bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiwavelength Spectral Correction for the Simultaneous Determination of Cu(II), Fe(II), and Zn(II) with 1-(5-Bromo-2-Pyridylazo)-2-Naphthol-6-Sulfonic Acid
Authors: Gao Hong-Wen
Published: February 2020

A new analytical method is described for the simultaneous determination of various components by multiwavelength spectrophotometry. Because of the influence of the free ligand and various complexes on spectrophotometric absorption, the spectral correction principle was used to establish the calculation matrix formula. The 3 sensitive reactions of Cu(II), Fe(II), and Zn(II), with 1-(5-bromo-2-pyridylazo)-2-naphthol-6-sulfonic acid were studied at pH 10.5. In analyses of fortified samples, the recoveries of Fe, Zn, and Cu were between 93.0 and 103%, 87.0 and 108%, and 92.5 and 108%, respectively; the relative standard deviations for 5 determinations of Fe, Zn, and Cu in unfortified ore were 3.6, 5.8, and 4.5%, respectively.
Determination of Sulfate in Natural and Residual Waters by Turbidimetric Flow-Injection Analysis
Authors: Morais Inês P A , Rangel António O S S , Souto M Renata S
Published: February 2020

A turbidimetric flow-injection system was developed for the determination of sulfate in natural and residual water samples, with no previous treatment, using spectrophotometric detection. The precipitating agent, 7.0% (w/v) barium chloride solution prepared in 0.10% (w/v) polyvinyl alcohol, was added by using the merging-zones approach. A 100 mg/L sulfate solution in 0.07M nitric acid was mixed with the sample before it entered the injection loop to improve the detection limit, provide in-line pH adjustment, and prevent the interference of some anionic species. The relative standard deviations of the results were between 1.4 and 3.0% and were in agreement with results obtained by the reference method. Samples within a linear concentration range of 10–120 mg SO42−/L can be analyzed at a rate of 40/h. The detection limit is 5 mg SO42−/L.
Rappaport-Vassiliadis Medium for Recovery of Salmonellaspp. from Low Microbial Load Foods: Collaborative Study
Authors: Hammack Thomas S , Amaguaña R Miguel , Andrews Wallace H ,   Collaborators:, Al-Hasani S M , Asmundson R , Battista K , Beatty S J , Berges-Soubies V A , Bozicevich T , Brooks D , Case J , Coles C , Copeland F , Davis-Debella P E , Entis P , Feldsine P , Fourcade L , Garcia G R , Goins D G , Jackson T , Koch S , Lafogiannis J A , Lee J , Lerner I , McIntyre D , McKee B , McNally S , Muchnik V , Mui L , Pfundheller R , Raghubeer E V , Rains D , Ruscica G , Schmieg J , Sellers R , Smoot M , Sobol R , Thunberg R , Torres S , Trinidad L F , Tuncan E , Watson J M
Published: February 2020

Twenty-three laboratories participated in a collaborative study to compare the relative effectiveness of Rappaport-Vassiliadis (RV) medium incubated at 42°C, selenite cystine (SC) broth (35°C), and tetrathionate (TT) broth (35 and 43°C) for recovery of Salmonella from the following foods with a low microbial load: dried egg yolk, dry active yeast, ground black pepper, guar gum, and instant nonfat dry milk. For dry active yeast, lauryl tryptose (LT) broth, incubated at 35°C, was used instead of SC broth. All of the foods were artificially inoculated with single Salmonella serovars, that had been lyophilized before inoculation, at high and low target levels of 0.4 and 0.04 colony forming units/g food, respectively. For analysis of 870 test portions, representing all of the foods except yeast, 249 Salmonella-positive test portions were detected by RV medium, 265 by TT broth (43°C), 268 by TT broth (35°C), and 269 by SC broth (35°C). For analysis of 225 test portions of yeast, 79 Salmonella-positive test portions were detected by RV medium, 79 by TT broth (43°C), 84 by TT broth (35°C), and 68 by LT broth (35°C). RV medium was comparable to, or even more effective than, the other selective enrichments for recovery of Salmonella from all of the foods except guar gum. It is recommended that RV (42°C) and TT (35°C) be used with foods that have a low microbial load, except for guar gum for which SC (35°C) and TT (35°C) are recommended.
New Method for Determination of Ten Pesticides in Human Blood
Authors: GarcÍa-Repetto Rosario , Giménez M Paz , Repetto Manuel
Published: February 2020

An analytical method was developed for precise identification and quantitation of 10 pesticides in human blood. The pesticides studied, which have appeared frequently in actual cases, were endosulfan, lindane, parathion, ethyl-azinphos, diazinon, malathion, alachlor, tetradifon, fenthion and dicofol (o-p′ and p-p′ isomers). The current method replaces an earlier method which involved liquid–liquid extraction with a mixture of n-hexane–benzene (1 + 1). The extraction is performed by solid-phase extraction, with C18 cartridges and 2 internal standards, perthane and triphenylphosphate. Eluates were analyzed by gas chromatography (GC) with nitrogen–phosphorus and electrochemical detectors. Results were confirmed by GC–mass spectrometry in the electron impact mode. Blood blank samples spiked with 2 standard mixtures and an internal standard were used for quantitation. Mean recoveries ranged from 71.83 to 97.10%. Detection and quantitation limits are reported for each pesticide. Examples are provided to show the application of the present method to actual samples.
Monitoring of Pesticide Residues in Egyptian Fruits and Vegetables During 1996
Authors: Dogheim Salwa M , Gad Alla Sohair A , El-Marsafy Ashraf M
Published: February 2020

