bluuebunny/crossref_metadata_2025 huggingface dataset:
Competitive Inhibition ELISA for Quantification of Ara h 1 and Ara h 2, the Major Allergens of Peanuts
Authors: Schmitt David A , Cheng Hsiaopo , Maleki Soheila J , Burks A Wesley
Published: February 2020

Allergies to peanuts are becoming an increasingly important health problem as a result of the persistence and severity of the reaction in allergic individuals. Because no treatment currently is available, avoidance is the only option for peanut-allergic individuals. Avoidance of an abundant and often disguised food such as peanuts, however, is very difficult; therefore, competitive inhibition ELISAs were developed to detect and quantitate each of the major peanut allergens, Ara h 1 and Ara h 2. Under optimal conditions for each assay, the sensitivity of the Ara h 1 and Ara h 2 detection assays were 12 and 0.5 ng/mL, respectively. These assays were primarily devised to effectively compare the levels of Ara h 1 and Ara h 2 in a wide variety of peanuts or peanut products but can also be used to identify cross-reactive antigens. The method is simple and rapid, requiring only one allergen-specific antibody and, therefore, could be adapted specifically to detect the presence of these individual allergens in different foods.
Furan Precursors in Food: A Model Study and Development of a Simple Headspace Method for Determination of Furan
Authors: Becalski Adam , Seaman Stephen
Published: February 2020

Furan was previously detected in foods that had undergone thermal treatment. Because furan is now classified as a possible human carcinogen, a model system was developed to investigate the origins of furan. Also, a simple, rapid isotope dilution (d4-furan) headspace method was developed to measure furan. Two pathways of furan formation have been identified in the model systems tested so far. The first is the oxidation of polyunsaturated fatty acids at elevated temperatures, and the second is linked to the decomposition of ascorbic acid derivatives. The analytical procedure, based on the use of a 50 μL injection (from the headspace of a 1.5 mL vial containing 0.5 mL water) into the split/splitless injection port of a gas chromatograph/mass spectrometer (electron ionization, selected-ion monitoring), showed linearity in the 10–1000 ng/g range with a limit of detection of 1 ng/g.
Single Laboratory Validation of a Method for the Determination of Hydroxymethylfurfural in Honey by Using Solid-Phase Extraction Cleanup and Liquid Chromatography
Authors: Driffield Malcolm , Chan Danny , Macarthur Roy , MacDonald Susan , Brereton Paul , Wood Roger
Published: February 2020

A method is described for the determination of hydroxymethylfurfural (HMF) in honey. The method, which is based on solid-phase extraction cleanup followed by liquid chromatography (LC) with UV absorbance detection, was tested on a variety of different honey types: liquid, set, blended, filtered, crystalline, and comb honey. A sample of honey fortified with a known amount of HMF acted as an in-house reference material. LC with diode-array detection showed that the HMF peak did not contain any peaks of coeluting interfering species. Stability studies showed that honey samples should not be repeatedly frozen and thawed because the temperature changes caused a gradual increase in the HMF concentration. It was also shown that aqueous HMF standard solutions should be kept in the dark at 4°C to avoid degradation of the HMF. The method was internally validated, and the measurement uncertainty was estimated to be ±9.0 at 40 mg/kg, the legal limit. A comparison of the relative standard uncertainty with the Horwitz relative standard deviation showed that the method was suitable for its purpose and should be validated by a collaborative trial.
Acrylamide Formation in Food: A Mechanistic Perspective
Authors: Yaylayan Varoujan A , Stadler Richard H
Published: February 2020

Earliest reports on the origin of acrylamide in food have confirmed asparagine as the main amino acid responsible for its formation. Available evidence suggests that sugars and other carbonyl compounds play a specific role in the decarboxylation process of asparagine, a necessary step in the generation of acrylamide. It has been proposed that Schiff base intermediate formed between asparagine and the sugar provides a low energy alternative to the decarboxylation from the intact Amadori product through generation and decomposition of oxazolidin-5-one intermediate, leading to the formation of a relatively stable azomethine ylide. Literature data indicate the propensity of such protonated ylides to undergo irreversible 1,2-prototropic shift and produce, in this case, decarboxylated Schiff bases which can easily rearrange into E Decarboxylated Amadori products can either undergo the well known β-elimination process initiated by the sugar moiety to produce 3-aminopropanamide and 1-deoxyglucosone or undergo 1,2-elimination initiated by the amino acid moiety to directly generate acrylamide. On the other hand, the Schiff intermediate can either hydrolyze and release 3-aminopropanamide or similarly undergo amino acid initiated 1,2-elimination to directly form acrylamide. Other thermolytic pathways to acrylamide—considered marginal at this stage—via the Strecker aldehyde, acrolein, and acrylic acid, are also addressed. Despite significant progress in the understanding of the mechanistic aspects of acrylamide formation, concrete evidence for the role of the different proposed intermediates in foods is still lacking.
Stability-Indicating Methods for Determination of Pyritinol Dihydrochloride in the Presence of Its Precursor and Degradation Product by Derivative Spectrophotometry
Authors: Shehata Mostafa A , El-Sayed Mohammad A , El-Bardicy Mohammad G , El-Tarras Mohammad F
Published: February 2020

