bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Attapulgite and Nifuroxazide in Pharmaceutical Formulations by Sequential Digital Derivative Spectrophotometry
Authors: Toral M Inés , Paine Maximiliano , Leyton Patricio , Richter Pablo
Published: February 2020

A new method for the sequential determination of attapulgite and nifuroxazide in pharmaceutical formulations by first-and second-derivative spectrophotometry, respectively, has been developed. In order to obtain the optimal conditions for nifuroxazide stability, studies of solvent, light, and temperature effects were performed. The results show that a previous hydrolysis of 2 h in 1.0 × 10–1M NaOH solution is necessary in order to obtain stable compounds for analytical purposes. Subsequently, the first-and second-derivative spectra were evaluated directly in the same samples. The sequential determination of the drugs can be performed using the zero-crossing method; the attapulgite determination was carried out using the first derivative at 278.0 nm and the nifuroxazide determination, using the second derivative at 282.0 nm. The determination ranges were 5.7 × 10–6–1.0 × 10–4 and 3.7 × 10–8 –1.2 × 10–4M for attapulgite and nifuroxazide, respectively. Repeatability (relative standard deviation) values of 1.2 and 3.0% were observed for attapulgite and nifuroxazide, respectively. The ingredients commonly found in commercial pharmaceutical formulations do not interfere. The proposed method was applied to the determination of these drugs in tablets. Further, infrared spectroscopy and cyclic voltammetry studies were carried out in order to obtain knowledge of the decomposition products of nifuroxazide.
Food Allergen Detection Methods: A Coordinated Approach
Authors: Goodwin Philip R
Published: February 2020

The levels (1–2%) and increasing severity of allergic responses to food in the adult population are well documented, as is the phenomenon of even higher (3–8%) and apparently increasing incidence in children, albeit that susceptibility decreases with age. Problematic foods include peanut, milk, eggs, tree nuts, and sesame, but the list is growing as awareness continues to rise. The amounts of such foods that can cause allergic reactions is difficult to gauge; however, the general consensus is that ingestion of low parts per million is sufficient to cause severe reactions in badly affected individuals. Symptoms can rapidly—within minutes—progress from minor discomfort to severe, even life-threatening anaphylactic shock in those worst affected. Given the combination of high incidence of atopy, potential severity of response, and apparently widespread instances of “hidden” allergens in the food supply, it is not surprising that this issue is increasingly subject to legislative and regulatory scrutiny. In order to assist in the control of allergen levels in foods to acceptable levels, analysts require a combination of test methods, each designed to produce accurate, timely, and cost-effective analytical information. Such information contributes significantly to Hazard Analysis Critical Control Point programs to determine food manufacturers’ risk and improves the accuracy of monitoring and surveillance by food industry, commercial, and enforcement laboratories. Analysis thereby facilitates improvements in compliance with labeling laws with concomitant reductions in risks to atopic consumers. This article describes a combination of analytical approaches to fulfill the various needs of these 3 analytical communities.
Bioinformatics and Food Allergens
Authors: Gendel Steven M
Published: February 2020

Bioinformatics can play an important role in developing improved technology for the detection and characterization of food allergens. However, the full realization of this potential will depend on the development of allergen-specific databases as well as improved methods for data mining within these databases. Examples of existing allergen databases and analysis tools are described, as are the most important issues that need to be addressed in the next stage of database development.
Analytical Methods Used in the United Kingdom Wildlife Incident Investigation Scheme for the Detection of Animal Poisoning by Pesticides
Authors: Brown Peter M , Turnbull Gordon , Charman Sheonaidh , Charlton Andrew J A , Jones Ainsley
Published: February 2020

The United Kingdom Wildlife Incident Investigation Scheme (WIIS) investigates cases of suspected poisoning of wildlife, honey bees, and companion animals by pesticides. Together with field inquiries and veterinary post-mortem examinations, the analytical procedures presented here provide a comprehensive approach to the investigation of these cases. The paper covers selection of animal tissues for analysis and methods suitable for the analysis of honey bees and for various types of bait. Seven multiresidue methods cover around 130 pesticides, and methods are also described for a further 8 compounds. These methods are currently used on samples submitted to the Scheme in England and Wales.
Densitometric High Performance Thin-Layer Chromatography Identification and Quantitative Analysis of Psychotropic Drugs
Authors: Maślanka Anna , Krzek Jan
Published: February 2020

A thin-layer chromatography (TLC)-densitometry method has been developed to identify and quantify haloperidol, amitriptyline, sulpiride, promazine, fluphenazine, doxepin, diazepam, trifluoperazine, clonazepam, and chlorpromazine in selected psychotropic drugs. Separation was performed on precoated silica gel 60 F254 TLC plates. Chromatograms were developed in various mobile phases, and 8 of 30 tested phases were selected based on spot location and developing time. The identification and quantification were carried out based on ultraviolet densitometric measurements at chosen wavelengths. In addition to retention coefficients, the absorption spectra recorded directly from chromatograms were also used in qualitative analysis. Under established experimental conditions, high sensitivity of the method was achieved. The limit of detection ranged from 0.009 to 0.260 μg, depending on the wavelength selected for measuring. A satisfactory recovery, ranging from 92.99 to 104.70%, was achieved for individual constituents.
Determination of Metal Concentration in Fat Supplements for Swine Nutrition by Atomic Absorption Spectroscopy
Authors: Cocchi Marina , Faeti Valerio , Manfredini Matteo , Manzini Daniela , Marchetti Andrea , Sighinolfi Simona
Published: February 2020

