bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Total Nitrogen in Urine by Pyrochemiluminescence: Collaborative Study
Authors: Boehm Kristi A , Ross P Frank
Published: February 2020

Twelve collaborating laboratories analyzed 5 blind duplicate samples of human urine for total nitrogen using a pyrochemiluminescence method. The nitrogen content ranged from low (650 mg/L) to high levels (8800 mg/L) in urine samples of people under moderate to severe stress. In addition to test samples, collaborators also received a certified standard (sodium nitrite in water) as an external control. The pyrochemiluminescence assay was performed on urine samples diluted in water within a range of 1:50 to 1:100. The method detects total nitrogen by reaction of the product of high temperature oxidative pyrolysis and ozone. Repeatability standard deviation values (RDSr) ranged from 1.49 to 3.91% and reproducibility standard deviation values (RSDR) ranged from 3.66 to 9.57%. The average recovery of total nitrogen was 99.9%. The pyrochemiluminescence method for determination of total nitrogen in urine was adopted first action by AOAC INTERNATIONAL.
Determination of Residues of Flumequine and Nalidixic, Oxolinic, and Piromidic Acids in Catfish by Liquid Chromatography with Fluorescence and UV Detection
Authors: Munns Robert K , Turnipseed Sherri B , Pfenning Allen P , Roybal José E , Holland David C , Long Austin R , Plakas Steven M
Published: February 2020

A liquid chromatographic (LC) method is described for determining residues of flumequine (FLU) and nalidixic (NAL), oxolinic (OXO), and piromidic (PIR) acids in catfish muscle. The identities of 3 of these residues are confirmed by gas chromatography–mass spectrometry (GC–MS). The extraction and cleanup procedures are the same for both determination and identification. Analyte isolation involves homogenizing the tissue with acetone, defatting the acetone extract with hexane, and extracting the compounds into chloroform. The extract is further purified by first partitioning into base and subsequently back-extracting into chloroform after acidifying the aqueous phase. After the solvent is evaporated, the residue is dissolved in mobile phase, and the analytes are determined by LC with fluorescence detection, excitation at 325 nm and emission at 365 nm. Catfish muscle was fortified with each quinolone at 5,10,20,40, and 80 ng/g. Overall average recoveries were 83–94%, with relative standard deviations (RSDs) of 5–7%. The method was evaluated also by a second analyst, who determined 4 quinolones added in combination. Average recoveries of quinolones from catfish fortified at 5,10, and 20 ng/g were 78–90%, with RSDs of 3–6%. The presence in catfish muscle of incurred OXO, FLU, and NAL at the 10 ng/g level was confirmed by analyzing the decarboxylated quinolones by GC–MS. The relative abundances of all 5 major ions for OXO, FLU, and NAL were within 10% of those observed in spectra of standard compounds decarboxylated by the same method.
Survey of Trihalomethanes and Other Volatile Chemical Contaminants in Processed Foods by Purge-and-Trap Capillary Gas Chromatography with Mass Selective Detection
Authors: Mcneal Timothy P , Hollifield Henry C , Diachenko Gregory W
Published: February 2020

A limited number of soft drinks, juices, beers, and waters from processed vegetables were analyzed for trihalomethanes (THMs), benzene, and toluene by a modified Environmental Protection Agency (EPA) Method 524.2. The THMs, which include chloroform, bromodichloromethane, dibromochloromethane, and bromoform, are reaction by-products of water disinfection by chlorination. EPA Method 524.2 is a purge-and-trap capillary gas chromatographic method based on mass spectrometric detection which identifies and simultaneously measures purgeable volatile organic compounds in drinking water. Chloroform was present at concentrations ranging from none detected to 94 ng/g in the 44 foods analyzed. Bromoform was not found in any of the products at a detection limit of 0.1 ng/g. Residue levels of the other THMs ranged from none detected to highs of 12 and 2 ng/g for bromodichloromethane and drbromochloromethane, respectively. Benzene residues were typically <5 ng/g, except for 7 and 9 ng/g in 2 foods. Toluene residues were typically ≤3 ng/g except for 23,29, and 75 ng/g in 3 canned foods.
Determination of Malachite Green and Its Metabolite, Leucomalachite Green, in Catfish (Ictalurus punctatus) Tissue by Liquid Chromatography with Visible Detection
Authors: Roybal José E , Pfenning Allen P , Munns Robert K , Holland David C , Hurlbut Jeffrey A , Long Austin R
Published: February 2020

