bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Analytical Methods Used to Determine
Metal Concentrations in Environmental Water Samples
Authors: Davis Andy , Olsen Roger
Published: February 2020

Al, Cd, Cu, Fe, Pb, Mn, and Zn were determined in water samples collected from Clear Creek and North Clear Creek, CO, that had been impacted by acid mine drainage. These samples contained a wide range of total suspended solid concentrations. The samples were prepared and digested by dissolved, acid-soluble, total recoverable, U.S. Environmental Protection Agency (EPA total), and Contract Laboratory Program (CLP) total procedures. The CLP method resulted in the highest reported metal concentrations for 67% of the analyses (primarily Al, Cd, Cu, and Fe), the EPA total method for 11 % of the analyses (mainly Mn and Zn), and the acid-soluble method for 9% of the analyses. For the remainder (13%), 2 or more methods resulted in similar metal concentrations. The same analyses using the Three Kids Mine standard reference material demonstrated that the EPA total and total recoverable methods underestimate the maximum metal concentrations in sediment-bearing water samples. In addition, use of acid-soluble or total methods is inappropriate to determine compliance with aquatic water quality standards that were originally promulgated on the basis of dissolved concentrations
Extraction of Light Filth from Oriental Sauces Containing Soy Sauce, Thickeners, and Spices: Collaborative Study
Authors: Nakashima Marvin J ,   Collaborators:, Gallman J A , Haynos R R , Highfield C E , Kelly G P , Loechelt H K , Millward P A , Ocus W , Rodriguez A , Wirth M D
Published: February 2020

Results are reported for a collaborative study of a method for the extraction of light filth from oriental sauces containing soy sauce, thickeners, and spices. A100 g test portion is pretreated in a 2% solution of Tergitol Anionic 4 over a steam bath, and oils are removed by wet-sieving on No. 230 sieve. Filth is isolated from 40% isopropanol by using Na4EDTA and mineral oil. Average recoveries by 9 collaborators for 3 spike levels of rat hairs (5,10, and 15) were 84, 78, and 79%, respectively; for insect fragments (5,15, and 30), recoveries were 92, 95, and 96%, respectively. The method was adopted first action by AOAC International.
Enzymatic Determination of Sulfite in Foods: NMKL Interlaboratory Study
Authors: Edberg Ulla ,   Collaborators:, Anttonen Maija-Liisa , Berg-Nilsen Karen , Blomberg Karin , Gjerstad Karl Olav , Gustavsson Tomas , Joner Per , Loimaranta Jukka , Mustranta Antti , Oksanen Mikko , Pero Leena , Sönsterud Björn
Published: February 2020

An enzymatic method for the determination of sulfite in foods was collaboratively studied in Nordic industry and government laboratories. The sulfite in liquid foods or extracts of solid foods is analyzed according to the following principle: Sulfite ions are oxidized to sulfate ions by oxygen in the presence of sulfite oxidase, thereby forming hydrogen peroxide. Hydrogen peroxide is transformed to water by reduced nicotinamide adenine dinucleotide (NADH) in the presence of NADH peroxidase. In this reaction, NAD+ is formed (and NADH is consumed) in amounts proportional to the sulfite concentration. Consumption of NADH can be measured spectro photo metrically at 340 nm. The method was collaboratively tested in 2 separate studies with high and low levels of sulfite tested. Results of both studies are reported here. The study samples consisted of potato flakes, wine, juice, and dried apples containing between 0 and about 960 mg SCVkg. Eleven laboratories participated in the full study and analyzed 12 samples. Six laboratories analyzed 8 samples in the complementary study. Before statistical evaluation of the collaborative study data, results were adjusted for the time-dependent decrease of sulfite in the case of materials with high sulfite content (dried apples and wine). For 2 blind duplicate samples of wine containing 75 mg S02/kg, the relative standard deviation for repeatability (RSDR, within-laboratory variation) was 3.9%. Relative standard deviation for reproducibility (RSDR, between-laboratory variation) was 7.6%. For 2 samples of dried apples containing 800 and 960 mg S02/kg, an RSDr value of 13.3% and an RSDR value of 13.9% were calculated. The corresponding parameters for 2 juice samples containing about 270 mg S02/kg were 4.8 and 10.4% for repeatability and reproducibility, respectively.
Matrix Solid-Phase Dispersion Extraction and Gas Chromatographic Screening of 14 Chlorinated Pesticides in Oysters (Crassostrea virginica)
Authors: Lott Heidi M , Barker Steven
Published: February 2020

A multiresidue isolation technique known as matrix solid-phase dispersion (MSPD) is presented for the extraction and subsequent gas chromatographic/electron capture detection (GC/ECD) determination of 14 chlorinated pesticides (α-BHC, (β-BHC, lindane, heptachlor, aldrin, heptachlor epoxide, p,p’-DDE, dieldrin, endrin, 4,4’-DDD, endrin aldehyde, p,p’-DDT, endosulfan sulfate, and methoxychlor) from oysters (Crassostrea virginica). Pureed whole oysters (0.5 g aliquots) are fortified with the 14 pesticides and δ-BHC, as an internal standard, and blended with 2 g C18 (octadecylsilyl)-derivatized silica. Pesticides are eluted from an extraction column composed of C18/oyster matrix blend and 2 g activated Florisil by addition of 8 mL acetonitrile-methanol (90 + 10). Then, 2 μL of the eluate is analyzed by GC/ECD. Unfortified blank controls are treated similarly. The eluate contained all the pesticide analytes and was free of interfering coextractants. Correlation coefficients for the standard curves of the 14 extracted pesticides (linear regression analysis) ranged from 0.9849 to 0.9980. Average relative percent recoveries over the range of concentrations examined (66 ± 12.7% to 84 ± 25.3%, n = 25 for each pesticide), interassay variability (13.6 ± 8.8% to 30.2 ± 9.1 %, n = 25 for each pesticide), and intra-assay variability (5.8-11.8%, n = 5 for each pesticide) indicated that the MSPD methodology successfully extracted and determined the 14 chlorinated pesticides in oyster at levels of 31.3-500 ng/g.
Determination of Oxyfluorfen in Pesticide Formulations by Liquid Chromatography
Authors: Bushway Rodney J , Perkins Lewis B
Published: February 2020

