bluuebunny/crossref_metadata_2025_split huggingface dataset:
Importance of Enzyme Purity and Activity in the Measurement of Total Dietary Fiber and Dietary Fiber Components
Authors: McCleary Barry V 
Published: February 2020

Abstract
A study was made of the effect of the activity and purity of enzymes in the assay of total dietary fiber (AOAC Method 985.29) and specific dietary fiber components: resistant starch, fructan, and β-glucan. In the measurement of total dietary fiber content of resistant starch samples, the concentration of α-amylase is critical; however, variations in the level of amyloglucosidase have little effect. Contamination of amyloglucosidase preparations with cellulase can result in significant underestimation of dietary fiber values for samples containing β-glucan. Pure β-glucan and cellulase purified from Aspergillus niger amyloglucosidase preparations were used to determine acceptable critical levels of contamination. Sucrose, which interferes with the measurement of inulin and fructooligosaccharides in plant materials and food products, must be removed by hydrolysis of the sucrose to glucose and fructose with a specific enzyme (sucrase) followed by borohydride reduction of the free sugars. Unlike invertase, sucrase has no action on low degree of polymerization (DP) fructooligosaccharides, such as kestose or kestotetraose. Fructan is hydrolyzed to fructose and glucose by the combined action of highly purified exo- and endo-inulinases, and these sugars are measured by the p-hydroxybenzoic acid hydrazide reducing sugar method. Specific measurement of β-glucan in cereal flour and food extracts requires the use of highly purified endo-1,3:1,4 β-glucanase and A. niger β-glucosidase. β-Glucosidase from almonds does not completely hydrolyze mixed linkage β-glucooligosaccharides from barley or oat β-glucan. Contamination of these enzymes with starch, maltosaccharide, or sucrose-hydrolyzing enzymes results in production of free glucose from a source other than β-glucan, and thus an overestimation of β-glucan content. The glucose oxidase and peroxidase used in the glucose determination reagent must be essentially devoid of catalase and α- and β-glucosidase.
Variability of Deoxynivalenol Measurements in Barley
Authors: Freese Larry , Friedrich Roger , Kendall Donald , Tanner Steven 
Published: February 2020

Abstract
Deoxynivalenol (DON), a toxin produced by Fusarium fungi, can occur in many cereal grains. If wet climatic conditions coincide with the flowering period of plant development, circumstances are favorable for the fungi infection. Because the presence of DON in barley can have significant economic consequences to barley producers, commercially available test kits are used to measure DON in shipments throughout marketing channels. The quantity of barley sampled from a lot and used to measure DON can vary widely, depending on where the test is conducted. The Grain Inspection, Packers and Stockyards Administration of the U.S. Department of Agriculture specifies that a minimum of 100 g of grain must be processed to measure DON. Other laboratories may use more or less grain. A study undertaken to measure the variability among measurements of different sample sizes found no detectable differences in variability attributable to sample size. It was concluded that the variability among DON concentrations in samples from the lot was small relative to that introduced by the measurement process (combined sample preparation and analysis). A separate experiment investigated variation among samples taken from a lot, variation among subsamples taken from ground samples, and variation among multiple replicated measurements of an extract. On 10 lots, all 3 sources were significant contributors to variation. Stratification of DON within lots was hypothesized as a source of variation of DON measurements. Tests indicated that some stratification may exist.
Testing Shelled Corn for Aflatoxin, Part I: Estimation of Variance Components
Authors: Johansson Anders S , Whitaker Thomas B , Hagler Winston M , Giesbrecht Francis G , Young James H , Bowman Daryl T 
Published: February 2020

Abstract
The variability associated with testing lots of shelled corn for aflatoxin was investigated. Eighteen lots of shelled corn were tested for aflatoxin contamination. The total variance associated with testing shelled corn was estimated and partitioned into sampling, sample preparation, and analytical variances. All variances increased as aflatoxin concentration increased. With the use of regression analysis, mathematical expressions were developed to model the relationship between aflatoxin concentration and the total, sampling, sample preparation, and analytical variances. The expressions for these relationships were used to estimate the variance for any sample size, subsample size, and number of analyses for a specific aflatoxin concentration. Test results on a lot with 20 parts per billion aflatoxin using a 1.13 kg sample, a Romer mill, 50 g subsamples, and liquid chromatographic analysis showed that the total, sampling, sample preparation, and analytical variances were 274.9 (CV = 82.9%), 214.0 (CV = 73.1%), 56.3 (CV = 37.5%), and 4.6 (CV = 10.7%), respectively. The percentage of the total variance for sampling, sample preparation, and analytical was 77.8, 20.5, and 1.7, respectively.
Analysis of Ginkgo biloba for the Presence of Ginkgotoxin and Ginkgotoxin 5′-Glucoside
Authors: Scott Peter M , Lau Benjamin P-Y , Lawrence Guillaume A , Lewis David A 
Published: February 2020

