bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monitoring of Domestic and Imported Apples and Rice by the U.S. Food and Drug Administration Pesticide Program
Authors: Roy Ronald R , Wilson Patrick , Laski Ronald R , Roberts James I , Weishaar Joseph A , Bong Rodney L , Yess Norma J 
Published: February 2020

Abstract
In 1993-94, the U.S. Food and Drug Administration (FDA) conducted a statistically based study of pesticide residues in domestic and imported fresh apples and processed rice. For apples, 769 domestic and 1062 imported samples were collected and analyzed; 85% of the domestic and 86% of the imported samples had detectable residues. Benomyl, a widely used fungicide, was found with greatest frequency in domestic apples, while diphenylamine was found most often in imported apples. One domestic and 4 imported samples contained violative residues of pesticides for which there are no U.S. tolerances on apples. The statistically weighted (by domestic packer throughput or import shipment size) violation rates for domestic and imported apples were 0.30% (0.13 unweighted) and 0.41% (0.38 unweighted), respectively. For rice, 598 domestic and 612 imported samples were collected and analyzed; 56% of the domestic and 12% of the imported samples had detectable residues. Malathion had the greatest frequency of occurrence in both groups of rice. Eight domestic and 9 imported samples were violative, all as a result of use of pesticides for which there are no U.S. tolerances on rice. The statistically weighted violation rates for domestic and imported rice were 0.43% (1.3 unweighted) and 1.1% (1.5 unweighted), respectively. Results of the statistically based study show that, as in FDA’s regulatory monitoring, the levels of most pesticide residues found in these 2 commodities are generally well below U.S. tolerances, and few violative residues are found.
Analyses of Chlorothalonil and Dichlofluanid in Greenhouse Air
Authors: González Fj. Egea , Cano M L Castro , Vidal J L Martínez , Galera M Martínez 
Published: February 2020

Abstract
A method to sample and analyze chlorothalonil and dichlofluanid in greenhouse air was evaluated. Analysis was performed by gas chromatography with electron capture detection and gas chromatography- mass spectrometry. Solid sorbents such as Chromosorb 102, Porapak R, Supelpak-2, AmberliteXAD-2, Amberlite XAD-4, and polyurethane foam were studied. The use of Soxhlet extraction and solvent desorption with sonication to desorb the pesticides from these sorbents were compared.A procedure to generate atmospheres containing known concentrations of these fungicides was established to study sorption capacity and samplingconditions. Breakthrough and storage of pesticides also were studied. Dissipation of analytes in a 24 h period after application was studied by using personal samplers in a field experiment.
Determination of Four Fluoroquinolones in Milk by Liquid Chromatography
Authors: Roybal José E , Pfenning Allen P , Turnipseed Sherri B , Walker Calvin C , Hurlbut Jeffrey A 
Published: February 2020

Abstract
A liquid chromatographic (LC) method with fluorescence detection is presented for the analysis of 4 fluoroquinolones; enrofloxacin (ENRO), ciprofloxacin (CIPRO), sarafloxacin (SARA), and difloxacin (DIFLX) in milk. The procedure consists of extraction of milk with acidified ethanol, isolation and retention on a cation exchange solid-phase extraction column, elution with basic methanol, and LC analysis with fluorescence detection. LC analysis is performed by isocratic elution using an acetonitrile-2% acetic acid (15 + 85) mobile phase and an Inertsil phenyl column with fluorescence detection at excitation and emission wavelengths of 278 and 450 nm, respectively. A target level of 10 ppb for each of the 4 fluoroquinolones has been established for this method. Average recovery from fortified raw milk samples (5-100 ppb each) based on a 5-point standard curve calculation was 70-90%, with relative standard deviations of &lt;15%.
Determination of Tilmicosin in Swine Feeds by Liquid Chromatography
Authors: Readnour Robin S , Helton-Groce Susan L , Dixon Sharon S 
Published: February 2020