A normal-phase liquid chromatographic method was developed to determine oxyfluorfen, a herbicide, in pesticide formulations. Technical and liquid formulations were dissolved in 10% water and 90% tetrahydrofuran. A 5 μL aliquot was injected into a Phenomenex Spherex amino column and monitored at 240 nm. The mobile phase was tetrahydrofuran-hexane (5 + 95). Total analysis time was 80 min. Six different liquid formulations and 1 solid formulation were analyzed. Within-day percent coefficients of variation (%CVs) ranged from 0.5 to 3.5, and between-day %CVs ranged from 1.4 to 3.9. Purity of each oxyfluorfen chromatographic peak was checked by using a photodiode array detector in the spectrum mode. No interferences were observed.
Determination of Cymiazole Residues in Honey by Liquid Chromatography
Authors: Cabras Paolo , Melis Marinella , Spanedda Lorenzo
Published: February 2020

A liquid chromatographic method is described for the determination of cymiazole residues in honey. This acaricide is determined on a reversed-phase (C18) column, with a CH3CN-O.OOIN HCI-NaCI mixture (950 mL + 50 mL + 0.3 g/L) as the mobile phase, and UV detection at 265 nm. Cymiazole is extracted with n-hexane from aqueous alkalinized (pH 9) honey solutions. No further cleanup of the honey extract was required before chromatographic analysis. Recoveries on control samples fortified with 0.01,0.10, and 1.00 ppm cymiazole ranged from 92 to 102%. The limit of determination was 0.01 ppm.
Liquid Chromatographic Determination of 2-Chloro-4-nitroaniline, 2-Naphthol, and 2,4-Dinitroaniline in D&C Red No. 36
Authors: Scher Alan L , Adamo Nicholas C
Published: February 2020

A method is described for the determination of the intermediates and a related impurity in D&C Red No. 36 by reversed-phase liquid chromatography. This method may be used to ensure that limits set forth in the Code of Federal Regulations on the amounts of these 3 impurities in the color are not exceeded. The pigment is dissolved in boiling dioxane and then precipitated. The filtrate is chromatographed by isocratic elution, and then the column is washed and reequilibrated. Impurities were identified as 2-chloro-4-nitroaniline (2-CI-4-NA), 2-naphthol, and 2,4-dinitroaniline (2,4-DNA) by comparison of their retention times and spectra with those of standards. Peak area calibrations were linear to at least 0.375% 2-CI-4-NA, 1.25% 2-naphthol, and 0.025% 2,4-DNA, all with zero intercepts. At the specification levels, 99% confidence limits were 0.30 ± 0.006% for 2-CI-4-NA, 1.0 ± 0.03% for 2-naphthol, and 0.020 ± 0.0004% for 2,4-DNA. The limits of determination calculated from calibration data were 0.019% for 2-CI-4-NA, 0.10% for 2-naphthol, and 0.0014% for 2,4-DNA at the 99% confidence level. Recoveries were 100-104% for 2-CI-4-NA added to purified D&C Red No. 36,100% for 2-naphthol, and 100-110% for 2,4-DNA; relative standard deviations were 0.8-3.4%. A survey of certified D&C Red No. 36 samples showed that the batches contained higher levels of intermediates than were determined previously by a cellulose column method in which the pigment was not dissolved.
Determination of Residual Ethylene Oxide in Spectinomycin Hydrochloride Bulk Drug by Dynamic Headspace Gas Chromatography
Authors: Ramstad Tore , Miller Lisa S , Thomas Virginia N
Published: February 2020

A dynamic headspace gas chromatographic method was developed for the determination of residual ethylene oxide (EtO) in a pharmaceutical bulk drug, spectinomycin hydrochloride. The recommended column is PoraPLOT Q; PoraPLOT U was demonstrated to be equivalent. A detection limit of 2 ppb was achieved, and linearity was established to the highest value tested (5 ppm). The detection limit was 2-3 orders of magnitude lower than that achieved in previously published methods for EtO in pharmaceutical bulk drugs. Precision studies yielded relative standard deviations ranging from 2 to 10% over the 10-575 ppb concentration range. The method was applied to support EtO sterilization studies conducted at The Upjohn Company and was implemented for routine use. The sterilization studies demonstrated that residual levels of EtO <10 ppb are achievable.
Assay of Oxytetracycline Residues in Salmon Muscle by Liquid Chromatography with Ultraviolet Detection
Authors: Carignan Germain , Carrier Karen , Sved Stephen
Published: February 2020

A novel method for the assay of oxytetracycline residues in salmon muscle is described. Tissue is homogenized with 4 volumes of 1 % metaphosphoric acid in the presence of a small amount of dichloromethane (0.4 volume), shaken, and centrifuged. The residue is washed twice (4 and 2 volumes, respectively) with 1 % metaphosphoric acid, and the combined aqueous supernatants are concentrated to about 2 mL by flash evaporation and then diluted to 5 mL. Filtered aliquots of the extract are subjected to liquid chromatography using a C18 column with a mobile phase of acetonitrile-tetrahydrofuran- 0.025M aqueous oxalic acid (9 + 1 + 30) containing octanesulfonic acid at a final concentration of 10mM. Eluted peaks are monitored at 355 nm. Calibration and standard curves were linear from 0.01 to 0.5 μg on-column, with a limit of quantitation better than 0.05 μg/g. Recoveries from spiked blanks varied from 85.8 to 90.3% (relative standard deviation, 13.1-2.4%) in the 0.05-1.00 μg/g concentration range and were 21.1% at 0.02 μg/g.
Evaluation of Microbial Loads of Bacillus subtilis Spores on Penicylinders
Authors: Danielson James W
Published: February 2020

