Melamine contamination in milk powder in Uruguay

Forty samples of milk powder purchased in Uruguay were analysed to assess melamine (MEL) levels. Trichloroacetic acid and acetonitrile were used to extract and precipitate milk proteins previously to clean up of the samples by solid-phase extraction and then were determined by liquid chromatography coupled to ultraviolet detection. The limit of detection (LOD) and limit of quantification (LOQ)of MEL were 0.006 and 0.019 mg kg^?1, respectively. Milk was fortified with MEL at three levels, producing average recoveries higher than 83.8%. The values for positive samples ranged from 0.017 to 0.082 mg kg^?1. Nine samples were positive. Three of them had concentrations between LOD and LOQ. The mean MEL contamination was 0.028 mg kg^?1. Consumption of milk powder containing these levels of MEL does not constitute a health risk for consumers.     

Determination of phthalate sum in fatty food by gas chromatography

Presented method for determination of sum of phthalates is based on their alkaline hydrolysis to phthalic acid at 80 °C for 20 h, followed by the selective extraction of lipophilic interferents from acidified hydrolysate at pH 1 with n-hexane. Phthalic acid is derivatized to dimethyl phthalate (DMP) with diazomethane in aqueous-chloroform two-phase system. Resulting DMP is absorbed in chloroform and determined by GC-FID. Method calibration resulted in LOD and LOQ of 0.4 (2.1) and 1.2 (6.2) μg g⁻¹ (nmol g⁻¹) DMP, respectively. Real samples of Baltic herring and codfish, butter, pork, goose and duck fats, sunflower, olive, rapeseed and linseed oils were analysed and the background corrected total phthalates content was found in the range from not detected level in duck fat to 12.5 (64.3) μg g⁻¹ (nmol g⁻¹) in butter, respectively.     

LC-TOF/MS determination of phthalates in edible salts from food markets in Korea

Residual quantities of 12 phthalates have been monitored in edible salts (raw salts, refined salts, refined salts with additives and baked salts) available in Korean food markets. Liquid–liquid extraction followed by liquid chromatography time-of-flight mass spectrometry (LC-TOF/MS) was used to analyse the samples. The method was validated and showed linear correlation (R ² > 0.996) in the range 0.5–100 ng g^?1 for all target analytes. Recoveries were 85.9–108.4%, except for diethyl phthalate (DEP). Relative standard deviations (RSDs) were 2.7–6.0% and the limits of detection (LODs) were 1.2–2.8 ng g^?1. Although the contamination of phthalates in salt would be trivial in comparison to those of other main foods and below the reference dose of the Chronic Oral Exposure recommended by US-EPA, the availability of reference data could be valuable for food chemists and salt manufacturers.     

Di-(2-ethylhexyl) adipate and 20 phthalates in composite food samples from the 2013 Canadian Total Diet Study

A sensitive and selective GC-MS method was developed and used for simultaneous analysis of di-(2-ethylhexyl) adipate (DEHA) and 20 selected phthalates in the food samples from the 2013 Canadian Total Diet Study. At least one of the 21 target chemicals was detected in 141 of the 159 different food composite samples analysed. However, only seven of the 21 target chemicals were detected, with di-(2-ethylhexyl) phthalate (DEHP) and DEHA being detected most frequently, in 111 and 91 different food composite samples, respectively, followed by di-n-butyl phthalate (DBP) (n = 44), n-butyl benzyl phthalate (BBzP) (32), di-iso-butyl phthalate (DiBP) (27), di-ethyl phthalate (DEP) (3), and di-cyclohexyl phthalate (DCHP) (1). Levels of DEP (di-ethyl phthalate), DiBP, DBP, BBzP and DCHP were low, in general, with average concentrations of 9.63, 8.26, 23.2, 12.4 and 64.9 ng g^–1, respectively. Levels of DEHA and DEHP varied widely, ranging from 1.4 to 6010 ng g^–1 and from 14.4 to 714 ng g^–1, respectively. High levels of DEHA were found mainly in the composite samples where the individual food items used to prepare the composite were likely packaged in polyvinyl chloride (PVC) wrapping film, while the highest DEHP levels were found in the vegetable and fruit samples.     

