bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid Chromatographic Determination of Sulfadiazine in Salmon by Postcolumn Derivatization and Fluorescence Detection
Authors: Gehring Theresa A , Rushing Larry G , Thompson Harold C
Published: February 2020

A reversed-phase (ODS-2) liquid chromatographic method was developed to determine low nanogramper-gram levels of sulfadiazine (SDZ) in salmon muscle tissue. SDZ was extracted with acetonitrile-aqueous 2% acetic acid (pH 3.0), partitioned into methylene chloride, and cleaned up by using a strong-cation-exchange, solid-phase extraction cartridge. SDZ was derivatized postcolumn with fluo-rescamine and detected by fluorescence. The limit of detection was 0.2 ng SDZ/g tissue. Recoveries from coho salmon tissue fortified with 1,5,10, and 20 ng SDZ/g tissue averaged 84.5,85.0,83.6, and 83.9%, respectively; recoveries from Atlantic salmon tissue fortified with 10 ng SDZ/g tissue averaged 82.6%.
Gas Chromatographic Determination of Yohimbine in Commercial Yohimbe Products
Authors: Betz Joseph M , White Kevin D , Marderosian Ara H Der
Published: February 2020

The bark of Pausinystalia yohimbe [K. Schumann] Pierre (Rubiaceae), long valued as an aphrodisiac in West Africa, recently has been promoted in the United States as a dietary supplement alternative to anabolic steroids for enhancement of athletic performance. As the number of yohimbe products on the retail market increases, concerns about their safety are raised because of the reported toxicity of yohimbine (the major alkaloid of the plant). Although plant materials are usually identified microscopically, we were unable to identify them in many of the products, because as their labels indicated, the products were mixtures of various bo-tanicals or were bark extracts and contained little or no plant material. A method for extraction and capillary gas chromatographic (GC) separation of the alkaloids of P. yohimbe was, therefore, developed and used to analyze a number of commercial yohimbe products. The method involved solvent extraction and partitioning in chloroform–water followed by separation on a methyl silicone capillary GC column (N–P detection). Comparisons of chromatograms of extracts of authentic bark with those of commercial products indicated that, although many products contained measurable quantities of the alkaloid yohimbine, they were largely devoid of the other alkaloids previously reported in this species. Concentrations of yohimbine in the commercial products ranged from <0.1 to 489 ppm, compared with 7089 ppm in the authentic material. Authentic bark has been reported to contain up to 6% total alkaloids, 10–15% of which are yohimbine. The possible presence of undeclared diluents in the products was indicated by peaks in product chromatograms but not in those of authentic bark.
Infrared Analysis of Milk: Effect of Homogenizer and Optical Filter Selection on Apparent Homogenization Efficiency and Repeatability
Authors: Smith Erka B , Barbano David M , Lynch Joanna M , Fleming J Richard
Published: February 2020

The apparent homogenization efficiency (AHE) and repeatability of one instrument was measured with 5 instrument homogenizers that differ in true homogenization efficiency (THE) to determine if instrument characteristics change when different fat A and B optical filters are used in the same machine. Inefficient homogenizers demonstrated both poor repeatability and poor AHE with both sets of fat B filters. One set of fat A filters produced infrared readings that were influenced less by differences in homogenization efficiencies than the other set. The most inefficient homogenizer demonstrated poor repeatability and failed AHE evaluation with both pairs of fat B filters and one pair of fat A filters. Differences in the transmission characteristics of the 2 sets of fat A filters influenced results of AHE evaluation for the most inefficient homogenizers. However, a very efficient homogenizer passed evaluation of AHE and demonstrated good repeatability on both unhomogenized and homogenized milks regardless of differences in the spectral characteristics of filters. A second objective was to determine if AHE test values are correlated with true differences in milk fat globule (MFG) size distribution. A good correlation was found between AHE and THE data for a group of homogenizers for one reference milk. A weakness of the AHE tesl is that the MFG size distribution of the externally homogenized reference milk may vary from one evaluation to another, resulting in an inconsistent reference point for AHE values. The preferred method of evaluating homogenization efficiency of infrared milk analyzers is analysis of the MFG size distribution resulting from instrument homogenization of unhomogenized milk.
Determination of Phenol Sulfone, Phenol Sulfoxide, and Phenol Sulfonic Acid Metabolites of Fenamiphos in Soil by Liquid Chromatography
Authors: Mattern Gregory C , Parker Gilbert D , Green Debra L , Yeutter Gregory L
Published: February 2020

An analytical method has been developed to quantitate fenamiphos phenol sulfone, phenol sulfoxide, and phenol sulfonic acid in soil. Both control and analyte-fortified soil samples from Fresno, CA, were extracted with methanol–water (2 + 1) and partitioned with ethyl acetate. Fenamiphos phenol sulfone and phenol sulfoxide were determined by re-versed-phase liquid chromatography (LC) with UV detection at 240 nm after cleanup by silica solid-phase extraction. Fenamiphos phenol sulfonic acid was determined by reversed-phase ion-pairing LC with UV detection at 240 nm after cleanup by amino solid-phase extraction. Recoveries of fenamiphos phenol sulfoxide ranged from 88.2 to 111.0%, with an average of 97.4%. Recoveries of fenamiphos phenol sulfone ranged from 101.6 to 107.0%, with an average of 104.6%. Recoveries of fenamiphos phenol sulfonic acid ranged from 76.0 to 99.9%, with an average of 86.0%. Responses for analysis of analytes in both solvent and soil matrix were linear over the tested range of 10 to 500 ppb. Limits of determination of each analyte in soil were less than 10 ppb.
Comparison of Recoveries of Selected Organochlorine Pesticides, Related Compounds, and Polychlormated Biphenyls 1254 and 1260 from Fat after Kuderna-Danish and TurboVap Concentration
Authors: McCarthy Helen T , Sullivan Anna R
Published: February 2020

