bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas-Solid Chromatographic Determination of Oxygen in Various Pharmaceutical Products
Authors: Lyma Gary W , Johnson Raymond N , Kho Boen T
Published: February 2020

A method is described for the gas chromatographic determination of oxygen at the low part per million level in both aqueous systems and nonaqueous systems such as creams, oils, and waxes. This method offers advantages over other popular assay procedures such as the Winkler and polarographic methods. The purging technique developed can be applied to any liquid or solid with a melting point of 75μC or less. Oxygen purged from the sample is passed through a molecular sieve 5A column where it is separated from nitrogen. Peaks obtained are compared to similarly prepared oxygen standards. The method is simple enough to be used routinely and up to 15 samples can be analyzed per day.
High Pressure Liquid Chromatographic Determination of β-Sitosterol and β-Sitosterol-D-Glucoside in Whisky
Authors: Byrne Kevin J , Reazin George H , Andreasen Arthur A
Published: February 2020

A high pressure liquid chromatographic method is presented for determining the oak wood steroids, β-sitosterol and β-sitosterol-D-glucoside, which contribute to floe formation in whisky. The steroids are extracted from whisky by using an adsorbent resin, Amberlite XAD-2, and are detected at 210 nm, orarederivatized to 2,5-dinitrobenzoate esters which are detectable over a wide ultraviolet wavelength range. Detection limits were less than 0.1 ppm for β-sitosterol and less than 0.2 ppm for β-sitosterol-D-glucoside in most whiskies, using the extraction procedure described. When the steroids were derivatized, the detection limits were decreased by about a factor of 10.
Simplified Automated System for Determination of Vitamin A in Milk
Authors: Giuliany Barbara E
Published: February 2020

A simplified automated system for the determination of vitamin A in milk has been developed to eliminate backpressure and cleaning problems previously experienced. A more specific primary optical filter has also been used.
Comparison of Radioimmunoassay and Enzyme-linked Immunosorbent Assay for Determining Aflatoxin M1 in Milk
Authors: Pestka James J , Li Yaguan , Harder William O , Chu Fun S
Published: February 2020

Using a highly specific antibody against aflatoxin Mi, a radioimmunoassay (RIA) and an enzyme-linked immunosorbent assay (ELISA) were developed for the quantitation of Mi in milk. RIA was sensitive in the range of 5-50 ng per assay but was subject to interference by whole milk. Extraction and cleanup were therefore necessary for the detection of M1 in milk at 0.5 ng/mL. An ELISA procedure was developed by using an aflatoxin M1-carboxymethyl-horseradish peroxidase conjugate as the ligand. Competitive assays revealed that this system was relatively more sensitive for M1 than for B1, and had a much lower degree of cross-reactivity for aflatoxins B2, G1, G2, B2a, and aflatoxicol. As low as 0.25 ng M1/mL in artificially contaminated milk (raw, whole, skim) could be detected by ELISA in 3 h without extraction or cleanup. Because of its simplicity, sensitivity, and specificity, ELISA is the preferred method for monitoring aflatoxin M1 in milk.
High Pressure Liquid Chromatographic Method for Determination of Polynuclear Aromatic Hydrocarbons in Beer
Authors: Joe Frank L , Roseboro Emma L , Fazio Thomas
Published: February 2020

A high pressure liquid chromatographic (HPLC) method has been developed for the determination of some polynuclear aromatic hydrocarbons (PAHs) in beer. The PAHs are extracted into isooctane from a beer sample to which sodium hydroxide, ethanol, and acetone have been added. The isooctane extract is washed with acid and then base, and is purified by chromatography through deactivated neutral alumina. The eluate from the column is concentrated to dryness and the resulting residue is dissolved in methanol-acetonitrile (1 + 1) and subjected to reverse phase HPLC analysis. Both ultraviolet (UV) and fluorescence detectors are used to monitor the HPLC column effluent. Recovery of 4 PAHs, benz(a)anthracene, benzo(a)pyrene, benzo(g,h,i)perylene, and dibenzo(a,i)pyrene, ranged from 77 to 108% by UV measurement and 73 to 97% by fluorescence measurement.
Near-Infrared Reflectance Determination of Fat, Protein, and Moisture in Fresh Meat
Authors: Kruggel William G , Field Ray A , Riley Melvin L , Radloff Harold D , Horton Kristiina M
Published: February 2020

Near-infrared spectral absorption properties were determined for emulsified and ground meat samples. Six corrected log numbers associated with the optical responses of 6 filters in the InfraAlyzer were used as multiple independent variables in regression equations. Dependent variables for the equations were moisture, determined by oven-drying; fat, determined by Goldfisch extraction; and protein, determined by the Kjeldahl method. InfraAlyzer log values, replicated 4 times on each emulsified beef sample and 3 times on each ground lamb sample, increased as the samples were warmed from the heat generated in the sample drawer. Variation in temperature of the meat samples was partially responsible for differences in constant terms and in regression coefficients for equations developed on data from different replications of a sample. Multiple correlation coefficients for fat ranged from 0.91 to 0.94 in emulsified meat and from 0.83 to 0.85 in ground meat; for moisture, 0.90-0.94 and 0.83-0.85, respectively; and for protein, 0.80-0.85 and 0.72-0.77, respectively. Overall, near-infrared reflectance shows promise as a rapid method for determining composition of meat. Nevertheless, some aspects of near-infrared reflectance require further attention.
High Pressure Liquid Chromatographic Determination of Aldicarb, Aldicarb Sulfoxide, and Aldicarb Sulfone in Potatoes
Authors: Cochrane William P , Lanouette Monique
Published: February 2020