Abstract
This method determines tilmicosin in feeds over a concentration range of 100 to 600 mg/kg. Tilmicosin is extracted from swine feeds by adding 200 mL of a swine feed extractant (20 + 80, acetonitrile–Millipore water, pH 2.5, with 25 mM dibutylammonium phosphate) to 20 g feed and placing on a shaker table for 1 h. This extractant is filtered and analyzed by liquid chromatography (LC). A gradient LC method is used to separate ilmicosin from the feed matrix in 30 min of run time. The recovery of tilmicosin from fortified feeds ranged from 96.7 to 112%, with the coefficients of variation (CVs) ranging from 1.4 to 3.9%. The determination of tilmicosin in medicated feeds resulted in an average recovery of 92.7% of labeled claim for pelleted feeds at 200 mg/kg and 99.1% of labeled claim for mash feeds at 400 mg/kg. Determination of tilmicosin in medicated feeds resulted in CVs ranging from 2.6 to 3.8%. The method has shown no interference with 18 other drugs.
Validated Method for Quantitation and Identification of 4,4-Desmethylsterols and Triterpene Diols in Plant Oils by Thin-Layer Chromatography–High Resolution Gas Chromatography–Mass Spectrometry
Authors: Reina Robert J , White Kevin D , Jahngen Edwin G E 
Published: February 2020

Abstract
Alkaline hydrolysis was performed on a series of different vegetable oils. The unsaponifiable lipid matter was extracted with ethyl ether, and the class of 4,4-desmethylsterols (sterols) plus the triterpene diols (diols) erythrodiol, uvaol, and betulinol were isolated by thin-layer chromatography. A validated method using the acetate derivatives of sterols instead of their silyl ethers is presented. The acetate derivatives were analyzed by high resolution gas chromatography (HRGC). Retention time, precision, recovery studies, and absolute response factors were calculated for these esters, and GC/mass spectrometric structure of the assigned retention times was confirmed for the sterols and triterpene diols.
Determination of Chlorinated Phenols in Water and Soil by Capillary Zone Electrophoresis
Authors: Rae Wayne E , Lucy Charles A 
Published: February 2020

Abstract
A capillary zone electrophoresis (CZE) method was developed to separate and determine chlorinated phenols in water and soil samples. A mixture of 16 chlorinated phenols was resolved in 25 min by using a 77 cm (70 cm to detector) × 75 μm fused silica capillary with 0.015M tetraborate/0.045M phosphate (pH 7.3) buffer at 22 kV. Calibration linearities for water samples in the low parts-permillion range were good (correlation coefficient &gt; 0.99) for all solutes except p-chlorophenol. Average precision was 17% relative standard deviation. Typical detection limits were in the 200 μg/L range. Recoveries of chlorinated phenols from synthetic soil samples with methanol were quantitative.
Improvements in Amperometric Detection of Sulfite in Food Matrixes
Authors: Wygant Michele B , Statler John A , Henshall Alan 
Published: February 2020

Abstract
Sulfite is added to foods as an antimicrobial, antibrowning agent, or antioxidant. It also can occur naturally, and is often used in the production of beer and wine. For years the standard methodology for determination of sulfite in foods has been the Monier–Williams method, which is a combination of acid distillation and titration. Recently, AOAC adopted a chromatographic method based on a method developed by Kim and Kim for the determination of sulfite. The method combines ion exclusion chromatography with direct-current (DC) amperometric detection to provide more convenient and accurate quantitation of sulfite. However, fouling of the platinum working electrode results in a rapid decrease in method sensitivity. As a result, standards must be injected before and after every sample, and the electrode must be polished frequently to maintain adequate detection limits. Pulsed amperometric detection overcomes electrode fouling problems by repeatedly and continuously applying cleaning potentials to the working electrode. Using this technique, a reproducible electrode surface can be maintained, and injection-to-injection repeatability is greatly improved. A comparison of method performance for both DC and pulsed amperometric detection is presented. Also investigated was the stability of sulfite samples at varying pH, and in the presence or absence of a preservative.
Liquid Chromatographic Determination of Major Secondary Metabolites Produced by Aspergillus Species from Section Flavi
Authors: Sobolev Victor S , Horn Bruce W , Dorner Joe W , Cole Richard J 
Published: February 2020

