bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Phenolic Xenoestrogens in Environmental Samples by Liquid Chromatography with Mass Spectrometric Detection
Authors: Petrović Mira , Barceló Damià
Published: February 2020

A method is proposed for the determination of several phenolic xenoestrogens in aqueous and solid environmental samples. The method uses solid-phase extraction (preceded by ultrasonic solvent extraction for solid samples), reversed-phase liquid chromatographic separation, and mass spectrometric detection using both atmospheric pressure chemical ionization and electrospray ionization. This method was developed to support several studies undertaken to obtain aquatic and sedimentary data for rivers and seashores in Spain that are likely to be contaminated by endocrine-disrupting compounds (EDCs) as a consequence of wastewater discharge. Nonylphenol polyethoxylates (NPEOs), nonylphenoxy carboxylates (NPECs), nonylphenol (NP), octylphenol (OP), and bisphenol A (BPA) were determined in various samples of surface water and sediment, collected at different locations upstream and downstream from outfalls of municipal wastewater treatment plants (WWTPs). Seawater and marine sediments were collected in different harbor areas in Spain. Additionally, WWTP influent and effluents were analyzed to monitor the occurrence and transformation of phenolic EDCs during physicochemical and biological treatment. Rather high concentrations of the compounds investigated were found in some samples. Concentrations of NP were ≤590 μg/kg in sediments and ≤15 μg/L in water samples. NPEOs and NPECs were found in water samples in concentrations ≤41 and ≤35 μg/L, respectively. In solid samples (river sediment), concentrations of NPEO were ≤818 μg/kg and those of NP1EC were 95 μg/kg.
Culture Age and Drying Time as Variables of the AOAC Sporicidal Test
Authors: Miner Norman A , Taylor Michelle A , Bernal Sara E , Harris Valerie L , Sichinga Mashike J
Published: February 2020

In the United States, the AOAC Sporicidal Activity of Disinfectants Method 966.04 is the standard for identifying a liquid chemical germicide as a sterilant. Furthermore, the highest level of a disinfectant must also be a sterilant as defined by Method 966.04, when used in its sterilant mode for a longer exposure time. The AOAC Sporicidal Test is also used as a part of the standard test methods to define a sterilant for Australia and the European Union. Many laboratories have identified variables of this test that can affect the sterilization exposure time for sterilants, or even the ability to classify a chemical as a sterilant. Method 966.04 requires spore-labeled porcelain penicylinders (cylinders) and silk suture loops, collectively referred to as carriers, to be dried for 24 h, but allows these carriers to be used for at least 7 days, in effect allowing a drying time of 24 h to at least 7 days. We tested the resistance of cylinders that had been labeled with Bacillus subtilis spores cultured for 72, 96, and 120 h, and dried for 24, 48, and 72 h against a 60 min exposure to 2.0%alkaline glutaraldehyde, and 2, 5, 10, 15, and 20 min exposures to 2.5N HCl. All the culture incubation and drying times met the standard of resistance to 2.5N HCl for at least 2.0 min at 20°C, and all carriers contained at least 105 colony-forming units (CFU) of B. subtilis per carrier. However, for 3 repeated tests, regardless of incubation time, an average of 96%of the carriers were sterilized by the 2.0%glutaraldehyde after drying for 24 h, and an average of 61%were sterilized after drying for 48 or 72 h. We propose that the variable of drying time be eliminated from Method 966.04.
Determination of Organochlorine Pesticides and Chlorobenzenes in Strawberries by Using Accelerated Solvent Extraction Combined with Sorptive Enrichment and Gas Chromatography/Mass Spectrometry
Authors: Wennrich Luise , Popp Peter , Köller Gábor , Breuste Jürgen
Published: February 2020

An analytical scheme for the determination of several organochlorine pesticides like hexachlorocyclohexanes (HCHs) and DDX compounds (p,p′-DDE, p,p′-DDD, and p,p′-DDT) as well as chlorobenzenes in strawberries has been developed. The procedure is based on aqueous accelerated solvent extraction (ASE) followed by solidphase microextraction (SPME) or stir bar sorptive extraction (SBSE) and subsequent thermodesorption–gas chromatography/mass spectrometry analysis. A 65 μm polydimethylsiloxane/divinylbenzene fiber was chosen for the SPME experiments. Significant SPME and ASE parameters were optimized using spiked water and strawberry samples. For the ASE of the organochlorine compounds, a water–acetone mixture (90 + 10, v/v) as the extraction solvent, an extraction temperature of 120°C, and 2 cycles of 10 min extraction proved optimal. The developed method was evaluated with respect to precision and limits of detection (LOD). The relative standard deviations of replicate ASE–SPME determinations (n = 5) were in the range of 4–24%. LOD values between 1 and 10 μ g/kg were achieved with the exception of DDT and DDE (40 μg/kg). Using SBSE, the LOD of these compounds could be improved (2 and 5 μg/kg). The main advantages of this method are the avoidance of cleanup and concentration procedures as well as the significant reduction of the required volume of organic solvents. The described method was applied to the determination of the pollutants in strawberry samples collected from different allotment gardens in a potentially polluted area, the Bitterfeld-Wolfen region (Germany).
The Role of Planar Chromatography in Medicinal Plant Research
Authors: Nyiredy Szabolcs
Published: February 2020