An ion-suppression reverse phase high pressure liquid chromatographic method is described for the determination of aldicarb, aldicarb sulfoxide, and aldicarb sulf one in potatoes. Samples are extracted with methylene chloride and Na2SO4, evaporated to dryness, and cleaned up using Sep-Pak silica and Sep-Pak-C18 cartridges. The extract can be successfully analyzed by high pressure liquid chromatography on either a μLiChrosorb RP-18 or μBondapak C18 column and quantitated using a variable wavelength ultraviolet detector set at either 220 or 247 nm. The mobile phase is acetonitrile-buffer (4 + 96) and (30 + 70), buffered to pH 7.6 and flowing at 2 mL/min. Recoveries ranged from 80 to 100%. The minimum detectable amount was 37.5 ng, which easily permitted the quantitation of 0.1 ppm aldicarb sulfone in 75 g sample. The recovery of aldicarb was low because of its rapid enzymatic oxidation to aldicarb sulfoxide and sulfone.
Paper and Micro Thin Layer Chromatographic Methods for Determination of Mercuric Chloride and Detection of Copper Sulfate
Authors: Nanda Kumar Nanguneri V , Devi Yalavarthi Prameela
Published: February 2020

A new simple, sensitive, and rapid method is described for the qualitative and quantitative determination of mercuric chloride by paper chromatographic-enzymatic and micro thin layer chromatographic-enzymatic methods. Mercuric chloride is detected by succinate dehydrogenase inhibition using 2-(4-iodophenyl)-3-(4-nitrophenyl) 5-phenyltetrazolium chloride and N-methylphenazonium methosulfate as the chromogenic reagent. From 0.5 to 5μg mercuric chloride may be estimated, and 50 ng may be detected. The method can be used for the quantitative determination of mercuric chloride in fresh and sea water without cleanup and for the detection of copper sulfate.
General Method for Determination of Pesticide Residues in Samples of Plant Origin, Soil, and Water. II. Thin Layer Chromatographic Determination
Authors: Ambrus Árpád , Hargitai Éva , Károly Gabriella , Ambrus András Fülöp , Ambrus János Lantos
Published: February 2020

o-Tolidine plus KI, p-nitrobenzene-diazoniumfluoroborate, bioassay with fungi and enzyme sources, AgNO3 plus UV radiation, and p-dimethyl-aminobenzaldehyde modes of detection have been selected for TLC screening of pesticide residues in extracts of samples of unknown origin. Single solvents were used for the elution. Coefficients of variation of Rf values were studied as a function of Rf and eluants. Indicator compounds were used for controlling the proper conditions of detection. The detectability of 188 pesticide compounds was tested, and the minimum detectable amounts were determined.
Brine Saturation Technique for Extraction of Light Filth from Rubbed and Ground Sage: Intralaboratory Study
Authors: Freeman Clarence C
Published: February 2020

An intralaboratory study was made of a new and widely applicable technique for isolating light filth from rubbed and ground sage. The technique eliminated the hazardous, costly, and lengthy pretreatment and isolation procedures of the current methodology and resulted in considerably better recoveries. Overall recovery of all filth elements introduced as spikes was 99.3% on the first trapping. The basic principle of the procedure is product saturation with brine, followed by trapping of the filth elements from tap water with olive oil.
High Pressure Liquid Chromatographic Determination of Methyl and Propyl p-Hydroxybenzoates in Comminuted Meats
Authors: Perfetti Gracia A , Warner Charles R , Fazio Thomas
Published: February 2020

A method was developed for determining methyl and propyl p-hydroxybenzoates (methyl and propyl parabens) in comminuted meats. The parabens were extracted from the meat sample with acetonitrile. After filtering, the extract was analyzed by reverse phase high pressure liquid chromatography, using a 254 nm absorbance detector. Samples of bologna, chicken roll, and chopped ham were fortified with approximately 100,200, and 400 ppm of each paraben. Average recoveries were 92% for methyl paraben and 94% for propyl paraben.
Separation and Characterization of Standard Propoxyphene Diastereomers and Their Determination in Pharmaceutical and Illicit Preparations
Authors: Soni Shiv K , Gelder Daniel Van
Published: February 2020

Due to the existence of 2 asymmetric carbon atoms in: the propoxyphene molecule, there are 4 diastereomers: alpha dextro, alpha levo, beta dextro, and beta levo. Only α-d-propoxyphene is included under the federal Controlled Substances Act. Baseline separations of propoxyphene from various incipients (aspirin, caffeine, phenacetin, and acetaminophen) present in pharmaceutical and illicit preparations, and between the alpha and beta diastereomers, were achieved by high pressure liquid chromatography. The column eluant was collected and propoxyphene was extracted. The optical isomers were differentiated and characterized by melting points and by chemical microcrystalline tests. Using hot stage thermomicroscopy, the eutectic melting points of binary isomeric mixtures of propoxyphene bases and salts were found to be depressed about 10° and 15-30°C, respectively, below the individual isomer melting points. The characteristic microcrystals formed with the alpha racemic mixtures by using a glycerin-aqueous gold chloride reagent were not produced by the beta racemic mixtures.
Evaluation of Laboratory Performance with Aflatoxin Methods by Means of the AOCS Smalley Check Sample Program
Authors: Mckinney John D
Published: February 2020

