bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Total Vitamin C in Fruit Juices and Related Products by Liquid Chromatography: Interlaboratory Study
Authors: Brause Allan R , Woollard David C , Indyk Harvey E ,   Collaborators:, Acar J , Adadevoh K , Cherix G , Durst B , Eisele T , Elkins E , Foos J , Hammack S , Hammond D , Hesford F , Hischenhuber C , Hong V , Huang C J , Kirksey S , Kline L , Kruger D , Lawson M J , Lea A , Martin G , Parkih A , Weiss J , Wilhelmsen E , Woodward B , Wrolstad R , Zygmunt L
Published: February 2020

A interlaboratory study was conducted to evaluate a liquid chromatographic (LC) procedure for the determination of total vitamin C in foods at levels of 5–60 mg/100 g. Emphasis was placed on fruit juices, although selected foods were also included in the study. Following dissolution of sample in water, endogenous dehydroascorbic acid was converted to ascorbic acid by precolumn reduction with dithiothreitol at neutral pH. Total ascorbate was determined by C18 reversed-phase LC with a phosphate eluent at pH 2.5, incorporating dithiothreitol to maintain vitamin C in the reduced form, and UV detection at 254 nm. Seven types of fruit juices and foods were tested by 19 collaborators in 7 countries. Three duplicate juices and foods met the criteria for Youden pairs and yielded repeatability relative standard deviation of 5.80–14.66%. Reproducibility relative standard deviation ranged from 6.36 to 35.54% (n = 10) with HORRAT values of 0.82–4.04. The LC method is suitable for routine use in fruit products and foods containing >5 mg/100 g vitamin C and is recommended for further validation by AOAC INTERNATIONAL and International Fruit Juice Union.
Fast and Easy Multiresidue Method Employing Acetonitrile Extraction/Partitioning and “Dispersive Solid-Phase Extraction” for the Determination of Pesticide Residues in Produce
Authors: Anastassiades Michelangelo , Lehotay Steven J , Štajnbaher Darinka , Schenck Frank J
Published: February 2020

A simple, fast, and inexpensive method for the determination of pesticide residues in fruits and vegetables is introduced. The procedure involves initial single-phase extraction of 10 g sample with 10 mL acetonitrile, followed by liquid–liquid partitioning formed by addition of 4 g anhydrous MgSO4 plus 1 g NaCl. Removal of residual water and cleanup are performed simultaneously by using a rapid procedure called dispersive solid-phase extraction (dispersive-SPE), in which 150 mg anhydrous MgSO4 and 25 mg primary secondary amine (PSA) sorbent are simply mixed with 1 mL acetonitrile extract. The dispersive-SPE with PSA effectively removes many polar matrix components, such as organic acids, certain polar pigments, and sugars, to some extent from the food extracts. Gas chromatography/mass spectrometry (GC/MS) is then used for quantitative and confirmatory analysis of GC-amenable pesticides. Recoveries between 85 and 101% (mostly >95%) and repeatabilities typically <5% have been achieved for a wide range of fortified pesticides, including very polar and basic compounds such as methamidophos, acephate, omethoate, imazalil, and thiabendazole. Using this method, a single chemist can prepare a batch of 6 previously chopped samples in <30 min with approximately $1 (U.S.) of materials per sample.
Determination of Metals in Composite Diet Samples by Inductively Coupled Plasma-Mass Spectrometry
Authors: Melnyk Lisa Jo , Morgan Jeffrey N , Fernando Reshan , Pellizzari Edo D , Akinbo Olujide
Published: February 2020

A study was conducted to evaluate the applicability of inductively coupled plasma-mass spectrometry (ICP-MS) techniques for determination of metals in composite diets. Aluminum, cadmium, chromium, copper, lead, manganese, nickel, vanadium, and zinc were determined by this method. Atmospheric pressure microwave digestion was used to solubilize analytes in homogenized composite diet samples, and this procedure was followed by ICP-MS analysis. Recovery of certified elements from standard reference materials ranged from 92 to 119% with relative standard deviations (RSDs) of 0.4–1.9%. Recovery of elements from fortified composite diet samples ranged from 75 to 129% with RSDs of 0–11.3%. Limits of detection ranged from 1 to 1700 ng/g; high values were due to significant amounts of certain elements naturally present in composite diets. Results of this study demonstrate that low-resolution quadrupole-based ICP-MS provides precise and accurate measurements of the elements tested in composite diet samples.
Survey of Residual Tetracycline Antibiotics and Sulfa Drugs in Kidneys of Diseased Animals in the Aichi Prefecture, Japan (1995–1999)
Authors: Oka Hisao , Ito Yuko , Goto Tomomi , Minami Tamae , Yamamoto Isao , Matsumoto Hiroshi , Mizuno Yoshihisa , Tsuruta Masukiyo , Hayashi Itsuki
Published: February 2020

Animal kidneys were collected in order to survey the incidence of tetracycline (TC) antibiotics and sulfa (SA) drug residues in slaughtered animals that did not pass inspection for human consumption by the Japanese Food Sanitation Law and the Meat Inspection Law at the slaughterhouses in Aichi Prefecture, Japan, from April 1995 to March 2000. The kidneys were analyzed by AOAC Official Method 995.09 for TCs and our previously reported liquid chromatographic method for SAs. Among 292 animals (94 cattle and 198 pigs), 106 (36.6%) and 41 (14.0%) contained TCs and SAs, respectively, including chlortetracycline, 59 (20.2%); oxytetracycline, 47 (16.1%); sulfamonomethoxine, 35 (12.0%); sulfadimethoxine and sulfamethoxazole, each 2 (0.7%); and sulfamerazine and sulfisoxazole, each 1 (0.3%). A small number of animals (5 cattle and 9 pigs) contained more than one drug residue. The frequency of residue detections was significantly higher for TCs than SAs in both cattle and pig kidneys (p < 0.001).
Determination of Chloramphenicol in Bovine Milk by Liquid Chromatography/Tandem Mass Spectrometry
Authors: Sørensen Lambert K , Elbæk Tina H , Hansen Helga
Published: February 2020

