Shaun MacMahon

A liquid chromatography–tandem mass spectrometry method for the detection of economically motivated adulteration in protein-containing foods

A new analytical method was developed to determine the presence of six (6) compounds with the potential to be used in economic adulteration to enhance the nitrogen content in milk products and bulk proteins. Residues were extracted from the matrix with 2% formic acid, after which acetonitrile (ACN) was added to induce precipitation of the proteins. Extracts were analyzed by liquid chromatography using a ZIC-HILIC column with tandem mass spectrometry (LC-MS/MS) using electrospray ionization (ESI). Single-laboratory method validation data was collected in six matrices fortified at concentrations down to 1.0 μg/g (ppm). Average recoveries and average relative standard deviations (RSD) using spiked matrix calibration standard curves were the following: cyromazine (CY) 95.9% (7.5% RSD), dicyandiamide (DC) 98.1% (5.6% RSD), urea 102.5% (8.6% RSD), biuret (BU) 97.2% (6.6% RSD), triuret (TU) 97.7% (5.7% RSD), and amidinourea (AU) 93.4% (7.4% RSD). This method provides a rapid and effective approach to proactively combat economically motivated adulteration in protein-containing products.

Occurrence of 3-MCPD and glycidyl esters in edible oils in the United States

Fatty acid esters of 3-monochloropropanediol (3-MCPD) and glycidol are processing contaminants found in a wide range of edible oils. While both 3 MCPD and glycidol have toxicological properties that at present has concerns for food safety, the published occurrence data are limited. Occurrence information is presented for the concentrations of 3-MCPD and glycidyl esters in 116 retail and/or industrial edible oils and fats using LC-MS/MS analysis of intact esters. The concentrations for bound 3-MCPD ranged from below the limit of quantitation (<LOQ) to 0.09 mg kg−1 (ppm) in 22 unrefined oils and from 0.005 to 7.2 mg kg−1 (ppm) in 94 refined oils. The concentrations for bound glycidol ranged from <LOQ to 0.03 mg kg−1 (ppm) in unrefined oil samples and from <LOQ to 10.5 mg kg−1 (ppm) in processed oil samples. The highest concentrations for both 3-MCPD and glycidol were seen in refined palm oil and palm olein samples. Palm olein samples also contained a higher percentage of 3-MCPD in mono-ester form than any other type of oil.

Analysis of Processing Contaminants in Edible Oils. Part 1. Liquid Chromatography–Tandem Mass Spectrometry Method for the Direct Detection of 3-Monochloropropanediol Monoesters and Glycidyl Esters

A new analytical method has been developed and validated for the detection of glycidyl esters (GEs) and 3-monochloropropanediol (3-MCPD) monoesters in edible oils. The target compounds represent two classes of potentially carcinogenic chemical contaminants formed during the processing of edible oils. Target analytes are separated from edible oil matrices using a two-step solid-phase extraction (SPE) procedure. The extracts are then analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). Chromatographic conditions that separate sn-1 and sn-2 monoesters of 3-MCPD have been developed for the first time. The method has been validated for GEs, sn-1 3-MCPD monoesters of lauric, myristic, linolenic, linoleic, oleic, and stearic acids, and sn-2 3-MCPD monoesters of oleic and palmitic acids in coconut, olive, and palm oils using an external calibration curve. The range of average recoveries and relative standard deviations (RSDs) across the three oil matrices at three spiking concentrations are 84-115% (3-16% RSD) for the GEs, 95-113% (1-10% RSD) for the sn-1 3-MCPD monoesters, and 76.8-103% (5.1-11.2% RSD) for the sn-2 3-MCPD monoesters, with limits of quantitation at or below 30 ng/g for the GEs, 60 ng/g for sn-1 3-MCPD monoesters, and 180 ng/g for sn-2 3-MCPD monoesters.