Abstract
Hot water extracts of Ginkgo biloba seeds were analyzed for the presence of ginkgotoxin (4′-O-methylpyridoxine) by reversed-phase liquid chromatography (LC) using methanol–0.05M KH2PO4 (1 + 9, v/v) adjusted to pH 3 as mobile phase. Detection was by fluorescence (excitation 280 nm, emission 370 nm). A straight line calibration curve was obtained for the 10–100 ng injected. After addition of β-glucosidase (37°C/h), an earlier eluting peak disappeared and the ginkgotoxin peak increased. The identity of the ginkgotoxin was confirmed by LC/MS and LC/MS/MS. LC/MS/MS also confirmed the 5′-glucoside by comparison with the 3-glucoside. This is the first identification of a glucoside of ginkgotoxin in Ginkgo biloba. An unknown compound of MW 267 also observed in the Ginkgo biloba seed extract was shown not to be 3,5′-diacetylginkgotoxin by its different LC retention time. Extraction of ground Ginkgo biloba seeds with boiling water in a Soxhlet for 2 × 2 h yielded a total of 179 μg/g of free ginkgotoxin. The concentration in powder from Ginkgo biloba capsules was several times lower than this (17–64 μg/g) in 3 samples but higher in another (457 μg/g). Canned ginkgo seeds (white nuts) contained no detectable free ginkgotoxin but the glucoside was present. Different extraction times were studied: 0.5 h gave only 52 μg/g free ginkgotoxin in the ginkgo seeds. However, boiling an extract for 4 h showed about 15% loss of ginkgotoxin and its glucoside.
Liquid Chromatographic Method with Immunoaffinity Column Cleanup for Determination of Ochratoxin A in Barley: Collaborative Study
Authors: Entwisle A Catherine , Williams Alison C , Mann Peter J , Slack Philip T , Gilbert John 
Published: February 2020

Abstract
A collaborative study was conducted to evaluate a liquid chromatographic (LC) method with immunoaffinity column cleanup for determination of ochratoxin A. The method was tested at 3 concentration levels of ochratoxin A in barley, which represent possible future European regulatory limits. The test portion was extracted with acetonitrile–water by blending at high speed. The extract was filtered, diluted with phosphate-buffered saline (PBS), and applied to an ochratoxin A immunoaffinity column. The column was washed with water and the ochratoxin A eluted with methanol. The solvent was then evaporated and the residue redissolved in injection solvent. After injection of this solution onto reversed-phase LC column, ochratoxin A was measured by fluorescence detection. Eight samples of low level naturally contaminated barley and 2 samples of blank barley (ochratoxin A not found at the limit of detection of 0.2 μg/kg at the signal-to-noise ratio of 3 to 1) were sent, along with ampules of ochratoxin A, calibrant, and spiking solutions, to 15 laboratories in 13 different European countries. Test portions were spiked with ochratoxin A at levels of 4 ng/g, and recoveries ranged from 65 to 113%. Based on results for spiked samples (blind duplicates) and naturally contaminated samples (blind duplicates at 3 levels), the relative standard deviation for repeatability (RSDr) ranged from 4 to 24%, and the relative standard deviation for reproducibility (RSDR) ranged from 12 to 33%. The method showed acceptable within- and between-laboratory precision, as evidenced by HORRAT values, at the low level of determination for ochratoxin A in barley.
Deuterium Nuclear Magnetic Resonance Spectroscopy and Stable Carbon Isotope Ratio Analysis/Mass Spectrometry of Certain Monofloral Honeys
Authors: Giraudon Sylvie , Danzart Marc , Merle Marc H 
Published: February 2020

