Improved and simplified liquid chromatography/atmospheric pressure chemical ionization mass spectrometry method for the analysis of underivatized free amino acids in various foods

An improved analytical method which offers rapid, accurate determination and identification of 22 amino acids in a variety of matrices, e.g. baby foods, juices, honey is reported. The amino acids were extracted from the matrixes using acidified water. Simultaneous determination of 22 underivatized amino acids was carried out by a liquid chromatography-mass spectrometry (LC/MS). A narrow-bore column allowed rapid screening and quantitative analysis by positive LC/atmospheric pressure chemical ionization (APCI) MS with only acidified mobile phase. Retention times of the 22 amino acids were in the range of ca. 0.9-7.5 min. Sample preparation without clean-up followed by fast chromatographic analysis allowed the analysis to be completed in < 25 min

Determination of Fumonisins B-1 and B-2 in Corn by LC/MS with Immunoaffinity Column Cleanup: Interlaboratory Study

An interlaboratory validation study was conducted to establish the method performance characteristics of an immunoaffinity column (IAC) cleanup procedure followed by LC/MS for the determination of fumonisins B-1 (FB1) and B-2 (FB2) and combined FB1 + FB2 in corn. The test portion is extracted with acetonitrile methanol water (25 + 25 + 50). The extract is filtered, diluted with phosphate-buffered saline solution, and applied to an IAC. FB1 and FB2 are removed with methanol, followed by water, then directly determined by RPLC with MS detection using selected-ion monitoring of two characteristic ions in each case. Naturally contaminated corn samples were milled to a fine powder and mixed to produce three samples with target levels of combined FB1 + FB2 ranging from 350 to 4000 mu g/kg. Of 15 initially participating laboratories, two failed to report results and another did not follow the prescribed method. Thus, valid results were obtained from 12 participants located in 11 countries. Statistical analysis of the results produced RSDr values of 4.6-11.9, 1.9-12.6, and 1.4-11.5% for FB1, FB2, and combined FBI + FB2, respectively; the corresponding RSDR values were 19.8-23.8, 18.2-25.5, and 18.8-23.2%. The three concentration levels of combined FB1 + FB2 were 534, 1194, and 1954 mu g/kg. HorRat values for r and R were all <2.0, indicating that the method is suitable as a regulatory method for the enforcement of European Union limits for fumonisins in corn

Detection of porcine DNA in gelatine and gelatine-containing processed food products-Halal/Kosher authentication

A commercially available real-time PCR, based on a multi-copy target cytochrome b (cyt b) using porcine specific primers, has been validated for the Halal/Kosher authentication of gelatine. Extraction and purification of DNA from gelatine were successfully achieved using the Surefood (R) PREP Animal system, and real-time PCR was carried out using SureFood (R) Animal ID Pork Sens kit. The minimum level of adulteration that could be detected was 1.0% w/w for marshmallows and gum drops. A small survey was undertaken of processed food products such as gum drops, marshmallows and Turkish delight, believed to contain gelatine. Of fourteen food products from Germany, two samples were found to contain porcine gelatine, whereas of twenty-nine samples from Turkey twenty-eight were negative. However, one product from Turkey contained porcine DNA and thus was not Halal, and neither was the use of porcine gelatine indicated on the product label

Coupled Turbulent Flow Chromatography: LC-MS/MS Method for the Analysis of Pesticide Residues in Grapes, Baby Food and Wheat Flour Matrices

This paper describes an on-line sample preparation method for the simultaneous determination of 48 pesticides in grapes, baby food and wheat flour matrices. Target pesticides were selected to represent a wide variety of chemical structures and three typical matrices were selected. Turbulent flow chromatography was applied for on-line sample cleanup directly coupled to LC-MS/MS. The aim of the method was to reduce total analysis time, eliminate manual laboratory work, provide clean extracts and achieve reproducible results. Single laboratory method validation was conducted establishing limits of detection between 0.8 and 6.0 ng g(-1) for baby food, and 0.8-10.3 ng g(-1) for other matrices. Within-day precision values varied between 4 and 18 %, while between-day precisions were in the range 5-22 %. Method recovery ranged from 67 to 124 %, and method accuracy was demonstrated by analysis of external quality control samples. The method was also tested on 24 different survey samples from both bio and organic origin. The method was shown to be convenient, fast and fit for purpose in meeting regulatory requirements for pesticide residue monitoring