Three types of penicylinders were compared for their retention of spores of Bacillus subtilis testing for sporicidal activity of disinfectants. Glass, porcelain, and stainless steel penicylinders are inoculated with a water suspension of B. subtilis var. niger (ATCC 9372) spores and dried. One set of each type of penicylinder is submerged 1 h in 0.9% saline. One set of porcelain penicylinders is submerged 15 h in a neutralized chemical germicide, and one set is also inoculated with a culture filtrate of B. subtilis (ATCC 19659), dried according to the AOAC method, and submerged 1 h in 0.9% saline. Microbial loads simulate those held on carriers used to test sporicidal activity of disinfectants. Carriers are immersed in chemical germicide, transferred to a neutralizer, and placed in a culture medium. Average percentages of B. subtilis var. niger spores retained on 10 carriers after 1 h submersion in saline and in water were as follows: glass, 93.6%; porcelain, 99.9%; and stainless steel, 99.5%. Retention of spores after 15 h submersion in a neutralized chemical germicide and in water was 98.9%. Porcelain penicylinders inoculated from a culture filtrate of B. subtilis (ATCC 19659) retained 26% of the spores after being submerged 1 h in saline and placed in water. Glass penicylinders, which retained the lowest and most variable number of spores, were the least suitable for sporicidal activity testing. B. subtilis (ATCC 19659) spores tested on porcelain penicylinders met only the minimum HCI resistance requirements of ≥2 min. On porcelain penicylinders, the resistance of B. subtilis var. niger spores to 2.5N HCI was relative to the number of spores inoculated.
Reliability of Mycotoxin Assays — An Update
Authors: Horwitz William , Albert Richard , Nesheim Stanley
Published: February 2020

The precision parameters of the method-performance (collaborative) studies for mycotoxins published in the literature through 1991 have been recalculated on a uniform basis by following the International Union of Pure and Applied Chemistry protocol. About 80% of the 793 accepted assays for mycotoxins, almost all of which have been conducted by thin-layer chromatography (TLC), liquid chromatography (LC), and enzyme-linked immunosorbent assays (ELISA), exhibit relative standard deviations among laboratories (RSDR) that are less than 2 times the values predicted from the Horwitz equation:

RSDR,% = 2(1 - 0.5log10C)

where C is the concentration expressed as a decimal fraction. The precision of TLC and LC methods is about the same, but that of ELISA is somewhat poorer. For those commodities for which sufficient data exist to provide a meaningful comparison, the methods applied to cottonseed products have the best precision and corn the worst, with peanuts intermediate. Overall, however, the primary factor affecting RSDR is concentration, more or less independent of analyte, method, matrix, and age of the study. If it is assumed that the test results are normally distributed and that an RSDR of 50% is the point where effective control of the results begins to be lost (a value equivalent to the production of 2% false-negative values), then relying on the Horwitz curve, the limit of quantitative measurement is the single digit, i.e., 5,µg/kg (10-9; ppb) concentration for solid food commodities. Such a value must be considered as a limit applicable to a single analyte, aflatoxin B1, and not as a mean, and not applicable to the sum of the individual components, each of whose associated standard deviation would lie in the unacceptable region. Enforcement of a 5 µg aflatoxin B1/kg limit, under the assumptions made, requires that a responsible manufacturer and a prudent regulator operate at opposite extremes of tolerance limits: e.g., the producer at 2 µg/kg and the consumer at 10. A proposed Codex “maximum level” of 0.05 µg aflatoxin M1/kg milk cannot be supported by the available data applied in an interlaboratory enforcement environment. These conclusions are also supported by an examination of the reported data from the ongoing, large-scale proficiency studies routinely performed by the American Oil Chemists’ Society and the International Agency for Research on Cancer.
Solid-Phase Extraction and Liquid Chromatographic Determination of Monophthalates and Phthalide ExtractedFrom Solution Administration Sets
Authors: Snell Robert P
Published: February 2020

A liquid chromatographic procedure is described for the determination of phthalide, monobutyl phthalate, and mono-2-ethylhexyl phthalate leached by water from solution administration sets. Recoveries varied from 88.8% for phthalide at 1 (μg/50 mL to 113% for monobutyl phthalate at 6 μg/50 mL. Relative standard deviations at 1 μg/50 mL were 2.59% for phthalide, 3.54% for monobutyl phthalate, and 11.6% for mono-2- ethylhexyl phthalate. At 6 μg/50 mL, the relative standard deviation for mono-2-ethylhexyl phthalate decreased to 3.88%. Reproducibilities for 5 standard injections were 1.40% for phthalide, 1.84% for monobutyl phthalate, and 1.95% for mono-2- ethylhexyl phthalate. Correlation coefficients were 1.00 for the 3 compounds. Five sets from 2 manufacturers were examined. No phthalide or monobutyl phthalate was found. One manufacturer’s sets contained 37.6-44.4 μg/L mono-2- ethylhexyl phthalate. The sample matrix had some interference if phthalide or monobutyl phthalate was present.
Liquid Chromatographic Determination of Biogenic Amines in Dry Sausages
Authors: Eerola Susanna , Hinkkanen Riitta , Lindfors Erja , Hirvi Timo
Published: February 2020