Samples of the most common fruits and vegetables were collected from 8 local markets in 6 governorates. These 1579 samples were analyzed for residues of 53 pesticides, which included organophosphorus and organonitrogen compounds and some synthetic pyrethroids. Samples were also analyzed for residues of organochlorine pesticides, although they had been prohibited from use several years ago. Only 510 of the 1579 samples were analyzed for dithiocarbamate pesticide residues, which were determined as CS2. Overall, 76.1% of the total analyzed samples had no detectable residues, 23.9% contained detectable residues, and 2.59% contained residues that exceeded maximum residue limits. For individual crops, contaminated samples ranged from 0 to 96% of the number of samples analyzed. However, the highest violative percentage for samples of individual crops was 12.5. Chlorpyrifos, carbaryl, dimethoate, bromopropylate, and profenofos were the violative pesticides determined in fruit and vegetable samples. The results of the current study demonstrated that no restricted or banned pesticides such as DDT, HCH, and their isomers were found in any of the samples analyzed. Dithiocarbamate residues were detected in 9.4% of the 510 samples analyzed, with a violative percentage of 0.39, representing one grape sample and one peach sample.
Determination of Arsenic in Seafood by Focused Microwave Digestion and Hydride Generation–Atomic Fluorescence Detection
Authors: Vilanó Marc , Rubio Roser
Published: February 2020

A new method was developed for total arsenic determination in seafood products such as oysters, mussels, tuna fish, and algae. Matrix decomposition and oxidation to arsenate of all the arsenic compounds in the product were completed in 25 min by using a 3-step program of focused microwaves (40–120 W) with nitric and sulfuric acids. Quantitation was performed by hydride generation-atomic fluorescence detection (HG–AFS). Results of method optimization are presented and discussed. A detection limit <125 μg/kg arsenic was obtained; the quantitation limit was close to 400 μg/kg, with repeatability and reproducibility <5% relative standard deviation. Validation was performed by analyzing 4Reference Materials (arsenic concentration expressed as mg/kg): The National Institute of Standards and Technology SRM 1566a Oyster tissue (14.0 ± 1.2); the Bureau Community of Reference (now Standard Measurements & Testing Program) CRM 278 Mussel tissue (5.9 ± 0.2) and CRM 627 Tuna fish (4.8 ± 0.3); and the International Atomic Energy Agency RM 140 Fucus sample (44.3 ± 2.1).
Mixed-Mode Solid-Phase Extraction and Cleanup Procedures for the Liquid Chromatographic Determination of Thiabendazole and Carbendazim in Fruit Juices
Authors: Young Michael S , Phillips Dorothy J , Iraneta Pamela C , Krol Jim
Published: February 2020

Solid-phase extraction (SPE) procedures were developed for rapid cleanup and determination of thiabendazole and carbendazim in orange, apple, and grape juices. Samples were prepared by using an SPE cartridge containing a mixed-mode sorbent with both reversed-phase and strong cation-exchange chemistries. Analysis was by liquid chromatography with photodiode-array UV detection. Orange juice was analyzed by mixed-mode cation-exchange extraction with reversed-phase cleanup; the other juices were analyzed by reversed-phase extraction with cation-exchange cleanup. Recoveries >80% for carbendazim and >90% for thiabendazole. Quantitation limits were 20 μg/L for both analytes.
Simultaneous Determination of Residues of Emamectin and Its Metabolites, and Milbemectin, Ivermectin, and Abamectin in Crops by Liquid Chromatography with Fluorescence Detection
Authors: Yoshii Kimihiko , Kaihara Akiko , Tsumura Yukari , Ishimitsu Susumu , Tonogai Yasuhide
Published: February 2020

A liquid chromatographic (LC) method was developed for the determination of emamectin and its metabolites (8,9-Z-isomer, N-demethylated, N-formylated, and N-methylformylated emamectin) in various crops. The analytes were extracted with acetone, cleaned up on cartridge columns (C18 and NH2), derivatized with trifluoroacetic anhydride and 1-methylimidazole, and determined by LC with fluorescence detection. Because radish inhibited the formation of the fluorescent derivatives, an additional Bond Elut PRS cartridge was used in the cleanup of Japanese radish samples. During sample preparation, N-formylated emamectin partially degraded to emamectin B1b and emamectin B1a, and the 8,9-Z-isomer partially degraded to N-demethylated emamectin. Therefore, emamectin and its metabolites were determined as total emamectin, i.e., their sum was estimated as emamectin benzoate. Their recoveries from most crops were approximately 80–110% with the developed method. The detection limits for the analytes in vegetables were 0.1–0.3 parts per trillion (ppt). The results for these compounds were confirmed by LC/mass spectrometry (LC/MS; electrospray ionization mode). Because the fluorescent derivative of emamectin was undetectable by LC/MS, the results for the analyte were confirmed by using a sample solution without derivatization. Limits of detection by LC/MS were similar to the fluorescence detection limits, 0.1–0.3 ppt in vegetables. In addition to the emamectins, milbemectin, ivermectin, and abamectin were also determined by the developed method.
13C-IRIS: An Improved Method To Detect the Addition of Low Levels of C4-Derived Sugars to Juices
Authors: Day Martin P , Correia Patricia , Hammond David A
Published: February 2020

A method to improve the detection of cane or corn sugar addition to fruit juices has been developed. This involves the isolation of the individual sugars and measurement of their carbon isotope ratios. Using the Isotopic Relations of Individual Sugars approach, the additions of cane sucrose or cane invert as low as 4% of the total sugars can be detected in orange juice. This method offers a significant improvement over the conventional carbon isotopic method that has a detection limit of about 10%.
Isolation of Lipid and 2-Alkylcyclobutanones from Irradiated Foods by Supercritical Fluid Extraction
Authors: Stewart Eileen M , McRoberts W Colin , Hamilton John T G , Graham William D
Published: February 2020

