bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chloramphenicol Extraction from Milk by Using the Diphasic Dialysis Method Followed by Liquid Chromatographic Determination
Authors: Bayo Javier , Moreno Miguel A , Prieta Javier , Díaz Susana , Suárez Guillermo , Domínguez Lucas 
Published: February 2020

Abstract
An economical, fast, and simple method for the extraction and liquid chromatographic determination of chloramphenicol (CAP) in milk is described. CAP is extracted by using a recently developed membrane-based method named “diphasic dialysis.” CAP is detected and quantitated in the organic solvent used in dialysis without additional cleanup steps by reversed-phase liquid chromatography and UV detection (270 nm). The determination imit of CAP in milk was about 5 μg/L, although as little as 1 μg/L could be detected under optimal working conditions.
Liquid Chromatographic Determination of Furazolidone in Shrimp
Authors: Stehly Guy R , Plakas Steven M , El Said Kathleen R 
Published: February 2020

Abstract
A liquid chromatographic (LC) method was developed for the quantitation of furazolidone residues in shrimp muscle. The shrimp homogenate (1.0 g) is extracted with acetonitrile, and the extract is taken to dryness. The residue is dissolved in acetonitrile, and the solution is passed through alumina and C18 cleanup columns. The eluate is taken to dryness and reconstituted in a suitable solvent for reversed-phase (C18) LC with UV detection at 365 nm. Recoveries of furazolidone from shrimp homogenates spiked from 5 to 80 ng/g ranged from 74.3 to 79.7%, and relative standard deviations (RSDs) were 5.0–8.9%. RSDs for incurred furazolidone quantitated at 5.9 and 9.2 ng/g were 6.6 and 7.6%, respectively.
Determination of Total and Free Sulfite in Unstabilized Beer by Flow Injection Analysis
Authors: Bendtsen Anders Broe , Jørgensen Søren Storgaard 
Published: February 2020

Abstract
The AOAC methods for the determination of total and free sulfite by flow injection analysis (FIA) were modified for the analysis of unstabilized beer. Suggested improvements to the methods include stabilizing the sulfite standards with EDTA, changing the FIA manifold to decrease the system dispersion, and using a nonlinear calibration curve. The modifications are simple to implement and provide a more stable, sensitive, and accurate method. The method for the determination of free sulfite is criticized, because the dynamic range of the method is very limited. Analysis of several beer types showed that none exceeded the regulatory limit of 20 ppm sulfite, but several beers contained sulfite without sulfite being declared as an additive by the manufacturer.
Gas Chromatographic Determination of Polychlorinated Biphenyls in Mussels from Galicia, Spain
Authors: Piñeiro Elena Alvarez , Lozano Jesus Simal , Yusty Asuncion Lage 
Published: February 2020

Abstract
We have modified a standard capillary column gas chromatographic method (U.S. Environmental Protection Agency No. 505) for the determination of polychlorinated biphenyl (PCB) residues and applied the technique to mussels (Mytilus galloprovincialis) from Galicia, Spain. During the purification step, SepPak Florisil minicolumns are used instead of conventional columns. Method performance is good (limit of detection, 0.032 μg/kg; recovery, 99%; method precision as coefficient of variation among 10 samples, 2.5%), and compared with the standard method, less eluant is required and analysis is faster. The mean PCB content of 107 mussels collected from various points on the coast of Galicia was 113 μg/kg.
Rapid Ultraviolet Spectrophotometric Assay of Ibuprofen in Liquid Oral Formulations
Authors: Sanyal Asis K , Laha Dinabandhu 
Published: February 2020

Abstract
A selective and sensitive method was developed for rapid estimation of ibuprofen in complex liquid oral formulations. The method is based on spectrophotometry (352 nm) measurement of iodine released by ibuprofen from an iodide-iodate mixture. Absorbance of liberated iodine was linearly related to ibuprofen at concentrations within the range of 10-40 μg/mL. Ibuprofen was made free from interfering excipients and additives through selective extraction with hexane before assay. The results of ibuprofen determination in a syrup and an oral suspension and of recovery experiments performed on various excipients confirmed the applicability of the proposed method to complex formulations.
Determination of Bronopol, Bronidox, and Methyldibromo Glutaronitrile in Cosmetics by Liquid Chromatography with Electrochemical Detection
Authors: Weyland J W , Stern A , Rooselaar J 
Published: February 2020