A rapid confirmatory liquid chromatographic/tandem mass spectrometic method was developed for determination of chloramphenicol in bovine milk. Chloramphenicol was extracted directly from milk by solid-phase extraction on a C18 cartridge. The extract was further cleaned up on neutral aluminium oxide. Three transition products were monitored in negative ion mode after atmospheric pressure chemical ionization. The detection capability related to the transition product of lowest abundance was 0.03 μg/kg. The mean recovery was 90% at levels of 0.1–0.2 μg/kg. The relative repeatability standard deviations were 4.3, 3.8, and 2.8% at levels of 0.1, 0.2, and 1.0 μg/kg, respectively.
Determination of Phenylalanine and Tyrosine by Liquid Chromatography/Mass Spectrometry
Authors: Andrensek Samo , Golc-Wondra Alenka , Prosek Mirko
Published: February 2020

Phenylketonuria is a common metabolic disorder disease. Those affected appear normal at birth, but without treatment they develop severe psychomotor retardation. Throughout life, they must control their blood levels of phenylalanine (Phe) and consume a diet containing adequate amounts of Phe and tyrosine (Tyr). We have developed a liquid chromatographic/mass spectrometric (LC/MS) method for the quantitative evaluation of Phe and Tyr in food samples. This method takes advantage of the good separation of LC and the selective and reliable quantification provided by MS in the electrospray ionization mode. The LC/MS method is very suitable for the determination of selected amino acids in various matrixes. It is sensitive to levels as low as about 0.30 ppm for Tyr and 0.70 ppm for Phe and robust. Nearly 100 nondietary food samples were analyzed by the developed method.
Effectiveness of Temperature Modification in Decreasing the Bias in Milk Fat Test Results Between the Babcock and Ether Extraction Methods
Authors: Lynch Joanna M , Barbano David M , Healy Patrick A , Fleming J Richard
Published: February 2020

Both the Babcock (AOAC Method 989.04, revised Final Action 2000) and modified Mojonnier ether extraction (AOAC Method 989.05) methods are used in the dairy industry to determine the fat content of milk. Prior to revision in 1997, the Babcock method gave consistently higher fat test results than did the ether extraction. In 1997, a modification of the Babcock method was introduced to bring the results of the Babcock test into closer agreement with the ether extraction. The Babcock method was modified by lowering the temperatures used at various points in the method from about 57.5 to 48°C to increase the density of the material in the Babcock column. A collaborative study of the modification indicated it was successful in bringing the Babcock and ether extraction results into agreement but suggested that performance of the modified method was not as good as that of the unmodified method. In the present study, substantial evidence is presented to validate the success of the Babcock modification in bringing test results into agreement with ether extraction, and to document that temperature modification does not adversely affect method performance. Data were evaluated from an on-going proficiency testing program where 8–15 laboratories tested 7 milk samples in blind duplicate once every 2 months. Laboratories used the unmodified method from 1995 through 1996 and the modified method from 1998 through 1999. Compared with ether extraction, test results from the unmodified Babcock test were consistently higher by an average of 0.022% fat. For the modified Babcock test, average test results were –0.003% fat lower than with ether extraction and not significantly different from zero. AOAC method performance statistics (within-and between-laboratory precision) were equivalent for both the unmodified (Sr = 0.027, SR = 0.041, RSDr = 0.73%, RSDR = 1.08%) and modified (Sr = 0.023, SR = 0.038, RSDr = 0.60%, RSDR = 1.02%) Babcock methods. Modification of the Babcock method was successful in bringing test results into agreement with those of ether extraction.
3M™ Petrifilm™ Enterobacteriaceae Count Plate Method for Enumeration of Enterobacteriaceae in Selected Foods: Collaborative Study
Authors: Silbernagel Karen M , Lindberg Kathryn G ,   Collaborators:, Beatty S , Bell K , Boylston T , Brock G , Bryant L , DeSmet M , Eifert J , Grzanek K , Pulasani S , Saunders L , Scantling M , Wilson P
Published: February 2020

The practice of detecting and enumerating all oxidase-negative, glucose-fermenting-Gram-negative rods (i.e., the family Enterobacteriaceae) isused to indicate unsanitary or inadequate food processing conditions. The objective of this interlaboratory collaborative study was to evaluate and compare the methods described in Standard Methods for the Examination of Dairy Products (SMEDP) and the Compendium of Methods for the Microbiological Examination of Foods (Compendium) with a commercial product, the 3M™ Petrifilm™ Enterobacteriaceae Count Plate, for the recovery of Enterobacteriaceae in foods. Six foods—cheddar cheese, milk, flour, frozen prepared meals, frozen broccoli, and nut pieces—were analyzed for Enterobacteriaceae by 12 collaborating laboratories. For each food tested, the collaborators received 8 blind test portions consisting of a control test portion and 3 levels of inoculated test portion, each in duplicate. Each test portion was tested by the Petrifilm Enterobacteriaceae Count Plate method as well as the SMEDP or Compendium methods. The precision estimates (repeat-ability or within-laboratory variation, and reproducibility or between-laboratory variation) were calculated with standard statistical techniques.
Policy on Characterization of Antibodies Used in Immunochemical Methods of Analysis for Mycotoxins and Phycotoxins
Authors: Fremy J Marc , Usleber Ewald ,   Collaborators:, Chu F , Garthwaite I , Lee A , Maragos C , Ware G
Published: February 2020

