bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous Analysis of Cadmium, Lead, Mercury, and Arsenic Content in Foodstuffs of Animal Origin by Inductively Coupled Plasma/Mass Spectrometry after Closed Vessel Microwave Digestion: Method Validation
Authors: Noël Laurent , Dufailly Vincent , Lemahieu Nadège , Vastel Christelle , Guérin Thierry
Published: February 2020

A method validation of the total analysis of cadmium (Cd), lead (Pb), arsenic (As), and mercury (Hg) in foodstuffs by inductively coupled plasma/mass spectrometry (ICP/MS) after closed vessel microwave digestion is presented. Due to the lack of reference method for ICP/MS techniques in food and, based on the project of the European Committee of Normalization (CEN/TC 275/WG 10), the Agence Française de Normalisation (AFNOR) guidelines NF V03–110 were used for the evaluation of this method based on 2 steps, sample preparation and multielement detection. Several criteria considered as compulsory (linearity, specificity, precision under repeatability conditions, and trueness) have been estimated and discussed, in addition to intermediate precision reproducibility, the limit of detection, and the limit of quantification. Furthermore, a comparison with in-house methods using electrothermal atomic absorption was performed using an external proficiency testing scheme and food samples. The results indicated that this method could be used in the laboratory for the routine determination of these 4 cumulative toxic metals in foodstuffs with acceptable analytical performance.
Gluten Determination by Gliadin Enzyme-Linked Immunosorbent Assay Kit: Interlaboratory Study
Authors: Gabrovská Dana , Rysová Jana , Filová Vanda , Plicka Jan , Cuhra Petr , KubíK, Martin , BaršOvá Soňa ,   Collaborators:, Bulawová H , Chirdo F G , Dermühl A , Iametti S , Kirinčič S , Pavelka J , Tlaskalová H
Published: February 2020

An interlaboratory study with 10 participants was performed to obtain validation and performance data for an enzyme-linked immunosorbent assay (ELISA) kit developed for quantitative gluten determination in foods. The ELISA kit used for this study is based on 2 monoclonal and 1 polyclonal antibody developed by Immunotech, a Beckman Coulter Co. This kit did not show any false positive results or cross-reactivity with oat, rice, maize, and buckwheat. The gliadin standard from the Working Group on Prolamin Analysis and Toxicity was included in the kit as reference material for calibration. All participants obtained a gliadin ELISA kit with Standard Operational Procedure and a form for recording test results. The study included 13 samples labeled as gluten-free and 2 samples spiked by wheat flour. Seven samples had gliadin content below the limit of quantitation (LOQ) of the method, and 1 sample exceeded the highest calibration level. Gliadin content in the range from 10 to 157 mg/kg (1st day) and from 11 to 183 mg/kg (2nd day) was found in 7 samples (including 2 spiked samples). Results of these samples were used for further statistical analysis and evaluation. The Cochran, Dixon, and Mandel statistical tests were applied for detection of outliers. The LOQ of the kit was estimated.
Testing Deviation for a Set of Serial Dilution Most Probable Numbers from a Poisson-Binomial Model
Authors: Blodgett Robert J
Published: February 2020

A serial dilution experiment estimates the microbial concentration in a broth by inoculating several sets of tubes with various amounts of the broth. The estimation uses the Poisson distribution and the number of tubes in each of these sets that show growth. Several factors, such as interfering microbes, toxins, or disaggregation of adhering microbes, may distort the results of a serial dilution experiment. A mild enough distortion may not raise suspicion with a single outcome. The test introduced here judges whether the entire set of serial dilution outcomes appears unusual. This test forms lists of the possible outcomes. The set of outcomes is declared unusual if any occurrence of an observed outcome is on the first list, or more than one is on the first or second list, etc. A similar test can apply when there are only a finite number of possible outcomes, and each outcome has a calculable probability, and few outcomes have tied probabilities.
Validation of the Antifactor Xa and Antifactor IIa Assays for the Potency Assessment of Nadroparin in Pharmaceutical Formulations
Authors: Dalmora Sérgio Luiz , Sangoi Maximiliano da Silva , Barth Thiago , Brum Liberato , Vaccari Silvana Ferreira
Published: February 2020

The low-molecular weight heparin nadroparin calcium is used clinically for the prevention and treatment of venous and arterial thrombosis. The antifactor Xa and antifactor IIa assays were validated by investigating the parameters of range, linearity (r2 0.9905 and r2 0.9914, respectively) precision, accuracy, and robustness. The 2 methods incorporated a chromogenic endpoint and detection at 405 nm, yielding good results with detection limits of 0.004 and 0.01 IU/mL and quantitation limits of 0.01 and 0.03 IU/mL, respectively, for the antifactor Xa and antifactor IIa assays. Nadroparin calcium pharmaceutical products were evaluated by the antifactor Xa assay and the antifactor IIa assay, giving potencies between 93.86 and 109.88%, with an antifactor Xa/antifactor IIa ratio between 3.2 and 3.7. The results demonstrated the validity of the assays that are useful methodologies for the routine quality control of nadroparin in pharmaceutical formulations.
Determination of Nifedipine in Serum ofWomen in Preterm Labor by High-Performance Liquid Chromatography with Diode Array Detection
Authors: Kowalczuk Dorota , Wawrzycka Maria Bożena , Maj Agnieszka Haratym
Published: February 2020