A 2-part study was performed to compare tho Tur-boVap evaporator v/ith the traditional Kuderna-Darv-Ish concentrator for analysis of selected pesticides and related compounds (study 1) and polychlorinated biphenyls (PCBs) (study 2) In fat samples. To compare results, bias and precision data were evaluated for pesticides and related compounds and bias v/as evaluated for PCBs. For study 1, 20 samples of poultry fat were spiked with known amounts of 13 pesticides and related compounds. Samples were extracted v/ith petroleum ether, cleaned up with Florisil, and evaporated in either a Kudorna-Danlsh concentrator or a TurboVap evaporator. The pesticides and related compounds were identified and quantitated by gas chromatography v/ith electron capture detection. Biases, as indicated by average recoveries of pesticides and related compounds, were 63 and 73%, respectively, for the TurboVap and Kudema-Danlsh procedures. Recoveries of pesticides and related compounds, except methoxychlor, by tho TurboVap evaporator were significantly lower (p ≤ 0.05) than recoveries by Kudema-Danish concentration. Average recoveries with the TurboVap procedure were 10% lower than recoveries with the Kudema-Danlsh procedure. Precisions for both procedures were determined by testing for equality of variances with the F-test. A significant difference (p ≤ 0.05) for precision between the 2 procedures was found only for endrin. Study 2 was conducted on 14 accreditation PCB samples from the U.S. Department of Agriculture’s Food Safety and Inspection Service. PCB recoveries were 70–125% with the Kuderna-Danish apparatus and 69–106% with the TurboVap evaporator. No significant difference (p > 0.05) was found between the 2 procedures for PCB analysis. The TurboVap ovaporator gave consistently lower results for pesticides and related compounds compared with the traditional Kuderna-Danish concentrator; precisions for both procedures were similar. Results for PCBs analyzed by both procedures v/cre not significantly different. Lower recoveries for pcstlcidos and rotated compounds notwithstanding. tho TurboVap concentrator offers advantages over tho older Kudorna-Danlsh ovaporator In terms of turnaround time and efficient use of laboratory space.
Comparison of On-Column and Precolumn Derivatization for Liquid Chromatographic Determination of Molybdenum in Seawater and Bovine Liver
Authors: Nagaosa Yukio , Kobayashu Tetsuya
Published: February 2020

A rapid, accurate, and sensitive method was developed for the determination of molybdenum in seawater and bovine liver samples by reversed-phase liquid chromatography (LC) using a Cia column. The method was based on chelation of the metal with 8-hydroxyquinoline by on-column or precolumn derivatization followed by LC elution with acetonitrile-0.02M acetate buffer (3 + 2; pH 4.1) and 1 × 103M of the ligand as the mobile phase. The spectrophotometric detection was made at 390 nm. Data obtained from the 2 derivatizations (on- and precolumn chelation) were compared in terms of detection limit, precision, accuracy, and ease of LC determination of molybdenum. No significant difference exists in the detection limit and the sensitivity of the 2 methods. However, the on-column chelation method, that is, the direct injection of aqueous samples onto the column, showed relatively less interference from manganese and greater simplicity in operation compared with precolumn chelation; therefore, on-column chelation is preferable for routine analyses. The on-column method produced mean levels of 9.6 ± 0.4 μg/L for the seawater sample and 3.6 ± 0.2 μg/g (certified value, 3.5 ± 0.5 μg/g) for bovine liver.
Diarrhetic Shellfish Poisoning: Evaluation of Enzyme-Linked Immunosorbent Assay Methods for Determination of Dinophyslstoxin-2
Authors: Carmody Eoin P , James Kevin J , Kelly Seán S
Published: February 2020

Dinophysistoxin-2 (DTX-2), an isomer of okadaic acid (OA), recently has been found in Irish waters. DTX-2 was the predominant toxin during prolonged infestations in cultivated mussels along the southwest coast of Ireland. Substantial variations in toxin levels may exist both horizontally and vertically in the water column. The need to take multiple samples and the ethical concern about the use of mammals for routine quality control of shellfish prompted examination of 2 commercially available enzyme-linked immunosorbent assay (ELISA) methods, designed to detect OA, for determination of both OA and DTX-2. One ELISA method (DSPCheck, Sceti Co. Ltd., (Tokyo, Japan) showed good cross-reactivity (40 ± 5%) with standard DTX-2. This study showed that both ELISA methods show good correlation with the liquid chromatographic analysis of 9-anthryldiazomethane derivatives when OA is the predominant toxin present. The sensitivity was also good for OA determination using both methods, which allowed toxin measurement at 10 ng/mL (0.5 ng/well). This level is equivalent to 0.03 μg/g mussel meat. Blank mussel samples spiked with DTX-2 standards gave a good linear correlation (r = 0.997) with this ELISA method when toxin levels were 0.03-0.3 μg/g mussel meat. This range is appropriate for regulatory control of diarrhetic shellfish poisoning.
New Approach to Processing of Gas Chromatographic/Mass Spectrometric Data for Detection of Off Flavors in Complex Mixtures
Authors: Fay Laurent B , Staempfli Andreas A
Published: February 2020

Chemical compounds responsible for off flavors in foodstuffs are often difficult to identify because of their low levels in complex matrixes. A simple method is described to detect and identify off flavor compounds by gas chromatographic/mass spectrometric (GC/MS) analysis and data processing for sorting the GC/MS files in 14-ion series. The 14 homologous-ion series correspond to the sum of the intensities of the ions, x + (CH2)n, where x varies from 1 to 14 and n varies from 1 to ∞, allowing to cover the whole acquired mass range. Processing of the ion series allows automatic screening of all acquired masses. We use this method routinely in our laboratory to find compounds responsible for a contamination. It is a powerful tool for off flavor identification by comparison between a reference and a contaminated sample. The method can be used with any type of data system and any chromatographic instrument coupled to a mass spectrometer.
Incomplete Data Sets: Coping with Inadequate Databases
Authors: Albert Richard H , Horwttz William
Published: February 2020