The American Oil Chemists’ Society Smalley Check Sample Program offers ongoing check sample series for determination of aflatoxins in peanut meal, cottonseed meal, and corn meal. Laboratories participating in this program represent a worldwide cross section of industry, regulatory, and commercial laboratories. Each annual series presently consists of 7 samples including a solution of an unknown mixture of aflatoxins B1, B2, G1, and G2 for direct spotting and quantitation. Participant analyses of the solution of aflatoxins resulted in coefficients of variation generally higher than those of any sample. Comparison of 4 years of results for analysts using BF and CB methods of analysis for peanut meal samples with aflatoxin B1 levels ranging from 2 to 56 ng/g resulted in higher aflatoxin B1 results for the CB method. The number of participants reporting results by HPLC methods is small; however, their results compare closely with those using TLC methods.
Rapid, Economical Method for Determination of Aflatoxin and Ochratoxin in Animal Feedstuffs
Authors: Roberts Basil A , Glancy Edward M , Patterson Deryck S P
Published: February 2020

A quantitative procedure widely used in European Economic Community (EEC) countries has been successfully scaled down to produce a rapid method for determination of af latoxin B1 (and other anatoxins) in animal feeds. Without modification, the method may be used for simultaneous ochratoxin A determination in simple feeds, but a slightly different extraction procedure is required for compound feeds. Validity of the method has been demonstrated by comparison with the full EEC procedure for aflatoxin B1 and the Nesheim method for ochratoxin A. Analyses may be completed within 2 h and there is a considerable savings in materials over the 2 reference methods. The procedure is also less hazardous because volumes of toxic extract are small, and the operator is exposed to minimum solvent vapor.
Determination of Aflatoxins in Animal Tissues
Authors: Stubblefield Robert D , Shotwell Odette L
Published: February 2020

A method for the determination of aflatoxins in animal tissues has been developed, and applied successfully to beef, swine, chicken, and human livers, and to beef kidney, heart, spleen, muscle, and blood. Blended tissue is denatured with citric acid and extracted with dichloromethane on a wrist-action shaker. After filtration, the extract is partially purified on a silica gel column, and aflatoxins B1 and M1 are determined by 2-dimensional thin layer chromatography and densitometry. Recoveries of Bi and Mi added to meat tissues and blood were approximately 90 and 80%, respectively. The method gave results for a contaminated freeze-dried liver comparable to analyses by 3 other published meat tissue methods. The method is rapid and has a determination limit ≤0.1 ng/g. In addition, the method uses less toxic and smaller quantities of solvents and chemicals.
Rapid Screening Method for Aflatoxin M1 in Milk
Authors: Holaday Charles E
Published: February 2020

A rapid screening method for detecting aflatoxin M1 in milk has been developed, based on minicolumn chromatography and requiring 8-10 min for each test. The minicolumn is packed with dry Florisil (100-200 mesh) on the bottom, anhydrous Na2S04 as the next layer, topped with neutral alumina (70-200 mesh) to which 8% water (wet basis) has been added. A blue fluorescent band at the Florisil-Na2SO4 interface indicates the presence of aflatoxin M1. The limit of detection is estimated to be about 0.2 μg/kg. Because several items are disposable, both the time to maintain glassware and the cost per determination are reduced.
Improved Fluorometric-Iodine Method for Determination of Aflatoxin in Corn
Authors: Davis Norman D , Guy Mary L , Diener Urban L
Published: February 2020

Several innovations in the fluorometric-iodine (FL-I) method for determining aflatoxin in corn made the procedure faster and more convenient than the original method. Ground corn was packed into a chromatographic column and the aflatoxins were extracted with methylene chloride. Sep-Pak C18 cartridges were used for sample cleanup. A 5 min thin layer chromatographic slide analysis confirmed the presence of aflatoxin, which was quantitated by f luorometric determination of the iodine derivative of aflatoxin B1.
Effect of Bentonites on Fluorometric Selenium Determination
Authors: Olson Oscar E , Herr Ailene A , Palmer Ivan S
Published: February 2020

Bentonites in feeds cause error in the analysis for Se by the AOAC (3.097-3.101) fluorometric method for Se in plants. The error apparently results from the binding of the piazselenol by insoluble residue from the bentonite. This effect is avoided by diluting digests to volume after reduction with HCl, centrifuging or allowing to stand, and analyzing a portion of the clear supernatant liquid. Insoluble residues present after digestion of plant materials do not appear to cause a similar error.
Degradation of Methomyl Residues in Frozen Strawberries
Authors: Wheeler Willis B , Thompson Neal P , Edelstein Robert L , Krause Richard T
Published: February 2020

14C-Methomyl (S-methyl N-[(methylcarbamoyl)-oxy]thioacetimidate) suspended in a commercial formulation was sprayed on strawberries. At 7 and 14 days post-application, mature berries were harvested and chopped. Fresh chopped berries were extracted with methanol using a Polytron homogenizer, and the crop marc was subsequently leached with methanol, freeze-dried, and re-extracted. Portions of the fresh chopped fruit were also frozen at −20°C for 1,30, and 120 days before extraction with methanol using a Polytron homogenizer, followed by subsequent leaching of the crop marc. For fresh berries, 93.7 and 88.9% of the 14C present at harvest was extractable at 7 and 14 days post-application, respectively. Based on thin layer chromatographic analysis, methomyl represented 83.5 and 68.2% of the 14C extracted from fresh berries at 7 and 14 days, respectively. Freezing of strawberries reduced extraction efficiency and appeared to degrade methomyl. At 7 and 14 days post-application, averages of 80.9 and 77.1%, respectively, of the 14C present were extractable after frozen storage regardless of storage time. Furthermore, only about 10% of the extracted 14C was methomyl; the remainder was of unknown composition.
Gas-Liquid Chromatographic Method for Determining Oxamyl in Peppers, Tomatoes, and Cucumbers
Authors: Greenberg Rachel S
Published: February 2020