A first-derivative spectrophotometric (1D) method and a derivative-ratio zero-crossing spectrophotometric (1DD) method were used to determine pyritinol dihydrochloride (I) in the presence of its precursor (II) and its degradation product (III) with 0.1N hydrochloric acid as a solvet. Linear relationships were obtained in the ranges of 6–22 μg/mL for the (1D) method and 6–20 μg/mL for the (1DD) method. By applying the proposed methods, it was possible to determine pyritinol dihydrochloride in its pure powdered form with an accuracy of 100.36 ± 1.497% (n = 9) for the (1D) method and an accuracy of 99.92 ± 1.172% (n = 8) for the (1DD) method. Laboratory-prepared mixtures containing different ratios of (I), (II), and (III) were analyzed, and the proposed methods were valid for concentrations of ≤10% (II) and ≤50% (III). The proposed methods were validated and found to be suitable as stability-indicating assay methods for pyritinol in pharmaceutical formulations.
Confirmation of Synthetic Glucocorticoids with Liquid Chromatography/Mass Spectrometry: Organization and Results of an International Interlaboratory Comparison Test
Authors: Van den hauwe Olivia , Campbell Katrina , Crooks Steven R H , Schilt Robert , Van Peteghem Carlos H
Published: February 2020

Within the framework of a European Union (EU) research project entitled “Food Safety Screening: Synthetic Glucocorticoids (QLK1-1999-00122),” an international interlaboratory ring test was organized to compare and evaluate different liquid chromatography/mass spectrometry (LC/MS) confirmatory methods that are applied in European monitoring programs for detecting the use of synthetic glucocorticoids. Liver and urine samples of bovines treated with synthetic glucocorticoids were collected and sent to the participants of the study for analysis. Participants received 3 liver and 3 urine samples and were free to use either their own LC/MS method or an LC/MS-based method developed during the EU research project. The residue concentrations in the samples were calculated as the mean of the concentrations reported by each laboratory. The mean dexamethasone concentration of liver sample L1 was calculated as 2.27 μg/kg [relative standard deviation (RSD) 43%, n = 9], which exceeds the maximum residue level (MRL) of 2 μg/kg. Three of the 9 laboratories (33%) reported concentration levels less than 2 μg/kg, resulting in obviously false compliant results. The overall mean concentration of flumethasone in liver sample L2 was calculated as 3.27 μg/kg (RSD 33%, n = 8). Applying a comparable limit for flumethasone of 2 μg/kg, 8 of the 9 laboratories would have obtained a correct noncompliant result. As for the blank liver sample, 1 participant found a false noncompliant result. The urine sample U1 contained prednisolone residues at a mean concentration of 1.58 μg/kg (RSD 43%, n = 9). Four out of 9 results were less than a theoretical minimum required performance level (MRPL) of 2 μg/kg. The calculated concentration of dexamethasone in urine sample U3 was 5.21 μg/kg (RSD 62%, n = 9). One of the 9 results was lower than 2 μg/kg. Urine sample U2 was correctly reported as blank by all participants.
Investigation of Pyrrolizidine Alkaloids and Their N-Oxides in Commercial Comfrey-Containing Products and Botanical Materials by Liquid Chromatography Electrospray Ionization Mass Spectrometry
Authors: Altamirano Jorgelina C , Gratz Samuel R , Wolnik Karen A
Published: February 2020

Pyrrolizidine alkaloids (PAs) and their N-oxides are found in several plant families throughout the world. PAs are potentially toxic to the liver and/or lungs in humans and may cause acute liver failure, cirrhosis, pneumonitis, or pulmonary hypertension. PAs are also carcinogenic to animals, and they have been linked to the development of hepatocellular and skin squamous cell carcinomas as well as liver angiosarcomas. According to experimental studies, the quantity of PAs in some herbal teas and dietary supplements is sufficient to be carcinogenic in exposed individuals. A method for the extraction and identification of PAs and their N-oxides in botanical materials and commercial comfrey-containing products has been developed using liquid chromatography electrospray ionization mass spectrometry. Following optimization of the extraction procedure and the chromatographic conditions, the method was applied to the analysis of 10 herbal remedies. All of the products that were labeled to contain comfrey were found to contain measurable quantities of PAs.
Quantification of the 35S Promoter in DNA Extracts from Genetically Modified Organisms Using Real-Time Polymerase Chain Reaction and Specificity Assessment on Various Genetically Modified Organisms, Part I: Operating Procedure
Authors: Fernandez Sophie , Charles-Delobel Chrystèle , Geldreich Angèle , Berthier Georges , Boyer Francine , Collonnier Cécile , Coué-Philippe Géraldine , Diolez Annick , Duplan Marie-Noëlle , Kebdani Naïma , Romaniuk Marcel , Feinberg Max , Bertheau Yves
Published: February 2020

A highly sensitive quantitative real-time assay targeted on the 35S promoter of a commercial genetically modified organism (GMO) was characterized (sF/sR primers) and developed for an ABI Prism® 7700 Sequence Detection System and TaqMan® chemistry. The specificity assessment and performance criteria of sF/sR assay were compared to other P35S-targeted published assays. sF/sR primers amplified a 79 base pair DNA sequence located in a part of P35S that is highly conserved among many caulimovirus strains, i.e., this consensus part of CaMV P35S is likely to be present in many GM events. According to the experimental conditions, the absolute limit of detection for Bt176 corn was estimated between 0.2 and 2 copies of equivalent genome (CEG). The limit of quantification was reached below 0.1% Bt176 content. A Cauliflower Mosaic Virus control (CaMV) qualitative assay targeted on the ORF III of the viral genome was also used as a control (primers 3F/3R) to assess the presence of CaMV in plant-derived products. The specificity of this test was assessed on various CaMV strains, including the Figwort Mosaic Virus (FMV) and solanaceous CaMV strains. Considering the performance of sF/sR quantification test, the highly conserved sequence, and the small size of the amplicon, this assay was tested in a collaborative study in order to be proposed as an international standard.
Determination of Diethanolamine in Shampoo Products Containing Fatty Acid Diethanolamides by Liquid Chromatography with a Thermal Energy Analyzer
Authors: Chou Hardy J
Published: February 2020

