bluuebunny/crossref_metadata_2025 huggingface dataset:
Two Rapid Methods for Detection of Escherichia coli Exceeding 104/g Action Levels: Precollaborative Study
Authors: Grant Michael A , Wernberg Jane S , Van Khanh T , Albert Angelina M
Published: February 2020

The current AOAC Method 966.24 for enumeration of Escherichia coli in foods uses a most probable number (MPN) procedure with extensive confirmation steps. Two new methods based on membrane filtration (MF) were compared to the MPN reference method for detection of high levels of E. coli in 5 food types, some of which represent categories for which the U.S. Food and Drug Administration (FDA) mandates additional testing if an action level of 104/g E. coli is exceeded. Ground beef, which is not FDA regulated, was also tested. The 5 food types were all inoculated at 3 levels: 102/g, ≥104/g, and ≥105/g E. coli. An MF protocol using either m-ColiBlue24® (CB) or lauryl sulfate tryptose plus BCIG (LST/BCIG) was an effective potential alternative to the reference method. Sensitivity and specificity for both CB and LST/BCIG were 98 and 100%, respectively. Agreement between MPN and both CB and LST/BCIG was 98%. The 2 proposed methods allow completion of both presumptive and confirmatory steps in 13 days, whereas the reference method requires as many as 11 days. Exclusivity testing with 50 non-E. coli strains indicated 100% were correctly ruled out by the proposed protocols. Inclusivity testing was used to determine whether typical results were obtained after incubation of E. coli cultures on CB or LST/BCIG for 24 h. Of 50 E. coli strains tested, 100% yielded typical results after incubation on CB, and 98% yielded typical results after incubation on LST/BCIG.
Determination of Arsenic, Cadmium, Cobalt, Chromium, Lead, Molybdenum, Nickel, and Selenium in Fertilizers by Microwave Digestion and Inductively Coupled Plasma-Optical Emission Spectrometry Detection: Collaborative Study
Authors: Kane Peter F , Hall William L ,   Collaborators:, Bartos J , Boles R , Dupuis M , Hasty E , Kinsey C , Mullins S , Newlon N , Purkiss J , Rivera C , Robarge W , Sakyi-Amfo K , Seeley C , Seigel S , Svee M , Van Erem T , Vindiola A
Published: February 2020

There is increasing regulatory interest in the non-nutritive metals content of fertilizer materials, but at present there is no consensus analytical method for acid digestion and instrument detection of those elements in fertilizer matrixes. This lack of method standardization has resulted in unacceptable variability of results between fertilizer laboratories performing metals analysis. A method has been developed using microwave digestion with nitric acid at 200C, followed by inductively coupled plasma-optical emission spectrometry instrument detection, for the elements arsenic, cadmium, cobalt, chromium, molybdenum, nickel, lead, and selenium. The method has been collaboratively studied, and statistical results are here reported. Fourteen collaborators were sent 62 sample materials in a blind duplicate design. Materials represented a broad cross section of fertilizer types, including phosphateore, manufactured phosphate products, N-P-K blends, organic fertilizers, and micro-nutrient materials. As much as possible within the limit of the number of samples, materials were selected from different regions of the United States and the world. Limit of detection (LOD) was determined using synthetic fertilizers consisting of reagent grade chemicals with near zero levels of the non-nutritive elements, analyzed blindly. Samples with high iron content caused the most variability between laboratories. Most samples reasonably above LOD gave HorRat values within the range 0.5 to 2.0, indicating acceptable method performance according to AOAC guidelines for analyses in the mg/kg range. The method is recommended for AOAC Official First Action status.
A Validated Liquid Chromatographic Method for Estimation of Solasodine in Various Solanum Species and Market Formulations
Authors: Trivedi Priti D , Patel Brijesh C , Rathnam Shivprakash , Pundarikakshudu Kilambi
Published: February 2020

This paper describes an improved liquid chromatographic (LC) method involving a prechromatographic derivatization step for the estimation of solasodine from berries of various Solanum species, market samples of Solanum xanthocarpum herb, extract, and its market formulations. Solasodine has heterocyclic nitrogen but has no conjugated double bonds in its structure. However, in all reported LC methods, detection was made in the ultraviolet range of 200213 nm. In the present study, a prechromatographic derivatization of solasodine was done by forming an ion-pair complex of the heterocyclic nitrogen using the acidic dye methyl orange and acetate buffer of pH 4.7. Detection could be made in the visible range at 530 nm in this method. The method was validated and successfully applied to determine solasodine content in various plant samples and polyherbal formulations. The relative standard deviation was found to be 0.025% for system precision, and 0.8% for the linearity of the method, and the correlation coefficient was 0.999. Plant samples and market formulations were analyzed and found to contain solasodine in the range of 0.1130.227% (w/w) on a fresh weight basis in berries; 0.31.278% (w/w) and 0.412% (w/w) on a dry weight basis in S. xanthocarpum herb powder and extract, respectively; and 0.2450.525% (w/w) on dry weight basis in formulations containing S. xanthocarpum herb powder. No matrix interference was encountered. The method was found to be accurate, with a mean recovery of 100.5 ±0.83%. The method has good reproducibility and was found to be suitable for estimation of solasodine.
Fractional Wavelet Analysis for the Simultaneous Quantitative Analysis of Lacidipine and Its Photodegradation Product by Continuous Wavelet Transform and Multilinear Regression Calibration
Authors: Din Erdal , Ragno Gaetano , Ioele Giuseppina , Baleanu Dumitru
Published: February 2020