To determine residues of malachite green (MG) and its metabolite, leucomalachite green (LMG), in catfish tissue, analytes are extracted with acetonitrilebuffer and the extract is partitioned into methylene chloride. Final cleanup and isolation are performed on neutral alumina solid-phase extraction (SPE) and propylsulfonic acid cation-exchange SPE columns before analysis by liquid chromatography with visible detection. PbO2 postcolumn oxidation is performed by isocratic elution with a buffered mobile phase from a cyano column. Recoveries and relative standard deviations (RSDs) from fortified catfish tissues were 72.9% (RSD, 1.92%; 23 ppb), 75.5% (RSD, 6.85%; 11 ppb), and 69.6% (RSD, 6.93%; 5.7 ppb) for MG and 87.4% (RSD, 2.92%; 21 ppb), 88.1% (RSD, 5.94%; 10 ppb), and 82.6% (RSD, 11.5%; 5.3 ppb) for LMG. The method was applied to MG-incurred catfish at depuration times of 0,2,4,8, and 24 h. Average levels of residual MG and LMG in the 24 h depuration catfish tissue were 73.4 and 289 ppb, respectively.
Detection of Sodium Channel Toxins: Directed Cytotoxicity Assays of Purified Ciguatoxins, Brevetoxins, Saxitoxins, and Seafood Extracts
Authors: Manger Ron L , Leja Linda S , Lee Sue Y , Hungerford Jem M , Hokama Yoshttsugi , Dickey Robert W , Granade H Ray , Lewis Richard , Yasumoto Takeshi , Wekell Marleen M
Published: February 2020

Neuroblastoma cells in culture were used to detect sodium channel-specific marine toxins based on an end-point determination of mitochondrial dehydrogenase activity. The assay responds in a dose-dependent manner to ciguatoxins, brevetoxins, and saxitoxins, and delineates the toxic activity as either sodium channel enhancing or sodium channel blocking. The assay responds rapidly to sodium channel activating toxins, allowing dose dependent detection in 4 to 6 h. Brevetoxins can be detected at 250 pg, and purified ciguatoxins are detected in the low picogram and subpicogram levels. The results obtained from cell bioassay of ciguatoxic finfish extracts correlates with those obtained from mouse bioassays. Sodium channel blocking toxins can also be detected with an approximate sensitivity of 20 pg in 24 to 48 h. This cell-based technique is simple, sensitive, demonstrates potential as an alternative to animal testing for sodium channel activating and blocking toxins, and can be automated.
Radioimmunoassay for PbTx-2-Type Brevetoxins: Epitope Specificity of Two Anti-PbTx Sera
Authors: Poli Mark A , Rein Kathleen S , Baden Daniel G
Published: February 2020

Antiserum against PbTx-2-type brevetoxins was produced by immunizing rabbits with a PbTx-2–bovine serum albumin (BSA) conjugate. This serum had a higher affinity, but lower titer, than our current goat serum. Using 4 natural brevetoxins and 6 synthetic derivatives as competitors in our brevetoxin radioimmunoassay, we determined the epitope specificity of both sera. Modification of the backbone structure at C-42 on the K-ring had little or no effect on the antigen-binding capability of either serum. Reduction of the double bond between C-2 and C-3 on the A-ring by reduction of the lactone decreased binding 500 to 750-fold. Epoxidation of the double bond between C-27 and C-28 on the H-ring did not affect binding, which suggested that the goat serum is specific for the A-ring region of the brevetoxin backbone. In contrast, modifying the A-ring had no effect on rabbit serum binding. However, epoxidation of the H-ring decreased binding 5 to 20-fold, which suggested that the rabbit antiserum is specific for the H-ring region of the molecule. These results suggest that assays utilizing only one antibody may not adequately detect toxin metabolites if molecules are altered in the critical region of antibody recognition.
Determinations of Marine Toxins in Foods
Authors: Yasumoto Takeshi , Fukui Masakazu , Sasaki Katsunori , Sugiyama Kiminori
Published: February 2020

Prospects of new analytical methods for determining marine toxins in foods are described. The methods discussed include fluorometric liquid chromatography, cytotoxicity assays, channel binding assays, and enzyme-immunoassays. Emphasis was laid on assay methods for ciguatoxins and diarrhetric shellfish toxins.
Microbiological Plate Assay for Determination of Tilmicosin in Bovine Serum
Authors: Coleman Mark R , Peloso James S , Moran John W
Published: February 2020