Abstract
A liquid chromatographic (LC) method was developed for simultaneous determination of major secondary metabolites—including cyclopiazonic acid (CPA), O-methylsterigmatocystin (OMST), and the versicolorins—produced by Aspergillus species from section Flavi (A. flavus, A. parasiticus, A. tamarii, and A. caelatus) on a liquid medium. Metabolites were extracted with chloroform and quantitated without prior cleanup by means of normal- phase ion-pair partition LC on silica gel with a mobile phase of n-heptane-2-propanol-n-butanolwater- tetrabutylammonium hydroxide (2560 + 900 + 230 + 32 + 8, v/v). Recoveries of CPA and OMST from fungal cultures spiked at 10 μg/mL were 98.90 + 3.27 and 95.92 + 5.27% (n = 5), respectively. At spike levels of 100 μg/mL, recoveries were 98.89 + 3.87 and 97.65 + 4.32% (n = 5), respectively. Limits of detection for pure standards were 0.25 μg/mL for CPA (at 280 nm) and 0.30 μg/mL for OMST (at 310 nm). UV detector responses to CPA and OMST were linear to about 0.5 and 3.5 μg/injection, respectively
Reversed-Phase Ion-Pair Liquid Chromatographic Determination of Chlorophacinone and Diphacinone in Steam- Rolled Oat Baits and Steam-Rolled Oat/Wax Baits
Authors: Primus Thomas M , Griffin Doreen L , Volz Stephanite A , Johnston John J 
Published: February 2020

abstract
A reversed-phase ion-pair liquid chromatographic (LC) method was developed for analysis of steam-rolled oat (SRO) baits fortified with either chlorophacinone or diphacinone. Baits were prepared with and without paraffin wax. Chlorophacinone or diphacinone was extracted from wax-free SRO baits with 5 mM tetrabutylammonium phosphate methanolic ion-pairing solution. Wax baits were initially extracted with petroleum ether and then cleaned up by liquid extraction into methanolic ion-pairing solution containing 20% water. SRO extracts were analyzed with reversed-phase ion-pair LC. Chlorophacinone and diphacinone were quantified by UV absorption at 325 nm. Recoveries from SRO fortified with chlorophacinone at 25 and 150 μg/g were 90.7 and 90.8%, respectively, whereas for diphacinone at the same levels, recoveries were 93.5 and 92.3%, respectively. Recoveries from wax baits fortified at 25 and 75 μg/g chlorophacinone were 98.5 and 100%, respectively, whereas for diphacinone at the same levels, recoveries were 93.6 and 98.0%, respectively. Method limits of detection for chlorophacinone and diphacinone in SRO baits were estimated to be 1.0 and 0.76 μg/g, respectively. Method limits of detection for chlorophacinone and diphacinone in wax baits were estimated to be 4.2 and 2.8 μg/g, respectively.
Determination of Diarrheic Shellfish Toxins in Mussels b Microliquid Chromatography-Tandem Mass Spectrometry
Authors: Draisci Rosa , Lucentini Luca , Giannetti Luigi , Boria Pierpaolo , James Kevin J , Furey Ambrose , Gillman Marion , Kelly Séan S 
Published: February 2020