Determination of oxytetracycline residue in shrimp using a portable time-resolved analyzer and HPLC�CMS/MS validation

Oxytetracycline residue in shrimp muscle was determined using a portable time-resolved analyzer. After extraction in EDTA-metaphosphoric acid and filtration, the analyte was cleaned up using hydrophilic-lipophilic balance cartridges. Europium-sensitized luminescence (ESL) was measured at ??_ex = 385 nm and ??_em = 620 nm. Recoveries were 80.3 and 79.7% at 100 ng g^?1 and 2 ??g g^?1, respectively. The signal intensity was linear (r ² ?? 0.996) in each decade in the 5?C5,000 ng g^?1 range. Averaged relative standard deviation was ~2% and limit of detection was 8.3 ng g^?1. This instrument-method combination enabled sensitive in-situ quantification of OTC residue in shrimp. The ESL results were validated by HPLC?CMS/MS.     

Measurement of ampicillin residue levels in chicken eggs during and after medicated feed administration by LC-MS/MS

A simple and sensitive LC-MS/MS method was developed and validated for the determination of ampicillin (ABPC) in chicken eggs. Residues were extracted by reverse-phase solid-phase extraction. Chromatographic separation was performed using a reverse-phase column with an elution gradient. The limits of detection and quantification were 0.01 and 0.1 ng g^?1, respectively. For the 0.1–50 ng g^?1 concentration range, mean recovery and accuracy values were 93.9–98.5% and 100.2–118.0%, respectively. ABPC residue concentrations in eggs before, during and after 7 days of medicated feeding of maximum dosage (40 mg kg^?1 body weight day^?1) of ABPC were determined with the LC-MS/MS method. The maximum concentration of ABPC in eggs was 3.6 ± 1.7 ng g^?1 (mean ± SD) on the last day of the administration period. Residue concentrations of ABPC in eggs during and after ABPC administration were not over the Japanese maximum residue limit of 0.01 mg kg^?1.     

A survey of bisphenol A and other bisphenol analogues in foodstuffs from nine cities in China

Bisphenol A (BPA) is a high-production-volume chemical that is widely used in polycarbonate plastics and epoxy food-can coatings. Following several studies that have reported adverse effects of BPA over the past decade, other bisphenol analogues, such as bisphenol F (BPF), bisphenol S (BPS), bisphenol AF (BPAF), and bisphenol B (BPB), have been gradually developed as substitutes for BPA in several applications. Nevertheless, few studies have reported on the occurrence of compounds other than BPA in foodstuffs. In this study, 289 food samples (13 categories: cereals and cereal products, meat and meat products, fish and seafood, eggs, milk and milk products, bean products, fruits, vegetables, cookies/snacks, beverages, cooking oils, condiments, and others), collected from nine cities in China, were analysed for eight bisphenol analogues using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). BPA and BPF were found widely in foodstuffs at concentrations ranging from below the limit of quantitation (LOQ) to 299 ng g^–1 (mean = 4.94 ng g^–1) and from below the LOQ to 623 ng g^–1 (mean = 2.50 ng g^–1), fresh weight, respectively. The highest total concentrations of bisphenols (∑BPs: sum of eight bisphenols) were found in the category of vegetables that included canned products (mean = 27.0 ng g^–1), followed by fish and seafood (16.5 ng g^–1) and beverages (15.6 ng g^–1). ∑BP concentrations (mean = 2–3 ng g^–1) in milk and milk products, cooking oils, and eggs were low. Food samples sold in metallic cans contained higher mean ∑BP concentrations (56.9 ng g^–1) in comparison with those packaged in glass (0.43 ng g^–1), paper (11.9 ng g^–1), or plastic (6.40 ng g^–1). The daily dietary intakes of bisphenols were estimated, based on the mean concentrations measured and daily consumption rates of foods, to be 646 and 664 ng kg^–1 bw day^–1 for men and women, respectively.     

