bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Sodium in Biological Materials by Instrumental Neutron Activation Analysis
Authors: Cunningham William C , Capar Stephen G , Anderson David L
Published: February 2020

A formalized method for determining sodium in biological materials by instrumental neutron activation analysis is presented. The method includes common procedures from the numerous options available to this historically nonformalized analytical technique. The number of procedural options is restricted to minimize the method’s complexity, yet the method is still applicable to a variety of neutron activation facilities. High accuracy and precision are achieved by placing bounds on allowed uncertainty at critical stages of the analysis. Analytical results from the U.S. Food and Drug Administration laboratory and 4 other laboratories demonstrate the method’s performance.
Bioavailability and Speciation of Mineral Micronutrients: The Enzymolysis Approach
Authors: Hocquellet Pierre , L'Hotellier Marie-Dominique
Published: February 2020

Speciation analyses are essential to investigate the effects of dietary components on bioavailability of mineral micronutrients. Enzymolysis was used. An in vitro model simulating enzymatic activity in the gastrointestinal tract of monogastric species was developed and used to assess availability of Fe, Cu, Mn, and Zn in some foodstuffs. The solubility of each element in samples was measured by atomic absorption spectrometry after enzymatic treatment. Data are in good agreement with information obtained from earlier, more expensive nutritional surveys or in vivo experiments and, therefore, allow prediction of the tendency of a particular food to induce mineral deficiency. In addition, ligands responsible for inhibiting intestinal absorption were identified by determining the amount of metal released after treatment of the insoluble residue with an appropriate enzyme such as cellulase and phytase, used respectively to study fiber and phytate interactions. Enzymolysis may be useful for optimizing mineral supplementations though its nutritional significance is somewhat limited by the fact that it does not take into account the dynamic changes in the gastrointestinal tract. Enzymolysis is a prerequisite for further speciation studies of complex systems and in some instances is the only way for specifying physicochemical forms of elements.
Rapid and Alternative Screening Methods for Microbiological Analysis
Authors: Van Der Zee Henk , Huis In T Veld Jos H J
Published: February 2020

Automated analytical instruments for enumerating indicator organisms and diagnostic test kits for pathogens can be used in food microbiology to screen samples and to replace conventional cultural and confirmation steps. Such methods are now available for rapid detection or estimation of groups of (indicator) organisms, pathogenic microorganisms, bacterial toxins and mycotoxins, and molds. These alternative methods can be classified by the principles on which they are based: modified conventional methods, instrumental measurement of bacterial metabolism, bioluminescence, immunological techniques, DNA techniques, and combinations of these techniques. To meet user expectations, test kits must be accurate, sensitive, specific, rapid (24 h or less), easy to use, and laborsaving. They must also offer the possibility of computerization, a low detection limit, and low investment and running costs. The paper compares the ability of alternative methods to meet these criteria. Variations were found, depending on the techniques used and the target organism of the analysis. Economic reasons can determine whether alternative methods can be used routinely. Adoption of these screening systems also can be hampered by lack of internationally coordinated and accepted validation protocols.
New Universal Quartz Burner for Decomposition of Samples by the Wickbold Combustion Technique in Determination of Arsenic, Antimony, Selenium, Mercury, and Lead
Authors: Erber Dietmar , Cammann Karl , Roth JüRgen
Published: February 2020

A new universal quartz burner for the Wickbold decomposition method is investigated with respect to its fast and efficient decomposition of solid samples for determining volatile trace elements like arsenic, antimony, selenium, mercury, and lead. Decomposition is based on burning samples in an oxyhydrogen flame. The samples are transported into the flame in gaseous form by pyrolyzing the material in an oven heated to 1100C. During this decomposition step, a nitrogen stream loaded with carbon tetrachloride mobilizes the volatile elements, causing separation from the sample matrix. An effective precombustion in oxygen and a large turbulent flame improve decomposition conditions. Different certified inorganic and organic reference materials are pyrolyzed and combusted, and the combustion products are absorbed in water. Metals found in the absorption solutions are analyzed by flow injection/hydride generation/atomic absorption spectrometry. Data were analyzed by several statistical tests recommended for quality control purposes. The combination of a decomposition and detection method resulted in very low detection limits: 1.4 μg arsenic/kg, 0.8 pig antimony/kg, 1.8 μg mercury/kg, 1.4 μg lead/kg, and 1.6 μg selenium/ g can be detected without an extra enrichment step.
Identification and Quantitation of the Six Active Compounds in a Pyrethrin Standard
Authors: Moorman Richard , Nguyen Khanh T
Published: February 2020

Six biologically active insecticidal compounds in pyrethrum extract—pyrethrin I (Py I), jasmolin I (J I), cinerin I (C I), pyrethrin II (Py II), jasmolin II (J II), and cinerin II (C II)—have been identified and quantitated using a procedure combining the modified version of the AOAC mercury reduction Method 936.05 and capillary gas chromatography with flame ionization detection (GC-FID), GC with mass selective detection, and GC with infrared detection. This method involves hydrolysis of pyrethrum extract and subsequent measurement of monocarboxylic and dicarboxylic acids. Mass and infrared spectra are used to identify the 6 active compounds, and GC-FID is used to determine their purities. The use of this characterized standard is limited to a proposed capillary GC AOAC method that quantitates AAoctyl bicycloheptene dicarboximide (MGK264), pyrethrin, and butylcarbityl 6- propylpiperonyl ether (BPE) in technical materials, concentrates, and certain finished products.
Planar Chromatography for Quantitative Determination of Ampicillin Residues in Milk and Muscle
Authors: Abjean Jean-Pierre , Lahogue Véronique
Published: February 2020