This paper summarizes the role of planar chromatography (PC) in medicinal and aromatic plant (MAP) research and development, and demonstrates the importance of the technique, after extraction, in the analysis of MAP (identification and quantitative determination of the separated compound/s), in the purification and isolation process, and in different types of screening procedure. Special attention is paid to analytical, micropreparative and preparative forced-flow techniques, for example overpressured-layer chromatography (OPLC) and rotation planar chromatography (RPC). The special features of analytical, micropreparative, and preparative layer chromatography (PLC), OPLC, and RPC are compared in tables. Purification and isolation procedures using forced-flow techniques are shown in flowcharts. Some applications, relating to different classes of substance, are presented to demonstrate the versatility of various planar chromatographic techniques.
Application of High-Performance, Thin-Layer Chromatography to Quality Control of Antimetabolite Analogue Infusion Bags
Authors: Perello Laurent , Demirdjian Sylvie , Dory Alexandre , Bourget Philippe
Published: February 2020

A global postproduction quality program was developed to secure chemotherapy infusion at the Gustave Roussy Institute. Despite rigorous procedures and computerized prescriptions, an analytical check was necessary to improve the quality of ready-to-use solutions of cytotoxic drugs in our Centralized Antineoplastics Reconstitution Unit. High-performance, thin-layer chromatography was selected as the analytical tool to assay 12 anticancer drugs. One of the analytical methods can separate 4 antimetabolite substances, i.e., fludarabine (FDB), cytarabine (CTB), gemcitabine (GTB), and fluorouracil (5 FU). For all infusion bags manufactured, up to 26 samples could be assayed per series using a double standard calibration (GTB and 5 FU).
Determination of Clopidol Residues in Chicken Tissues by Liquid Chromatography: Part III. Quality Control Analysis of Export Chickens
Authors: Pang Guo-Fang , Cao Yan-Zhong , Fan Chun-Lin , Zhang Jin-Jie , Li Xue-Min
Published: February 2020

A summary is presented of the liquid chromatographic (LC) determination of clopidol residues in export chickens from 1992 to 1999. Over the past 8 years, we analyzed >7000 chicken samples. A total of 0.66% of samples contained clopidol residues, ranging from 0.005 to 0.79 mg/kg; however, none exceeded 3 mg/kg, the Chinese maximum residue limit. In comparison with 1992, the number of samples multiplied 70-fold, and the frequency of clopidol found in samples decreased 148-fold in 1999. The chickens inspected were exported to foreign countries; all were cleared by the buyers with no disputes. This report also introduces the critical control points of the proposed LC method as well as identification of false-positive procedures by both experience and LC/mass spectrometric confirmation. Our experiences over the past 8 years have demonstrated that the ruggedness of the proposed LC method is quite good.
Liquid Chromatographic/Mass Spectrometric Determination of Desmedipham and Phenmedipham and Their Metabolites in Soil
Authors: Perret Daniela , Gentili Alessandra , Marchese Stefano , Marino Aldo , Bruno Federica
Published: February 2020

A simple method is described for the simultaneous determination of residues of 2 carbamate herbicides (phenmedipham and desmedipham) and related metabolites (m-aminophenol, aniline, and m-toluidine) in soil. The analytes are extracted from spiked soils with methanol. The solvent/soil suspension is centrifuged, and the supernatant is directly injected, without any further cleanup, into a reversed-phase liquid chromatography/mass spectrometry apparatus equipped with a TurboIonSpray interface. The method was tested on 5 soils having different physicochemical properties. Recoveries from the soil types, spiked over the range of 50–200 ppb, were essentially quantitative for each analyte. The detection limits of the method are ≤25 ng/g.
Determination of N-Nitrosodimethylamine in Environmental Aqueous Samples by Isotope-Dilution GC/MS–SIM
Authors: Raksit Asit , Johri Saima
Published: February 2020

An analytical method for the determination of N-nitrosodimethylamine (N-NDMA) in environmental aqueous samples has been developed using isotope dilution gas chromatography/mass spectrometry in the selected ion monitoring mode (GC/MS–SIM). After deuterated N-nitrosodimethylamine (d6-N-NDMA) as surrogate standard was added to the samples, the analytes were extracted with methylene chloride, dried with anhydrous sodium sulfate, and concentrated in a rotary evaporator. The concentrated extracts were analyzed by GC/MS–SIM after adding N-nitrosodiethylamine as an internal standard. The method detection limit for N-NDMA was 0.003 pg/μL and was validated by an analysis of a fortified water sample. The method was applied to real samples.
Determination of Zearalenone Content in Cereals and Feedstuffs by Immunoaffinity Column Coupled with Liquid Chromatography
Authors: Fazekas Bela , Tar Andrea
Published: February 2020

The zearalenone content of maize, wheat, barley, swine feed, and poultry feed samples was determined by immunoaffinity column cleanup followed by liquid chromatography (IAC–LC). Samples were extracted in methanol–water (8 + 2, v/v) solution. The filtered extract was diluted with distilled water and applied to immunoaffinity columns. Zearalenone was eluted with methanol, dried by evaporation, and dissolved in acetonitrile–water (3 + 7, v/v). Zearalenone was separated by isocratic elution of acetonitrile–water (50 + 50, v/v) on reversed-phase C18 column. The quantitative analysis was performed by fluorescence detector and confirmation was based on the UV spectrum obtained by a diode array detector. The mean recovery rate of zearalenone was 82–97% (RSD, 1.4–4.1%) on the original (single-use) immunoaffinity columns. The limit of detection of zearalenone by fluorescence was 10 ng/g at a signal-to-noise ratio of 10:1 and 30 ng/g by spectral confirmation in UV. A good correlation was found (R2 = 0.89) between the results obtained by IAC–LC and by the official AOAC–LC method. The specificity of the method was increased by using fluorescence detection in parallel with UV detection. This method was applicable to the determination of zearalenone content in cereals and other kinds of feedstuffs. Reusability of immunoaffinity columns was examined by washing with water after sample elution and allowing columns to stand for 24 h at room temperature. The zearalenone recovery rate of the regenerated columns varied between 79 and 95% (RSD, 3.2–6.3%). Columns can be regenerated at least 3 times without altering their performance and without affecting the results of repeated determinations.
Detection of Preformed Type A Botulinal Toxin in Hash Brown Potatoes by Using the Mouse Bioasssay and a Modified ELISA Test
Authors: Ferreira Joseph L , Eliasberg Stacey J , Harrison Mark A , Edmonds Paul
Published: February 2020