Determination of Ochratoxin A in Cereals and Feeds by Ultra-performance Liquid Chromatography Coupled to Tandem Mass Spectrometry with Immunoaffinity Column Clean-up

This paper describes the preparation of reusable immunoaffinity columns and the development of an ultra-performance liquid chromatography tandem mass spectrometry method combined with immunoaffinity column clean-up (IAC-UPLC-MS/MS) for the determination of ochratoxin A (OTA) in cereals and feeds. The monoclonal antibody (mAb) was produced from a stable hybridoma cell line (4H10), which belongs to the immunoglobulin G1 (κ-light chain) isotype. A competitive indirect enzyme-linked immunosorbent assay was used to characterize the mAb. The concentrations causing 50 % inhibition of binding of mAb to OTA-ovalbumin by free OTA, ochratoxin B, and ochratoxin C were 1.29, 4.78, and 0.94 ng mL^?1, respectively. The IAC-UPLC-MS/MS method offers a limit of quantification (LOQ, S/N >10) ranging from 0.5 to 1.0 μg kg^?1 and a limit of detection (LOD, S/N >3) ranging from 0.2 to 0.3 μg kg^?1 in cereal and feed samples. The IAC-UPLC-MS/MS method offers a good LOQ and LOD for OTA in cereal and feed samples. The accuracy and precision at this level fall within the EU regulatory limit. This methodology has been validated in four different matrices (millet, maize, soybean, and swine finisher diet) with highly satisfactory results and applied to the analysis of samples collected from the markets.     

Raman Spectroscopic and Mass Spectrometric Determination of Aflatoxins

This paper reported on selective Raman spectroscopic and mass spectrometric determination of functionalized aflatoxins. Performance parameter methods encompassed six component mixtures of AFs, B₁, G₁, M₁ and B_2A, G_2A, and M_2A at concentration range of ∈ 0.09₆–21.58₁?ng g^?1. Limits of detection (LODs) and limits of quantitation (LOQ) are 0.13₅ and 0.45 ng g^?1, respectively. The matrix effect of AFB_2A, AFG_2A, and AFM_2A in multicomponent mixtures is evaluated. The LODs of 0.11–0.09 ng g^?1 is achieved. Raman spectroscopic method performance parameters at concentration range of ∈ 0.10–5,000 μg kg^?1 for six component mixtures (r ²?=?0.9765₁) are LOD?=?10.13 μg kg^?1 and LOQ?=?33.7₆?μg kg^?1. The designed experimental schedule and sampling model is tested on contaminated grain samples. As far as the biochemistry and genetic engineering of aflatoxins and their major metabolites involved the high regioselectivity and binding affinity to N7 guanine residue at DNA, causing carcinogenic and mutagenic effects, the data reported are of emergency on the frontier fields of analytical chemistry, environmental bioengineering, monitoring, and assessment of human health risk from aflatoxins contamination. Aflatoxins are considered as biochemical weapons. Therefore, the essence of the study is on the instrumental methodology, which would be of interest and encompassed public security research and related scientific elaborations of more effective methods for (1) prevention, (2) reducing of the damages, and/or (3) acquisition of the outgrowths from biological (chemical) terrorist attacks.     

Simultaneous immunochemical detection of four banned antibiotic growth promoters in raw and cooked poultry tissue

Spiramycin, tylosin, bacitracin and virginiamycin are among a group of antibiotic growth promoters that have been banned in the European Union since the 1999 Council. This was due to concerns over the development of resistant bacteria emerging between humans and animals with the threat of antibiotics no longer being able to be used effectively to treat human infections. A sensitive and fast immunochemical method is presented for the determination of these four antibiotic growth promoters simultaneously in poultry tissue. The method employs methanol extraction followed by sample clean-up by solid-phase extraction (SPE) with determination by enzyme-linked immunoabsorbant assay (ELISA). The limit of detection (LOD) was less than 1 ng g^?1 and the detection capability (CCβ) was 3 ng g^?1 or less for all four antibiotic growth promoters. Validation was completed with both raw and cooked chicken, therefore either matrix could be used for the monitoring of these banned drugs. In a feeding trial no residues of either bacitracin or virginiamycin were found in medicated birds even without a withdrawal period. In the case of tylosin and spiramycin much higher residues level were detected immunochemically than was the case by mass spectrometry.     