A liquid chromatography (LC) method using a thermal energy analyzer (TEA) is described for the determination of diethanolamine (DEA) in shampoo products containing fatty acid diethanolamides. DEA was converted to N-nitrosodiethanolamine (NDELA) by dissolving a portion of the product in 6M acetic acid and mixing with sodium nitrite for 1 h at room temperature. The reaction mixture was dried, dissolved in acetone, and analyzed for NDELA by LC-TEA. The recovery of DEA from 2 shampoo products at fortification levels of 25, 250, and 1000 ppm ranged from 70 to 105%. Twenty shampoo products were analyzed by this method, and 19 were found to contain DEA at levels ranging from 140 to 15 200 ppm.
Use of Buffering and Other Means to Improve Results of Problematic Pesticides in a Fast and Easy Method for Residue Analysis of Fruits and Vegetables
Authors: Lehotay Steven J , Maštovská Kateřina , Lightfield Alan R
Published: February 2020

A modification that entails the use of buffering during extraction was made to further improve results for certain problematic pesticides (e.g., folpet, dichlofluanid, chlorothalonil, and pymetrozine) in a simple, fast, and inexpensive method for the determination of pesticides in produce. The method, known as the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for pesticide residues in foods, now involves the extraction of the sample with acetonitrile (MeCN) containing 1% acetic acid (HAc) and simultaneous liquid–liquid partitioning formed by adding anhydrous MgSO4 plus sodium acetate (NaAc). The extraction method is carried out by shaking a centrifuge tube which contains 1 mL of 1% HAc in MeCN plus 0.4 g anhydrous MgSO4 and 0.1 g anhydrous NaAc per g sample. The tube is then centrifuged, and a portion of the extract is transferred to a tube containing 50 mg primary secondary amine sorbent plus 150 mg anhydrous MgSO4/mL of extract. After a mixing and centrifugation step, the extract is transferred to autosampler vials for concurrent analysis by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/tandem mass spectrometry. Independent of the original sample pH, the use of buffering during the extraction yields pH <4 in the MeCN extract and >5 in the water phase, which increases recoveries of both acid- and base-sensitive pesticides. The method was evaluated for 32 diverse pesticides in different matrixes, and typical percent recoveries were 95 ± 10, even for some problematic pesticides. Optional solvent exchange to toluene prior to GC/MS analysis was also evaluated, showing equally good results with the benefit of lower detection limits, but at the cost of more time, material, labor, and expense.
Evaluation of Two Fast and Easy Methods for Pesticide Residue Analysis in Fatty Food Matrixes
Authors: Lehotay Steven J , Maštovská Kateřina , Yun Seon Jong
Published: February 2020

Two rapid methods of sample preparation and analysis of fatty foods (e.g., milk, eggs, and avocado) were evaluated and compared for 32 pesticide residues representing a wide range of physicochemical properties. One method, dubbed the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for pesticide residue analysis, entailed extraction of 15 g sample with 15 mL acetonitrile (MeCN) containing 1% acetic acid followed by addition of 6 g anhydrous magnesium sulfate and 1.5 g sodium acetate. After centrifugation, 1 mL of the buffered MeCN extract underwent a cleanup step (in a technique known as dispersive solid-phase extraction) using 50 mg each of C18 and primary secondary amine sorbents plus 150 mg MgSO4. The second method incorporated a form of matrix solid-phase dispersion (MSPD), in which 0.5 g sample plus 2 g C18 and 2 g anhydrous sodium sulfate was mixed in a mortar and pestle and added above a 2 g Florisil column on a vacuum manifold. Then, 5 × 2 mL MeCN was used to elute the pesticide analytes from the sample into a collection tube, and the extract was concentrated to 0.5 mL by evaporation. Extracts in both methods were analyzed concurrently by gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry. The recoveries of semi-polar and polar pesticides were typically 100% in both methods (except that basic pesticides, such as thiabendazole and imazalil, were not recovered in the MSPD method), but recovery of nonpolar pesticides decreased as fat content of the sample increased. This trend was more pronounced in the QuEChERS method, in which case the most lipophilic analyte tested, hexachlorobenzene, gave 27 ± 1% recovery (n = 6) in avocado (15% fat) with a <10 ng/g limit of quantitation.
Simultaneous Determination of Methylmercury and Ethylmercury in Rice by Capillary Gas Chromatography Coupled On-line with Atomic Fluorescence Spectrometry
Authors: Shi Jian-Bo , Liang Li-Na , Jiang Gui-Bin
Published: February 2020

A comprehensive method for simultaneous determination of methylmercury (MeHg) and ethylmercury (EtHg) in rice by capillary gas chromatography (GC) coupled on-line with atomic fluorescence spectrometry was developed. The experimental conditions, including the pyrolyzer temperature and flow rates of the make-up gas and sheath gas, were optimized in detail. The absolute detection limits (3σ) were 0.005 ng as Hg for both MeHg and EtHg. The relative standard deviation values (n = 5) for 10 ng Hg/mL of MeHg and EtHg were 2.5 and 1.3%, respectively. The method was evaluated by analyzing 2 certified reference materials (DORM-2 and GBW08508), and the determined values of MeHg and total mercury concentrations were in good agreement with the certified values. In addition, the recoveries of MeHg and EtHg spiked into a rice sample collected from Jiangsu province in China were 86 and 77%, respectively. The proposed method was applied to analysis of MeHg and EtHg in 25 rice samples cultivated in 15 provinces of China. In all samples, MeHg was detectable and no EtHg was found. The MeHg contents in rice samples ranged from 1.9 to 10.5 ng/g, accounting for 7–44% of the total mercury measured.
Quantitative Colorimetric Analysis of Aloe Polysaccharides as a Measure of Aloe Vera Quality in Commercial Products
Authors: Eberendu Alexis R , Luta Gabriela , Edwards Joshua A , Mcanalley Bill H , Davis Brice , Rodriguez Santiago , Ray Henry C
Published: February 2020