The presence of some essential and toxic metals in fat supplements for swine diet was investigated. Collected samples represented a relevant production of the Italian industry. In particular, some samples were enriched with antioxidants or waste cooking oils. The method for the determination of Ca, Cu, Cd, Fe, Mg, Mn, Ni, Pb, and Zn in fat samples was developed by means of a certified reference material (CRM 186) and a representative fatty sample (RFS). All samples were digested in closed vessels in a microwave oven and then analyzed by flame atomic absorption or graphite furnace atomic absorption spectrometry. The entire analytical method provided a satisfactory repeatability and reproducibility confirmed by agreement between the experimental recovery data obtained for the CRM 186 sample and, with the method of standard additions, for the RFS material. The samples generally showed a small amount of metals compared with the recommended daily intake for the essential elements. On the other hand, some samples contained a significant concentration, from an analytical point of view, of Cd, Ni, and Pb. Principal component analysis (PCA) was applied to inspect the experimental data obtained from samples analysis. Basically no differences were detected in terms of metal concentration among the fat supplements analyzed.
Simultaneous Determination of Three Opiates in Serum by Micellar Liquid Chromatography Using Direct Injection
Authors: Capella-Peiró Maria-Elisa , Bose Devasish , Durgbanshi Abhilasha , Martinavarro-Domínguez Adriá , Gil-Agustí Mayte , Esteve-Romero Josep , Carda-Broch Samuel
Published: February 2020

A simple and reliable micellar liquid chromatographic method was developed for the simultaneous determination of 3 opiates (codeine, morphine, and thebaine) in serum, using direct injection and ultraviolet detection. The separation of the drugs was optimized on a C18 column, thermostatically controlled at 25°C, by evaluating mobile phases containing sodium dodecyl sulfate (SDS) and various modifiers (propanol, butanol, or pentanol). Adequate resolution of the opiates was obtained with a chemometrics approach, in which retention was modeled as a first step by using the retention factors for several mobile phases. Next, an optimization criterion that takes into account the position and shape of the chromatographic peaks was applied. The 3 opiates were totally resolved and determined in 12 min with the mobile phase 0.15M SDS–7% (v/v) butanol buffered at pH 7. The limits of detection for codeine and morphine were greatly improved by using fluorimetric detection. Repeatability and intermediate precision were tested for 3 different concentrations of the drugs, and the relative standard deviations were <0.8% for most of the assays. Finally, the method was successfully applied to the determination of morphine and codeine in serum samples.
Calf Antibiotic and Sulfonamide Test (CAST) for Screening Antibiotic and Sulfonamide Residues in Calf Carcasses
Authors: Dey Bhabani P , Reamer Richard P , Thaker Nitin H , Thaler Alice M
Published: February 2020

The Calf Antibiotic and Sulfonamide Test (CAST), a microbial inhibition screening test, was developed for detecting antibiotics and sulfonamides in bob veal calf carcasses. The test uses Bacillus megaterium ATCC 9885 as the indicator organism and Mueller Hinton agar as the growth medium. Compared to Swab Test on Premises (STOP), developed in 1970, this screening test has higher sensitivity and the ability to detect a wider range of veterinary antimicrobial residual drugs, particularly sulfonamides, at lower concentrations. Carcasses that are tested with CAST and suspected of containing chemical residue above tolerance level are retained for confirmation. Disposition of these carcasses are determined upon laboratory result. Routine testing of bob veal calves with CAST allowed the Food Safety and Inspection Service to release most calf carcasses within 24 h post-slaughter, thus conserving shipping and handling resources. However, changes in the regulation in 1990 dictate that disposition of carcasses found to contain violative levels of sulfonamide residues should be based on laboratory findings. The analysis of the data for the years 1990–1994 and 1998 indicate that the use of CAST over the years was significant, and had a direct impact on reduction of residue violations in veal carcasses. With the use of CAST, potentially harmful antimicrobial chemicals entering the human food chain through veal meat have been minimized.
Comparison Study of Two Procedures for the Determination of Emamectin Benzoate in Medicated Fish Feed
Authors: Farer Leslie J , Hayes John M
Published: February 2020

A new method has been developed for the determination of emamectin benzoate in fish feed. The method uses a wet extraction, cleanup by solid-phase extraction, and quantitation and separation by liquid chromatography (LC). In this paper, we compare the performance of this method with that of a previously reported LC assay for the determination of emamectin benzoate in fish feed. Although similar to the previous method, the new procedure uses a different sample pretreatment, wet extraction, and quantitation method. The performance of the new method was compared with that of the previously reported method by analyses of 22 medicated feed samples from various commercial sources. A comparison of the results presented here reveals slightly lower assay values obtained with the new method. Although a paired sample t-test indicates the difference in results is significant, this difference is within the method precision of either procedure.
Study of the Liquid Chromatography Retention of Some Fibrate-Type Antihyperlipidemic Drugs on C18 and CN Columns: Application for Quantitation in Pharmaceutical Formulations
Authors: Misztal Genowefa , Komsta Łukasz
Published: February 2020