The 2-alkylcyclobutanone method was adopted as a European Standard (EN1785) and MAFF Validated Method (MAFF V37) in 1996 for the detection of irradiated food containing fat. As the method requires a relatively long period (ca 2 days) of time for extraction of the 2-alkylcyclobutanones from a foodstuff, a means was sought to increase the speed at which these irradiation markers could be isolated while at the same time decreasing the amount of organic solvents required. Thus, the technique of supercritical fluid extraction (SFE) was investigated. Results showed that SFE can be used for the rapid extraction (60 min) of lipid from irradiated foods such as chicken, pork, liquid whole egg, ground beef, and from the seeds of irradiated mango and papaya with only 10 mL n-hexane being necessary for collection of the extracted sample. A method was also developed whereby the 2-alkylcyclobutanones can be selectively extracted from irradiated foods without prior extraction of the lipid. The sample extract, in 10 mL n-hexane, is purified through a Florisil SPE cartridge which is washed with 10 mL n-hexane and the 2-alkylcyclobutanones eluted with 10 mL 2% diethyl ether in n-hexane before analysis by gas chromatography/mass spectrometry. 2-Dodecylcyclobutanone and 2-tetradecylcyclobutanone were selectively extracted from irradiated chicken meat, liquid whole egg, ground beef, and mango as well as from beef burgers and baked products containing irradiated ground beef and liquid whole egg, respectively. Using this method, samples can be analyzed for irradiation treatment within 6 h as opposed to the 2-day period required for the EN1785/MAFF V37 validated method.
Comparison of Liquid Chromatography/Mass Spectrometry, ELISA, and Phosphatase Assay for the Determination of Microcystins in Blue-Green Algae Products
Authors: Lawrence James F , Niedzwiadek Barbara , Menard Cathie , Lau Benjamin P Y , Lewis David , Kuper-Goodman Tine , Carbone Susan , Holmes Charles
Published: February 2020

More than 100 samples of blue-green algae products (consisting of Aphanizomenon, Spirulina, and unidentified blue-green algae) in the form of pills, capsules, and powders were collected from retail outlets from across Canada. The samples were extracted with 75% methanol in water and centrifuged to remove solids. Aliquots of the extracts along with spiked blank sample extracts were sent to each participating laboratory and independently analyzed for microcystins by enzyme-linked immunosorbent assay (ELISA), protein phosphatase inhibition assay, and by liquid chromatography–tandem mass spectrometry (LC–MS/MS) after sample cleanup using C18 solid–phase extraction. The results obtained by ELISA and LC–MS/MS agreed very well over a concentration range of about 0.5–35 μg/g. The colorimetric phosphatase results generally agreed with the other 2 methods. While the 2 biochemical assays measured total microcystin content compared with a standard of microcystin LR, the LC–MS/MS method measured specific microcystins (LA, LR, RR, YR) using external standards of these for identification and quantitation. Microcystin LR was found in all positive samples by LC–MS/MS. Microcystin LA was the only other microcystin found in the samples analyzed. These 2 microcystins represent essentially all the microcystins that were present in the extracts. Otherwise, the LC–MS/MS results would have been significantly lower than the results of the biochemical assays had other unknown microcystins been present.
Rapid Determination of Total trans Fat Content—An Attenuated Total Reflection Infrared Spectroscopy International Collaborative Study
Authors: Mossoba Magdi M , Adam Michael , Lee Theresa ,   Collaborators:, Bastyr J , Bhat S N , Dawson T , Guldan M , Hansen S , Hayes C , Lambert E S , Lee T , Mossoba M M , Reh C , Sedman J , Smith G , van Schaick M A , van Velzen E J J
Published: February 2020

Interest in trans fat labeling has prompted efforts to develop new, more efficient methods for rapidly and accurately determining trans fat content of foods. A novel and rapid (5 min) attenuated total reflection–Fourier transform infrared (ATR–FTIR) spectroscopic procedure was recently developed and applied to food products. This procedure was voted official method AOCS Cd 14d-99 by the American Oil Chemists' Society in 1999 after testing in a 12 laboratory international collaborative study. The results of the study are described in this paper. Analytical ATR–FTIR results exhibited high accuracy in the range 5–40% trans; results tended to have <2% high bias relative to the gravimetrically determined values. The precision of this internal reflection method was found to be superior to the precision of transmission infrared official methods. It is recommended that the applicability of the ATR–FTIR method be limited to trans levels of >5% (as percent of total fat).
Multiresidue Determination of Pesticides in Honey by Matrix Solid-Phase Dispersion and Gas Chromatography with Electron-Capture Detection
Authors: Albero Beatriz , Sánchez-Brunete Consuelo , Tadeo José L
Published: February 2020

A multiresidue method was developed for the determination of 15 pesticides (organochlorines, organophosphorus compounds, pyrethroids, and other acaricides) in various commercial honeys (eucalyptus, lavender, orange, rosemary, and multifloral). The analytical procedure is based on the matrix solid-phase dispersion of honey in a mixture of Florisil and anhydrous sodium sulfate; the mixture is placed in small plastic columns and extracted with hexane–ethyl acetate (90 + 10, v/v). The pesticide residues are determined by capillary gas chromatography with electron-capture detection. Recoveries with the method at concentrations between 0.15 and 1.5 μg/g ranged from 80 to 113%, and relative standard deviations were <10% for all the pesticides studied. The pesticide detection limits were within the range 0.5–5 mg/kg for organochlorines, around 3 μg/kg for the chlorinated organophosphorus pesticides studied, near 15 μg/kg for fluvalinate, and about 3 μg/kg for the other pyrethroids.
Fluorophotometric Thin-Layer Chromatography of Ginkgo Terpenes by Postchromatographic Thermochemical Derivatization and Quality Survey of Commercial Ginkgo Products
Authors: Peishan Xie , Yuzhen Yan , Haoquan Qian , Qiaoling Lin
Published: February 2020

