bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid Chromatographic Determination of Ampicillin Residues in Porcine Muscle Tissue by a Multipenicillin Analytical Method: European Collaborative Study
Authors: Verdon Eric , Couëdor Pierric , Maris Pierre , Laurentie Michel ,   Collaborators:, Batjoens P , Brady B , Branzell C , Csokan P , Da Silva I , Degroodt J M , Edder P , Gomes M N N H , Kennedy D G , Keukens H , Kraus M , Lindfors E , Martin de Pozuelo M , Moretain J P , Orntoft I , Österdahl B G , Rasmussen A , Regan L , Reuvers Th , Roudaut B , Satarzadeh M , van Rhijn J A
Published: February 2020

A collaborative study involving 14 laboratories was conducted to determine residues of ampicillin in porcine muscle tissue by using a liquid chromatographic method developed for multipenicillin analysis that can quantitate 8 penicillin compounds (benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, nafcillin, oxacillin, cloxacillin, and dicloxacillin) at trace levels in muscle tissue. This method involves extraction of the penicillins with phosphate buffer, pH 9, followed cleanup and concentration on a C18 solid-phase extraction column and reaction with benzoic anhydride at 50°C and with 1,2,4-triazole and mercury(II) chloride solution, pH 9.0, at 65°C. The derivatized compounds are eluted isocratically on a C8 column with a mobile phase of acetonitrile and phosphate buffer (pH 6; 0.1M) containing sodium thiosulfate and the ion-pair reagent tetrabutylammonium hydrogen sulfate. The penicillins are detected by UV absorption at 325 nm. The limit of detection and the limit of determination (quantitation) of the method were calculated to be approximately 3–5 and 25 μg/kg, respectively, in accordance with the criteria of European Union (EU) Decision No. 93/256/EEC. In this first interlaboratory study, collaborators were instructed to monitor 4 different penicillin compounds (benzylpenicillin, phenoxymethylpenicillin, ampicillin, and amoxicillin) by analyzing 8 blind samples of muscle tissue in triplicate. These samples were prepared from 2 materials containing different concentrations of incurred ampicillin (63.5 μg/kg for material No. 1 and 358.1 μg/kg for material No. 2) and 1 blank material. The repeatability relative standard deviation and the reproducibility relative standard deviation were 10.2 and 17.4%, respectively, for material No. 1 and 7.0 and 16.0%, respectively, for material No. 2. These results demonstrate that the method is suitable for the determination of ampicillin residues in muscle tissue at the EU maximum residue limit (50 μg/kg) and above. However, the identification of positives by this procedure may need additional confirmation by techniques with greater specificity, such as liquid chromatography combined with mass spectrometry, or tandem mass spectrometry. Investigations regarding the basis of interlaboratory testing studies will further demonstrate the suitability of multiresidue methodology for detecting and quantitating other compounds in the family of penicillin antibiotics.
Visual Immunoprecipitate Assay Eight Hour Method for Detection of Enterohemorrhagic Escherichia coli O157:H7 in Raw and Cooked Beef (Modification of AOAC Official Method 996.09): Collaborative Study
Authors: Feldsine Philip T , Kerr David E , Leung Stephanie C , Lienau Andrew H , Moser Ruth F , Mui Linda A ,   Collaborators:, Anderson G , Beasley M , Clements S , Dillon J , Dombroski P , Forgey R , Gartside S , Hernandez C , Hopkins S , Johnson K , Meier J , Nguyen T , Ortega R , Reynolds J , Smith J , Solis D , Summers C , Terry J , Tuncan E , Vrana D , Warren W , Wood S
Published: February 2020

AOAC Official Method 996.09, Visual Immunoprecipitate Assay (VIP®) for Escherichia coli O157:H7, was modified to incorporate a new enrichment protocol using BioControl EHEC8™ medium for testing raw and cooked beef. Foods were tested by VIP assay and the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) enrichment procedure and the FDA Bacteriological Analytical Manual (BAM) isolation and confirmation techniques. A total of 15 collaborators participated. Raw and cooked ground beef were inoculated with E. coli O157:H7 at 2 different levels: a high level, where predominantly positive results were expect d, and a low level where fractional recovery was anticipated. Collaborators tested 396 test portions and controls by both methods, for a total of 792 test portions. Of the 396 paired test portions, 75 were positive and 230 were negative by both the VIP and culture methods. Eleven test portions were presumptively positive by VIP and could not be confirmed culturally; 32 were negative by VIP, but confirmed positive by culture; and 65 were negative by the culture method, but confirmed positive by the VIP method. There was no statistical difference between results obtained with the VIP for EHEC 8 h method and the culture method except for cooked beef, where the VIP had significantly higher recovery for one inoculation level.
N-Nitroso Compounds and Mutagens in Chinese Fermented (Sour) Corn Pancakes
Authors: Groves Frank D , Issaq Haleem , Fox Stephen , Jeffrey Alan M , Whysner John , Zhang Lian , You Wei-Cheng , Fraumeni Joseph F
Published: February 2020