The 6 antihyperlipidemic agents—bezafibrate, ciprofibrate, clofibrate, clofibric acid, fenofibrate, and gemfibrozil—were separated on octadecyl (C18) and cyano (CN) chemically bonded columns using mobile phases containing phosphate buffer and different amounts of acetonitrile, dioxane, propan-2-ol, methanol, and tetrahydrofuran. Relationships between log k values and mobile phase composition have been examined for these systems. Analysis was performed on a Waters LC system with Merck LichroCART C18 and CN 125 mm columns using a flow rate of 1 mL/min and 227 nm detection. More than one-half of the results fitted Snyder-Soczewinski equations with r > 0.995. Separation of all drugs was achieved on the C18 column with a mobile phase containing 45% propan-2-ol in phosphate buffer (pH = 2.145) and on a CN column with 20% acetonitrile in the same buffer. The best mobile phase, containing 45% propan-2-ol, was used to quantitate bezafibrate, ciprofibrate, fenofibrate, and gemfibrozil in pharmaceutical formulations. The active substances were extracted with methanol. The calibration curve was constructed in the 0.1–0.8 mg/mL range for all drugs and provided satisfactory linearity (Lack-of-Fit test and Mandel's test). The recovery function was sufficiently linear in all cases, with an insignificant intercept and slope very close to 1. Accuracy was tested by quantitating 3 fortified samples (50, 100, and 150%), which gave results without significant differences. None of the excipients interfered in the analysis. The recovery was 99.85% for bezafibrate, 99.02% for ciprofibrate, 99.53% for fenofibrate, and 99.92% for gemfibrozil, with relative standard deviation values of 0.63, 1.61, 1.84, and 0.88%, respectively.
Comparison of Various Dilutions and Solid-Phase Extraction Cleanup on the Determination of Ephedrine-Type Alkaloids and Internal Standard Recovery in Ephedra Botanical Raw Material and Powdered Extract
Authors: Trujillo William A , Sorenson Wendy R , Laluzerne Paul S , Scheuerell Chad R
Published: February 2020

A study was conducted to determine the effect of 3 dilution levels on the precision of the ephedra alkaloid method when used in conjunction with a solid-phase extraction (SPE) column. For the dilutions studied, SPE column cleanup is necessary because it promotes a greater recovery of the internal standard. However, overall, target precision values were not obtained on the test materials. It was determined that the SPE column is not the cause of the lower recovery in the more concentrated solutions. Significant signal suppression of the internal standard occurs in more concentrated solutions within the mass spectrometer. It is hypothesized that this lack of performance on the part of the SPE column may be linked to its inability to fully clean contaminants from the higher concentration solutions and/or a mass spectrometer overload, which resulted in the internal standard not fully correcting for signal suppression in more concentrated solutions. An internal standard is necessary, especially for accuracy, for the determination of all alkaloids, and only dilute solutions can be accurately analyzed. Due to the sensitivity of the mass spectrometer, it is recommended that the determination of ephedrine alkaloids in dietary supplements and botanicals should be studied using a standard graph at a level 10× less than the current method. It is also recommended that the SPE column used should be evaluated on its need for the sample dilutions made to fit the newly recommended standard graph.
Simultaneous Determination of Some Active Ingredients in Cough and Cold Preparations by Gas Chromatography, and Method Validation
Authors: Harsono Thresiana , Yuwono Mochammad , Indrayanto Gunawan
Published: February 2020

A simple and rapid gas chromatographic (GC) method has been developed for the simultaneous determination of combinations of acetaminophen, phenylpropanolamine hydrochloride, guaifenesin, pseudoephedrine hydrochloride, caffeine, chlorpheniramine maleate, and dextromethorphan hydrobromide in cough and cold tablets and syrups. After extraction of the analyte with alkaline ethyl acetate, 2 μL extract was injected (splitting ratio of 50:1) into a gas chromatograph equipped with a CBP1-M25-025 fused silica capillary column (25 m × 0.22 mm; film thickness, 0.25 μm). The column temperature was held at 150°C for 5 min, increased to 175°C at 3°C/min, and increased to 270°C at 10°C/min. The temperatures of the flame ionization detector and injector were maintained at 300°C. The GC method is inexpensive, rapid, accurate, and precise, and thus it can be used for routine analysis of tablet and syrup preparations in quality control laboratories of pharmaceutical companies.
Determination of 11 Aminoglycosides in Meat and Liver by Liquid Chromatography with Tandem Mass Spectrometry
Authors: Kaufmann Anton , Maden Kathryn
Published: February 2020

A method using liquid chromatography with tandem mass spectrometry was developed for the determination of 11 commonly used aminoglycoside antibiotics in meat. The proposed method is sufficiently sensitive (detection limits of 15 to 40 ppb for the various antibiotics) and highly selective. It is suitable for the quantitation and confirmation of aminoglycosides in a variety of matrixes (pork muscle, fish, and veal liver). Any multiresidue method for aminoglycosides must take into account their high affinity toward sample proteins and the significantly different pK values of the various analytes. The developed method uses a low-pH extraction with trichloracetic acid to ensure complete extraction of the analytes from the matrix. An anion-exchange step is used to remove the acid from the centrifuged extract. Aminoglycosides in this solution of low ionic strength can be quantitatively retained and afterwards eluted from a weak cation-exchanger solid-phase extraction (SPE) cartridge. The highly selective SPE steps produce clean extracts, which minimize possible suppression of the mass spectrometer signal.
Determination of Rosuvastatin in the Presence of Its Degradation Products by a Stability-Indicating LC Method
Authors: Mehta Tushar N , Patel Atul K , Kulkarni Gopal M , Suubbaiah Gunta
Published: February 2020