A foodborne illness caused by type A toxin-producing Clostridium botulinumwas investigated by using the standard mouse bioassay and a rapid invitro test for toxin detection. The patient, who consumed improperly stored hash brown potatoes that contained the preformed toxin, was diagnosed with type A botulism. C. botulinum type A toxin was detected in the hash brown potatoes as well as in the tryptone–peptone–glucose–yeast extract (TPGY) medium subcultures of this food using the mouse bioassay and an amplified ELISA technique. The mouse bioassay revealed preformed toxin at 10 000 minimum lethal dose (MLD)/g uncooked product and the amplified ELISA an equivalent 50 000 MLD/g. The cultural toxin from the uncooked product killed mice at the 106 dilution and a modification of the ELISA procedure was positive at the 103 dilution. Cooked food obtained from the consumer's waste can contained 100 MLD/g and the ELISA was also positive at the same dilution of the product. The culture of the cooked product obtained from the waste can was lethal for mice at the 107 dilution and positive using the modified ELISA at the 104 dilution. The unmodified amplified ELISA method indicated a toxin level of approximately 1 ng/mL (equivalent to 5 × 105 MLD/mL) in diluted culture fluid from the uncooked food and the culture of cooked food obtained from the waste can. The hash brown potatoes were negative for types B, E, and F preformed and cultural botulinal toxins using both assays.
Detection of Added Beet or Cane Sugar in Maple Syrup by the Site-Specific Deuterium Nuclear Magnetic Resonance (SNIF-NMR®) Method: Collaborative Study
Authors: Martin Yves-Loïc ,   Collaborators:, Christoph N , Blanch-Cortès A -I , Dennis J , Giraudon S , Guillon C , Hermann A , Le Leuch A , Mazac J , Naulet N , Parent M -J , Remaud G , Wittkowski R
Published: February 2020

Results of a collaborative study are reported for the detection of added beet or cane sugar in maple syrup by the site-specific natural isotope fractionation–nuclear magnetic resonance (SNIF-NMR®) method. The method is based on the fact that the deuterium content at specific positions of the sugar molecules is different in maple syrup from that in beet or cane sugar. The syrup is diluted with pure water and fermented; the alcohol is distilled with a quantitative yield and analyzed with a high-field NMR spectrometer fitted with a deuterium probe and fluorine lock. The proportion of ethanol molecules monodeuterated at the methyl site is recorded. This parameter (D/H)I is decreased when beet sugar is added and increased when cane sugar is added to the maple syrup. The precision of the method for measuring (D/H)I was found to be in good agreement with the values already published for the application of this method to fruit juice concentrates (AOAC Official Method 995.17). An excellent correlation was found between the percentage of added beet sugar and the (D/H)I isotopic ratio measured in this collaborative study. Consequently, all samples in which exogenous sugars were added were found to have a (D/H)I isotopic ratio significantly different from the normal value for an authentic maple syrup. By extension of what is known about plants having the C4 cycle, the method can be applied to corn sweeteners as well as to cane sugar. One limitation of the method is its reduced sensitivity when applied to specific blends of beet and cane sugars or corn sweeteners. In such case, the C13 ratio measurement (see AOAC Official Method 984.23, Corn Syrup and Cane Sugar in Maple Syrup) may be used in conjunction.
Determination of Fat in Dairy Products Using Pressurized Solvent Extraction
Authors: Richardson Russell K
Published: February 2020

Gravimetric fat data were obtained for a wide range of dairy products with fat contents ranging from 0.5 to 83% using pressurized solvent extraction at elevated temperatures and pressure (80–120°C; 10.3 MPa). Extraction performance was sensitive to solvent composition, temperature, and sample matrix. By optimizing solvent mixtures, sample–solvent contact times of 8–10 min were sufficient for high recoveries from all products tested. The most successful solvents with regard to speed of extraction, selectivity, and recovery (average recovery, %) were various mixtures of hexane (or petroleum ether)–dichloromethane–methanol for dried cream (99.8%), dried whole milk (99.6%), dried buttermilk (98.2%), dried skim milk (97.0%), dried whey protein concentrate (97.5%), casein (95.0%), and caseinate (102.1%); petroleum ether–acetone–ethanol or petroleum ether–acetone–isopropanol for cheddar-type cheese (99.4%); petroleum ether–acetone for butter (99.9%); petroleum ether–acetone–isopropanol for cream (100.3%); and petroleum ether–isopropanol for liquid milks (99.0%). Relative standard deviations for repeatability were obtained for dried whole milk (0.2%), dried whey protein concentrate (0.7%), cheese (0.3%), butter (0.1%), and ultraheat treated (UHT) milk (0.7%). Solvent removal and drying of extracts with a heated block evaporator saved time compared with conventional drying ovens. Estimated savings in labor (50–75%) and solvents (80%) were substantial compared with the manual Mojonnier methods.
Application of a Mixed-Mode Solid-Phase Extraction and Cleanup Procedure for LC/MS Determination of Thiabendazole and Carbendazim in Apple Juice
Authors: Young Michael S , Early Michael F , Mallet Claude R , Krol Jim
Published: February 2020