Stomach cancer rates in rural Linqu County, Shandong Province, China, are exceptionally high. A previous case-control study revealed that the risk of stomach cancer was 30%higher among those who consumed sour (fermented) corn pancakes at least daily. A previous study of the sour pancakes reported volatile nitrosamines in most specimens, and almost half reportedly showed mutagenic activity. Few households currently consume sour pancakes, and the duration of fermentation has been shortened. We tested specimens of pancake batter and sour pancakes from Linqu County for mutagenic activity using the Ames test; for N-nitroso compounds (NOC) we used the Nitrolite–thermal energy analysis (TEA) method. Results of the Ames test were inconclusive: only 1 out of 15 cooked pancakes showed a positive mutagenic response, and all 15 batter specimens were negative; however, several batter specimens showed a weakly positive trend of mutagenicity with extract concentration. Our assay for total nitroso compounds was weakly positive in only 1 out of 15 specimens of sour pancake batter. That specimen was also tested by gas chromatography–TEA for nitrosaminoacids and volatile nitrosamines, but none were detected. It seems unlikely that the Chinese sour pancakes are significantly contaminated by NOC or other mutagens.
Measurement of Resistant Starch by Enzymatic Digestion in Starch and Selected Plant Materials: Collaborative Study
Authors: McCleary Barry V , McNally Marian , Rossiter Patricia ,   Collaborators:, Aman P , Amrein T , Arnouts S , Arrigoni E , Bauer L , Bavor C , Brunt K , Bryant R , Bureau S , Camire M E , Champ M , Chen Q , Chin M-L , Colilla W , Coppin J , Costa D , Crosby G , Dean J , De J. Berrios J , de Valck J , Doerfer J , Dougherty M , Eybye K , Fahey G , Femenia A , Forssell P , Gelroth J , Geske J , Hidaka H , Isaksen M F , Kettlitz B , Kozlowski F , Laerke H N , Li B , Lincoln Y , Liu Q , Martensson A-C , Mattys S , Meuser F , Monro J , Niba L , Niemann C , Panozzo J , Rossiter P , Roturier J-M , Sampson C , Sanders P , Suter D , Tas A A , Themeier H , Tudorica C , Watson R , Weber L , Weinstein M , Wilkinson M , Yen J , Zheng T
Published: February 2020

Interlaboratory performance statistics was determined for a method developed to measure the resistant starch (RS) content of selected plant food products and a range of commercial starch samples. Food materials examined contained RS (cooked kidney beans, green banana, and corn flakes) and commercial starches, most of which naturally contain, or were processed to yield, elevated RS levels. The method evaluated was optimized to yield RS values in agreement with those reported for in vivo studies. Thirty-seven laboratories tested 8 pairs of blind duplicate starch or plant material samples with RS values between 0.6 (regular maize starch) and 64% (fresh weight basis). For matrixes excluding regular maize starch, repeatability relative standard deviation (RSDr) values ranged from 1.97 to 4.2%, and reproducibility relative standard deviation (RSDR) values ranged from 4.58 to 10.9%. The range of applicability of the test is 2–64% RS. The method is not suitable for products with <1% RS (e.g., regular maize starch; 0.6% RS). For such products, RSDr and RSDR values are unacceptably high.
Determination of Ciprofloxacin with a Room-Temperature Phosphorescence Flow-Through Sensor Based on Lanthanide-Sensitized Luminescence
Authors: Cuenca-Trujillo Rosa M , Ayora-Cañada M José , Molina-Díaz Antonio
Published: February 2020

Direct measurement of the sensitized luminescence of the europium-ciprofloxacin chelate immobilized on a cationic exchanger was used to develop a flow-through room-temperature phosphorescence optosensor for determination of ciprofloxacin. The phosphorescent chelate is formed on-line at room temperature in a flow-injection system and is immobilized on a weakly acidic cation-exchange resin packed in a flow cell. Optimum experimental conditions and analytical performance are discussed in detail. The sensor response for ciprofloxacin was linear, from 1.5 × 10−6 to 2.0 × 10−5M with a relative standard deviation of 2.5% (n = 10) and a detection limit of 1.1 × 10−7M. The effect of possible interferences on sensor response was studied. The sensor was successfully tested for the determination of ciprofloxacin in pharmaceutical formulations.
Determination of Nitrogen Solubility in Dilute Pepsin Hydrochloric Acid Solution of Fishmeal: Interlaboratory Study
Authors: Miller Eric L , Bimbo Anthony P , Walters David E , Barlow Stuart M , Sheridan Berni ,   Collaborators:, Abarca I , Araos M , Batieste K M , Benios C J , Broden A , Butler B H , Caquilpan R , Cotton G , Gísladóttir G , Hernández B , Kinnari J , Marrou R , New F , Schulze C W , Sieh J , Solar M G , Sulca B , Timme E
Published: February 2020

A revised method to determine solubility of nitrogen in dilute pepsin, using 0.0002% pepsin in place of 0.2% in AOAC Official Method 971.09, was tested in 16 laboratories with 12 samples of fishmeal. Results were calculated according to 2 procedures: AOAC Official Method 971.09 and a method described in 1964 by researchers at the Torry Research Station (Aberdeen, Scotland), and generally referred to as the modified Torry method. Variations in the method of shaking and source of pepsin were also investigated. Pepsin solubility values were lower and more variable when calculated by the Torry procedure. The method of shaking apparently affected the result when calculated according to the Torry but not the AOAC method. The source of pepsin had no significant effect on between-laboratory variability, but a comparison of the 2 main sources within one laboratory resulted in highly significant differences. Based on this study, the International Fishmeal and Fish Oil Organization has adopted this new method, using 0.0002% pepsin but keeping the AOAC method of calculation. The type of shaker and source of pepsin are recommended but are not mandatory. The repeatability and reproducibility limits of this new method are 1.6 and 3.3% units of solubility, respectively.
Determination of Vegetal Proteins in Milk Powder by Enzyme-Linked Immunosorbent Assay: Interlaboratory Study
Authors: Sánchez Lourdes , Pérez María D , Puyol Pilar , Calvo Miguel , Brett Gary ,   Collaborators:, Cattaneo T M P , Haasnoot W , López-Fandiño R , Manso M A , Mata L , Razquín P , Sánchez A , Svenning C , Vegarud G E
Published: February 2020