Fractional wavelet transform (FWT) was applied to the original absorption spectra of lacidipine (LAC) and its photodegradation product (LACD), and the resulting FWT spectra were processed by continuous wavelet transform (CWT) and multilinear regression calibration (MLRC) for the simultaneous quantitative analysis of both products in their binary mixtures. These methods do not require any chemical separation step and chemical complex reaction to obtain a detectable signal for the degradation product. By using the Mexican hat function, 2 calibration functions for LAC and LACD were obtained by measuring the CWT transformed signals at 416.1 nm for LAC and 414.6 nm for LACD, after FWT processing of the original absorption spectra. The calibration graphs were linear in the concentration range of 5.0840.64 μg/mL for LAC and 0.518.16 μg/mL for LACD. The limit of detection and the limit of quantitation were found to be 0.289 and 0.956 μg/mL for LAC and 0.036 and 0.118 μg/mL for LACD, respectively. For comparison, the MLRC algorithm was applied to the linear regression functions for the individual drug and its photoproduct. In this approach, a set of linear regression functions was obtained from the relationship between concentrations and FWT signals in the wavelength range 411.0412.4 nm. Both methods were applied to the quantitative evaluation of LAC and LACD in laboratory and pharmaceutical samples, and produced very satisfactory results.
Simultaneous Determination of Hyoscine Butylbromide and Ketoprofen in Pharmaceutical Preparations by Spectrophotometric and Liquid Chromatographic Methods
Authors: El-Saharty Yasser Shaker , Metwally Fadia H , Refaat Mohamed , El-Khateeb Sonia Zaki
Published: February 2020

A binary mixture of hyoscine butylbromide and ketoprofen was determined by 4 different methods. The first involved determination of hyoscine butylbromide and ketoprofen using the ratio-spectra first-derivative spectrophotometric technique at 211 and 234 nm over the concentration ranges of 2-14 and 5-45 μg/mL with mean accuracies 99.84 ± 0.92 and 99.98 ± 0.64%, respectively. The second method utilized second-derivative spectrophotometry over the concentration ranges of 2-14 and 5-35 μg/mL with mean accuracies 99.32 ± 1.06 and 99.55 ± 1.15%, respectively. The third method was based on the resolution of the 2 components by bivariate calibration depending on a simple and rapid mathematical algorithm and quantitative evaluation of the absorbances at 206 and 254 nm over concentration ranges of 2-16 and 5-35 μg/mL; mean accuracies of 100.21 ± 1.30 and 100.19 ± 1.07% were obtained for hyoscine butylbromide and ketoprofen, respectively. The fourth method was reversed-phase liquid chromatography using 0.05 M ammonium dihydrogen phosphateacetonitrilemethanol (20 + 30 + 6, v/v) as the mobile phase with ultraviolet detection at 220 nm over concentration ranges of 1-90 and 5-70 μg/mL; mean accuracies were 99.92 ± 1.02 and 99.61 ± 0.98%, respectively. The suggested procedures were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical preparations. The methods retained their accuracy and precision when the standard addition technique was applied. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by the manufacturer's method.
Determination of Patulin in Apple and Hawthorn Beverages by Solid-Phase Filtration Column and Liquid Chromatography
Authors: Li Fengqin , Zhao Shan , Chin Leejiuan , Li Yuwei , Wu Duojia , Zhao Xi , Han Chunhui , Zhang Hongyuan , Ji Rong
Published: February 2020

The use of solid-phase filtration column (MycoSep 228®) and liquid chromatography for determination of patulin in apple and hawthorn beverages was investigated. The method passed a series of validation tests, including separation efficiency, sensitivity, repeatability, validation within a collaborative trial, recoveries, and applicability. Accuracy and precision were very good for determination of patulin in both spiked and naturally contaminated apple/hawthorn beverage samples at levels of 10 μg/L and above, with limits of detection and quantification at 8 and 23 μg/L, respectively. The applicability of the method was tested by analyzing commercially available domestic apple and hawthorn beverages. Patulin was found in 3 of 52 (5.77%) apple beverages at concentrations ranging from 63.45 to 88.44 μg/L, and in 6 of 43 (13.95%) hawthorn beverages ranging from 19.8 to 206.88 μg/L. Among these were 3 apple and 4 hawthorn beverage samples with toxin levels that exceeded the Chinese legislative requirement of 50 μg/L in apple- and hawthorn-based products intended for human consumption. Comparable tests revealed that the results obtained by both the new MycoSep-based method and the official AOAC method are not significantly different (t value 0.003268 < t0.05, P > 0.05).
Determination of Site-Specific (Deuterium/Hydrogen) Ratios in Vanillin by 2H-NuclearMagnetic Resonance Spectrometry: Collaborative Study
Authors: Jamin Eric , Martin Frédérique , Martin Gilles G ,   Collaborators:, Billault I , Blanch-Cortès A -I , Fauhl C , Guillou C , Ha S , Hermann A , Lamoureux C , Mazac J , Rétif M
Published: February 2020