Aloe Vera inner leaf gel has been used as a medicinal remedy for many years. Yet some aloe products do not demonstrate beneficial effects, indicating that poor quality products are reaching the market. Therefore, an efficient and accurate method is needed to evaluate the quality of aloe products. This paper describes a quick, quantitative colorimetric assay that has been developed for the determination of glucomannan in aloe gel and products. With this method, interference by non-aloe polysaccharides or other extraneous components was absent or negligible. Data indicate that the glucomannan can be determined at parts per million (mg/L) in aqueous solutions with an accuracy of 100 ± 5% at a 10 mg/L concentration. The correlation coefficient is 0.999, and linearity is from 0.9 to 72.7 mg/L in the test solution. The method is inexpensive, simple, sensitive, and reproducible. This method was applied to determine the polysaccharide content of commercial aloe products. Both qualitative and quantitative information can be obtained in about 5 min.
Determination of “Net Carbohydrates” Using High-Performance Anion Exchange Chromatography
Authors: Lilla Zach , Sullivan Darryl , Ellefson Wayne , Welton Kevin , Crowley Rick
Published: February 2020

For labeling purposes, the carbohydrate content of foods has traditionally been determined by difference. This value includes sugars, starches, fiber, dextrins, sugar alcohols, polydextrose, and various other organic compounds. In some cases, the current method may lack sufficient specificity, precision, and accuracy. These are subsequently quantitated by high performance anion exchange chromatography with pulsed amperometric detection and expressed as total nonfiber saccharides or percent “net carbohydrates.” In this research, a new method was developed to address this need. The method consists of enzyme digestions to convert starches, dextrins, sugars, and polysaccharides to their respective monosaccharide components. These are subsequently quantified by high-performance anion exchange chromatography with pulsed amperometric detector and expressed as total nonfiber saccharides or percent “net carbohydrates.” Hydrolyzed end products of various novel fibers and similar carbohydrates have been evaluated to ensure that they do not register as false positives in the new test method. The data generated using the “net carbohydrate” method were, in many cases, significantly different than the values produced using the traditional methodology. The recoveries obtained in a fortified drink matrix ranged from 94.9 to 105%. The coefficient of variation was 3.3%.
Evaluation of the VIDAS® Listeria (LIS) Immunoassay for the Detection of Listeria in Foods Using Demi-Fraser and Fraser Enrichment Broths, as Modification of AOAC Official Method 999.06 (AOAC Official Method 2004.06)
Authors: Silbernagel Karen M , Jechorek Robert P , Kaufer Amanda L , Johnson Ronald L ,   Collaborators:, Aleo V , Brown B , Buen M , Buresh J , Carson M , Franklin J , Ham P , Humes L , Husby G , Hutchins J , Jechorek R , Jenkins J , Kaufer A , Kexel N , Kora L , Lam L , Lau D , Leighton S , Loftis M , Luc S , Martin J , Nacar I , Nogle J , Park J , Schultz A , Seymore D , Smith C , Smith J , Thou P , Ulmer M , Voss R , Weaver V
Published: February 2020

A multilaboratory study was conducted to compare the VIDAS® LIS immunoassay with the standard cultural methods for the detection of Listeria in foods using an enrichment modification of AOAC Official Method 999.06. The modified enrichment protocol was implemented to harmonize the VIDAS LIS assay with the VIDAS LMO2 assay. Five food types—brie cheese, vanilla ice cream, frozen green beans, frozen raw tilapia fish, and cooked roast beef—at 3 inoculation levels, were analyzed by each method. A total of 15 laboratories representing government and industry participated. In this study, 1206 test portions were tested, of which 1170 were used in the statistical analysis. There were 433 positive by the VIDAS LIS assay and 396 positive by the standard culture methods. A Chi-square analysis of each of the 5 food types, at the 3 inoculation levels tested, was performed. The resulting average Chi square analysis, 0.42, indicated that, overall, there are no statistical differences between the VIDAS LIS assay and the standard methods at the 5% level of significance.
Testing Green Coffee for Ochratoxin A, Part II: Observed Distribution of Ochratoxin A Test Results
Authors: Vargas Eugenia Azevedo , Whitaker Thomas B , dos Santos Eliene Alves , Slate Andrew B , Lima Francisco B , Franca Regina C A
Published: February 2020

The suitability of 4 theoretical distributions (normal, lognormal, negative binomial, and gamma) to predict the observed distribution of ochratoxin A (OTA) in green coffee was investigated. One symmetrical and 3 positively skewed theoretical distributions were each fitted to 25 empirical distributions of OTA test results for green coffee beans. Parameters of each theoretical distribution were calculated by using Methods of Moments. The 3 skewed theoretical distributions provided acceptable fits to each of the 25 observed distributions. Because of its simplicity, the lognormal distribution was selected to model OTA test results for green coffee. Using variance equations determined in previous studies, mathematical expressions were developed to calculate the parameters of the log normal distribution for a given OTA lot concentration and test procedure. Observed acceptance probabilities were compared to an operating characteristic curve predicted from the lognormal distribution, and all 25 observed acceptance probabilities were found to lie within the 95% confidence band associated with the predicted operating characteristic curve. The parameters of compound gamma distribution were used to calculate the fraction of OTA contamination beans within a contaminated lot. The percent-contaminated beans were a function of the lot concentration and increased with lot concentration. At a lot concentration of 5 μg/kg, approximately 6 beans per 10 000 beans are contaminated.
Dietary Protein Quality in Humans—An Overview
Authors: Moughan Paul J
Published: February 2020