A method involving protein precipitation with trichloroacetic acid and ampicillin hydrolysis with sodium hydroxide was developed for determination of ampicillin residue in milk and muscle. The hydrolysis product reacts in an acidic medium, in the presence of mercuric chloride, to form a fluorescent compound, which is extracted from the matrix with dichloromethane and concentrated on a silica Sep-Pak cartridge in a single step. After elution of the silica cartridge and evaporation of the solvent, the residue is recovered in 100 μL ethyl acetate, and 20 μL is deposited on a chromatoplate and chromatographed with ethyl acetate. The method allows determination of ampicillin residues in milk and muscle fortified at 4 μg/L and 50 μg/kg, respectively.
Determination of Nicarbazin in Eggs by Liquid Chromatography–Atmospheric Pressure Chemical Ionization Mass Spectrometry
Authors: Blanchflower W John , Hughes Peter J , Kennedy D Glenn
Published: February 2020

A method was developed to determine in eggs 2 components [4,6-dimethyl-2-hydroxypyrimidine and 1,3-bis(4-nitrophenyl)urea] of the anticoccidial drug nicarbazin, used to treat poultry. Samples were extracted with acetonitrile, and the extracts were washed with hexane and evaporated to dryness before analysis by liquid chromatography/mass spectrometry with atmospheric pressure chemical ionization. By switching from positive to negative ion monitoring and using gradient elution, both components were measured within one run. The limit of quantitation of the assay was 10 ng/g for each component. The results of a preliminary feeding trial in which chickens were fed contamination levels of the drug are also reported.
Induction and Characterization of Multianalyte Antibodies Against Penicillins in Egg Yolk
Authors: de Leuw Peter , Kapa Georg , Petz Michael
Published: February 2020

Antibodies against penicillins were induced in eggs of laying hens after immunization with 6-aminopeniciIlanic acid (6-APA) coupled to keyhole limpet hemocyanin (KLH). Development of the antibody titer was monitored by an indirect enzyme-linked immunosorbent assay (ELISA), with 6-APA coupled to ovalbumin as antigen for coating microtiter plates. Different characteristics (time course, affinity) of the immune reaction were observed by testing eggs of individual hens. Titer values varied between 150 and 2000. Antibodies were isolated by polyethylene glycol precipitation and affinity chromatography, using a hapten sorbent with 6-APA as ligand. Glycine buffer, pH 3.0, was used to elute the immunoglobulins. Antibody specificity was determined in a competitive ELISA with 7 penicillins and the cephalosporin cephalexin as competitors. Cross reactivities for the penicillins were between 100 and 290% (6-APA = 100%). Cephalexin cross reacted only marginally (3%).
Survey of Organochlorine Pesticide Residues in Milk in Hong Kong (1993–1995)
Authors: Wong Siu-Kay , Lee Wai-On
Published: February 2020

A survey was conducted from 1993 through 1995 to monitor organochlorine pesticides and their metabolite residues in milk available in local Hong Kong markets. Of 252 samples analyzed, including pasteurized milk, fresh milk, and raw milk, 42 contained organochloride pesticide residues at levels exceeding the Extraneous Maximum Residue Limits of the Codex Committee on Pesticide Residues. DDE and HCH isomer levels were substantially higher than those found in a 1984–1987 survey, probably because the source of cow’s milk has shifted from local dairy industries to mainland China over the past decade. Although organochlorine pesticides such as DDT and HCH have been banned in China since 1983, residues of such compounds may still persist in the environment and cause contamination through the food chain.
Determination of vitamin a in milk and flour consumed by one- to four-year-old children in côte d'ivoire
Authors: Ake Michele , Mandrou Bernadette , Malan Anglade
Published: February 2020

As part of a United Nations Children's Found (UN¬ICEF) study, an analytical method is proposed for routine analysis of vitamin A in milk and flour consumed by 1- to 4-year-old children in Côte d'Ivoire. The method involves liquid-liquid extrac¬tion of sample followed by reversed-phase liquid chromatography (LC). The method has been vali¬dated and used to analyze various samples col¬lected at different locations and stored under unfa¬vorable conditions. Average vitamin A content was 575 μg/100 g for milk powder and 1350 μg/100 g for millet flour. Lower contents were found in corn flour (40-240 μg/100 g), and no vitamin A could be detected in rice flour
Preparation of Environmental Samples for Determination of Sulfonylurea Herbicides by Solid-Phase Extraction Using a Polymeric Sorbent
Authors: Young Michael S
Published: February 2020

An analytical procedure was developed for rapid determination of sulfonylurea herbicides in water or soil. Samples were prepared by solid-phase extraction using polymeric sorbents in cartridges and analyzed by liquid chromatography with photodiode array detection. Recoveries were consistent for all sample matrixes tested and were generally >85%, except for tribenuron methyl (75%). Detection limits were <100 ng/L for water samples
Hyphenated Techniques in Thin-Layer Chromatography
Authors: Cserháti Tibor , Forgács Esther
Published: February 2020

abstract

This special report deals with the critical evaluation of the present state of hyphenated techniques in thin-layer chromatography, the enumeration of possible advantages and disadvantages of the newest developments, and prerequisites for the successful application of the newest results.
Liquid Chromatographic Method for Determining Thiodicarb in Technical Products and Formulations: CIPAC Collaborative Study
Authors: Hanks Alan R ,   Collaborators:, Abedi J , De Aguila E , Bodzian F , Chatpong  , Chechik E , Chmil V , Duverney-Prêt P , Förster R , Gau W , Hussain  , Itier M , lurascu T , Manso L , Pocaba V , Ruffin  , Ryckel B De , Santos  , Schreuder R H , Sriplakich C , Sweeney P J , Tam K C , Tengler H , Thuet E , Weber  , Werner T
Published: February 2020