A microbiological agar plate assay is described for determination of tilmicosin in bovine blood serum. The serum or serum dilution is added directly to wells cut in the agar plates. Tilmicosin activity is determined by measuring the zone of bacterial growth inhibition in agar medium inoculated with Micrococcus luteus, ATCC 9341. The assay was validated by evaluating the following parameters: accuracy, precision, linearity, parallelism, ruggedness, storage stability, and relative activity of isomers. Accuracy was evaluated with freshly collected bovine serum and with commercially available sera. Recoveries ranged from 93.4 to 97.5% across a fortification range of 0.08 to 1.28 μg/mL. Precision was estimated over a 6-day period with serum obtained from a tilmicosin-treated animal. Relative standard deviations were 0.63 to 3.13% within day and 5.23% across 6 days. Standard curves were linear with little variation in slope. No parallelism was observed between tilmicosin in serum and tilmicosin in buffered saline. The limit of detection was estimated to be 0.05 μg/mL, and the validated limit of quantitation was 0.08 μg/mL. Ruggedness was evaluated with different lots of antibiotic medium, different lots of sera, and different analysts. These variables did not affect method performance. Analyses of tilmicosin in frozen sera demonstrated that tilmicosin is stable for up to 16 days when stored at −20°C. A comparison of the relative microbiological activities of the purified cis and trans isomers of tilmicosin to that of the reference standard indicated no differences in microbiological activities, and showed a parallel response among the 3. The validation data demonstrate that this method is a rugged, reliable, and simple assay for tilmicosin in serum.
Liquid Chromatographic Determination of Fluorescent Derivatives of Six Sulfonamides in Bovine Serum and Milk
Authors: Tsai Chin-En , Kondo Fusao
Published: February 2020

A rapid and sensitive liquid chromatographic (LC) method with fluorometric detection was developed to detect sulfadiazine, sulfathiazole, sulfamethazine, sulfamonomethoxine, sulfamethoxazole, and sulfadimethoxine residues in bovine serum and milk. p-Aminobenzoic acid (PABA) was added as an internal standard. The sulfonamides were extracted from samples and derivatized with fluorescamine, and 50 μL was injected into a NovaPak C18 LC column and eluted with acetonitrile– 10 mM potassium phosphate (30 + 70, v/v). The sulfonamides were detected fluorometrically (excitation, 390 nm; emission, 475 nm), and their retention times ranged from 6.2 to 16.5 min without interference from coextractives. The detection limit for standard sulfonamide solution was 0.1 ng/mL; the calibration curves were linear between 1 and 100 ng/mL in the presence of PABA as internal standard. Recovery rates of sulfonamides from spiked samples (1 and 10 ppb) were 95.4–107.2 and 81.4–89.6% for serum and 80.7–91.1 and 62.6–84.1% for milk, respectively.
Determination of Soluble and Insoluble Dietary Fiber in Psyllium-Containing Cereal Products
Authors: Lee Sungsoo C , Rodriguez Flo , Storey Maureen , Farmakalidis Efi , Prosky Leon
Published: February 2020

A method for soluble and insoluble dietary fiber determinations was developed for psyllium-containing food products, which are highly viscous in aqueous solutions. The assay is based on a modification of the AOAC soluble and insoluble dietary fiber method (991.43), which was recommended for nutrition labeling in the final U.S. food labeling regulations. We found that method 991.43 and other existing dietary fiber methods could not be applied to psyllium food products, which exhibit high viscosity in aqueous solutions, because highly viscous solutions could not be filtered easily. In this study, we modified AOAC method 991.43 to accommodate the filtration process of viscous sample solutions. Sonication followed by highspeed centrifugation was used before filtration. The principles of the method are similar to those for AOAC method 991.43, including the use of the same 3 enzymes (heat-stable α-amylase, protease, and amyloglucosidase) as well as similar enzyme incubation conditions. The modification using sonication and high-speed centrifugation did not alter the method performance for analytically normal products such as wheat bran, oat bran, and soy fiber. Yet, the modification allowed the separation of soluble dietary fiber fractions from insoluble fractions for psyllium products with satisfactory precision. This method for psyllium dietary fiber determinations may be applied to other food products that exhibit high viscosity in aqueous solutions.
Multiresidue Method for the Chromatographic Determination of Triazine Herbicides and Their Metabolites in Raw Agricultural Products
Authors: Pardue John R
Published: February 2020

A method is described for the determination of 19 triazine herbicides and 4 metabolites in 6 agricultural products that represent diverse matrixes. In addition, a modification of this method to determine the more water-soluble metabolite, de-sethyldesisopropylatrazine, is described. In both these procedures, residues are extracted with methanol, and the product coextractives are removed using solvent partition and cation-exchange solid-phase extraction chromatography. A nitrogen phosphorus detector and DB-17 megabore column are used for the temperature-programmed chromatographic determination of samples fortified at 0.02–1.0 ppm levels. Average recoveries ranged from 81.1 to 106.2% for the parent herbicides and from 59.6 to 87.5% for the metabolites on all crops. An average recovery of 101.1% was obtained for de-sethyldesisopropylatrazine.
Microwave Digestion–Inductively Coupled Plasma Atomic Emission Spectrometric Determination of Boron in Raw Noodles
Authors: Ziaziaris John , Kacprzak Jurgen L
Published: February 2020