Abstract
Quantitative deuterium nuclear magnetic resonance spectroscopy (NMR) has been used in conjunction with stable carbon isotope ratio analysis/mass spectrometry to refine the detection of sugars that have been added to monofloral honeys. The 13C content of sugars indicates the type of photosynthetic metabolism of the plant that synthesized them; the deuterium content is more characteristic of secondary metabolism and of environmental factors. Consequently, determination of the 13C content of honeys and of proteins extracted from the honeys can be used to detect the addition of C4 plant sugars (cane or corn), but it does not reveal the addition of C3 plant sugars such as beet sugar. Deuterium NMR gives useful information for some monofloral honeys. NMR measurement is performed on ethanol obtained from fermentation of the honey and extracted by distillation. The isotopic composition of the ethanol indicates the nature of the sugars from which it was derived. Various types of monofloral honeys were studied, and the results obtained with commercially available honeys demonstrate the usefulness of isotopic analysis and the need to compile a database of authentic honeys to validate or affirm certain results.
Evaluating Presence/Absence of Target Microbes in Microbiological Tests
Authors: Blodgett Robert J , Hitchins Anthony D 
Published: February 2020

Abstract
A typical qualitative microbiological method performance (collaborative) study gathers a data set of responses about a test for the presence or absence of a target microbe. We developed 2 models that estimate false-positive and false-negative rates. One model assumes a constant probability that the tests will indicate the target microbe is present for any positive concentration in the test portion. The other model assumes that this probability follows a logistic curve. Test results from several method performance studies illustrate these estimates.
Determination of α-Solanine and α-Chaconine in Potatoes by High-Performance Thin-Layer Chromatography/Densitometry
Authors: Bodart Patricia , Kabengera Charles , Noirfalise Alfred , Hubert Philippe , Angenot Luc 
Published: February 2020

Abstract
A high-performance thin-layer chromatographic (HPTLC) method was used to determine the glycoalkaloids α-solanine and α-chaconine in potatoes. α-Solanine and α-chaconine are extracted from dehydrated potatoes with boiling methanol–acetic acid (95 + 5, v/v). The analytes are separated on a Silica Gel 60 F254 HPTLC plate by a saturated mixture of dichloromethane–methanol–water–concentrated ammonium hydroxide (70 + 30 + 4 + 0.4, v/v), which is used for vertical development of the plate up to a distance of 85 mm. For visualization, the plate is dipped 3 times into a modified Carr-Price reagent, 20% (w/v) antimony(III) chloride in acetic acid–dichloromethane (1 + 3, v/v), and subsequently heated on a hot plate at 105°C for 5 min. The glycoalkaloids all appear as red chromatographic zones on a colorless background. Densitometric quantification is performed at 507 nm by reflectance scanning. After determination of the appropriate response function, the proposed method was validated. Good results with respect to linearity, accuracy, and precision were obtained in the concentration range studied.
Simultaneous Determination of Bergenin and Gallic Acid in Bergenia ligulata Wall by High-Performance Thin-Layer Chromatography
Authors: Chauhan Sateesh K , Singh Brijpal , Agrawal Sudhakar 
Published: February 2020

Abstract
A simple and reproducible high-performance thin-layer chromatographic method was developed for the simultaneous determination of bergenin and gallic acid in Bergenia ligulata. Water and methanol were used as the extracting solvents. The concentrations of bergenin and gallic acid in both of these solvents were found to be almost the same. The method involves separation of the components by thin-layer chromatography on a precoated Silica Gel 60 F254 plate with a solvent system of ethyl acetate–formic acid–acetic acid–water (100 + 11 + 11 + 27). The sensitivity of the method for bergenin was 0.30 μg, whereas for gallic acid it was 0.25 μg. The proposed method is precise and sensitive and can be used for the detection, monitoring, and simultaneous quantification of bergenin and gallic acid in B. ligulata.
Electroanalytical Determination of Cadmium and Lead in Deciduous Teeth after Microwave Oven Digestion
Authors: Bayo Javier , Moreno-Grau Stella , Martínez M José , Moreno José , Angosto José M , Moreno-Clavel Joaquín , Pérez José J Guillén , Marcos Luis García 
Published: February 2020

Abstract
A method using differential pulse anodic stripping voltammetry after microwave oven digestion was developed for the simultaneous determination of Cd(II) and Pb(II) in the deciduous teeth of children. Each tooth was weighed; deposited in a 120 mL capped Teflon vessel with 5 mL 65% nitric acid, Suprapur analytical grade; and digested in a 2-step microwave oven for 15 min. The detection limits for Cd(II) and Pb(II) in the final solution were 0.078 and 0.323 μg/L, and the quantitation limits 0.394 and 1.613 μg/L, respectively, with a linearity range of 2 μg/L for Cd(II) and 23.3 μg/L for Pb(II). The sensitivity was 2.51 nA/μg-L and 1.37 nA/μg-L, for Cd(II) and Pb(II). The main advantages of this technique are a complete and satisfactory dissolution of the tooth material with the proposed microwave oven digestion procedure, without sample pretreatments, such as drying, ashing, or powdering. The voltammetric procedure proved to be well designed because of significant goodness of fit to a linear model, and the accuracy of the method was established as compared with standard reference material. The methodology has enabled us to study Cd(II) and Pb(II) in 371 deciduous teeth from school children in Cartagena, Spain.
Polyclonal-Based ELISA for the Identification of Cyclohexanedione Analogs that Inhibit Maize Acetyl Coenzyme-A Carboxylase
Authors: Webb Steven R , Hall J Christopher 
Published: February 2020