abstract
A fast, sensitive, and specific procedure for determining toxins that cause diarrheic shellfish poisoning (DSP) using microliquid chromatography coupled with tandem mass spectrometry (micro-LC-MS-MS) is reported. The lipophylic polyether acidic toxins okadaic acid (OA), its isomer dinophysistoxin-2 (DTX-2), the 35-methylokadaic acid dinophysistoxin-1 (DTX-1), and the novel toxin dinophysistoxin-2B (DTX-2B; recently isolated from Irish mussels) were extracted from shellfish tissues with acetone and chromatographed by isocratic elution at 10 ixL/min with CH3CN-H20, 80 + 20 (v/v), containing 0.1% trifluoroacetic acid, through a C18 reversed-phase column (1.0 mm id). The chromatograph is coupled via an ion spray interface to an atmospheric pressure ionization source. Collision-induced-dissociation (CID) ion mass spectra of the protonated molecule, [M + H]+, at m/z 805 for OA, DTX-2, and DTX-2B and at m/z 819 for DTX-1, were obtained in MS-MS experiments to identify 2 diagnostic fragment ions for each analyte that could be used for selected-reaction-monitoring (SRM) micro-LC-MS-MS analysis. The CID spectrum of DTX-2B confirmed it to be a new OA isomer, like DTX-2. Standard curves obtained by SRM micro-LC-MS-MS were linear (r2 μ 0.9992) over the range 0.05-1.00 μg/mL (i.e., 0.10-2.00 μg toxin/g hepatopancreas), and a detection limit of 15 pg/injection was obtained for each DSP toxin. Average recoveries ranged from 95 to 101%, and coefficients of variation ranged from 1.8 to 3.4%. This novel SRM micro-LC-MS-MS method was used to confirm acidic DSP toxins in Irish and Italian toxic mussels. It offers a high degree of specificity because analyte confirmation is based on retention time, molecular weight, structural information obtained from the presence of 2 diag-nostic fragments for each analyte, and ion ratios. OA was found in both Irish (&lt; 0.7 μg/g hepatopancreas) and Italian (&lt;1.5 μg/g hepatopancreas) mussels. DTX-1 was found only in Italian mussels (&lt;0.3 μg/g hepatopancreas). DTX-2 (&lt;6.1 μg/g hepatopancreas) and DTX-2B (&lt;0.08 μg/g hepatopancreas) were unique to Irish shellfish.
Optimization of Selenium Determination in Human Milk and Whole Blood by Flow Injection Hydride Atomic Absorption Spectrometry
Authors: Alegría Amparo , Barberá Reyes , Farré Rosaura , Ferrer Emilia , Lagarda M Jesús , Torres M Angeles 
Published: February 2020

abstract
A flow injection hydride atomic absorption spectrometry (FI-HAAS) method was developed for determining selenium in human milk and whole blood after microwave digestion of the sample. The sample (2 mL human milk or 0.25 mL blood) was introduced into the microwave vessel with 1.5 mL HN03 and 0.25 mL H202 and 300 W (4 min) and 600 W (4 min) were applied. The digestion was completed by heating to 140 C (2-3 h). Se (VI) was reduced to Se (IV) with hydrochloric acid. The instrumental conditions for FI-HAAS (concentrations of reducing agent and carrier acid, flow rate of argon carrier gas, and sample volume injected) were optimized. The detection limit of the proposed method was 0.23 ng/mL (assay) or 115 pg Se (absolute) in biological samples (1.15 ng/mL milk, 10.4 ng/mL blood). The precision values were 5.0% for milk and 4.0% for blood. The accuracy was evaluated with 2 reference materials, National Institute of Standards and Technology Non-Fat Milk Powder (found: 104.3 ± 7.2 ng/g, certified: 110 ± 10 ng/g) and Whole Blood Seronorm (found: 81 ± 7.3 ng/mL, reference: 83 ± 4 ng/mL). The results show the suitability of the method for selenium determination in human milk and whole blood. The method was applied to whole blood samples obtained from pregnant women and to human milk.
Ivermectin Quantitation with an Abamectin Internal Standard
Authors: Reising Kyle P 
Published: February 2020