Eight laboratories participated in a collaborative study to evaluate an enzyme-linked immunosorbent assay (ELISA) to determine soy, pea, and wheat proteins in pasteurized or ultra-high temperature (UHT) milk powders. To perform this assay, polyclonal antibodies for soy, pea, and wheat proteins were obtained from rabbit sera. Collaborators received calibration standards composed of milk powder containing 0–8% (w/w) vegetal protein in total protein and blind test samples containing approximately 1, 2, and 5% (w/w) vegetal protein. An indirect competitive ELISA was performed with a kit prepared by a participating laboratory; the kit contained plates coated with soy, pea, or wheat proteins, the corresponding specific antisera, enzyme-labeled second antibody, and substrate solution. Test samples and calibrants were extracted with phosphate-buffered saline, pH 7.4, containing 0.05% Tween and assayed with the ELISA kits. The degree of adulteration was affected by the type of heat treatment applied to the samples. The estimated percentage of vegetal protein addition was close to the theoretical value for pasteurized samples but much lower for UHT samples. For pasteurized samples, intralaboratory relative standard deviations ranged from 5 to 22% and interlaboratory relative standard deviations ranged from 14 to 34%.
On-Line Preconcentration and Determination of Cadmium in Honey Using Knotted Reactor Coupled to Flow Injection-Flame Atomic Absorption Spectrometry
Authors: Orsi Ricardo Fernández , Wuilloud Rodolfo G , Wuilloud Jorgelina C A de , Olsina Roberto A , Martinez Luis D
Published: February 2020

An on-line cadmium preconcentration and determination system implemented with flame atomic absorption spectrometry (FAAS) associated with flow injection was studied. Cadmium was retained as Cd-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol Cd-(5-Br-PADAP) complex, pH 9.3. The Cd complex was removed from the knotted reactor (KR) with ethanol. A total enhancement factor of 140 was obtained with respect to FAAS (40 for KR and 3.5 due to the use of ethanol) with preconcentration time of 120 s. The detection limit value for preconcentration of 1 g sample was 0.5 ng/g. The repeatability for 10 replicate determinations at 5.0 ng/g Cd level was 3.5% relative standard deviation, calculated from peak heights obtained. The calibration graph using the preconcentration system for Cd was linear with a correlation coefficient of 0.9990 at levels near the detection limits to at least 2000 ng/g. The method was successfully applied to determination of total Cd in honey samples.
Determination of Isoflavones in Ready-to-Feed Soy-Based Infant Formula
Authors: Johns Paul , Dowlati Lobat , Wargo Wayne
Published: February 2020

An alkaline hydrolysis/liquid chromatography (LC) method was developed for determination of isoflavones in ready-to-feed soy-based infant formula. The method consists of a 15 min methanol extraction, 10 min alkaline hydrolysis, HCl neutralization, gravity filtration, aqueous dilution, and 50 min LC analysis with UV detection at 262 and 250 nm to quantify 6 isoflavone analytes: daidzin, glycitin, genistin, daidzein, glycitein, and genistein. The concentration averages for 10 commercial batches (μg aglycone/g formula) were daidzein, 6.12 ± 1.23; glycitein, 1.19 ± 0.16; genistein, 12.8 ± 2.35; and total, 20.1 ± 3.61. Validation experiments demonstrated extraction completion and analyte stability to alkaline hydrolysis. Spike recoveries ranged from 97.6 to 104.1%, and a series of accuracy assessments showed that isoflavone concentration determined by the method was within 5% of the true value. The relative standard deviation values for repeatability ranged from 0.4 to 2.2% (n = 10), and from 0.3 to 2.7% (n = 4) for intermediate precision. Isoflavone peak purity was verified by comparing sample and standard peak area ratios (262/250 nm). The limits of detection and quantitation (μg/g formula) ranged from 0.02 to 0.05 and 0.08 to 0.18 μg/g, respectively. The difference between our concentrations and those reported by others in 1995–1998 is attributable to the well-established seasonal variation in soybean isoflavone levels. Although the method was applied exclusively to ready-to-feed formula in the present study, it is equally suitable for powder and concentrated liquid infant formulas.
Determination of Cholecalciferol (Vitamin D3) in Selected Foods by Liquid Chromatography: NMKL Collaborative Study
Authors: Staffas Anders , Nyman Arne ,   Collaborators:, Ask K , Hermansson E , Jacobsen J S , Jakobsen J , Mattila P , Smidt Olsen G , Schüep W
Published: February 2020

Results are presented from an NMKL (Nordic Committee on Food Analysis) collaborative study of a method for the determination of cholecalciferol (vitamin D3) in foods. The method is based on the addition of an internal standard (vitamin D2), followed by saponification and extraction with n-heptane. The fraction that contains vitamin D2/D3 is separated by preparative normal-phase liquid chromatography (LC), and the analytes are determined by reversed-phase LC with UV detection at 265 nm. The method was tested by 8 participating laboratories. In this study 6 different matrixes were analyzed for cholecalciferol content: milk, liquid infant formula (gruel), cooking oil, margarine, infant formula, and fish oil. The contents varied from 0.4 to 12 μg/100 g. Three matrixes (milk, gruel, and margarine) were fortified with vitamin D3. In the other matrixes, vitamin D3 was added at 3 different levels at the Swedish National Food Administration. The milk was analyzed as a blind duplicate, whereas the other matrixes were analyzed as split-level pairs. The recoveries from the samples with vitamin D3 added varied from 93 to 102%. The repeatability relative standard deviation (RSDr) values for accepted results varied between 2.2% (fish oil) and 7.4% (cooking oil), whereas the reproducibility relative standard deviation (RSDR) values varied between 6.8% (margarine) and 24% (cooking oil).
Alternative AOAC Sporicidal Test Carrier for Evaluating Peracetic Acid-Based Sterilants (Modification of AOAC Official Method 966.04)
Authors: McDonnell Gerald
Published: February 2020