Three problems arise in handling numerical values in databases: bad data, missing data, and sloppy data. The effects of bad data are mitigated by using statistical subterfuges such as robust statistics or outlier removal. Missing data are replaced by creating a substitute through interpolation or by using statistics appropriate to unbalanced designs. Sloppy, semiquantitative data are relegated to innocuous positions by using nonparametric, rank, or attribute statistics. These techniques are illustrated by the telephone directory, a database of carcinogenicity test results, and a database of precision parameters derived from method performance (collaborative) studies.
Monitoring of Pesticide Residues in Human Milk, Soil, Water, and Food Samples Collectedfrom Kafr El-Zayat Governorate
Authors: Dogheim Salwa M , Mohamed El-Zarka , Gad Alla Sohair A , El-Saied Samia , Salama Emel Y , Mohsen Ayoub M , Fahmy Safaa M
Published: February 2020

Pesticide residues in human milk and environmental samples from Kafr El-Zayat Governorate in Egypt were analyzed. This governorate is located near one of the biggest pesticide factories in Egypt. Organochlorine and organophosphorus pesticides were monitored, including those that have been prohibited from use in Egypt. Human milk samples (31 samples) from Kafr El-Zayat were compared with 11 samples collected from Cairo. Data were compared with results from studies performed in 1987 and 1990. The present study showed that aldrin and dieldrin, heptachlor and heptachlor epoxide, and endrin residues have been eliminated from human milk. Estimated daily intakes (EDIs) of DDT complex and γ-HCH by breast fed infants in Kafr El-Zayat were 85.96 and 3.1% of the respective acceptable daily intakes (ADIs). β- HCH residues showed an increasing pattern, especially in human milk samples from Cairo. DDT complex and HCH isomers in orange, spinach, lettuce, potatoes, and clover samples ranged from undetectable to very low concentrations. Higher levels of DDT and HCH were detected, but aldrin, dieldrin, endrin, and the heptachlors were not detected in food of animal origin. Residues in fish samples were below maximum residue limits established by some developed countries. Those in animal milk samples approached the extraneous residue limits of the Codex Committee on Pesticide Residues. HCH residues in soil were negligible, but DDT resi dues in soil were some what higher. Among watersamples, groundwater samples had the highest residues of HCHs and DDTs, followed by Nile River water and then tap water. However, the organo chlorine pesticide residues were found at concen trations below the maximum allowable limits set by the World Health Organization for drinking water. Among 12 organophosphorus pesticides moni toredas parent compounds, dimethoate,malathion, methamidophos, and chlorpyrifos residues were detected in low concentrations in soil samples from a pesticide factory. No organophosphorus pesticide residues were found in plant samples, except for very low residues of dimethoatein anorange sample. Water samples were devoid of organophosphorus residues as parent compounds.
Assay of Biogenic Amines Involved in Fish Decomposition
Authors: Malle Pierre , Vallé Michel , Bouquelet Stephane
Published: February 2020

A liquid chromatographic (LC) method is described for quantitative determination of putrefaction amines: putrescine, cadaverine, histamine, spermidine, and spermine. These amines are extracted from fish bygrinding with perchloric acid at -20°C. The amines are reacted with dansyl chloride at alkaline pH, dried under a stream of nitrogen, placed in an automatic injector at -20°C, and separated ina Kromasil C18 reversed-phase column at 25°C. A new gradient elutes the amines in 22 min and regenerates the column in 30 min. Regression lines are obtained with high coefficients of correlation. This method is faster and more reproducible than other methods and shows that the quality index is a reliable, albeit species-specific, criterion of fish decomposition.
Chlortetracycline, Oxytetracycline, and Tetracycline in Edible Animal Tissues, Liquid Chromatographic Method: Collaborative Study
Authors: MacNeil James D , Martz Valerie K , Korsrud Gary O , Salisbury Craig D C , Oka Hisao , Epstein Robert L , Barnes Charlie J ,   Collaborators:, Alfredsson G , Barry C , Bergner B , Chan W , Diserens J M , IInicki L P , Klein E , Koscinski B , Vasco G , Phillippo T , Mawhinny H , Mϋller E , Petz M , Oka H , Patel R , Telling G M , Webb M , Henry C , Farrington Wh H
Published: February 2020

Thirteen laboratories analyzed samples of edible animal tissues for tetracycline residues. The method included extraction of analytes into buffer, elution from a C18 solid-phase extraction (SPE) cartridge, and reversed-phase liquid chromatographic (LC) analysis, including use of a confirmation column. An additional laboratory, using an alternative LC assay based on a different sample cleanup, also analyzed the samples. Results showed the 2 methods are comparable. The LC method for determination of cholortetracycline, oxytetracycline, and tetracycline in edible animal tissues has been adopted by AOAC INTERNATIONAL. Results from 13 laboratories indicate that the method under study provides generally better results at the higher concentrations tested than at concentrations near the detection limit and that there is less problem with interferences in muscle tissue than in kidney. The method can achieve reliable results for analytes and matrixes studied at concentrations from 0.1 to 0.6 ppm and above, depending on the analyte-matrix combination, with generally better performance to be expected with muscle than with kidney. The poorer performance for fortified samples, particularly kidney, was attributed to additional homogenization steps required to prepare these samples. Recovery of analytes from different
Determination of Deoxynivalenol in Wheat, Barley, and Malt by Column Cleanup and Gas Chromatography with Electron Capture Detection
Authors: Tacke Beth K , Casper Howard H
Published: February 2020

