The proposed method has been successfully applied to the analysis of CAP in several aquatic product samples, indicating that graphene was a potential SPE sorbent for the enrichment of trace residues in food samples.     

A fast, inexpensive, and safe method for residue analysis of meptyldinocap in different fruits by liquid chromatography/tandem mass spectrometry

An analytical method is reported for residue analysis of the fungicide meptyldinocap in different fruit matrixes that involves extraction with ethyl acetate, hydrolysis of the residues with ethanolamine, and determination by LC/MS/MS. The method involves extraction of 10 g sample with 10 mL ethyl acetate; evaporation of the ethyl acetate phase to dryness, and subsequent hydrolysis of the residues to 4,6-dinitro-2-(1-methylheptyl) phenol on reaction with 1% ethanolamine. The pH of this hydrolyzed product was neutralized with formic acid and analyzed by LC/MS/MS. The hydrolysis reaction followed pseudo-first-order kinetics, and the reaction product was spectroscopically confirmed as 2-(1-methylheptyl)-4,6-dinitrophenol. The method offered > 80% recoveries at an LOQ of 10 ng/g for grape and mango, 25 ng/g for pomegranate with intralaboratory Horwitz ratio < 0.5, and measurement uncertainties < 10% at LOQ levels. Considering first-order rate kinetics, activation energy, enthalpy of activation, and entropy of activation varied as solvent > mango > grape > pomegranate. Free energy of activation at 298 K was higher than at 280 K and was similar for solvent and three matrixes at both temperatures.     

Analytical method for the accurate determination of tricothecenes in grains using LC-MS/MS: a comparison between MRM transition and MS3 quantitation

The current food crisis demands unambiguous determination of mycotoxin contamination in staple foods to achieve safer food for consumption. This paper describes the first accurate LC-MS/MS method developed to analyze tricothecenes in grains by applying multiple reaction monitoring (MRM) transition and MS(3) quantitation strategies in tandem. The tricothecenes are nivalenol, deoxynivalenol, deoxynivalenol-3-glucoside, fusarenon X, 3-acetyl-deoxynivalenol, 15-acetyldeoxynivalenol, diacetoxyscirpenol, and HT-2 and T-2 toxins. Acetic acid and ammonium acetate were used to convert the analytes into their respective acetate adducts and ammonium adducts under negative and positive MS polarity conditions, respectively. The mycotoxins were separated by reversed-phase LC in a 13.5-min run, ionized using electrospray ionization, and detected by tandem mass spectrometry. Analyte-specific mass-to-charge (m/z) ratios were used to perform quantitation under MRM transition and MS(3) (linear ion trap) modes. Three experiments were made for each quantitation mode and matrix in batches over 6 days for recovery studies. The matrix effect was investigated at concentration levels of 20, 40, 80, 120, 160, and 200 μg kg(-1) (n = 3) in 5 g corn flour and rice flour. Extraction with acetonitrile provided a good overall recovery range of 90-108% (n = 3) at three levels of spiking concentration of 40, 80, and 120 μg kg(-1). A quantitation limit of 2-6 μg kg(-1) was achieved by applying an MRM transition quantitation strategy. Under MS(3) mode, a quantitation limit of 4-10 μg kg(-1) was achieved. Relative standard deviations of 2-10% and 2-11% were reported for MRM transition and MS(3) quantitation, respectively. The successful utilization of MS(3) enabled accurate analyte fragmentation pattern matching and its quantitation, leading to the development of analytical methods in fields that demand both analyte specificity and fragmentation fingerprint-matching capabilities that are unavailable under MRM transition.     

QuEChERS法结合高效液相色谱-串联质谱法测定保健食品中12种双酚类化合物

建立了采用高效液相色谱-串联质谱(HPLC-MS/MS)同时测定粉剂、片剂和胶囊剂等保健食品中12种双酚类化合物的检测方法。样品中双酚类化合物经1%(v/v)乙酸乙腈溶液提取,QuEChERS方法净化;12种化合物经Thermo Aquasil C₁₈色谱柱(150 mm×4.6 mm,3.0 μm)分离后,分别在串联质谱正、负离子多反应监测(MRM)模式下检测,基质匹配外标法定量。研究结果表明,在0.5~50.0 μg/kg内,12种双酚类化合物的线性相关系数均大于0.99,方法的检出限(S/N>3)为0.1~0.5 μg/kg,定量限(S/N>10)为0.4~1.7 μg/kg,不同基质的保健食品在3个添加水平(2.0、5.0和10.0 μg/kg)下的回收率为60.5%~116.3%(n=6),相对标准偏差(RSD)为6.8%~11.2%(n=6)。方法操作简单、耗时短、灵敏度高,满足现行法规要求,可实现保健食品中双酚类化合物的定性和定量测定。