Dacron suture loops were demonstrated to be inert, consistent carriers in the presence of peracetic acid-based sterilants, whereas black silk sutures had a variable preparation process and interacted with peracetic acid. In addition, Dacron suture loops provided comparable spore loading to black silk suture loops and an HCl resistance of ≥2 min. These results indicate that black silk suture loops are not appropriate carriers for assessing peracetic acid-based sterilants, and Dacron loops are an acceptable alternative. This finding is consistent with the Office of Science and Technology Laboratory (Center for Devices and Radiological Health) study which determined that “polyester suture material is a viable alternative to silk for the AOAC sporicidal test for liquid disinfectants.”
Determination of Ephedrine Alkaloids in Dietary Supplements and Botanicals by Liquid Chromatography/Tandem Mass Spectrometry: Collaborative Study
Authors: Trujillo William A , Sorenson Wendy R ,   Collaborators:, Laurensen J , Luo G , McClanahan R , Perez R , Roper C , Kotello S , Schwind B , Shevchuk C , Suen E , Sullivan D
Published: February 2020

An interlaboratory study was conducted to evaluate the accuracy and precision of a method for ephedrine-type alkaloids [i.e., norephedrine (NE), norpseudoephedrine (NPE), ephedrine (E), pseudoephedrine (PE), methylephedrine (ME), and methylpseudoephedrine (MPE)] in dietary supplements and botanicals. The amount of ephedrine-type alkaloids present was determined using liquid chromatography with tandem mass selective detection. The samples were diluted to reflect a concentration of 0.0200 to 1.00 μg/mL for each alkaloid. An internal standard was added and the alkaloids were separated using a 5 μm phenyl LC column with an ammonium acetate, glacial acetic acid, acetonitrile, and water mobile phase. Eight blind duplicates of dietary supplements or botanicals were analyzed by 10 collaborators. Included was a negative control, ephedra nevadensis, and negative controls fortified at 2 different levels with each of the 6 ephedrine-type alkaloids. The spike levels were approximately 100 and 1000 μg/g for NE, 100 and 600 μg/g for NPE, 6500 and 65 000 μg/g for E, 1000 and 10 000 μg/g for PE, 300 and 3000 μg/g for ME, and 100 and 1000 μg/g for MPE. On the basis of the accuracy and precision results for this interlaboratory study, it is recommended that this method be adopted Official First Action for the determination of 6 different individual ephedrine-type alkaloids in dietary supplements and botanicals.
Purity Assessment of Crystalline Zearalenone
Authors: Krska Rudolf , Welzig Elvira , Josephs Ralf D , Kandler Wolfgang , Pettersson Hans , MacDonald Susan , Charlton Adrian , Brereton Paul , Hametner Christian , Berner Diana , Zöllner Peter
Published: February 2020

Commercially available solid zearalenone (ZON) to be used as a certified liquid calibrant (BCR-699) in a project funded by the European Commission within the Standard Measurement and Testing program was characterized and its purity determined. The degree of purity of the ZON was examined by UV spectrophotometer, liquid chromatography (LC) with diode array and fluorescence detection, 1H and 13C-NMR spectrometry, LC–mass spectrometry (LC/MS/MS), ion chromatography (IC), and differential scanning calorimetry (DSC). The diagrams obtained from DSC analysis and the UV spectrum showed no detectable impurities. Likewise, no impurities were observed by LC analysis with both diode array and fluorescence detection. IC determination revealed negligible contamination of ZON with chloride of 0.020 ± 0.005% and nitrate of 0.016 ± 0.006%. Zearalanone (ZAN) was identified as one of 2 minor (0.2%) impurities by LC/MS/MS. The 1H-NMR measurements revealed an additional peak, which has not been previously reported in the literature. It could be identified as part of the ZON spectrum as the signal arising from the phenolic proton attached to C4'. The manufacturer states an additional contamination with 0.2% methylene chloride, which could be confirmed to an extent of 0.1% by 1H-NMR. Minor impurities, whose structures remain unknown, were discovered at 3.5 and <1 ppm. Total percentage of impurities based on NMR measurement was estimated not to exceed 1%. A purity of 99.5% with a tolerance of ±0.5% was finally attributed to the ZON studied in this project.
Crude Fat, Hexanes Extraction, in Feed, Cereal Grain, and Forage (Randall/Soxtec/Submersion Method): Collaborative Study
Authors: Thiex Nancy J , Anderson Shirley , Gildemeister Bryan ,   Collaborators:, Adcock W , Boedigheimer J , Bogren E , Coffin R , Conway K , DeBaker A , Frankenius E , Gramse M , Hogan P , Knese T , MacDonald J , M�ller J , Royle R , Russell M , Shafiee F , Shreve B , Sieh J , Spann M , Töpler E , Watts M
Published: February 2020