A simple and fast gas-liquid chromatographic method has been developed to determine residues of oxamyl insecticide in peppers, tomatoes, and cucumbers. Following sample extraction with ethyl acetate and cleanup on an alumina column, the compound is determined using a thermionic nitrogen-phosphorus detector. The limit of detection is 0.02 ppm based on a 40 g sample. Average recoveries for oxamyl at 0.025-1.0 ppm for all 3 products were 88-97%.
Gas Chromatographic-Mass Spectrometric Characterization of an Alteration Product of Malathion Detected in Stored Rice
Authors: Hansen Lydell B , Castillo Gabriel D , Biehl Edward R
Published: February 2020

Four alteration products of malathion have been observed in crop extracts of rice, which may not be readily identifiable in a typical gas chromatographic-mass spectrometric (GC-MS) analysis of the residues. Extracts of rice containing malathion and several related compounds were analyzed on gasliquid chromatographic (GLC) columns of different polarities. The methyl ethyl succinate ester of malathion co-elutes with malaoxon from a nonpolar GLC column. Retention data and GC-MS analysis indicate the presence of 3 previously reported compounds. Evidence was obtained for a fourth compound, O-methyl O-ethyl S-(l,2-bis-carbethoxy) ethyl phosphorodithioate, apparently resulting from the environmental alteration of malathion.
Care of Reverse Phase High Performance Liquid Chromatographic Columns When Injecting Extracts of Fat- or Oil-Based Preparations
Authors: Rabel Fredric M
Published: February 2020

When analyzing extracts of pharmaceutical preparations, the chromatographer may place some of the base fats or oils onto the reverse phase analytical column with each injection. This is not a problem if they are washed free from the column periodically. If not cleaned off the column, column efficiency and selectivity can be lost forever. A simple procedure is described for washing columns.
Automatic Karl Fischer Titration of Moisture in Grain
Authors: Jones Frank E , Brickenkamp Carroll S
Published: February 2020

Automatic Karl Fischer titrators of the motor-driven buret type and the coulometric generation type were applied to the determination of moisture in grain. Techniques were developed to optimize the performance of the Karl Fischer titration method and to overcome disadvantages attributed to it. The imprecision (1 standard deviation) of a determination is typically 0.06% moisture content at a moisture content of 15%; the systematic uncertainty from known sources is estimated to be ±0.05% moisture content at a moisture content level of 15%. It is suggested that the method be designated as the primary reference method for grain in general and for corn and soybeans in particular.
Determination of Internal Insect Infestation of Wheat: Collaborative Study
Authors: Trauba Richard L
Published: February 2020

An improved method has been developed for determining internal insect infestation of wheat kernels. The method involves acid hydrolysis of cracked wheat, wet sieving to remove the acid, transferring to a 2 L Wildman trap flask, deaeration by boiling, and treatment with Tween 80-Na4EDTA. Insects are extracted with light mineral oil. Reports from 6 collaborators showed that recovery was 95.92% for adult insect heads and 97.22% for larvae by the proposed method as compared with 87.05% and 6.12%, respectively, by the official method. The method has been adopted official first action.
Westphal Plummet Determination of Alcohol in Distillates
Authors: Alvarez-Nazario Fabián
Published: February 2020

A new table gives the percent alcohol by volume in distillates from density values obtained at room temperature by using a Westphal plummet.
Liquid Chromatographic Separation of Some Alkylaminocyclohexanecarbonitriles from Phenylcyclohexylamines Related to Phencyclidine
Authors: Wall George M , Clark C Randall
Published: February 2020

The synthesis of five 1-aminocyclohexanecarboni-Iriles and the corresponding 1-phenylcyclohexylamines related to phencyclidine is reported. The compounds are separated by reverse phase liquid chromatography in an acidic methanol-water solvent system.
Comparison of Yeast and Mold Counts by Spiral, Pour, and Streak Plate Methods
Authors: Zipkes Marilyn R , Gilchrist James E , Peeler James T
Published: February 2020

Foods with naturally occurring yeast and mold were used in a comparative study of 4 plating techniques. Oats, green beans, and cheese were incubated for 3 and 5 days at 25°C. Although 3 days of incubation would be sufficient for yeast, 5 days were necessary for the mold count. The percent recovery of yeasts and molds by the spiral and streak methods ranged from 200 to 357% compared with the pour plating method described in the Bacteriological Analytical Manual (BAM). The spiral method had the highest overall recovery and the lowest replicate plating error.
Gas-Liquid Chromatographic Method for Analysis of Pentachloronitrobenzene Formulations: Collaborative Study
Authors: Hanks Alan R
Published: February 2020

A collaborative study has been conducted on a gasliquid chromatographic (GLC) method for determining pentachloronitrobenzene (PCNB) in formulations. Wettable powder, liquid, and granular matched pairs of commercial products were analyzed by 17 laboratories using peak height measurements and by 12 laboratories using integrator area measurements. Samples were dissolved in chloroform and aliquots were mixed with internal standard before GLC analysis on a 5% SE-30 column. Mean coefficients of variation for the completed study were 1.54% for integrator area measurements and 1.35% for peak height measurements. The method has been adopted official first action.
Comparison of Enzymic, Gas-Liquid Chromatographic, and High Performance Liquid Chromatographic Methods for Determining Sugars and Organic Acids in Strawberries at Three Stages of Maturity
Authors: Reyes Felix G R , Wrolstad Ronald E , Cornwell Christopher J
Published: February 2020