A forced degradation study was successfully applied for the development of a stability-indicating assay method for determination of rosuvastatin Ca in the presence of its degradation products. The method was developed and optimized by analyzing the forcefully degraded samples. Degradation of the drug was done at various pH values. Moreover, the drug was degraded under oxidative, photolytic, and thermal stress conditions. Mass balance between assay values of degraded samples and generated impurities was found to be satisfactory. The proposed method was able to resolve all of the possible degradation products formed during the stress study. The developed method was successfully applied for an accelerated stability study of the tablet formulation. The major impurities generated during the accelerated stability study of the tablet formulation were matches with those of the forced degradation study. The developed method was validated for determination of rosuvastatin Ca, and the method was found to be equally applicable to study the impurities formed during routine and forced degradation of rosuvastatin Ca.
Simultaneous Determination of N-Butylscopolamine and Oxazepam in Pharmaceutical Formulations by First-Order Digital Derivative Spectrophotometry
Authors: Toral Maria Inés , Muñoz Marcelo A , Orellana Sandra L
Published: February 2020

A simple method has been developed for the simultaneous determination of N-butylscopolamine bromide and oxazepam in pharmaceutical formulations using first-order digital derivative spectrophotometry. Acetonitrile was selected as the solvent in which both compounds showed well-defined bands. Both analytes showed good stability in this solvent when solutions of the analytes were exposed to light and temperatures between 20° and 80°C. The simultaneous determination of both drugs was performed by the zero-crossing method at 226.0 and 257.0 nm for N-butylscopolamine and oxazepam, respectively. The linear range of determination was found to be 2.5 × 10−7 to 8.0 × 10−5 mol/L for N-butylscopolamine and 7.1 × 10−8 to 8.0 × 10−5 mol/L for oxazepam. A very good level of repeatability (relative standard deviation) of 0.2% was observed for N-butylscopolamine and oxazepam. The ingredients commonly found in pharmaceutical formulations do not interfere. The proposed method was applied to the determination of these drugs in pharmaceutical formulations (capsules).
Comparative Validation Study to Demonstrate the Equivalence of a Minor Modification to AOAC Methods 996.09, VIP® for EHEC and 996.10, Assurance EIA® EHEC with the Reference Culture Method for the Detection of Escherichia coli O157:H7 in Beef
Authors: Feldsine Philip T , Green Shannon T , Lienau Andrew H , Kerr David E
Published: February 2020

The Visual Immunoprecipitate Assay (VIP®) method for the detection of enterohemorrhagic Escherichia coli O157:H7 (VIP for EHEC) and Assurance® Enzyme Immunoassay (EIA) method for the detection of EHEC (EHEC EIA) are AOAC INTERNATIONAL Official Methods 996.09 and 996.10, respectively. A minor modification to the enrichment medium used in both methods has been developed. This modification, the BioControl modified EHEC medium™ (BioControl mEHEC™) provides a more cost-effective procedure with performance equivalent to that of the cultural method for detection of E. coli O157:H7 in beef.
Determination of Sodium in Foods by Flame Atomic Absorption Spectrometry after Microwave Digestion: NMKL Interlaboratory Study
Authors: Julshamn Kaare , Lea Per , Norli Hilde Skaar ,   Collaborators:, Floren S , Furnes T , Grønningen D , Haugsnes J , Jensen A , Jensen A H , Jiang L , Karjalainen S , Kildahl B T , Kivikari R , Lathi J , Løvhøyden F , Palmadottir H , Rasmussen L , Riebe M , Sloth J J , Wang-Andersen J
Published: February 2020

Nine laboratories participated in an interlaboratory method performance (collaborative) study of a method for the determination of sodium in foods by flame atomic absorption spectrometry after wet digestion, using a microwave oven technique. Before the study, the laboratories were able to practice on samples with defined sodium levels (pretrial test). The method was tested on a total of 6 foods (broccoli, carrot, bread, saithe fillet, pork, and cheese) with sodium concentrations of 1480–8260 mg/kg. The materials were presented to the participants in the study as blind duplicates, and the participants were asked to perform single determinations for each sample. The repeatability relative standard deviations (RSDr) for sodium ranged from 1.9 to 6.5%. The reproducibility relative standard deviations (RSDR) ranged from 4.2 to 6.9%. The HorRat values ranged from 0.9 to 1.6.
Quantitative Determination of Saccharides in Dietary Glyconutritional Products by Anion-Exchange Liquid Chromatography with Integrated Pulsed Amperometric Detection
Authors: Eberendu Alexis R , Booth Christy , Luta Gabriela , Edwards Joshua A , McAnalley Bill H
Published: February 2020

