A simple method for simultaneous determination of basic dyes encountered in food preparations by reversed-phase HPLC

The present method utilizes a simple pretreatment step, cleanup on polyamide SPE cartridges, and HPLC resolution on reversed-phase C18 for the detection of the three basic nonpermitted dyes encountered in food matrixes. Polyamide cartridges were chosen because both acidic and basic dyes can be cleaned up due to their amphoteric nature. Analysis was performed on a reversed-phase C18 micro-Bondapak column using the isocratic mixture of acetonitrile-sodium acetate with a flow rate of 1.5 mL/min and a programmable lambda(max) specific visible detection to monitor colors, achieving higher sensitivity and expanded scope to test multicolor blends. All the colors showed linearity with the regression coefficient, from 0.9983 to 0.9995. The LOD and LOQ ranged between 0.107 and 0.754 mg/L and 0.371 and 2.27 mg/L or mg/kg, respectively. The intraday and interday precision gave good RSDs, and percentage recoveries in different food matrixes ranged from 75 to 96.5%. The study demonstrates that the use of a combination of a simple SPE cleanup and HPLC resolution with UV-Vis end point detection was successful in screening the presence of these three basic nonpermitted dyes individually or in blend, in a variety of food matrixes.     

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.     

固相萃取-气相色谱-质谱法测定食品中23种邻苯二甲酸酯

建立了同时检测食品中23种邻苯二甲酸酯类化合物的固相萃取-气相色谱-质谱(GC-MS)分析方法。样品经正己烷或乙腈提取、玻璃ProElut PSA固相萃取柱净化,GC-MS选择离子监测模式(SIM)测定。考察了不同种类食品的提取、净化方法。23种邻苯二甲酸酯的线性范围除邻苯二甲酸二异壬酯(DINP)和邻苯二甲酸二异癸酯(DIDP)为0.5～5 mg/L外,其余均为0.05～5 mg/L,相关系数(r)除DIDP外均大于0.99。方法的检出限(信噪比为3)为0.005～0.05 mg/kg,定量限(信噪比为10)为0.02～0.2 mg/kg。在10种食品基质中3个加标水平的平均回收率为77%～112%,相对标准偏差(RSD,n=6)为4.1%～12.5%。该方法稳定、可靠,操作简单,适用于食品中邻苯二甲酸酯类化合物的检测与确证。     

Determination of methylcellulose and hydroxypropyl methylcellulose food gums in food and food products: collaborative study

A collaborative study was performed to determine the reproducibility of a method for the determination of methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) in food. These widely used food gums possess unusual solubility characteristics and cannot accurately be determined by existing dietary fiber methods. The new method uses the enzyme-digestion procedure of AOAC Official Method 991.43. Digestate solutions must be refrigerated to fully hydrate MC or HPMC. The chilled solutions are filtered and analyzed by size-exclusion liquid chromatography. Collaborating laboratories received 28 samples containing MC or HPMC in the range of 0-100%. The sample set included blind duplicates of 5 food matrixes (bread, milk, fish, potato, and powdered juice drink). Cochran and Grubbs tests were used to eliminate outliers. For food samples containing MC, values for within-laboratory precision, repeatability relative standard deviation (RSDr), ranged from 4.2 to 16%, and values for among-laboratories precision, reproducibility relative standard deviation (RSDR), ranged from 11 to 20%. For HPMC samples, RSDr values ranged from 6.4 to 27%, and RSDR values ranged from 17 to 39%. Recoveries of MC and HPMC from the food matrixes ranged from 78 to 101%. These results show acceptable precision and reproducibility for the determination of MC and HPMC, for which no Official AOAC Methods exist. It is recommended that this method be adopted as AOAC Official First Action.     