A method for determining crude fat in animal feed, cereal grain, and forage (plant tissue) was collaboratively studied. Crude fat was extracted from the animal feed, cereal grain, or forage material with hexanes by the Randall method, also called the Soxtec method or the submersion method. The use of hexanes provides for an alternative to diethyl ether for fat extractions. The proposed submersion method considerably decreases the extraction time required to complete a batch of samples compared to Soxhlet. The increase in throughput is very desirable in the quest for faster turnaround times and the greater efficiency in the use of labor. In addition, this method provides for reclamation of the solvent as a step of the method. The submersion method for fat extraction was previously studied for meat and meat products and was accepted as AOAC Official Method 991.36. Fourteen blind samples were sent to 14 collaborators in the United States, Sweden, Canada, and Germany. The within-laboratory relative standard deviation (repeatability) ranged from 1.23 to 5.80% for crude fat. Among-laboratory (including within) relative standard deviation (reproducibility) ranged from 1.88 to 14.1%. The method is recommended for Official First Action.
Determination of Tetracycline Antibiotics in Salmon Muscle by Liquid Chromatography Using Post-Column Derivatization with Fluorescence Detection
Authors: Pena Angelina L , Lino Celeste M , Silveira M Irene N
Published: February 2020

A simple and accurate cleanup procedure using polymeric sorbent was developed for the determination of oxytetracycline (OTC) and tetracycline (TC) residues in salmon muscle. It was applied to the analysis of 20 salmon samples during a month period. The OTC and TC residues were extracted with ethylenediaminetetracetic acid (EDTA)–McIlvaine buffer acidified at pH 4.0 and cleaned up by solid-phase extraction with a polymeric sorbent. The advantages of the polymeric sorbent over the silica-based sorbent in the cleanup of salmon muscle samples are described. A liquid chromatographic method with post-column derivatization and fluorescence detection is proposed because of its sensitivity and specificity. The average recoveries of OTC and TC from muscle salmon tissue fortified at 50, 100, and 200 μg/kg levels, ranged from 83.9 to 93.4% with a coefficient of variation between 4.09 and 5.80%. The limit of quantitation for OTC and TC in salmon muscle was 50 μg/kg.
Photostimulated Luminescence Detection of Irradiated Shellfish: International Interlaboratory Trial
Authors: Sanderson David C W , Carmichael Lorna A , Fisk Saffron ,   Collaborators:, Brown P , Burton Y , Nootenboom H , Pinnioja S , Schreiber G A , Wagner U
Published: February 2020

An interlaboratory trial was conducted to validate photostimulated luminescence (PSL) detection of irradiated shellfish. Five species of shellfish (Nephrops norvegicus, mussels, black tiger prawns, brown shrimps, and king scallops) were presented blind as nonirradiated and irradiated to 0.5 and 2.5 kGy. Precharacterization analysis of each product and treatment was performed on both whole (including shell) and intestinal samples. The results for whole samples (including shell) confirmed that the method was able to distinguish between nonirradiated and irradiated samples, regardless of dose. Intestinal data have identified that the method is dependent on the quantity and sensitivity of grits present within the intestinal tract, which can be assessed using calibration by normalization to 1 kGy. Five laboratories returned both initial screening and calibrated data and sample classification. All laboratories correctly identified all irradiated products using the screening criteria. There were no false positives. The results confirm the validity of the PSL method for shellfish, which has been adopted as a European standard method and by the Codex Alimentarius Commission. Calibration is required where only intestinal material is available. For whole samples with shell, screening alone is sufficient.
Multilaboratory Validation of a Method To Confirm Chloramphenicol in Shrimp and Crabmeat by Liquid Chromatography-Tandem Mass Spectrometry
Authors: Hammack Walter , Carson Mary C , Neuhaus Barbara K , Hurlbut Jeffrey A , Nochetto Cristina , Stuart James S , Brown Amy , Kilpatrick Donna , Youngs Kristl , Ferbos Krystle , Heller David N
Published: February 2020

An existing method for chloramphenicol (CAP) determination in shrimp using a gas chromatograph with electron capture detector was adapted for confirmation of CAP with a liquid chromatograph interfaced to a triple quadrupole mass spectrometer. CAP residues are extracted from tissue with ethyl acetate, isolated via liquid–liquid extraction, and concentrated by evaporation. Extracts are chromatographed by using a reversed-phased column and analyzed by electrospray negative mode tandem mass spectrometry. Four product ions (m/z 152, 176, 194, and 257) of precursor m/z 321 were monitored. Moving from gas chromatography to liquid chromatography–tandem mass spectrometry improved the sensitivity of the method greatly, enabling reliable confirmation of CAP residues at 0.3 μg/kg (ppb). The method meets confirmation criteria recommended by the U.S. Food and Drug Administration and 4-point identification criteria established by the European Union. With slight modifications to accommodate different equipment, the method was validated in 3 laboratories.
Determination of Ochratoxin A in Currants, Raisins, Sultanas, Mixed Dried Fruit, and Dried Figs by Immunoaffinity Column Cleanup with Liquid Chromatography: Interlaboratory Study
Authors: MacDonald Susan J , Anderson Sharron , Brereton Paul , Wood Roger ,   Collaborators:, Barrett G , Brodie C , Burdaspal P A , Conley D , Cooper J , Darroch J , Donnelly C , Embrey N , Ennion R A , Felguerias I , Griffin J , Kitching M , Knight S , Lanham J , Legarda T M , Lenartowicz P , Luis E , Lundie J C , Möller T , Norwood D , Novo R , Nyberg M , O’Donnell C , Panzarini G , Pascale M , Patel S , Paulsch W , Payne N , Rawcliffe P , Reid K , Rizzo A , Rothin A , Saari L , Stangroom S G , Swanson W , Sweet P , Thomas T , Trani R , Turpin E , van Egmond H P , Walker M , Watkins J D , Williams C
Published: February 2020