National Veterinary Institute, Department of Chemistry, SF-00101, Helsinki, Finland A liquid chromatographic method is described for the determination of biogenic amines found in dry sausages: tryptamine, phenylethylamine, putrescine, cadaverine, histamine, serotonin, tyramine, spermidine, and spermine. Amines were extracted with perchloric acid solution and derivatized with dansyl chloride. After derivatization, ammonia was added to remove an interfering peak near cadaverine. Liquid chromatographic separations were performed by using a Spherisorb ODS2 column and an ammonium acetate-acetonitrile gradient elution program. The limits of determination of the individual amines were 1-5 mg/kg. This method is also applicable to detection of amines in other food samples.
Reporting Ongoing Results of Interlaboratory Comparison Programs
Authors: Viggers Elizabeth A , Atkinson June , Purcell Steve
Published: February 2020

International standards have been established for reporting individual ring trials, but no established general method has been developed! for reporting ongoing Interlaboratory Comparison Programs (ILCPs) to participants, although some attempts have been made to address the problem. The present paper describes a system that has been developed, tested, and used in New Zealand and which has improvements over many current schemes. It is consistent with international standards and meets the needs of laboratory analysts and managers. It emphasizes graphic output, and essential statistics are given but not emphasized. Feedback is produced within a week of the analysts’ reporting deadline. The system is based on principles agreed to among analysts, the statistician, the systems analyst, and the scheme manager, and it embraces a wide variety of chemical and microbiological tests. The present paper covers only the statistical and reporting aspects of the system.
Gas Chromatographic Determination of Benalaxyl Residues in Different Crops and Water
Authors: Crisippi Teodoro , Zini Guido , Fabbrini Riccardo
Published: February 2020

A gas chromatographic method is described that is suitable for the determination of benalaxyl residues ranging from 10 to 0.1 μg/kg in several crops, must, wine, and water. The compound is extracted with acetone and purified either by partitioning between water and n-hexane or by passing the extract through an Extrelut column with n-hexane. Further purification is achieved by column chromatography on alumina. The active ingredient is finally determined by gas chromatography with nitrogenphosphorus detection. Mean recoveries were ≥95% in the various crops tested and in the 0.01-1.05 mg/kg fortification range. Standard deviations for each crop were ≤6.5%.
Potential Application of LASER/Microbe Bioassay Technology for Determining Water-Soluble Vitamins in Foods
Authors: Anderson Ellen M , Angyal Gerald N , Weaver Carol M , Felkner I Cecil , Wolf Wayne R , Worthy Brenda E
Published: February 2020

A microbiological technique was developed for quantitating niacin by determining microbial growth rates in response to the amount of vitamin available. Unlike the current official AOAC method, the new procedure for niacin measured the growth rates during the early exponential growth phase rather than during the stationary phase. Lactobacillus plantarum was used to determine niacin to a lower limit of 100 pg/mL. The assay time was approximately 6 h, compared with 16-24 h for the current AOAC method. The extent of microbial growth was determined by differential light scattering of a LASER beam. Multiple photodetectors were integrated with a computer system to collect and analyze the data. The use of differential light scattering to determine 8 water-soluble vitamins under stationary phase conditions demonstrated the potential application of the new technology for microorganisms and foods.
Liquid Chromatographic Method for Determination of Iodine in Milk: Collaborative Study
Authors: Sertl David , Malone William ,   Collaborators:, Beljaars P , Blake C , Byerly C , Chadha R K , Daniels T , Duda C , Liu J , McShane B , Parns N , Pollman R , Ponto K , Sertl D , Soloman B , Stemp A , Vaessen H
Published: February 2020

Nine laboratories participated in an AOAC International/ International Dairy Federation collaborative study on a liquid chromatographic (LC) method for determination of iodine in milk. Liquid milk is passed through a 25 000 MW membrane filter to remove protein and insoluble material. Iodine (in the form of iodide) in the clear filtrate is separated by reversed-phase ion-pair LC and is detected electrochemically. Participants analyzed 2 commercial pasteurized whole milks and 5 nonfat dry milk powders in blind duplicate. Each sample was tested in duplicate on 2 days. Repeatability and reproducibility standard deviations (sr and SR, respectively) and repeatability and reproducibility relative standard deviations (RSDr and RSDR, respectively) for determinations of iodine in whole milk (mean recovery, 86.7%) were as follows: sr, 22 μg/L; SR, 22 μg/L; RSDr, 8.2%; and RSDR, 8.3%. For powdered milk (mean recovery, 91 %), the values were as follows: sr, 0.14 μg/g; SR, 0.22 μg/g; RSDr, 9.0%; and RSDR, 12.7%. The method was adopted first action by AOAC International.
Liquid Chromatographic Method for Determination of Sulfamethazine Residues in Milk: Collaborative Study
Authors: Weber John D , Smedley Michael D ,   Collaborators:, Bradley B , Carignan G , McGary E D , Rowe W D , Schenck F J , Thompson R D , Thorpe C W
Published: February 2020

Seven laboratories participated in a collaborative study of a liquid chromatographic (LC) method for determination of sulfamethazine (SMZ) residues in raw milk that were previously frozen. The milk is extracted with chloroform, the chloroform is evaporated, and the residue is suspended in hexane and extracted with 0.1 M KH2P04 (PDP) solution. The PDP extract is analyzed by LC on a C18 column with methanol–0.1M PDP (30 + 70) as mobile phase. Individual laboratories were instructed to analyze 5 replicates each of control milk, fortified control milk at 2 levels, and 3 blind samples. Blind samples included raw milk fortified with SMZ at 10 and 20 ppb and 1 sample containing SMZ residue from a dosed cow. For blind fortified samples containing 10 ppb SMZ, average recovery and relative standard deviations for repeatability and reproducibility (RSDr and RSRR) based on the results from 6 of the 7 participating laboratories were 8.21 ppb, 7.16%, and 23.16%, respectively. Similar data, including results from a seventh participant who reported instrumental problems but was not eliminated by the Dixon outlier test, were 9.13 ppb, 8.38%, and 31.94%, respectively. These results demonstrate that the method is suitable for the determination of SMZ residues in milk at 10 ppb and above. The method was adopted first action by AOAC International.
Rapid Determination of Supplemental Vitamin E Acetate in Feed Premixes by Capillary Gas Chromatography
Authors: Kmostak Svatomir , Kurtz David A
Published: February 2020