Terpenoid lactones in Ginkgo biloba leaves are the main active constituents and the content of these terpenes is therefore the key factor for evaluating the quality of the leaves, the extract, and its preparations distributed on the market. The precleanup sample solutions were applied onto the silica gel plate modified with sodium acetate solution and developed with a solvent system of toluene–ethyl acetate–acetone–methanol, and a fluorescence chromatogram was generated by means of postchromatographic thermal chemical reaction. Fluorescence scanning was conducted quantitatively. The methodology validation confirmed that it is a practical alternative for routine quality control for ginkgo terpenes and the results are comparable with those obtained by high-performance liquid chromatography (HPLC). On the basis of the method established, a quality survey of the various commercial ginkgo products from different sources was undertaken. The obtained data demonstrated that the fluctuation of the content of individual terpene and/or the total terpenes among replicate samples is so significant as to cast doubts on the consistency of their pharmacological and clinical efficacy.
Development of a Rapid Method for the Detection of Cocoa Butter Equivalents in Mixtures with Cocoa Butter
Authors: Barcarolo Robertino , Anklam Elke
Published: February 2020

A simple and rapid gas chromatographic (GC) method was developed for the detection of cocoa butter equivalents (CBEs) in cocoa butter (CB). It is based on the use of a 5 m nonpolar capillary column for the separation of the main triglycerides of CB according to their acyl/carbon numbers. The GC procedure was optimized to avoid thermal degradation of the triglycerides. By computing the ratio C54/C50 and (C54/C50) × C52 and by 2-dimensional plotting of these values, authentic CB samples were clearly distinguished from samples containing various CBEs. The detection of little as 1% CBE in CB (corresponding to about 0.3% CBE in chocolate) in a model system was shown to be possible. Under real conditions, for a wide range of CBs, about 2.5%CBEs in CB were detected. With this method, quantitation was possible at a concentration of 5% CBEs in CB mixtures, which corresponds to around 1% in chocolate; this value is far below the maximum level of 5% CBEs allowed to be added to chocolate.
Recognition of the Bouquet of Chinese Spirits by Artificial Neural Network Analysis
Authors: Chen Hua , Yu Zhiyong , Zhu Guobin
Published: February 2020

Forty-six samples of Chinese spirits, whose bouquets were determined by sensory evaluations, and 17 compounds characteristic of the flavors determined by gas chromatography/gas chromatography–mass spectrometry (GC/GC–MS), were subjected to neural network analysis and their corresponding factor scores developed. To make the bouquet recognition more efficient, an improved artificial back-propagation neural network (BPNN) was applied. In each kind of data, the BPNN was trained repeatedly until the error rate was less than the predetermined threshold error; then the trained network was applied to the test set that was not involved in the training process to establish the validity of the network, and a correct prediction rate of 100% was obtained. The BPNN provided a correlation between the data offered from sensory evaluations and the data of chemical compositions determined by instrumental analysis. The BPNN approach is feasible regardless of whether the crude data or the factor scores are used; however, recognition results were better with the latter than with the former. In a comparison of all the results obtained by BPNN, cluster analysis, and discriminant analysis, the method of artificial neural network analysis appeared to be the optimal technique for recognizing the bouquet of Chinese spirits.
Determination of Isoflavones in Soy and Selected Foods Containing Soy by Extraction, Saponification, and Liquid Chromatography: Collaborative Study
Authors: Klump Stephen P , Allred Maryann C , MacDonald John L , Ballam Joan M ,   Collaborators:, Arora A , Cole S , Collison M , Ellefson W , Gensic J , Hazebroek J , Johns P , Klump S , Lewis S , Moghaddam M , Murphy P , Woollard D C
Published: February 2020

Isoflavones are biologically active compounds occurring naturally in a variety of plants, with relatively high levels found in soybeans. Twelve laboratories participated in a collaborative study to determine the aglycon isoflavone content of 8 test samples of soy and foods containing soy. The analytical method for the determination of isoflavones incorporates a mild saponification step that reduces the number of analytes measured and permits quantitation versus commercially available, stable reference standards. Test samples were extracted at 65°C with methanol–water (80 + 20), saponified with dilute sodium hydroxide solution, and analyzed by reversed-phase liquid chromatography with UV detection at 260 nm. Isoflavone results were reported as μg/aglycon/g or μg aglycon equivalents/g. The 8 test samples included 2 blind duplicates and 4 single test samples with total isoflavone concentrations ranging from approximately 50 to 3000 μg/g. Test samples of soy ingredients and products made with soy were distributed to collaborators with appropriate reference standards. Collaborators were asked to analyze test samples in duplicate on 2 separate days. The data were analyzed for individual isoflavone components, subtotals of daidzin–daidzein, glycitin–glycitein, and genistin–genistein, and total isoflavones. The relative standard deviation (RSD) for repeatability was 1.8–7.1%, and the RSD for reproducibility was 3.2–16.1% for total isoflavone values of 47–3099 μg/g.
Determination of Chlormequat in Fruit Samples by Liquid Chromatography-Electrospray-Mass Spectrometry/Mass Spectrometry
Authors: Castro Rocio , Moyano Encarnación , Galceran Maria Teresa
Published: February 2020