Optimization of Matrix Solid-Phase Dispersion Method for Extraction of Aflatoxins from Cornmeal

An extraction method for simultaneous determination of aflatoxins (AFLAs) G2, G1, B2, and B1 in cornmeal, based on vortex-assisted matrix solid-phase dispersion (MSPD) and high-performance liquid chromatography (HPLC) with fluorescence detection was optimized by a central composite design, validated and applied. Multivariate analysis was performed to evaluate the effect of cornmeal composition on AFLA extraction. The amount and proportion of solid support (celite and C18) and volume of elution solvent (methanol and acetonitrile) were the variables tested. The mobile phase of methanol/acetonitrile/water (24:14:62, v/v/v) in isocratic elution mode provided satisfactory AFLA separation. The best recoveries (85.7 to 114.8%) were obtained when the sample preparation contained 25 mg C18 as solid support and 10 mL of elution solvent. The limits of detection ranged from 0.01 to 0.04 ng g^?1, and the limits of quantification varied from 0.02 to 0.1 ng g^?1. The optimized method was suitable for coarse and medium grind cornmeal. Multivariate correlation analysis showed that the main interferers for AFLA recovery were proteins and sugars.     

Vortex-Assisted Liquid–Liquid Microextraction Combined with HPLC for the Simultaneous Determination of Five Phthalate Esters in Liquor Samples

A vortex-assisted liquid–liquid microextraction (VALLME) method using hexanoic acid as extractant followed by high-performance liquid chromatography–diode array detection was developed for the extraction and determination of five phthalate esters (PAEs) including bis-methylglycol ester (DMEP), benzyl butyl phthalate (BBP), dicyclohexyl phthalate (DCHP), di-n-butyl phthalate (DBP), and di-n-octyl phthalate (DNOP) from liquor samples. In this method, hexanoic acid was employed as extraction solvent, because its density is lower than water. And vortex mixing was utilized as a mild emulsification procedure to reduce emulsification time and improve the effect of extraction. Under the studied conditions, five phthalate esters were successfully separated within 20 min and the limits of detection were 2.3 ng mL^?1 for DMEP, 1.1 ng mL^?1 for BBP, 1.9 ng mL^?1 for DCHP, 1.2 ng mL^?1 for DBP, and 1.5 ng mL^?1 for DNOP, respectively. Recoveries of the PAEs spiked into liquor samples were ranged from 89 to 93 %. The precisions of the proposed method were varied from 1.6 to 2.6 % (RSD). The VALLME method has been proved to have the potential to be applied to the preconcentration of the target analytes. Moreover, the method is simple, high sensitivity, consumes much less solvent than traditional methods and environmental friendly.     

Optimization of Headspace Single-Drop Microextraction Coupled with Gas Chromatography–Mass Spectrometry for Determining Volatile Oxidation Compounds in Mayonnaise by Response Surface Methodology

In this assay, headspace single-drop microextraction (HS-SDME) coupled with gas chromatography–mass spectrometry (GC–MS) as a simple, low-cost and rapid method has been developed and validated for determining volatile oxidation compounds including hexanal and heptanal in mayonnaise. The main microextraction variables affecting the HS-SDME procedure such as extraction temperature and time, stirring rate, and amount of NaCl were optimized by response surface methodology employing a central composite design. Obtained results demonstrated that higher yield of extracted analytes could be achieved under the following optimal conditions: extraction temperature of 45 °C, extraction time of 16 min, stirring rate at 700 rpm, and addition of 2 g NaCl. The optimized HS-SDME/GC–MS method was validated for oxidized mayonnaise samples (50 °C/48 h) by calculating analytical parameters (linearity, precision, accuracy, and sensitivity). Good linearity (R ²?>?0.99) was observed by plotting calibration curves of extracted hexanal and heptanal over the concentration range of 0.025–10 μg g^?1, and the repeatability of the method, expressed as relative standard deviation, were found to be 4.04 % for hexanal and 3.68 % for heptanal (n?=?7). After the microextraction process of spiked mayonnaise sample, high levels of relative recovery were obtained for hexanal (107.33 %) and heptanal (91.43 %). The detection limits were 0.008 ng g^?1 and 0.021 ng g^?1 for hexanal and heptanal, respectively, while quantification limits of hexanal and heptanal were calculated to be 0.027 ng g^?1 and 0.071 ng g^?1, respectively. The possibility of the HS-SDME followed GC–MS to determine and quantify volatile oxidation compounds such as hexanal and heptanal was confirmed by analyzing commercial fresh mayonnaise stored at 4 and 25 °C during 3 months.     