The first objective in evaluating protein quality is to permit a ranking of proteins according to their potential nutritive value and to permit detection of changes in nutritive value due to processing and/or storage. The second objective is to permit prediction of the contribution a food protein, or mixture of food proteins, makes toward meeting nitrogen and amino acid requirements for growth or maintenance. Different approaches are used in meeting these distinct aims. The preferred current method to meet the second aim is the protein digestibility corrected amino acid score (PDCAAS). This article introduces the concept of PDCAAS and places it in the context of the series of papers published in this Special Guest Editor Section addressing aspects of dietary amino acid utilization.
The Effect of Hydrolysis Time on Amino Acid Analysis
Authors: Darragh Alison J , Moughan Paul J
Published: February 2020

Determining the amino acid content of a protein involves the hydrolysis of that protein, usually in acid, until the protein-bound amino acids are released and made available for detection. Both the variability in the ease of peptide bond cleavage and differences in the acid stability of certain amino acids can significantly affect determination of a protein's amino acid content. By using multiple hydrolysis intervals, a greater degree of accuracy can be obtained in amino acid analysis. Correction factors derived by linear extrapolation of serial hydrolysis data are currently used. Compartmental modeling of the simultaneous hydrolysis (yield) and degradation (decay) of amino acids by nonlinear multiple regression of serial hydrolysis data has also been validated and applied to determine the amino acid composition of various biological samples, including egg-white lysozyme, human milk protein, and hair. Implicit in the routine application of serial hydrolysis in amino acid analysis, however, is an understanding that correction factors, derived either linearly or through the more accurate nonlinear multiple regression approach, need to be determined for individual proteins rather than be applied uniformly across all protein types.
Validation Assay for Total Flavonoids, as Rutin Equivalents, from Trichilia catigua Adr. Juss (Meliaceae) and Ptychopetalum olacoides Bentham (Olacaceae) Commercial Extract
Authors: Rolim André , Maciel Carolina P M , Kaneko Telma M , Consiglieri Vladi O , Salgado-Santos Idalina M N , Velasco Maria Valéria R
Published: February 2020

An ultraviolet spectrophotometric method was validated for total flavonoid quantitation, as rutin equivalents, present in the Trichilia catigua Adr. Juss (Meliaceae) and Ptychopetalum olacoides Bentham (Olacaceae) commercial extract. Parameters as linearity, interval (range), specificity, estimated limit of detection (LOD, μg/mL), estimated limit of quantitation (LOQ, μg/mL), recovery (R, %), precision or relative standard deviation (RSD, %), and accuracy (E, %) were established. The analytical method was validated according to the experimental results: correlation coefficient (r = 0.9997); interval (RSD = 0.15–0.47%; E = 98.98–101.24%); specificity to total flavonoids quantitation, as rutin equivalents, at wavelength 361.0 nm; LOD = 0.09 μg/mL and LOQ = 0.27 μg/mL; R = 99.36–102.14%; adequate intraand interrun precision (0.30–0.49% and 0.31–0.81%), and intra- and interrun accuracy (100.60–102.38% and 98.58–100.38%).
Determination of Glucosamine in Raw Materials and Dietary Supplements Containing Glucosamine Sulfate and/or Glucosamine Hydrochloride by High-Performance Liquid Chromatography with FMOC-Su Derivatization: Collaborative Study
Authors: Zhou Joseph Ziqi , Waszkuc Ted , Mohammed Felicia ,   Collaborators:, Blumhorst M , Buren R , Das R , Huang L , Jabusch J , Kou X , Nagarajan M , Nguyen H , Orellana K , Peng T S , Podhola B , Ray C , Reif K , Shevchuk C , Solyom A , Sullivan D , Wang J , Wang W , Yang Q , Zheng Q
Published: February 2020

A collaborative study was conducted for determination of glucosamine in raw materials and dietary supplements containing glucosamine sulfate and/or glucosamine hydrochloride by high-performance liquid chromatography (HPLC) with N-(9-fluorenyl-methoxycarbonyloxy) succinimide (FMOC-Su) derivatization. Thirteen blind materials, one pair of which were duplicates, were tested by 12 collaborating laboratories. The test samples consisted of various commercial products, including tablets, capsules, drink mix, and liquids as well as raw materials, blanks, and those for spike recovery analyses. The tests with blank products and products spiked with glucosamine showed good specificity of the method. The average recoveries at spike levels of 100 and 150% of the declared amount were 99.0% with a relative standard deviation (RSD) of 2.1%, and 101% with an RSD of 2.3%, respectively. The test results between laboratories on each commercial product were reproducible with RSD values of no more than 4.0%, and the results were repeatable in the same laboratory with an average RSD of 0.7%. HorRat values ranged from 0.5 to 1.7 on both tests of spike recovery and reproducibility between laboratories on commercial products. The average determination coefficient of the calibration curves from the laboratories was 0.9995 with an RSD of 0.03%. All of the 12 collaborating laboratories succeeded in the study and none of their reported test results were outliers, partly indicating the robustness of the method. It is recommended that the method be accepted by AOAC INTERNATIONAL as Official First Action.
Capillary Electrophoresis Method for Fexofenadine Hydrochloride in Capsules
Authors: Breier Ana R , Garcia Sílvia S , Jablonski André , Steppe Martin , Schapoval Elfrides E S
Published: February 2020