The results of collaborative study are reported for a method that determines the site-specific isotope ratios of deuterium/hydrogen (D/H)i in vanillin by deuterium-nuclear magnetic resonance (2H-NMR) spectrometry. This method allows characterization of all the main commercial sources of commercial vanillin and detection of undeclared mixtures. It is based on the fact that the amounts of deuterium at various positions in the vanillin molecule are significantly different from one source to another. Vanillin is dissolved in acetonitrile and analyzed with a high-field NMR spectrometer fitted with a deuterium probe and a fluorine lock. The proportions of isotopomers monodeuterated at each hydrogen position of the molecule are recorded, and the corresponding (D/H) ratios are determined by using a calibrated reference. Nine laboratories analyzed 5 materials supplied as blind duplicates (1 natural vanillin from vanilla beans, 2 synthetic vanillins from guaiacol, 1 semisynthetic vanillin from lignin, and a mixture of natural and synthetic vanillins). The precision of the method for measuring site-specific ratios was as follows: for (D/H)1 the within-laboratory standard deviation (sr) values ranged from 2.2 to 5.8 ppm, and the among-laboratories standard deviation (sR) values ranged from 3.6 to 5.1 ppm; for (D/H)3 the sr values ranged from 1.7 to 3.2 ppm, and the sR values ranged from 2.4 to 3.7 ppm; for (D/H)4 the sr values ranged from 2.3 to 6.2 ppm, and the sR values ranged from 2.4 to 6.4 ppm; for (D/H)5 the sr values ranged from 0.8 to 2.7 ppm, and the sR values ranged from 0.9 to 2.3 ppm. It was shown that these values allow a satisfactory discrimination between vanillin sources. Therefore, the Study Director recommends the method for adoption as a First Action Official Method by AOAC INTERNATIONAL.
Quantitative Recovery of Listeria monocytogenes and Select Salmonella Serotypes from Environmental Sample Media
Authors: Bazaco Michael C , Eifert Joseph D , Williams Robert C , Kathariou Sophia
Published: February 2020

Environmental sampling has become increasingly important in the food industry for monitoring the presence of specific pathogens such as Listeria monocytogenes and Salmonella enterica. Several microbiological media are available for storage and transport of environmental samples from the processing plant to the test laboratory. In this study, we quantified the survival of L. monocytogenes, S. Typhimurium, S. Enteritidis, and S. Typhi in environmental sampling media over several time and temperature combinations to determine optimum conditions for transport and storage. A cocktail of L. monocytogenes strains and Salmonella serotypes was separately added to tubes of Dey-Engley (D/E) Neutralizing Broth, Copan SRK solution, and Neutralizing Buffer and incubated at either -4, 4, 10, or 15°C. Counts were made of the bacterial load after 0, 12, 24, and 48 h. Neutralizing Buffer and Copan SRK solution were best at maintaining bacterial concentrations at all temperatures. D/E Neutralizing Broth, at 10 and 15C, allowed significant bacterial growth. This study helped validate the use of these 3 media for environmental sample transport and storage at cold holding temperatures and demonstrated that, at elevated temperatures (>4°C), it is preferable to use Neutralizing Buffer or Copan SRK solution for quantifying microbial recovery.
Simultaneous Determination of Paracetamol, Chlorzoxazone, and Related Impurities 4-Aminophenol, 4'-Chloroacetanilide, and p-Chlorophenol in Pharmaceutical Preparations by High-Performance Liquid Chromatography
Authors: Ali Mohammed Shahid , Rafiuddin Syed , Ghori Mohsin , Kahtri Aamer Roshanali
Published: February 2020

This paper presents a simple, specific, and precise high-performance liquid chromatographic method for the simultaneous determination of paracetamol (PCM), chlorzoxazone (CXZ), and their related impurities in bulk raw materials and solid dosage forms. The mobile phase consisted of water methanolglacial acetic acid (60 + 40 2, v/v/v). A column containing octadecylsilane chemically bonded to porous silica particles (Spherisorb ODS 1, 25 cm × 4.6 mm, 5 μm) was used as stationary phase. Detection was performed using a variable wavelength ultraviolet-visible detector set at 272 nm for all compounds. Solutions were injected into the chromatograph under isocratic condition at a constant flow rate of 1.2 mL/min. The method was validated according to International Conference on Harmonization requirements and demonstrates good accuracy and precision and a wide linearity range. The method separates PCM, CXZ, and 3 major impurities 4-aminophenol (4AP), 4'-chloracetanilide (4CA), and p-chlorophenol (PCP) with fair resolution in less than 15 min. The developed method is rapid and sensitive (limit of detection for 4AP, 4CA, and PCP established at 31.25, 39.06, and 65.16 ng/mL, respectively) and, therefore, suitable for quality control and stability studies of these compounds in dosage forms.
Fast Cleanup Method for the Analysis of Sudan IIV and Para Red in Various Foods and Paprika Color (Oleoresin) by High-Performance Liquid Chromatography/Diode Array Detection: Focus on Removal of Fat and Oil as Fatty Acid Methyl Esters Prepared by Transesterification of Acylglycerols
Authors: Uematsu Yoko , Ogimoto Mami , Kabashima Junichirou , Suzuki Kumi , Ito Kouichi
Published: February 2020

A fast and effective cleanup method was developed for the analysis of Sudan I, II, III, IV, and Para Red (Sudan dyes) in various foods and paprika color (oleoresin) by high-performance liquid chromatography (LC) with a diode array detector (DAD). Removal of fat or oil in fatty sample was a critical point for reducing the volume of the final sample solution in order to obtain a sufficient level of the analytes. Separation of fat or oil from the dyes with a silica gel solid-phase extraction (SPE) column seemed unfeasible, because elution profiles of oil, fat, and the dyes were similar. Finally, fat and oil were separated from the dyes by elution from the SPE column with n-hexane, not as intact compounds but as fatty acid methyl esters prepared by direct transesterification of acylglycerols in fat and oil, leaving the dyes on the column. The dyes were eluted with n-hexanediethyl ether (9 + 1). Gradient elution with water and tetrahydrofuran was used for separation on a C18 column by LC. Measurement of spectral of μ0.5 g/g of Sudan dyes in foods and 1 μg/g in paprika color (oleoresin) with the DAD was achieved.
Determination of Low-Level Agricultural Residues in Soft Drinks and Sports Drinks by Gas Chromatography with Mass-Selective Detection: Single-Laboratory Validation
Authors: Paske Nathan , Berry Bryan , Schmitz John , Sullivan Darryl
Published: February 2020