Nifedipine (Nif) is widely used in treating cardiovascular disorders (especially hypertension) and for inhibiting preterm labor. A fully validated selective high-performance liquid chromatographic method with diode array detection, using solid-phase extraction, was developed for the determination of Nif in human serum. To assess specificity, Nif and its degradation products were separated on a Purospher RP-18 (5m, 125×4 mm) column plus a LiChrospher 100 RP-18 (5 μm, 4×4 mm) precolumn with a mobile phase of methanol10 mM aqueous trifluoroacetic acid, pH 7.3 (57 + 43, v/v); chromatographic separation was followed by UV detection at 238 nm. For toxicological analysis, Nif in the presence of other calcium-channel antagonist drugs was identified under optimum chromatographic conditions. The calibration graph was constructed over the concentration range of 12.5400 ng/mL in serum with good correlation (r 0.9956). This method was not subject to interference by other plasma components and was successfully applied to the assay of Nif in spiked human serum and in serum of women in preterm labor after sublingual administration of 30 mg Nif per day divided into 3 equal doses. The mean recovery based on the ratio of the slopes of serum and mobile phase standard curves was 96.5%. The detection and quantification limits of the drug in spiked human serum were found to be 6 and 17.5 ng/mL, respectively. Validation of the method demonstrated good intraday and interday precision, which ranged from 2.18 to 6.67% and from 6.52 to 11.93%, respectively.
Determination of Four Nitroimidazoles in Poultry and Swine Muscle and Eggs by Liquid Chromatography/Tandem Mass Spectrometry
Authors: Xia Xi , Li Xiaowei , Shen Jianzhong , Zhang Suxia , Ding Shuangyang , Jiang Haiyang
Published: February 2020

A rapid method is presented for the determination of 4 nitroimidazoles in poultry and swine muscle and eggs by liquid chromatographyelectrospray ionizationtandem mass spectrometry (LCESIMSMS). Samples were extracted with acetonitrile, then evaporated the organic phase. After filtration, the extract was directly injected into the LCESIMSMS system. The LC separation was made on a C8 column by applying a gradient composed of water and acetonitrile. Overall average recoveries ranged from 5086 for egg, 66115 for poultry muscle, and 79111 for swine muscle. The decision limits ranged from 0.05-0.25 μgkg for egg, 0.07-0.27 μgkg for poultry muscle, and 0.07-0.26 μgkg for swine muscle; and detection capabilities ranged from 0.510.68 gkg for egg, 0.41-0.75 μgkg for poultry muscle, and 0.53-0.78 μgkg for swine muscle.
Determination of Chloramphenicol Residue in Chicken Tissues by Immunoaffinity Chromatography Cleanup and Gas Chromatography with aMicrocell Electron Capture Detector
Authors: Zhang Suxia , Zhou Jinhui , Shen Jianzhong , Ding Shuangyang , Li Jiancheng
Published: February 2020

A rapid and sensitive gas chromatography (GC) method was developed to detect chloramphenicol in chicken tissues. The extracted samples were cleaned up using the immunoaffinity column prepared by coupling antichloramphenicol monoclonal antibody with cyanogen bromide-activated Sepharose 4B. The dynamic column capacity of chloramphenicol was 3265 ng/mL gel. The eluate was evaporated to dryness, and residues were derivatized and determined by GC with a microcell electron capture detector. Average recoveries were 86.6 to 96.9 for chicken muscle and 74.3 to 96.1 for chicken liver. The limit of quantitation of the method was 0.05 ng/g for chicken muscle and 0.1 ng/g for chicken liver.
Predicting Aflatoxin and Fumonisin in Shelled Corn Lots Using Poor-Quality Grade Components
Authors: Johansson Anders S , Whitaker Thomas B , Hagler Winston M , Bowman Daryl T , Slate Andy B , Payne Gary
Published: February 2020

A study was conducted to determine if aflatoxin and fumonisin are concentrated in the poor-quality grade components of shelled corn. Four 1.0 kg test samples were each taken from 23 lots of shelled corn marketed in North Carolina. Inspectors from the Federal Grain Inspection Service divided each test sample into 3 grade components: (1) damaged kernels (DM), (2) broken corn and foreign material (BCFM), and )3) whole kernels (WH). The aflatoxin and fumonisin concentration was measured in each component and a mass balance equation was used to calculate the total concentration of each mycotoxin in each test sample. Averaged across all test samples, the aflatoxin concentrations in the DM, BCFM, and WH components were 1300.3, 455.2, and 37.3 ppb, respectively. Averaged across all test samples, the fumonisin concentrations in the DM, BCFM, and WH components were 148.3, 51.3, and 1.8 ppm, respectively. The DM and BCFM components combined accounted for only 5.0% of the test sample mass, but accounted for 59.8 and 77.5% of the total aflatoxin and fumonisin mass in the test sample, respectively. Both aflatoxin mass (ng) and aflatoxin concentration (ng/g) in the combined DM and BCFM components had high correlations with aflatoxin concentration in the lot. The highest correlation occurred when aflatoxin mass (ng) in the combined DM and BCFM components was related to aflatoxin concentration in the lot (0.964). Similar results were obtained for fumonisin. This study indicated that measuring either aflatoxin or fumonisin in the combined DM and BCFM grade components could be used as a screening method to predict either aflatoxin or fumonisin in a bulk lot of shelled corn.
Determination of Aflatoxin B1 in Medical Herbs: Interlaboratory Study
Authors: Arranz Isabel , Sizoo Eric , Van Egmond Hans , Kroeger Katy , Legarda Teresa M , Burdaspal Pedro , Reif Klaus , Stroka Joerg
Published: February 2020