A simple, accurate, and effective capillary electrophoresis method with ultraviolet absorbance detection was developed and validated for the quantitation of the antihistamine fexofenadine in capsules. The separation was performed with an uncoated fused-silica capillary (47 cm × 75 μm id) and was operated at 20 kV potential. Temperature was maintained at 25°C. The run buffer was prepared with 20mM Na2B4O7 × 10 H2O. Software was used for system control, data acquisition, and analysis. Method validation was performed by evaluation of the analytical parameters linearity, precision, accuracy, limits of detection and quantitation, and specificity. The method was linear (r = 0.9999) at concentrations ranging from 20 to 100 μg/mL, precise (relative standard deviation intra-assay = 1.2, 1.6, and 1.8% and interassay = 1.5%); accurate (recovery = 98.1%); and specific. The limits of detection and quantitation were 0.69 and 2.09 μg/mL, respectively. The method was compared to the liquid chromatography method developed previously by the authors for the same drug, and no significant difference was found between the 2 methods in fexofenadine hydrochloride quantitation.
Determination of β-Carotene in Supplements and Raw Materials by Reversed-Phase High Pressure Liquid Chromatography: Collaborative Study
Authors: Szpylka John , DeVries Jonathan W ,   Collaborators:, Bhandari S , Bui M H , Ji D , Konings E , Lewis R , Maas P , Parish H , Post B , Schierle J , Sullivan; D , Taylor A , Wang J , Ware G , Woollard D , Wu T
Published: February 2020

Twelve laboratories representing 4 countries participated in an interlaboratory study conducted to determine all-trans-β-carotene and total β-carotene in dietary supplements and raw materials. Thirteen samples were sent as blind duplicates to the collaborators. Results obtained from 11 laboratories are reported. For products composed as softgels and tablets that were analyzed for total β-carotene, the reproducibility relative standard deviation (RSDR) ranged from 3.35 to 23.09% and the HorRat values ranged from 1.06 to 3.72. For these products analyzed for trans β-carotene, the reproducibility relative standard deviation (RSDR) ranged from 4.28 to 22.76% and the HorRat values ranged from 0.92 to 3.37. The RSDr and HorRat values in the analysis of a beadlet raw material were substantial and it is believed that the variability within the material itself introduced significant variation in subsampling. The method uses high pressure liquid chromatography (LC) in the reversed-phase mode with visible light absorbance for detection and quantitation. If high levels of α-carotenes are present, a second LC system is used for additional separation and quantitation of the carotene species. It is recommended that the method be adopted as an AOAC Official Method.
Simultaneous Determination of 16 Sulfonamides in Honey by Liquid Chromatography/TandemMass Spectrometry
Authors: Pang Guo-Fang , Cao Yan-Zhong , Zhang Jin-Jie , Jia Guang-Qun , Fan Chun-Lin , Li Xue-Min , Liu Yong-Ming , Li Zeng-Yin , Shi Yu-Qiu
Published: February 2020

A method is described for the determination of 16 sulfonamides in honey. Samples are dissolved in phosphoric acid solution (pH2), cleaned up with 2 solid-phase extraction (SPE) cartridges, an aromatic sulfonic cation-exchange cartridge and an Oasis HLB SPE cartridge, and analyzed both qualitatively and quantitatively by liquid chromatography/tandem mass spectrometry (LC/MS/MS) under the selected conditions. Without exception, calibration curves were linear (r = >0.995), when sulfamethizole was between 1.0 and 25.0 μg/kg; sulfacetamide, sulfapyridine, sulfadiazine, sulfachloropyridazine, sulfamethoxazole, sulfamerazine, sulfisoxazole, sulfamonomethoxine, and sulfadoxine were between 2.0 and 50.0 μg/kg; sulfamethoxypyridazine, sulfadimethoxine, and sulfathiazole were between 4.0 and 100.0 μg/kg; sulfamethazine and sulfameter were between 8.0 and 200.0 μg/kg; and sulfaphenazole was between 12.0 and 300.0 μg/kg. Average recoveries at 4 fortification levels in the range of 1.0–300 μg/kg in honey were 70.9–102.5%, and relative standard deviations were 2.02–11.52%. The limits of quantitation for the 16 sulfonamides were between 1.0 and 12.0 μg/kg, with the LC/MS/MS method.
Determination of Allura Red in Some Food Samples by Adsorptive Stripping Voltammetry
Authors: Alghamdi Ahmad H
Published: February 2020

Square wave (SW) voltammetry was used to explore the adsorption properties of the food additive dye Allura Red on a hanging mercury drop electrode (HMDE). By using the adsorptive stripping voltammetric approach, we developed a sensitive electroanalytical method for the determination of this azo dye. A well-developed voltammetric peak probably related to the cathodic reduction of the azo moiety was obtained in pH 9 Britton-Robinson (B-R) buffer at 613 mV. Cyclic voltammetric studies indicated that the reduction process was irreversible and primarily controlled by adsorption. The adsorptive voltammetric signal was evaluated with respect to various experimental conditions; the optimized values were supporting electrolyte, B-R buffer; pH 11; accumulation time, 180s; accumulation potential, 0.0V; scan rate, 900 mV/s; pulse amplitude, 75 mV; and SW frequency, 90 Hz. Adsorptive voltammetric peak current showed a linear response for Allura Red in the concentration range of 2.5 × 10−8 to 2.0 × 10−7 mol/L (r = 0.998). The limit of detection was 8.5 × 10−9 mol/L (4.2 ng/mL), the precision in terms of relative standard deviation was 1.3%, and the mean recovery was 102%. Possible interferences by several substances usually present in food products such as food additive azo dyes (E110, E102), gelatin, natural and artificial sweeteners, preservatives, and antioxidants were also evaluated. The proposed electrochemical procedure was successfully applied to the determination of this food dye in commercially available candy and a soft drink. The results were compared by statistical evaluation with those obtained by a reference spectrophotometric method.
An Approach to the Application of Microwave-Assisted Micellar Extraction and Liquid Chromatography with Ultraviolet Detection to the Extraction and Determination of Organophosphorus Pesticides in Tomato Samples
Authors: Padrón-Sanz Carolina , Sosa-Ferrera Zoraida , Santana-Rodríguez Jose J
Published: February 2020