A New Extraction Method for the Determination of Oxytocin in Milk by Enzyme Immune Assay or High-Performance Liquid Chromatography: Validation by Liquid Chromatography–Mass Spectrometry

There has been a controversy regarding the use of exogenous oxytocin (OT) in milking cattle which may have toxicological consequences during nonphysiological exposure. In the present study, a new sensitive extraction method for OT was developed followed by enzyme immune assay (EIA) or high-performance liquid chromatography (HPLC) analysis. The extraction of OT in milk involves two steps: (1) TCA precipitation of milk proteins and (2) solid-phase extraction (SPE) cleanup process. Without these steps, analysis of OT in milk was not possible. Utilizing EIA as a quantitative tool the limit of detection (LOD) and limit of quantitation (LOQ) were found to be 7.74 and 10.3 pg?ml^?1, precision in terms of intra- and interday coefficient of variation was below 13 % (%RSD, N?=?8), while percent recoveries were between 85 and 92 %. Utilizing UV-HPLC, the LOD, LOQ, precision, and recovery values were found to be 4.1 ng?ml^?1, 9.8 ng?ml^?1, 2–10 %, and 84–91 %, respectively. OT was found to be stable against adverse temperature (up to 100 °C) and pH (2 to 10) and simulated gastric fluid digestibility assay. Four milk samples collected from the market were analyzed, which showed that TCA precipitation and SPE steps are mandatory and the results were validated by LC-MS showing mass ion peak at 1 kD.     

Moniliformin analysis in maize samples from North-West Italy using multifunctional clean-up columns and the LC-MS/MS detection method

A fast clean-up method has been developed to purify maize extracts and to detect moniliformin (MON) in maize samples from North-West Italy over a four-year period (2008–2011). The method is based on the use of MycoSep® 240 Mon clean-up columns (Romer Labs^®). Samples were extracted using acetonitrile/water (84:16, v/v), and the extracts were purified with previously described clean-up columns. The liquid chromatography–tandem mass spectrography (LC-MS/MS) analysis has been carried out by means of hydrophilic interaction chromatography (HILIC), combined with negative electrospray mass spectrometry. The method has a recovery of 76–91% (relative standard deviation, RSD%: 6–14%), a limit of detection (LOD) of 1 µg kg^–1 and a limit of quantification (LOQ) of 4 µg kg^?1. Naturally contaminated maize (108 samples) was analysed for MON content. The average percentages of positive samples was 93% with the following ranges (µg kg^?1): 33–2606 (2008); <LOD–527 (2009); <LOD–920 (2010); <LOD–409 (2011).     

Are Chileans exposed to dietary furan?

Chilean consumer preferences include foods that may contain considerable amounts of furan, a potential human carcinogen. However, there is no information regarding dietary exposure to furan in Chile. Thus, the objective of this work was to determine the Chilean exposure to dietary furan. To accomplish this objective, the furan concentration of 14 types of commercial foods processed at high temperature were analysed based on a modified headspace-GC/MS (HS-GC/MS) method in which the limits of detection for different food matrices ranged from 0.01 to 0.6 ng g^?1. In addition, a risk assessment was made with exposure estimates based on dietary data from national studies on different age groups (9-month-old babies, school children, adults and elderly people). Of the food items surveyed “American”-type coffee (espresso coffee plus hot water) obtained from automatic coffee machine (936 ng g^?1) and low moisture starchy products like crisps and “soda”-type crackers showed the highest furan concentrations (259 and 91 ng g^?1, respectively). Furthermore, furan was also found in samples of breakfast cereals (approximately 20 ng g^?1), jarred fruit baby foods (8.5 ng g^?1) and orange juice (7.0 ng g^?1). School children (aged 9–13 years) represented the highest intake of furan (about 500 ng kg^?1_bw day^?1), with margins of exposure of 2479 and 2411, respectively, which points to a possible public health risk.     