An interlaboratory study was performed on behalf of the Food Standards Agency to evaluate the effectiveness of an affinity column cleanup liquid chromatographic (LC) method for the determination of ochratoxin A in a variety of dried fruit at European regulatory limits. To ensure homogeneity before analysis, laboratory samples are normally slurried with water in the ratio of 5 parts fruit to 4 parts water, and test materials in this form were used in the study. The test portion was extracted with acidified methanol. The extract was filtered, diluted with phosphate-buffered saline, and applied to an affinity column. The column was washed and ochratoxin A was eluted with methanol. Ochratoxin A was quantified by reversed-phase LC. The use of post-column pH shift to enhance the fluorescence of ochratoxin A by the addition of 1.1M ammonia solution to the column eluant is optional. Determination was by fluorescence. Currants, sultanas, raisins, figs, and mixed fruit (comprising dried pineapple, papaya, sultanas, prunes, dates, and banana chips), both naturally contaminated and blank (very low level), were sent to 24 collaborators in 7 European countries. Participants were asked to spike test portions of all test samples at a level equivalent to 5 ng/g ochra toxin A. Average recoveries ranged from 69 to 74%. Based on results for 5 naturally contaminated test samples (blind duplicates) the relative standard deviation for repeatability (RSDr) ranged from 4.9 to 8.7%, and the relative standard deviation for reproducibility (RSDR)rangedfrom14to28%. The method showed acceptable within-and be-tween-laboratory precision for all 5 matrixes, as evidenced by HORRAT values <1.3.
Development of the Analytical Methods and Reference Materials Program for Dietary Supplements at The National Institutes of Health
Authors: Saldanha Leila G , Betz Joseph M , Coates Paul M
Published: February 2020

The need for validated analytical methods and reference materials to identify and measure constituents in dietary supplements is essential. Such methods allow for the documentation that products meet manufacturer's specifications and contain what their labels declare. In March 2003, the U.S. Food and Drug Administration issued a proposed rule that would establish specific current good manufacturing practices for dietary supplements. This proposed rule requires that companies create a quality control unit to set specifications and ensure compliance with these specifications using scientifically valid procedures. This report provides insights and lessons learned from 3 meetings the Office of Dietary Supplements (ODS) at the National Institutes of Health helped organize. These meetings were structured to (1) educate individuals about the importance and need for validated analytical methods and reference materials to identify and quantify constituents of dietary supplements; (2) identify resources required to fulfill this need; and (3) serve as a platform to obtain input from interested parties to help frame the research agenda for the Dietary Supplements Methods and Reference Materials Program within ODS. Stakeholder's opinions and views expressed at these 3 meetings are outlined in this report.
Identification and Quantification of Major Species of Arsenic in Rice
Authors: D'Amato Marilena , Forte Giovanni , Caroli Sergio
Published: February 2020

A study was undertaken to develop a method for the chemical speciation of As in rice on the basis of current knowledge in this field for use in preparing a certified reference material (CRM). Samples of the Arborio rice variety were ground to a fine powder, which was extracted under sonication with a water–methanol mixture (1 + 1, v/v). The resulting solutions were injected into a high-performance liquid chromatograph combined on-line with a quadrupole inductively coupled plasma–mass spectrometer. This hyphenated system allowed for the quantification of As species in one analytical step. Four forms of As were detected: inorganic As (III), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), and inorganic As (V) at concentrations of 88.2 ± 7.1, 50.8 ± 5.0, 15.2 ± 1.7, and 51.2 ± 3.5 ng/g, respectively. The concentration of total As was 211 ± 7 ng/g. The limits of detection (3σ criterion) and the quantitation (10σ criterion) were, respectively, as follows (in ng/g): As (III), 0.095 and 0.320; As (V), 0.082 and 0.273; MMA, 0.110 and 0.367; and DMA, 0.145 and 0.480. Ten hours were needed for the extraction procedure, 6 h for the evaporation, and 30 min for quantification of the analytes. This investigation was performed in the frame of a European Commission Project on the feasibility of CRMs for As and Se species.
Rapid Forensic Selected Reaction Monitoring Liquid Chromatography/Mass Spectrometry Determination of Ionophore Antibiotics Found at Toxic Levels in Animal Feeds
Authors: Ebel Joseph G , Wachs Timothy , Henion Jack D
Published: February 2020

A rapid, accurate, and selective method was developed for the forensic determination of ionophore antibiotics in animal feeds. A simple extraction procedure and liquid chromatography/tandem mass spectrometry (LC/MS/MS) in the selected reaction monitoring (SRM) mode were used for rapid identification and confirmation of monensin and lasalocid in feed samples and for quantitation of monensin. Extracts from a homogenous portion of ground feeds were prepared using liquid–solid extraction and liquid–liquid extraction techniques. Feed extracts were further purified by a simple defatting and solvent wash step and then concentrated to dryness. Feed extract residues were reconstituted in 1 mL LC mobile phase and a 2 μL aliquot injected into the SRM LC/MS system. The latter system used a C18, 100 × 2.0 mm, LC column coupled to a PE-Sciex API 2000 tandem triple quadrupole mass spectrometer equipped with a TurboIonSpray LC/MS interface. Feed samples were extracted and analyzed for the determination of monensin and lasalocid within a couple of hours. Control feed samples fortified with monensin at concentrations from 50 ppb to 5 ppm provided a linear response and calibration curve across this range with a correlation coefficient of 0.996.
Dietary Fiber: The Influence of Definition on Analysis and Regulation
Authors: DeVries Jonathan W
Published: February 2020