Recently, a mixed-mode solid-phase extraction (SPE) procedure was developed for rapid extraction and cleanup for determination of the fungicides thiabendazole and carbendazim in various fruit juices. This paper reports the application of that sample preparation procedure to the liquid chromatographic/mass spectrometric determination of these fungicides in apple juice with detection by positive electrospray ionization mass spectrometry (ESI/MS). Response was linear for sample concentrations from 2 to 500 μg/L (ppb). Recoveries averaged 74% (9% RSD) for carbendazim and 93% (9% RSD) for thiabendazole. After SPE cleanup, no matrix supression was observed for the ESI+ response for either compound studied. The method was applied to the analysis of incurred residues in 4 store-bought apple juices; carbendazim levels ranged from 10 to 70 μg/L and thiabendazole levels ranged from less than 2 to 130 μg/L.
Review and Assessment of In Vitro Detection Methods for Algal Toxins
Authors: Dolah Frances M van , Ramsdell John S
Published: February 2020

Algal toxins produced by marine and freshwater microalgae present a significant analytical challenge because of their complex structures and frequent occurrence as mixtures of structural congeners, which differ in toxic potencies and are present at varying proportions in contaminated samples. Rapid, sensitive in vitro detection methods specific for each class of algal toxins have been developed over the past decade, including immunoassays, enzyme inhibition assays, receptor assays, and cell assays. This review discusses the conceptual approaches to assay development and provides a detailed assessment of the use of in vitro detection methods for marine and freshwater algal toxins.
Novel Approach to the Study of the Chiral Discrimination Mechanism in a Series of Dansyl Amino Acids
Authors: Guillaume Yves-Claude , Guinchard Christiane , Tong Truong Thanh , Thomassin Mireille
Published: February 2020

With poly(octadecylsiloxane) as the liquid chromatographic stationary phase, phosphate buffer as the mobile phase, a series of D- and L-dansyl amino acids as solutes, and β-cyclodextrin as the chiral selector, a study was conducted of the hydrophobic effect on both the solute complexation with the chiral selector and chiral discrimination mechanisms by varying the sucrose concentration in the mobile phase and the column temperature. The number of sucrose molecules excluded during the solute complexation with the chiral selector proved to be a good marker of the solute inclusion in the cavity. Gibbs Helmotz parameters Δ(ΔH) and Δ(ΔS) between D- and L-enantiomers were determined from plots of the logarithm of the intrinsic selectivity versus the reciprocal of the temperature. The results obtained predicted that the enantioselectivity was related to the bulkiness of the solute. This numerical approach is a valuable tool in the exploration of the steric effects implied in the formation of the host-guest complex.
Simultaneous Determination of Binary Mixtures of Sulfonylurea Herbicides in Water by First-Derivative Photochemically Induced Spectrofluorimetry
Authors: Coly Atanasse , Aaron Jean-Jacques
Published: February 2020

First-derivative photochemically induced spectrofluorimetry (PIF-1D) is applied to the simultaneous determination of binary mixtures of 4 sulfonylurea herbicides in aqueous micellar samples. Synthetic binary mixtures of sulfometuronmethyl with chlorsulfuron, metsulfuron-methyl, and 3-rimsulfuron, respectively, are well resolved by using the zero-crossing point procedure. PIF-1D allows the determination of binary mixtures of these herbicides with linear dynamic ranges over about 2 orders of magnitude, limits of detection between 0.5 and 52 ng/mL, and relative standard deviations within 0.3–2.9%. Application to the determination of binary mixtures of these herbicides in spiked tap water samples yielded satisfactory recoveries (90–117%).
Speciation Analysis of Heavy Metals in Natural Waters: A Review
Authors: Fytianos Konstantinos
Published: February 2020

Metal speciation in natural waters is of increasing interest and importance because toxicity, bioavailability, environmental mobility, biogeochemical behavior, and potential risk in general are strongly dependent on the chemical species of metals. This paper provides an overview of the need for speciation of heavy metals in natural waters, the chemical and toxicological aspects of speciation, and the analytical procedures for separation and the different techniques for final determination that are used today. The trends and developments of speciation are also discussed. Finally, the case of chromium (Cr) was selected for a detailed presentation because the speciation of this metal has attracted a great deal of interest in view of the toxic properties of Cr(VI).
Application of Membrane Filters for Spectrophotometric Determination of Cationic Surfactants in River Water and Sediment
Authors: Hui-Feng Sun , Takamori Miwa , Hata Noriko , Kasahara Issei , Taguchi Shigeru
Published: February 2020

Cationic surfactant (CS+) in urban river water and sediment was extracted and determined spectrophotometrically with 2 membrane filters. The CS+ in the water samples, mostly in the form of an ion associate with the coexisting anionic surfactant (AS−), was collected on a polytetrafluoroethylene (PTFE) membrane filter and eluted with methanol. Bromphenol blue (BPB), hydrochloric acid, and water were added to the methanol solution successively, and the mixed solution was filtered through a mixed cellulose ester membrane filter. The CS+-BPB− ion associate, formed by a counter ion exchange, was collected on the filter and dissolved into N,N-dimethylformamide (DMF) together with the mixed cellulose ester membrane filter. After addition of 2 drops of triethanolamine, the absorbance of the DMF solution was measured. The CS+ in sediment samples was extracted with methanol by ultrasonic irradiation; the methanol solution was then passed through a PTFE membrane filter and evaporated to dryness. The CS+ was redissolved in a small amount of methanol. For water samples, recoveries and relative standard deviations for 0.30 μM benzyldimethyltetradecylammonium ion, a standard material, were ≥93 and ≤5%, with a detection limit of 0.02 μM. Concentrations of CS+ in sediments were much higher than those in water samples, indicating that CS+ is adsorbed on the surface of the sediment.
Determination of Fumonisins B1 and B2 in Corn and Corn Flakes by Liquid Chromatography with Immunoaffinity Column Cleanup: Collaborative Study
Authors: Visconti Angelo , Solfrizzo Michele , Girolamo Annalisa De ,   Collaborators:, Bresch H , Burdaspal P , Castegnaro M , Felgueiras I , Gardikis J , Jørgensen K , Kakouri; E , Kretschmer H , Lew H , Meyer K , Miller J , Møller T , Nuotio K , Patel S , Pietri A , Pittet A , Sizoo E , Spanjer; M C , Steiner W , Tiebach R , Usleber E , von Holst C , Wilson P
Published: February 2020