Future perspectives in Orbitrap (TM)-high-resolution mass spectrometry in food analysis: a review

A literature search from 2007 to 2014 was conducted to identify publications where principally LC-Orbitrap-high-resolution mass spectrometry (HRMS) has been employed in food analysis. Of a total of 212 relevant references, only 22 papers were from 2007-10, but in subsequent years there has been a steady growth in publications with 38-55 relevant papers being published each year from 2011 to 2014. In the food safety area, over 50% of the published papers were equally divided between pesticides, veterinary drug residues and natural toxins (including mycotoxins) focused primarily on multi-analyte target analysis. LC-Orbitrap-HRMS was also found to be increasingly important for the analysis of bioactive substances, principally phenolic compounds in foods. A number of studies reported for the first time the identification of new fungal metabolites, predominantly various conjugated forms of known mycotoxins. Novel process contaminants were also identified by LC-Orbitrap-HRMS, as were various substances used for food adulteration and bioactive substances in herbal products and dietary supplements. Untargeted analysis is seen as a major future trend where HRMS plays a significant role. Retrospective analysis of scanned high-resolution mass spectra in conjunction with relevant databases can provide new insights. Metabolomics is also being increasingly used where foods are being profiled through fingerprinting using HRMS. All evidence points towards future growth in the number of applications of HRMS in food safety and quality, as the power of this technique gains wider recognition

Meat species identification and Halal authentication using PCR analysis of raw and cooked traditional Turkish foods

The method performance characteristics of commercially available PCR kits for animal species identification were established. Comminuted meat products containing different levels of pork were prepared from authentic beef, chicken, and turkey. These meat products were analysed in the raw state and after cooking for 20 mm at 200 degrees C. For both raw and cooked meats, the PCR kit could correctly identify the animal species and could reliably detect the addition of pork at a level below 0.1%. A survey of 42 Turkish processed meat products such as soudjouk, salami, sausage, meatball, cured spiced beef and doner kebap was conducted. Thirty-six samples were negative for the presence of pork (<0.1%) and four were found to be correctly labelled as containing pork. However, one sausage sample was labelled as containing 5% beef, but beef DNA was not detected and a meatball sample labelled as 100% beef was found to contain chicken. Another turkey meatball sample was predominantly chicken

Immunoaffinity Column Cleanup with Liquid Chromatography Using Postcolumn Bromination for the Determination of Aflatoxins in Black and White Sesame Seed: Single-Laboratory Validation

A single-laboratory validation was conducted to establish the effectiveness of an immunoaffinity column cleanup procedure followed by LC with fluorescence detection for the determination of aflatoxins B-1, B-2, G(1), and G(2) in sesame seeds. The sample is homogenized with 50% water (w/w) to form a slurry, then the test portion is extracted with methanol-water (60 + 40, v/v) using a high-speed blender. The sample extract is filtered, diluted with 15% Tween 20 in phosphate-buffered saline solution, and applied to an immunoaffinity column. Aflatoxins are removed with neat methanol, then directly determined by RP-LC with fluorescence detection using postcolumn bromination (Kobra cell). Test portions of blank white sesame seed slurry were spiked with a mixture of aflatoxins to give total levels of 4 and 10 mu g/kg. Recoveries for individual and total aflatoxins ranged from 92.7 to 110.3% for spiked samples. Based on results for spiked sesame paste (triplicates at two levels), the RSD for repeatability (RSDr) averaged 1.1% for total aflatoxins and 1.4% for aflatoxin B-1. The method was demonstrated to be applicable to naturally contaminated samples of black and white sesame seeds obtained from local markets in China