The purpose of this document is to provide a policy on antibody characterization for conducting AOAC collaborative studies for immunochemical methods submitted for AOAC®Official MethodsSM Program status. The policy defines recommended information and characteristics to be provided by the Study Director, in the protocol of the collaborative study, for approval by AOAC. The document specifies parameters for characterization of antibodies used as biological reagent in the protocol of validation of immunochemical methods for the determination of mycotoxins and phycotoxins. These recommendations are applicable to the validation of any method, whether proprietary or non-proprietary, that is submitted to AOAC for Official Methods of AnalysisSM status recognition.
Computation of HORRAT Values
Authors: McClure Foster D , Lee Jung-Keun
Published: February 2020

The formula for the Horwitz ratio (HORRAT) as presented in the Study Director's Manual of AOAC INTERNATIONAL is applicable only when the concentration is in the unit/unit form (e.g., μg/μg, g/g, etc.). When the analyte concentration is a trace or mass fraction amount (e.g., μg/g), the formula generates incorrect HORRAT values. Alternative calculation procedures are presented to circumvent such problems.
Crude Fat, Diethyl Ether 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 diethyl ether by the Randall method, also called the Soxtec method or the submersion method. The proposed submersion method considerably decreases the extraction time required to complete a batch of samples. 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 12 collaborators in the United States, Sweden, Canada, and Germany. The within-laboratory relative standard deviation (repeatability) ranged from 1.09 to 9.26% for crude fat. Among-laboratory (including within) relative standard deviation (reproducibility) ranged from 1.0 to 21.0%. The method is recommended for Official First Action.
Comparison of Solid-Phase Extraction and Micro-Solid-Phase Extraction for Liquid Chromatography/Mass Spectrometry Analysis of Pesticides in Water Samples
Authors: Famiglini Giorgio , Trufelli Helga , Pierini Elisabetta , De Simoni Elisa , Mangani Filippo , Cappiello Achille
Published: February 2020

Our recent on-line solid-phase extraction (SPE) device for micro-liquid chromatography, known as micro-solid-phase extraction (μSPE), was compared with traditional SPE for the analysis, from aqueous samples, of 4 pesticides belonging to different classes. Two different kinds of adsorbents, C18 and graphitized carbon black, were tested. A 2-stage ion trap mass spectrometer, equipped with homemade microflow electrospray ion (ESI) source, was used. Detection limits with a signal-to-noise ratio of 3:1 for both extraction methods were in the range of 0.1 μg/L for all compounds. However, better recoveries were obtained when μSPE traps were used.
A Technique to Recover Tracer as Carboxyl–Carbon and α-Nitrogen from Amino Acids in Soil Hydrolysates
Authors: Marsh Kerri L , Mulvaney Richard L , Sims Gerald K
Published: February 2020

Isotope analysis of biochemical compounds provides an unequivocal means for detecting assimilation of tracer C and N into microbial biomass. A diffusion method recently developed to determine amino acid-N by ninhydrin oxidation of soil hydrolysates was modified to permit simultaneous collection of the CO2 liberated during this oxidation. In the technique described herein, this is accomplished after removal of (NH4+ + amino sugar)–N, by performing ninhydrin oxidation at 90°C for 7 h in a 1.9 L Mason jar sealed with a lid equipped to support a petri dish containing 5 mL 0.2N NaOH. Recoveries of carboxyl-C and α-N ranged from 98 to 101% in evaluations with standard solutions of amino acids, whereas these recoveries exceeded 90% for 14C and 94% for 15N when soil hydrolysates amended with labeled amino acids were analyzed.
Speciation of Arsenic in Chicken Meat by Anion-Exchange Liquid Chromatography with Inductively Coupled Plasma-Mass Spectrometry
Authors: Polatajko Aleksandra , Szpunar Joanna
Published: February 2020

A method was developed for speciation analysis of arsenic in chicken meat. Different procedures were optimized for the recovery of arsenic compounds without destroying the original compounds, and 2 anion-exchange liquid chromatography columns were compared for the separation of arsenic species prior to on-line detection by inductively coupled plasma-mass spectrometry. The 2 species found were dimethylarsinic acid (106 ± 5 ng/g) and arsenobetaine (37 ± 4 ng/g). The stability of arsenic species in a chicken meat candidate reference material for at least 12 months was demonstrated.
Gas Chromatographic/Mass Spectrometric Determination of Flumioxazin Extracted from Soil and Water
Authors: Ferrell Jason A , Vencill William K
Published: February 2020