abstract

A liquid chromatographic method for determining thiodicarb in technical products and formulations was evaluated by 25 participants from 19 laboratories. Data from 19 laboratories were used in statistical analysis to characterize method performance.Two technical materials, a suspension concentrate, a wettable powder, and a water dispersable granule were analyzed. Thiodicarb was determined by reversed-phase liquid chromatography using a mobile phase of methanol and water. Chromatography was performed on a C8 column with detection at 254 nm. Quantitation was achieved by using an internal standard and peak area ratios.
Quantitation of Imidacloprid in Liquid and Solid Formulations by Reversed-Phase Liquid Chromatography:Collaborative Study
Authors: Macke Michelle M ,   Collaborators:, Ambrose Richard , Benke Lajos , Denning Ralph , Ryckel B de , Focht Charles , Laslo Bura , Manuweera Lalini , Ritland C L , Smilo A Richard , Stroh Steven , Tam K C , Tengler H , Xing Gu Yi
Published: February 2020

abstract

A liquid chromatographic (LC) method was developed for quantitation of the synthetic insecticide imidacloprid in liquid and solid formulations. Samples are dissolved or extracted in solvent and analyzed by reversed-phase LC with propiophenone as internal standard. Fourteen laboratories in 7 countries participated in the collaborative study of the method. Each collaborator was provided with reference standard, internal standard, and matched-pair samples of imidacloprid technical, flowable, wettable powder, fertilizer, and granular formulations. Collaborators were instructed to use peak area measurements for quantitation. The reversed-phase LC method for determination of imidacloprid in liquid and solid formulations has been adopted first action by AOAC INTERNATIONAL.
A Rapid and Selective Method for Determining Potential Nitrosating Agents in Cosmetic Products by Chemiluminescence Detection of Nitric Oxide
Authors: Chou Hardy J , Yates Ronald L
Published: February 2020

abstract

A method was developed for rapid and selective determination of potential nitrosating agents at the part-per-billion level in cosmetic products. These compounds are chemically reduced to nitric oxide, which is determined by its chemiluminescent reaction with ozone. Suspended materials and colors in cosmetic products do not interfere. Hence their removal before analysis is not required. A detection limit of 33 ppb, calculated as nitrite, was obtained. No false-positive interferences were observed from antifoaming agents, several AZ-nitroso compounds, and nitrate up to 20 ppm. Among cosmetic products surveyed, potential nitrosating agents were found at levels ranging from 113 to 5021 ppb. No consistent relationship was found between levels of potential nitrosating agents and N-nitrosamines in the same products. However, the highest levels of nitrosating agents were most often associated with the highest levels of N-nitrosamines known to be present in the products.
Determination of Reserpine and Rescinnamine in Rauwolfia serpentina Powders and Tablets: Collaborative Study
Authors: Ugo R Cieri ,   Collaborators:, Alexander Leland , Colon Miguel , Frost Danielle , Jhangiani Rita K , Takiar Neeru , Tam Nilsa , Walters Milda , Yuen Stella
Published: February 2020

abstract

A liquid chromatographic (LC) method for determining reserpine and rescinnamine in Rauwolfia serpentina powders and tablets, which uses fluorescence detection, was subjected to a collaborative study. The procedure for extraction and purification is a simplified version of that used in the current official method for analysis of these products. LC separations are performed on a normal- phase column. The mobile phase is methanol to which a small volume of an aqueous solution of 1-pentanesulfonic acid sodium salt can be added to achieve desired elution characteristics. Reserpine and rescinnamine elute at approximately the same time but can be individually quantitated by appropriate settings of the fluorescence detector. Reserpine is determined at an excitation wavelength of 280 nm and an emission wavelength of 360 nm, because rescinnamine is completely nonfluorescent at these wavelengths. Rescinnamine is determined at an excitation wavelength of 330 nm and an emission wavelength of 435 nm, because reserpine is completely nonfluorescent at these wavelengths. The following materials were used for the study: one sample of United States Pharmacopeia (USP) standard R. serpentina powder, one tablet type labeled as containing 100 mg R. serpentina and 2 tablet types labeled as containing 50 mg R. serpentina. For each of the 4 materials, 2 pairs of blind duplicates were prepared. Three materials were analyzed in duplicate by 8 laboratories. One of the 2 tablets labeled to contain 50 mg ft serpentina was analyzed only by 7 of 8 participating laboratories. Average combined content of reserpine and rescinnamine was 0.144% for the USP raw material and 0.132, 0.135, and0.137% for the 3 commercial tablets. Reproducibility relative standard deviation values were 5.72, 5.93, 8.61, and 3.48% and repeatability relative standard deviation values were 2.57, 4.87, 3.19, and 1.99% for the 4 samples. The Associate Referee conducted a study to determine recoveries of reserpine plus rescinnamine by this method from mixtures simulating sample extracts. Average recovery of 15 determinations was 100.1%, with a relative standard deviation of 1.3%. The LC method for determination of reserpine and rescinnamine in R. serpentina powders and tablets has been adopted first action by AOAC INTERNATIONAL.
Stability-Indicating Spectrophotometric and Densitometric Methods for Determination of Some Cephalosporins
Authors: Kelani Khadiga , Bebawy Lories I , Abdel-Fattah Laila
Published: February 2020

abstract

Two methods were developed for determination of intact ceftazidime (I), cefuroxime sodium (II), and cefotaxime sodium (III) in the presence of their degradation products. In the first method, first derivative spectrophotometry (D1) is used. The (D1) absorbance is measured at 268.6, 306, and 228.6 nm for I, II, and III, respectively. The first proposed method determines I, II, and III in concentration ranges of 5-50, 5-35, and 5-40 μg/mL, respectively, with corresponding mean accuracies of 99.7 ± 0.8, 100.1 ± 0.7, and 99.8 ± 0.8%. The method determines the intact drug in the presence of up to 90% degradation products for I, and II and up to 80% for III. The second method depends on the quantitative densitometric evaluation of thin-layer chromatograms of I, II, and III. It determines I, II, and III in concentration ranges of 4-16 μg for I and 2-12 μg for II and III, with mean accuracy's of 99.5 ± 0.8, 99.2 ± 0.7, and 99.7 ± 0.8% for I, II, and III, respectively. The second method retains its accuracy in the presence of up to 90% degradation products for the 3 drugs. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by the official method.
Zero Control Reference Materials for Infant Formula Methods Development
Authors: Chase G William , Reid Anne P , Eitenmiller Ronald R , Long Austin R
Published: February 2020