In this study, sponsored by PepsiCo Inc., a method was validated for measurement of 19 pesticide residues in soft drinks and sports drinks by gas chromatography/mass spectrometry (GC/MS) with mass selective detection The pesticide residues determined in this validation were -benzenehexachloride (BHC); -BHC; -BHC; delta-BHC; methyl parathion; malathion; chlorpyrifos; aldrin; 2,4-dichlorodiphenyldichloroethylene (DDE); -endosulfan; 4,4-DDE; 2,4-dichlorodiphenyldichloroethane (DDD); dieldrin; ethion; 4,4-DDD; 2,4-dichlorodiphenyltrichloroethylene (DDT); -endosulfan; 4,4-DDT; and endosulfan sulfate when spiked into a 200 mL matrix sample at 0.50 g/L. The samples were diluted with acetonitrile and water, then liquidliquid phase extracted into petroleum ether. The resulting extract was concentrated to near dryness and diluted with hexane:dichloromethane (50:50). The concentrated samples were purified by gel permeation chromatography. The resulting solution was concentrated and separated on a Florisil substrate. The eluent was concentrated to near dryness, reconstituted to produce a 200-fold concentration, and analyzed using a GC/MS instrument operated in the selective ion monitoring mode. The GC/MS instrument was equipped with a large volume injector capable of injecting 25 L. External standards prepared in dichloromethane were used for quantification without the need for matrix-matched calibration because the extraction step minimized the matrix effects. The calibration curves for all agricultural residues had coefficients of determination (r2) of greater than or equal to 0.9900, with the exception of one value that was 0.988. Fortification spikes at 0.50 g/L in 3 matrixes (7UP, Gatorade, and Diet Pepsi) over the course of 2 days (4 days for Gatorade), where n = 8 each day, yielded average percent recoveries (and percent relative standard deviations) as follows (n = 64): 95.6 (24.8) for -BHC; 91.9 (23.6) for -BHC; 89.1 (21.3) for - BHC; 91.7 (19.0) for -BHC; 96.2 (20.1) for methylparathion; 99.8 (26.5) for malathion; 120 (27.3) for chlorpyrifos; 103 (31.4) for aldrin; 111 (25.8) for 2,4-DDE; 116 (21.1) for -endosulfan; 132 (34.6) for 4,4-DDE; 123 (34.4) for 2,4-DDD; 104 (20.8) for dieldrin; 141 (31.4) for ethion; 107 (24.5) for 4,4-DDD; 142 (29.2) for 2,4-DDT; 130 (35.9) for -endosulfan; 146 (25.3) for 4,4-DDT; and 91.5 (21.6) for endosulfansulfate.
Determination of Pesticides in Apples by Liquid Chromatography with Electrospray Ionization Tandem Mass Spectrometry and Estimation of Measurement Uncertainty
Authors: Wang Jian , Wotherspoon David
Published: February 2020

A liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) method was developed and validated to determine 90 pesticides in apple samples. MS/MS data acquisition was achieved by applying multiple-reaction monitoring of 2 fragment ion transitions to provide a high degree of sensitivity and selectivity for both quantitation and confirmation. Matrix-matched standard calibration curves with the use of isotopically labeled standards (or a chemical analog) as internal standards were used to achieve the best accuracy for the method. Both a conventional method validation procedure and a designed experiment were applied to study the accuracy and precision of the method. A compiled computer program that provided a semiautomated procedure for handling a large number of calculations was used to calculate the overall recovery, intermediate precision, and measurement uncertainty (MU). In general, the overall recoveries from samples spiked at levels of 10, 50, and 80 g/kg, ranged from 60.8 to 121.1%, intermediate precision was <10%, and MUs were <30%. Poor accuracy and/or repeatability was observed for pyridate and etofenprox. The method limits of detection based on a signal-to-noise ratio of >3 were usually <1 g/kg (ppb), except those for aldicarb sulfoxide and pyridaphenthion, which were about 5 g/kg.
On Using an Approximate Noncentral t-Distribution in Determining a One-Side Upper Limit for Future Sample Relative Reproducibility Standard Deviations
Authors: McClure Foster D , Lee Jung K
Published: February 2020

For future sample relative reproducibility standard deviations (RSDR), collaboratively obtained under a completely randomized model (CRM), a new formula for determining a one-tailed 100p% upper limit (p) for such RSDR values was developed based on an approximate noncentral t-distribution with degrees of freedom obtained using Satterthwaite's adjustment. The accuracy of p was assessed by comparing p and its probability levels with similar values associated with a Monte Carlo simulation and with those obtained using another formula (p) that was developed for the same purpose but based on a normal approximation.
Determination of Chondroitin Sulfate Content in Raw Materials and Dietary Supplements by High-Performance Liquid Chromatography with Ultraviolet Detection After Enzymatic Hydrolysis: Single-Laboratory Validation
Authors: Ji David , Roman Mark , Zhou Joseph , Hildreth Jana
Published: February 2020

A method to quantify chondroitin sulfate in raw materials and dietary supplements at a range of about 5 to 100% (w/w) chondroitin sulfate has been developed and validated. The chondroitin sulfate is first selectively hydrolyzed by chondroitinase ACII enzyme to form un-, mono-, di-, and trisulfated unsaturated disaccharides; the resulting disaccharides are then quantified by ion-pairing liquid chromatography with ultraviolet detection. The amounts of the individual disaccharides are summed to yield the total amount of chondroitin sulfate in the material. Single-laboratory validation has been performed to determine the repeatability, accuracy, selectivity, limit of detection, limit of quantification, ruggedness, and linearity of the method. Repeatability precision for total chondroitin sulfate content was between 1.60 and 4.72% relative standard deviation, with HorRat values between 0.79 and 2.25. Chondroitin sulfate recovery from raw material negative control was between 101 and 102%, and recovery from finished product negative control was between 105 and 106%.
Determination of Campesterol, Stigmasterol, and Beta-Sitosterol in Saw Palmetto Raw Materials and Dietary Supplements by Gas Chromatography: Collaborative Study
Authors: Sorenson Wendy R , Sullivan Darryl ,   Collaborators:, Baugh S , Collison M , Das R , Erickson A , Harmon T , Heathman S , Ji D , Khandelwal B , Kohn A , Morris S , Norden D , Peng T , Post B , Powers E , Reif K , Schulzki G , Shevchuk C , Solyom A
Published: February 2020