A method was developed for determining flumioxazin in soil and water. Recovery efficiencies for solid-phase extraction (SPE) of flumioxazin from deionized, well, and surface water were between 72 and 77%. SPE was superior to liquid–liquid extraction, using water–hexane and water–chloroform emulsions, which resulted in retrieval efficiencies of 25 and 22%, respectively. However, liquid–liquid extraction with ethyl acetate improved recovery of total flumioxazin to >64%. Extraction from soil samples by direct solvent/soil extraction methods recovered between 18 and 76% of applied flumioxazin, depending on the solvent combination used. However, the use of accelerated solvent extraction techniques resulted in a 106 ± 8% recovery of flumioxazin from soil. In analysis by capillary gas chromatography with mass selective detection, flumioxazin had a calculated limit of detection of 9 ng/mL with a retention time of 16.66 min.
Quantitative Determination of Paralytic Shellfish Poisoning Toxins in Shellfish Using Prechromatographic Oxidation and Liquid Chromatography with Fluorescence Detection: Interlaboratory Study
Authors: Lawrence James F , Niedzwiadek Barbara , Menard Cathie ,   Collaborators:, Biré Ronel , A. Burdaspal Pedro , Ceredi Alfiero , Davis Brad , Dias Elsa , Eaglesham Goeff , Franca Susana , Gallacher Susan , Graham Dave , Hald Benedicte , Heinze Lutz , Hellwig Egon , M. Jonker Klaas , Kapp Katrin , Krys Sophie , Kurz Karl , Lacaze Jean-Pierre , Gago Martinez Ana , McNabb Paul , Ménard Cathie , Milandri Anna , Nsengiyumva Chrysostome , Pereira Paulo , Pineiro Nuria , Poletti Roberto , Riddell Greg , Rojas de Astudillo Luisa , Selwood Andy , Stern Alfred , Tiebach Reinhard , van den Top Hester , P. van Egmond Hans , Wezenbeek Paul , Chang Yen Ivan
Published: February 2020

An interlaboratory study was conducted for the determination of paralytic shellfish poisoning (PSP) toxins in shellfish. The method used liquid chromatography with fluorescence detection after prechromatographic oxidation of the toxins with hydrogen peroxide and periodate. The PSP toxins studied were saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins 2 and 3 (GTX2,3 together), gonyautoxins 1 and 4 (GTX1,4 together), decarbamoyl saxitoxin (dcSTX), B-1 (GTX5), C-1 and C-2 (C1,2 together), and C-3 and C-4 (C3,4 together). B-2 (GTX6) toxin was also included, but for qualitative identification only. Samples of mussels, both blank and naturally contaminated, were mixed and homogenized to provide a variety of PSP toxin mixtures and concentration levels. The same procedure was followed with samples of clams, oysters, and scallops. Twenty-one samples in total were sent to 21 collaborators who agreed to participate in the study. Results were obtained from 18 laboratories representing 14 different countries.
Studies of Polyester Fiber as Carrier for Microbes in a Quantitative Test Method for Disinfectants
Authors: Miner Norman , Harris Valerie , Stumph Sara , Cobb Amanda , Ortiz Jennifer
Published: February 2020

Tests were conducted by a Task Force on Disinfectant Test Methods that was appointed to investigate controversies regarding the accuracy of AOAC test methods for disinfectants as presented in AOAC's Official Methods of Analysis, Chapter 6. The general principles for new and improved AOAC tests are discussed, and a disinfectant test using microbes labeled onto a polyester fiber surface is described. The quantitative test measures the survival of test microbes as a function of exposure time as well as the exposure conditions required to kill 6 log10 of the test microbes. The time required was similar to that for the kinetics of the kill of Bacillus subtilis-labeled cylinders as tested by methods of the AOAC Sporicidal Test 966.04.
New Internal Standard for Quantitative Determination of Oxyphytosterols by Gas Chromatography
Authors: Grandgirard André , Cabaret Stéphanie , Martine Lucy , Berdeaux Olivier
Published: February 2020

A study was conducted to develop a new internal standard for the quantitative determination of oxyphytosterols. Tests on 5α-androsten-3β,17β-diol; 5α-androstan-3β, 17β-diol; 5-pregnen-3β,20α-diol; and 5α-pregnan-3β,20β-diolshowed that these compounds were not fully adequate. However, the compound 3β,22-dihydroxy-20-homo-5-pregnene, synthesized in 4 steps, resulted in a promising internal standard, with a molecule similar to hydroxysterols; retention time as trimethylsilyl in gas chromatography comprised between 5α-cholestane and 7α-hydroxycholesterol; clear mass spectrum in electronic impact mass spectrometry, with several intense ions suitable for selected ion monitoring-mass spectrometry. Further studies are necessary to observe the behavior of these compounds during the entire analytical procedure.
Inhibition of Stigmasterol Oxidation by Antioxidants in Purified Sunflower Oil
Authors: Rudzińska Magdalena , Korczak Józef , Gramza Anna , Wąsowicz Erwin , Dutta Paresh C
Published: February 2020

A study was conducted to analyze the effect of the antioxidants butylated hydroxytoluene, α-tocopherol, ethanolic extracts of rosemary, and green tea on stigmasterol resistance against degradation and formation of its oxidation products in purified triacylglycerols (TAG) from sunflower oil. The content of stigmasterol and its oxidation products 7α-and 7β-hydroxy, α-and β-epoxy, triol, and 7-ketostigmasterol were determined during incubation at 60°C for 3, 6, and 9 days. In addition, peroxide value and fatty acid composition were also determined in the samples. Correlation between the levels of the accumulated stigmasterol oxides and peroxide value of the TAG with antioxidants during incubation was significant only for rosemary extract (R = 0.6799, p < 0.05). The lack of correlation precludes the use of peroxide values to determine the level of sterol oxidation products in the used model system. Correlation between stigmasterol content and the level of stigmasterol oxides was significant for all samples (R = 0.8874, p < 0.05). The total increase of the stigmasterol oxidation products was the lowest in samples with α-tocopherol, but the content of stigmasterol-triol increased the most in this sample. In all the analyzed samples, α-epoxy-stigmasterol was formed in the highest amounts among the analyzed stigmasterol oxidation products.
Overview of Infrared Methodologies for trans Fat Determination
Authors: Mossoba Magdi M , Yurawecz Martin P , Delmonte Pierluigi , Kramer John K G
Published: February 2020