Samples of raw noodles in a mixture of nitric acid and hydrogen peroxide were microwave digested in sealed tetrafluoromethaxil (PTFE TFM) vessels. The digests were diluted to volume with distilled water and quantitated by inductively coupled plasma atomic emission spectroscopy (ICP–AES). The recoveries of boron for spikes of 2.5, 250, and 500 μg were 88,101, and 102%, respectively. The quantitation limit was estimated to be 1.5 mg B/kg. The method is rapid and ideally suited to large numbers of samples.
Improved Determination of Chlorite and Chlorate in Rinse Water from Carrots and Green Beans by Liquid Chromatography and Amperometric and Conductivity Detection
Authors: Beitler Mark K , Chin Henry B
Published: February 2020

A method is presented for determining chlorite and chlorate in the presence of interfering organic compounds in rinse water from vegetables. Rinse water from cut raw carrots and green beans was fortified separately with chlorite and chlorate, filtered (0.45 μm), and analyzed by liquid chromatography with amperometric and conductivity detection. Detection limits for chlorite and chlorate in carrot rinse water were 17 and 50 ppb, respectively. Average recoveries from rinse water were 95% for chlorite in a 0.084–1.00 ppm range and 90% for chlorate in a 0.078–1.00 ppm range.
Evaluation of Sampling Plans Used in the United States, United Kingdom, and The Netherlands To Test Raw Shelled Peanuts for Aflatoxin
Authors: Whttaker Thomas B , Springer Janet , Defize Peter R , Dekoe Willem J , Coker Ray
Published: February 2020

The United States is a large producer and exporter of peanuts. The United Kingdom and The Netherlands are major importers of U.S. peanuts. Each country has a different guideline or legal limit for peanut products containing aflatoxin. Peanuts are tested for aflatoxin in each country by using specifically designed aflatoxin sampling plans to determine if the aflatoxin concentration in a lot of raw shelled peanuts is less than the guideline or legal limit. For raw shelled peanuts, the U.S. plan has the highest sample acceptance limit of 15 ng total aflatoxin/g, the UK plan has a sample acceptance limit of 10 ng total aflatoxin/g, and the Dutch Code of Practice (called the Dutch plan) has the lowest sample acceptance limit at 3 ng aflatoxin B1/g. The U.S. plan uses a maximum of 3 sampling units, each weighing 21.8 kg; the UK plan uses a single sampling unit of 10 kg; and the Dutch plan uses 4 sampling units, each weighing 7.5 kg. The sampling variance is lowest for the U.S. plan and highest for the Dutch plan. The sample preparation variance is lowest for both the Dutch and UK plans and highest for the U.S. plan, primarily because of the mill type used to comminute the kernels in the sample. For a given distribution among lot concentrations, the U.S. plan accepts the greatest number of lots and the Dutch plan rejects the greatest number of lots. The average aflatoxin concentration among accepted lots is highest for the U.S. plan and lowest for the Dutch plan. The U.S. plan accepts the greatest number of good lots, whereas the Dutch plan rejects the greatest number of bad lots. The Dutch plan rejects the greatest number of good lots, whereas the U.S. plan rejects the lowest number of good lots. The Dutch plan accepts the lowest number of bad lots, whereas the UK plan accepts the greatest number of bad lots.
Immunoassay of Pesticides: An Update
Authors: Kaufman Bennett M , Clower Marion
Published: February 2020

Measurement of levels of pesticide residues in foods and crops most often requires extensive cleanup and instrumental techniques such as gas chromatography. Immunoassay measurement techniques, on the other hand, may be used directly on the test portion or require only minimal cleanup. Further refinements of the common antibody–enzyme-based solid-phase assays, such as use of coated magnetic particles, antibody-coated crystals, and continuous-flow devices, have extended the measurement range and applicability of these assays. Likewise, new immunoassays for pesticides have been developed, and existing assays have been refined, optimized, and more completely characterized and validated. In addition to their ability to accurately and reliably measure amounts of residues present in food and crops, immunoassays can be readily used as rapid screening methods for contaminants in field samples. We have previously reviewed much of the work in the area of pesticide immunoassay; this report updates previous information and discusses some new immunoassay techniques.
Statistical Analysis of Spectrometric Procedures for Determination of Fe(III) and V(V) with Desferrioxamine B
Authors: Luterotti Svjetlana , Grdinic Vladimir
Published: February 2020

For statistical evaluation of VIS-spectrometric procedures for determination of Fe(III) and V(V), with desferrioxamine B as a chromogenic agent, the slightly modified Gottschalk concept is used and found to be appropriate. Favorable metrological characteristics of both analytical procedures make them likely candidates for standard quantitative protocols.
Determination of Flunixin in Milk by Liquid Chromatography with Confirmation by Gas Chromatography/Mass Spectrometry and Selected Ion Monitoring
Authors: Rupp Heidi S , Holland David C , Munns Robert K , Turnipseed Sherri B , Long Austin R
Published: February 2020

