Food Analytical Methods

Quantitation of Selenomethionine in Multivitamins and Selenium Supplements by High Performance Liquid Chromatography Inductively-Coupled Plasma Mass Spectrometry Abstract VITA-1 and VITB-1 multivitamin and mineral supplement candidate reference materials from the National Research Council Canada were analyzed for their total selenium and selenomethionine contents. Following a methanesulfonic acid reflux to extract selenomethionine from the selenized yeast in the multivitamins, analysis by high-performance liquid chromatography-inductively coupled plasma triple quadrupole mass spectrometry resulted in concentrations of 7.4 ± 3.0 μg SeMet g–1 and 16.4 ± 6.5 μg SeMet g−1 in VITA-1 and VITB-1, respectively. Twelve commercially available multivitamins and selenium supplements were analyzed following the same protocol. Seven of these were noted to contain 85–115% of the selenium stated on the label; the others ranged from 5 to 147% of the claimed amount. Only one multivitamin contained selenomethionine at a concentration above the detection limit, but the amount found in the selenium supplements matched the label claims within a reasonable level of uncertainty. For comparison, two certified reference materials—wheat gluten and egg powder, both certified for total selenium only—were also examined and it was determined that selenomethionine accounted for 58% and 25% of the selenium in these food products, respectively.

Development of a Sensitive Monoclonal Antibody–Based Indirect Competitive Enzyme-Linked Immunosorbent Assay for the Determination of Monensin in Edible Chicken Tissues Abstract To monitor monensin (MON) residues in chicken tissues, a monoclonal antibody (mAb)–based indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed in this study. The haptenMON was obtained by adding hydrochloric acid to a MON salt, and then was coupled with carrier protein. After the inoculation of female Balb/c mice and cell fusions, one cell line, MON/4C9, was obtained. The MON/4C9 antibody exhibited the ability to specifically recognize MON with IC50 1.28 μg L−1.Based on this mAb, an optimized ic-ELISA protocol was performed using only methanol-water (8:2, v/v) in chicken tissue samples. The limits of detection and the limits of quantification of MON in various sample matrices varied from 0.38 to 1.01 μg kg−1. The recoveries ranged from 71.9 to 116.9% in chicken tissues, and the intra- and inter-assay CVs were all less than 18%. Moreover, the developed method also exhibited a positive correlation with the results of HPLC-MS conducted on the samples. These results suggest that the prepared mAb and the developed ic-ELISA method will be a useful tool for detecting MON in chicken tissues.

Aflatoxin B 1 Determination in Peanuts by Magnetic Nanoparticle–Based Immunofluorescence Assay Abstract A sensitive immunofluorescence assay for rapid AFB1 determination was developed. Polyclonal anti-AFB1 antibody was immobilized onto magnetic nanoparticles (MNPs). The optimal amount of immobilized antibody was found—40 μg antibody per 1 mg MNPs. The conjugate of AFB1 with bovine serum albumin (BSA) and fluorescein isothiocyanate was prepared. UV-Vis and fluorescence spectrophotometric analyses of the obtained conjugate proved the successful conjugate formation. Optimal amount of MNPs with immobilized antibody (0.25 mg) and the optimal concentration of fluorescent conjugate of AFB1 (28 μg/mL) were established. A competitive assay of AFB1 was performed. The toxin solubility and stability were optimal for the assay when using buffer solution with 10% methanol. It was found that the sensitivity of the developed AFB1 assay was significantly higher with 0.1% BSA stabilizing AFB1 solutions. The linear range of the proposed method was 2–100 pg/mL. The immunoassay was applied for determination of AFB1 in spiked peanuts.