trans Fatty acids are present in a variety of foods like dairy products, but the major sources are products that contain commercially hydrogenated fats. Some studies have shown that trans fatty acids elevate levels of serum low-density lipoprotein (LDL)-cholesterol and lower high-density lipoprotein (HDL)-cholesterol. The quantitation and identification of trans fatty acid isomers is difficult because of the wide range of positional monoene, diene, and triene fatty acid isomers present in hydrogenated oils. This is complicated by the cis positional isomers that are also present, as well as the lack of commercial chromatographic standards for many fatty acid isomers. In this review, infrared methodologies for the determination of total trans fat are presented. Using an attenuated total reflection (ATR) infrared cell, a novel Fourier transform infrared (FTIR) spectroscopic method that was developed for the rapid (5 min) quantitation of the total trans fatty acid levels in neat (without solvent) fats and oils measured as triacylglycerols (TAG) is discussed. TAG required no derivatization, but had to be melted prior to measurement. The lower limit of trans quantitation was 5% of total fat. The precision of this ATR method was found to be superior to that of transmission infrared official methods. Accuracy was enhanced by generating a symmetric absorption trans infrared band at 966 cm-1 on a horizontal background. This was achieved by “ratioing” the single-beam spectrum of the trans-containing fat or oil against that of a reference oil or standard having only cis double bonds. Attempts to apply this ATR-FTIR method to food matrixes with low trans fat and/or low total fat content were not satisfactory due to interfering infrared absorptions in the trans region. To overcome this interference, the method was modified by applying the standard addition technique to the ATR-FTIR determination. The modified procedure required more time, but eliminated any adverse impact on accuracy arising from interfering minor food components having absorption bands near 966 cm−1.
Biosensor Analysis of β-Lactams in Milk: Comparison with Microbiological, Immunological, and Receptor-Based Screening Methods
Authors: Gustavsson Eva , Sternesjö Åse
Published: February 2020

Two recently developed surface plasmon resonance biosensor assays for detection of β-lactams in milk were used to screen raw producer milk samples. Both assays use a β-lactam receptor protein with carboxypeptidase activity for detection. The results of the biosensor assays were compared with those of various commercial screening tests, i.e., the Delvotest SP, Penzym S, Beta-STAR, SNAP, and Parallux. The results of the 2 biosensor assays showed good agreement with those of the other screening tests. Of 195 analyzed milk samples, the results of only 5 samples differed between the assays. Additionally, 30 milk samples with both negative and positive results in the screening assays were analyzed by liquid chromatography for identification and quantification of any β-lactam residues. All screening tests showed 0% false-negative results with 15 incurred samples containing between 4.0 and 268 μg/kg penicillin G. The biosensor assays showed 27% positive results (false violatives) with 15 producer milk samples containing penicillin G concentrations between 0 and 3.6 μg/kg, i.e., below maximum residue limit. This figure varied between 27 and 53% for the other screening tests.
Suitability of Real-Time Quantitative Polymerase Chain Reaction and Enzyme-Linked Immunosorbent Assay for cry9C Detection in Mexican Corn Tortillas: Fate of DNA and Protein After Alkaline Cooking
Authors: Quirasco Maricarmen , Schoel Bernd , Plasencia Javier , Fagan John , Galvez Amanda
Published: February 2020

Alkaline-cooked corn, called nixtamal, is the basis for many traditional corn products such as tortillas, chips, and taco shells that are used widely in Mexico and Central America and in the preparation of snack foods that are consumed globally. To assess the effects of alkaline and thermal treatments on the detectability of DNA and protein for the presence of genetically modified sequences, various nixtamalized products were prepared from blends of conventional white corn containing 0.1, 1.0, and 10% transgenic corn (event CBH 351, StarLink™). Real-time quantitative polymerase chain reactions (RTQ–PCR) and immunoassays were used to determine the cry9C gene and protein, respectively, in unprocessed corn kernels, freshly prepared alkaline-cooked and ground corn (masa), masa flour, tortillas prepared from masa by heat treatment, chips prepared from damp masa dough by deep frying, and from tortillas processed at high (200°C) and low temperatures (70°C). In spite of progressive degradation of genomic DNA during processing, RTQ–PCR genetic analysis allowed detection and quantification of the cry9C gene in all products prepared from 10, 1, and 0.1% StarLink corn, except deep-fried chips containing 0.1% StarLink. Enzyme-linked immunosorbent assays readily detected <1ppm cry9C protein in all blends of unprocessed corn (10, 1, and 0.1% StarLink) as well as in nonfried tortilla and masa products. This technique was not suitable for thermally treated nixtamalized products containing <1% transgenic corn.
Resistant Starches and Health
Authors: Kendall Cyril W C , Emam Azadeh , Augustin Livia S A , Jenkins David J A
Published: February 2020