A liquid chromatographic (LC) method was developed for the determination of flunixin (FNX) in raw bovine milk. The milk was acidified and mixed with silica gel, and the mixture was packed into a chromatographic column. The column was defatted with water-saturated dichloromethane–hexane (30 + 70, v/v), and the analyte was eluted with EtOAc. The EtOAc extract was washed with water at pH 3.5, the water was discarded, and the EtOAc layer was then extracted with 0.1 M NaOH. The aqueous layer was drained, passed through a primed C18 solid-phase extraction (SPE) column, and eluted with EtOAc. The EtOAc layer was dried under N2, taken up in a solution of MeOH–(5 mM tetrabutylammonium [TBA]–H2PO4 + 2 mM NaOH) (50 + 50), sonicated, and filtered. FNX was determined by LC using a C18 column (ODS Hypersil), a mobile phase mixture of 58% A (MeOH) and 42% B (5 mM TBA–H2PO4 + 2 mM NaOH), and a diode-array ultraviolet detector at 285 nm. FNX was determined in raw milk at 5 spiking levels (5,10,20,40, and 80 ng drug/mL milk). Absolute recoveries ranged from 69.6 to 74.4%, and relative standard deviations ranged from 1.1 to 6.9%. The limit of quantitation was 1.7 ng drug/mL milk. A lactating cow was dosed intravenously (2.2 mg/kg) with flunixin meglumine (Banamine) to generate incurred milk residues. FNX residues ranged from 7.34 ng/mL at 16 h postdose to 1.74 ng/mL at 24 h postdose. Both levels were obtained with additional β-glucuronidase treatment (almost no incurred drug was detected at these low levels without the enzyme treatment). The presence of FNX in incurred milk was confirmed by gas chromatography/mass spectrometry with selected ion monitoring.
Multiresidue Determination of Pesticides in Fruit and Vegetables by Gas Chromatography–Mass-Selective Detection and Liquid Chromatography with Fluorescence Detection
Authors: Fillion Julbe , Hemdle Ralph , Lacrolx Mario , Selwyn Jennifer
Published: February 2020

A method is described for determining 199 pesticides in fruit and vegetables. Residues are extracted from samples with acetonitrile, and coextractives are removed with a miniaturized charcoal–Celite column cleanup. Analysis is performed by gas chromatography with mass-selective detection in selective-ion monitoring mode. Two injections per sample are required to cover all compounds. Positive analytes are confirmed by retention time and ion ratios. Carbamates are analyzed by liquid chromatography with postcolumn reaction and fluorescence detection. Recovery data were obtained by fortifying 3 matrixes (pears, carrots, and bananas) at 0.1–0.5 ppm. In addition, the method demonstrated acceptable performance for analysis of other crops such as apple, strawberry, orange, pineapple, asparagus, beet, cucumber, tomato, pepper, squash, green peas, potato, and sweet potato. Limits of detection ranged from 0.02 to 0.2 ppm depending on the compound.
Market Basket and Duplicate Portion Estimation of Dietary Intakes of Cadmium, Mercury, Arsenic, Copper, Manganese, and Zinc by Japanese Adults
Authors: Tsuda Taizo , Inoue Tomohiro , Kojima Mihoko , Aoki Shigeru
Published: February 2020

Daily intakes of selected metals from meals in Shiga Prefecture (Japan) were investigated by the duplicate portion method and market basket method. In 1991 and 1992, daily intakes of metals by women, determined by the duplicate portion method, were, respectively, 37 and 27 μg for Cd, 4.3 and 3.5 μg for Hg, 260 and 210 μg for As, 1200 and 1200 (ig for Cu, 4700 and 3600 (ig for Mn, and 8000 and 7200 μg for Zn. Those determined by the market basket method were, respectively, 32 and 35 μg for Cd, 4.3 and 9.9 μg for Hg, 160 and 280 μg for As, 1100 and 980 μg for Cu, 3600 and 4700 μg for Mn, and 8700 and 8500 fig for Zn. No wide differences between the 2 methods were found, except for Hg data in 1992. Daily intakes of Cd and Hg in Shiga Prefecture were lower than the provisional tolerable daily intakes of 57-72 μg for Cd and 43 μg for Hg, proposed by the Food and Agricultural Organization and the World Health Organization.
Determination of Reserpine and Chlorothiazide in Commercial Tablets by Liquid Chromatography with Fluorescence and UV Absorbance Detectors in Series
Authors: Cieri Ugo R
Published: February 2020