Simultaneous Determination of Isofetamid and Its Two Metabolites in Fruits and Vegetables Using Ultra-Performance Liquid Chromatography with Tandem Mass Spectrometry Abstract In this paper, an efficient analytical method for the simultaneous determination of a new fungicide (isofetamid) and its two metabolites in fruits and vegetables was developed using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) pretreatment method and ultra-performance liquid chromatography-tandem mass spectrometry. The three compounds were extracted with acetonitrile and cleaned up using primary secondary amine, octadecylsilane, and graphitized carbon black. The three analytes were well separated with good specificity using an electrospray ionization source in positive mode within 5.0 min. The mean recoveries in apple, strawberry, grape, tomato, cucumber, and lettuce for the three target compounds at different levels ranged from 74 to 107%, with relative standard deviations lower than 12.3%. The method showed excellent linearity (R2 ≥ 0.9946) for the three compounds. The limits of quantification of isofetamid and its metabolites were 1 μg kg−1 in apple, tomato, and cucumber and 100 μg kg−1 in strawberry, grape, and lettuce. The proposed method was successfully applied to a residue dynamic experiment, and it can be considered a strong alternative method to monitor the residues of isofetamid and its metabolites simultaneously in fruits and vegetables.

Fast Sequential Determination of Zn, Fe, Mg, Ca, Na, and K in Infant Formulas by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry Using Ultrasound-Assisted Extraction Abstract In this work, an analytical procedure based on ultrasound-assisted extraction (UAE) was developed for the fast sequential determination of six elements (Zn, Fe, Mg, Ca, Na, and K) in infant formulas using high-resolution continuum source flame atomic absorption spectrometry (HR-CS F AAS). The analytes extraction was performed using HNO3 2.1 mol L−1 and 10 min of sonication time at 80 °C. The limits of detection obtained were 12, 13, 0.48, 96, 137, and 14 mg kg−1 for Zn, Fe, Mg, Ca, Na, and K, respectively. The analysis of a certified reference material of non-fat milk powder (SRM 1549) and infant formula samples after microwave digestion confirmed the trueness of the developed method. Thus, the UAE procedure was employed in order to determine these six elements and their concentration in six infant formulas and their content (in mg kg−1) ranged between 64 and 431 for Zn, 64–370 for Fe, 420–2421 for Mg, 1145–8547 for Na, 750–14,491 for K, and 2827–11,340 for Ca.

Front-Face Fluorescence Combined with Second-Order Multiway Classification, Based on Polyphenol and Chlorophyll Compounds, for Virgin Olive Oil Monitoring Under Different Photo- and Thermal-Oxidation Procedures Abstract Room temperature excitation-emission matrices (EEMs), recorded using front-face fluorescence spectroscopy, and combined with second-order multiway classification methods, were explored as potential tools for controlling the storage conditions of extra virgin olive oil samples (EVOO). Factors such as UV-irradiation, sunlight exposition and temperature up to 80 °C were studied. For each sample, EEMs were obtained in two spectral regions, corresponding to polyphenols, and chlorophyll and derivatives, respectively. The full fluorescence information of excitation-emission matrices was processed with parallel factor analysis (PARAFAC) and PARAFAC supervised by linear discriminant analysis (LDA). The models allowed the discrimination between non-irradiated and irradiated EVOO samples, in both spectral regions. With a temperature of 80 °C, and a heating time of 30 min, the formation of secondary oxidation products was appreciable. In these conditions, the first component of PARAFAC showed a remarkable modification in its profile and LDA-PARAFAC allowed the discrimination between non-heated and heated EVOO samples.

Magnetic Graphene Solid-Phase Extraction for the Determination of 47 Kinds of Non-steroidal Anti-inflammatory Drug Residues in Animal Food with Liquid Chromatography Tandem Mass Spectrometry Abstract Based on magnetic graphene (Fe3O4-G), a liquid chromatography with tandem mass spectrometric detection (LC-MS/MS) method coupled with magnetic solid-phase extraction was developed for the simultaneous detection of 47 kinds of nonsteroidal anti-inflammatory drug (NSAID) residues in meat of swine, chicken, and bovine. The samples were extracted with acetonitrile-phosphate, then the extracts were purified by dispersed solid-phase extraction based on magnetic graphene (Fe3O4-G). The linearity range is 0.1–50 μg L−1. Limits of detection were between 0.1 μg kg−1 and 0.5 μg kg−1, and limits of quantification were between 0.5 μg kg−1 and 1.0 μg kg−1. The average recoveries were 72.4–97.1% at spiking levels. The inter-day RSDs varied from 5.3 to 12.6%. Due to the advantages of easy collection of magnetic solid-phase extraction materials, the method was more rapid and efficient for the enrichment and separation without filling columns. The sensitivity, precision, and accuracy method was suitable for simultaneous detection of multi-component residues of nonsteroidal anti-inflammatory drugs.