An ion-pair liquid chromatography-mass spectrometry/mass spectrometry method was developed for the determination of chlormequat in fruit samples. A solid-phase extraction cleanup procedure with C18 cartridges was used. Sample preparation was simple and the achieved detection limit (0.03 mg/kg) and quantitation limit (0.08 mg/kg) were below the maximum residue levels legislated by the European Union. The chromatographic separation was performed by using a C8 column and heptafluorobutyric acid as ion pair reagent. The detection was conducted with an electrospray source and an ion trap as a mass analyzer. The reproducibility of the method gave good run-to-run (8–9%) and day-to-day (9–13%) precision values, and its applicability to the determination of chlormequat in pears and grapes, purées, and pear, apple, and grape juices was demonstrated.
Collection and Preparation of Sidestream Cigarette Smoke for Trace Elemental Determinations by Graphite Furnace Atomic Absorption Spectrometry and Inductively Coupled Plasma Mass Spectrometry
Authors: Wagner Karl A , McDaniel Reta , Self David
Published: February 2020

A novel method for the collection and preparation of sidestream cigarette smoke condensate is described for trace elemental analysis by inductively coupled plasma mass spectrometry and graphite furnace atomic absorption spectrometry. The smoke collection method utilizes a specially designed chimney that collects and directs the sidestream smoke (SS) to a 2-stage trapping system consisting of an impaction trap followed by a 0.8 μm mixed cellulose ester filter. The samples are digested with nitric acid in a commercial heating block before analysis. The method limits of detection (LODs) are 1, 0.2, 2, 9, 6, and 7 ng/cigt for As, Cd, Pb, Ni, Se, and Cr, respectively. The SS collected from an industry reference cigarette, 1R4F, produced by the University of Kentucky was analyzed. The concentrations of As, Cd, and Pb in 1R4F were determined to be 27.3 ± 2.1, 412 ± 14, and 43.8 ± 2.0 ng/cigt, respectively, while the concentrations of Ni, Cr, and Se are below the method LOD. Consequently, this novel method successfully addresses contamination, instrumentation, and collection issues for performing trace elemental analysis of sidestream cigarette smoke condensate.
Uptake of Cadmium, Copper, Iron, Manganese, and Zinc in Mushrooms (Boletaceae) from Croatian Forest Soil
Authors: Blanuša Maja , Kučak Antun , Varnai Veda-Marija , Sarić Marijana Matek
Published: February 2020

The concentration of trace elements (Cd, Cu, Fe, Mn, and Zn) was measured in different species of mushrooms (Boletaceae) and correlated with corresponding elements in soil. Five different species of Boletaceae mushrooms and soil samples were collected from forests of Varaždin county in Croatia. Trace elements were analyzed by atomic absorption spectrometry in mushrooms and in EDTA-extracted soil. The results showed that Cd, Cu, and Zn are concentrated in mushroom tissue from soil with transfer factors (mushroom/soil) of 27.0, 10.5, and 12.5, respectively. Cadmium incorporated much less in Leccinum (mean 0.73 mg/kg dry weight) than in Boletus, Xerocomus, or Gyroporus (respective means, 6.8, 8.4, and 12.3 mg/kg). Copper and Zn were accumulated in all collected mushrooms (14.7–35.6 and 109–179 mg/kg, respectively) with no difference among species. There was no accumulation of Fe and Mn in mushrooms, but concentrations differed between species, with lowest values in Leccinum. Iron varied from 31 to 878 mg/kg and Mn from 2.9 to 409 mg/kg. Correlations between elements in mushrooms and soil were significant only for Mn. Because no significant correlations for Cd, Cu, Zn, and Fe between mushrooms and soil were found, more studies are needed with only one species of mushrooms collected at locations with different levels of soil contamination. In spite of higher concentrations of Cd in some Boletaceae species, it is assumed that Cd intake through moderate mushroom consumption remains below suggested Provisional Tolerable Weekly Intake (FAO/WHO).
Multielemental Analysis of Food and Agricultural Matrixes by Inductively Coupled Plasma-Mass Spectrometry
Authors: Cubadda Francesco , Andrea Andrea , Testoni Antonella , Fabio Fabio
Published: February 2020

The suitability of quadrupole inductively coupled plasma-mass spectrometry (ICP-MS) for multielemental analysis of food following microwave closed vessel digestion of samples was evaluated in relation to analytical challenges presented by some major food and agricultural matrixes. Fifteen key analytes (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sn, V, Zn) were determined in 9 reference materials representative of 3 major groups of staple foods (cereals, seafood, and meat). For all measurements, the method of external calibration was used and Rh was selected as internal standard. Matrix-induced interferences were evaluated for each material, and suitable methods to overcome them were applied. Spectral interferences caused by C, Cl, and Ca content of digestates were quantitated and corrected by entering a simple system of mathematical correction equations into the instrument software before each analytical run. Full mastering of interferences together with adoption of a series of measures to control the reliability of analytical measurements produced accurate results for all the analytes. A standard analytical protocol is outlined for the benefit of both research and routine high-throughput laboratories that perform ICP-MS analyses of food.
Determination of Insecticides in Honey by Matrix Solid-Phase Dispersion and Gas Chromatography with Nitrogen–Phosphorus Detection and Mass Spectrometric Confirmation
Authors: Sánchez-Brunete Consuelo , Albero Beatriz , Miguel Ester , Tadeo José Luis
Published: February 2020