Evaluation of applied biosystems MicroSeq real-time PCR system for detection of Listeria monocytogenes in food. Performance Tested Method 011002

Increasingly, more food companies are relying on molecular methods, such as PCR, for pathogen detection due to their improved simplicity, sensitivity, and rapid time to results. This report describes the validation of a new Real-Time PCR method to detect Listeria monocytogenes in nine different food matrixes. The complete system consists of the MicroSEQ L. monocytogenes Detection Kit, sample preparation, the Applied Biosystems 7500 Fast Real-Time PCR instrument, and RapidFinder Express software. Two sample preparation methods were validated: the PrepSEQ Nucleic Acid extraction kit and the PrepSEQ Rapid Spin sample preparation kit. The test method was compared to the ISO 11290-1 reference method using an unpaired-study design to detect L. monocytogenes in roast beef, cured bacon, lox (smoked salmon), lettuce, whole cow's milk, dry infant formula, ice cream, salad dressing, and mayonnaise. The MicroSEQ L. monocytogenes Detection Kit and the ISO 11290-1 reference method showed equivalent detection based on Chi-square analysis for all food matrixes when the samples were prepared using either of the two sample preparation methods. An independent validation confirmed these findings on smoked salmon and whole cow's milk. The MicroSEQ kit detected all 50 L. monocytogenes strains tested, and none of the 30 nontargeted bacteria strains.     

气相色谱-质谱法测定聚氯乙烯包装材料和食品模拟物中的46种增塑剂

建立了46种增塑剂在聚氯乙烯(PVC)食品包装材料中的含量及其在水、3%乙酸、10%乙醇和橄榄油4种食品模拟物中迁移量的气相色谱-质谱(GC-MS)测定方法。食品包装材料、水质模拟物和橄榄油中增塑剂分别采用溶解-沉淀法、正己烷液-液萃取和凝胶渗透色谱(GPC)法提取。采用GC-MS法,在选择离子监测模式(SIM)下对46种增塑剂进行定性,采用外标法进行定量测定。各种增塑剂在0.1～2.0 mg/L质量浓度范围内呈线性,相关系数为0.9910～0.9999,各组分检出限均在0.005～0.05 mg/kg之间。在2种食品模拟物中,3个浓度添加水平下46种增塑剂的加标回收率在69.51%～107.21%之间,精密度(RSD, n=6)为3.53%～18.95%。该方法可满足PVC食品接触制品及4种不同性质的食品模拟物中多种类增塑剂的快速筛查和准确定性、定量测定要求。     

Validation of an ultra high pressure liquid chromatographic method for the determination of biologically active amines in food

Biologically active amines include the so called biogenic amines, such as histamine, tyramine and cadaverine, and polyamines such as spermidine and spermine. Ultra high pressure liquid chromatography (UHPLC) is a new generation of separation techniques that takes full advantage of chromatographic principles to increase speed flow which drastically reduce analysis time. The aim of the present work was to validate a rapid method of UHPLC to detect the presence of biogenic amines and polyamines in food. Different food matrixes (wine, fish, cheese, and dry fermented sausage) were used in order to test the versatility of the method. The UHPLC method described in this article has been demonstrated as a reliable procedure to determine 12 biogenic amines and polyamines in less than 7 min of chromatographic elution. The method provides a satisfactory linearity and chromatographic sensitivity with a detection limit lower than 0.2 mg/L and a determination limit falling below 0.3 mg/L for all amines. The precision, in terms of relative standard deviation, was lower than 5% and the accuracy, as mean recovery, was between 93% and 98%, depending on the food matrix.     

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 3-chloro-1,2-propanediol in foods and food ingredients by gas chromatography with mass spectrometric detection: collaborative study

The results of a collaborative study are reported for the determination of 3-chloro-1,2-propanediol (3-monochloropropane-1,2-diol; 3-MCPD) in a wide range of foods and food ingredients, using gas chromatography with mass spectrometric detection and incorporating the use of a deuterated internal standard. After a pretrial study, 12 laboratories (6 United Kingdom, 1 Switzerland, 1 Japan, 2 United States, 1 The Netherlands, and 1 from the European Commission) were asked to analyze 12 test materials (as known duplicates or split-level samples) by using a prescribed procedure. The test materials consisted of duplicate samples of acid-hydrolyzed vegetable protein (containing 3-MCPD at 0.029 mg/kg), malt extract (0.055 mg/kg), wholemeal bread crumbs (0.030 mg/kg), salami (0.016 mg/kg), cheese alternative (0.043 mg/kg), and soup powder (split levels at 0.045 and 0.041 mg/kg). Repeatability ranged from 0.005 to 0.013 mg/kg and reproducibility, from 0.010 to 0.027 mg/kg, for the samples tested. Precision values were well within statistically predicted levels (HORRAT values of <1 for 5 of the 6 matrixes tested) and within method criteria prepared by a joint working group composed of the United Kingdom Ministry of Agriculture, Fisheries and Food and industry representatives. The study demonstrated the satisfactory validation of the method for quantifying 3-MCPD at levels of > or = 0.010 mg/kg. The limit of detection derived from separate in-house studies was estimated to be 0.005 mg/kg. The method was adopted First Action by AOAC INTERNATIONAL.     