Since 1953 when the term “dietary fiber” was coined, there has been concern about accurately defining this macronutrient component of the human diet. Proper and adequate analytical methodology and food labeling regulations are dependent upon an accurate definition. Health impact studies also depend upon an accurate and meaningful definition along with relevant methodology to provide data of adequate quality for epidemiological and clinical studies. The scientific communities associated with dietary fiber within AOAC INTERNATIONAL have been the leaders in bringing consensus to the dietary fiber definition and method validation for over a quarter of a century. The consensus definition and subsequent methodology have served as the base for regulations worldwide with regard to dietary fiber labeling and health claims. Recently, there has been renewed interest in reviewing the dietary fiber definition and updating it if the review indicates such a need. The American Association of Cereal Chemists completed an effort that provides a continuum for the historical scientific and regulatory efforts while allowing for inclusion of future discoveries into a framework based upon the knowledge gained in the past. Such a definition will provide for transparent and workable regulations with regard to dietary fiber, and will allow the dietary fiber scientific community of AOAC to validate relevant methods. The Food Nutrition Board of the Institute of Medicine of the National Academies has published a set of definitions disconnected from the historical scientific base that do not provide a relevant basis for either adequate methodology, health studies or workable regulations.
Nondigestible Oligosaccharides as Dietary Fiber
Authors: Meyer P Diederick
Published: February 2020

An overview is presented of the most important oligosaccharides that are classified as dietary fiber. Their occurrence and structures as well as their various physiological effects are described. The scientific evidence for health effects, associated with these physiological effects, along with the applications in the food industry, are also discussed.
Resistant Starch: Metabolic Effects and Potential Health Benefits
Authors: Higgins Janine A
Published: February 2020

Although there is strong evidence that the amount and type of fat in the diet can have dramatic effects on metabolism, the case for carbohydrate subtypes influencing metabolic parameters is emerging. By definition, resistant starch (RS) is any starch that is not digested in the small intestine but passes to the large bowel. Here, RS is a good substrate for fermentation which gives rise to an increase in short-chain fatty acid production. The differing rates of absorption between RS and digestible starch are thought to denote their differential metabolic responses. RS intake is associated with several changes in metabolism which may confer some health benefits. RS intake seems to decrease postprandial glycemic and insulinemic responses, lower plasma cholesterol and triglyceride concentrations, improve whole body insulin sensitivity, increase satiety, and reduce fat storage. These properties make RS an attractive dietary target for the prevention of diseases associated with dyslipidemia and insulin resistance as well as the development of weight loss diets and dietary therapies for the treatment of Type 2 diabetes and coronary heart disease. This review analyzes the body of literature examining the metabolic effects of RS consumption and discusses possible mechanisms whereby increased short-chain fatty acid production in the bowel could account for some of these effects. The effects of RS in the large bowel per se are the topic of other reviews and are not addressed in this paper.
Multicenter Validation of PCR-Based Method for Detection of Salmonella in Chicken and Pig Samples
Authors: Malorny Burkhard , Cook Nigel , D'Agostino Martin , De Medici Dario , Croci Luciana , Abdulmawjood Amir , Fach Patrick , Karpiskova Renata , Aymerich Teresa , Kwaitek Krysztof , Kuchta Tomas , Hoorfar Jeffrey
Published: February 2020

As part of a standardization project, an interlaboratory trial including 15 laboratories from 13 European countries was conducted to evaluate the performance of a noproprietary polymerase chain reaction (PCR)-based method for the detection of Salmonella on artificially contaminated chicken rinse and pig swab samples. The 3 levels were 1–10, 10–100, and 100–1000 colony-forming units (CFU)/100 mL. Sample preparations, including inoculation and pre-enrichment in buffered peptone water (BPW), were performed centrally in a German laboratory; the pre-PCR sample preparation (by a resin-based method) and PCR assay (gel electrophoresis detection) were performed by the receiving laboratories. Aliquots of BPW enrichment cultures were sent to the participants, who analyzed them using a thermal lysis procedure followed by a validated Salmonella-specific PCR assay. The results were reported as negative or positive. Outlier results caused, for example, by gross departures from the experimental protocol, were omitted from the analysis. For both the chicken rinse and the pig swab samples, the diagnostic sensitivity was 100%, with 100% accordance (repeatability) and concordance (reproducibility). The diagnostic specificity was 80.1% (with 85.7% accordance and 67.5% concordance) for chicken rinse, and 91.7% (with 100% accordance and 83.3% concordance) for pig swab. Thus, the interlaboratory variation due to personnel, reagents, thermal cyclers, etc., did not affect the performance of the method, which will be proposed as part of a developing international PCR standard.
Method Validation for Detection and Quantification of Cocoa Butter Equivalents in Cocoa Butter and Plain Chocolate
Authors: Buchgraber Manuela , Ulberth Franz , Anklam Elke ,   Collaborators:, Bernaert H , Cleenewerck B , Hummert C , Lamoureux T , Lomnitz A , Marchioni E , Matissek; R , Medina B , Rodriguez-Estrada M T , Timms R E , Veretout O , Wachter N , Zijderfeld H
Published: February 2020