abstract

A zero control reference material (ZRM) for milk and soy-based infant formula was manufactured and characterized. The ZRM was free of retinyl palmitate and all-rac-α-tocopheryl acetate. The composition was similar to commercially available infant formula. The ZRM provides a valuable tool to ascertain method performance.
Performance of Fertilizer Methods as Measured by the Magruder Check Sample Program
Authors: Latimer George W
Published: February 2020

abstract

Thirteen years of data generated by participants in the Magruder fertilizer check sample program were used to compare the performance of methods for analyzing fertilizers.
Determination of N-Octyl Bicycloheptene Dicarboximide, Pyrethrins, and Butylcarbityl 6-Propylpiperonyl Ether in Technical Materials, Concentrates, and Finished Products by Capillary Gas Chromatography: Collaborative Study
Authors: Nguyen Khanh T , Moorman Richard , Kuykendall Virginia ,   Collaborators:, Bura L , Erbe E E , Essig K , Galoux I M , Gentry G M , Kersten S , Kho C C , Kim C -H , Kumar G S , Lisowski G T , Manso D L , Ochieng C D , Ritland C , Sriplarich C , Sundquist D L , Tam K C , Vaida M , Weiping G
Published: February 2020

abstract

Nineteen collaborating laboratories (including the authors') analyzed 6 blind, duplicate pairs of various technical materials, pyrethrum extracts, concentrates, and finished products by split injection capillary gas chromatography (GC) with flame ionization detection. This procedure simultaneously quantitates with speed, ease, accuracy, and precision all 6 insecticidal compounds in pyrethrum: pyrethrin I, jasmolin I, cinerin I, pyrethrin II, jasmolin II, and cinerin II, as well as butylcarbityl 6-propylpiperonyl ether (BPE, the predominant compound in technical piperonyl butoxide, also commonly known as piperonyl butoxide) and both the endo and exo isomers of N-octyl bicycloheptene dicarboximide (MGK 264). Repeatability ranged from 4.28 to 7.22% for total pyrethrins, from 2.41 to 7.04% for BPE, and from 2.20 to 4.91 % for total MGK 264. Reproducibility ranged from 5.22 to 9.71 % for total pyrethrins, from 4.37 to 7.04% for BPE, and from 2.66 to 6.01 % for total MGK 264. The capillary GC method for these insecticidal compounds in technical materials, concentrates, and finished products has been adopted first action by AOAC INTERNATIONAL.
Simple System for Rapid Determination of Carbon Dioxide Evolution Rates
Authors: Hsieh Yuch-Ping , Hsieh Yun-Hwa P
Published: February 2020

abstract

Measurement of CO2 evolution rates is important and necessary for many biological investigations because the rate is a common indicator of biological activity. The CO2 evolution rate of a sample can be determined quickly and sensitively with an IR CO2 analyzer. Many existing systems for determining CO2 evolution rates are quite complicated and expensive. They usually require removal of moisture in the testing air stream and a special gas mixture for calibration. The switching devices that allow analysis of multiple samples sequentially also further complicate the system. We present here a simple system—constructed from a commercially available CO2 analyzer and simple laboratory supplies— that analyzes CO2 evolution rates of multiple samples sequentially without special calibration gas mixtures or preremoval of moisture in the testing gas. The sensitivity and measuring range of the system can be conveniently adjusted by varying the sizes of the sample and the sample bottle. The lower detection limit of the system is 1.5 μl_/h, and the testing range is from 2 to 500 μL/h. The system is also portable for field applications.
Compound-Specific Gas Chromatographic/Mass Spectrometric Analysis of Alkylated and Parent Poly cyclic Aromatic Hydrocarbons in Waters, Sediments, and Aquatic Organisms
Authors: Means Jay C
Published: February 2020

abstract

Polycyclic aromatic hydrocarbons (PAHs) and their alkylated and heterocyclic analogs are ubiquitous contaminants in aquatic environments, including estuaries and marine systems. Methodology for compound-specific analysis of 63 parent, alkylated, and heterocyclic PAHs using gas chromatography/ mass spectrometry (GC/MS) in both scanning and selected-ion monitoring modes has been developed and applied to sediment, natural waters and effluents, and marine organisms including oysters, mussels, and fish. Relative response factors and relative retention times for the 63 alkylated, heterocyclic, and parent PAHs compared with 6 deuterated PAHs are given. Analyses of natural sea water samples, enriched at concentrations ranging from 5 to 100 ng/L, show good accuracy (8℅ mean difference at the 5 ng/L level) and precision (mean RSD of 9℅), and method detection limits are in the partsper- trillion range. Results for sediments and tissues of aquatic organisms exposed to petroleum contamination demonstrate that analysis of parent PAHs alone vastly underestimates levels in sediments and tissues and the potential toxic effects of such residues in food webs. Multiple analyses of a reference tissue material show good precision (mean RSD of 15℅) and accuracy (mean difference of 17℅) for both alkylated and parent PAHs.
Simplification of Analytical Methods in Pesticide Residue Analysis by Liquid Chromatography/Electrospray Ionization Mass Spectrometry and Tandem Mass Spectrometry
Authors: Stout Steven J , daCunha Adrian R , Picard Gerald L , Safarpour Maximilian M
Published: February 2020