固相萃取-气相色谱/质谱法分析水果和蔬菜中残留的嘧菌酯

建立了多种水果和蔬菜中嘧菌酯残留的气相色谱/质谱分析方法。首先用乙酸乙酯-环己烷(体积比为1∶1)对样品中的嘧菌酯进行超声波提取,经硅胶固相萃取小柱对样品提取液进行净化、富集,采用气相色谱/质谱法以选择离子监测模式(m/z 344,372,388,403定性,m/z 344定量)进行检测。实验结果表明,嘧菌酯在0.01～1.0 mg/kg浓度范围内呈线性,其相关系数r>0.99。在低、中、高3个添加水平,嘧菌酯的回收率为85.2%～98.2%,相对标准偏差为5.8%～21.5%。方法的检测限不大于0.01 mg/kg,定量限不大于0.05 mg/kg。     

不同类别食品中21种邻苯二甲酸酯的气相色谱-质谱测定及其分布情况研究

首次建立了同时测定不同类别食品中21种邻苯二甲酸酯的气相色谱-质谱(GC-MS)分析方法.对各种类别的食品采取不同的分离、净化方法;优化了成分复杂的香精或植物提取物等样品的色谱测定条件,通过提取特征离子进行检测和确证,消除了基质干扰,避免产生假阳性结果;探讨了邻苯二甲酸酯类的质谱碎裂机理.21种邻苯二甲酸酯的质量浓度在...     

加速溶剂萃取-凝胶色谱净化高效液相色谱法测定动物源性食品中的胆固醇

采用加速溶剂萃取-凝胶色谱净化建立了动物源性食品中胆固醇检测的高效液相色谱方法。结果表明,胆固醇浓度在1.0~40.0mg/L范围内线性关系良好,加标回收率为89.1%~99.8%,相对标准偏差为3.1%~7.8%。该方法准确、灵敏度高,适用于富含脂类的动物源性食品中胆固醇的检测。     

Simultaneous determination of sorbic and benzoic acids in food dressing by headspace solid-phase microextraction and gas chromatography

A facile headspace solid-phase microextraction (HS-SPME) procedure using 85 microm polyacrylate (PA) fiber is presented for the simultaneous determination of preservatives (sorbic and benzoic acids) in food dressing, including Thousand Island Dressing, HellMANN'S Salad Dressing and Tomato Ketchup, by gas chromatography (GC) with flame ionization detector (FID). The method presented preserves the advantages typical of HS-SPME such as simplicity, low intensity of labor, low cost and solvent free. The main factors affecting the HS-SPME process, such as extraction temperature and time, desorption temperature and time, the acidity and salt concentration of the solution, were optimized. Limits of detection (LODs) of the method were 2.00 microg/L for sorbic acid and 1.22 microg/L for benzoic acid. Relative standard deviations (RSDs) for quintuplicate analyses at three concentration levels of 0.10, 2.0 and 20 mg/L ranged between 3.86 and 14.8%. The method also showed good linearity n a range from 0.02 to 40 mg/L with correlation coefficients (R2) of 0.9986 for sorbic acid and 0.9994 for benzoic acid. Recoveries for the two analytes in all the samples tested ranged from 83.44 to 113.2%. Practical applicability was demonstrated through the simultaneous determination of sorbic and benzoic acids in the three complex samples.     