A multiresidue method was developed for the determination of 12 organophosphorus insecticides (diazinon, parathion methyl, fenitrothion, pirimiphosmethyl, malathion, fenthion, chlorpyrifos, quinalphos, methidathion, ethion, azinphosmethyl, coumaphos), one carbamate (pirimicarb), and one amidine (amitraz) in unifloral and multifloral honeys. The analytical procedure was based on the matrix solid-phase dispersion of honey on a mixture of Florisil and anhydrous sodium sulfate in small glass columns and subsequent extraction with a low volume of hexane–ethyl acetate (90 + 10, v/v), assisted by sonication. The insecticide residues were determined by capillary chromatography with nitrogen–phosphorus detection and confirmed by mass spectrometry. Average recoveries at the 0.05–0.5 μg/g levels were >80% for organophosphorus insecticides and about 60% for the other insecticides, pirimicarb and amitraz, with relative standard deviations <10%. The detection limit for the different insecticides ranged between 6 and 15 μg/kg. The main advantages of the proposed method are that extraction and cleanup are performed in a single step with a low volume of organic solvent. The method is simple, rapid, and less laborious than conventional methods. Several Spanish honeys were analyzed with the proposed method and no residues of the studied insecticides were found.
Liquid Chromatographic Determination of Multiple Sulfonamides, Nitrofurans, and Chloramphenicol Residues in Pasteurized Milk
Authors: Perez Norma , Gutierrez Rey , Noa Mario , Diaz Gilberto , Luna Hector , Escobar Irma , Munive Zenaida
Published: February 2020

A rapid and selective liquid chromatographic method was developed to detect 6 sulfonamides, 3 nitrofurans, and chloramphenicol residues in pasteurized milk. The 10 drugs were extracted with chloroform–acetone and the organic phase was evaporated; the residues were dissolved in an aqueous sodium acetate buffer solution 0.02M (pH = 4.8), and the fat was removed by washing with hexane. The aqueous layer was collected, filtered, and injected. The 6 sulfonamides and chloramphenicol were detected at 275 nm ultraviolet (UV) using a gradient system starting with sodium acetate buffer solution–acetonitrile (95 + 5) and finishing with sodium acetate buffer solution–acetonitrile (80 + 20). Nitrofurans were detected at 375 nm (UV) isocratically with sodium acetate buffer solution–acetonitrile (80 + 20). For 50 ppb fortified milk, the average recoveries were (sulfathiazole) 65.52%; (sulfamerazine) 75.36%; (sulfamethazine) 93.94%; (sulfachlorpyridazine) 75.94%; (sulfamethoxazole) 85.18%; (sulfamonomethoxine) 83.45%; (chloramphenicol) 104.17%; (nitrofurazone) 91.81%; (furazolidone) 100.76%; and (furaltadone) 72.38%. Method detection limits ranged from 4 ppb (nitrofurazone) to 16 ppb (sulfamethazine). Some matrix interferences (3–7 ppb) were observed only with sulfonamides.
Validation of a Simple Liquid Chromatographic Method for Determination and Quantitation of Residual Ivermectin and Doramectin in Pig Liver
Authors: Knold Lone , Reitov Marianne , Mortensen Anna Birthe , Hansen-Møller Jens
Published: February 2020

A rapid and quantitative method for the extraction, derivatization, and liquid chromatography with fluorescence detection of ivermectin (IVM) and doramectin (DOM) residues in porcine liver was developed and validated. IVM and DOM were extracted from the liver samples with acetonitrile, the supernatant was evaporated to dryness at 37°C under nitrogen, and the residue was reconstituted in 1-methylimidazole solution. After 2 min at room temperature, IVM and DOM were converted to a fluorescent derivative and then separated on a Hypersil ODS column. The derivatives of IVM and DOM were detected and quantitated with high specificity by fluorescence (excitation: 365 nm, emission: 475 nm). Abamectin was used as an internal standard. The mean extraction efficiencies from fortified samples (15 ng/g) were 75% for IVM and 70% for DOM. The limit of detection was 0.8 ng/g for both IVM and DOM.
Method Extension Study to Validate Applicability of AOAC Official Method 996.14 Assurance® Polyclonal Enzyme Immunoassay for Detection of Listeria monocytogenes and Related Listeria spp. from Environmental Surfaces: Collaborative Study
Authors: Feldsine Philip T , Lienau Andrew H , Leung Stephanie C , Mui Linda A ,   Collaborators:, Aharchi J , Aldridge I , Arling V , Bullard C , Carlson P , Cox C , Deiss K , Dillon J , Ellingson J , Fitzgerald S , Forgey R , Gailbreath K , Gallagher D , Geftman V , Herbst K , Hillis P , Johnson M , Koch S , Lewis D , Luepke J , McDonagh S , McGovern B , Moon B , Moreland L , Murray L , Richter D , Rucker C , Siu M-C , Smith C , Smith J , Stoltzfus E , Summers C , Taylor B , Toth J , White S , Witt J-L , Young S
Published: February 2020