A method was developed for the determination of aflatoxin B1 in medical herbs (senna pods, botanical name Cassia angustifolia; devil's claw, botanical name Harpagophytum procumbens; and ginger roots, botanical name Zingiber officinale). The method, which was tested in a mini-collaborative study by 4 laboratories, is based on an immunoaffinity cleanup followed by reversed-phase high-performance liquid chromatography separation and fluorescence detection after post-column derivatization. It allows the quantitation of aflatoxin B1 at levels lower than 2 ng/g. A second extractant (acetonewater) was tested and compared to the proposed methanolwater extractant. Several post-column derivatization options (electrochemically generated bromine, photochemical reaction, and chemical bromination) as well as different integration modes (height versus area) were also investigated. No differences were found depending on the choice of derivatization system or the signal integration mode used. The method was tested for 3 different matrixes: senna pods, ginger root, and devil's claw. Performance characteristics were established from the results of the study and resulted in HorRat values ranging from 0.12 to 0.75 with mean recoveries from 78 to 91% for the extraction with methanolwater and HorRat values ranging from 0.101.03 with mean recoveries from 98 to 103% for the extraction with acetonewater. As a result, the method, with all tested variations, was found to be fit-for-purpose for the determination of aflatoxin B1 in medical herbs at levels of 1 g/kg and above.
Biosensor Analysis of β-Lactams in Milk Using the Carboxypeptidase Activity of a Bacterial Penicillin Binding Protein
Authors: SternesjÖ Åse , Gustavsson Eva
Published: February 2020

The applicability of a -lactam receptor protein for detection of β-lactam antibiotics in milk using surface plasmon resonance (SPR) biosensor technology was investigated. The advantage of using a receptor protein instead of antibodies for detection of β-lactams is that a generic assay, specific for the active form of the β-lactam structure, is obtained. Two assays based on the enzymatic activity of the dd-carboxypeptidase from Actinomadura R39 were developed, using a Biacore SPR biosensor. The carboxypeptidase converts a tri-peptide into a di-peptide, a reaction which is inhibited in the presence of β-lactams. Polyclonal antibodies against the 2 peptides were developed and used to measure the amount of enzymatic product formed (di-peptide assay) or the amount of remaining enzymatic substrate (tri-peptide assay), respectively. The 2 assays showed similar performances with respect to detection limits (1.2 and 1.5 μg/kg, respectively) and precision (coefficient of variation <5%) for penicillin G in milk. Several other β-lactams were detected at or near their respective maximum residue limit. Furthermore, the 2 peptide assays were evaluated against 5 commercial kit tests in the screening of 195 producer milk samples. The biosensor assays showed 0% false-negative and 27% false-positive results, whereas the figures were 0% false-negative and 2753% false-positive results for other screening tests investigated.
Determination of the 1,3- and 2-Positional Distribution of Fatty Acids in Olive Oil Triacylglycerols by 13C Nuclear Magnetic Resonance Spectroscopy
Authors: Vlahov Giovanna
Published: February 2020

Linear models were selected from a large data set acquired for Italian olive oil samples by quantitative 13C nuclear magnetic resonance (NMR) spectroscopy with distortionless enhancement by polarization transfer (DEPT). The models were used to determine the composition of the 2 fatty acid pools esterifying the 1,3- and 2-positions of triacylglycerols. The linear models selected proved that the 1,3- and 2-distribution of saturated, oleate, and linoleate chains in olive oil triacylglycerols deviated from the random distribution pattern to an extent that depended on the concentration of the fatty acid in the whole triacylglycerol. To calculate the fatty acid composition of the 1,3- and 2-positions of olive oil triacylglycerols, the equations of the selected linear models were applied to the fatty acid percentages determined by gas chromatography. These data were compared with the values predicted by the computer method (used to determine the theoretical amounts of triacylglycerols), which is based on the 1,3-random-2-random theory of the fatty acid distribution in triacylglycerols. The biggest differences were found in the linoleate chain, which is the chain that deviated the most from a random distribution pattern. The results confirmed that the 1,3-random-2-random distribution theory provides an approximate method for determining the structure of triacylglycerols; however, the linear models calculated by the direct method that applies 13C NMR spectroscopy represent a more precise measurement of the composition of the 2 fatty acid pools esterifying the 1,3- and 2-positions of triacylglycerols.
Microbiological Assay for Lomefloxacin in Coated Tablets
Authors: Gomes Greici Cristiani , Salgado Hérida Regina Nunes
Published: February 2020

The validation of a microbiological assay, applying cylinder plate method for determination of the activity of lomefloxacin in coated tablets is described. Using a strain of Bacillus subtilis ATCC 9372 as the test organism, lomefloxacin was measured in concentrations ranging from 2.0 to 8.0 μg/mL. The method validation showed that it is linear (r = 0.9999), precise (relative standard deviation = 1.15%), and accurate (it measured the added quantities). The excipients did not interfere in the determination. It was concluded that the microbiological assay is satisfactory for quantitation of lomefloxacin in tablets.
A Highly Sensitive Spectrofluorometric Method for the Determination of a New Antidepressant Drug, Reboxetine, in Tablets
Authors: Önal ArmaĞan
Published: February 2020