This report presents a historic, scientific, and economic overview of why mass spectrometry (MS) is rapidly becoming a routine detector for trace analysis of pesticide residues in the regulatory area. Liquid chromatography/electrospray ionization MS and tandem MS dramatically simplify cleanup procedures, reducing not only sample analysis time, but even more important, method development time. Examples include direct determination of imidazolinones in water at 1 ppb, determination of imazethapyr and its metabolites in crop commodities, and determination of imazethapyr in soil.
Simultaneous Determination of Chloramphenicol, Florfenicol, and Thiamphenicol Residues in Milk by Gas Chromatography with Electron Capture Detection
Authors: Pfenning Allen P , Madson Mark R , Roybal José E , Turnipseed Sherri B , Gonzales Steve A , Hurlbut Jeffrey A , Salmon Garrett D
Published: February 2020

A gas chromatographic (GC) method is described for determining residues of chloramphenicol (CAP), florfenicol (FF), and thiamphenicol (TAP) in raw milk, with meta-nitrochloramphenicol (mCAP) as internal standard. Milk is extracted with acetonitrile, centrifuged, evaporated, reconstituted in water, and passed through a C18 solid-phase extraction (SPE) column. The SPE column is eluted with 60℅ methanol, and then the eluate is evaporated and derivatized with Sylon BFT {N,0-bis(trimethylsilyl) trifluoroacetamide [BSTFA]-trimethylchlorosilane [TMCS], 99 + 1}. After derivatization, toluene is added directly to the sample, followed by water, to quench the derivatization process. After centrifugation, the organic layer is carefully removed. Analytes are determined by GC with electron capture detection (ECD). Milk was fortified with fenicols (the collective name for CAP, FF, and TAP) at 5,10, 20, 40 and 80 ng/mL (target level = 10 ng/mL). Overall recoveries were 92,100, and 104℅ for CAP, FF, and TAP, respectively. Overall interassay (betweenday) variabilities were 6.1, 6.7, and 6.0℅ for CAP, FF, and TAP, respectively. Raw milk samples containing incurred residues of FF were also analyzed.
Determination of the Fusarium Mycotoxins Nivalenol, Deoxynivalenol, 3-Acetyldeoxynivalenol, and 15-0-Acetyl-4-deoxynivalenol in Contaminated Whole Wheat Flour by Liquid Chromatography with Diode Array Detection and Gas Chromatography with Electron Capture Detection
Authors: Walker Frank , Meier Barbara
Published: February 2020

A rapid and sensitive method was developed for simultaneous detection of nivalenol (NIV), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-A-DON), and 15-O-acetyl-4-deoxynivalenol (15-A-DON) in wheat flour. Samples were extracted with acetonitrilewater (84 + 16), and the extract was filtered and purified by a column containing a combination of charcoal, celite, and other adsorbents. For screening analysis, the column eluate was only extracted with ethyl acetate. After evaporation of the solvent, the dried residue was redissolved in acetonitrilewater (2 + 8) and then analyzed by reversed-phase liquid chromatography (LC) with diode array detection. Recoveries of NIV, DON, 3-A-DON, and 15-ADON from whole wheat flour spiked at 2 levels were 49-55, 92-97,98-100, and 100-105℅, respectively. To quantitate mycotoxin amounts lower than 1 ppm, purified column extracts were evaporated to dryness, derivatized with heptafluorobutyric anhydride, and analyzed by gas chromatography with electron capture detection (GC-ECD). Average recoveries of NIV, DON, 3-A-DON, and 15-A-DON from whole wheat flour spiked at 2 levels, were 45- 52, 91-103, 81-85, and 84-92℅, respectively. GCECD detection limits for all mycotoxins tested at a signal-to-noise ratio of 4:1 were ˂30 ng/g. Results of GC-ECD analysis for whole wheat flour samples spiked with mycotoxins at 3 and 10 ppm compared well with results (2.8 and 9.9 ppm) for the same samples analyzed by LC.
Determination of Salicin and Related Compounds in Botanical Dietary Supplements by Liquid Chromatography with Fluorescence Detection
Authors: Luo Wenhong , Ang Catharina Y W , Schmitt Thomas C , Betz Joseph M
Published: February 2020

A sensitive and reliable method is described for quantitative determination of salicin (including salicyl alcohol) and salicylic acid in botanical dietary supplements by reversed-phase liquid chromatography (LC) with wavelength-programmed fluorescence detection. One gram sample material was extracted with 20 mL aqueous phosphate buffer (pH 5.0), which was heated in an 80C water bath for 30 min. After centrifugation and cooling of the extract to room temperature, the supernatant was diluted with additional buffer. A1 mL portion of diluted extract was mixed with 1 mL β-glucosidase solution (2 mg/mL) and incubated for 40 min in a 37C water bath. The extract was passed through a 0.45 μm syringe filter and analyzed by LC. Limits of quantitation for salicin and salicylic acid were 20 and 1 μg/g, respectively. Recoveries from samples fortified with salicin at 20,100, and 1000 μg/g and with salicylic acid at 5, 20, and 50 μg/g ranged from 85 to 110℅, with standard deviations less than 7℅.
Analysis of Sulfonylurea Herbicides in Soil Water at Sub-Part-Per-Biffion Levels by Electrospray Negative Ionization Mass Spectrometry Followed by Confirmatory Tandem Mass Spectrometry
Authors: Bossi Rossana , Koppen Benny , Spliid Niels Henrik , Streibig Jens C
Published: February 2020