A rapid and reliable method to determine deoxyni- valenol (DON) in wheat, barley, and malt is described. Samples are extracted with acetonitrile- water (84 + 16). Extracts are eluted through a C18- alumina (1 + 3) column, evaporated to dryness, and derivatized with trimethylsilylimidazole-trimethyl- chlorosilane (100 + 1). DON is identified and quantitated by capillary gas chromatography with electron capture detection. This method can quantitate DON levels from 0.2 to 40 ppm. Multiple analyses of wheat spiked at 2 ppm and of naturally contaminated wheat, malt, and barley resulted in coefficients of variation of 5.1, 5.1, 6.0, and 9.8%, respectively. Recoveries of DON spikes at 3 levels were 94-100% for wheat, 100-105% for barley, and 100105% for malt. Results for wheat sample analyzed with this procedure (1.9± 0.1 ppm DON) compared well with results for the same sample analyzed by enzyme-linked immunosorbent assay (1.9 ppm DON) and by liquid chromatography (1.7 ppm DON).
Pesticide Residue Concentrations in the Belgian Total Diet, 1991-1993
Authors: Dejonckheere Willy , Steurbaut Walter , Drieghe Sabine , Verstraeten Roland , Braeckman Hans
Published: February 2020

In the period 1991-1993, an official study was conducted to measure the presence and evaluate the risk of pesticide residues in plantbased food in the Belgian total diet. Positive samples were subjected to one or more culinary treatments (washing, peeling, steaming, or cooking) to determine the decrease of residues in prepared ready-to-eat food. Thus, better estimates of pesticide residues taken up through consumption were determined and compared with toxicological criteria. Washing did not significantly reduce residues. Peeling fruits removed almost all pesticides. The effects of cooking and steaming varied, depending on the type of food and pesticide.
Determination of Atrazine in Water by Magnetic Particle Immunoassay: Collaborative Study
Authors: Hayes Mary C , Jourdan Scott W , Herzog David P ,   Collaborators:, Barnes P , Charan C , Fleeker J , Francis H , Litke D W , Hall C , Luitweiler P , Lucas A , Marti L , Mihaliak C , Mumma R , Spittler T , Strauss J , Thurman E M
Published: February 2020

A collaborative study was performed to determine mean recovery and precision for analysis of atrazine in drinking and surface waters by immunoassay. The study design was based on the blind duplicate test plan for collaborative studies. Three blank waters (municipal drinking water, well water, and surface water) were spiked at 3 atrazine levels. Two water samples with naturally incurred atrazine loads were also spiked with atrazine at 3 levels. In the enzyme-linked immunoassay method, the water sample is mixed with a pesticide–enzyme conjugate and added to paramagnetic particles with triazine-specific antibodies attached. After separation of antibody-bound atrazine and atrazine–enzyme conjugate from free components, the bound enzyme conjugate catalyzes a reaction producing a colored end product. The color developed is inversely proportional to the original concentration of atrazine in the water sample. Fourteen laboratories participated in the collaborative study. Data were analyzed for repeatability and reproducibility, and average recoveries at the spike levels were calculated. Over the concentration range tested, the mean recovery of atrazine spiked into blank and pesticide-contaminated waters was 104%. Overall RSDRaveraged about 40% for atrazine concentrations near the method detection limit (0.05 μg/L) and about 15% at concentrations above 5 times the detection limit (0.25 μg/L). Corresponding single-analyst RSDr values were 24 and 10%. Recovery and precision for the 3 blank water matrixes and the waters that had been naturally contaminated with atrazine showed no significant differences. The magnetic particle immunoassay
Rapid Identification and Quantitation of Clotrimazole, Miconazole, and Ketokonazole in Pharmaceutical Creams and Ointments by Thin-Layer Chromatography–Densitometry
Authors: Roychowdhury Utpal , Das Saroj K
Published: February 2020

Thin-layer chromatography (TLC)–densitometry was used to separate, identify, and quantitate clotrimazole, miconazole, and ketokonazole (alone or combined with other drugs) in various pharmacopoeial or proprietary creams and ointments. Clotrimazole was extracted from the cream or ointment with ethyl alcohol, and miconazole and ketokonazole were extracted with a mixture of equal volumes of chloroform and isopropyl alcohol. Active ingredients were separated from excipients and other drugs by TLC on a precoated silica gel F254 plate with a solvent system of n-hexane–chloroform–methanol–diethylamine (50 + 40 + 10 + 1, v/v). The 3 azoles were well separated and easily identified in this chromatographic system. The separated azoles were visualized under short-wave UV light and quantitated by scanning densitometry at 220 nm by comparing the integrated areas of samples with those of standard (one azole was used as internal standard for the other). Recoveries from samples spiked with known amounts of azoles were excellent. The method was validated further by comparison with official liquid chromatographic methods.
Efficacy of a Latex Agglutination Test for Rapid Identification of Staphylococcus aureus: Collaborative Study
Authors: Chang Tsung C , Huang Su H ,   Collaborators:, Chao H Y , Chen B L , Chen C , Chen C H , Chen T R , Chin C Y , Chiu C P , Chiu F P , Chou J , Chyr C Y , Chu S Y , Hsiao S M , Hsieh Y M , Huang A , Huang W I , Hung S S , Ko H C , Lin L P , Lin P Y , Liu C B , Liu F C , Sheu Y I , Shie J S , Tai T F , Tsai S J , Wang S J , Wen S C , Wong H C , Yan L P , Yeh T
Published: February 2020