A rapid capillary gas chromatographic method was developed for determination of supplemental cc-tocopherol acetate (containing and verified at 50–5000 mg/kg feed) in various kinds of feed premixes. The method is based on simple n-hexane extraction of feed samples pretreated with a solution of acetic acid in ether for matrix breakdown followed by column cleanup on deactivated alumina to eliminate background interference. Fused silica chromatography is completed in 3 min. The withinday precision expressed as the relative standard deviation for recovery examples was 3.4,2.9, and 4.0% for high, medium, and low concentrated feed premixes, respectively; extraction recovery was 99–110%. The storage stabilities of standards and feed premix preparations were found to be excellent up to 3 months and up to 60° C.
Liquid Chromatographic Method for the Determination of Nine Phenolic Antioxidants in Butter Oil: Collaborative Study
Authors: Denis Page B ,   Collaborators:, Carl M , Daniels D , Dominguez F , Essers M L , Hollman P C H , Rico I Ibanez , Ito Y , Kaiser R , Kempf U , Kittle C , Lacroix G , Lombaert G , Miyata M , Pettipas R , Pocifia R , Willis C , Wong L
Published: February 2020

Ten laboratories collaboratively studied a liquid chromatographic (LC) method for the determination of propyl, octyl, and dodecyl gallate (PG, OG, and DG, respectively), 2,4,5-trihydroxybutyrophenone (THBP), ferf-butylhydroquinone (TBHQ), nordihydroguaiaretic acid (NDGA), 2- and 3-tert-butyl-4- hydroxyanisole (BHA), 2,6-di-ferf-butyl-4-hydroxymethylphenol (lonox-100), and 3,5-di-terf-butyl-4- hydroxytoluene (BHT) in butter oil. The 10 samples analyzed were spiked in matched pairs at about 100,50, and 10 μg/g. In the method studied, antioxidants are extracted as in AOAC LC method 983.15, but different LC eluants are used to separate the 9 antioxidants. Results from 1 laboratory were rejected as not valid and were not included in any calculations. For the remaining 9 laboratories, the overall mean recoveries for PG, THBP, TBHQ, NDGA, BHA, OG, lonox, BHT, and DG were 100.9, 97.8,103.4,95.4, 97.4,93.6,95.5,79.0, and 96.2%, respectively. The overall reproducibility relative standard deviations were 8.55,17.4,25.6,14.5,6.60, 9.64,10.8,11.4, and 7.35%, respectively. The method was adopted first action by AOAC International as a modification of AOAC method 983.15.
Comparison of Kjeldahl Method for Determination of Crude Protein in Cereal Grains and Oilseeds with Generic Combustion Method: Collaborative Study
Authors: Bicsak Ronald C ,   Collaborators:, Boles R , Cathey R , Collins V , Hannasious K , Haselhorst J , Henderson L , Jann L , Meschi L , Molloy R , Stillions M , Swanson K , Tate D , Webb J , Wilkins G
Published: February 2020

Seven laboratories participated in a collaborative study to extend the applicability of the AOAC generic combustion method for determination of crude protein in animal feed (990.03) to include determination in cereal grains and oilseeds. In the study, method 990.03 was compared with the AOAC mercury catalyst Kjeldahl method for determination of protein in grains (979.09) and crude protein in animal feed (954.01). The study also evaluated the effect on the results of fineness of grind. For determination of crude protein in grains and oilseeds by the combustion method, standard deviations for repeatability and reproducibility ranged from 0.10 to 0.37 and from 0.25 to 0.54, respectively, and relative standard deviations for repeatability and reproducibility ranged from 0.77 to 2.57% and from 1.24 to 3.15%, respectively. The combustion method was adopted first action by AOAC International for determination of crude protein in cereal grains and oilseeds containing 0.2- 20% nitrogen.
Total Bacterial Count in Raw Milk Using the BactoScan 8000
Authors: Rodrίguez-Otero J L , Hermtoa M , Cepeda A , Franco C
Published: February 2020

The BactoScan 8000 (Foss Electric) automatically performs a total count of bacteria in raw milk. It was designed for fast, repeatable counting. The apparatus counts the individual bacteria (IBC) instead of colony forming units (CFU). IBC provides more information on the state of milk hygiene than the CFU count. The repeatability, sr, was 0.033 log (IBC/μL), which is equivalent to a coefficient of variation of 7.9% (IBC/μL). The carryover, which is the contamination one sample imposes on the next, was 0.19%. The BactoScan 8000 was calibrated against the reference method of counting colonies on a Petri dish. The correlation coefficient for 429 milk samples was r= 0.88, and the standard deviation of the residuals, syx, was 0.259. The detection limit was 15 CFU/μL. We recommend establishing a system of payment to farmers based on the bacteriological quality of their milk as determined by the BactoScan 8000. Because results are obtained in IBC/μL, analytical differences resulting from conversion to CFU/|iL are eliminated.
Evaluation and Application of a Bioluminescent Bacterial Genotoxicity Test
Authors: Sun Thomas S C , Stahr Henry M
Published: February 2020