Abstract
A method for the simultaneous determination of methyldibromo glutaronitrile, bronopol, and broni-dox in cosmetics, based on liquid chromatography with electrochemical detection, is described. The method is suitable for both aqueous products and emulsions. The detection limit is better than 0.002% for all analytes. Recoveries from an emulsion, spiked to concentrations of 0.03% of the analytes, were 100.4% for bronopol [relative standard deviation (RSD), 0.43%], 97.1% for bronidox (RSD, 0.83%), and 98.4% for methyldibromo glutaronitrile (RSD, 1.7%). Repeatabilities were calculated from 10 replicate analyses of commercial samples. The repeatability for bronopol from an emulsion containing 0.047% bronopol was 0.0027% (RSD, 1.99%); for bronidox from a lotion containing 0.027% bronidox, 0.0014% (RSD, 1.86%); and for methyldibromo glutaronitrile from an emulsion containing 0.031% methyldibromo glutaronitrile, 0.0019% (RSD, 2.16%). A ruggedness test showed that sample amount influenced the results for all 3 analytes. The results obtained for bronidox also depended on detection parameters and composition of extraction solvent. The method was applied to 138 cosmetic products and performed trouble free during these analyses. Bronopol was found in 14 samples, and bronidox was found in 4 samples, including a baby hair lotion, in which it is prohibited. Methyldibromo glutaronitrile was present in 27 samples, including creams, lotions, and sun protection cosmetics.
Graphite Furnace Atomic Absorption Method for the Determination of Lead in Sugars and Syrups
Authors: Miller-Ihli Nancy J 
Published: February 2020

Abstract
A method was developed for the determination of lead in sugars and syrups. Samples are wet-ashed with a nitric acid–hydrogen peroxide procedure and analyzed by graphite furnace atomic absorption spectrometry. The method involves the use of magnesium nitrate as a matrix modifier, air ashing, platform atomization, and quantitation by peak area measurements with direct calibration against aqueous standards. The instrumental detection limit (based on 3.29σ) was 10 pg, or 0.5 μg/L for a 20 μL injection, corresponding to a method detection limit of 3.3 ng/g sugar. The characteristic mass was approximately 12 pg. This method was validated by analyzing sucrose and high-fructose corn syrup samples spiked with known quantities of lead. The average recovery was 101 ± 6%.
Hydrolysis of Peptide Binding by Phosphotungstic Acid
Authors: Fialaire Anne , Postaire Eric 
Published: February 2020

Abstract
A new method for the precipitation of protein and oligopeptides is described. In this method, the selectivity of precipitation is a function of the percentage of alcohol. With an 80:20 (v/v) mixture of ethanol and water at room temperature, the selectivity of oligopeptide precipitation was as good as that using phosphotungstic acid.
Liquid Chromatographic Determination of Ivermectin in Feed at the 2-PPM Level: Interlaboratory Study
Authors: Fink David W 
Published: February 2020

Abstract
An analytical method for the determination of ivermectin in feed at the 2 ppm level was evaluated in an interlaboratory study involving 4 laboratories. The method is based on liquid chromatographic measurement following sample preparation by adsorption chromatography on alumina and solid-phase extraction techniques. Each laboratory analyzed 2 complete, final, finished medicated feeds and the corresponding control feeds used in their preparation. In addition, they also measured recoveries in fortified feeds covering 50–150% of the 2 ppm ivermectin use concentration. The mean recoveries from the replicate analyses reported by the laboratories ranged from 90 to 110% and all coefficients of variation (CVs) were less than 4.5%. No significant interferences were found in the control feeds. The pooled distribution of all the individual analytical results (n = 100) gave a mean recovery of 100%, a recovery range of 90–111%, and an overall CV of 5.5%. Resolution of the total variance into its 2 components gave a withinlaboratory CV of 4.1% and a between-laboratories CV of 3.4%. There was no significant difference in recoveries among laboratories, days, concentrations, and feed base or between fortified and medicated feeds (P &gt; 0.2).
Rapid Analysis of Animal Drug Residues by Microcolumn Solid-Phase Extraction and Thermal Desorption–Ion TYap Mass Spectrometry
Authors: Barshick Stacy-Ann , Buchanan Michelle V 
Published: February 2020