It was initially hypothesized that resistant starches, i.e., starch that enters the colon, would have protective effects on chronic colonic diseases, including reduction of colon cancer risk and in the treatment of ulcerative colitis. Recent studies have confirmed the ability of resistant starch to increase fecal bulk, increase the molar ratio of butyrate in relation to other short-chain fatty acids, and dilute fecal bile acids. However the ability of resistant starch to reduce luminal concentrations of compounds that are damaging to the colonic mucosa, including fecal ammonia, phenols, and N-nitroso compounds, still requires clear demonstration. As such, the effectiveness of resistant starch in preventing or treating colonic diseases remains to be assessed. Nevertheless, there is a fraction of what has been termed resistant (RS1) starch, which enters the colon and acts as slowly digested or lente carbohydrate in the small intestine. Foods in this class are low glycemic index and have been shown to reduce the risk of chronic disease. They have been associated with systemic physiological effects such as reduced postprandial insulin levels and higher HDL cholesterol levels. Consumption of low glycemic index foods has been shown to be related to reductions in risk of coronary heart disease and Type 2 diabetes. Type 2 diabetes has in turn been related to a higher risk of colon cancer. If carbohydrates have a protective role in colon cancer prevention this may lie partly in the systemic effects of low glycemic index foods. The colonic advantages of different carbohydrates, varying in their glycemic index and resistant starch content, therefore, remain to be determined. However, as recent positive research findings continue to mount, there is reason for optimism over the possible health advantages of those resistant starches, which are slowly digested in the small intestine.
Sample Preparation and Determination of Ginkgo Terpene Trilactones in Selected Beverage, Snack, and Dietary Supplement Products by Liquid Chromatography with Evaporative Light-Scattering Detection
Authors: Lang Qingyong , Wai Chien M , Ang Catharina Y W , Cui Yanyan , Heinze Thomas M , Mattia Antonia , Dinovi Michael
Published: February 2020

Ginkgo biloba leaf extract has been widely used in dietary supplements and more recently in some foods and beverages. Sample preparation procedures for determination of ginkgo terpene trilactones (including bilobalide and ginkgolides A, B, C, and J) in various sample matrixes were developed in this study. Ginkgo leaves and capsules were extracted with 5% KH2PO4 aqueous solution under sonication. Tea bags were extracted with boiling water, whereas drink samples were taken directly from the bottles. After filtration and the addition of NaCl to approximately 30% (w/v), the terpene trilactones in aqueous solutions were quantitatively extracted with ethyl acetate–tetrahydrofuran (4 + 1, v/v). Puff samples (a cereal-based fried snack item) were first defatted by using hexane or by using supercritical fluid extraction and then extracting under sonication with methanol–acetic acid (99 + 1, v/v). After evaporation of the organic phase, the terpene trilactones were redissolved in methanol and determined on a C18 reversed-phase column by liquid chromatography (LC) with evaporative light-scattering detection. The method of standard additions and gas chromatography with flame ionization detection were used for method validation. For most samples, the relative standard deviation was <10%. The identities of target compounds in ginkgo leaves and drink samples were confirmed by LC/electrospray ionization–tandem mass spectrometry.
The Modular Analytical Procedure and Validation Approach and the Units of Measurement for Genetically Modified Materials in Foods and Feeds
Authors: Holst-Jensen Arne , Berdal Knut G
Published: February 2020

Food and feed analysts are confronted with a number of common problems, irrespective of the analytical target. The analytical procedure can be described as a series of successive steps: sampling, sample processing, analyte extraction, and ending, finally, in interpretation of an analytical result produced with, e.g., real-time polymerase chain reaction. The final analytical result is dependent on proper method selection and execution and is only valid if valid methods (modules) are used throughout the analytical procedure. The final step is easy to validate—the measurement uncertainty added from this step is relatively limited and can be estimated with a high degree of precision. In contrast, the front-end sampling and processing steps have not evolved much, and the corresponding methods are rarely or never experimentally validated according to internationally harmonized protocols. In this paper, we outlined a strategy for modular validation of the entire analytical procedure, using an upstream validation approach, illustrated with methods for genetically modified materials that may partially apply also to other areas of food and feed analyses. We have also discussed some implications and consequences of this approach in relation to reference materials, measurement units, and thresholds for labelling and enforcement, and for application of the validated methods (modules) in routine food and feed analysis.
Evaluation of Sampling Plans to Detect Cry9C Protein in Corn Flour and Meal
Authors: Whitaker Thomas B , Trucksess Mary W , Giesbrecht Francis G , Slate Andrew B , Thomas Francis S
Published: February 2020

StarLink is a genetically modified corn that produces an insecticidal protein, Cry9C. Studies were conducted to determine the variability and Cry9C distribution among sample test results when Cry9C protein was estimated in a bulk lot of corn flour and meal. Emphasis was placed on measuring sampling and analytical variances associated with each step of the test procedure used to measure Cry9C in corn flour and meal. Two commercially available enzyme-linked immunosorbent assay kits were used: one for the determination of Cry9C protein concentration and the other for % StarLink seed. The sampling and analytical variances associated with each step of the Cry9C test procedures were determined for flour and meal. Variances were found to be functions of Cry9C concentration, and regression equations were developed to describe the relationships. Because of the larger particle size, sampling variability associated with cornmeal was about double that for corn flour. For cornmeal, the sampling variance accounted for 92.6% of the total testing variability. The observed sampling and analytical distributions were compared with the Normal distribution. In almost all comparisons, the null hypothesis that the Cry9C protein values were sampled from a Normal distribution could not be rejected at 95% confidence limits. The Normal distribution and the variance estimates were used to evaluate the performance of several Cry9C protein sampling plans for corn flour and meal. Operating characteristic curves were developed and used to demonstrate the effect of increasing sample size on reducing false positives (seller's risk) and false negatives (buyer's risk).
Solid-Phase Extraction and Cleanup Procedures for Determination of Acrylamide in Fried Potato Products by Liquid Chromatography/Mass Spectrometry
Authors: Young Michael S , Jenkins Kevin M , Mallet Claude R
Published: February 2020