A highly sensitive, selective, and rapid spectrofluorometric method has been developed for the determination of reboxetine (REB) in tablets. The method is based on derivatization with 7-chloro-4-nitrobenzofurazan. The product showed an absorption maximum at 476 nm and a fluorescence emission peak at 533 nm in ethyl acetate. The optimum conditions of the reaction were investigated, and it was found that the reaction proceeded quantitatively at pH 8.5, 70C in 5 min. The calibration graph is rectilinear over the range of 0.02-0.40 μg/mL. The relative standard deviation values for intraday and interday precision were 0.40-0.93 and 0.54-1.37%, respectively. The proposed method was applied to the assay of REB in tablets. Mean recovery of REB from the tablets ranged between 99.91-100.20%. The results were compared statistically with those obtained by a method reported in the literature. The method is sensitive, simple, and selective, and can be used for routine quality control analysis.
Modification to the AOAC Sporicidal Activity of Disinfectants Test (Method 966.04): Collaborative Study
Authors: Tomasino Stephen F , Hamilton Martin A , Garza H Chan A ,   Collaborators:, Buen M , Chan Myers H , Garza A , Gonzales E , Kallander K , Rodriguez A , Stahnke P , To T
Published: February 2020

In an effort to improve AOAC Method 966.04, the Sporicidal Activity of Disinfectants Test, selected modifications to the procedure were evaluated in a collaborative study. Method 966.04 is used to generate efficacy data to support the product registration of sporicides and sterilants. The method is a carrier-based test that provides a qualitative measure of product efficacy against spores of Bacillus subtilis and Clostridium sporogenes. The use of garden soil extract and the lack of standard procedures for the enumeration of spores and neutralization of the test chemicals have been considered problematic for many years. The proposed modifications were limited to the B. subtilis and hard surface carrier (porcelain penicylinder) components of the method. The study included the evaluation of a replacement for soil extract nutrient broth and an establishment of a minimum spore titer per carrier, both considered crucial for the improvement and utilization of the method. Additionally, an alternative hard surface material and a neutralization confirmation procedure were evaluated. To determine the equivalence of the proposed alternatives to the standard method, 3 medium/carrier combinations, (1) soil extract nutrient broth/porcelain carrier (current method), (2) nutrient agar amended with 5 g/mL manganese sulfate/porcelain carrier, and (3) nutrient agar amended with 5 g/mL manganese sulfate/stainless steel carrier were analyzed for carrier counts, HCl resistance, efficacy, quantitative efficacy, and spore wash-off. The test chemicals used in the study represent 3 chemical classes and are commercially available antimicrobial liquid products: sodium hypochlorite (bleach), glutaraldehyde, and a combination of peracetic acid and hydrogen peroxide. Four laboratories participated in the study. The results of the spore titer per carrier, HCl resistance, efficacy, and wash-off studies demonstrate that amended nutrient agar in conjunction with the porcelain is comparable to the current method, soil extract nutrient broth/porcelain. The nutrient agar method is simple, inexpensive, reproducible, and provides an ample supply of high quality spores. Due to the current use of porcelain carriers for testing C. sporogenes, it is advisable to retain the use of porcelain carriers until stainless steel can be evaluated as a replacement carrier material for Clostridium. The evaluation of stainless steel for Clostridium has been initiated by the Study Director. Study Director recommendations for First Action revisions are provided in a modified method.
Determination of Benzimidazole Fungicides in Soil Samples Using Microwave-Assisted Micellar Extraction and Liquid Chromatography with Fluorescence Detection
Authors: Halko Radoslav , Sanz Carolina PadrÓn , Ferrera Zoraida Sosa , RodrÍguez JosÉ Juan Santana
Published: February 2020

A simple and fast analytical method was developed for the determination of benzimidazole fungicides (benomyl, carbendazim, thiabendazole, and fuberidazole) in soil samples. The analytes were extracted from the soil samples by means of conventional microwave-assisted extraction, using the non-ionic surfactants polyoxyethylene 10 lauryl ether (POLE) and oligoethylene glycol monooalkyl ether (Genapol X-080) as extractants. Determinations were made by using liquid chromatography with direct fluorescence detection. The use of an analytical column Symmetry C-18 offered short retention times of analytes without the need of any pH regulators with mobile phase methanolwater (50 + 50, v/v). The best results were obtained using 5% (v/v) POLE as extractant with recoveries of the fungicides in spiked soil samples between 71 and 105%. The results were compared with those obtained when Soxhlet extraction was applied to the same soil samples.
Determination of Eight Synthetic Pyrethroids in Bovine Fat by Gas Chromatography with Electron Capture Detection
Authors: Akre Christine J , MacNeil James D
Published: February 2020

Synthetic pyrethroids are among the most widely used classes of insecticides, and their uses are varied, including plant protection, animal dips, and as a treatment for human clothing and bedding in very hot climates. Veterinary applications include ear tags, pour-on formulations, sprays, and dips. Persistent residues have been reported in livestock, and routine monitoring programs in other countries have found detectable residues of various pyrethroids in fat. A method has been developed using solid-phase extraction that reduces the quantities of solvents used, the time required, and the amount of glassware used compared to an earlier method on which it was based. The scope of analytes tested included the 5 compounds cited in the earlier method (flucythrinate, permethrin, cypermethrin, fenvalerate, and deltamethrin) and, in addition, cyfluthrin, λ-cyhalothrin, and fluvalinate. Sample extracts were analyzed by gas chromatography with electron capture detection using selected chromatographic peaks characteristic of each compound. Limits of quantification for the compounds were from 25-50 μg/kg, with a linear response for all compounds to 200 μg/kg. Recoveries ranged from 80 to 123%.
Validation of a Liquid Chromatographic Method for Determination of Tacrolimus in Pharmaceutical Dosage Forms
Authors: Moyano MarÍa A , Simionato Laura D , Pizzorno Mara T , Segall Adriana I
Published: February 2020