The Mutatox® test (commercial name for the bioluminescent bacterial genotoxicity test) has been shown to be a good alternative to the Ames test. The test uses dark mutants of luminous bacteria (Vibrio fischeri) and determines the ability of various genotoxic agents to restore the luminescence by inducing mutation. It provides a rapid screening test which can be used to assay the genotoxicity of large numbers of pure and complex compounds. The test is completed in 1 day, and by serially diluting the compound, dose response data plus toxicity data can be generated for a number of samples simultaneously. For the direct assay (without exogenous metabolic activation), the positive controls selected were 3,6-diaminoacridine (proflavine) and N-methyl-N-nitro-nitrosoguanidine. For the S-9 assay, which incorporated the microsome fraction (S-9) from rat liver as an exogenous metabolic activation system, the positive controls selected were aflatoxin B1 and benzo(a)pyrene. This study also indicated that methyl-imidazo-quinoline and tryptophan pyrolysates were genotoxic in the presence of S-9 activation, aflatoxin B1 epoxide and fumonisin B1 showed direct genotoxic activity, and aflatoxin B2 and ochratoxin A were not genotoxic.
Determination of Selenium in Feeds, Premixes, Supplements, and Injectable Solutions by Hydride-Generated Inductively Coupled Plasma Atomic Emission Spectrometry
Authors: Anderson Kim A , Isaacs Brandon
Published: February 2020

A simple method is described for the determination of 0.01-30 000 μg selenium/g sample. Selenium is present in feed supplements, premixes, mineral mixes, and injectable solution as either selenite or selenate. High concentrations of other common minerals present in these supplements are tolerated by the method. The samples are initially digested by heating with nitric acid and then boiled in a mixture of sulfuric and perchloric acids to convert all selenium species to selenate. The selenate is reduced to selenite, Se (IV), with hydrochloric acid at 95°C. The selenite in turn is then reduced by acidic sodium borohydride to hydrogen selenide, which is measured by hydride-generated inductively coupled plasma atomic emission spectrometry at 196.026 nm. The instrument detection limit for this method is 0.0005 μg Se/g sample.
Citrate Insoluble P2O5: Problems with Ammoniated Fertilizers
Authors: Gliksman Joseph E
Published: February 2020

An AOAC collaborative study of a new direct method for available P2O5 in fertilizer was conducted last year. Results on a monoammonium phosphate sample showed more variability than other sample types, and the sample also had the largest absolute difference among 3 methods (960.02,960.03, and a new direct method). Problems with the AOAC method for citrate insoluble P2O5 were discovered, and an editorial change in the method is recommended.
Analysis of Milk-Based Infant Formula. Phase IV. Iodide, Linoleic Acid, and Vitamins D and K: U.S. Food and Drug Administration-Infant Formula Council: Collaborative Study
Authors: Tanner James T , Barnett Stephen A , Mountford Mardi K ,   Collaborators:, Barnett S , Beare-Rogers J L , Bueno M P , DeAngelis N , deVries E J , DeVries J W , Dube D , Ellefson W , Landen W O , Navis J , Pearson D , Reynolds S L , Richards P , Soliman A-G , Thomson W
Published: February 2020

In 1982, the U.S. Food and Drug Administration, the Infant Formula Council and its member companies, contract laboratories, and other government laboratories began a study of analytical methods for the nutrients listed in the Infant Formula Act of 1980. Phases I, II, III, and V have been completed. The present report provides data on Phase IV, in which 13 laboratories collaboratively studied an ion-selective electrode method for analyzing iodide, a gas chromatographic method for linoleic acid, and 2 liquid chromatographic (LC) methods each for vitamins D and K. Data were insufficient to evaluate one each of the LC methods studied for vitamins K and D. The relative standard deviations (RSD) are sufficient for the nutrient levels found in infant formula. RSDs (%) for repeatability (RSDr) and reproducibility (RSDR), respectively, were as follows: iodide, 4.0-11.4 and 13.5-18.2; linoleic acid, 1.0-1.6 and 3.5-5.1; vitamin K1, 3.2-16.0 and 6.2-19.4; and vitamin D3,4.2 and 35.0. The recommendation to adopt the method for vitamin D was supported by the results of a ministudy. All laboratories were capable of using these methods with little training. The methods for determination of iodide, linoleic acid, and vitamins D and K in ready-to-feed milkbased infant formula have been adopted first action by AOAC International.
Enzymatic Method for Determination of (1→3)(1→4)-Beta-D-glucans in Grains and Cereals: Collaborative Study
Authors: Zygmunt Lucian C , Paisley Steven D ,   Collaborators:, Bromley G , Durany G , Ellis C , Elrefaie J , Fein R , Lewis S , Lee S , Marlett J , Peterson D , Prodolliet J , Tassin D , Weisz J , White P , Xia L
Published: February 2020

The McCleary enzymatic assay for mixed linkage (1→3)(1→4)-beta-D-glucans has been modified to apply to oat and barley fractions and ready-to-eat (RTE) cereals. The proposed method involves lower sample concentrations; stirring the samples; a longer, warmer lichenase digestion; and longer beta-glucosidase digestion. These changes result in higher recovery of beta-glucan. This modification expands on the American Association of Cereal Chemists (AACC) Method 32-22 by the addition of a desugaring procedure, which is necessary for RTE cereals. Results from collaborative studies sponsored by AACC and AOAC demonstrate good precision for an enzymatic assay. The average relative standard deviation for reproducibility (RSDR, a measure of inter laboratory variation) for 20 oat, barley, and cereal samples was 9.7%. The average RSD for repeatability (RSDr, intralaboratory variation) was 5.0%. The enzymatic method has been adopted first action by AOAC International for determination of beta-glucans in oat and barley fractions, and ready-to-eat cereals.
Determination of 2-Ethyl-l-Hexanol as Contaminant in Drinking Water
Authors: Vitali M , Leoni V , Chiavarini S , Cremisini C
Published: February 2020