A new technique for the assay of carbohydrates is described in which separation and quantification of neutral saccharides, aminosaccharides, glycuronic acids, and disaccharides may be accomplished in less than 50 min of total run time. This method involves optimized anion-exchange liquid chromatography coupled with integrated pulse amperometric detection. Complex carbohydrates from various sources, including dietary supplements, were hydrolyzed in a dilute solution of trifluoroacetic acid, freeze-dried, and reconstituted in water containing 2-deoxygalactose as the internal standard. The solution was filtered and separated on CarboPac PA20 column. The eluted saccharides were detected by oxidation on a gold electrode with quadruple-pulsed integrated amperometry. The calibration plots for the saccharides were linear with an average correlation coefficient of 0.999. Method precisionc regarding peak retention time and resolution used in the peak identifications was verified. With this method, previously difficult-to-separate saccharides, such as galactosamine, glucosamine, and N-acetylglucosamine, were successfully resolved from the neutral saccharides rhamnose, arabinose, and galactose. Mannose was also resolved from xylose, and de-acetylation of aminosaccharides prior to separation was not necessary. This technique provides an accurate and efficient means to assay carbohydrates in dietary supplements, which new federal regulations will soon mandate.
Determination of Total Monomeric Anthocyanin Pigment Content of Fruit Juices, Beverages, Natural Colorants, and Wines by the pH Differential Method: Collaborative Study
Authors: Lee Jungmin , Durst Robert W , Wrolstad Ronald E ,   Collaborators:, Eisele T , Giusti M M , Hach� J , Hofsommer H , Koswig S , Krueger D A , Kupina; S , Martin S K , Martinsen B K , Miller T C , Paquette F , Ryabkova A , Skrede G , Trenn U , Wightman J D
Published: February 2020

This collaborative study was conducted to determine the total monomeric anthocyanin concentration by the pH differential method, which is a rapid and simple spectrophotometric method based on the anthocyanin structural transformation that occurs with a change in pH (colored at pH 1.0 and colorless at pH 4.5). Eleven collaborators representing commercial laboratories, academic institutions, and government laboratories participated. Seven Youden pair materials representing fruit juices, beverages, natural colorants, and wines were tested. The repeatability relative standard deviation (RSDr) varied from 1.06 to 4.16%. The reproducibility relative standard deviation (RSDR) ranged from 2.69 to 10.12%. The HorRat values were ≤1.33 for all materials. The Study Director recommends that the method be adopted Official First Action.
Evaluation of the Assurance GDS™ for E. coli O157:H7 Method and Assurance GDS for Shigatoxin Genes Method in Selected Foods: Collaborative Study
Authors: Feldsine Philip T , Green Shannon T , Lienau Andrew H , Stephens James , Jucker Markus T , Kerr David E ,   Collaborators:, Bark D , Belousov Y S , Benish B , Brillhart D E , Camacho A , Deans A , Douangmala A , Forgey; R , Grant M , Gringer G , Hunsucker J C , Hyunh P , Johnson K , Lockhart L D , Luebbert B , Metcalf M , Moser R , Norris C , Oostra K , Pickett J L , Potter L , Roa N , Solano S , Tuncan E , Vrana D , Wilson J
Published: February 2020

A multilaboratory collaborative study was conducted to compare the Assurance GDS™ for E. coli O157:H7 method and the reference culture methods for the detection of E. coli O157:H7 in orange juice, raw ground beef, and fresh lettuce. A separate companion assay, the Assurance GDS for Shigatoxin Genes method was also evaluated with the same test portions. Fifteen laboratories participated in the study. A Chi square analysis of each of the 3 food types at the high, low, and uninoculated control levels was performed. For all foods, the Assurance GDS for E. coli O157:H7 method and the Assurance GDS for Shigatoxin Genes method were equivalent to or better than the reference methods.
Determination of 1,3-Dichloropropanol in Soy Sauce and Related Products by Headspace Gas Chromatography with Mass Spectrometric Detection: Interlaboratory Study
Authors: Hasnip Sarah , Crews Colin , Potter Nicholas , Brereton Paul , Diserens Henri , Oberson Jean-Marie ,   Collaborators:, Baigrie B , Byrd N , Campbell D J , Diserens H , Hageman L , Hollywood F , Noro Y , Nyman P , Wehage H
Published: February 2020

An interlaboratory study was performed to evaluate the effectiveness of a headspace gas chromatography (GC) method for the determination of 1,3-dichloro-propan-2-ol (1,3-DCP) in soy sauce and related products at levels above 5 ng/g. The test portion is mixed with an internal standard (d5-1,3-DCP) and ammonium sulfate in a sealed headspace vial. After achieving equilibrium, the headspace is sampled either by gas-tight syringe or solid-phase microextraction (SPME) and analyzed by GC with mass spectrometric detection. 1,3-DCP is detected in the selected-ion mode (monitoring m/z 79 and 81 for 1,3-DCP and m/z 82 for the deuterated internal standard) and quantified by measurement against standards. Test materials comprising soy, dark soy, mushroom soy, and teriyaki sauces, both spiked and naturally contaminated, were sent to 9 laboratories in Europe, Japan, and the United States; of these, 5 used SPME and 4 used syringe headspace analysis. Test portions were spiked at 5.0, 10.0, 20.0, 100.0, and 500.0 ng/g. The average recovery for spiked blank samples was 108% (ranging from 96–130%). Based on results for spiked samples (blind pairs at 5, 10, 20, 100, and 500 ng/g) as well as a naturally contaminated sample (split-level pair at 27 and 29 ng/g), the relative standard deviation for repeatability (RSDr) ranged from 2.9–23.2%. The relative standard deviation for reproducibility (RSDR) ranged from 20.9–35.3%, and HorRat values of between 1.0 and 1.6 were obtained.
Liquid Chromatographic Determination of Flumetsulam in Soybeans
Authors: Moawad Michael , Khoo Cheang S
Published: February 2020