An interlaboratory study was conducted to evaluate a method for the determination of campesterol, stigmasterol, and beta-sitosterol in saw palmetto raw materials and dietary supplements at levels >1.00 mg/100 g based on a 23 g sample. Test samples were saponified at high temperature with ethanolic KOH solution. The unsaponifiable fraction containing phytosterols (campesterol, stigmasterol, and beta-sitosterol) was extracted with toluene. Phytosterols were derivatized to trimethylsilyl ethers and then quantified by gas chromatography with hydrogen flame ionization detection. Twelve blind duplicates, one of which was fortified, were successfully analyzed by 10 collaborators. Recoveries were obtained for the sample that was fortified. The results were 99.8, 111, and 111% for campesterol, stigmasterol, and beta-sitosterol, respectively. For repeatability, the relative standard deviation (RSDr) ranged from 3.93 to 17.3% for campesterol, 3.56 to 22.7% for stigmasterol, and 3.70 to 43.9% for beta-sitosterol. For reproducibility, the RSDR ranged from 7.97 to 22.6%, 0 to 26.7%, and 5.27 to 43.9% for campesterol, stigmasterol, and beta-sitosterol, respectively. Overall, the Study Director approved 5 materials with acceptable HorRat values for campesterol, stigmasterol, and beta-sitosterol ranging from 1.02 to 2.16.
Evaluation of the GeneQuence® DNA Hybridization Method in Conjunction with 24-Hour Enrichment Protocols for Detection of Salmonella spp. in Select Foods: Collaborative Study
Authors: Mozola Mark A , Peng Xuan , Wendorf Michael ,   Collaborators:, Alles S , Artiga L , Buchholz T , Camacho A , Charveron N , Clayborn J , Decker C , Deibel C , Donohue T , Draughon A , Ewings J , Feldworth M , Gane P , Goodwin J , Gunter T , Gutierrez M , Hovland R , Jechorek R , Jones W , Keskinen L , Lamproe B , Larson E , Manwarren H , Merkling A , Osing C , Pangloli P , Remes A , Richter E , Rogers A , Rose B , Ryser E , Secraw S , Slupik M , Wessinger A , Westmoreland R , Yan Z , Zahoor T , Zhang L
Published: February 2020

A multilaboratory study was conducted to compare performance of the GeneQuence® DNA hybridization (DNAH) method incorporating new 24 h enrichment protocols and reference culture procedures for detection of Salmonella spp. in select foods. Six food types (raw ground turkey, raw ground beef, dried whole egg, milk chocolate, walnuts, and dry pet food) were tested by the DNAH method and by the culture methods of either the U.S. Department of Agriculture-Food Safety and Inspection Service (USDA-FSIS) or the U.S. Food and Drug Administration's Bacteriological Analytical Manual (FDA/BAM). Fifteen laboratories participated in the study. Four of the foods tested (raw ground turkey, dried whole egg, milk chocolate, and dry pet food), showed no statistically significant differences in performance between the DNAH method and the reference procedure as determined by Chi square analysis. Sensitivity rates for the DNAH method ranged from 92 to 100. The DNAH method, with the specific enrichment protocol evaluated, was found to be ineffective for detection of Salmonella spp. in walnuts. For raw ground beef, results from one trial showed a statistically significant difference in performance, with more positives obtained by the reference method. However, evidence suggests that the difference in the number of positives was likely due to lack of homogeneity of the test samples rather than to DNAH method performance.
Immunoaffinity Column Cleanup with Liquid Chromatography for Determination of Aflatoxin B1 in Corn Samples: Interlaboratory Study
Authors: Brera Carlo , Debegnach Francesca , Minardi Valentina , Pannunzi Elena , Santis Barbara De , Miraglia Marina ,   Collaborators:, Bergamini C , Biancardi A , Bodda M , Bonassisa L , Burdaspal P , Cantamessa L , Chessa G , Commissati I , Corrao A , Dömsödi J , Esposito G , Focardi C , Garbini D , Gatti M , Gibellino C , Kroeger K , Lombardi F M , Mambelli P , Mastrantoni J , Michelet J Y , Møller T , Pascale M , Petrini C , Pietri A , Piombino M , Piro R , Pittet A , Rizzi N , Stroka J , Thim A M , Ubaldi A , Villani A , Zanon F
Published: February 2020