An analytical procedure for the determination of 2-ethyl-1-hexanol (2-EH) in drinking water is presented. The method is based on volatile-compound stripping, adsorption on activated-charcoal-filled tubes, solvent elution, identification by gas chromatography/ mass spectrometry, and determination by gas chromatography with flame ionization detection. Bottled samples with undesirable organoleptic characteristics were analzyed to determine a possible correlation with the presence of 2-EH. The presence of 2-EH at 2-10 μg/L was confirmed in several samples. The presence of di-2-ethylhexyl phthalate (D2EHP) was also checked in all samples. This compound was always found at 2-30 μg/L. Hydrolysis of D2EHP was carried out for 2 weeks to evaluate its possible contribution to water contamination by 2-EH. Tests did not show measurable amounts of the alcohol. Nonetheless, the hydrolysis of phthalates in the weakly acidic conditions of the examined waters would not justify the presence of 2-EH at the observed levels, and so it is reasonable to hypothesize a direct contamination from packaging materials containing 2-EH as residue from D2EHP synthesis.
The Need for Larger Analytical Samples with Granulated Feed Additives
Authors: Coleman Mark R , Wicker Alan L , Moran John W
Published: February 2020

Sampling an animal feed containing a granulated analyte is extremely difficult. A granulated feed additive, Tylan® (Elanco, tylosin), was used to demonstrate how a granulated product can increase assay variability if steps are not taken to reduce and control this variability. The number of tylosin granules was determined for Granulated Tylosin Concentrate, the active ingredient of Tylan Premix. Multiple weighings of 3 lots of the concentrate were prepared, and the average number of granules per gram of concentrate was determined with the aid of image analyses. The total weight of Tylan Premix in varying analytical samples was calculated. Finally, the average number of tylosin granules per analytical sample was calculated based on the average number of granules per gram. A10 g analytical sample obtained from an animal ration containing 8 ppm tylosin activity would contain an average of 1.16 granules of tylosin, and a 100 g analytical sample would contain 11.6 granules. These calculations demonstrate the need to increase the analytical sample size in analyzing an animal feed containing a granulated feed additive.
Liquid Chromatographic Determination of Six Sulfonamide Residues in Animal Tissues Using Postcolumn Derivatization
Authors: Bui Lap V
Published: February 2020

A sensitive and reproducible liquid chromatographic method is described for the simultaneous determination of sulfonamide residues in animal livers and kidneys. The selectivity of the method is enhanced significantly through the use of postcolumn reaction with p-dimethylaminobenzaldehyde, followed by detection at 450 nm. Consequently, the cleanup is simplified; it consists of removal of fatty material by partitioning the sample extract into an acetonitrile-hexane system. The sulfonamides used for this study were sulfadiazine, sulfapyridine, sulfamerazine, sulfadimidine, sulfamethoxypyridazine, and sulfaquinoxaline. At the level of 100 μg/kg, the recoveries ranged from 70 to 104% and were dependent on the nature of the matrix and the particular sulfonamide. The coefficients of variation are 2-10% at this level. The detection limit was 20 μg/dg.
Confirmatory Method for Sulfonamide Residues in Animal Tissues by Gas Chromatography and Pulsed Positive Ion-Negative Ion-Chemical Ionization Mass Spectrometry
Authors: Mooser Andrê E , Koch Herbert
Published: February 2020

A confirmatory method has been developed for determination of 13 sulfonamides in edible tissues. The assay involves extraction from a solution resulting from a screening procedure by liquid chromatography and subsequent derivatization. Sulfachloropyridazine (SCP), sulfadiazine (SDA), sulfadimethoxine (SDM), sulfamethazine (SMZ), sulfamerazine (SME), sulfamethoxazole (SMX), sulfamethoxypyridazine (SMP), sulfapyridine (SPR), sulfaquinoxaline (SQX), and sulfathiazole (STA) were detected as the N1-methyl-N4-trifluoroacetyl derivatives, sulfaguanidine (SGU) as the same derivative after cyclization by hexafluoroacetylacetone, and sulfacetamide (SAC) as the methyl derivative. These sulfonamides were detected by gas chromatography and pulsed positive ion-negative ion-chemical ionization mass spectrometry with methane as the reactant gas, whereas sulfanilamide (SAA) was determined as the methyl derivative by electron-impact ionization.
Cuprimetric Assay of Casein Hydrolysates
Authors: Silvestre M P C , Lati E , Dauphin C , Hamon M
Published: February 2020

A simple, reproducible, and precise potentiometric assay (copper indicator electrode) has been developed for alkalinized solutions of pure casein hydrolysates, with or without additional amino acids, carbohydrates, or lipids (short chain tryglicerides; SCT) using a titrated copper (II) sulfate solution. The copper consumption is related to both free amino acid and peptide contents. Thus, in comparison with the (α-amino nitrogen determination, the method described here gives better information about the composition of protein hydrolysates.
A Quantitative Linearity Evaluation Method for Infrared Milk Analyzers
Authors: Smith Erika B , Barbano David M , Lynch Joanna M , Fleming J Richard
Published: February 2020