A liquid chromatography (LC) method with UV detection is reported for the determination of the sulfonamide herbicide flumetsulam in soybeans. The ground soybean sample was partitioned between methanol and hexane. The hexane removed the lipids, and the methanol layer containing the analyte was further partitioned between dichloromethane and aqueous phosphate buffer at pH 7.0. The aqueous layer, containing the analyte, was acidified to pH 2.2 and partitioned with fresh dichloromethane. The dichloromethane layer containing the analyte was evaporated, and the residue was dissolved in the LC mobile phase for analysis. A polar embedded C18 column was used with a mobile phase of pH 2.2 aqueous phosphate buffer–acetonitrile (68 + 32), run isocratically with detection at 225 nm. The average recovery was 82% with a relative standard deviation (RSD) of 10%. A coefficient of determination of R2 = 0.9992 was achieved for the analyte calibration curve, from 0.005 to 1 μg/mL. The limit of detection, determined from 3 times the standard deviation of 7 replicate extractions of the lowest fortification level (0.01 μg/g, was 0.005 μg/g with an RSD of 22%. LC/electrospray ionization/mass spectrometry in the positive-ion mode was used for identity confirmation of flumetsulam in the fortified soybean extract. The ions at m/z 326, 348, and 129 were observed.
Determination of 22 Triazole Compounds Including Parent Fungicides and Metabolites in Apples, Peaches, Flour, and Water by Liquid Chromatography/TandemMass Spectrometry
Authors: Schermerhorn Patricia G , Golden Paul E , Krynitsky Alexander J , Leimkuehler William M
Published: February 2020

A liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed for the determination of 14 parent triazole fungicides and 8 of their metabolites found in apples, peaches, flour, raw water, and tap water. The triazole fungicides chosen for this multiresidue method development project included propiconazole, fenbuconazole and its RH-9129 and RH-9130 metabolites, cyproconazole, difenoconazole, tebuconazole and its HWG 2061 metabolite, hexaconazole, bromuconazole (both stereoisomers), epoxiconazole, tetraconazole, triticonazole and its RPA-404886 and RPA-406341 metabolites, triadimefon, triadimenol, and myclobutanil. Of special concern to the U.S. Environmental Protection Agency were the metabolites common to all triazole fungicides: free triazole, 1,2,4-triazole (T), and its 2 conjugates: triazolylalanine (TA) and triazolylacetic acid (TAA). These metabolites were the primary focus of this project. All samples we cleaned up by a combination of C18 solid-phase extraction (SPE), mixed-mode cationic SPE, and mixed-mode anionic SPE columns. A triple-stage quadrupole mass spectrometer, equipped with electrospray ionization in the positive-ion mode, was used to determine the compounds of interest. T, TA, and TAA were quantitated using isotopically labeled internal standards (IS), in which the 1,2,4-triazole ring had been synthesized by using 13C and 15N (IS_T, IS_TA, and IS_TAA). These isotopically labeled internal standards were necessary to correct for matrix effects. The T, TA, and TAA metabolites were quantitated at the 25–50 parts-per-billion (ppb) level in food commodities and at 0.50 ppb in water. Recoveries were 70–101% from apples, 60–121% from peaches, 57–118% from flour, 75–99% from raw water, and 79–99% from tap water.
Sample Sizes Needed for Specified Margins of Relative Error in the Estimates of the Repeatability and Reproducibility Standard Deviations
Authors: McClure Foster D , Lee Jung K
Published: February 2020

Sample size formulas are developed to estimate the repeatability and reproducibility standard deviations (sr and sR) such that the actual error in (sr and sR) relative to their respective true values, σr and σR, are at predefined levels. The statistical consequences associated with AOAC INTERNATIONAL required sample size to validate an analytical method are discussed. In addition, formulas to estimate the uncertainties of (sr and sR) were derived and are provided as supporting documentation.Formula for the Number of Replicates Required for a Specified Margin of Relative Error in the Estimate of the Repeatability Standard Deviation
Simultaneous High-Performance Thin-Layer Chromatography Densitometric Assay of Trandolapril and Verapamil in the Combination Preparation
Authors: Kowalczuk Dorota
Published: February 2020

A high-performance thin-layer chromatography (TLC) method coupled with densitometric analysis has been developed for simultaneous measurement of trandolapril (TRA) and verapamil (VER) in 2-component mixtures and in their combination capsules. The active substances were extracted from capsules withmethanol (mean recovery: 103.4% for TRA, 97.13% for VER) and chromatographed on TLC plates coated with silica gel 60 F254 in horizontal chambers with ethyl acetate–ethanol–acetic acid (8 + 2 + 0.5, v/v) mobile phase. Chromatographic separation of these components was followed by ultraviolet densitometric quantification at 215 nm. The calibration graphs were constructed over the concentration range from 0.5 to 1.5 μg/μL (corresponding to 5.0–15.0 μg/spot for both drugswith good correlation (r ≥ 990). Detection and quantitation limits were found to be 1.25 and 3.75 μg/spot for TRA and 0.15 and 0.45 μg/spot for VER, respectively. The proposed method was used for determination of both drugs in TRA-VER capsules with satisfactory precision [0.97% < relative standard deviation (RSD) <4.50% for TRA, 0.49% < RSD < 3.10% for VER] and accuracy [2.16% < relative error (RE) < 4.90% for TRA, 1.73% < RE < 5.68% for VER].
Comparison of the Compact Dry TC Method with the Standard Pour Plate Method (AOAC Official Method 966.23) for Determining Aerobic Colony Counts in Food Samples: Performance-Tested MethodSM
Authors: Kodaka Hidemasa , Mizuochi Shingo , Teramura Hajime , Nirazuka Tadanobu
Published: February 2020