Magnetically Modified Porous β-Cyclodextrin Polymers for Dispersive Solid-Phase Extraction High-Performance Liquid Chromatography Analysis of Sudan Dyes Abstract Two types of magnetically modified porous β-cyclodextrin polymers (PCDPs) were successfully synthesized. The first type, named MPCDPs(C), was fabricated by co-precipitating PCDPs with Fe3O4, resulting in a Brunauer–Emmett–Teller (BET) surface area of 106.68 m2 g−1. The second type, named MPCDPs(M), was fabricated by grafting PCDPs onto the surface of magnetic microspheres, resulting in a BET surface area of 34.63 m2 g−1. Both MPCDPs were found to enable effective extraction and separation of Sudan dyes from foodstuffs and environmental water. Coupled with high-performance liquid chromatography, the limits of detection for Sudan dyes were in the range of 0.013–0.054 ng mL−1 with MPCDPs(C), and 0.028–0.039 ng mL−1 with MPCDPs(M). Recoveries were between 85.8 and 102.8% for spiked food samples and 88.3 and 103.2% for spiked water samples, suggesting that the developed methods are promising for accurate quantification of Sudan dyes at trace levels in foodstuffs and environmental water.

Isotope Dilution LC-MS/MS Method for Glycine Betaine in Manila Clam ( Tapes philippinarum ) Abstract Glycine betaine (GB) is a natural compound with demonstrated metabolic functions in mammals and beneficial effects on the human body: it protects cells under osmotic stress, as an organic osmolyte, and acts as a methylating agent in several vital biochemical pathways. The main dietary sources of GB are vegetables, such as cereals, spinach, chard and beetroot, above all; shellfish is one of the richest animal sources. A simple method for the quantification of GB in the edible portion of Manila clams (Tapes philippinarum) was setup, using ultra-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Isotope-labelled internal standards were used during sample extraction, in order to ensure an accurate quantification. The method was successfully validated following the Commission Decision 657/2002/EC as a guideline; since GB is an endogenous compound, present in very high concentrations in the target matrix, appropriate adjustments were taken. The method developed reported very satisfying performances in terms of linearity, trueness and precision; moreover, its applicability was demonstrated on commercial pools of Manila clams.

Optimization of Ultrasound-Assisted Extraction of Anthocyanins and Phenolic Compounds from Black Soybeans ( Glycine max L.) Abstract Black soybeans have been reported to contain high antioxidant content, including anthocyanins. Ultrasound-assisted water extraction of antioxidants from Korean black soybeans (Glycine max [L.] Merr. Cheongja4ho) was investigated for the first time. A three-level, three-factor Box-Behnken design using a response surface methodology (RSM) was employed to optimize the conditions for the maximum yields of three dependent variables, including total anthocyanin content, total phenol content, and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, based on 17 different experiments. The solid-liquid ratio (X1, 1/30–1/50 g mL−1), extraction time (X2, 1–9 min), and amplitude (X3, 20–100%) significantly affected three dependent variables. The optimized conditions were solid-liquid ratio of 49.1 g mL−1, extraction time of 8.59 min, and amplitude of 81.4%. At the optimum point, the total anthocyanin content, total phenol content, and ABTS•+ scavenging activity were 66.44, 940.96, and 242.45 mg 100 g−1. The difference (%) between the predicted and experimental values was less than 6.40%, indicating that the model fits well. The conditions optimized for ultrasound-assisted water extraction of antioxidants from black soybeans can be applied as an efficient technique for extracting anthocyanins in plants on a larger scale.

Alexandros Sfakianakis
Anapafseos 5 . Agios Nikolaos
Crete.Greece.72100
2841026182

6948891480

alsfakia@gmail.com