Free sugars and major nonvolatile organic acids present in strawberries at 3 degrees of ripeness were determined by 3 analytical methods: enzymic, gasliquid chromatographic, and high performance liquid chromatographic. Results showed that variability in sugar composition due to both degree of ripeness and method of analysis was greater for sucrose than for glucose and fructose. Sucrose was almost completely hydrolyzed in the overripe fruit. Acid results showed that there was little variation in citric acid levels due to ripeness or method of analysis; malic acid, however, decreased greatly in overripe fruit. Malic acid also showed high variability due to method of analysis. The glucose:fructose ratios for the underripe, ripe, and overripe fruit were 0.86,0.92, and 0.60, respectively. The citric:malic ratios were 1.58, 2.39, and 14.86 for the underripe, ripe, and overripe stages, respectively.
Gas Chromatographic- Atmospheric Pressure Active Nitrogen Method for Organomercury Speciation in Environmental Samples
Authors: Rice Gary W , Richard John J , D'Silva Arthur P , Fassel Velmer A
Published: February 2020

Methods are presented for the determination of methylmercury in fish, water, urine, and sediments, and diorganomercury compounds in water. Two significant differences from previous methods are the use of methylene chloride extracting solvent which permits sample extracts to be concentrated to volumes as low as 0.1 ml, and use of a gas chromatograph interfaced to an atmospheric pressure active nitrogen (APAN) afterflow detector. Such a detector is very sensitive and selective for Hg at picogram levels. Thus, limits of detection were significantly enhanced.
Polarographic Determination of Kjeldahl Nitrogen
Authors: Fosdick Lawrence E , Pike Richard K
Published: February 2020

A simple and rapid method is described for determining ammonia content of a Kjeldahl digest by polarography. The digest is diluted and pipetted into a solution of formaldehyde in an acetate buffer. The hexamethylenetetramine produced by reaction between ammonia and formaldehyde is determined electrochemically at μ1.04 V. Three different samples (milk, bread, and cashews) were analyzed and Kjeldahl nitrogen showed an average relative standard deviation of 3.4%; repetitive analyses of the same digest demonstrated a relative standard deviation of 1.5%.
High Pressure Liquid Chromatographic Determination of Monoand Disaccharides in Presweetened Cereals: Collaborative Study
Authors: Zygmunt Lucian C ,   Collaborators:, Anderson E , Behrens B , Bowers R , Bussey M , Cohen G , Colon M , Deis C , Given P S , Granade A , Harms C , Heroff J C , Hines D , Hung G W , Hurst W J , Keller J , Laroche F B , Luth W , McKay D , Mertle T , Navarre M , Rivera R , Scopp R , Scott F , Sherman R , Sloman K , Sodano C , Trick K D , Vandine B R , Webb N G
Published: February 2020

A collaborative study was conducted using a modified AOAC method (sugars in chocolate) for the determination of fructose, glucose, sucrose, and maltose in presweetened cereals by high pressure liquid chromatography (HPLC). Eight samples consisting of 6 products were analyzed in duplicate by the HPLC method and the AOAC Lane-Eynon method. The AOAC method was modified to use water-alcohol (1 + 1) and Sep-Pak C18 cartridges for sample cleanup. The HPLC results indicate precision comparable to the Lane-Eynon method and the chocolate method. The modified HPLC method has been adopted official first action.
The Next Decade: Sound Methodology and Legal Actions
Authors: Levine Arthur N
Published: February 2020

Regulatory agencies become involved in numerous "legal actions." Not only do these agencies initiate legal actions to enforce laws, they promulgate rules, issue statements of policy, and develop and define statutory standards. Not surprisingly, these programs are challenged in courts by members of regulated industry, trade associations, consumer groups, and individual citizens. Regulatory agencies also initiate and respond to a variety of issues by administrative, rather than judicial, action. These too are "legal actions" and frequently concern the adequacy of laboratory and scientific methodology. Where the agency initiates action to enforce the law, it carries the burden of proof. Where agency action or inaction is challenged, the challenging party carries the burden of proof and the courts have frequently given great deference to the views of the agency. However, the courts will frequently evaluate for themselves the scientific basis for the agency’s decision, regulation, or program. Examples of judicial reaction to scientific questions in recent years will be discussed.
Simultaneous Determination of Vitamins A and D in Dosage Forms by High Pressure Liquid Chromatography
Authors: Ines Maria , Santoro R M , Magalhães João F , Hackmann Erika R M
Published: February 2020

Vitamins A and D were determined simultaneously in oily solutions, ointments, and elixirs, but only vitamin A could be determined in capsules. Samples were saponified with KOH in isopropanol-water, using hydroquinone as antioxidant, and extracted with ether-petroleum ether (1 + 1). After evaporation of solvent, residues were dissolved in isopropanol. Vitamins in these solutions were determined by reverse phase high pressure liquid chromatography, using methanol-water as mobile phase and detection at 254 nm. The reproducibility, using external standards, was 1.6-2.5% and 1.2-3.8% for vitamins A and D, respectively.
Identification and Confirmation of Pyrantel- and Morantel-Related Residues in Liver by Gas Chromatography-Mass Spectrometry with Selected Ion Monitoring
Authors: Lynch Martin J , Bartolucci S Richard
Published: February 2020

A gas chromatographic-mass spectrometric method with selected ion monitoring (GC/MS-SIM) is described for identification of pyrantel- and morantel- related residues in swine and beef liver. Alkaline hydrolysis of tissue liberates and converts pyrantel-and morantel-related residues to 3-(2-thienyl)-acrylic acid (TAA) and 3-(3-methyl-2-thienyl)-acrylic acid (MTAA), respectively. These thienyl acrylic acids are recovered by ion exclusion chromatography and converted to methyl ester derivatives (TAAE and MTAAE) for identification by GC/MS-SIM. When the relative intensities of the molecular ion, the base peak, and a third significant ion of the sample correspond to ion intensities of the preformed or processed standards, the identity of the residue is confirmed. The method was validated by analysis of swine and beef liver samples containing incurred residues of pyrantel and morantel under withdrawal conditions.
Factors Affecting the Determination of Citrate-Insoluble Phosphorus
Authors: Johnson Frank J , Farley James A
Published: February 2020