A liquid chromatographic (LC) method for the determination of fumonisins B1 (FB1) and B2 (FB2) in corn and corn flakes was collaboratively studied by 23 laboratories, which analyzed 5 blind duplicate pairs of each matrix to establish the accuracy, repeatability, and reproducibility characteristics of the method. Fumonisin levels in the corn ranged from <0.05 (blank) to 1.41 μg/g for FB1 and from <0.05 to 0.56 μg/g for FB2, whereas in the corn flakes they ranged from <0.05 to 1.05 μg/g for FB1 and from <0.05 to 0.46 μg/g for FB2. The method involved double extraction with acetonitrile–methanol–water (25 + 25 + 50), cleanup through an immunoaffinity column, and LC determination of the fumonisins after derivatization with o-phthaldialdehyde. Relative standard deviations for the within-laboratory repeatability (RSDr) of the corn analyses ranged from 19 to 24% for FB1 and from 19 to 27% for FB2; for the corn flakes analyses, RSDr ranged from 9 to 21% for FB1 and from 8 to 22% for FB2. Relative standard deviations for the between-laboratories reproducibility (RSDR) of the corn analyses ranged from 22 to 28% for FB1 and from 22 to 30% for the FB2; for corn flakes analyses, RSDR ranged from 27 to 32% for FB1 and from 26 to 35% for FB2. Mean recoveries of FB1 and FB2 from corn spiked with FB1 at 0.80 μg/g and with FB2 at 0.40 μg/g were 76 and 72%, respectively; for corn flakes spiked at the same levels recoveries were 110 and 97% for FB1 and FB2, respectively. HORRAT ratios for the analyses of corn ranged from 1.44 to 1.53 for FB1 and from 0.96 to 1.48 for FB2, whereas for corn flakes they ranged from 1.60 to 1.82 for FB1 and from 1.39 to 1.68 for FB2.
Semiautomatic Flow-Injection Method for Determination of Volatile Acidity in Wines
Authors: González-Rodríguez José , Pérez-Juan Pedro , Castro Maria Dolores Luque de
Published: February 2020

A flow-injection (FI) method based on analytical pervaporation was assessed for its routine use in the determination of volatile acidity in winery laboratories. The new method was compared with both the official method and the Mathieu method, which is most often used in Spanish wineries, by testing 30 different wines, including young and aged, and sweet and dry wines from Montilla-Moriles appellation d'origine. The robustness of the new method was established, and then all 3 methods were studied in terms of range of linearity and regression of the calibration curve, repeatability, reproducibility, sensitivity, detection and quantitation limits (LOD and LOQ, respectively), and time of analysis. The FI method surpassed the Mathieu method in reproducibility and both the Mathieu and official methods in LOD and LOQ and sensitivity; it also required less personnel involvement and shorter analysis time. The statistical criteria established by the Office International de la Vigne et du Vin were applied to the data and the results obtained indicated that the differences between the analytical parameters of the 3 methods are not significant and can be applied indistinctly. The correlation of the methods was studied by taking them 2 by 2, and the corresponding equations, coefficients, and deviations confirmed the statistical results. Thus, the new method can be used in winery laboratories with clear advantages over its 2 counterparts (the routine and official methods).
Honey as a Candidate Reference Material for Trace Elements
Authors: Forte Giovanni , D’Ilio Sonia , Caroli Sergio
Published: February 2020

The feasibility of producing and certifying new certified reference materials (CRMs) for trace elements in honey was investigated. Preliminary steps for preparation of candidate materials are performed at the Institute for Reference Materials and Measurements, Joint Research Centre of the European Commission (EC-JRC-IRMM). Two different types of honey, Acacia and Eucalyptus, were tested for determination of 10 trace elements. To each type of honey was added a given amount of high purity deionized water to obtain aqueous solutions with an acceptable degree of homogeneity which would require only minimal manipulation before analysis. Average values obtained for the trace elements by means of inductively coupled plasma-based techniques were as follows (in μg/kg ± SD): Acacia honey, As, 1.10 ± 0.20; Cd, 0.328 ± 0.035; Cr, 1.90 ± 0.22; Cu, 67.0 ± 5; Fe, 215 ± 30; Hg, < 0.75; Mn, 82.1 ± 6.2; Ni, 21.0 ± 3.0; Pb, 2.30 ± 0.25; Se, 9.10 ± 1.2; Zn, 167 ± 22; Eucalyptus honey, As, 5.99 ± 0.10; Cd, 0.592 ± 0.074; Cr, 1.50 ± 0.07; Cu, 219 ± 24; Fe, 1008 ± 114; Hg, <0.75; Mn, 1009 ± 51; Ni, 11.3 ± 1.5; Pb, 5.00 ± 0.40; Se, 5.60 ± 0.91; Zn, 791 ± 91. When these 2 pilot materials are ready, the certification project will be launched in full compliance with current rules set by EC-JRC-IRMM. If the project is successful, the new CRMs will be put primarily at the disposal of the National Reference Laboratories for trace elements.
Determination of Dissolved Naphthenic Acids in Natural Waters by Using Negative-Ion Electrospray Mass Spectrometry
Authors: Headley John V , Peru Kerry M , Mcmartin Dena W , Winkler Marcus
Published: February 2020