Abstract
Cyclohexanedione herbicides inhibit monocotyledonous acetyl coenzyme-A carboxylase (ACCase; E.C. 6.4.1.2.), which catalyzes the first committed step in fatty acid biosynthesis. Although the target site has been identified, little is known about the mechanisms involved in herbicide binding. An immunological study was undertaken to create a model to better characterize the herbicide–enzyme interaction. Cyclohexanedione-specific antiserum was raised in New Zealand white rabbits by immunizing them with a cyclohexanedione analog–bovine serum albumin conjugate. Two indirect enzyme-linked immunosorbent assays (ELISA) were developed using 2 different cyclohexanedione analogs conjugated to ovalbumin as coating conjugates. Nineteen cyclohexanedione analogs, 13 active ACCase inhibitors, and 6 inactive analogs were tested for their ability to compete with both coating conjugates for antiserum binding. All active ACCase inhibitors were observed to compete with both coating conjugates, whereas all inactive analogs failed to compete with at least one coating conjugate. On the basis of these results, the immunological model could be used to distinguish all active ACCase inhibitors from inactive analogs using the 2 ELISAs sequentially.
Analytical Study of Comprehensive and Targeted Multidimensional Gas Chromatography Incorporating Modulated Cryogenic Trapping
Authors: Truong Thy T , Marriott Philip J , Porter Nichola A 
Published: February 2020

Abstract
This paper reports the results of an analytical study comparing capillary gas chromatography (GC) operated in the normal mode with 2 new GC techniques, comprehensive GC (GC × GC) and targeted (or selective) multidimensional GC, which use a longitudinally modulated cryogenic system (LMCS), recently developed in our laboratory. A high-temperature application of derivatized sterols, of interest in fecal pollution monitoring, was chosen for this work. A directly connected coupled-column ensemble was used, comprising a nonpolar column and a moderately polar column. With LMCS, effluent from the first column is zone-compressed in a cryogenic trap and then pulsed to a short second column, producing narrower peaks with sharp, tall peak responses at the detector. The modulator is operated at a constant frequency, e.g., 0.25 s−1, to produce the GC × GC result, or is moved in a predefined manner so that whole peaks are selectively trapped and subsequently pulsed through to the second column in the targeted mode. Standard solutions containing a mixture of 7 sterols and 5-α-cholestane internal standard were used. Detection sensitivity is increased by a factor of ≥25 with the use of LMCS. The estimated limit of detection was about 0.1 μg/mL when normal GC with flame ionization detection (GC/FID) and a 1.0 μL splitless injection volume were used, compared with 0.02 and 0.004 μg/mL for the LMCS operated in GC × GC and selective modes, respectively. Calibration curves for GC/FID were linear over the 0.1–2.0 μg/mL range tested. Reproducibilities for the GC × GC and normal GC modes were comparable; generally, relative standard deviations (RSD) were on the order of 3–4%, based on raw peak responses. Improved reproducibility was found for selective LMCS operation, at an RSD of around 2%; with internal standardization, better results were achieved. The coupled-column arrangement allowed complete separation of sterol peaks from overlapping impurity peaks in a number of instances with LMCS modes, and its use should improve data quality over that of normal GC operation, in which the overlapping peaks interfere with measurement of peak response in the normal mode.
Determination of Phthalates in Crude Extracts of Sewage Sludges by High-Resolution Capillary Gas Chromatography with Mass Spectrometric Detection
Authors: Berset Jean-Daniel , Etter-Holzer Ruth 
Published: February 2020