Nonlinearity in the uncorrected signal for any channel of the infrared milk analyzer can cause decreased accuracy of the final corrected result. A procedure quantifying the amount of residual nonlinearity in the uncorrected signal for each channel was developed for use in the range of milk component concentrations appropriate for producer payment testing. For the fat channels, a homogenized 6% fat milk is diluted with water to obtain a series of solutions from 0 to 6% fat. For the protein and lactose channels, evaporated skim milk is diluted with water to obtain linearity solutions from 2.8 to 3.9% true protein and 4.3 to 6.0% anhydrous lactose. The selection of dilution method (i.e., weight/weight or volume/volume) should be based on how the final calibrated instrument values are to be expressed (i.e., weight/weight or weight/volume). A non-zero forcing linear regression is conducted within a chemical range by using known component concentrations as the dependent variable (Y) and uncorrected infrared signals as the independent variable (X). Residual nonlinearity values are calculated. A channel possesses unacceptable nonlinearity if residual values are ≥±0.02% at any point within the component range normally encountered in producer payment testing. The linearity status of 18 instruments was determined.
Use of Standard Additions to Diagnose Matrix Effects in the Atomic Absorption Spectrophotometric Analysis of Feed Blended for a Roxarsone Combination Study
Authors: Webster Gregory K , Hearne Loretta A
Published: February 2020

Roxarsone (3-nitro-4-hydroxyphenylarsonic acid) is a feed additive commonly used in the poultry industry. Its use is approved at levels ranging from 0.0025 to 0.005% in feed. This additive is routinely assayed in industry by AOAC Official Methods 971.47 (Roxarsone In Feeds and Premixes: Spectrophotometric Method) and 986.39 (Roxarsone in Feeds: Atomic Absorption Spectrophotometric Method). The atomic absorption spectrophotometric method is quite advantageous, because it is accurate and efficient. Occasionally, analysis of feeds by this method yields questionable results. This communication details the investigation of such an occurrence and the application of standard additions to detect this problem in future analyses.
Evaluation of Trace Elements in Wheat and Wheat By-Products
Authors: Ahmad Shujaat , Waheed Shahtoa , Mannan Abdul , Fatema Ismat , Qureshi Iqbal Hussain
Published: February 2020

Wheat and wheat by-products from Pakistan were analyzed to study the concentrations of 21 essential or toxic elements. Neutron activation analysis in combination with atomic absorption spectroscopy were used to determine the concentrations of Al, As, Br, Cd, Cl, Co, Cr, Cs, Cu, Fe, Hg, K, Mn, Na, Ni, Pb, Rb, Sb, Sc, Se, and Zn. Our results were compared to results reported from other countries. The weekly human intakes of toxic trace elements from wheat flour samples collected in Pakistan were estimated. These calculations were then compared to the World Health Organization’s suggested weekly tolerance levels of each element. Also, global distribution patterns for certain of these trace elements in wheat flour were discovered.
Gas Chromatographic/Mass Spectrometric Identification of a Pyridinedicarboxylic Acid Impurity in Niacin as the Trimethylsilyl Ester
Authors: Kirchhoefer Ross D
Published: February 2020

A pyridinedicarboxylic acid impurity in bulk niacin was identified by derivatization and comparison with reference materials by using gas chromatogra-phy/mass spectrometry. The niacin bulk material was dissolved in pyridine and derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) reagent. The resulting trimethylsilyl (TMS) esters of niacin and its associated impurities were chromatographed on a cross-linked methyl silicone capillary column with temperature programming. Derivatization and injection of the 6 pyridinedicarboxylic acid geometric isomers showed that 3 of the dicar-boxylic acids, 2,3- (also known as quinolinic acid), 2,5-, and 2,6-pyridinedicarboxylic acid, all rearrange to give a component with a mass spectrum identical to that of the impurity. The other 3 isomers, 2,4-, 3,4-, and 3,5-pyridinecarboxylic acid, do not rearrange, and therefore, cannot be the impurity detected in the niacin bulk material. The amount of pyridinedicarboxylic acid impurity in the bulk niacin is less than 0.02%.
Levels and Incidences of Pesticide Residues in Selected Agricultural Food Commodities Available in Canada
Authors: Neidert Eli , Trotman Raymond B , Saschenbrecker Peter W
Published: February 2020

During the 32 month period ending December 31, 1991, Agriculture Canada analyzed 13 230 samples of agricultural food commodities for pesticide residues. Both domestic and imported commodities were tested. A multiresidue method that can detect over 200 analytes was routinely used. Results in violation of Canadian tolerances were discerned in 224 samples. An additional 2501 samples contained at least one pesticide residue at a detectable but nonviolative level. Violations most often result from pesticide–commodity combinations for which there is no established specific tolerance.
Sporicidal Activity of Chemical Germicides on Bacillus subtilis Spores Under Various Conditions
Authors: Danielson James W , Peeler James T , Oxborrow Gordon S
Published: February 2020

Sporicidal tests were conducted on chemical germicides used for reprocessing hemodialyzers. The germicides that were tested for sporicidal activity contain some of the same active ingredients as many other commercial germicides, although instructions for dilution and exposure time may vary according to intended use. Cidex-Dialyzer™ (glu-taraldehyde), formaldehyde, Renalin™ (peracetic acid), and RenNew-D™ (chlorine dioxide) were each tested under the following conditions: at 50, 100, and 150% of the recommended concentration in soft water at 22°C; and at 1× the recommended concentration in soft water at 26.7°C, in hard water at 22°C, and in hard water containing 5% bovine serum at 22°C. Sporicidin-HD™ (glutaraldehyde–phenol) was tested only at the recommended concentration in soft water at 22°C. The time required for a 2-log reduction in the initial concentration of spores ranged from 1.8 min for Renalin at 150% of the recommended concentration to 26.4 h for formaldehyde in hard water containing 5% bovine serum. Cidex-Dialyzer at 50% of the recommended concentration and Sporicidin-HD at the recommended concentration were ineffective against Bacillus subtilis var. niger spores. The sporicidal activities of RenNew-D and formaldehyde were greatly reduced when bovine serum was added to hard water. Renalin had the highest sporicidal activity and was the least affected by each of the conditions tested.