Abstract
A new approach was developed for the rapid and quantitative determination of an anthelmintic drug, phenothiazine, in milk. The technique involves a simple extraction procedure using a C18 microcolumn disc, followed by thermal desorption of the analyte from the disc directly into an ion trap mass spectrometer. The compounds are selectively ionized by isobutane chemical ionization and detected by tandem mass spectrometry. With this approach, 10 ppb detection limits were achieved with as little as 100 μL milk and only 10 min of analysis time. This approach was used to analyze samples of milk taken from a cow administered a one-time therapeutic dose of phenothiazine. The target compound could be detected at 56 h post-dosage, corresponding to a concentration of 30 ppb.
Determination of Musk Ambrette in Fragrance Products by Capillary Gas Chromatography with Electron Capture Detection: Interlaboratory Study
Authors: Wisneski Harris H , Yates Ronald L , Havery Donald C 
Published: February 2020

Abstract
A gas chromatographic method that uses an internal standard additions technique is described for the determination of musk ambrette (MA) in fragrance products. A solution containing the product and a known amount of an internal standard, musk tibetene (MT), is injected directly into a gas chromatograph equipped with an electron capture detector. The chromatographic separation of the components on a wide-bore fused silica capillary column is recorded and a response constant is calculated from MA and MT peak heights. A similar response constant is also calculated for a standard solution containing known concentrations of MA and MT. The MA content of the fragrance product is then calculated. Average recoveries of MA from fragrance products ranged from 97.6 to 102.3%. The method was also evaluated collaboratively by 6 laboratories. In this study, the reproducibility relative standard deviation for MA in 6 fragrance test samples ranged from 2.78 to 22.87%.
Determination of Nitrate in Vegetables by Continuous Flow: Interlaboratory Study
Authors: Beljaars Paul R , Duk Remmelt Van , Van Der Horst Geertrutoa M 
Published: February 2020

Abstract
A collaborative study for the determination of nitrate in leafy vegetables, such as endive, lettuce, spinach, and beetroot, by continuous flow (CF) was conducted by the Project Group on Collaborative Studies of the Inspectorate for Health Protection, Food Inspection Service, in The Netherlands. After extraction with water and filtration, samples were cleaned up by dialysis in the CF system. Extracted nitrates were reduced to nitrite in the system by metallic cadmium, and then the nitrite was reacted with sulfanilamide and N-naphthylethylenediamine to form a reddish-purple azo dye. This dye was measured colorimetrically at 530 nm. Fourteen vegetable samples (including 7 blind duplicates) containing nitrate at ca 900 to 5200 mg/kg were analyzed singly by the proposed procedure by 13 laboratories. The data were analyzed by the International Union for Pure and Applied Chemistry (IUPAC)–International Organization for Standardization (ISO)–AOAC protocol for statistics. One collaborator was identified as an outlier for all results. For all samples analyzed, the repeatability relative standard deviation values varied from 1.7 to 5.5%, whereas the reproducibility relative standard deviation values ranged from 3.3 to 5.9%.
Decreasing the Number of Points in the Standard Curve for Determining Iron in Flour: Summary of Collaborative Study
Authors: Martin James I , Soliman Abdel M 
Published: February 2020

Abstract
Seven laboratories participated in a collaborative study conducted to (1) evaluate the effects of reducing the number of points for the standard curve in the AOAC Official Method for iron in flour 944.02A–944.02C(a) from 10 points to 5 points, and (2) compare the levels of iron found in foods by using the 10-point and 5-point standard curves. The 5 points (0.2,0.6,1.0,1.4, and 1.8 μg Fe/mL) were selected by eliminating every other standard point from the 10-point curve after correction for the reagent blank. No differences in the performance parameters between method versions were found when blind duplicate analysis was used to estimate the performance parameters for each sample analyzed. Results from 2 laboratories were excluded from statistical calculations because of failure to follow the specific instructions to increase the dilution when sample absorbance readings exceeded the highest standard point reading. The 5-point standard curve has been adopted first action in method 944.02 by AOAC INTERNATIONAL.
Liquid Chromatographic Determination of the Anticoccidial Drug Halofuginone Hydrobromide in Eggs
Authors: Holland David C , Munns Robert K , Roybal Jose E , Hurlbut Jeffrey A , Long Austin R 
Published: February 2020