A European interlaboratory study was conducted to validate an analytical procedure for the detection and quantification of cocoa butter equivalents in cocoa butter and plain chocolate. In principle, the fat obtained from plain chocolate according to the Soxhlet principle is separated by high-resolution capillary gas chromatography into triacylglycerol fractions according to their acyl-C-numbers, and within a given number, also according to unsaturation. The presence of cocoa butter equivalents is detected by linear regression analysis applied to the relative proportions of the 3 main triacylglycerol fractions of the fat analyzed. The amount of the cocoa butter equivalent admixture is estimated by partial least-squares regression analysis applied to the relative proportions of the 5 main triacylglycerols. Cocoa butter equivalent admixtures were detected down to a level of 2% related to the fat phase, corresponding to 0.6% in chocolate (assumed fat content of chocolate, 30%), without false-positive or -negative results. By using a quantification model based on partial least-squares regression analysis, the predicted cocoa butter equivalent amounts were in close agreement with the actual values. The applied model performed well at the level of the statutory limit of 5% cocoa butter equivalent addition to chocolate with a prediction error of 0.6%, assuming a chocolate fat content of 30%.
Liquid Chromatographic Method for Nicarbazin in Broiler Feeds and Premixtures: Development, Validation, and Interlaboratory Study
Authors: de Jong Jacob , Tomassen Marinka , Driessen Jaap , Keukens Henk , Putzka Hans-Artur , Brambilla Gianfranco ,   Collaborators:, Antalick J P , Biancotto G , Brambilla G , Checa-Moreno R , Cowles J , Faggionato E , Felgueiras I , Haustraete K , Johanssen F , Margry R , Michels K , Nunes da Costa J , Putzka H A , Schreuder C , Schwadorf K , Testa C , Ubaldi A , van der Kamp H , Van Schalm K
Published: February 2020

A reversed-phase liquid chromatography method for nicarbazin in broiler feeds and premixtures was developed, validated, and interlaboratory studied. The extraction solvent was an acetonitrile–methanol (1 + 1) mixture. For feedingstuffs, water was also added. The 4,4′-dinitrocarbanilide moiety of nicarbazin was detected at a wavelength of 350 nm. Recovery was ≥ 87%. At 20 mg/kg, the repeatability was 0.7% and the within-laboratory reproducibility was 2.7%. The limit of determination was <20 mg/kg. Other feed additives did not interfere in the assay that proved to be applicable to broiler feeds from different European Union countries. In an interlaboratory study, 4 positive broiler feeds, 1 blank pig feed, and 1 broiler premixture were analyzed by 19 laboratories using the method developed in this study. The relative standard deviation for repeatability (RSDr) of the feedingstuffs (20–240 mg/kg) varied between 2.6 and 10.2%. The HORRAT ranged between 0.70 and 1.22. Recoveries were 91–108%. Three laboratories detected small signals in the blind blank samples, ranging from 0.4 to 2 mg/kg. For the premixture, acceptable results for reproducibility could only be obtained after the sample weight and volume of extraction had been doubled. To avoid excessive dilution of the extracts, the range of the calibration curve had also been doubled. With this modified method, the RSDr was 5.7% and the HORRAT was 1.95 (10 laboratories).
Liquid Chromatographic Method to Determine Narasin in Feedingstuffs and Premixtures: Development, Validation, and Interlaboratory Study
Authors: Thalmann Alfred , Wagner Klaus , Tomassen Marinka , Driessen Jaap , de Jong Jacob ,   Collaborators:, Antalick J , Biancotto G , Cowles J , Felgueiras I , Haustraete K , Johannsen F , Muhonen; R , Nunes da Costa J , Pløger A , Shearan P , van der Kamp H , van Schalm K , Wagner K
Published: February 2020

A reversed-phase liquid chromatography (LC) method for narasin in feedingstuffs and premixtures was developed, validated, and interlaboratory studied. The extraction solvent was methanol–K2HPO4 solution (9 + 1, v/v). Narasin was detected at 600 nm after post-column derivatization with dimethylamino-benzaldehyde. Recovery was >90%. The repeatability (RSDr) in feed (20–140 mg/kg) ranged between 1.2 and 10.5%; the within-laboratory reproducibility (RSDR) ranged between 2.2 and 4.9%. The limit of determination was <20 mg/kg. Other feed additives did not interfere in the assay. The method showed ruggedness against changes in the composition of extraction solvent, eluent, and conditions for post-column reactions. In an interlaboratory study, 5 broiler feeds (4 positive, 1 blank) and 1 premixture were analyzed by 13 laboratories. The RSDr of the feedingstuffs (20–120 mg/kg) varied between 2.17 and 7.57%. The HORRAT ranged between 0.77 and 0.88, with recoveries between 82 and 104%. One laboratory detected small signals in the blank sample, calculated as 0.6 and 2.8 mg/kg. For the premixture, acceptable results for reproducibility could only be obtained after modification of the method: the RSDr was 4.42% and the HORRAT was 1.56 (12 laboratories).
Contribution of Sampling to the Variability of Pesticide Residue Data
Authors: Ambrus Árpád , Soboleva Eugenia
Published: February 2020

The uneven distribution of pesticide residues among the treated objects leads to an inevitable variability of pesticide residue levels measured in the samples, which may significantly contribute to the combined uncertainty of the analytical results. A total of 8844 unit-crop residue data derived from 57 lots and 19 field trials were evaluated to determine the characteristic features of residue distribution in unit crops and composite samples. The average residue levels and the corresponding coefficient of variation (CV) values obtained for individual units taken from a given lot showed wide variation from lot to lot. There was no significant difference between the CVs of residue levels in sample sets of various unit crops or composite sample populations of different sizes taken from various crops. The CV values for levels of residues taken from individual lots followed normal distribution. Very good correlation was found between the CVs of the parent and sample populations. The experimentally obtained values were very close to those expected on the basis of the central limit theorem. The estimated typical relative standard uncertainties of sampling medium-size crops for pesticide residue analysis in the cases of sample sizes of 5, 10, and 25 were 37, 25, and 16%, respectively.