An accurate, simple, and reproducible liquid chromatographic method was developed and validated for the determination of tacrolimus in capsules. The analysis is performed at room temperature on a reversed-phase C18 column with UV detection at 210 nm. The mobile phase is methanolwater (90 10) at a constant flow rate of 0.8 mL/min. The method was validated in terms of linearity, precision, accuracy, and specificity by forced decomposition of tacrolimus, using acid, base, water, hydrogen peroxide, heat, and light. The response was linear in the range of 0.090.24 mg/mL (r2 0.9997). The relative standard deviation values for intra- and interday precision studies were 1.28 and 2.91%, respectively. Recoveries ranged from 98.06 to 102.52%.
Feasibility Study for the Production of Certified Calibrants for the Determination of Deoxynivalenol and Other B-Trichothecenes: Intercomparison Study
Authors: Krska Rudolf , Welzig Elvira , Drs Elisabeth , Josephs Ralf D , Schothorst Ronald C , Egmond Hans P Van , Pettersson Hans , Chan Danny , MacDonald Susan
Published: February 2020

Thirteen European laboratories experienced in the analysis of mycotoxins participated in an intercomparison study within a European Commission-funded project. Goals of the study were to check the fitness for purpose of a small batch of gravimetrically prepared calibrants; to compare individually prepared calibrants with common calibrants; to check the feasibility of toxin mixtures as calibrant solutions; and to give recommendations on the production of future certified reference materials (CRMs) with regard to the nature of the calibrant and the means of certification. Each laboratory received ampules of each common calibrant containing single toxins [solution containing either deoxynivalenol (DON), 3-acetyl-DON (3-Ac-DON), nivalenol (NIV), or 15-acetyl-DON (15-Ac-DON)] and 3 ampules of toxinmixture (solutions of DON 3-Ac-DON NIV in acetonitrile) of known concentrations (about 20 g/mL). Ampules with single toxins (solution containing either DON, 3-Ac-DON, NIV, or 15-Ac-DON) and a toxinmixture (solutions of DON 3-Ac-DON NIV in acetonitrile) of unknown concentrations were distributed to the participants for quantification. The participating laboratories used mainly high-performance liquid chromatography (HPLC)diode array detection UV for DON, 3-Ac-DON, NIV, and 15-Ac-DON; gas chromatography-electron capture detection (GC-ECD) and GC-mass spectrometry methods were used sparingly. Linear calibration curves were achieved by >90% of the participants. Relative between-day variation (RSDr) of 26% of the laboratories was greater than the target value of 5% for HPLC, and RSDr of 32% of the laboratories was greater than the desired value of 10% for GC. Relative between-laboratory variation (RSDR) of the GC results obtained with single common calibrants was greater than the target value of 16% for all laboratories. RSDR of the HPLC results for the common unknown single toxin solutions was less than the target value of 8% except for 15-Ac-DON. Generally, better recoveries were observed from common calibrants (102% for mix calibrants and 98% for single calibrants) than from individually prepared calibrants (95%). This international comparison study clearly showed the high scattering of results in the analysis of type-B trichothecenes, particularly when GC was used. Obviously, this intercomparison study was not suited for the certification of B-trichothecenes. A certification of the proposed calibrant material was therefore recommended on the basis of its gravimetrical preparation.
A Novel Correlation for Rapid Lactose Determination in Milk by a Cryoscopic Technique
Authors: Colinas Carmen , Barrera Ignacio , Blanco Carlos A
Published: February 2020

Residual lactose in special milk was systematically determined for people with lactose intolerance by means of a rapid on-line measurement of the cryoscopic point. A proposed cryoscopic procedure was compared to 2 conventional yet highly laborious methods: the enzymatic procedure with spectrophotometric control and the polarimetric method. Several experiments with different mixtures of both semi-skimmed and low-lactose milk were performed. A lineal relationship was found between lactose concentration and freezing point, the analytical equation for which shows a close relationship regarding the 3 methods used. The advantages of the cryoscopic procedure include speed in obtaining results and operational simplicity at a low cost, better monitoring of enzymatic hydrolysis kinetics, and greater control over the production process for delactosed milk. The equation obtained also enables prediction of the lactose percentage in commercial milk by a simple measurement of freezing point.
Quantitative Assessment of Hard Surface Disinfectant Activity Against the Foodborne Pathogen Listeria monocytogenes
Authors: Arnold Judy W , DeLaubenfels Eric , Zambelli-Weiner April
Published: February 2020

Listeria monocytogenes is an important foodborne pathogen that must be controlled to ensure food safety. For the years 2003 and 2004, L. monocytogenes caused 20 deaths per 100 listeriosis cases and was responsible for most food recalls for pathogen contamination. The objective of this work was to develop a quantitative method to assess disinfectant activity against L. monocytogenes. Standard procedures for testing disinfectants against 3 bacteria are described in the AOAC Official Methods of Analysis as use-dilution methods. No standard methods are provided for L. monocytogenes. In this study, preliminary efficacy of a quaternary ammonium compound with hydroperoxide ion was determined for 25 bacterial strains. The zones of inhibition ranged from 7.0 to 12.5 mm, and the minimum inhibitory concentration ranged from 5 to 250 ppm. For final efficacy, stainless steel carriers were contaminated with L. monocytogenes and tested separately for 5, 10, and 15 min in disinfectant or phenol. After exposure, the carriers were placed into 2 series of D/E neutralization broth. For 3 replications with duplicate samples, the phenol coefficient was 3.3. This research presents a technique-sensitive method that provides quantitative data for comparison and analysis of disinfectant activity against L. monocytogenes.
On Determining a 1-Tailed Upper Limit for Future Sample HorRat Values
Authors: McClure Foster D , Lee Jung K
Published: February 2020