Compact Dry TC qualifies as a rapid method kit for determining aerobic colony counts in foods. The plates are presterilized and contain culture medium and a cold-soluble gelling agent. The medium is rehydrated by inoculating 1 mL diluted sample into the center of the self-diffusible medium and allowing the solution to diffuse by capillary action. The plates can then be incubated and the colonies counted without any additional steps. The Compact Dry TC method was validated with 5 different raw meats. The performance tests were conducted at 35° and 30°C. In all required performance studies, no apparent differences were observed between the Compact Dry TC method and the Standard Pour Plate method (AOAC Official Method 966.23) for the detection level of aerobic microorganisms. For the accuracy claim (n = 60), a correlation factor of r235 = 0.9977 (35°C) and r230 = 0.9932 (30°C) could be assigned, as stated in the application for “Performance Tested Method.SM” Quality consistency and storage robustness studies, showed no significant variations in plate count results with different production lots or plates of diverse storage age.
Determination of Mercury in Carbon Black by Cold Vapor Atomic Absorption Spectrometry
Authors: Hepp Nancy M
Published: February 2020

Recently, a new color additive, D&C Black No. 2, a high-purity furnace black in the general category of carbon blacks, was listed as a color subject to batch certification by the U.S. Food and Drug Administration. Asimple procedure was developed to determine mercury (Hg) in D&C Black No. 2, which is limited by specification to not more than 1 ppm Hg. The method uses partial acid digestion followed by cold vapor atomic absorption and was developed bymodifying a method used for other color additives. The carbon black samples are treated with amixture of nitric and hydrochloric acids and heated by microwave in sealed Teflon vessels. The resulting solutions, which are stable to Hg loss for at least 1 week, are diluted and analyzed for Hg using cold vapor atomic absorption spectrometry. Validation was performed by spiking carbon black samples with inorganic Hg (HgNO3) at levels from 0.1 to 1.5 /g, and by analyzing 2 standard reference materials. At the specification level of 1 ppm Hg (1 g Hg/g), the 95% confidence interval was 0.01 ppm Hg (0.01 g Hg/g). The method developed in this study gave good results for very difficult-to-analyze materials, such as coal standard reference materials and carbon black. By eliminating volatility and adsorption factors through the formation of HgCl42 complexes, one can avoid using extremely hazardous acids such as HF and HClO4.
Liquid Chromatographic Determination of N-Methyl Carbamate Pesticide Residues at Low Parts-Per-Billion Levels in Eggs
Authors: Schenck Frank J , Podhorniak Lynda V , Hobbs James , Casanova John , Donoghue Dan
Published: February 2020

A reversed-phase liquid chromatographic (LC) method is presented for the analysis of N-methyl carbamate pesticide residues and piperonyl butoxide in eggs at levels as low as 2 gkg (ppb). The study was undertaken to provide data for dietary exposure estimates used in risk analysis. The method uses an acetonitrile extraction followed by liquidliquid partitioning and normal-phase aminopropyl solid-phase extraction column cleanup. Determination of residues is by reversed-phase LC with an inline postcolumn reaction followed by fluorescence detection. The average recoveries of 21 fortified (most at 2.0 and 20.0 ppb) N-methyl carbamate pesticide residues and the carbamate metabolite 1-naphthol from eggs ranged from 70 to 107%. Recoveries of the pesticide synergist piperonyl butoxide ranged from 63 to 106%. Single-comb White Leghorn hens were treated with the carbamate carbaryl, and the eggs subsequently produced were analyzed for carbaryl and 1-naphthol residues.
Determination of Coenzyme Q10 in Over-the-Counter Dietary Supplements by High-Performance Liquid Chromatography with Coulometric Detection
Authors: Tang Peter H
Published: February 2020

A rapid and sensitive method is described for the determination of coenzyme Q10 (Q10) in over-the-counter dietary supplements by automated high-performance liquid chromatography (HPLC) with coulometric detection. Sample solutions of powder-filled capsules, oil-based softgels, and tablets were prepared by serial dilution with 1-propanol. After dilution, a known volume of sample solution containing Q10 and the internal standard, coenzyme Q9 (Q9), was directly injected into the HPLC system. Most of electrochemically active compounds in the injection were oxidized at the precolumn conditioning cell and postcolumn guard cell. Q9 and Q10 were monitored at an analytical cell that contained 2 coulometric electrodes, where Q9 and Q10 were reduced to the corresponding ubiquinol-9 and -10 and then oxidized to produce currents. This method produced a linear detector response for peak height measurements over the concentration range of 0.058 g/mL (r > 0.999). The lower limit of detection was 5 ng/mL (signal-to-noise ratio, 3). The mean recovery was 98.9 0.6%; coefficients of variation for intra- and interday precisions were 1.84.0%. The proposed method was successfully applied to the determination of Q10 in marketed products.
A Simple and Rapid High-Performance Liquid Chromatography Method for Determining Furosemide, Hydrochlorothiazide, and Phenol Red: Applicability to Intestinal Permeability Studies
Authors: Valizadeh Hadi , Zakeri-Milani Parvin , Islambulchilar Ziba , Tajerzadeh Hosniyeh
Published: February 2020