A procedure is presented for determination of reserpine and chlorothiazide in commercial tablets by liquid chromatography (LC). Powdered sample, equivalent to the weight of one tablet, is dissolved in 10.0 mL dimethyl sulfoxide, the mixture is diluted to 100.0 mL with methanol, and the solution is filtered; 10 mL of the filtrate is then diluted to 100.0 mL with methanol. The standard solution is prepared in the same solvent mixture and contains the 2 ingredients in approximately the same quantities as in the diluted sample solution. For LC, a 7.5 cm long normal-phase column is used; mobile phase consists of methanol containing a small volume of an aqueous solution of 1-pentanesulfonic acid, sodium salt. Two detectors are arranged in series: a fluorescence detector set at 280 nm excitation and 360 nm emission quantitates reserpine and a UV absorbance detector set at 300 nm determines chlorothiazide. Several synthetic mixtures containing the 2 ingredients in amounts ranging from 80 to 120% of quantities declared in commercial tablets were analyzed by the proposed method. Two samples of commercial tablets were also analyzed; for each sample, 5 determinations were made on a ground composite of 20 tablets; 10 individual tablets were also analyzed. The composites were also analyzed by the current U.S. Pharmacopeia method for this product.
Determination of Thiabendazole Residues in White and Sweet Potatoes by Liquid Chromatography with Fluorescence Detection
Authors: Arenas Rene V , Rahman Hafizur , Johnson Nelson A
Published: February 2020

A liquid chromatographic (LC) method was developed for determination of thiabendazole (TBZ) residues in or on whole, unwashed white potatoes (Solarium tuberosum) and sweet potatoes (Ipomoea batatas). TBZ is extracted from the potato homogenate with ethyl acetate and the extract purified and concentrated on a cation-exchange, solidphase extraction column. The extract is analyzed for TBZ residues by column LC with a cation-exchange column and fluorescence detection. Recoveries of TBZ from whole white potatoes fortified with TBZ at 0.05–20 ppm and from whole sweet potatoes fortified with TBZ at 0.005–0.1 ppm averaged 100 and 94%, respectively. The method is also applicable for quantitation of TBZ residues in white potato waste (dried peel) used as an animal feed additive. The present method for monitoring TBZ residues in white and sweet potatoes and white potato waste (dried peel) is simple, rapid, and sensitive.
Analysis of 2,2,2-THfluoroethyl Derivatives of Carboxylic Acid Herbicides by Gas Chromatography with Mass-Selective and Electron Capture Detection
Authors: Lee Arthur S , Hong Moo-Ki , Smith Albert E
Published: February 2020

A method for derivatizing carboxylic acid herbicides with 2,2,2-trifluoroethanol (TFE) in preparation for gas chromatographic (GC) analysis was developed. Esterification efficiency was determined by GC with electron capture detection (ECD), and esters were identified by GC with mass-selective detection (MSD). On the basis of reaction temperature for optimum esterification efficiency, 13 common carboxylic acid herbicides were separated into 2 groups before reaction with TFE. TFE derivatization was optimized for simultaneous analyses by altering reaction temperature, reaction time, and concentration of sulfuric acid in reaction solutions. The method is simple, safe, and economical, and it gives good resolution without a laborious cleanup. Recovery of 13 analytes from water, taken from a pesticide residue well, was greater than 80% for all except 2 analytes. The well-water was fortified with analytes at the lower microgram-per-liter concentrations required for detection of pesticide residues in potable water systems. The method can simultaneously determine multiple herbicide residues in water samples with a high degree of accuracy and precision.
Rapid and Simple Method for Determination of Cholesterol in Processed Food
Authors: Naeemi Esmaeel D , Ahmad Nissar , Al-Sharrah Tahani K , Behbahani Montaha
Published: February 2020

An improved method for determination of cholesterol in processed food with only one extraction and without solvent removal was developed. Total time to analyze a sample including gas chromatographic (GC) analysis is 45 min. Food samples spiked with internal standard are hydrolyzed in a screw-capped vial with saturated methanolic KOH. Cyclohexane is added to the mixture, and the upper layer is analyzed by GC on a capillary column. Average recoveries of spiked white eggs are 99 ± 0.5%. Fifteen types of processed food containing shrimp, fish, meat, cheese, eggs, and vegetables were analyzed with this method and with the AOAC method.
Dairy Product Analysis: Identification of Microorganisms by Mid-Infrared Spectroscopy and Determination of Constituents by Raman Spectroscopy
Authors: Fehrmann Angela , Franz Monika , Hoffmann Andreas , Rudzik Lutz , Wüst Eberhard
Published: February 2020

Identification of microorganisms by traditional microbiological methods is time consuming. The German Federal Health Office has developed a method using mid-infrared spectroscopy to identify microorganisms rapidly. This method has been modified for application to microorganisms important in the dairy industry. Mid- and near-infrared spectroscopies are well-established methods for quantitative measurements of fat, protein, lactose, and solid content in a variety of products. A disadvantage of both methods is the huge absorption due to water; extraction of other components is complicated and can be achived only statistically. With Raman spectroscopy, water causes less absorption. We investigated the use of Raman spectroscopy as a quantitative method for milk powder.
Polymerase Chain Reaction–Restriction Fragment Length Polymorphism Analysis: A Simple Method for Species Identification in Food
Authors: Meyer Rolf , Höfelein Christiane , Lüthy Jürg , Candrian Urs
Published: February 2020