A critical review of the specifications and performance of antibody and DNA-based methods for detection and quantification of allergens in foods

Despite the availability of a large number of antibody and DNA based methods for detection and quantification of allergens in food there remain significant difficulties in selecting the optimum technique to employ. Published methods from research groups mostly contain sufficient detail concerning target antigen, calibration procedures and method performance to allow replication by others. However, routine allergen testing by the food industry relies upon commercialised test kits and frequently the suppliers provide disappointingly little specification detail on the grounds that this is proprietary information. In this review we have made a critical assessment of the published literature describing the performance of both commercial and non-commercial test kits for food allergens over the period 2008-2018. Mass spectrometric methods, which have the potential to become reference methods for allergens, are not covered in this review. Available information on the specifications of commercial ELISA and LFD test kits are tabulated for milk, egg and peanut allergens, where possible linking to publications concerning collaborative studies and proficiency testing. For a number of commercial PCR test kits, specifications provided by manufacturers for detection of a small selection of allergen are tabulated. In conclusion we support the views of others of the critical need for allergen reference materials as the way forward to improve the comparability of different testing strategies in foods

Determination of fumonisins B-1 and b2 in corn by liquid chromatography/mass spectrometry with immunoaffinity column cleanup: Single-laboratory method validation

A single-laboratory method validation was conducted to establish the effectiveness of an immunoaffinity column cleanup procedure followed by liquid chromatography/mass spectrometry (LC/MS) for the determination of fumonisins B-1 and B-2 (FB1 + FB2) in corn. The test portion is extracted with acetonitrile-methanol-water (25 + 25 + 50). The extract is filtered, diluted with phosphate-buffered saline solution, and applied to an immunoaffinity column. FB1 + FB2 are removed with methanol and directly determined by reversed-phase LC with MS detection using selected-ion monitoring of 2 characteristic ions in each case. Test portions of blank corn samples were spiked with a mixture of FB1 + FB2 to give total levels of 200 and 500 ng/g, respectively. Recoveries of both FB1 and FB2 from spiked samples averaged 90.4-101%. Based on results for spiked raw corn (triplicates at 2 levels), the relative standard deviation for repeatability ranged from 2.8 to 7.1%. The accuracy of the method was demonstrated by analysis of Food Analysis Performance Assessment Scheme (FAPAS (R)) test material. The method was also applied to a small survey of processed corn products such as corn chips, cornflakes, and popcorn

Analysis of Deoxynivalenol, Zearalenone, T-2, and HT-2 Toxins in Animal Feed by LC/MS/MS-A Critical Comparison of Immunoaffinity Column Cleanup with No Cleanup

A comparison has been made of an LC/MS/MS method using direct analysis of acetonitrile extracts of feed and cereal samples and a method using acetonitrile extraction and subsequent immunoaffinity column (IAC) cleanup. Naturally contaminated samples containing one or more of deoxynivalenol, zearalenone, T-2, and HT-2 toxins were analyzed together with test materials containing known toxin levels. LC/MS/MS ion ratios and peak profiles, repeatability, and LOQs were used as the basis for comparing the two approaches. The method without cleanup had poorer performance than the method with IAC cleanup in terms of identification based on ion ratios compared to standards. Without cleanup, there was more evidence of background interference, and monitored ions were invariably seen against a noisy background. Nevertheless, quantification of samples analyzed without cleanup gave reasonable agreement with the levels found in the same samples that had received IAC cleanup. Repeatability was poorer with no cleanup, and LOQ values were higher for HT-2 and 1-2 toxins, but there was no evidence of any adverse effects on MS performance with repeated injections of crude extracts. Overall, it was concluded that LC/MS/MS analysis of samples with no cleanup is adequate for screening, but for definitive measurements (e.g., for food regulatory control purposes) IAC cleanup remains essential