An interlaboratory study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for the determination of aflatoxin B1 levels in corn samples, enforced by European Union legislation. A test portion was extracted with methanolwater (80 + 20); the extract was filtered, diluted with phosphate-buffered saline solution, filtered on a microfiber glass filter, and applied to an immunoaffinity column. The column was washed with deionized water to remove interfering compounds, and the purified aflatoxin B1 was eluted with methanol. Aflatoxin B1 was separated and determined by reversed-phase LC with fluorescence detection after either pre- or postcolumn derivatization. Precolumn derivatization was achieved by generating the trifluoroacetic acid derivative, used by 8 laboratories. The postcolumn derivatization was achieved either with pyridinium hydrobromide perbromide, used by 16 laboratories, or with an electrochemical cell by the addition of bromide to the mobile phase, used by 5 laboratories. The derivatization techniques used were not significantly different when compared by the Student's t-test; the method was statistically evaluated for all the laboratories. Five corn sample materials, both spiked and naturally contaminated, were sent to 29 laboratories (22 Italian and 7 European). Test portions were spiked with aflatoxin B1 at levels of 2.00 and 5.00 ng/g. The mean values for recovery were 82% for the low level and 84% for the high contamination level. Based on results for spiked samples (blind pairs at 2 levels) as well as naturally contaminated samples (blind pairs at 3 levels), the values for relative standard deviation for repeatability (RSDr) ranged from 9.9 to 28.7%. The values for relative standard deviation for reproducibility (RSDR) ranged from 18.6 to 36.8%. The method demonstrated acceptable within- and between-laboratory precision for this matrix, as evidenced by the HorRat values.
Discriminatory Power, Typability, and Accuracy of Single Nucleotide Extension Microarrays
Authors: Berget Ingunn , Heir Even , Petcovic Jelena , Rudi Knut
Published: February 2020

Despite great conceptual promise, the use of microarrays in typing approaches has not yet gained wide acceptance. The establishment of proper criteria for determining discriminatory power as well as typability and the accuracy of microarray data remains to be solved. Purely experimental estimations of these parameters would far exceed what is experimentally practical. We therefore used simulations in combination with experimental results in parameter estimations. Our assay was based on 26 single nucleotide polymorphisms (SNPs) identified in the Campylobacter jejuni Multi Locus Sequence Typing (MLST) database (http://pubmlst.org/campylobacter/). The SNPs were detected using a single nucleotide extension (SNE) typing microarray. Unknown isolates were assigned to the known sequence type(s) by calculating weighted sum of matches minus a weighted sum of mismatches between predicted and candidate genotype. The weights were set according to the Bayesian posterior probability of the SNP classification. These studies showed that any typing or profiling method based on binary data requires an accuracy of <23% error for each datapoint (in our case SNPs) to classify the isolates to the correct allelic profile in 90% of the cases. The classification error for our experimental data was 3.2% (after removing 5 high error SNPs). We therefore conclude that SNE microarrays are promising for future high-throughput typing of bacteria.
Application of a Quantitative Carrier Test to Evaluate Microbicides against Mycobacteria
Authors: Springthorpe V Susan , Sattar Syed A
Published: February 2020

Microbicides for reprocessing heat-sensitive medical devices, such as flexible endoscopes, must be mycobactericidal to reduce the risk of nosocomial infections. Suspension test methods currently used for efficacy evaluation lack the stringency required for assessing inactivation of mycobacteria on surfaces. The quantitative carrier test method reported here is based on mycobacteria-contaminated reference carrier disks of brushed stainless steel. Each disk was contaminated with 10 L of a suspension of Mycobacterium terrae containing a soil load. Each disk with a dried inoculum was placed in a glass or Teflon vial, and then overlaid with 50 L of the test formulation or 50 L saline for the control carriers. Five test and 3 control disks were used in each run. At the end of the contact time, each vial received 9.95 mL neutralizer solution with 0.1% Tween-80 to stop the reaction and perform the initial microbicide dilution. The inoculum was eluted by mixing on a Vortex mixer for 60 s, and the eluates and saline used to subsequently wash the vials and the funnels were membrane-filtered. Filters were placed on plates of Middlebrook 7H11 agar and incubated at 37C for at least 30 days before colonies were counted and log10 reductions were calculated in colony-forming units. Tests with a range of commercially available products, having claims against mycobacteria, or believed to be broad-spectrum microbicides, showed that the method gave reproducible results. Products used included oxidizing agents (sodium hypochlorite and an iodophore), a phenolic, a quaternary ammonium compound, and ortho-phthalaldehyde. This method represents a much more realistic evaluation than the currently used quantitative suspension test method for the evaluation of mycobactericidal formulations for registration and, when performed at different product concentrations, allows an assessment of any safety margin or risks in using the test formulation in the field.
A Method for Determination of Selenium in Organic Tissues Using Microwave Digestion and Liquid Chromatography
Authors: Govasmark Espen , Grimmett Mark G
Published: February 2020

An existing laboratory procedure for selenium analysis using open-vessel wet digestion and liquid chromatographic fluorescence determination was modified for use with microwave digestion. The proposed microwave digestion method eliminated the hazards associated with the use of HCIO4 while maintaining excellent recoveries of selenium. A 2-step HNO3/H2O2 digestion procedure was developed. Digested samples were derivatized with 2,3-diaminonaphthalene, and the resultant piazselenol complex was measured fluorometrically using a liquid chromatograph. Measured values were in agreement with 9 different certified reference materials. The detection limit for this method was 0.54 ng Se/g tissue (3 ), and the calibration curve remained linear (r2 = 0.9968) up to 2 g Se/g.
Determination of Arsenic, Cadmium, Mercury, and Lead by Inductively Coupled Plasma/Mass Spectrometry in Foods after Pressure Digestion: NMKL Interlaboratory Study
Authors: Julshamn Kaare , Maage Amund , Norli Hilde Skaar , Grobecker Karl H , Jorhem Lars , Fecher Peter ,   Collaborators:, Hentschel A , Martin de la Hinojosa I , Viehweger L , Mindak W R , Lindholm K , Holm K , Olsson B , Engman J , Habernegg R , Hammer D , Lewis J , van der Wielen J , Hovind H , Vadset M
Published: February 2020