Two formulas were developed for use in computing 1-tailed upper limits for future HorRat values obtained from the collaborative study of materials. One formula is applicable when a future sample HorRat value    is computed based on a known concentration (e.g., C spike level and RSDR is the sample relative reproducibility standard deviation) and the other formula is applicable when the true concentration (C) is unknown and a future sample HorRat value    is computed using the sample mean (e.g.,   , the collaborative study overall mean for an analyte). A Monte Carlo simulation procedure was developed using the Statistical Analysis System (SAS) software to assess the accuracy of the 2 developed formulas. Based on the degree of closeness between the simulated and calculated limits, the formulas for computing upper limits for future sample HorRat values will prove to be useful to Study Directors in determining worst case scenarios concerning a method's reproducibility precision relative to that predicted using the Horwitz equation. We also define the current empirical HorRat limits as 1-tailed 100p% upper limits to assess the statistical consequence, in a probability sense, of their application as an analytical methods screening tool.
Quantitative Estimation of Parthenolide in Tanacetum parthenium (L.) Schultz-Bip. Cultivated in Egypt
Authors: El-Shamy Ali M , El-Hawary Seham S , Rateb Mostafa E M
Published: February 2020

Parthenolide, a germacranolide-type sesquiterpene lactone, was estimated in Tanacetum parthenium (L.) cultivated in Egypt by using colorimetric, planar chromatographic, and high-performance liquid chromatographic (HPLC) methods. Parthenolide levels in the open-field herb and aseptically germinated shoots were also compared by using the HPLC method. Parthenolide was produced and estimated for the first time in the callus culture of the plant. In addition, 2 Egyptian market preparations were analyzed for their parthenolide content by using the HPLC method. The relative standard deviations were 0.093, 0.095, and 0.098% (n = 5,5,and 7, respectively), and the corresponding recoveries were 98.2, 98.9, and 99.4% for the colorimetric, planar chromatographic, and HPLC determinations, respectively.
A Novel Method for Determination of Protein in Human Serum Utilizing the Trihydroxylphenylfluorone-Molybdenum(VI) Complex as a Probe by Fluorescence Spectrometry
Authors: Wei Qin , Ma Hongmin , Duan Caihong , Wang Jin , Liu Shuyuan , Du Bin
Published: February 2020

The fluorescence intensity of the trihydroxylphenylfluorone-molybdenum(VI) Mo(VI) complex is quenched by protein. Based on this, a novel method for protein assay in aqueous solution was developed. With pH 3.75 acetic acidsodium acetate buffer solution, in the presence of p-octyl polyethylene glycol phenyl ether microemulsion, the quenched fluorescence intensity is proportional to the concentration of bovine serum albumin (BSA) in the range of 07.00 μg/mL, and the detection limit of BSA is 5.65 ng/mL. There is no interference from amino acids and most metal ions. The method developed in this paper has been used for the successful determination of protein in human serum.
Pesticide Residue Analysis of Vegetables by Gas Chromatography with Electron-Capture Detection
Authors: Fenoll José , Hellín Pilar , Martínez Carmen M , Flores Pilar
Published: February 2020

A new and original analytical method was developed for the routine analysis of 28 multiclass pesticide residues in vegetables (green pepper, red pepper, and tomato). The extraction was performed with acetone, and the pesticides were partitioned into ethyl acetatecyclohexane (1 + 1, v/v). Residue levels in vegetables were determined by gas chromatography (GC) with electron-capture detection. Residue identities were confirmed by GC coupled with mass spectrometry in the selected ion monitoring mode. The average recoveries in pepper and tomato obtained for all analytes studied were 67.3 and 123.1%, respectively, with relative standard deviation between 1.8 and 7.0%. The detection limit for the pesticides studied varied from 0.1 to 2.6 μg/kg. The proposed method was applied to the analysis of these compounds in vegetables grown in experimental greenhouses.
Determination of Inorganic Arsenic(III) and Arsenic(V) in Water Samples by Ion Chromatography/Inductively Coupled Plasma-Mass Spectrometry
Authors: Yip Yiu-Chung , Chu Hei-Shing , Yuen Chung-Fai , Sham Wing-Cheong
Published: February 2020

A method was validated for the direct determination of As(III) and As(V) in water samples by ion chromatography/inductively coupled plasma-mass spectrometry. Sample preservation required only dilution with a mobile phase containing a sufficient amount of ethylenediaminetetraacetic acid and acetic acid. Analyses of 6 certified reference materials (CRMs) of various water matrixes, including seawater, demonstrated good method accuracy. The matrixes included 2 natural water samples National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1643e and NIST SRM 1640, 1 fortified standard solution (TMDA-64), 1 fortified water sample (TM-DWS), and 2 seawater samples (CASS-4 and NASS-5). The sum of As(III) and As(V) in each CRM agreed with the respective certified value for the total amount of As within its stated uncertainty. Quantitative recoveries (96.7-102.1%) were obtained. Satisfactory results were achieved for intraday repeatability relative standard deviation (RSD 0.3-5.1%] and interday precision (RSD 0.7-4.1%). In the study of fortified blanks and fortified CRMs, quantitative recoveries of As(III) and As(V) (92.5-102.6%) were obtained. Interconversion of As(III) and As(V) was not observed under the conditions of sample preservation. International comparability of analytical results was demonstrated by the analysis of 2 interlaboratory proficiency test samples, NY7011 and NY8511, from the New York State Department of Health.
Determination of Synephrine in Bitter Orange Raw Materials, Extracts, and Dietary Supplements by Liquid Chromatography with Ultraviolet Detection: Single-Laboratory Validation
Authors: Roman Mark C , Betz Joseph M , Hildreth Jana
Published: February 2020