Abstract
A simple solvent extraction by ethyl acetate without subsequent cleanup was used to determine 16 phthalic acid esters (PAEs), including bis(2-ethylhexyl) phthalate (DEHP), in sewage sludge samples from different catchment areas. The compounds were separated on a gas chromatographic capillary column with a nonpolar HT-8 stationary phase. For most of the PAEs, internal standard quantification with deuterated dibutyl phthalate (DBP) and deuterated DEHP was best achieved by using electron ionization mass spectrometry in the selected-ion monitoring mode. Because of its high concentrations in the sludges, DEHP was quantified in the full-scan acquisition mode. Molecular weight and ester-type information for the PAEs was obtained in the positive chemical ionization mode with methane as the reagent gas. Finally, selected sewage sludges containing different amounts of industrial wastewater were analyzed by the proposed method. DEHP was the most abundant compound found at 21–114 mg/kg·dm, followed by the lower-molecular weight PAEs diethyl phthalate, diisobutyl phthalate, and DBP and the higher-molecular weight compounds butylbenzyl phthalate, dicyclohexyl phthalate, di-n-octyl phthalate, and dinonyl phthalate, which were present mostly at &lt;1 mg/kg·dm.
Solid-Phase Microextraction for the Enantiomeric Analysis of Flavors in Beverages
Authors: Ebeler Susan E , Sun Gay M , Datta Meera , Stremple Phil , Vickers Allen K 
Published: February 2020

Abstract
Solid-phase microextraction combined with gas chromatographic/mass spectrometric analysis and separation on a chiral cyclodextrin stationary phase was a rapid, reliable technique for profiling chiral aroma compounds in flavored alcoholic beverages. Several enantiomeric terpenes, esters, alcohols, norisoprenoids, and lactones were identified in berry-, peach-, strawberry-, and citrus-flavored wine and malt beverages (wine coolers). Using this technique, we were able to confirm the addition of synthetic flavoring to several beverages, consistent with label designations.
Complexation Equilibria and Spectrophotometric Determination of Iron(III) with Resorcylic Acid
Authors: Hashem Elham Y 
Published: February 2020

Abstract
The complexation equilibria of Fe(III) with resorcylic acid (2,4-dihydroxybenzoic acid, DHB) were studied spectrophotometrically in ethanol–water (4 + 6, v/v) at an ionic strength of 0.1M NaClO4. The complexation reactions were demonstrated and characterized. A simple, rapid, and sensitive method based on the formation of the Fe(III)–DHB complex at pH 2.5 (λmax = 520 nm, ε = 0.8 × 104 L/mol·cm) was developed for the spectrophotometric determination of Fe(III). The effect of diverse ions on the sensitivity of the proposed method was studied. The Fe–DHB complex was isolated and characterized by both elemental analysis and infrared spectroscopy. The thermal behavior of the complex in dynamic nitrogen gas was studied by thermogravimetric and differential thermogravimetric analysis. Thermal events encountered throughout the course of decomposition were monitored. A computer program was used for regression analysis and for determination of kinetic and thermodynamic parameters from experimental nonisothermal thermogravimetric data. The proposed method was tested by determinations of iron in various synthetic samples and Portland cement materials.
Variations of Moisture Measurements in Cheese
Authors: Emmons Douglas B , Bradley Robert L , Sauvé J Paul , Campbell Carol , Lacroix Christophe , Jimenez-Marquez Sergio A 
Published: February 2020

Abstract
Data were accumulated during interlaboratory trials for cheese moisture determination from laboratories using officially recognized methods: AOAC; International Dairy Federation, and Standard Methods for the Examination of Dairy Products (SM). In one trial, ranges of means of 5 cheeses were 0.67, 0.56, and 0.19% for 5, 9, and 8 laboratories, respectively. The lower ranges for the SM method were typical of 3 other interlaboratory trials, with ranges of 0.27, 0.34, and 0.34% for 6, 7, and 5 laboratories, respectively. Within one laboratory, there were no significant differences among the 3 methods, but they all gave about 0.2% lower results than 2 other methods, one using freeze-drying, followed by drying in a vacuum, the other using cheese that was spread on sand and dried in a vacuum oven for 24 h. This finding indicated that none of the officially recognized methods removed all the moisture. Data showed that many laboratories tended to give either higher or lower results than the mean of all of them in a series of 7 interlaboratory trials. Constant results, free of biases or systematic errors, are important in application of formulas for prediction of yield of cheese for purposes of yield control, but are difficult to obtain. It is proposed that results by a laboratory in interlaboratory trials be compared with those obtained by one or more reference laboratories using a method that removes all the moisture from cheese. The difference would be applied as a constant in the predictive yield formula. That difference would likely be best as a running mean of differences in an ongoing series of trials. The reference laboratories would use frozen samples for quality control to ensure uniformity of results among trials. Mean moistures of 36.10 and 36.11% were obtained on subsamples before and after freezing for 7 months.