Fifteen laboratories completed a collaborative study comparing the efficacy of a latex agglutination kit (Aureus Test) with that of AOAC Official Method 987.09 (coagulase test for identification of Staphylococcus aureus). Each laboratory analyzed 240 strains of bacteria, including 160 isolates of S. aureus and 80 isolates of other bacteria. Upon receipt of cultures, collaborators subcultured each isolate on both tryptic soy agar (TSA) and Baird-Parker agar medium (BPA) to determine whether the growth medium has any effect on either method. For cultures grown on TSA, the latex test had sensitivity and specificity rates of 99.2 and 97.1 %, respectively, whereas the coagulase test had respective rates of 98.4 and 92.5%. For cultures able to grow on BPA, the latex test had sensitivity and specificity rates of 99.2 and 96.6%, respectively, while the coagulase test had respective rates of 98.3 and 91.3%. By using the McNemar pairwise comparison test of the 2 methods, the falsepositive and false-negative rates of the latex test were significantly lower (p < 0.01) than those of the coagulase test for strains grown either on TSA or BPA. The latex agglutination test for identification of S. aureus isolated from foods has been adopted by AOAC INTERNATIONAL.
Liquid Chromatographic Determination of Free Glutamic Acid in Soup, Meat Product, and Chinese Food: Interlaboratory Study
Authors: Beljaars Paul R , Van Dijk Remmelt , Bisschop Eric , Spiegelenberg Willem M ,   Collaborators:, Hofman I , Houwen I , de Jeu C , Klerx W N M , Knaake H H A , Koopmans H , van der Linden W , Radstake D , Sens J , Steendam L , Vernoon H , van der Weert R
Published: February 2020

An interlaboratory study of the liquid chromatographic (LC) determination of free glutamic acid in soup, meat product, and Chinese food was performed. Homogenized food samples were extracted with hot water, filtered, and diluted. Aliquot portions were treated with N,N-dimethyl-2-mer-capto-ethyl-ammonium chloride (DMMAC) and o phtaldialdehyde (OPA) to convert glutamic acid to a stable fluorescent complex. After LC separation on a reversed-phase C18 column with acetonitrile–phosphate buffer (pH 7.O)–water (80 +180 + 740, v/v) as mobile phase, glutamic acid peaks were measured fluorometrically (excitation, 340 nm, and emission, 389 and/or 440 nm). Homocysteic acid was used as internal standard. Twelve samples (6 blind duplicates) containing about 0.3–1.3% (w/w) of glutamic acid were analyzed singly by 12 laboratories. Results from one participant were excluded. Repeatability relative standard deviations (RSDr) varied from 1.3 to 4.5%, and reproducibility relative standard deviations (RSDR) ranged from 4.1 to 7.1 %. Average recovery of glutamic acid determined at 6 levels was 101.5% (range, 98–106%).
Rapid Method Based on ATP Catabolites for Evaluating the Freshness of Baltic Herring: Interlaboratory Study
Authors: Hattula M Tapani , Wallin Harriet C
Published: February 2020

An interlaboratory study was performed in 31 Finnish laboratories to determine the quality of Baltic herring (Clupea harengus membras). Three fish samples representing 3 levels of freshness were analyzed. To evaluate chemical freshness, a rapid paper strip method based on the degradation products of ATP was used by 22 participants. Eleven laboratories used liquid chromatography. Each laboratory also classified the samples by sensory evaluation. The rapid paper strip method proved to be a satisfactory screening method for assessing freshness of Baltic herring.
Liquid Chromatographic Method for Determining Capsaicinoids in Capsicums and Their Extractives: Collaborative Study
Authors: Parrish Mark ,   Collaborators:, Berard K , Cooper T , Das R , Esseltine C , Gonzalez L , Greenwood R , Grenon I , Humphries J , Hurst L , Korpinski T , Lucius D , Potter J , Schonfeld R , Soh E , Stengel F , Woody M
Published: February 2020

Sixteen laboratories participated in an AOAC–American Spice Trade Association (ASTA) collaborative study of a liquid chromatographic (LC) method for determining capsaicinoids in capsicums and their extractives. Capsicums are extracted with ethanol by refluxing and then filtered. Capsaicinoids in the filtrate are separated by re- versed-phase LC and detected spectrophotometri� cally with external standard quantitation. Participants analyzed 6 ground capsicum and 3 oleoresin products as 12 samples from a mixed scheme of blind duplicates and Youden matched pairs. Average repeatability and reproducibility standard deviations (sr and sR, respectively) and average relative standard deviations (RSDr and RSDR, respectively) for ground red pepper were as follows: sr, 610 Scoville heat units (SHU); sR, 1730 SHU; RSDr, 1.7%; RSDR, 4.9%. For ground chili peppers, the values were sr, 60 SHU; sR, 160 SHU; RSDr, 4.0%; RSDR, 10.6%. For oleoresin red pepper, the averages were sr, 46820 SHU; sR, 54990 SHU; RSDr, 8.5%; RSDR, 11.2%. The LC method has been adopted first action by AOAC INTERNATIONAL.
Speciation and Determination of Dissolved Iodide and Iodine in Environmental Aqueous Samples by Inductively Coupled Plasma Atomic Emission Spectrometry
Authors: Anderson Kim A , Casey Barbara , Diaz Elmer , Markowski Peter , Wright Brent
Published: February 2020

Total dissolved iodide (I−) and iodine (I2) are determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) using iodine vapor generation. I− is determined directly after filtration. It is oxidized in situ to I2 with potassium nitrite in sulfuric acid in a simplified continuous-flow manifold. A standard nebulizer separates I2, which is quantitated by ICP-AES at 206.16 nm. The instrument detection limit for I− is 0.04 μg/mL. Recoveries from seawater, saltwater, and freshwater standard reference materials ranged from 86.5 to 118.6%, averaging 98.2%. I2 is analyzed by ICP-AES without the iodine vapor generation reagents. For samples containing both I2 and I−, total iodine is determined with oxidizing reagents, I2 alone is determined without oxidizing reagents, and I− is calculated from the difference. The analysis is specific for the 2 species (I− and I2). Stability of I2 in environmental samples was briefly investigated. This method demonstrates good accuracy and precision for samples of environmental interest and is especially well suited to small samples. It requires no additional apparatus for iodine generation or sample introduction.
Molecular Detection of Clostridium botulinum Type E Neurotoxin Gene in Smoked Fish by Polymerase Chain Reaction and Capillary Electrophoresis
Authors: Sciacchttano Carl J , Hlrshfield Irvin N
Published: February 2020