A method has been developed to quantify synephrine in bitter orange raw material, extracts, and dietary supplements. Single-laboratory validation has been performed on the method to determine the repeatability, accuracy, selectivity, limit of detection/limit of quantification (LOQ), ruggedness, and linearity for p-synephrine and 5 other biogenic amines: octopamine, phenylephrine (m-synephrine), tyramine, N-methyltyramine, and hordenine, which may be present in bitter orange. p-Synephrine was found to be the primary biogenic amine present in all materials tested, accounting for >80 of the total biogenic amine content in all samples except a finished product. Repeatability precision for synephrine was between 1.48 and 3.55 RSD. Synephrine recovery was between 97.5 and 104. The minor alkaloids were typically near the LOQ of the method (300900 g/g) in the test materials, and between-day precision for the minor compounds was poor because interferences could sometimes be mistakenly identified as one of the minor analytes. Recoveries of the minor components ranged from 99.1 to 103 at approximately 6000 g/g spike level, to 90.7 to 120 at 300 g/g spike level.
Relative Stability of Selenites and Selenates in Feed Premixes as a Function of Water Activity
Authors: Eisenberg Sylvan
Published: February 2020

Sodium selenite is more hygroscopic than sodium selenate. It is, therefore, more likely to dissolve when dispersed in feeds of relatively high water activity. When dissolved, it may form selenious acid and disperse as a vapor. This is easily demonstrated by mounting a filter paper wetted with a reagent such as ascorbic acid over the subject feed, but not in contact with it. The paper turns brown as elemental selenium is formed from reduction of the vapor. Analysis of the paper ensures that the brown is indeed selenium. Though premixes are generally low enough in moisture content to ensure stability of the selenites, this is not true of many feeds. The water activities of a number of feeds, feed premixes, and feed ingredients have been determined instrumentally and compared to those of saturated solutions of sodium selenite and sodium selenate. There is no question that the selenite often dissolves with the potential to react and, in so doing, loses its nutritional function.
Validation of RAPID' Staph for Enumeration of Staphylococcus aureus in Foods
Authors: Lauer Wendy F , Gary Sandrine M T , Patel Asmita
Published: February 2020

RAPID' Staph (Bio-Rad Laboratories, Hercules, CA) is a medium for differentiation and enumeration of coagulase-positive Staphylococcus aureus in food. RAPID'Staph medium is based on a Baird Parker formula optimized for the detection and enumeration of S. aureus in 24 h. The principle of the medium relies on the capacity of S. aureus to reduce tellurite (production of black colonies) and to provoke proteolysis of egg yolk (production of clear halo around the colony). Four foods (pasteurized whole milk, custard pie, processed ham, and smoked salmon) were selected to compare the performance of RAPID' Staph agar to AOAC Official Method 975.55. Method comparison studies demonstrated excellent agreement between the methods. Inclusivity and exclusivity rates of the medium were 100%. RAPID' Staph agar performed as expected when minor procedural variations were introduced, validating the ruggedness of the method. There was no difference in performance between the dehydrated and ready-to-use formulations of the media.
Improved Determination of Isolated trans Isomers in Edible Oils by Fourier Transform Infrared Spectroscopy Using Spectral Reconstitution
Authors: de Voort Frederik R van , Sedman Jacqueline , Hussain Sherazi Syed Tufail
Published: February 2020

A substantially more sensitive and accurate alternative to the single-bounce attenuated total reflectance (SB-ATR) Fourier transform infrared spectroscopic method of AOAC/American Oil Chemists' Society (AOCS) was developed for determination of isolated trans isomers, based on transmission measurements using a technique called spectral reconstitution (SR). The method involves the 1:1.5 dilution of an oil with odorless mineral spirits (OMS) containing a spectralmarker. The resulting reduction in sample viscosity facilitates the use of a transmission flow cell, with the spectralmarker serving to determine the precise dilution ratio. This allows the spectral contributions of the OMS to be eliminated and a facsimile of the neat oil spectrum to be mathematically reconstituted. The transmission- SR (T-SR) procedure was initially evaluated relative to SB-ATR to track changes in the trans content of mixtures of unhydrogenated canola and a highly hydrogenated sunflower oil (030% trans). The results indicated that the T-SR procedure had the potential to serve as the basis of an accurate quantitative method. A subsequent T-SR calibration based on the spectral ratioing principle of the SB-ATR AOAC/AOCSmethod was developed by gravimetrically adding trielaidin (04%) to extra virgin olive oil (EVO), producing an excellent linear response with a standard deviation (SD) of <0.04% trans. Subsequent comparison of SB-ATR and T-SR calibrations developed for 5 oils of different types, each spiked with low levels of trielaidin (01.2% trans), clearly indicated that SB-ATR was signal-limited, whereas the T-SR procedure performed well. The EVO calibration was subsequently used to predict the added trans content of these spiked oils, after the spectrum of the corresponding unspiked oil had been ratioed out. The resulting plot of predicted versus added trans was linear, with a slope of 1.02 and an overall SD of <0.05% trans. When the spectra of these oils were ratioed against the spectrum of EVO, the trans predictions for some of the oils were offset by 23 percentage points, emphasizing the need for the appropriate trans-free reference oil to perform accurate analyses. If the latter condition is met, then T-SR provides a very simple technique, with the potential for automation, for analysis of oils by transmission spectroscopy, with approximately 20 the sensitivity of the AOAC/AOCS SB-ATR method.
Determination of Tianeptine in Tablets by High-Performance Liquid Chromatography with Fluorescence Detection
Authors: Ulu Sevgi Tatar
Published: February 2020