固相萃取-高效液相色谱-蒸发光散射检测法同时检测食品中5种人工合成甜味剂

建立了高效液相色谱-蒸发光散射检测仪(HPLC-ELSD)同时检测食品中安赛蜜、糖精钠、甜蜜素、三氯蔗糖和阿斯巴甜5种甜味剂的方法。甜味剂经0.1%(v/v)甲酸缓冲液提取后,利用C18固相萃取小柱净化浓缩,以3 μm C18柱为分离柱,0.1%(v/v)甲酸(氨水调节pH=3.5)-甲醇(61:39, v/v)为流动相,经高效液相色谱法分离,蒸发光散射检测器进行检测。结果表明,5种甜味剂在30～1000 mg/L的范围内,具有良好的线性关系(相关系数大于0.997);在3个添加水平下,样品的平均回收率为85.6%～109.0%,相对标准偏差小于4.0%;方法检出限(LOD,信噪比(S/N)=3)分别为安赛蜜2.5 mg/L、糖精钠3 mg/L、甜蜜素10 mg/L、三氯蔗糖2.5 mg/L及阿斯巴甜5 mg/L。该方法简单、灵敏、操作成本低,可用于不同形态食品中多种甜味剂的同时检测。     

衍生化气相色谱-质谱法测定玩具和食品接触材料中双酚A

建立了玩具和与食品接触的材料中双酚A的衍生化气相色谱-质谱(GC-MS)检测方法。通过索氏萃取富集样品中的双酚A,与乙酸酐反应,终产物用GC-MS进行测定。优化了衍生化时间、衍生化试剂用量等衍生化条件。在最佳条件下,双酚A衍生物稳定且峰形良好,在0.05～50 mg/L范围内,相关系数(r2)在0.999以上。在0.05、1.00、10.00 mg/kg 3个添加水平下,双酚A的加标回收率为80%～93%,相对标准偏差(RSD)均小于3.7%;检出限(以信噪比(S/N)=3计)为10 μg/kg。该方法精密度好、回收率高,可用于玩具和食品接触材料中双酚A的定量检测。     

Liquid chromatographic determination of residual nitrite/nitrate in foods: NMKL collaborative study

Nitrite and nitrate are used as additives in the food industry to provide color and taste and to control undesirable gas and flavor production by anaerobic bacteria by virtue of their antimicrobial properties. The analytical method that has been widely used to determine nitrite and nitrate involves the use of toxic cadmium. In response to a request from the Nordic Committee on Food Analysis, a study was performed to obtain an alternative chromatographic method to determine residual nitrite and nitrate in meat products. The study was done in 3 stages: (1) comparative evaluation of the performance of 3 liquid chromatographic methods, (2) internal validation of the selected ion chromatographic method, and (3) a collaborative study in which 17 laboratories from European countries participated. Furthermore, the applicability of the method to matrixes other than meat and meat products was demonstrated. The results of the collaborative study show that the European Prestandard prENV 12014-4 is well suited for the determination of nitrite and nitrate in different foods (e.g., meat products, vegetables, baby food, and cheese). The limits of detection for nitrite and nitrate ions are 1 and 10 mg/kg, respectively. Recoveries of residual nitrite/nitrate ranged from 96 to 108%. Repeatability and reproducibility were satisfactory.     

高效液相色谱-串联质谱法测定食品中20种氨基甲酸酯类农药残留

建立了食品中20种氨基甲酸酯类农药残留量的高效液相色谱-串联质谱联用(HPLC-MS/MS)测定与确证方法。20种氨基甲酸酯类农药在0.005～0.1 mg/kg范围内线性良好,相关系数为0.991 7～0.999 6;在0.005～0.025 mg/kg范围内, 20种目标物的回收率为51.2%～125.0%,相对标准偏差为1.4%～19.8%。该方法准确、灵敏、快速,可满足国际上对食品中这20种氨基甲酸酯类农药残留量的检测需要。     

Simultaneous determination of thirteen polycyclic aromatic hydrocarbons and twelve aldehydes in cooked food by an automated on-line solid phase extraction ultra high performance liquid chromatography tandem mass spectrometry