Thirteen laboratories participated in an interlaboratory method performance (collaborative) study on a method for the determination of arsenic, cadmium, mercury, and lead by inductively coupled plasma/mass spectrometry (ICP/MS) after pressure digestion including the microwave heating technique. Prior to the study, the laboratories were able to practice on samples with defined element levels (pretrial test). The method was tested on a total of 7 foodstuffs: carrot puree, fish muscle, mushroom, graham flour, simulated diet, scampi, and mussel powder. The elemental concentrations in mg/kg dry matter (dm) ranged from 0.0621.4 for As, 0.0328.3 for Cd, 0.040.6 for Hg, and 0.012.4 for Pb. The materials used in the study were presented to the participants as blind duplicates, and the participants were asked to perform single determinations on each sample. The repeatability relative standard deviations (RSDr) for As ranged from 3.8 to 24%, for Cd from 2.6 to 6.9%, for Hg from 4.8 to 8.3%, and for Pb from 2.9 to 27%. The reproducibility relative standard deviations (RSDR) for As ranged from 9.0 to 28%, for Cd from 2.8 to 18%, for Hg from 9.9 to 24%, and for Pb from 8.0 to 50%. The HorRat values were less than 1.5 for all test samples, except for the determination of Pb in wheat flour at a level close to the limit of quantitation (0.01 mg/kg dm). The study showed that the ICP/MS method is satisfactory as a standard method for elemental determinations in foodstuffs.
Development and Evaluation of Thin-Layer Chromatography-Digital Image-Based Analysis for the Quantitation of the Botanical Pesticide Azadirachtin in Agricultural Matrixes and Commercial Formulations: Comparison with ELISA
Authors: Tanuja Penmatsa , Venugopal Namburi , Sashidhar Rao Beedu
Published: February 2020

A simple thin-layer chromatography-digital image-based analytical method has been developed for the quantitation of the botanical pesticide, azadirachtin. The method was validated by analyzing azadirachtin in the spiked food matrixes and processed commercial pesticide formulations, using acidified vanillin reagent as a postchromatographic derivatizing agent. The separated azadirachtin was clearly identified as a green spot. The Rf value was found to be 0.55, which was similar to that of a reference standard. A standard calibration plot was established using a reference standard, based on the linear regression analysis [r2 = 0.996; y = 371.43 + (634.82)x]. The sensitivity of the method was found to be 0.875 g azadirachtin. Spiking studies conducted at the 1 ppm (g/g) level in various agricultural matrixes, such as brinjal, tomato, coffee, and cotton seeds, revealed the recoveries of azadirachtin in the range of 6792%. Azadirachtin content of commercial neem formulations analyzed by the method was in the range of 1901825 ppm (g/mL). Further, the present method was compared with an immunoanalytical method enzyme-linked immonosorbent assay developed earlier in our laboratory. Statistical comparison of the 2 methods, using Fischer's F-test, indicated no significant difference in variance, suggesting that both methods are comparable.
Determination of Domoic Acid Toxins in Shellfish by Biosense ASP ELISAA Direct Competitive Enzyme-Linked Immunosorbent Assay: Collaborative Study
Authors: Kleivdal Hans , Kristiansen Sven-Inge , Nilsen Mona V , Goksyr Anders , Briggs Lyn , Holland Patrick , McNabb Paul ,   Collaborators:, Aasheim A , Aune T , Bates S , Bavington C , Caron D , Doucette G , Gago-Martinez A , Gallacer S , Grieve M , Haley S , Hess P , Hughes P , Léger C , Macaillou-Le Baut C , Myrland C , Neil T , Nguyen L , Ross K , Samdal I , Schaffner R , Smith E , Sosa S , Towers N , Tubaro A , Vaquero E , Wells M , Werner M , White P
Published: February 2020

A collaborative study was conducted on the Biosense amnesic shellfish poisoning (ASP) enzyme-linked immunosorbent assay (ELISA) for the determination of domoic acid (DA) toxins in shellfish in order to obtain interlaboratory validation data for the method. In addition, a method comparison study was performed to evaluate the ASP ELISA as an alternative to the current liquid chromatography (LC) reference method for DA determination. The study material comprised 16 shellfish samples, including blue mussels, Pacific oysters, and king scallops, spiked with contaminated mussel homogenates to contain 0.120 mg DA/kg shellfish flesh. The shellfish samples were extracted with 50% aqueous methanol, and the supernatants were directly analyzed. Sixteen participating laboratories in 10 countries reported data from the ASP ELISA, and 4 of these laboratories also reported data from instrumental LC analysis. The participating laboratories achieved interlaboratory precision estimates for the 8 Youden paired shellfish samples in the range of 1020% for RSDr (mean 14.8 4%), and 1329% for RSDR (mean 22.7 6%). The precision estimates for the ELISA data did not show a strong dependence on the DA concentration in the study samples, and the overall precision achieved was within the acceptable range of the Horwitz guideline with HorRat values ranging from 1.1 to 2.4 (mean HorRat 1.7 0.5). The analysis of shellfish samples spiked with certified reference material (CRM)-ASP-MUS-b gave recoveries in the range of 88122%, with an average recovery of 104 10%. The estimate on method accuracy was supported by a correlation slope of 1.015 (R2 = 0.992) for the determined versus the expected DA values. Furthermore, the correlation of the ASP ELISA results with those for the instrumental LC analyses of the same sample extracts gave a correlation slope of 1.29 (R2 = 0.984). This indicates some overestimation of DA levels in shellfish by the ELISA, but it is also a result of apparent low recoveries for the LC methods. This interlaboratory study demonstrates that the ASP ELISA is suitable for the routine determination and monitoring of DA toxins in shellfish, and that it offers a rapid and cost-effective methodology with high sample throughput.
Use of Multitoxin Immunoaffinity Columns for Determination of Aflatoxins and Ochratoxin A in Ginseng and Ginger
Authors: Trucksess Mary W , Weaver Carol M , Oles Carolyn J , Rump Lydia V , White Kevin D , Betz Joseph M , Rader Jeanne I
Published: February 2020