Liquid chromatography coupled to mass spectrometry (MS) with an electrospray ionization interface was used to analyze 4 sulfonylurea herbicides: chlorsulfuron, metsulfuron-methyl, thifensulfuron-methyl, and tribenuron-methyl. Fortified soil water was acidified to pH 4.5 (the pH was maintained neutral for tribenuron-methyl because it rapidly hydrolyzes at low pH) and extracted on Ci8 cartridges. Extracts were cleaned up on silica cartridges. MS analysis was accomplished by selected ion monitoring of the deprotonated molecular ion in negative-ion mode. The 4 compounds were quantitated with the external standard technique based on the integrated abundance of the molecular ion [M - H]~. Good reproducibility and high sensitivity (detection limits for the 4 compounds were between 0.002 and 0.005 μg/L) were achieved. Tandem MS (MS/MS) in selected reaction monitoring mode on a characteristic product ion (m/z139 for chlorsulfuron, metsulfuron-methyl, and thifensulfuron-methyl; nvzA53 for tribenuronmethyl) was used as confirmatory method. High sensitivity was maintained also with MS/MS, making it possible to identify sulfonylurea herbicides at very low concentrations.
Liquid Chromatographic Determination of Flumequine, Nalidixic Acid, Oxolinic Acid, and Piromidic Acid Residues in Catfish (Ictalurus punctatus)
Authors: Munns Robert K , Turnipseed Sherri B , Pfenning Allen P , Roybal Jose E , Holland David C , Long Austin R
Published: February 2020

A peer-verified, liquid chromatographic (LC) method for simultaneous determination of residues of flumequine (FLU), nalidixic acid (NAL), oxolinic acid (OXO), and piromidic acid (PIR) in catfish muscle is presented. Sample workup involves homogenizing tissue with acetone, defatting with hexane, and extracting quinolones into chloroform. Sample is purified further by partitioning into base and then subsequently back-extracting into chloroform after acidifying the aqueous phase. After solvent is evaporated, the residue is diluted with mobile phase, and analytes are introduced into an LC system where separations are made with a 5 |am, reversed- phase polymer column and an isocratic, buffered acetonitrile- tetrahydrofuran mobile phase. Determinations are made by UV detection at 280 nm for PIR and by fluorescence detection (excitation at 325 excitation and emission at 365 nm) for the other 3 analytes. Each quinolone was used to fortify catfish muscle at 5, 10, 20, 40, and 80 ng/g. The following recoveries and relative standard deviation (RSD) values represent an average of the 5 levels for each analyte: FLU, 79.7℅ (RSD = 5.7℅); OXO, 80.8℅ (RSD = 6.3℅); PIR, 75.0℅ (RSD = 5.9℅); andNAL, 87.1℅ (RSD = 10%). Assay of 5 levels (base incurred catfish, plus 4 dilutions with control catfish) of catfish muscle incurred with the 4 quinolones gave the following averages: FLU: base, 198 ng/g (RSD = 2.3℅); dilutions, 98.0 ng/g (RSD = 4.2℅), 61.6 ng/g (RSD = 4.4℅), 21.6 ng/g (RSD = 2.8℅), 9.24 ng/g (RSD = 8.7℅); OXO, base, 257 ng/g (RSD = 6.9℅); dilutions, 146 ng/g (RSD = 5.5℅), 95.0 ng/g (RSD = 4.1℅), 30.7 ng/g (RSD = 3.8%), 13.7 ng/g (RSD = 4.6%); PIR, base, 22.1 ng/g (RSD = 4.2%); dilutions, 13.7 ng/g (RSD = 6.7℅), 6.49 ng/g (RSD = 15℅), 2.65 ng/g (RSD =15℅); and NAL, base, 75.1 ng/g (RSD = 3.8℅); dilutions, 42.3 ng/g (RSD = 5.1℅), 24.1 ng/g (RSD = 6.3℅), 8.59 ng/g (RSD = 4.8℅). A second multiresidue analysis of the 4 quinolones was performed by an outside analyst. Average recoveries from catfish fortified at 5, 10, 20, and 40 ng/g were FLU, 75.9℅ (RSD = 4.0℅); OXO, 84.0℅ (RSD = 5.5℅); NAL, 85.6℅ (RSD = 8.9℅); and PIR, 66.2℅ (RSD = 8.7℅).
Determination of Fluoride in Bovine Urine
Authors: Osheim David L , Rasmusson Mary C
Published: February 2020

Fluoride concentration in bovine urine is determined by using a selective ion electrode. Urine is buffered and measured against known fluoride (F) standards. The method is applicable to 2 to 40 mg F/L without further dilution. Typical normal urine contains less than 10 mg F/L. Concentrations greater than 10 mg/L support a clinical diagnosis of fluorosis in cattle. Repeatability coefficient of variation (CV) ranged from 1.6 to 3.5℅ for F concentrations of 3.2-13 mg/L. Reproducibility CV ranged from 0.3 to 7.3℅ for F concentrations of 7.0-17.2 mg/L.
Thin-Layer Chromatographic Determination of Monensin in Feeds: Screening Method
Authors: Landgraf Wynne W , Ross P Frank
Published: February 2020

Monensin is extracted from feed with methanol and purified by solvent-partitioning solid-phase extraction. After solvent reduction, monensin is separated by thin-layer chromatography on silica gel and visualized by color development with vanillin. No false-positive results were obtained in validation studies by submitting or peer laboratories when blank samples were analyzed. Three of 20 samples spiked with 5 ppm monensin were reported as containing no monensin. All samples spiked with 10 ppm monensin were reported positive for monensin.
Determination of Fat in Olestra-Containing Savory Snack Products by Capillary Gas Chromatography
Authors: Schul David , Tallmadge Daniel , Burress Derek , Ewald Deborah , Berger Belinda , Henry David
Published: February 2020