Naphthenic acids (NAs) have been implicated as some of the most toxic substances in oil sands leachates and identified as priority substances impacting on aquatic environments. As a group of compounds, NAs are not well characterized and comprise a large group of saturated aliphatic and alicyclic carboxylic acids found in hydrocarbon deposits (petroleum, oil sands bitumen, and crude oils). Described is an analytical method using negative-ion electrospray ionization mass spectrometry (ES/MS) of extracts. Preconcentration was achieved by using a solid-phase extraction procedure utilizing a crosslinked polystyrene-based polymer with acetonitrile elution. Recovery of the Fluka Chemicals NA mixture was highly pH-dependent, with 100% recovery at pH 3.0, but only 66 and 51% recoveries at pHs 7 and 9, respectively. The dissolved phase of the NA was very dependent on sample pH. It is thus critical to measure the pH and determine the appropriate mass profiles to identify NAs in natural waters. The ES/MS analytical procedure proved to be a fast and sensitive method for the recovery and detection of NAs in natural waters, with a detection limit of 0.01 mg/L.
Gas Chromatographic and Mass Spectrometric Analysis of Nitrilotriacetic Acid in Environmental Aqueous Samples
Authors: Raksit Asit
Published: February 2020

This study describes a fast and accurate method for the sample preparation, identification, and quantitation of nitrilotriacetic (NTA) acid in environmental aqueous samples at a concentration of ppb level. The method is sensitive, specific, and free from the interferences of fatty and amino acids. The tri-n-propyl- and tri-n-butyl-NTA acid esters were prepared by the reaction of n-propyl-HCl and n-butyl-HCl solutions and NTA acid, respectively. The derivatives were analyzed by a gas chromatograph equipped with a mass spectrometric detector. The method detection limit, 0.006 mg/L of each NTA ester, was determined and validated by an analysis of a fortified water sample. The overall recoveries were 103–115%, n = 8. The method was applied to a real sample and a 0.90 mg/L concentration of NTA acid was found. Mass fragmentation patterns of the derivatives are also reported.
Determination of Low-Level Glucose and Fructose in Raw and Refined Crystalline Sugar by High-Performance Anion-Exchange Chromatography: Collaborative Study
Authors: Schäffler Kevin ,   Collaborators:, Bourlet P , Hanko V , Henderson D , Hoebregs H , Maarten de Bruijin J , Morel du Boil P , Nguyen N , Pereira M , Ramphal E , Rearick E , Sural D , van der Waal W , Walford S , Wong L
Published: February 2020

A method was developed and a collaborative study was performed under the auspices of the International Commission of Uniform Methods for Sugar Analysis. The collaborators used high-performance anion-exchange chromatography (HPAEC) to determine trace amounts of glucose and fructose in 3 raw and 3 refined sugar samples provided as blind duplicates. Fourteen laboratories participated in the study. Although difficulties were experienced by a few analysts, 10 laboratories reported positive results. Average repeatabilities and reproducibilities for glucose and fructose in raw sugar were slightly above 5 and 10%, respectively, and the average Horwitz ratios were well under 2. Average repeatabilities and reproducibilities for glucose and fructose in refined sugar were 10 and 22%, respectively; although the Horwitz ratios were >2, they were marginal (2.8). The HPAEC results agreed with results obtained by gas chromatography in an independent laboratory. Because the method was collaboratively studied according to the protocol of the International Union of Pure and Applied Chemistry for collaborative studies, and the results meet its criteria, it is recommended that the method be adopted Official First Action by AOAC INTERNATIONAL.
Determination of Crude Protein in Animal Feed, Forage, Grain, and Oilseeds by Using Block Digestion with a Copper Catalyst and Steam Distillation into Boric Acid: Collaborative Study
Authors: Thiex Nancy J , Manson Harold , Anderson Shirley , Persson Jan-Åke ,   Collaborators:, Anderson S , Bogren E , Bolek G , Budde D , Ellis C , Eriksson S , Field G , Frankenius E , Henderson C , Henry C , Kapphahn M , Lundberg L , Manson H , Moller J , Russell M , Sefert-Schwind J , Spann M
Published: February 2020

A collaborative study was conducted to evaluate the repeatability and reproducibility of an extension of AOAC Official Method 991.20, Nitrogen (Crude) in Milk, to animal feed, forage (plant tissue), grain, and oilseed materials. Test portions are digested in an aluminum block at 420°C in sulfuric acid with potassium sulfate and a copper catalyst. Digests are cooled and diluted, and concentrated sodium hydroxide is added to neutralize the acid and make the digest basic; the liberated ammonia is distilled by using steam distillation. The liberated ammonia is trapped in a weak boric acid solution and titrated with a stronger standardized acid, hydrochloric acid; colorimetric endpoint detection is used. Fourteen blind samples were sent to 13 collaborators in the United States, Denmark, Sweden, Germany, and the United Kingdom. Recoveries of nitrogen from lysine, tryptophan, and acetanilide were 86.8, 98.8, and 100.1%, respectively. The within-laboratory relative standard deviation (RSDr, repeatability) ranged from 0.40 to 2.38% for crude protein. The among-laboratories (including within-) relative standard deviation (RSDR, reproducibility) ranged from 0.44 to 2.38%. It is recommended that the method be adopted First Action by AOAC INTERNATIONAL. A lower concentration (1% H3BO3) of trapping solution was compared with the concentration specified in the original protocol (4% H3BO3) and was found comparable for use in an automatic titration system in which titration begins automatically as soon as distillation starts. The Study Directors recommend that 1% H3BO3 as an optional alternative to 4% boric acid trapping solution be allowed for automatic titrators that titrate throughout the distillation.
Parallux™ β-Lactam: A Capillary-Based Fluorescent Immunoassay for the Determination of Penicillin-G, Ampicillin, Amoxicillin, Cloxacillin, Cephapirin, and Ceftiofur in Bovine Milk
Authors: Huth Stacey P , Warholic Polly S , Devou Jane M , Chaney Larry K , Clark Genevieve H
Published: February 2020