Test portions from 3 environmental surface types, representative of typical surfaces found in a food production facility, were analyzed by the Assurance®Listeria Polyclonal Enzyme Immunoassay (EIA) and the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) culture method for Listeria monocytogenes and related Listeria species. In all cases, naturally contaminated environmental test samples were collected from an actual food production facility by sponge or swab. Test samples from concrete surfaces were collected by both swab and sponge; sponge test samples were collected from rubber surfaces, and swabs were used to sample steel surfaces. Test portions from each surface type were simultaneously analyzed by both methods. A total of 23 collaborators, representing government agencies, as well as private industry in both the United States and Canada, participated in the study. During this study, a total of 550 test portions and controls was analyzed and confirmed, of which 207 were positive and 336 were negative by both methods. Six test portions were positive by culture, but negative by the EIA. Three test portions were negative by culture, but positive by the EIA. Two test portions were negative by EIA and by culture, but confirmed positive when EIA enrichment broths were subcultured to selective agars. The data reported here indicate that the Assurance®Listeria EIA method and the USDA/FSIS culture method are statistically equivalent for detection of L. monocytogenes and related Listeria species from environmental surfaces taken by sponges or swabs.
Factors Affecting Multiresidue Determination of Priority Herbicides when Using Solid-Phase Microextraction
Authors: Lambropoulou Dimitra A , Konstantinou Ioannis K , Albanis Triantafyllos A
Published: February 2020

A solid-phase microextracton (SPME) procedure was developed for the determination of 10 selected organonitrogen herbicides (s-ethyl dibropylthiocarbamate [EPTC], molinate, propachlor, trifluralin, simazine, atrazine, propazine, terbuthylazine, alachlor, and prometryn) and was tested with various natural waters. Gas chromatography coupled with flame thermionic and mass spectrometric detection was used for quantitation. For this purpose, polydimethylsiloxane and polyacrylate fibers were used and the factors affecting the SPME process such as pH, ionic strength, methanol content, memory effect, stirring rate, and adsorption-time profile were investigated and optimized. By using spiked liquid chromatography water, optimal factors were determined to be 25% salt, <0.5% methanol, stirring rate of 960 rpm, pH 4, and an equilibrium time of 30 min. These conditions were used in further studies of the fibers and in analysis of natural water samples. The method was applied to spiked natural waters such as ground water, sea water, lake water, and river water at a concentration range of 0.5–10 μg/L. Limits of detection ranged from 5 to 90 ng/L, and precision ranged from 5 to 15% (as relative standard deviation), depending on the pesticide, fiber, and detector used. The recoveries of herbicides were 70.2–118.4%, and the average r2 values of the calibration curves were >0.99 for all analytes. The results demonstrate the suitability of the SPME method to determine these organonitrogen herbicides in various natural waters. River water samples originating from the Epirus region (Northwestern Greece) were analyzed to verify the performance of the optimized method by comparing the results obtained by SPME with those obtained by using conventional solid-phase extraction of the selected herbicides.
Detection and Isolation of Listeria monocytogenes from Food Samples: Implications of Sublethal Injury
Authors: Donnelly Catherine W
Published: February 2020

Detection of L. monocytogenes is often limited by the performance of the enrichment media used to support bacterial growth to detectable levels. Because Listeria may exist at extremely low levels in foods, sample enrichment protocols must amplify these low initial populations to detectable limits. Listeria may also exist in an injured state in food products as a result of processing treatments such as heating, freezing, exposure to acids, or exposure to sanitizing compounds. Selective agents in enrichment media normally used for recovery of Listeria may inhibit repair and detection of sublethally injured Listeria, which may go on to repair, grow, and regain pathogenicity. Simple modifications to existing regulatory protocols, such as those that use more than one enrichment broth, raise sensitivity of detection to 90%. This review shows the efficacy of repair/enrichment strategies, which increase sensitivity of detection to 97.5–98.8% compared with 65–70% by standard regulatory protocols. Ribotype analysis of isolates obtained from meat samples reveals a complex microbial ecology, with striking differences in both number and distribution of distinct genetic types of Listeria, depending upon whether samples are enriched in selective or repair/enrichment media. In studies on enrichment of dairy environmental samples in University of Vermont medium and Listeria repair broth (UVM and LRB), combining these 2 primary enrichment media into a single tube of Fraser broth for dual secondary enrichment yielded a significantly higher percentage (p < 0.05) of Listeria-positive samples than did use of either LRB or UVM alone. Refinement of conventional Listeria recovery methods should consider the importance of the enrichment step, the nutritional needs of specific genetic types, and the physiological condition of Listeria isolates in foods.
Polymerase Chain Reaction-Based Methods for Detection of Listeria monocytogenes: Toward Real-Time Screening for Food and Environmental Samples
Authors: Norton Dawn M
Published: February 2020

A review is presented of nucleic acid amplification-based methodology, specifically polymerase chain reaction (PCR)-based assays, for the detection of Listeria monocytogenes in food and environmental samples. Until recently, developmental challenges including poor sensitivity, due in part to reaction inhibition by components of the sample matrix, and the potential for false-positive reactions have limited routine application of PCR-based screening assays. Commercial assays address these challenges while offering convenient, standardized protocols, a high level of automation, and results within 2 days after the sampling date. Although sample enrichment is necessary to achieve desired detection limits, continued efforts toward template purification will facilitate the development of assays offering real-time, quantitative results. The development of ribonucleic acid (RNA) amplification-based assays may increase in importance, particularly if end-product testing is prioritized by regulatory agencies, as messenger RNA appears to serve as an accurate indicator of cell viability. Further, the increase in target copy number may improve assay sensitivity. PCR-based screening methods offer efficient, reliable results and are ideal for monitoring the presence of L. monocytogenes in foods and in the food processing environment.
Molecular Subtyping Methods for Listeria monocytogenes
Authors: Wiedmann Martin
Published: February 2020