Conditions were optimized for the simultaneous, alkaline, aqueous methanol extraction of aflatoxins (AFL), i.e., B1 (AFB1), B2 (AFB2), G1 (AFG1), and G2 (AFG2), and ochratoxin A (OTA) with subsequent purification, isolation, and determination of the toxins in ginseng and ginger. Powdered roots were extracted with methanol0.5% NaHCO3 solution (7 + 3). After shaking and centrifugation, the supernatant was diluted with 100 mM phosphate buffer containing 1% Tween 20 and filtered through glass microfiber filter paper. The filtrate was then passed through an immunoaffinity column, and the toxins were eluted with methanol. The AFL were separated and determined by reversed-phase liquid chromatography (RPLC) with fluorescence detection after postcolumn UV photochemical derivatization. OTA was separated and determined by RPLC with fluorescence detection. Recoveries of AFL added at 216 ng/g and OTA added at 18 ng/g to ginseng were 7280 and 8695%, respectively. Recoveries of AFL and OTA added to ginger were similar to those for ginseng. A total of 39 commercially available ginger products from 6 manufacturers were analyzed. Twenty-six samples were found to be contaminated with AFL at 131 ng/g and 29 samples, with OTA at 110 ng/g. Ten samples contained no AFL or OTA. Ten ginseng finished products were also analyzed; 3 contained AFL at 0.1 ng/g and 4 contained OTA at levels ranging from 0.4 to 1.8 ng/g. LC/tandem mass spectrometry with multiple-reaction monitoring of 3 collisionally induced product ions from the protonated molecular ions of OTA, AFB1, and AFG1 was used to confirm the identities of the toxins in extracts of the finished products.
Identification of Lactic Acid Bacteria within the Consortium of a Kefir Grain by Sequencing 16S rDNA Variable Regions
Authors: Ninane Véronique , Mukandayambaje Radegonde , Berben Gilbert
Published: February 2020

The microflora of a kefir grain was identified using a polymerase chain reaction-based strategy combined with 16S rRNA gene sequencing. DNA was extracted from the kefir grain and amplified in its 16S rDNA V1 and V2 regions. To guarantee a good representation of the overall lactic acid bacteria populations, DNA amplification was performed separately with primers specific either to the dominant or to the less abundant bacterial groups. The amplified fragments were cloned in Escherichia coli and then sequenced. Sequences of the V1 region were gathered into 5 groups of similarity and identified by aligning with the sequences of a public library. The V1 region allowed the identification of Lactobacillus kefiranofaciens, L. kefir, L. parakefir, and Lactococcus lactis but was inappropriate for the identification of leuconostocs at species level. Among 16S rDNA variable regions, the V2 region showed the highest variability between Leuconostoc species. Nevertheless, even in the V2 region, differences were too tenuous for effective identification of L. mesenteroides. The methodology described here allowed detection of the dominant species within each targeted microbial group.
Interlaboratory Comparison for the Determination of Five Residual Organochlorine Pesticides in Ginseng Root Samples by Gas Chromatography
Authors: Kong Mei-Fung , Chan Serena , Wong Yiu-Chung , Wong Siu-Kay , Sin Della Wai-Mei
Published: February 2020

An interlaboratory comparison study for the determination of 5 residual organochlorine pesticides (hexachlorobenzene and 4 hexachlorocyclohexane isomers) in ginseng root was performed. This program [Asia Pacific Laboratory Accreditation Cooperation (APLAC) T049] was the first of its kind for an herbal matrix and involved the participation of 70 laboratories from 26 countries worldwide. Consensus mean values were computed statistically from the reported results, which were eventually used to assess the performance of individual laboratories in terms of the z-scores. The distribution of analytical data was found to be widespread, with standard deviation ranging from 43.9 to 55.9%, and the result patterns obtained were similar to those residue pesticide programs using other matrixes. Although the estimation of measurement uncertainty is a crucial requirement for all quantitative tests for laboratories that meet the requirements of International Organization for Standardization/International Electrotechnical Commisssion (ISO/IEC) 17025, some laboratories in this program had difficulties and showed unfamiliarity with respect to that quality criterion. It was recommended that laboratories review and rectify the situation promptly so that they would have a better understanding of measurement uncertainty or the test service provided.
Simultaneous Analysis of 260 Pesticide Residues in Agricultural Products by Gas Chromatography/Triple Quadrupole Mass Spectrometry
Authors: Okihashi Masahiro , Takatori Satoshi , Kitagawa Yoko , Tanaka Yukio
Published: February 2020

A method for simultaneous analysis of about 260 pesticides by gas chromatography coupled to tandem mass spectrometry (GC/MS/MS) with a triple quadrupole analyzer (QqQ) has been studied. The pesticides were extracted with acetonitrile and cleaned up by a bilayer cartridge. A single injection method was developed for the monitoring of all of the targeted pesticides. Two MS/MS transitions were selected for each analyte using the intensity ratio obtained from them as a confirmatory parameter. By using matrix-matched standards, 260 pesticides could be determined in most matrixes with recoveries of 70120% and a standard deviation of 20 at 2 different fortification levels of 0.02 and 0.1 g/g. The developed method was applied to the monitoring of 173 agricultural product samples from the local market. The sensitivities of this method were lower than with most of the selective GC detectors, such as flame photometric or single MS. The selectivity of QqQ gives a very clean chromatogram, making compound identification and confirmation easy. The quick and reliable monitoring was achieved by combination with rapid extraction and cleanup.