Microwave-assisted micellar extraction methodology was applied to extract a mixture of 8 organophosphorus pesticides from the cuticle of tomato samples prior to analysis by liquid chromatography with ultraviolet detection. This technique provided very good results and was simple, fast, and environmentally friendly. The pesticides under study were extracted using the nonionic surfactants polyoxyethylene 10 lauryl ether (POLE) and oligoethylene glycol monoalkyl ether (Genapol X-080). The optimal extraction variables to be applied were determined for each surfactant and then compared. POLE proved to be the most suitable for the extraction, with recoveries over 70% in the majority and relative standard deviation values under 4.8%. After validation using a tomato sample enriched with a certified mixture, the proposed method was applied to the analysis of organophosphorus pesticides in lettuce and pepper samples.
Development and Validation of a Method for Determination of Caffeine in Diuretic Tablets and Capsules by High-Performance Thin-Layer Chromatography on Silica Gel Plates with a Concentration Zone Using Manual Spotting and Ultraviolet Absorption Densitometry
Authors: Sullivan Caitlin , Sherma Joseph
Published: February 2020

A new quantitative method using silica gel high-performance thin-layer chromatography plates with channels and a concentration zone, manual application of standards and samples, development with methanol–ethyl acetate (15 + 85) mobile phase, and ultraviolet absorption densitometry is reported for the determination of caffeine in diuretic pharmaceutical preparations. Tablet and capsule products containing potassium salicylate, acetaminophen, and salicylamide as active ingredients were analyzed to test the applicability of the new method, and precision, accuracy, linearity, limits of detection and quantitation, and selectivity were validated. The milligrams of caffeine in each tablet ranged from 48.0 to 51.0, and the milligrams in each capsule from 37.9 to 40.3. Within-day precision was 1.48 and 1.78% (n = 6), and interday precision 0.723 and 1.26% (n = 5) for analysis of 2 tablets and 2 capsules, respectively. Accuracy validation of the tablet and capsule results produced errors of 1.0 and 1.9% for spiked blank analyses and 2.6 and 3.5% for standard addition analyses, respectively. A comparative study using a caffeine standard solution and a multicomponent analgesic tablet solution containing caffeine, acetaminophen, and acetylsalicylic acid showed that manual application on the concentration zone, instrumental application on the concentration zone, and instrumental application on the silica gel gave quite similar results in terms of number of theoretical plates, resolution, limit of detection, and linearity.
Simultane ous Determination of Protopseudohypericin, Pseudohypericin, Protohypericin, and Hypericin Without Light Exposure
Authors: Baugh Steven F
Published: February 2020

St. John's wort products are commonly standardized to total naphthodianthrones and hyperforin. Determination of these marker compounds is complicated because of the photochemistry of the naphthodianthrones pseudohypericin and hypericin and the instability of hyperforin in solution. Protopseudohypericin and protohypericin have been identified as naturally occurring naphthodianthrones and, when exposed to light, they are converted into pseudohypericin and hypericin, respectively. However, exposure to light and the resulting naphthodianthrone free-radical reactions oxidize hyperforin. A mathematical relationship between the response of the proto compound and the resulting naphthodianthrone can be established by comparing the analytical response of the proto compound in a solution protected from light with the increase in the analytical response of naphthodianthrone in the same solution after exposure to light. By mathematically converting the proto compounds to their respective products, exposure to light can be avoided while still including proto compounds in a single assay. The method presented here details the reporting of all significant naphthodianthrones, including protopseudohypericin and protohypericin, without exposure to light. This approach includes the benefits of improved naphthodianthrone precision and protection of hyperforin from oxidation.
New Methods for Determination of Cinnarizine in Mixture with Piracetam by Spectrodensitometry, Spectrophotometry, and Liquid Chromatography
Authors: Metwally Fadia H , Elzeany B A , Darwish H W
Published: February 2020

Four new methods were developed and validated for the determination of cinnarizine HCl in its binary mixture with piracetam in pure and pharmaceutical preparations. The first one was a densitometric analysis that provides a simple and rapid method for the separation and quantification of cinnarizine HCl. The method depends on the quantitative densitometric evaluation of thin-layer chromatograms of cinnarizine HCl at 252 nm over concentration range of 1–6 μg/spot, with a mean accuracy of 100.05 ± 0.91%. The second method was determination of the drug using a colorimetric method that utilizes the reaction of 3-methylbenzothiazolin-2-one in the presence of FeCl3 as an oxidant. The green color of the resulting product was measured at 630 nm over concentration range 10–40 μg/mL, with a mean accuracy of 100.10 ± 1.13%. The third method was a direct spectrophotometric determination of cinnarizine HCl at 252 nm over the concentration range 7–20 μg/mL, while piracetam was determined by derivative ratio spectrophotometry at 221.6 nm over concentration range 5–30 μg/mL, with a mean accuracy of 100.14 ± 0.79 and 100.26 ± 1.24% for cinnarizine HCl and piracetam, respectively. The last method was a liquid chromatography analysis of both cinnarizine HCl and piracetam, depending on quantitative evaluation of chromatograms of cinnarizine HCl and piracetam at 252 and 212 nm, respectively, over the concentration range 10–200 μg/mL for cinnarizine HCl and 20–500 μg/mL for piracetam, with a mean accuracy of 100.03 ± 0.89 and 100.40 ± 0.94% for cinnarizine HCl and piracetam, respectively. The proposed procedures were checked using laboratory-prepared mixtures and successfully applied for the analysis of their pharmaceutical preparations. The validity of the proposed procedures was further assessed by applying the standard addition technique. Recoveries were quantitative, and the results obtained agreed with those obtained by other reported methods.
Gravimetric Method for the Determination of Diclofenac in Pharmaceutical Preparations
Authors: Tubino Matthieu , Souza Rafael L de
Published: February 2020