Abstract
A liquid chromatographic (LC) method is described for the determination of 5-100 ppb halofuginone hydrobromide (HFG) in eggs. HFG as the free base is extracted from eggs with ethyl acetate. The extract is cleaned up on an acidic Celite 545 column. A Waters C18 column is used for LC separation with UV determination at 243 nm. The isocratic mobile phase is a mixture of water-acetonitrile-ammonium acetate buffer (12 + 5 + 3) and acetic acid. The interassay average recovery from eggs was 90.4%, with a standard deviation of 5.11 and a relative standard deviation of 5.65%.
Enzymatic Determination of Free Carnitine in Milk and Infant Formulas
Authors: Indyk Harvey E , Woollard David C 
Published: February 2020

Abstract
A simple spectrophotometric assay for free carnitine in milk and supplemented infant formulas has been developed. After acid extraction, carnitine is measured enzymatically through its reaction with carnitine acetyltransferase coupled with acetyl coenzyme A and dithiobenzoate (DTNB). The manually performed method is rapid, accurate, and convenient for routine quality-control analysis of infant formulas. The chemistry is also suitable for automation, for greatly enhanced throughput.
Liquid Chromatographic Determination of Benzoic Acid in Orange Juice: Interlaboratory Study
Authors: Lee Hyoung S 
Published: February 2020

Abstract
An interlaboratory study was carried out for the determination of benzoic acid in orange juice by liquid chromatography. The orange juice was fortified with 0.5–10 ppm benzoic acid. Statistical analysis of the results showed that relative reproducibility (RSDR) between laboratories ranged from 6.92 to 15.97% for juice fortified with 1-10 ppm benzoic acid; RSDr was 27.90% for juice fortified with 0.5 ppm benzoic acid. Mean recoveries ranged from 94.5% for 4 ppm benzoic acid to 114% for 0.5 ppm benzoic acid. Total variability increased with increasing fortification level as measured by standard deviation for reproducibility (SR).
Determination of Organochlorine Pesticides in Cheese
Authors: Bentabol Antonio , Jodral Manuela 
Published: February 2020

Abstract
A multiresidue technique was developed for the analysis of 17 organochlorine compounds in cheese: α-hexachlorocyclohexane (α-HCH), β-HCH, γ-HCH, δ-HCH, aldrin, dieldrin, endrin, heptachlor, heptachlor epoxide, chlordane, o,p′-…(o,p′-DDT), p,p′-DDT, o,p′-…(o,p’-DDD), p,p′-DDD, o,p’-… (o,p′-DDE), p,p′-DDE, and the fungicide hexachlo-robenzene. In this technique, the fat, previously extracted from the cheeses, was subjected to 2 cleanup and extraction methods: with H2SO4, for acid-resistant organochlorine pesticides, and with KOH-ethanol. The behavior of the compounds in both treatments enabled us to identify the organochlorine pesticides in cheese. The precision (repeatability and reproducibility) and accuracy of the technique were validated.
Low-Temperature Decomposition of Botanical and Biological Samples for Multielement Analysis by High-Frequency Induced Oxygen–Argon–Fluorine Plasma
Authors: White Ralph T , Lawrence Christopher W 
Published: February 2020

Abstract
The cool plasma asher (CPA) consists of a high-frequency generator and a quartz sample vessel equipped with a cooling finger that prevents loss of volatile elements. After sample decomposition within an O2–Ar–F plasma, the ashing residues and the elements condensed on the surface of the vessel or cooling finger are dissolved by refluxing in 1–5 mL of double-distilled acid. The sample solutions are analyzed for elemental content by inductively coupled plasma-atomic emission spectrometry (ICP–AES). The recovery values for 42 elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Eu, Fe, Hg, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Pd, Pt, Rb, S, Sb, Se, Sn, Sr, Te, Ti, V, Y, Yb, Zn, Zr, La, Au, and Sc) are documented after cool plasma ashing of elemental spectrometric standards. In addition, NIST Standard Reference Materials consisting of botanical and biological samples are ashed by CPA, and results are reported for 23 elements (Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, S, Se, Sr, V, and Zn) analyzed by ICP-AES. This method achieves good recoveries for many elements while allowing decomposition of difficult sample matrixes without acid, at a temperature slightly above 100°C. We investigated several ashing facilitators to improve ashing efficiency. This paper describes improved ashing conditions due to sample agitation, gas mixtures, Teflon balls, and a Teflon vessel. The time required to ash 1.0 g of botanical sample in the CPA was reduced from 80 h with no ashing aids to 3 h with maximum ashing aids. The optimum plasma ashing conditions for 1.0 g of sample was 6 h at a high-frequency power of 30 W with a 1 h acid reflux to dissolve sample ash. Because reflux acid in the final sample volume was minimal, trace elemerits were concentrated and blank contamination was extremely low.
Determination of Total Nitrogen in Urine by Pyrochemiluminescence: Collaborative Study
Authors: Boehm Kristi A , Ross P Frank 
Published: February 2020