A quantitative method to determine fat in olestra-containing savory snack products was validated within the AOAC Peer-Verified Methods Program. The method may be used to demonstrate compliance with the guidelines of the U.S. Nutrition Labeling and Education Act for labeling products as "fat free" or "low fat." The method can measure total and saturated fat in savory snacks when present at levels of 0.2-10 g total fat and 0.1-3 g saturated fat per 30 g serving. The method is standardized to measure C6- C24 fatty acids. Extraction of olestra-containing savory snack samples with chloroform-methanol (modified AOAC Official Method 983.23) yields a lipid extract containing the total fat and olestra. The extracted lipid is hydrolyzed by lipase, yielding fatty acids and unreacted olestra. The fatty acids are precipitated as calcium soaps. Olestra is extracted from insoluble soaps with hexane and then discarded. The isolated soaps are converted back into fatty acids with hydrochloric acid and extracted with hexane. The isolated fatty acids are converted to methyl esters with boron trifluoride-methanol and quantitated by capillary gas chromatography using internal standard. Test samples were prepared by blending olestra-containing and full-fat (triglyceride) snacks to obtain 6 levels of spiking (0-10 g total fat added/30 g serving) in potato chips, potato crisps, cheese puffs, and nacho cheese-flavored corn chips. Results were linear (r2 > 0.997) between 0 and 10 g fat/30 g serving for each product matrix. Mean recovery was 101 6% standard deviation (SD) for total fat and 104 ± 6% SD for saturated fat. Mean recovery by peer laboratory was 88 ± 5% SD for total fat and 95 ± 4% SD for saturated fat in potato chips (0-3 g total fat added/30 g serving). Two sets of 10 replicates of potato chips (0.5 g total fat/30 g serving and 0.16 g saturated fat/30 g serving) and potato crisps (0.5 g total fat/30 g serving and 0.16 g saturated fat/30 g serving) were analyzed by submitting and peer laboratories. Repeatability relative standard deviations ranged from 3.90 to 7.33% for total fat and from 4.01 to 11.53% for saturated fat. Reproducibility relative standard deviations were 7.33% (total fat, potato chips), 7.15% (total fat, potato crisps), 11.36% (saturated fat, potato chips), and 13.50% (saturated fat, potato crisps)
Determination of Chromium in Wine and Other Alcoholic Beverages Consumed in Spain by Electrothermal Atomic Absorption Spectrometry
Authors: Lendinez Elena , Carmen Lopez M , Cabrera Carmen , Luisa Lorenzo M
Published: February 2020

A reliable and rapid method is described for the determination of chromium in alcoholic beverages by electrothermal atomic absorption spectrometry (ETAAS) after optimization of the temperature-time program for the graphite furnace. Chromium in wines was determined directly without sample pretreatment. Other samples were first mineralized with HN03 and V2O5. The method was validated, and its analytical characteristics were checked. The detection limit was 1 pg (for a sample volume of 10 μL). Accuracy was 99.20 ± 3.80% for wines and 98.90 ± 2.00% for other beverages. Precision ranged from 3.50 to 4.50%. The proposed method was applied to 124 samples of alcoholic beverages frequently consumed in Spain. Mean values obtained (μg/L) were 20.28 for wines, 8.75 for beer, 7.85 for cider, 14.60 for brandy, 7.50 for rum, 10.25 for whisky, 8.80 for gin, 9.25 for vodka, 24.45 for anisette, and 10.08 for liquors. The advantages of the proposed method (rapidity, sensitivity) and versatility) make it useful for routine analyses and for estimations of dietary intake of chromium
Expert System for Catalytic Titrimetry—Part 2: Determination of Monobasic Carboxylic Acids
Authors: Abramovic Biljana F , Abramovic Borislav K , Gaál Ferenc F , Obradovtc Danilo M
Published: February 2020

An expert system (ES) to solve the problem of choosing a catalytic titrimetric procedure for determining monobasic carboxylic acids is described. Carboxylic acids were divided into 3 groups—aliphatic, aromatic, and α-aminocarboxylic acids— based on their behavior in catalytic titrations with different indicator reactions, titrant, and/or solvent and the possibility of their selective determination in the presence of other acids
Improved Parameterization of Fertilizer Particle Size Distribution
Authors: Perfect Edmund , Xu Qiang , Terry David L
Published: February 2020

Particle size distribution is an important physical property of granular fertilizers that influences their bulk behavior (e.g., packing and segregation). Several parameter systems for fertilizer particle size distributions are analyzed in this paper. The most common system used by the fertilizer industry is the SGN-UI system, where SGN is the size guide number (the median particle size) and Ul is the uniformity index (the 10th percentile particle size expressed as a percentage of the 95th percentile particle size). This 2-parameter system, however, has many limitations. For example, it does not give a distribution function. Furthermore, the Ul parameter does not accurately reflect the spread of particle sizes. It is therefore necessary to find a better parameterization system. Three size distribution functions (the log-normal, the Rosin-Rammler and the Gaudin-Schuhmann equations) were tested on a size distribution database composed of 377 samples from 7 fertilizer materials. Each function was fitted to the data by nonlinear regression. The Rosin-Rammler function is the best parameter system on the basis of an analysis of variance of the sum of squares of error from the nonlinear fits. Comparisons between the Rosin-Rammler and the SGN-UI parameters were also made. The Rosin- Rammler system is more accurate than the SGN-UI system, possesses the ability of prediction, and provides a measure of the goodness of fit. Therefore, the Rosin-Rammler system should be used to characterize size distribution of granular fertilizer materials instead of the SGN-UI system.
Detection of Thiazide-Based Diuretics in Equine Urine by Liquid Chromatography/Mass Spectrometry
Authors: Garbis Spiros D , Hanley Luke , Kalita Shelley
Published: February 2020