Interlaboratory imprecision of results for citrate-insoluble P2O5 is greater than desired, especially for analyses of triple superphosphate (TSP). A systematic study of the method indicates that the most significant contributor to the imprecision is the fineness of the ground sample. Other factors affecting results are sample weight, bath temperature, and extraction time. Comparable results are reported for TSP analyzed by the AOAC official method on samples prepared by grinding to –20 + 200 mesh, on unground samples, and on samples disintegrated by an ultrasonic bath. Similar tests on diammonium phosphate, using the same 3 sample preparation techniques, yield results that are not comparable.
High Pressure Liquid Chromatographic Determination of Aflatoxins in Peanut Butter Using a Silica Gel-Packed Flowcell for Fluorescence Detection
Authors: Francis Octave J , Lipinskl Leo J , Gaul Jean A , Campbell Alfred D
Published: February 2020

A high pressure liquid chromatographic method has been developed for determining aflatoxins B1, B1 G1, and G2 in peanut butter. The method is based on extraction with acidified aqueous methanol, partition of the aflatoxins into methylene chloride, and purification of the extract on a 2 g silica gel column. The extracted aflatoxins are resolved on a microparticulate (10 μm) porous silica gel column in ca 10 min with a water-washed chloroform-cyclohexane-acetonitrile solvent that contains 2% isopropanol. The fluorescence detection system determines aflatoxins B1, B2, G1, and G2 at low levels, i.e., 0.25 ppb B1, 0.5 ppb G1, and 0.2 ppb B2 and G2. Multiple assays of 5 samples of naturally contaminated peanut butters containing total aflatoxins (B1 + B2 + G1 + G2) at levels of 1,2,3, 9, and 17 ppb gave intralaboratory coefficients of variation of 7,4,4,11, and 3%, respectively. Samples spiked at levels of 5, 9, and 17 ppb total aflatoxins showed recoveries of 79, 81, and 81%, respectively.
Terbufos and Its Metabolites: Identification by Gas-Liquid Chromatography and Mass Spectrometry
Authors: Wei Lester Y , Felsot Allan S
Published: February 2020

Methods have been developed for identification of terbufos, terbufos sulfoxide, terbufos sulfone, terbufoxon, terbufoxon sulfoxide, and terbufoxon sulfone by mass spectrometry. Residues of terbufos and terbufos sulfone fortified in soil samples at 5 ppm were extracted and analyzed successfully by gas chromatography and mass spectroscopy.
Rapid Screening Test for Sulfamethazine in Swine Feeds
Authors: Schwartz Daniel P
Published: February 2020

A simple, 10-min qualitative screening test for sulfamethazine (SM) in swine feeds is detailed. The method, which can be run in the field, uses 2 plastic tubes arranged piggyback style. The upper tube contains, from top to bottom, the feed sample (about 1 g), partially deactivated alumina, and an anion exchange resin buffered at pH 5.7. The bottom tube contains a small bed of anion exchanger buffered at pH 7.9, which traps the SM. After percolation of solvent through the system, the SM, if present, is eluted from the pH 7.9 resin and is reacted with Bratton-Marshall reagents to give a pink-to-lavender color. Feeds containing ≥0.15 ppm can be detected. A simple, additional dye concentration step allows for detection of 0.02 ppm, if desired. Only amphoteric primary aromatic amino-containing compounds with a pKa close to that of SM can theoretically interfere. Preparation of permanent color solutions using cobalt and copper acetates in glacial acetic acid is described for the optional establishment of the minimum concentration of SM in the feed. The method offers a simple way to detect some cross-contaminated withdrawal feeds containing >2 ppm SM, which can lead to violative (≥0.1 ppm) residues in swine liver.
Electrophoretic Method for Qualitative and Quantitative Analysis of Gelling and Thickening Agents
Authors: Pechanek U D O , Blaicher Gernot , Pfannhauser Werner , Woidich Herbert
Published: February 2020

An electrophoretic method has been developed for qualitative and quantitative determination of all common thickening and gelling agents. Thickeners were identified by their migration behavior, their staining ability, and the characteristic shapes of their electrophoretic zones, and then quantitated in a scanner. A method is also reported for isolating thickeners from food, including removal of fat and dyes by dioxane, enzymatic starch degradation, removal of protein by trichloroacetic acid, and precipitation of the polysaccharides by absolute ethanol. Isolation of gelatin is also described.
Reverse Phase High Performance Liquid Chromatographic Determination of Phenprocoumon in Tablets
Authors: Schmidt Walter F
Published: February 2020

A high performance liquid chromatographic procedure has been developed for the assay of phenprocoumon in tablets. In comparison to the present official USP assay procedure, it is equivalent in precision and accuracy and is faster and more specific. A mobile phase consisting of a 1% solution of acetic acid in acetonitrile-water (4 + 3) separates phenprocoumon from warfarin internal standard on a 6 μm octadecylsilane (ODS) column with UV detection at 311 nm. The method enables the concurrent determination of phenprocoumon and possible contaminants such as salicylic acid.
Workshop on the Determination of Lead in Foods by Graphite Furnace Atomic Absorption Spectrometry: Preliminary Report
Authors: Dabeka Robert W
Published: February 2020