An analytical system was developed for detection of antibiotic residues in bovine milk. The method is based on competitive fluorescent immunoassays in glass capillary tubes (U.S. Patent No. 5,624,850). The system consists of an assay cartridge containing 4 glass capillaries, a reagent tray with 4 wells of dried reagents, and a Parallux™ processor, which processes the assay, reads fluorescent output, and reports test results. Minimum sensitivity for detection of 6 β-lactam antibiotics in bovine milk was determined to be penicillin-G, 3.2 ppb; ampicillin, 2.9 ppb; amoxicillin, 3.6 ppb; cloxacillin, 7.4 ppb; cephapirin, 16.3 ppb; and ceftiofur, 33.7 ppb. The assay system was also specific and sensitive for detection of incurred residues at U.S. Food and Drug Administration tolerance levels: penicillin-G, 5 ppb; ampicillin, 10 ppb; amoxicillin, 10 ppb; cloxacillin, 10 ppb; cephapirin, 20 ppb; and ceftiofur, 50 ppb. There was no interference in detection of minimum sensitivity levels of antibiotic by the presence of somatic cells at approximately 1 × 106 cells/mL. Milk containing 3 × 106 cells/mL bacteria commonly found in mastitic milk also showed no interference when tolerance levels of antibiotic were present. There was no detectable interference on results by a wide variety of non-β-lactam drugs.
Validation of the Hygicult® E Dipslides Method in Surface Hygiene Control: A Nordic Collaborative Study
Authors: Salo Satu , Alanko Timo , Sjöberg Anna-Maija , Wirtanen Gun ,   Collaborators:, Guðbjörnsdóttir B , Jessen B , Langsrud S , Lindquist K , Lundén J , Mäki M , Nerbrink E , Niclasen; Ó , Tuominen P , Tuompo H , Vatunen E , Woivalin A
Published: February 2020

A collaborative study with Enterobacteriaceae was conducted to validate Hygicult® E dipslides by comparison with violet red bile glucose agar (VRBGA) contact plates and swabbing, using stainless steel surfaces artificially contaminated with microbes at various levels. Twelve laboratories participated in the validation procedure. The total number of collaborative samples was 108. The microbial level in each sample was assessed in triplicate by using the 3 above-mentioned methods. No Enterobacteriaceae were used at the low inoculation level. At the middle inoculation level, the percentages detached from the test surfaces were 16.6 with the Hygicult E method, 15.3 with the contact plate method, and 14.6 with swabbing; at the high innoculation level, the percentages were 14.5, 15.8, and 9.8, respectively. The percentage of acceptable results after the removal of outliers was 97.2. Repeatability relative standard deviations ranged from 33.4 to 44.9%; reproducibility relative standard deviations ranged from 45.2 to 77.1%. The Hygicult E dipslide, VRBGA contact plate, and swabbing methods gave similar results at all 3 microbial levels tested: <1.0 colony-forming units (CFU)/cm2 at the low level, 1.2–1.3 CFU/cm2 at the middle level (theoretical yield 8.0 CFU/cm2), and 1.2–2.0 CFU/cm2 at the high level (theoretical yield 12.5 CFU/cm2).
Determination of Nitrite in Foods by Single-Sweep Polarography
Authors: Qiong Li , Tong Zhan , Yong Luo , Dandan Song , Guanghan Lu
Published: February 2020

In an acid medium, nitrite diazotized with p-rosaniline and then coupled with 8-hydroxyquinoline in a weak alkaline medium produces azo compounds. The azo compounds produce a very sensitive polarographic wave at −0.70 V (versus the saturated calomel electrode). The height of the peak is linear with the concentration of nitrite in the range of 5 × 10−9 to 5 × 10−7 g/mL. The detection limit is 3 × 10−9 g/mL. The electrochemical characteristics of the polarographic wave are also discussed. The method was used to determine nitrite in sausage. The results agree well with those obtained by spectrophotometry.
Optimized, One-Step, Recovery-Enrichment Broth for Enhanced Detection of Listeria monocytogenes in Pasteurized Milk and Hot Dogs
Authors: Knabel Stephen J
Published: February 2020

A one-step, recovery-enrichment broth, optimized Penn State University (oPSU) broth, was developed to consistently detect low levels of injured and uninjured Listeria monocytogenes cells in ready-to-eat foods. The oPSU broth contains special selective agents that inhibit growth of background flora without inhibiting recovery of injured Listeria cells. After recovery in the anaerobic section of oPSU broth, Listeria cells migrated to the surface, forming a black zone. This migration separated viable from nonviable cells and the food matrix, thereby reducing inhibitors that prevent detection by molecular methods. The high Listeria-to-background ratio in the black zone resulted in consistent detection of low levels of L. monocytogenes in pasteurized foods by both cultural and molecular methods, and greatly reduced both false-negative and false-positive results. oPSU broth does not require transfer to a secondary enrichment broth, making it less laborious and less subject to external contamination than 2-step enrichment protocols. Addition of 150mM d-serine prevented germination of Bacillus spores, but not the growth of vegetative cells. Replacement of d-serine with 12 mg/L acriflavin inhibited growth of vegetative cells of Bacillus spp. without inhibiting recovery of injured Listeria cells. oPSU broth may allow consistent detection of low levels of injured and uninjured cells of L. monocytogenes in pasteurized foods containing various background microflora.
Determination of Tiamulin in Type C Medicated Swine Feeds Using High Throughput Extraction with Liquid Chromatography
Authors: Moore Douglas B , Britton Nancy L , Smallidge Robert L , Riter Ken L
Published: February 2020