Thiazide-based diuretics are included in the list of banned drugs in the horse-racing industry. One effect of their misuse is increased urine flow, contributing to dilution of other doping agents. Their determination is essential in ensuring compliance to horse-racing regulation. This study evaluates the feasibility of using liquid chromatography/mass spectrometry (LC/MS) with electrospray and atmospheric pressure chemical ionization interfaces to analyze thiazidic diuretics in equine urine samples. Existing LC and gas chromatography/MS methods are limited in their applicability to thiazide analysis. Sample preparation, analyte extraction, chromatographic separation, ion-source collision induced dissociation, solvent composition, ionization mode, and ion polarity are discussed. The practicality of LC/MS for this analysis is demonstrated with actual equine administration samples collected at specified time intervals. Detection limits were 270 ng/mL for chlorothiazide, 131 ng/mL for hydrochlorothiazide, and 384 ng/mL for trichlormethiazide
Liquid Chromatographic Determination of Histamine in Fish, Sauerkraut, and Wine: Interlaboratory Study
Authors: Beljaars Paul R , Van Dijk Remmelt , Onker Klaas M , Schout Louis J ,   Collaborators:, Brans G , Boomkamp J , Bosman J C , van Dijk R , de Jeu C , Krekelberg C , v d Luitgaarden A , Sens C , v d Weert R , Wijma E
Published: February 2020

An interlaboratory study of the liquid chromatographic (LC) determination of histamine in fish, sauerkraut, and wine was conducted. Diminuted and homogenized samples were suspended in water followed by clarification of extracts with perchloric acid, filtration, and dilution with water. After LC separation on a reversed-phase C18 column with phosphate buffer (pH 3.0)-acetonitrile (875 + 125, v/v) as mobile phase, histamine was measured fluorometrically (excitation, 340 nm; emission, 455 nm) in samples and standards after postcolumn derivatization with ophthaldialdehyde (OPA). Fourteen samples (including 6 blind duplicates and 1 split level) containing histamine at about 10- 400 mg/kg or mg/L were analyzed singly according to the proposed procedure by 11 laboratories. Results from one participant were excluded from statistical analysis. For all samples analyzed, repeatability relative standard deviations varied from 2.1 to 5.6%, and reproducibility relative standard deviations ranged from 2.2 to 7.1%. Average recoveries of histamine for this concentration range varied from 94 to 100%
Determination of Maleic Hydrazide in Pesticide Formulations by Capillary Electrophoresis
Authors: Kubilius Donna T , Bushway Rodney J
Published: February 2020

A capillary electrophoresis method was developed to quantitate the growth regulator maleic hydrazide (MH) in pesticide formulations. Liquid formulations were dissolved in water, injected into a capillary electrophoresis instrument, and monitored at 220 nm. The running buffer was 10 mM dibasic sodium phosphate at pH 9.0. Total analysis time was 10 min. Four liquid formulations with a guarantee of 30.2 or 30.3% potassium salt of MH were analyzed. Within-day coefficients of variation (CVs) ranged from 3.0 to 7.7%, and between-day CVs ranged from 5.5 to 10.0%. Purity of each MH peak was checked by using a photodiode array detector in the spectrum mode. No interferences were observed.
Multiresidue Liquid Chromatographic Method for Determining Residues of Mono- and Dibasic Penicillins in Bovine Muscle Tissues
Authors: Boison Joe O , Keng Lily J -Y
Published: February 2020

A liquid chromatographic method with UV detection at 325 nm was developed for simultaneous determination of amoxicillin, ampicillin, penicillin G, and cloxacillin residues in bovine muscle tissue as their mercaptide derivatives. The penicillins are extracted from bovine tissues with 0.1 M phosphate buffer (pH 8.5), cleaned up on a t-C18 Sep-Pak cartridge, and eluted with 2 ml acetonitrile. After the acetonitrile in the eluate is evaporated to dryness, the residue is dissolved in 200 |µL (40 + 60, v/v) aceton itrile-phosphate buffer (pH 6.5) and derivatized with acetic anhydride and mercuric chloride in the presence of 1,2,4-triazole at 65°C for 30 min. Gradient analysis on a Spherisorb 5 µm ODS(2) (octadecyl silane) analytical column using a binary mobile phase consisting of acetonitrile and 0.10M phosphate buffer (pH 6.5) in the presence of 0.0157M sodium thiosulfate at 1 mL/min permits determination of each intact penicillin in bovine muscle tissue at ≥10 ppb with recoveries ≥72%. This laboratory method provides detection sensitivities equivalent to those of rapid tests used for screening β-lactam drug residues in bovine tissue samples for regulatory enforcement.
Determination of Apramycin in Swine Kidney Tissue by Liquid Chromatography with Fluorescence Detection
Authors: Sweeney Daniel J , Coleman Mark R
Published: February 2020

A liquid chromatographic method for determining apramycin in swine kidney tissue is described. Apramycin is extracted from tissue with basic methanol and purified by ion-pair extraction. By using an automated derivatization and injection procedure, the purified extract is derivatized with ophthaldehyde, separated on a C18 column, and detected with a fluorescence detector. For fortified kidney samples, between-run coefficients of variation ranged from 4.8 to 7.1 % at 1.00 ppm and from 9.6 to 14.3% at 0.50 ppm. Recoveries ranged from 76 to 86%. Standard curves were linear over the range 10-100 ng/mL.
Variability Associated with Testing Shelled Corn for Fumonisin
Authors: Whitaker Thomas B , Trucksess Mary W , Johansson Anders S , Geesbrecht Francis G , Hagler Winston M , Bowman Daryl T
Published: February 2020

Variances associated with sampling, sample preparation, and analytical steps of a test procedure that measures fumonisin in shelled corn were estimated. The variance associated with each step of the test procedure increases with fumonisin concentration. Functional relationships between variance and fumonisin concentration were estimated by regression analysis. For each variance component, functional relationships were independent of fumonisin type (total, B1, B2, and B3 fumonisins). At 2 ppm, coefficients of variation associated with sampling (1.1 kg sample), sample preparation (Romer mill and 25 g subsample), and analysis are 16.6,9.1, and 9.7%, respectively. The coefficient of variation associated with the total fumonisin test procedure was 45% and is about the same order of magnitude as that for measuring aflatoxin in shelled corn with a similar test procedure.