Application of single immunoaffinity clean-up for simultaneous determination of regulated mycotoxins in cereals and nuts

A rapid and sensitive analytical strategy for the simultaneous determination of twelve mycotoxins (aflatoxins, fumonisins, zearalenon, deoxynivalenol, ochratoxin A, T-2 and HT-2 toxins) using ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) was developed and validated. The method was validated for peanuts, barley and maize-breakfast cereals; selected as they represent the matrices most often contaminated by mycotoxins. The method is designed for fast and reliable analyses of mycotoxins in regulatory, industrial and private laboratories. Multi-target immunoaffinity columns containing antibodies for all mycotoxins studied herein were used for sample clean-up. Method optimization was predominantly focused on the simplification of extraction and clean-up procedure recommended by column producers. This newly developed and simplified procedure decreased both the sample preparation time and the solvent volumes used for their processing. The analysis of all regulated mycotoxins was conducted by a newly developed UHPLC-MS/MS method with a sample run time of only ten minutes. The method trueness was tested with analytical spikes and certified reference materials, with recoveries ranging from 71% to 112% for all of the examined mycotoxins.

Analysis of processing contaminants in edible oils. Part 2. Liquid chromatography-tandem mass spectrometry method for the direct detection of 3-monochloropropanediol and 2-monochloropropanediol diesters.

A method was developed and validated for the detection of fatty acid diesters of 2-monochloropropanediol (2-MCPD) and 3-monochloropropanediol (3-MCPD) in edible oils. These analytes are potentially carcinogenic chemical contaminants formed during edible oil processing. After separation from oil matrices using a two-step solid-phase extraction (SPE) procedure, the target compounds are quantitated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). The first chromatographic conditions have been developed that separate intact diesters of 2-MCPD and 3-MCPD, allowing for their individual quantitation. The method has been validated for 28 3-MCPD diesters of lauric, myristic, palmitic, linolenic, linoleic, oleic, and stearic acids in coconut, olive, and palm oils, as well as 3 2-MCPD diesters, using an external calibration curve. The range of average recoveries and relative standard deviations (RSDs) across the three oil matrices at three spiking concentrations are 88-118% (2-16% RSD) with maximum limits of quantitation of 30 ng/g (ppb).

Identification of unknown compounds from polyester cans coatings that may potentially migrate into food or food simulants.

Cross-linked polyester resins are being introduced into the market as alternatives to epoxy resins as coatings for metal food cans. Identification of potential migrants, from these coatings into food, is a significant analytical challenge due to the diversity of substances employed in the manufacture of the coatings. However, such identification is required to assess migration from the can coating into the food and quantify dietary exposure. Polyester can coatings were extracted with acetonitrile at 40°C for 24h and the extracts were analyzed by a variety of analytical techniques, including GC-MS, HPLC-DAD/MS, HPLC-DAD/CAD and UHPL C-HRMS. Twenty nine non-volatile oligomers were tentatively identified using retention times, UV spectra, and accurate mass measurements. Identified oligomers suggest the coating in use for food cans is a polyester coating and is mainly based on the monomers isophthalic acid, terephthalic acid and nadic acid. To give confidence in the identification, one of the tentatively identified oligomer was synthetized and analyzed by (13)C and (1)H NMR and UHPL C-HRMS. The NMR and HRMS results, confirmed the presence of this compound in the can extracts. Finally, to determine if rapid, direct detection of the oligomers was practical, the coatings were analyzed by DART-HRMS. Twenty three out of the 29 oligomers were identified in the coating by direct measurement with DART-HRMS in few minutes.

Development of a liquid chromatography-tandem mass spectrometry method for the determination of sulfite in food.

Sulfites are widely used food preservatives that can cause severe reactions in sensitive individuals. As a result, the U.S. FDA requires that sulfites be listed on the label of any food product containing >10 mg/kg (ppm) sulfite (measured as sulfur dioxide). Currently, the optimized Monier-Williams (MW) method (AOAC Official Method 990.28) is the most common approach for determining sulfite concentrations in food samples. However, this method is time-consuming and lacks specificity in certain matrices. An improved rapid, sensitive, and selective method has been developed using electrospray ionization (ESI) high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of sulfite in various food matrices. A total of 12 different types of foods were evaluated. These included dried fruits and vegetables, frozen seafood, sweeteners, and juices. The matrix is extracted with a buffered formaldehyde solution, converting free and reversibly bound sulfite to the stable formaldehyde adduct, hydroxymethylsulfonate (HMS). Extracts are prepared for injection using a C18 SPE cartridge to remove any lipophilic compounds. HMS is then separated from other matrix components using hydrophilic interaction chromatography (HILIC) and detected using multiple reaction monitoring (MRM). The method was validated at 5 concentrations in 12 food matrices. Accuracy data showed spiked recoveries ranging from 84 to 115% in representative foods. Six commercially available sulfited products were analyzed using the LC-MS/MS method, as well as the MW method, to determine if differences exist.

Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS) Method for the Direct Detection of 2-Monochloropropanediol (2-MCPD) Esters in Edible Oils

A new analytical method has been developed and validated for the detection and quantification of 2-monochloropropanediol (2-MCPD) esters in edible oils. The target compounds are potentially carcinogenic contaminants formed during the processing of edible oils. As the 2-MCPD esters that occur most frequently in refined edible oils were not commercially available, standards were synthesized with identity and purity (95+%) confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and (1)H NMR. Target analytes are separated from edible oil matrices using a two-step solid-phase extraction (SPE) procedure. The extracts are then analyzed using LC-MS/MS with electrospray ionization (ESI). The method has been validated for 11 2-MCPD diesters and 3 2-MCPD monoesters in soybean oil, olive oil, and palm oil using an external calibration curve. The ranges of average recoveries and relative standard deviations (RSD) across the three oil matrices at three spiking concentrations are 79-106% (3-13% RSD) for the 2-MCPD diesters and 72-108% (4-17% RSD) for the 2-MCPD monoesters, with limits of quantitation at or below 30 ng/g for the diesters and 90 ng/g for the monoesters.

Occurrence of 3-monochloropropanediol esters and glycidyl esters in commercial infant formulas in the United States

ABSTRACT This work presents occurrence data for fatty acid esters of 3-chloro-1,2-propanediol (3-MCPD) and glycidol in 98 infant formula samples purchased in the United States. These contaminants are considered potentially carcinogenic and/or genotoxic, making their presence in refined oils and foods a potential health risk. Recently, attention has focused on methodology to quantify MCPD and glycidyl esters in infant formula for risk-assessment purposes. Occurrence data for 3-MCPD and glycidyl esters were produced using a procedure for extracting fat from infant formula and an LC-MS/MS method for analysing fat extracts for intact esters. Infant formulas were produced by seven manufacturers, five of which use palm oil and/or palm olein in their formulations. In formulas containing palm/palm olein, concentrations for bound 3-MCPD and glycidol ranged from 0.021 to 0.92 mg kg–1 (ppm) and from < LOQ to 0.40 mg kg–1 (ppm), respectively. Formulas not containing palm/palm olein, bound 3-MCPD and glycidol concentrations ranged from 0.072 to 0.16 mg kg–1 (ppm) and from 0.005 to 0.15 mg kg–1 (ppm), respectively. Although formulas from manufacturers A and G did not contain palm/palm olein, formulas from manufacturer E (containing palm olein) had the lowest concentrations of bound 3-MCPD and glycidol, demonstrating the effectiveness of industrial mitigation strategies. Graphical Abstract

Method development and survey of Sudan I–IV in palm oil and chilli spices in the Washington, DC, area

ABSTRACT Sudan I, II, III and IV dyes are banned for use as food colorants in the United States and European Union because they are toxic and carcinogenic. These dyes have been illegally used as food additives in products such as chilli spices and palm oil to enhance their red colour. From 2003 to 2005, the European Union made a series of decisions requiring chilli spices and palm oil imported to the European Union to contain analytical reports declaring them free of Sudan I–IV. In order for the USFDA to investigate the adulteration of palm oil and chilli spices with unapproved colour additives in the United States, a method was developed for the extraction and analysis of Sudan dyes in palm oil, and previous methods were validated for Sudan dyes in chilli spices. Both LC-DAD and LC-MS/MS methods were examined for their limitations and effectiveness in identifying adulterated samples. Method validation was performed for both chilli spices and palm oil by spiking samples known to be free of Sudan dyes at concentrations close to the limit of detection. Reproducibility, matrix effects, and selectivity of the method were also investigated. Additionally, for the first time a survey of palm oil and chilli spices was performed in the United States, specifically in the Washington, DC, area. Illegal dyes, primarily Sudan IV, were detected in palm oil at concentrations from 150 to 24 000 ng ml–1. Low concentrations (< 21 µg kg–1) of Sudan dyes were found in 11 out of 57 spices and are most likely a result of cross-contamination during preparation and storage and not intentional adulteration.