Seven analysts with various degrees of trace element experience participated in a workshop on the determination of lead in foods containing 1-1000 ng lead/g. Each analyst independently performed 4 projects: contamination control, rapid screening for lead in canned milks, rapid determination of lead in foods, and solvent extraction determination of lead in foods. Accuracy and precision for all methods were good, and, using the solvent extraction method, analysts were able to accurately analyze milk containing 2 ng lead/g with a reproducibility standard deviation of 0.6 ng/g, including individual outliers, and 0.3 ng/g when outliers were rejected. Recovery at the 10 ng/g spiking level for milk averaged 107%. The results were exceptional considering that one of the analysts was a pesticide chemist, 5 other analysts spend only part of their time in trace element analysis, clean-room facilities were not used for any part of the study, the solvent extraction technique was preceded by a HNO3-HCIO4 digestion and was relatively complex, and the labware used for the entire workshop including digestions was either Pyrex or uncleaned, disposable polystyrene test tubes. The results of the workshop demonstrate that accurate, background-level lead determinations can be made inexpensively in normal laboratories, provided analysts are properly instructed in contamination control.
Reverse Phase Liquid Chromatographic Determination of Vitamins D2 and D3 in Milk
Authors: Muniz Juan F , Wehr C Timothy , Wehr H Michael
Published: February 2020

A single column reverse phase high pressure liquid chromatographic method is described for the determination of vitamins D2 and D3 in fluid milk. Resolution of vitamin D2 from D3 is helpful for use as an internal standard. The method involves overnight saponification at room temperature, extraction of unsaponifiables, precipitation of cholesterol, and aluminum oxide column cleanup. Sample extracts were chromatographed under isocratic conditions on a 10 μVydac reverse phase column using acetonitrile- methanol (90 + 10) as the mobile phase. In addition, a MicroPak MCH-5 reverse phase column with acetonitrile as the mobile phase was used with an automatic system for one product type. Thirty samples each of homogenized (3.8% fat), low fat (2.07c fat), and skim (≤0.5% fat) milk spiked with 200,400, and 600 IU vitamin D/qt were analyzed. Coefficient of variation (CV) and percent recovery for each product type and each spike level of vitamins D2 and D3 were calculated from 10 replicate analyses. Vitamin D2 recoveries for all product types at the 3 fortification levels varied from 85.2 to 99.7%; vitamin D3 recoveries varied from 85.9 to 98.8%. The minimum detectable quantity of vitamin D in milk was 15IU/qt.
Use of Post-Column Derivatization in Liquid Chromatographic Determination of Sulfamethazine and Sulfathiazole in Feeds and Feed Premixes
Authors: Stringham Rodger W , Mundell Elizabeth C , Smallidge Robert L
Published: February 2020

Sulfonamide drugs are extracted from feed and feed premixes by shaking with 0.15N HC1 in 25% methanol. The extract is diluted, clarified, and chromatographed on a reverse phase Cis column. Mobile phases used are methanol-2% acetic acid (35 + 65) and acetonitrile-2% acetic acid (18 + 82) for sulfamethazine (SMT) and sulfathiazole (STZ), respectively. A solution of dimethylaminobenzaldehyde (DMAB) is added to the column eluate and the resulting sulfonamide- DMAB complex is detected at 450 nm. The method was tested for linearity, recovery, and precision across a broad sample range. Recovery was 100.6 ± 2.3% and 96.3 ± 1.6% for STZ and SMT, respectively. Linearity was excellent (r2 = 0.9985 for STZ and r2 = 0.9996 for SMT) as was within-day precision (RSD = 2.00% for STZ and 1.52% for SMT). The method was compared with the Bratton-Marshall colorimetric method. Analysis of 14 STZ and 15 SMT samples failed to detect any bias between the 2 methods. Some practical aspects of the use of this technique are discussed.
Differential Pulse Polarographic Determination of N-Nitrosodiethanolamine in Cosmetic Products
Authors: Chou Hardy J , Yates Ronald L , Gajan Raymond J , Davis Henry M
Published: February 2020

A differential pulse polarographic (DPP) method is described for the detection and determination of JV-nitrosodiethanolamine (NDELA) in cosmetic products. The cosmetic sample is partitioned between IN HC1 and chloroform. The aqueous extract is isolated and further purified by passing it through a cartridge containing reverse phase high pressure liquid chromatographic (HPLC) packing (C18 Sep- Pak). Samples containing proteins are cleaned up by gel permeation chromatography. Direct polarographic interferences are removed by preparative HPLC. The prepared samples are then analyzed by polarography using the method of standard additions for quantitation. The DPP method can be used to determine NDELA in cosmetic products at levels as low as 100 ppb. Analyses of a commercial lotion and a commercial cream spiked at 3 levels in the ppm range gave recoveries ranging from 73 to 91%. The average of all recoveries was 80%.
Gas Chromatographic Method for Determining Strychnine Residues in Alfalfa
Authors: Miller Glenn , Warren John , Gohre Kirk , Hanks Larry
Published: February 2020

A gas-liquid chromatographic procedure is described for determining strychnine in alfalfa with a nitrogen- phosphorus detector. Alfalfa samples containing strychnine residues are chopped and extracted in a blender using ethyl acetate, sodium carbonate, and sodium sulfate, and the organic extract is extracted with 0.1N H2SO4 solution, made basic, and subsequently extracted with methylene chloride. Following concentration, the strychnine residues are quantitated by peak height, using an external standard. Recoveries for 0.05 ppm spikes were 88 ± 11%.
Levels of Lead in the United States Food Supply
Authors: Jelinek Charles F
Published: February 2020