In response to recent discoveries of acrylamide in heated foods, a solid-phase extraction and cleanup protocol was developed for the determination of acrylamide in fried or baked potato samples by liquid chromatography/mass spectrometry (LC/MS). The analyte was extracted from the matrix by using 2M NaCl, and an aliquot of the initial extract was loaded onto a reversed-phase cartridge. After the analyte was eluted from the cartridge, the eluate was cleaned up on a mixed-mode cation-exchange cartridge. The eluate was then evaporated, and the residue was reconstituted in mobile phase before LC/MS analysis. Recoveries, based on the recovery of an added internal standard, ranged from 96 to 101% with relative standard deviations (RSDs) of 5–11%. The response was linear for a concentration range of 100–2000 ng/g with a coefficient of determination (R2)of 0.992 (n = 25). An interday study showed good accuracy and precision of the method over a 3-day period with a recovery of 98% and an RSD of 9.5% (n = 15). The analyses of 6 potato chip samples showed concentrations of incurred acrylamide ranging from 260 to 1500 ng/g.
Determination of Thallium in Potassium Chloride and Electrolyte Replenishers by Electrothermal Atomic Absorption Spectrometry
Authors: Nukatsuka Isoshi , Horiguchi Ryo , Seitoh Hiroyuki , Ohzeki Kunio , Miyashita Fumihide
Published: February 2020

Thallium in potassium chloride and electrolyte replenishers was determined by electrothermal atomic absorption spectrometry (ETAAS) with direct injection of a resin suspension. Thallium(III) was extracted on fine particles of a cellulose nitrate resin (CNR) from dilute HCl (pH 1.6) in the presence of ammonium pyrrolidine-1- carbodithioate. The CNR particles were collected on a membrane filter by filtration under suction, suspended in 1.0 mL 10mM HNO3, and then delivered directly to ETAAS as the suspension. The effects of chloride ions were thoroughly investigated. The results showed that the addition of 0.5mM NaCl to the suspension (10mM HNO3) was recommended, after CNR and a membrane filter holding the CNR were washed thoroughly with 0.025M HCl, to eliminate interference from chloride ions. No chemical modifier was required. Extraction from the solution containing up to 2M chloride ion was allowable. The proposed method gave a concentration factor of 50 for a 50 mL sample volume. The detection limit (3σ, n = 5) was 1 ng (20 pg/mL). The relative standard deviation was 4.9% (n = 5) at 30 ng level of thallium. The content of thallium in potassium chloride was 15.7–32.8 ng/g, and in electrolyte replenishers was 0.18–4.16 ng/mL.
Ultraviolet Derivatization of Steroidal Saponin in Garlic and Commercial Garlic Products as p-Nitrobenzoate for Liquid Chromatographic Determination
Authors: Mochizuki Emiko , Yamamoto Takao , Mimaki Yoshihiro , Sashida Yutaka
Published: February 2020

A method is described for determination of the steroidal saponin, eruboside B, originating in garlic and garlic products as the p-nitrobenzoyl chloride (PNBC) derivative by reversed-phase liquid chromatography (with ultraviolet detection at 260 nm. Proto-eruboside B was extracted from garlic (Allium sativum L.); subjected to solid-phase extraction (SPE) with a C18 cartridge, Florisil column chromatography, and silica gel column chromatography; and then enzymatically converted to eruboside B, which was applied as an external standard. Steroidal saponins in garlic and commercial garlic products were extracted with methanol and purified by SPE cartridges, followed by enzymatic treatment. A frostanol saponin such as proto-eruboside B is enzymatically transformed to a spirostanol saponin, eruboside B. After the derivatization with PNBC, the saponin derivative was chromatographed on a C8 column with a gradient elution of (A) 80% aqueous acetonitrile and (B) 100% acetonitrile. The detection limit of the developed method was 1 μg/g for the samples. The method was applied to the analysis of garlic and and garlic health food products available in Japan.
Method for the Determination of β-Carotene in Supplements and Raw Materials by Reversed-Phase Liquid Chromatography: Single Laboratory Validation
Authors: Schierle Joseph , Pietsch Bernd , Ceresa Alan , Fizet Christian , Waysek Edward H
Published: February 2020

A single laboratory validation (SLV) study was conducted for a liquid chromatography (LC) method for the determination of total and all-trans-β-carotene in a variety of dietary supplements, including multivitamin tablets, softgels, capsules, and beadlet raw materials. Extraction variants were developed for the different types of supplements tested based upon the supplement type and level of β-carotene. Water dispersible formulations such as powders, emulsions, tablets, and capsules were enzymatically digested with protease and extracted with dichloromethane–ethanol. Oily suspensions were directly dissolved in dichloromethane–ethanol. After appropriate dilution or concentration, the extracts were chromatographed by using either a reversed-phase C18 column or, in products containing high amounts of α-carotene, a reversed-phase C30 column. The LC systems provided linear responses in the range of 0.1–50 μg β-carotene/mL. The main geometrical isomers of β-carotene (all-trans, 9-cis, 13-cis, and 15-cis) were well separated from each other and from other carotenoids such as α-carotene, cryptoxanthin, lutein, lycopene, and zeaxanthin. Duplicate determinations of total β-carotene performed by 2 technicians in 8 different test materials on 5 different days resulted in relative standard deviations of 1.2–4.4%. Recoveries determined for supplements and beadlet raw material spiked with β-carotene levels of 10 μg to 100 mg/test portion and 0.2–40%, respectively, ranged from 97.5 to 102.1%. On the basis of the accuracy, precision, and recovery results from the SLV study, the method is suggested for a collaborative study on the determination of total and all-trans-β-carotene in dietary supplements.
Development and Validation of a Liquid Chromatographic Method for Fexofenadine Hydrochloride in Capsules
Authors: Breier Ana R , Paim Clésio S , Menegola Júulia , Steppe Martin , Schapoval Elfrides E S , Schapoval Elfrides E S
Published: February 2020