Polycyclic aromatic hydrocarbons in cereal products on the Turkish market

The contamination level of four EU marker polycyclic aromatic hydrocarbons (PAHs) in some cereal-derived products was surveyed in this study. Thirty-eight samples, 20 bread and 18 breakfast cereals, were purchased from retail shops and local markets of East Black sea region in Turkey. The samples were analysed for four EU marker PAHs, using ultrasonic extraction, solid-phase extraction (SPE) clean up and stable-isotope dilution gas chromatography with mass-spectrometric (GC/MS) detection. The method was validated with the parameters linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ) and uncertainty. Total content of the four PAHs in bread varied from 0.19 to 0.46 µg kg^?1 and in breakfast cereals from 0.10 to 0.87 µg kg^?1.     

Development and validation of an LC-MS/MS method for the simultaneous analysis of 28 specific narcotic adulterants used in dietary supplements

The purpose of this study was to develop a method to analyse the concentration of multiple illegal narcotics present in dietary supplements. To this end, we established and optimised a procedure using LC-MS/MS simultaneously to analyse 28 narcotic compounds in various forms of dietary supplements, including powders, tablets, liquids and capsules. In addition, candy and cookies that have also had detected cases of adulteration were also analysed. The specificity, linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ), stability and recovery for these methods were validated accordingly. The LOD and LOQ of the LC-MS/MS ranged from 0.01–50.0 to 0.03–100 ng g^?1, respectively. The linearity of these results was good (r² > 0.99), with intra- and inter-day precision values of 0.2–5.2% and 0.2–4.8%, respectively. Further, the intra- and inter-day accuracies of this method were 97.0–103.4% and 94.6–103.1%, respectively. The stability RSD was less than 7.8%. The mean recovery for this LC-MS/MS procedure was 81.1–117.4%, with an RSD less than 9.8%. Following the validation of our method, we analysed 47 commercially available dietary supplements obtained in Korea. Whilst none of these samples had detectable amounts of the 28 specified narcotic adulterants, our novel LC-MS/MS procedure can be utilised comprehensively and continually to monitor illegal drug adulteration in various forms of dietary supplements.     

Analytical method for fast screening and confirmation of multi-class veterinary drug residues in fish and shrimp by LC-MS/MS

A multi-class, multi-residue analytical method based on LC-MS/MS detection was developed for the screening and confirmation of 28 veterinary drug and metabolite residues in flatfish, shrimp and eel. The chosen veterinary drugs are prohibited or unauthorised compounds in Korea, which were categorised into various chemical classes including nitroimidazoles, benzimidazoles, sulfones, quinolones, macrolides, phenothiazines, pyrethroids and others. To achieve fast and simultaneous extraction of various analytes, a simple and generic liquid extraction procedure using EDTA-ammonium acetate buffer and acetonitrile, without further clean-up steps, was applied to sample preparation. The final extracts were analysed by ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). The method was validated for each compound in each matrix at three different concentrations (5, 10 and 20 ng g^–1) in accordance with Codex guidelines (CAC/GL 71-2009). For most compounds, the recoveries were in the range of 60–110%, and precision, expressed as the relative standard deviation (RSD), was in the range of 5–15%. The detection capabilities (CCβs) were below or equal to 5 ng g^–1, which indicates that the developed method is sufficient to detect illegal fishery products containing the target compounds above the residue limit (10 ng g^–1) of the new regulatory system (Positive List System – PLS).     

Determination of Chlorothalonil Residue in Cabbage by a Modified QuEChERS-Based Extraction and Gas Chromatography–Mass Spectrometry

Being susceptible to any matrix with pH >5, taking cabbage as an example, the low recovery of chlorothalonil residues adsorbed onto the cabbage matrix was almost completely improved by extracting with 1/1 (v/v) acetonitrile (containing 5 % acetic acid)/toluene. Under the optimized conditions, the recoveries of chlorothalonil in cabbage fortified at three concentrations of 0.5 to 10 mg kg^?1 were 71–93 % with relative standard deviations (RSDs) lower than 6 %. The limit of detection (LOD) and the limit of quantification (LOQ) of the gas chromatography–mass spectrometry (GC–MS) method for chlorothalonil were 0.05 and 0.5 mg kg^?1, respectively, which were much lower than the maximum residue limits (MRLs). The proposed analytical method demonstrated a potential for its application to monitor for chlorothalonil and to help assure food safety, especially base-sensitive-pesticide analysis.