A simple reversed-phase high-performance liquid chromatography (HPLC) method with ultraviolet detection at 280 nm was developed for simultaneous quantitation of furosemide and hydrochlorothiazide along with phenol red as a nonabsorbable marker for in situ permeability studies in anaesthetized rats. A jejunal segment of approximately 10 cm was isolated and cannulated in both ends for inlet and outlet solution. The perfusate was collected every 10 min, and samples were analyzed using the developed method. The mobile phase was acetonitrile-watser-triethylamine-glacial acetic acid (41.5 + 57.4 + 0.1 + 0.9, adjusted to pH 5.6) at a flow rate of 1 mL/min; the run time was 9 min. The calibration graphs were linear for all 3 compounds (r > 0.999) across the concentration range of 7.93-125 μg/mL for phenol red and 6.25-100 μg/mL for hydrochlorothiazide and furosemide. The limits f quantitation were 7.2, 8.9, and 6.8 μg/mL for furosemide, hydrochlorothiazide, and phenol red, respectively. The coefficients of variation for intraassay and interassay precision were less than or equal to 7.6%, and the accuracy was between 93.2103.4%. Using the single pass intestinal perfusion technique and the suggested HPLC method for sample analysis, mean values of 0.25 10-4(±0.16) cm/s and 0.22 10-4 (±0.13) cm/s were obtained for furosemide and hydrochlorothiazide, respectively.
Application of Inorganic Oxidants to the Spectrophotometric Determination of Ribavirin in Bulk and Capsules
Authors: Darwish Ibrahim A , Khedr Alaa S , Askal Hassan F , Mohamed Ramadan M
Published: February 2020

Eight spectrophotometric methods for determination of ribavirin have been developed and validated. These methods were based on the oxidation of the drug by different inorganic oxidants: ceric ammonium sulfate, potassium permanganate, ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate. The oxidation reactions were performed in perchloric acid medium for ceric ammonium sulfate and in sulfuric acid medium for the other reagents. With ceric ammonium sulfate and potassium permanganate, the concentration of ribavirin in its samples was determined by measuring the decrease in the absorption intensity of the colored reagents at 315 and 525 nm, respectively. With the other reagents, the concentration of ribavirin was determined by measuring the intensity of the developed colored reaction products at the wavelengths of maximum absorbance: 675, 780, 595, 595, 475, and 475 nm for reactions with ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate, respectively. Different variables affecting the reaction conditions were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.99840.9998) were found between the absorbance readings and the concentrations of ribavirin in the range of 41400 g/mL. The molar absorptivities were correlated with the oxidation potential of the oxidants used. The precision of the methods were satisfactory; the values of relative standard deviation did not exceed 1.64%. The proposed methods were successfully applied to the analysis of ribavirin in pure drug material and capsules with good accuracy and precision; the recovery values were 99.2101.2 0.481.30%. The results obtained using the proposed spectrophotometric methods were comparable with those obtained with the official method stated in the United States Pharmacopeia.
Determination ofMagnesium Stearate in Capsule- or Tablet-Type Supplements
Authors: Uematsu Yoko , Ogimoto Mami , Kabashima Junichirou , Ito Kouichi , Yasuda Kazuo
Published: February 2020

A simple method for the determination of magnesium stearate in capsule- or tablet-type supplements was developed. Free stearic acid in the sample was removed by extraction with tetrahydrofuran. The remaining stearate was converted to stearic acid by reaction with a cation-exchange resin. The resulting stearic acid was determined by gas chromatography with a polar column. Esters of stearic acid were not converted to stearic acid and would not cause a positive error in the amount of stearate. The amount of magnesium stearate was calculated based on the stearic acid concentration thus obtained. Magnesium stearate levels in 5 out of 25 supplements exceeded 2500 g/g, which indicated the possible admixture of magnesium stearate.
Matrix Solid-Phase DispersionMicroextraction and Determination of Pesticide Residues in Medicinal Herbs by Gas Chromatography with a Nitrogen-Phosphorus Detector
Authors: Tang Feng , Yue Yongde , Hua Rimao , Cao Haiqun
Published: February 2020

Agas chromatography method for the determination of residues of 6 pesticides in Isatis indigotica Fort and Paeonia lactiflora Pall is described. Optimizations of different parameters were performed. The method used 0.5 g herb sample, silica gel as thematrix solid-phase dispersion sorbent, and acetone as the eluting solvent. Recoveries at spiked concentrations between 0.1 and 5mg/kg were between 80.63 and 110.12, with relative standard deviations ranging from 0.43 to 17.67. The limits of quantitation were 0.01 mg/kg for metalaxyl, triadimefon, and paclobutrazol and 0.05mg/kg for vinclozolin, tebuconazole, and fenarimol. The method may be useful as a screening protocol for the determination of these pesticides in medicinal herb samples.
Verification of a Method for Microcoulometric Determination of Adsorbable Organic Halide Pollutants in Natural, Drinking, Waste, and Treated Waters
Authors: Ivanova Pavlina , Stratiev Ditso , Pavlova Antoaneta
Published: February 2020

A microcoulometric method is described for the determination of organic-halide pollutants at 2-2000 μg/L in natural, drinking, waste, and treated waters. The conditions for the adsorption of organic halides, using a microcolumn with activated charcoal-and for the desorption of inorganic halides-as well as for the pyrolysis process, were optimized for the successful determination of priority organic halide pollutants. An appropriate criterion was proposed to stop the desorption step. The mean recovery was 100.3%, and the mean relative standard deviation was 9.9%. The detection limit based on 3 times the standard deviation of the blank sample was 2 μg/L.