The polymerase chain reaction (PCR) technique was applied to meat species identification in marinated and heat-treated or fermented products and to the differentiation of closely related species. DNA was isolated from meat samples by using a DNA-binding resin and was subjected to PCR analysis. Primers used were complementary to conserved areas of the vertebrate mitochondrial cytochrome b (cytb) gene and yielded a 359 base-pair (bp) fragment, including a variable 307 bp region. Restriction endonuclease analysis based on sequence data of those fragments was used for diffferentiation among species. Restriction fragment length polymorphisms (RFLPs) were detected when pig, cattle, wild boar, buffalo, sheep, goat, horse, chicken, and turkey amplicons were cut with Alul, Rsal, Taql, and Hinfl. Analysis of sausages indicates the applicability of this approach to food products containing meat from 3 different species. The PCR–RFLP analytical method detected pork in heated meat mixtures with beef at levels below 1%, and the method was confirmed with porcine- and bovine-specific PCR assays by amplifying fragments of their growth hormone genes. Inter- and intraspecific differences of more than 22 animal species with nearly unknown cytb DNA sequences, including hoofed mammals (ungulates), and poultry were determined with PCR–RFLP typing by using 20 different endonucleases. This typing method allowed the discrimination of game meats, including stag, roe deer, chamois, moose, reindeer, kangaroo, springbok, and other antelopes in marinated and heat-treated products.
Microwave-Assisted Extraction as an Alternative to Soxhlet, Sonication, and Supercritical Fluid Extraction
Authors: Lopez-A Vila Viorica , Young Richard , Teplitsky Nataly
Published: February 2020

Microwave-assisted extraction (MAE), Soxhlet, soni cation, and supercritical fluid extraction (SFE) were compared in their ability to extract 95 compounds listed in U.S. Environmental Protection Agency Method 8250. Freshly spiked soil samples and 2 standard reference materials were extracted with hexane-acetone (1 + 1) by MAE and Soxhlet extraction, with methylene chloride-acetone (1 + 1) by sonication extraction, and with supercritical carbondioxide modified with 10% methanol by SFE. Results indicate that MAE is a promising extraction technique. Of 94 compounds for which we are reporting data, 51 compounds gave MAE recoveries of >80%; 33,50-79%; 8,20-49%; and 2, <19%. Soxhlet extraction gave very similar results: 50 recoveries were >80%; 32,50-79%; 8,20-49%; and 4, <19%. Sonica tion recoveries were slightly higher: 63 values were >80%; 25,50-79%; 4,20-49%; and 2, <19%. SFE recoveries were the lowest: 37 values were >80%; 37, 50-79%; 12,20-49%, and 8, <19%. MAE gave the best precision: relative standard deviations (RSDs) were <10% for 90 of 94 compounds. Soxhlet extraction gave the worst precision: only 52 of 94 samples gave RSDs ≤10%. Although MAE looks promising, 15 polar basic compounds extracted at 115°C with hexane acetone for 10 min (1000 W power) gave poor recoveries. Because no technique gave acceptable recoveries for these polar compounds, we investigated their extraction with MAE using acetonitrile at 50° and 115°C. Ten of the 15 compounds were quantitatively recovered (>70%) with acetonitrile at 115°C.
Estimated Content Percentages of Volatile Liquids and Fat Extractables in Ready-to-Eat Foods
Authors: Daft James L , Cline J Kevin , Palmer Rosetta E , Sisk Ronald L , Griffitt Kenneth R
Published: February 2020

Content percentages of volatile liquids and fat ex tractables in 340 samples of ready-to-eat foods were determined gravimetrically. Volatile liquids were determined by drying samples in a microwave oven with a self-contained balance; results were printed out automatically. Fat extractables were ex tracted from the samples with mixed ethers; ex tracts were dried and weighed manually. The sam ples, 191 nonfat and 149 fatty (containing ca 2% or more fat) foods, represent about 5000 different food items and include infant and toddler, ethnic, fast, and importeditems. Samples were initially pre pared for screening of essential and toxic elements and chemical contamination by chopping and mix ing into homogenous composites. Content determi nations were then made on separate portions from each composite. Content results were put into a da tabase for evaluation. Overall, mean results from both determinations agree with published data for moisture and fat contents of similar food items. Co efficients of variation, however, were lower for de termination of volatile liquids than for that of fat ex tractables.
Interpretation of Combined H SNIF/NMR and C SIRA/MS Analyses of Fruit Juices To Detect Added Sugar
Authors: Martin Gilles G , Hanote Valérie , Lees Michéle , Martin Yves-Loïc
Published: February 2020