abstract
The potent antiparasitic ivermectin is detected at low concentrations (ng/g) in liver and muscle tissue by liquid chromatography after conversion to a fluorescent derivative with 1-methylimidazole and trifluoroacetic anhydride. This acetylation reaction can be compromised by residual water that eads to decreased yields. Yields of derivatives of ivermectin and abamectin, a related avermectin, are identical under all circumstances tested. Use of abamectin as an internal standard eliminates derivative yield as a source of analytical variation.
Determination of 4-Hexylresorcinol in Crab Meat
Authors: Smallwood Anthony W , Ranieri Tracy L , Satzger R Duane 
Published: February 2020

abstract
A method is described for determining 4-hexylresorcinol in crab meat. 4-Hexylresorcinol is used to prevent melanosis in shrimp, and the same use has been proposed for crab meat. Because 4-hexylresorcinol may be added illegally to crab meat as a preservative, consumer protection requires that residues of the compound be monitored in crab meat. 4-Hexylresorcinol is extracted from crab meat with acetonitrile. After dilution with water, the extract is passed through a C18 solid-phase extraction column and 4-hexylresorcinol is eluted from the column with ethanol. The compound is determined by reversed-phase liquid chromatography with diode array detection at 206 nm. Limit of quantitation is 1.0 μg/g. Mean recovery in the range 1-20 μg/g is 89%, with a relative standard deviation of 6.3.
Determination of Ivermectin in Salmon Muscle Tissue by Liquid Chromatography with Fluorescence Detection
Authors: Rupp Heidi S , Turnipseed Sherri B , Walker Calvin C , Roybal José E , Long Austin R 
Published: February 2020

abstract
A liquid chromatographic method was developed for determination of ivermectin B1a (IVR) extracted from raw fortified and incurred Atlantic salmon muscle tissues. The method was also used to determine fortified doramectin (DOR) in Atlantic salmon. Tissue extract was applied to a C8 solid-phase extraction (SPE) column, followed by a silica SPE column. Residues in the eluate were treated with trifluoroacetic anhydride and methylimidazole to dehydrate the IVR molecule and form an aromatic fluorescent moiety with a trifluoroacetic ester. This product was subsequently treated with ammonium acetate in methanol to cleave the ester and convert the functional group back to a stable alcohol form. The analytes were determined by fluorescence with excitation at 272 nm and emission at 465 nm. A Cis Hypersil column was used for analysis with a mobile phase of acetonitrile-water (90 + 10, v/v) and an oven temperature of 65°C. IVR and DOR were determined at 5 fortification levels (1, 5,10, 20, and 40 ppb). Intra-assay absolute recoveries ranged from 75 to 89% for IVR and from 73 to 85% for DOR. Relative standard deviations (RSDs) were &lt;7% in all cases. The limit of detection (3 x baseline noise) was 0.25 ppb extracted from tissue. Incurred tissues had an average concentration of 32 ppb, with an RSD of 3%.
Confirmation of Fluoroquinolones in Catfish Muscle by Electrospray Liquid Chromatography/Mass Spectrometry
Authors: Turnipseed Sherri B , Walker Calvin C , Roybal José E , Pfenning Allen P , Hurlbut Jeffrey A 
Published: February 2020

abstract
A multiresidue liquid chromatography/mass spectrometry (LC/MS) confirmation method for fluoroquinolones in catfish muscle was developed by using an electrospray interface. Residues of ciprofloxacin, enrofloxacin, sarafloxacin, and difloxacin were positively identified in catfish muscle fortified at 10-80 ppb as well as in incurred tissue. The extraction procedure is based on an LC method with fluorescence detection for determination of these compounds in catfish. Residues were extracted from catfish muscle with an acidic ethanol solution, and the extracts were cleaned up on a propyl sulfonic acid solid-phase extraction column. Chromatographic conditions were optimized to be compatible with the electrospray interface. Internal electrospray voltages were optimized so that 3 fragment ions, in addition to the protonated molecular ion, could be monitored for each residue. To obtain maximum sensitivity, separate MS acquisition programs were developed for ciprofloxacin/enrofloxacin and sarafloxacin/difloxacin pairs.
Evaluation of Fish Decomposition by Liquid Chromatographic Assay of ATP Degradation Product
Authors: Vallé Michel , Malle Pierre , Bouquelet Stephane 
Published: February 2020