Abstract
Twelve collaborating laboratories analyzed 5 blind duplicate samples of human urine for total nitrogen using a pyrochemiluminescence method. The nitrogen content ranged from low (650 mg/L) to high levels (8800 mg/L) in urine samples of people under moderate to severe stress. In addition to test samples, collaborators also received a certified standard (sodium nitrite in water) as an external control. The pyrochemiluminescence assay was performed on urine samples diluted in water within a range of 1:50 to 1:100. The method detects total nitrogen by reaction of the product of high temperature oxidative pyrolysis and ozone. Repeatability standard deviation values (RDSr) ranged from 1.49 to 3.91% and reproducibility standard deviation values (RSDR) ranged from 3.66 to 9.57%. The average recovery of total nitrogen was 99.9%. The pyrochemiluminescence method for determination of total nitrogen in urine was adopted first action by AOAC INTERNATIONAL.
Determination of Residues of Flumequine and Nalidixic, Oxolinic, and Piromidic Acids in Catfish by Liquid Chromatography with Fluorescence and UV Detection
Authors: Munns Robert K , Turnipseed Sherri B , Pfenning Allen P , Roybal José E , Holland David C , Long Austin R , Plakas Steven M 
Published: February 2020

Abstract
A liquid chromatographic (LC) method is described for determining residues of flumequine (FLU) and nalidixic (NAL), oxolinic (OXO), and piromidic (PIR) acids in catfish muscle. The identities of 3 of these residues are confirmed by gas chromatography–mass spectrometry (GC–MS). The extraction and cleanup procedures are the same for both determination and identification. Analyte isolation involves homogenizing the tissue with acetone, defatting the acetone extract with hexane, and extracting the compounds into chloroform. The extract is further purified by first partitioning into base and subsequently back-extracting into chloroform after acidifying the aqueous phase. After the solvent is evaporated, the residue is dissolved in mobile phase, and the analytes are determined by LC with fluorescence detection, excitation at 325 nm and emission at 365 nm. Catfish muscle was fortified with each quinolone at 5,10,20,40, and 80 ng/g. Overall average recoveries were 83–94%, with relative standard deviations (RSDs) of 5–7%. The method was evaluated also by a second analyst, who determined 4 quinolones added in combination. Average recoveries of quinolones from catfish fortified at 5,10, and 20 ng/g were 78–90%, with RSDs of 3–6%. The presence in catfish muscle of incurred OXO, FLU, and NAL at the 10 ng/g level was confirmed by analyzing the decarboxylated quinolones by GC–MS. The relative abundances of all 5 major ions for OXO, FLU, and NAL were within 10% of those observed in spectra of standard compounds decarboxylated by the same method.
Survey of Trihalomethanes and Other Volatile Chemical Contaminants in Processed Foods by Purge-and-Trap Capillary Gas Chromatography with Mass Selective Detection
Authors: Mcneal Timothy P , Hollifield Henry C , Diachenko Gregory W 
Published: February 2020

Abstract
A limited number of soft drinks, juices, beers, and waters from processed vegetables were analyzed for trihalomethanes (THMs), benzene, and toluene by a modified Environmental Protection Agency (EPA) Method 524.2. The THMs, which include chloroform, bromodichloromethane, dibromochloromethane, and bromoform, are reaction by-products of water disinfection by chlorination. EPA Method 524.2 is a purge-and-trap capillary gas chromatographic method based on mass spectrometric detection which identifies and simultaneously measures purgeable volatile organic compounds in drinking water. Chloroform was present at concentrations ranging from none detected to 94 ng/g in the 44 foods analyzed. Bromoform was not found in any of the products at a detection limit of 0.1 ng/g. Residue levels of the other THMs ranged from none detected to highs of 12 and 2 ng/g for bromodichloromethane and drbromochloromethane, respectively. Benzene residues were typically &lt;5 ng/g, except for 7 and 9 ng/g in 2 foods. Toluene residues were typically ≤3 ng/g except for 23,29, and 75 ng/g in 3 canned foods.