The polymerase chain reaction (PCR), a rapid, sensitive technique for amplifying target DNA sequences of pathogenic microorgansims, was used to amplify Clostridium botulinum type E neurotoxin gene fragments in smoked fish. Other botulinal neurotoxin-producing strains, nontoxigenic strains, and food-related microorganisms did not yield nonspecificamplification products with this PCR assay. PCR products were analyzed by capillary electrophoresis (CE) using a low-viscosity entangled polymer system. Resolution, sensitivity, and DNA sizing accuracy were improved, and analytical times were markedly shortened. The PCR/CE assay detected the C. botulinum type E neurotoxin gene in as few as 10 cells. The technique to other foods may also be a valuable tool for detecting foodborne pathogens.
Mycotoxins Transmitted into Beer from Contaminated Grains During Brewing
Authors: Scott Peter M
Published: February 2020

Studies with aflatoxin B1, ochratoxin A, zearalenone, deoxynivalenol, and fumonisins B1 and B2 added at various stages of the brewing process show that these mycotoxins (or metabolites) may be transmitted from contaminated grains into beer. Citrinin does not survive the mashing step. Mycotoxins in beer could originate from the malted grain or from adjuncts. Although high incidences and concentrations of aflatoxins and zearalenone have been found in local beers brewed in Africa, aflatoxins have not been detected in European beers. Zearalenone and α- or β-zearalenol (the metabolite likely to occur) have not been found in Canadian and European beers, except for one sample analyzed by thin-layer chromatography only. Ochratoxin A rarely has been detected at >1 ng/mL in beer; liquid chromatographic methods with a 0.05-0.1 ng/mL detection limit, however, have shown moderately high incidences of trace levels. Deoxynivalenol, which survives the brewing process, has been found with high incidence in Canadian and European beers, with concentrations of >200 ng/mL reported in several German beers. Fumonisins B1 and B2 occur to a limited extent in beer.
Modular Methodology for Determination of Poly chlorinated Biphenyls in Soil as Aroclors and Individual Congeners
Authors: Donnelly Joseph R , Grange Andrew H , Herron Nelson R , Nichol Gregory R , Jeter Jeffrey L , White Richard J , Brumley William C , Van Emon Jeanette
Published: February 2020

A comprehensive screening and confirmatory method was developed for monitoring polychlorinated biphenyls (PCBs), both as Aroclors and as individual congeners. This approach incorporates extraction, extract cleanup, and analysis modules designed to match cost, time, and data quality requirements. Soxhlet, sonication, supercritical fluid, and accelerated solvent extractions were evaluated. Carbon chromatographic cleanup procedures were used for separation of congeners on the basis of ortho substitutions, which permitted calculation of toxicity equivalents. Individual congener determinations, congener total histograms, and peak comparison techniques for Aroclor identification were elaborated by using high and low resolution mass spectrometricdata. A screening procedure based on immunoassay using the Ohmicron PCB RaPID AssayTM kit gave results comparable to those obtained by gas chromatography with electron capture detection in the range 0.40-230 ppm, when the appropriate Aroclor calibrator was used.
Determination and Confirmation of Pirlimycin Residue in Bovine Milk and Liver by Liquid Chromatography/Thermospray Mass Spectrometry: Interlaboratory Study
Authors: Heller David N ,   Participants:, Matusik Jean
Published: February 2020

Three laboratories participated in trials of methods to determine and confirm pirlimycin residue in bovine milk and liver. The methods used liquid chromatography/ thermospray mass spectrometry (LC/MS) with an internal standard to measure residue concentration. The internal standard was isopirlimycin, a stereoisomer of pirlimycin, which was resolved chromatographically. Determinative procedures were validated by replicate analyses of negative control, fortified control, and residue-incurred milk. For the milk method, average corrected recoveries (and coefficients of variation, CVs) were 83- 113% (CV, 7.5-15.4%) at 0.2 ppm, 91-98% (CV, 3.4- 18.5%) at 0.4 ppm, and 89-102% (CV, 8.8-22.9%) at 0.8 ppm. For the liver method, average corrected recoveries were 94-103% (CV, 2.2-7.1%) at 0.25 ppm, 87-94% (CV, 4.8-10.3%) at 0.5 ppm, and 96-101% (CV, 5.5-6.9%) at 1.0 ppm. There were no interferences in control samples of either matrix. Pirlimycin was confirmed by matching the retention time and relative abundances of 4 ions from sample extracts to corresponding values obtained for pirlimycin standard. Pirlimycin was confirmed in all residue- incurred samples and all samples fortified at regulatory tolerances (0.4 ppm in milk and 0.5 ppm in liver) by 2 of the 3 laboratories and in most samples by the third laboratory
Nondestructive Determination of Lead, Cadmium, Tin, Antimony, and Barium in Ceramic Glazes by Radioisotope X-Ray Fluorescence Spectrometry
Authors: Anderson David L , Cunningham William C
Published: February 2020