An improved method for extraction and analysis of tiamulin is presented to address issues that arose during routine analysis of Type C medicated swine feeds under the current U.S. Food and Drug Administration-Center for Veterinary Medicine (FDA-CVM) approved method. The issues included the need for higher sample throughput and the ability to accommodate a wider variety of feed matrixes. Changes to the FDA-CVM approved method include reduced sample size and solvent volumes, phosphate buffering of tartaric acid, centrifugation, and use of a new liquid chromatography column and adjusted mobile phase composition. A paired sample study was performed to compare performance of the new and existing methods. The paired sample study showed no statistical difference between sample means of paired sets of 17 samples analyzed by both methods (t = 1.95 at 0.05 significance level, p = 0.068). A recovery study showed the method precision to be 2.06% (coefficient of variation) with an average standard recovery of 95.8%. Ruggedness test results indicated good overall ruggedness of the method.
Comparison of Microbial Receptor Assay and Liquid Chromatography for Determination of Penicillin G and Amoxicillin in Milk Powder
Authors: Anderson Kevin L , Lyman Roberta L , Moats Wlliam A , Hansen Arthur P , Rushing John E
Published: February 2020

A microbial receptor assay (Charm II Tablet Beta-Lactam Test) and liquid chromatography (LC) were compared for determination of penicillin G (PG) and amoxicillin (AMOX) in reconstituted milk powder. Nonfat dry milk and whole dry milk were reconstituted (10%, w/v) to concentrations of 0, 2.5, 5, 7.5, and 10 ppb PG; nonfat dry milk was reconstituted (10%, w/v) to 0, 7.5, 10, and 15 ppb AMOX. Reconstituted samples were analyzed blindly by each method. Concentrations determined by both methods demonstrated good agreement. A significant difference between methods (p ≤ 0.05) was observed only for 7.5 ppb PG in defatted dry milk. Significant differences were not observed between known concentrations and concentrations determined by the Charm II assay for PG or AMOX in defatted dry milk and PG in whole dry milk. Results by LC showed significant differences (p ≤ 0.05) between known and measured concentrations at 10 ppb PG in both milks and 0 ppb AMOX in defatted dry milk. These results suggest that both the microbial receptor assay and LC may be useful for determination of PG and AMOX near safe level and tolerance, respectively, in reconstituted milk powder.
Determination of Niacin in Infant Formula by Solid-Phase Extraction/Liquid Chromatography: Peer-Verified Method Performance–Interlaboratory Validation
Authors: LaCroix Denis E , Wolf Wayne R , Chase G William
Published: February 2020

This paper reports the results of the interlaboratory peer validation study of AOAC Peer-Verified Method (PVM) 1:2000 for the determination of niacin in infant formula by solid-phase extraction/liquid chromatography. We have used a Data Quality Objectives (DQO) approach to address not only method variability and robustness but also accuracy of data through the use of an appropriate reference material in conjunction with the interlaboratory validation study. Our DQO included the following: (1) statistical agreement of analytical results and quantitative recovery between 2 collaborating laboratories; (2) the repeatability relative standard deviation (RSDr) values and the HORRAT (Horwitz ratio) obtained (1.07), which satisfied the criteria of the Horwitz “limits of acceptability” at the analyte level present; (3) validation of lack of interference; and (4) accuracy agreement within assigned values for a certified reference material. National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1846 Infant Formula, with a certified value of 63.3 ± 7.6 μg/g for niacin content, was used as a test material for collaborative study and accuracy assessment. Niacin values obtained by the originating laboratory were 59.7 ± 4.0 μg/g (95% confidence interval [CI] = 1.4 μg/g with a relative standard deviation [RSD] of 6.7%) and by the peer laboratory were 56.6 ± 6.6 μg/g (95% CI = 4.1 μg/g, with an RSD of 11.7%). Statistical evaluation using the means equivalence test showed that nicotinic acid values obtained by the peer laboratory were equivalent to those values obtained by the originating laboratory. Linear calibration curves and quantitative recovery were obtained. Integration of the PVM process with a readily available certified reference material gives the user confidence in the accuracy of the data generated by the method through traceability to the reference material used.
Pesticide Residues in Agricultural Products Monitored in Hyogo Prefecture, Japan, FYs 1995–1999
Authors: Akiyama Yumi , Yoshioka Naoki , Tsuji Masahiko
Published: February 2020

During a 5-year monitoring survey (April 1995–March 2000) of pesticide residues in agricultural products, 765 samples (478 domestic; 287 imported) collected in Hyogo Prefecture, Japan, were analyzed. The number of pesticides tested increased from 107 in fiscal year (FY) 1995 to 204 in FY 1999. The purpose of the study was to promote consumer safety by excluding the food illegally containing pesticide residues from markets. Overall, 51% of domestic and 32% of imported samples contained no detectable residues. Multiple residues were detected in 152 (32%) of domestic and 146 (51%) of imported samples. The limit of quantitation was set at 0.01 μg/g and the limit of detection was 0.001 μg/g. Most of the residues were present at low concentrations; 70% of detections in domestic samples were <0.05 μg/g, and 97% were <0.5 μg/g. Although 86% of antifungal agent residues in imported citrus fruits were ≥ 0.1 μg/g, 59% of the other residues in imported samples were <0.05 μg/g, and 96% were <0.5 μg/g. Violations of maximum residue limits (MRL) were observed in 3 samples: diazinon in chrysanthemums, dieldrin in cucumbers, and bitertanol in bananas. Of the detectable residues above 0.01 μg/g, 55% in domestic and 38% in imported samples were <10% of the MRL. Of all the samples, 2.4% contained more than 5 different pesticides; tomatoes, strawberries, apples, and citrus fruits tended to have more multiple residues.