A sensitive and selective high-performance liquid chromatographic method has been developed for the determination of tianeptine (Tia) in tablets. The method is based on derivatization of Tia with 4-chloro-7-nitrobenzofurazan (NBD-Cl). A mobile phase consisting of acetonitrile10 mM orthophosphoric acid (pH 2.5; 77 + 23) was used at a flow rate of 1 mL/min on a C18 column. The Tia-NBD derivative was monitored using a fluorescence detector, with emission set at 520 nm and excitation at 458 nm. Gabapentin was selected as an internal standard. Linear calibration graphs were obtained in the concentration range of 45300 ng/mL. The lower limit of detection (LOD) was 10 ng/mL at a signal-to-noise ratio of 4. The lower limit of quantitation (LOQ) was 45 ng/mL. The relative standard values for intra- and interday precision were <0.46 and <0.57%, respectively. The recovery of the drug samples ranged between 98.89 and 99.85%. No chromatographic interference from the tablet excipients was found. The proposed method was validated in terms of precision, robustness, recovery, LOD, and LOQ. All the validation parameters were within the acceptance range. The proposed method was applied for the determination of Tia in commercially available tablets. The results were compared with those obtained by an ultraviolet spectrophotometric method using t- and F-tests.
Determination of Methylcellulose and Hydroxypropyl Methylcellulose Food Gums in Food and Food Products: Collaborative Study
Authors: Harfmann Robert G , Deshmukh Balasaheb K , Conklin Jerry , Turowski Maciej , Lynch Stephanie ,   Collaborators:, Butler B H , Chiu M , Cittadino J , Kotvas M , Kuriyedath R , Larson B , Nabak J , Okot-Kotber M , Post B , Reif K , Shen H , Spence W B , Thomsen A , Valley K , Villoria M , Zielinski J
Published: February 2020

A collaborative study was performed to determine the reproducibility of a method for the determination of methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) in food. These widely used food gums possess unusual solubility characteristics and cannot accurately be determined by existing dietary fiber methods. The new method uses the enzyme-digestion procedure of AOAC Official Method 991.43. Digestate solutions must be refrigerated to fully hydrate MC or HPMC. The chilled solutions are filtered and analyzed by size-exclusion liquid chromatography. Collaborating laboratories received 28 samples containing MC or HPMC in the range of 0100%. The sample set included blind duplicates of 5 food matrixes (bread, milk, fish, potato, and powdered juice drink). Cochran and Grubbs tests were used to eliminate outliers. For food samples containing MC, values for within-laboratory precision, repeatability relative standard deviation (RSDr), ranged from 4.2 to 16%, and values for among-laboratories precision, reproducibility relative standard deviation (RSDR), ranged from 11 to 20%. For HPMC samples, RSDr values ranged from 6.4 to 27%, and RSDR values ranged from 17 to 39%. Recoveries of MC and HPMC from the food matrixes ranged from 78 to 101%. These results show acceptable precision and reproducibility for the determination of MC and HPMC, for which no Official AOAC Methods exist. It is recommended that this method be adopted as AOAC Official First Action.
Determining the Variability Associated with Testing Shelled Corn for Aflatoxin Using Different Analytical Procedures in Louisiana in 1998
Authors: Park Douglas L , Whitaker Thomas B , Simonson Janet , Morris Hershel F , Durr Bobby , Njapau Henry
Published: February 2020

The number of elevator facilities with laboratories to test shelled corn for aflatoxin on site is increasing. The inherent difficulty in accurately determining the true aflatoxin concentration of a lot of corn may have serious implications. Deviations from the true value are of even greater significance at busy locations where a high throughput is desired. This study was instituted to measure (1) the differences in aflatoxin test results between elevator laboratories and the Louisiana Agricultural Chemistry (LAC) laboratory and (2) the variability in aflatoxin test results associated with sampling, sample preparation, and analysis of shelled corn at such locations. One hundred lots of shelled corn from 10 elevators in Louisiana were analyzed for aflatoxin using the Aflatest method (at elevators and at the LAC laboratory) and high-performance column liquid chromatography (HPLC; LAC laboratory only). Mean aflatoxin levels determined at elevator laboratories were significantly (P < 0.05) lower from those obtained in the LAC laboratory using the Aflatest method. Overall, Aflatest method results were lower than those obtained by HPLC. This difference may be attributed to analyst technical dexterity, difficulty in providing careful attention to detail in a high throughput environment, and/or substandard facilities found at elevators. The total variance was partitioned into the combined sampling plus subsampling variance and analytical variance. The sampling and sample preparation steps accounted for about 91.5% of the total variability. When using the HPLC analytical method, the analytical step contributed only 8.5% to the total variance.