Quantitation capabilities of radioisotope X-ray fluorescence spectrometry (RXRFS) for determining lead, cadmium, tin, antimony, and barium in ceramic glazes were investigated. Twenty-one airdried glazes and 85 fired glazes on test tiles were analyzed by using 109Cd and 57Co excitation sources. Accurate Pb determinations, with limits of detection (LODs) of about 0.3 mg/cm2 for 5 min counting times, were achieved by using the 75 keV Kα1 X-ray photopeak and a Pb foil calibration procedure. Cd, Sn, Sb, and Ba concentrations were determined with LODs from about 0.5 to 1.5 mg/cm2. For Pb and Ba, results obtained by using absorption corrections based only on element concentrations determined by RXRFS and an iterative approach led to analytical biases of ≤4% relative to results obtained by using corrections based on known total element compositions. Biases were more severe for Cd, Sn, and Sb because lower X-ray energies were involved and sensitivities varied as a function of matrix Pb content. Pb concentrations were above LODs (1.3-40 mg/cm2) in 39 of 47 fired "foodsafe" glazes and in 33 of the other 38 fired glazes (0.4-39 mg/cm2).
Determination of Selenium in Infant Formula and Enteral Formula by Dry Ash Graphite Furnace Atomic Absorption Spectrometry with Deuterium Background Correction
Authors: Cook Kathleen K
Published: February 2020

A method was developed to determine selenium in infant formula using a graphite furnace equipped with deuterium background correction after dry ashing. The method circumvents the use of perchloric acid, 2,3-diaminonapthalene (DAN) and hydride generation without the use of Zeeman background correction. Twelve commercial infant and enteral formulas and corresponding spiked products (30-500 ng) were analyzed in triplicate for Se to evaluate this method. All test portions were digested on a hot plate after addition of magnesium nitrate-nitric acid. Following heating, digests were evaporated to dryness and placed in a 500°C muffle furnace for 30 min to complete ashing. All Se was converted to Se+4 by dissolving the ash in HCI (5 + 1) and holding the solution for 20 min in a 60°C water bath. Se+4 was subsequently reduced to Se0 with ascorbic acid and collected on a membrane filter. The membrane filters were digested in a small volume of nitric acid in a microwave oven. Following digestion, contents of the vessels were diluted and analyzed for Se by graphite furnace atomic absorption spectrometry. Selenium standards in starch or in unfortified formula containing trace levels of Se were carried through the entire process. The recovery range for Se was 85-127%, and analyzed reference materials fell within their certified range for Se. This method is as sensitive (detection limit 0.44 ng Se/g) as methods reported in the literature and may be applicable to other foods.
Gas Chromatographic Determination of Butylated Hydroxyanisole (BHA) and Butylated Hydroxytoluene (BHT) in Products Containing Capsaicinoids
Authors: DeWitt Bernard , Finne Gunnar
Published: February 2020

Because of interference by coeluting capsaicinoids, the commonly used liquid chromatographic method for determining butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) in pepperoni and spice blends is not reliable. A gas chromatographic method is described that cleanly separates these antioxidants from interfering substances. Average recoveries of BHA and BHT from oleoresin spiked at 5 concentrations were 97.6 and 104.3%, respectively. From pepperoni spiked at 4 levels, average recoveries were 79.1 and 87.9%, respectively. The repeatability of the method when applied to 5 replicates of pepperoni toppings was 36.4 ± 1.1 ppm for BHA and 32.2 ± 0.8 ppm for BHT.
Liquid Chromatographic Determination of Oxytetracychne in Swine Tissues
Authors: Kawata Shigeru , Sato Kazuhiko , Nishikawa Yuusuke , Iwama Kjmio
Published: February 2020

A simple and rapid method was developed for determination of oxytetracycline (OTC) in swine muscle and kidney by liquid chromatography (LC). The method involved homogenization of sample in acetonitrile–1M imidazole buffer containing 10 mM disodium ethylenediaminetetraacetic acid (Na2 EDTA) and 50 mM magnesium acetate (15 + 85) with added hexane, centrifugation, removal of the hexane phase, and ultrafiltration of the supernatant. L-column ODS (150 × 4.6 mm) with a mobile phase of acetonitrile–1M imidazole buffer containing 50 mM magnesium acetate and 10 mM Na2 EDTA (10 + 90) was used for the LC separation. A fluorescence detector was used at an excitation wavelength of 380 nm and an emission wavelength of 520 nm. The calibration graph was linear from 1.25 to 200 ng OTC. Recoveries of OTC from swine tissue fortified at levels of 0.05–1.0 μg/g ranged from 58.0 to 67.3%. The quantitation and detection limits were 0.05 and 0.04 μg/g, respectively.
Rapid Determination of Ampicillin in Bovine Milk by Liquid Chromatography with Fluorescence Detection
Authors: Ang Catharina Y W , Wenhong Luo
Published: February 2020

A rapid and sensitive liquid chromatographic (LC) method was developed for the determination of am- picillin residues in raw bovine milk, processed skim milk, and pasteurized, homogenized whole milk with vitamin D. Milk samples were deprote- inized with trichloroacetic acid (TCA) and acetonitrile. After centrifugation, the clear supernatant was reacted with formaldehyde and TCA under heat. The major fluorescent derivative of ampicillin was then determined by reversed-phase LC with fluorescence detection. Average recoveries of ampicillin fortified at 5,10, and 20 ppb (ng/mL) were all >85% with coefficients of variation <10%. Limits of detection ranged from 0.31 to 0.51 ppb and limits of quantitation, from 0.66 to 1.2 ppb. After appropriate validation, this method should be suitable for rapid analysis of milk for ampicillin residues at the tolerance level of 10 ppb.
Effect of Lipid Extraction Methods on Total Dietary Fiber and Nonstarch Polysaccharide Contents of Selected Nuts and Seeds
Authors: Li Betty W , Zhao Zhenkun , Jekot Jill J
Published: February 2020