As a result of the Food and Drug Administration’s (FDA) concern about lead in the food supply, considerable data have been developed in recent years by FDA, other agencies, and industry on the levels of lead in foods. Data obtained on the lead content of milk, eggs, meat, fish, and shellfish indicate that the mean levels in these unprocessed foods varied from 0.02 to about 0.4 ppm, with the lowest level in milk. The major food processing source of lead in food is the lead-soldered can. FDA had assigned top priority to the reduction of lead in foods for infants because of their greater susceptibility to the toxic effects of this metal. The lead levels in foods for infants are now only 1/5 to 1/10 of what they were when FDA expressed its concern about lead to the manufacturers of canned infant formula, evaporated milk, canned infant juices, and glass-packed infant foods. FDA priority interest has now shifted to reduction of lead in adult canned foods, especially those eaten by young children. The mean levels in such foods have decreased from 0.35-0.40 ppm in 1974 to 0.20-0.25 ppm in 1980.
Certification of Lead Concentration in Standard Reference Materials by Isotope Dilution Mass Spectrometry
Authors: Barnes I Lynus , Murphy Thomas J , Michiels Eddy A I
Published: February 2020

In response to needs for analytical standards by researchers studying the exposure of humans to lead, a wide variety of environmental and “food” Standard Reference Materials have been prepared and certified for lead as well as for many other elements. Among the food types are SRM1571, Orchard Leaves, 45 ppm; SRM 1575, Pine Needles, 10.8 ppm; SRM 1573, Tomato Leaves, 6.3 ppm; SRM 1566, Oyster Tissue, 0.48 ppm; SRM 1577, Bovine Liver, 0.34 ppm; SRM 1568, Rice Flour, 0.045 ppm; and SRM 1567, Wheat Flour, 0.020 ppm. These materials, intended for use in calibrating instruments and methods, have been certified by a definitive method, isotope dilution mass spectrometry. The advantages and disadvantages of this technique are discussed and some suggestions for the use of its isotopic selectivity in the study of lead in the human environment are presented.
Determination of Lead and Cadmium in Foods by Anodic Stripping Voltammetry: I. Development of Method
Authors: Gajan Raymond J , Capar Stephen G , Subjoc Cheryl A , Sanders Marion
Published: February 2020

Food samples are dry ashed at 500 ± 50°C with a 10% aqueous K2SO4 solution used as an ashing aid. The ashed sample is dissolved in 50 mL 2% HNO3. Anodic stripping voltammetry is used to determine lead and cadmium in a mixture of the sample solution and an acetate electrolyte at pH 4.3 ± 0.3. The estimated quantitation limits, based on a 10 g food sample, are 0.005 ppm for cadmium and 0.010 ppm for lead.
Inhibition of Chlortetracycline Activity by Magnesium Ions
Authors: Chiang Tom
Published: February 2020

Up to 50% of the antimicrobial activity of chlortetracycline (CTC) can be inhibited by the presence of MgSC»4 in microbiological turbidimetric assays. From 50 to 200 mM MgS04 inhibited CTC activity, and the relationship between CTC inhibition and MgSC»4 concentration is linear. The possible mechanism of this inhibition and its potential implication are discussed.
Rapid Gas-Liquid Chromatographic Method for Determination of Sulfamethazine in Swine Feed
Authors: Munns Robert K , Roybal Jose E
Published: February 2020

A gas-liquid chromatographic method is described for the quantitative determination of trace amounts of sulfamethazine in swine feed. Sulfamethazine is extracted in ammoniated acetone and isolated from other extractants on a Sephadex LH-20 column. The eluate is methylated with diazomethane and evaporated to dryness. The residue is dissolved in a solvent containing an internal standard of methyl sulfasymazine before being injected onto an OV-25 GLC column. An estimation of precision was established by assaying 10 sets of swine feed fortified with 0.5, 1,2, and 5 ppm SMZ. Mean recoveries were 96.0,94.3, 93.5, and 94.0%, respectively, with an average coefficient of variation of 3.07%. The critical steps and ruggedness of the method were also determined.
Extraction Procedures for Oilseeds and Related High Fat-Low Moisture Products
Authors: Sawyer Leon D
Published: February 2020

A combined sample preparation/extraction procedure is presented for pesticide residue analysis of oilseeds and related high fat-low moisture products. The procedure utilizes high-speed milling to prepare the sample and high-speed homogenization in the extraction step to achieve what is apparently quantitative isolation of both incurred residues and natural oils. A separate, simple, oil determination step allows findings to be reported on either the fat or whole product basis. Petroleum ether, ethyl etherpetroleum ether (1 + 1), and ethanol are used serially as the extractants. Usual fatty food cleanup procedures and multiresidue gas chromatographic detection techniques are utilized. The procedure presented in this paper is a refinement of earlier work which used a homogenizer both to grind and to extract samples of unground seeds and which demonstrated essentially complete extraction of endrin residues in soybeans and DDT residues in mustard seed. Identical samples analyzed by the currently recommended shakeout procedure, 29.012, gave recoveries of approximately 50% of the total residues. The procedure presented in this paper was satisfactorily tested on 13 different oilseed types and one sample of soda crackers. Oil content for these samples ranged from 5 to 69%.
Use of Iron Milk Medium for Enumeration of Clostridium perfringens
Authors: John William D St , Matches Jack R , Wekell Marleen M
Published: February 2020

A simple iron milk medium was used for isolation and enumeration of Clostridium perfringens from soil, sludge, and water samples. The whole milk contained only iron powder as a reducing agent; no other inhibitors were added. The iron milk most probable number (MPN) procedure was compared with 4 plating media: sulfite-polymyxin-sulfadiazine, Shahidi-Ferguson perfringens, tryptose-sulfite- cycloserine (both with and without egg yolk), and tryptone-sulfite-neomycin. The selectivity of the iron milk relies solely on the rapid growth of C. perfringens at 45°C and the stormy fermentation reaction within 18 h. Isolates were confirmed as C. perfringens by standard biochemical tests. The iron milk MPN procedure compared very well with the 4 plating media tested. Selectivity of incubation temperature, short incubation time, and ease of identification by the characteristic stormy fermentation make this method ideal for enumerating C. perfringens from large numbers of samples.