This paper describes the development and validation of a new, simple, fast, and sensitive liquid chromatographic method for the determination of the antihistamine fexofenadine. Although widely used in the treatment of allergic diseases, fexofenadine is not listed in any pharmacopeia, and there are few methods in the literature for its quantitation in pharmaceutical dosage forms. In this work, a LiChrospher® 100 RP-18 (250 × 4.0 mm, 5 μm) column was used as the stationary phase, and acetonitrile–5mM ammonium acetate buffer (50 + 50, v/v) at pH 3.2 was the mobile phase. Through the evaluation of the analytical parameters, it was shown that the method is linear (r = 0.9999) at concentrations ranging from 20.0 to 80.0 μg/mL, precise (intraday relative standard deviation [RSD] values = 0.85, 0.40, and 0.81%; interday RSD = 0.77%), accurate (mean recovery = 99.05%), specific, and robust. The detection and quantitation limits are 0.3409 and 1.033 μg/mL, respectively. These low values show the good sensitivity of the proposed method.
Enzymatic, Spectrophotometric Determination of Glucose, Fructose, Sucrose, and Inulin/Oligofructose in Foods
Authors: Steegmans Monique , Iliaens Saskia , Hoebregs Hubert
Published: February 2020

A fast, simple, and accurate method, using only standard laboratory equipment, was developed for the quantification of glucose, fructose, sucrose, and inulin/oligofructose in different food matrixes. Samples were extracted using boiling water and hydrolyzed with sucrase and fructanase. Sugars were determined in the initial extract and in both hydrolysates using an enzymatic, spectrophotometric kit for glucose and fructose determination with hexokinase, glucose-6-phosphate dehydrogenase, and phosphoglucose isomerase. Calculations of sucrose and inulin/oligofructose were based only on fructose measurement. Glucose results of the hydrolysates were not used for inulin/oligofructose calculations because of possible interference. Released glucose by the hydrolysis of maltose or by possible partial hydrolysis of other compounds like maltodextrines, starch, lactose, or maltitol could interfere in the measurement of the sucrase and the fructanase hydrolysates. To validate the method, a wide range of different food matrixes and different amounts of inulin/oligofructose (1–54%) were analyzed. Mean recovery ± relative standard deviation (RSD) for inulin or oligofructose was 96.0 ± 5.3%. The RSDr for inulin/oligofructose measured on 35 food samples, analyzed in duplicate, was 5.9%. Accuracy and precision of the method were less for samples with large concentrations of sucrose, maltose, maltodextrines, or s tarch (ratio to inulin/oligofructose >4 to 1). Precision and accuracy were comparable with those of the ion exchange chromatographic method AOAC 997.08 and the enzymatic, spectrophotometric method AOAC 999.03. In contrast to 999.03, this method allows the accurate quantification of both GFn and Fn forms.
Determination of Sulfonamide Residues in the Tissues of Food Animals Using Automated Precolumn Derivatization and Liquid Chromatography with Fluorescence Detection
Authors: Salisbury Craig D C , Sweet Jason C , Munro Roger
Published: February 2020

A liquid chromatographic method for the determination of sulfachloropyridazine, sulfadiazine, sulfadimethoxine, sulfadoxine, sulfaethoxypyridazine, sulfamethazine, sulfaquinoxaline, and sulfathiazole residues in the muscle, liver, and kidney of food animals using sulfapyridine as internal standard is reported. Tissues are extracted using a modified version of AOAC Official Method 983.31 (Sulfonamide Residues in Animal Tissues). The sample extract is reconstituted in pH 3.0 buffer–acetonitrile (60 + 40) and filtered into an autosampler vial. Using a programmable autosampler of a liquid chromatograph, a portion of the sample is derivatized precolumn with fluorescamine. The sulfonamide derivatives are separated by liquid chromatography using a C18 column with a mobile phase of 0.02M phosphoric acid–acetonitrile (60.5 + 39.5) and detected by fluorescence (excitation, 405 nm; emission, 495 nm). The method was applied to swine and cattle muscle, liver, and kidney; sheep and horse muscle and kidney; and chicken muscle and liver. The mean values for samples fortified with sulfonamides at levels between 0.05 and 0.2 μg/g agreed within 96–99% of spiked levels, with coefficients of variation ranging from 4–10%. The limit of detection (LOD) for all sulfonamides was 0.01 μg/g, with the exception of sulfaquinoxaline, for which the LOD was 0.015 μg/g.
Validation of the Anti-Factor Xa Assay for the Potency Assessment of Enoxaparin in Pharmaceutical Formulations
Authors: Dalmora Sérgio Luiz , Júnior Liberato Brum , Schmidt Cleber Alberto , Vaccari Silvana Ferreira , Oliveira Paulo Renato , Codevilla Cristiane Franco
Published: February 2020

Enoxaparin is a low-molecular weight heparin used clinically for the prevention and treatment of venous and arterial thrombosis. An anti-factor Xa assay was used to evaluate the potency of the final drug preparation. Method validation investigated parameters such as the range, linearity (r2 = 0.9971), precision, accuracy, and robustness; the biological assay incorporated a chromogenic endpoint and detection at 405 nm. The method yielded good results with a quantitation limit of 0.037 IU/mL and a detection limit of 0.011 IU/mL. The results demonstrated the validity of the anti-factor Xa assay for the determination of enoxaparin.