Three extraction methods were used to remove lipid materials from 8 edible nuts and seeds before analysis for their total dietary fiber (TDF) and non- starch polysaccharide (NSP) contents. Portions of ground materials were extracted by: n-hexane, followed by 80% methanol, n-hexane-acetic acid (95 + 5, v/v), and supercritical carbon dioxide. Defatted samples were gelatinized in water and incubated with amyloglucosidase; 95% ethanol was added to the hydrolyzates, and the residues were collected on tared glass crucibles. TDF was calculated according to a simplified enzymatic-gravimetric method developed in our laboratory, and NSP was determined as described by Englyst and coworkers. Dietary fiber values obtained with any of the extraction methods range from 3.47 g/100 g for cashews to 28.56 g/100 g for sunflower seeds. Nonstarch polysaccharide values range from 2.43 g/100 g for pecans to 5.56 g/100 g for peanuts. With the exception of sunflower seeds, samples extracted with supercritical carbon dioxide had lower TDF contents but similar amounts of NSP compared with samples extracted by the other 2 methods.
A Sensitive Method for Evaluating Condoms as Virus Barriers
Authors: Lytle C David , Duff James E , Fleharty Bruce , Bidinger Randolph L , Cyr W Howard , Routson Licia B
Published: February 2020

A standard test is needed to evaluate condoms as barriers against sexually transmitted diseases, particularly those caused by viruses. The proposed method presented here consists of a previously published simple method using physi- ologic-based conditions plus improvements to increase test sensitivity and decrease confounding factors such as contamination. Limitations of the method were determined by measuring virus penetration through small, well-defined holes. The method can detect penetration of 2 nL (2 x 10-6 mL) of challenge virus suspension as well as a hole of 2 μm diameter in a latex condom. The data also indicated that virus penetration of latex condoms occurred quickly, and the hole was then apparently closed or blocked.
Simultaneous Determination of Metoprolol-Hydrochlorothiazide and Propranolol-Hydrochlorothiazide in Combined Formulations by Derivative Spectroscopy
Authors: Prasad Challapalli V N , Bharadwaj Vipin , Narsimhan Vidya , Chowdhary Rama T , Parimoo Pyare
Published: February 2020

A derivative spectrophotometric procedure was established for simultaneous determination of propranolol HCI (PP) with hydrochlorothiazide (HTZ) and metoprolol tartrate (MTP) with HTZ in tablet preparations. The method uses first- and second-derivative spectra of tablet extract in 0.01 N NaOH solution. Ratios of analyte concentrations in the mixture were determined by the compensation technique. The zero-crossing point (ZCP) was also used to estimate the amounts of PP and HTZ in the formulations, and results were compared with those from the compensation technique. The results were found to be precise and free from interferences.
Comparison of Sorbitol MacConkey and Hemorrhagic Coli Agars for Recovery of Escherichia coli 0157:H7 from Brie, Ice Cream, and Whole Milk
Authors: Hammack Thomas S , Feng Peter , Amaguaña R Miguel , June Geraldine , Sherrod Patricia S , Andrews Wallace H
Published: February 2020

The relative efficacies of hemorrhagic coli (HC) agar and several formulations of sorbitol Mac-Conkey (SorMac) agar, with and without 0.1 % (w/v) 4-methyllumbelliferyl-ß-D-glucuronide (MUG), in recovering unstressed and heat-stressed Escherichia coli 0157:H7 from Brie cheese, ice cream, and whole milk were determined. Recovery of unstressed E. coli 0157:H7 was determined quantitatively by spread-plating diluted samples onto different agars and performing plate counts. Recovery of stressed E. coli 0157:H7 was determined qualitatively by enriching samples in modified trypticase soy broth, streaking the incubated enrichments, and isolating E. coli 0157:H7 colonies from the agars. HC agar and the SorMac agar formulations did not differ significantly in their ability to recover unstressed E. coli 0157:H7 from ice cream and whole milk; however, HC agar recovered significantly more unstressed E. coli 0157:H7 from Brie cheese than did the SorMac agar formulations. Bacteriological Analytical Manual and Oxoid SorMac agar formulations made from individual ingredients, did not differ significantly in recovering unstressed E. coli 0157:H7 from Brie cheese. The efficiency of the commercially available Oxoid SorMac agar could not be determined because of overgrowth by indigenous microflora. HC and SorMac agars did not differ significantly in recovering stressed E. coli 0157:H7 from Brie cheese, ice cream, and whole milk. MUG had no apparent effect on recovery of either stressed or unstressed E. coli 0157:H7 from the dairy foods examined.
Liquid Chromatographic Determination of Folate Monoglutamates in Fish, Meat, Egg, and Dairy Products Consumed in Finland
Authors: Vahteristo Lusa T , Ollilainen Velimatti , Varo Pertti
Published: February 2020

A liquid chromatographic (LC) method with fluorescence and UV detection was used to determine the folate contents of fish, meat, fish and meat products, chicken, eggs, and milk consumed in Finland. 5-Methyltetrahydrofolate, tetrahydrofolate, 5-formyltetrahydrofolate, 10-formylfolic acid, and folic acid from 24 commodities obtained from supermarkets, retail stores, and different outlets in the Helsinki area were analyzed. Pooled samples were extracted at pH 6.0 in the presence of antioxidants and deconjugated with hog kidney deconjugase. Very low levels of folates were detected in meat and meat products. Fresh fish, fish sticks, and chicken meat contained reasonable amounts (3–13 μg/100 g) of tetrahydrofolate and 5-methyltetrahydrofolate. Egg yolk contained high concentrations of 5-methyltetrahydrofolate (140–150 μg/100 g); 10-formylfolic acid was also detected (14–17 μg/100 g). Between-species differences in folate monoglutamate distributions were observed. The highest levels of tetrahydrofolate, >5 μg/100 g, were found in chicken meat and fillets of rainbow trout, whitefish, and baltic herring. Tetrahydrofolate was most abundant in fresh fish. LC was well suited for analyzing folate compositions of meat, fish, and other foods of animal origin. Recovery of added folates ranged from 49 to 96%.