An on-line solid phase extraction (SPE) ultra high performance liquid chromatography tandem mass spectrometry method has been developed for the simultaneous identification and determination of thirteen polycyclic aromatic hydrocarbons (PAHs) and twelve aldehydes (derivatized with 2,4-dinitrophenylhydrazine). The chromatographic conditions have been optimized to obtain the maximum of sensitivity and resolution taking into account the different retention interactions and the different ionization conditions of PAHs and derivatized aldehydes. LOD values ranging from 0.028 to 0.768 μg L(-1) for PAHs and from 0.002 to 0.125 μg L(-1) for aldehydes were obtained. The resolution permitted the separation of four couples of PAH isomers. Sample pre-treatment and SPE were optimized in order to apply the whole methodology to the analysis of different food matrices as salmon, frankfurter, steak, and pork chop, subjected to different cooking modes (smoked, grilled, cooked in oil or in butter). Particular attention was devoted to the evaluation of matrix effect that was significantly reduced through the on-line SPE treatment. For each food matrix the method detection limits, the method quantitation limits, and the recovery R were evaluated. R was shown not to depend on analyte concentration in the explored concentration range (LOQ - 50.000 μg L(-1)): the average R percent ranges from 70.6% to 120.0%.     

Determination of semicarbazide in baby food by liquid chromatography/tandem mass spectrometry: interlaboratory validation study

An interlaboratory validation study funded by the European Commission, Directorate General for Health and Consumer Protection (DG SANCO), was conducted to evaluate the effectiveness of a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the determination of semicarbazide (SEM) in different types of baby food at a possible future European regulatory limit (10 ng/g). The test portion of the sample was extracted with hydrochloric acid, and the analyte was derivatized with 2-nitrobenzaldehyde, with 1,2-[15N2, 13C] SEM as an internal standard. The extract was neutralized and then purified on a solid-phase extraction cartridge. The SEM was determined by reversed-phase LC with detection by MS/MS. Apple puree, rice pudding, and meat/vegetable meal baby food materials, spiked with SEM at levels of about 3, 10, and 30 ng/g, respectively, were sent to 20 laboratories in 12 different European countries, which submitted results from 17 participants. Recoveries ranged from 88.8 to 106.1%. Based on results for spiked samples (blind pairs at 3 levels), the relative standard deviations for repeatability (RSDr) ranged from 4.2 to 6.9% and the relative standard deviations for reproducibility (RSDR) ranged from 16.6 to 24.3%. The method showed acceptable within- and between-laboratory precision for all 3 matrixes, as evidenced by HorRat values, at the target levels for the determination of SEM.     

A solid-phase microextraction GC/MS/MS method for rapid quantitative analysis of food and beverages for the presence of legally restricted biologically active flavorings

A method was developed using automated headspace solid-phase microextraction coupled with GC/MS/MS to simultaneously determine the presence of seven biologically active flavoring substances whose levels of use in processed foods is controlled by statutory limits. The method can be applied to identify and quantify the presence of 1,2-benzopyrone (coumarin), beta-asarone, 1-allyl-4-methoxybenzene (estragole), menthofuran, 4-allyl-1 ,2-dimethoxybenzene (methyl eugenol), pulegone, and thujone at levels ranging from 0.5 to 3000 mg/kg. The method has been optimized and validated for three different generic food types categorized on the basis of composition and anticipated use levels of flavorings and food ingredients. The food categories are alcoholic and nonalcoholic beverages; semisolid processed foods (e.g., soups, sauces, confectionary, etc.); and solid foods (muesli, bakery products, etc.). The method is simple, inexpensive, and rapid, and eliminates the use of flammable and toxic solvents. There is no sample preparation, and using MSIMS, unequivocal confirmation of identification is achieved even in highly complex matrixes containing many potential interfering volatiles. The method precision for spiked samples ranged from 2 to 21%, with the greatest variability associated with solid matrixes. The LOD and LOQ values were well below 0.1 and 0.5 mg/kg, respectively, in all cases for individual substances, fulfilling requirements for enforcement purposes. The robustness of the method was demonstrated in a small survey of retail samples of four spirits, five flavored milks, three energy drinks, five liqueurs, five soups, 10 sauces, five herbal teas, and three breakfast cereals.