A gravimetric method for the determination of diclofenac in pharmaceutical preparations was developed. Diclofenac is precipitated from aqueous solution with copper(II) acetate in pH 5.3 (acetic acid/acetate buffer). Sample aliquots had approximately the same quantity of the drug content in tablets (50 mg) or in ampules (75 mg). The observed standard deviation was about ± 2 mg; therefore, the relative standard deviation (RSD) was approximately 4% for tablet and 3% for ampule preparations. The results were compared with those obtained with the liquid chromatography method recommended in the United States Pharmacopoeia using the statistical Student's t-test. Complete agreement was observed. It is possible to obtain more precise results using higher aliquots, for example 200 mg, in which case the RSD falls to 1%. This gravimetric method, contrary to what is expected for this kind of procedure, is relatively fast and simple to perform. The main advantage is the absolute character of the gravimetric analysis.
Multiresidue Determination of Eleven Quinolones in Milk by Liquid Chromatography with Fluorescence Detection
Authors: Yang Guixiang , Lin Baoyin , Zeng Zhenling , Chen Zhangliu , Huang Xianhui
Published: February 2020

A liquid chromatographic method with fluorescence detection was developed for simultaneous determination of norfloxacin, ofloxacin, ciprofloxacin, pefloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, and flumequine in milk. The samples were extracted with 10% trichloroacetic acid/acetonitrile (9 + 1, v/v) and cleaned by Strata-X reversed-phase solid-phase extraction cartridges. The 11 quinolones were separated on a reversed-phase C18 column (Hypersil BDS-C18) with mobile phase gradient elution and detected with fluorescence by means of a wavelength program. The recoveries for milk fortified with the 11 quinolones at 3 levels were 69–88%, with acceptable relative standard deviations of <9% (intraday) and <14% (interday). The limits of detection were 23 μg/L for enrofloxacin, and 1–9 μg/L for the other 10 quinolones.
Quantitative Determination of Paralytic Shellfish Poisoning Toxins in Shellfish Using Prechromatographic Oxidation and Liquid Chromatography with Fluorescence Detection: Collaborative Study
Authors: Lawrence James F , Niedzwiadek Barbara , Menard Cathie ,   Collaborators:, Rojas de Astudillo L , Biré R , Burdaspal P A , Ceredi A , Davis B , Dias E , Eaglesham G , Franca S , Gallacher S , Graham D , Hald B , Heinze L , Hellwig E , Jonker K M , Kapp K , Krys S , Kurz K , Lacaze J P , Gago Martinez A , McNabb P , Ménard C , Milandri A , Nsengiyumva C , Pereira P , Pineiro N , Poletti R , Riddell G , Selwood A , Stern A , Tiebach R , van den Top H , Wezenbeek P , Yen I C
Published: February 2020

A collaborative study was conducted for the determination of paralytic shellfish poisoning (PSP) toxins in shellfish. The method used liquid chromatography with fluorescence detection after prechromatographic oxidation of the toxins with hydrogen peroxide and periodate. The PSP toxins studied were saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins 2 and 3 (GTX2,3; together), gonyautoxins 1 and 4 (GTX1,4; together), decarbamoyl saxitoxin (dcSTX), B-1 (GTX5), C-1 and C-2 (C1,2; together), and C-3 and C-4 (C3,4; together). B-2 (GTX6) toxin was also included, but for qualitative identification only. Mussels, both blank and naturally contaminated, were mixed and homogenized to provide a variety of PSP toxin mixtures and concentration levels. The same procedure was followed with clams, oysters, and scallops. Twenty-one test samples in total were sent to 21 collaborators who agreed to participate in the study. Results were obtained from 18 laboratories representing 14 different countries. It is recommended that the method be adopted First Action by AOAC INTERNATIONAL.
Determination of Florfenicol in Fish Feed by Liquid Chromatography
Authors: Hayes John M
Published: February 2020

A simple, accurate, and reproducible assay was developed for the determination of Florfenicol in medicated fish feed. Florfenicol was extracted from ground feed into an acetonitrile–water mixture by shaking and sonication. A portion of the centrifuged extract was passed through an Envi-Carb™ solid-phase extraction cartridge, through which Florfenicol eluted unretained. The collected eluant was diluted to adjust for analyte concentration, and injected into a reversed-phase liquid chromatography system. Samples were quantitated by external standard analysis versus multilevel calibration solutions. The procedure is suitable for the quantitation of samples medicated with 0.2–4 g/kg Florfenicol. Accuracy was evaluated by 2 analysts, who determined recovery of Florfenicol from feeds fortified over a range of 0.1–6.0 g/kg. The average recovery was 100.5% (relative standard deviation, 1.2%). The linearity, accuracy, precision, reproducibility (interday and analyst), and selectivity of the method are presented. The detection and quantitation limits were determined to be 0.2 and 1.0 mg/kg, respectively.