abstract
A liquid chromatographic method is described for quantitative determination of nucleotide derivatives adenosine 5 -triphosphate, adenosine 5 -diphosphate, adenosine 5 -monophosphate, inosine 5 '- monophosphate, inosine, and hypoxanthine in fish. The nucleotide derivatives are extracted by grinding the flesh in cold perchloric acid, recovered, precipitated from the acid by 5M KOH, and analyzed. Nucleotide derivatives and internal standard (purine) were separated in 14 min with a new elution gradient on a reversed-phase column (Kromasil C18) at 25 C. The column was regenerated in 20 min. Regression lines gave strong correlation coefficients. This new method is fast, accurate, and more objective than the Fresh-Tester, acolorimetric determination of a ratio AC used to measure freshness. It shows that the ratio K cannot be used as a universal measure of fish decomposition.
Liquid Chromatographic Method for Analysis of AU-rac-α-Tocopheryl Acetate and Retinyl Palmitate in Soy-Based Infant Formula Using a Zero-Control Reference Material (ZRM) as a Method Development Tool
Authors: Chase G William , Long Austin R , Eitenmiller Ronald R 
Published: February 2020

abstract
A liquid chromatographic method is described for analysis of all-rac-α-tocopheryl acetate, tocopherols, and retinyl palmitate in soy-based infant formula. The vitamins are extracted in isopropyl alcohol and hexane-ethyl acetate without saponification and quantitated by normal-phase chromatography with fluorescence detection. All-rac-α-tocopheryl acetate and retinyl palmitate are quantitated isocratically with mobile phases of 0.5% (v/v) and 0.125% (v/v) isopropyl alcohol in hexane, respectively. Recoveries from zero control reference material soy-based formula averaged 97.2% (n = 25) for retinyl palmitate and 100% (n = 25) for all-rac-α-tocopheryl acetate. Coefficients of variation ranged from 1.21 to 2.86% for retinyl palmitate and from 1.49 to 5.16% for all-rac-α-tocopheryl acetate. The method provides a rapid, specific, and easily controlled assay for analysis of vitamin A and vitamin E in fortified infant formula. Additionally, the method eliminates use of chlorinated solvents.
Liquid Chromatographic Determination of Oxytetracycline in Edible Fish Fillets from Six Species of Fish
Authors: Meinertz Jeffery R , Stehly Guy R , Gingerich William H 
Published: February 2020

Abstract
The approved use of oxytetracycline (OTC) in U.S. aquaculture is limited to specific diseases in salmonids and channel catfish. OTC may also be effective in controlling diseases in other fish species important to public aquaculture, but before approved use of OTC can be augmented, an analytical method for determining OTC in fillet tissue from multiple species of fish will be required to support residue depletion studies. The objective of this study was to develop and validate a liquid chromatographic (LC) method that is accurate, precise, and sensitive for OTC in edible fillets from multiple species of fish. Homogenized fillet tissues from walleye, Atlantic salmon, striped bass, white sturgeon, rainbow trout, and channel catfish were fortified with OTC at nominal concentrations of 10, 20, 100,1000, and 5000 ng/g. In tissues fortified with OTC at 100,1000, and 5000 ng/g, mean recoveries ranged from 83 to 90%, and relative standard deviations (RSDs) ranged from 0.9 to 5.8%. In all other tissues, mean recoveries ranged from 59 to 98%, and RSDs ranged from 3.3 to 20%. Method quantitation limits ranged from 6 to 22 ng/g for the 6 species. The LC parameters produced easily in teg ratable OTC peaks without coelution of endogenous compounds. The method is accurate, precise, and sensitive for OTC in fillet tissue from 6 species of fish from 5 phylogenetically diverse groups.