Conventional, phenotypic, and DNA-based subtyping methods allow differentiation of Listeria monocytogenes beyond the species and subspecies level. Bacterial subtyping methods not only improve our ability to detect and track human listeriosis outbreaks, but also provide tools to track sources of L. monocytogenes contamination throughout the food system. The use of subtyping methods also provides an opportunity to better understand the population genetics, epidemiology, and ecology of L. monocytogenes. The last 5 years have seen tremendous advancements in the development of sensitive, rapid, automated, and increasingly easy-to-use molecular subtyping methods for L. monocytogenes. This review highlights key aspects of different L. monocytogenes subtyping methods and provides examples of their application in public health, food safety, population genetics, and epidemiology. A significant focus is on the application of subtyping methods to define L. monocytogenes subtypes and clonal groups, which may differ in phenotypic characteristics and pathogenic potential.
Assessment of MIST Alert™, a Commercial Qualitative Assay for Detection of Paralytic Shellfish Poisoning Toxins in Bivalve Molluscs
Authors: Mackintosh Fiona H , Gallacher Susan , Shanks Aileen M , Smith Elizabeth A
Published: February 2020

A recently developed commercial rapid test kit (MIST Alert™) was assessed for determination of the presence of paralytic shellfish poisoning (PSP) toxins in shellfish. Several commercially important shellfish species obtained from the UK shellfish toxin monitoring program, containing a range of total PSP toxicities as determined by the mouse bioassay (MBA), were tested. The kit detected toxin in all samples containing the European Community tolerance level of 80 μg saxitoxin (STX) equivalents/100 g shellfish flesh as determined by the MBA. With one exception, the kit detected toxin in all samples that contained >40 μg STX equivalents/100 g according to the MBA. Among samples in which the MBA did not detect toxin, the kit disagreed in 25% of the tests, although further analysis by liquid chromatography (LC) and MBA of some samples confirmed the presence of toxins. These results suggest that MIST Alert may be suitable as an initial screen for PSP toxins as part of routine monitoring programs, thereby greatly reducing the number of MBAs. Trials were also performed by nonscientific personnel to evaluate the ease of use and interpretation of results obtained by MIST Alert. The results indicated that the kits could be readily used and accurately interpreted by individuals with no technical or scientific background.
Identity Preservation of Genetically Modified Organisms in the Food Chain: Requirements, Methods, and Costs
Authors: Brookes Graham
Published: February 2020

The use of the technology of genetic modification (GM) in European agriculture and the food supply chain is currently controversial. Because of strong anti-GM technology sentiments, the use of ingredients derived from plants containing GM have largely been eliminated from foods manufactured for direct human consumption by the food supply chain in much of the European Union (EU). During the past year, the attention of those opposed to the technology has turned to the use of GM ingredients in livestock production systems by incorporation of GM soy and maize in animal feed. A discussion is presented of the key issues relating to this subject, focusing on how supplies of GM or non-GM products are segregated or how their identities are preserved. The discussion is centered on GM maize and soybeans into which agronomic traits, such as herbicide tolerance and/or insect resistance, have been incorporated. These are currently the only crops into which some varieties containing GM have been approved for use in the EU.
Detection and Identification of Zeranol in Chicken or Rabbit Liver by Liquid Chromatography-Electrospray Tandem Mass Spectrometry
Authors: Fang Xiaoming , Chen Jiahua , Guo Dehua , Wang Guoquan
Published: February 2020

A sensitive, specific, and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for detection and identification of zeranol in chicken or rabbit liver. A homogenized liver sample was hydrolyzed with β-glucuronidase/arylsulfatase, and the hydrolysate was extracted with ethyl ether. The supernatant was evaporated to dryness, and the residue was dissolved in chloroform and re-extracted with sodium hydroxide. After acidification, the extract was cleaned up on a C18 solid-phase extraction cartridge and analyzed by electrospray LC-MS/MS in the negative ion mode. The multiple reaction monitoring transition from both m/z 321 to 277 and m/z 321 to 303 was monitored for confirmation, and the product ion of 277 was used for quantitation. Separation was performed on a Waters XTettra™ C18 column (50 × 2.1 mm, 3.5 μm) combined with a safeguard column (Symmetry C18, 20 × 3.9 mm, 5 μm), using a gradient elution with acetonitrile and 20mM ammonium acetate. Calibration curves were prepared and good linearity was achieved over the concentration ranges tested. For all liver samples fortified at 3 different levels of 1, 5, and 50 μg/kg, the overall recoveries and relative standard deviations were in the range of 61–90 and 8–13%, respectively. The limit of quantitation based on the assay validation was 1 μg/kg. The method had been used on a routine basis for detection and identification of zeranol in liver samples.
Sensitive and Rapid Spectrophotometric Methods for Determination of Anticancer Drugs
Authors: Nagaraja Padmarajaiah , Vasantha Ramanathapura A , Yathirajan Hemmige S
Published: February 2020

Sensitive, rapid, and simple spectrophotometric methods were developed for determination of the anticancer drugs vinblastine sulfate (VBS) and vincristine sulfate (VCS), which belong to the class of vinca alkaloids. The first method is based on the reaction of VBS and VCS with diazotized dapsone, forming yellow azo products with absorption maxima at 430 nm. The colored species obey Beer's law in the concentration range of 0.5–24 μg/mL for VBS and 0.5–12 μg/mL for VCS. The second method describes the reaction of VBS and VCS with iron(III) and subsequent reaction with ferricyanide in hydrochloric acid medium to yield blue products with absorption maxima at 750 nm. The Beer's law range for this method is 0.1–4 μg/mL for VBS and 0.5–10 μg/mL for VCS. With both methods, colored species were stable for 1 h. The methods are simple and reproducible and are applied for determination of VBS and VCS in pharmaceutical formulations. Commonly encountered pharmaceuticals added as excipients do not interfere in the analysis and the results obtained in the analysis of dosage forms agree well with the labeled contents.