The site-specific natural isotopic fractionation studied by nuclear magnetic resonance (SNIF/NMR) method measures site-specific isotope contents in a variety of organic compounds by deuterium nuclear magnetic resonance spectroscopy. This technique, together with SIRA/MS (stable isotope ratio analysis/mass spectrometry) provides a powerful tool for food authentication and characterization. By using the ethanol resulting from sugar fermentation as a molecular probe, SNIF/NMR (deuterium) and SIRA/MS (13C) have been used together for authentication of fruit juices. The influence of deu terium content of the fermentation water on the iso topic parameters is shown and a means for normal izing the results is proposed. A large number of authentic juices have been analyzed to define the variation of isotopic ratios in natural juices. On the basis of these data, a set of rules was designed to enable interpretation of isotopic parameters in terms of possible adulteration of fruit juices by sugar addition. Results of analyses of Florida orange juice are presented. Orange juice samples from Brazil and Israel are included as 2 extreme cases. Assignment limits for a sample of orange juice of unknown origin also are given. These assignment limits are also provided for apple and grapefruit juices.
Identification of Ambergris from the New Bedford Whaling Museum by Nuclear Magnetic Resonance Spectroscopy
Authors: Moniz George A , Hammond Gerald B
Published: February 2020

A new method for the separation and identification of ambrein in ambergris using adsorption chromatography and 1H and 13C Fourier transform nuclear magnetic resonance spectroscopy (FT-NMR) is presented. We demonstrated the effectiveness of this method by analyzing an approximately 85-year-old sample of suspected ambergris from the New Bedford Whaling Museum (New Bedford, MA). Results prove that ambrein remains a major constituent of ambergris even after 85 years of storage under ordinary conditions.
Liquid Chromatographic Determination of Nalidixic Acid in Pharmaceutical Preparations
Authors: Walker Samuel T
Published: February 2020

A simple, rapid, and environmentally safe liquid chromatographic (LC) method was developed for the qualitative and quantitative determination of pharmaceutical preparations of nalidixic acid. The new method was applied to commercial preparations of tablets and a suspension of nalidixic acid and found to be satisfactory for both quantitative and qualitative determinations. Previous LC methods either used chloroform to extract, which we were trying to eliminate, or used a mobile phase of about pH 2.5, which will destroy the column coating. TheLC system for the new method uses sul fanilic acid as internal standard, a μ-Bondapak C18 column, and a mobile phase of methanol, 0.0045M dibasic potassium phosphate, and 0.0072M hexadecyltrimethyiammmonium bromide. The detection wavelength is 254 nm. The sample is dissolved in methanol, and an aliquot is injected through a 20 μL injection loop. Average recoveries ranged from 99.4 to 101.3%.
Salmonella Detection in Dried Milk Products by Motility Enrichment on Modified Semisolid Rappaport-Vassiliadis Medium: Collaborative Study
Authors: Bolderduk Robert F , Milas John E ,   Collaborators:, Asperger H , Becker H , Chatron S , Cordier J L , DeSmedt J , Gonzalez D , Hammers A , Hoekstra J , Kanitz L , McDonagh S , Nowacki R , Oggel J , Quinlan J , Stolpenir L , Trottier Y L , Van Gestel G , Van Oudenallen A , West W , Zschaler R
Published: February 2020

A collaborative study involving 19 laboratories was performed to validate motility enrichment on modified semisolid Rappaport-Vassiliadis (MSRV) medium for rapid detection of motile Salmonella in dried milk products. The MSRV method was compared with the AOAC culture method for detection of Salmonella in nonfat milk powder, whole milk powder, whey powder, casein powder, and butter milk powder. Samples were artificially inoculated with Salmonella at 2 levels of contamination. Un-inoculated control samples were included for each type of product. The sensitivity rates were 100% for the MSRV method and 99.0% for the AOAC culture method, while the specificity rate was 100.0% for both methods. Only for the samples of whey powder, which were inoculated with H2S negative S. tennessee, was there a significant difference in the proportion of samples positive by MSRV and the culture procedure. The MSRV method for detection of motileSalmonella in dried milk products has been adopted first action by AOAC INTERNATIONAL.
Determination of Patulin in Apple Juice by Liquid Chromatography: Collaborative Study
Authors: Brause Allan R , Trucksess Mary W , Thomas Frederick S , Page Samuel W ,   Collaborators:, Burke J , Tanner A , Hammack S , Woodward B B , Post S , Simmons D , Cherix G , Kennedy M , Lewis S , English N , Coppola E D , Kline L , Coopersmith A , Foos J F , Eisele T A , Krueger D A ,   Collaborators:, Hofsommer H J , MacDonald S , Hesford F , Lea A , Symonds P , Martin G , Acar J , Eksi A , Ardenghi R , Weiss J , Lee B , Woidich H
Published: February 2020

An AOAC International-International Union of Pure and Applied Chemistry-International Fruit Juice Union (AOAC-IUPAC-IFJU) collaborative study was conducted to evaluate a liquid chromatographic (LC) procedure for determination of patulin in apple juice. Patulin is a mold metabolite found naturally in rotting apples. Patulin is extracted with ethyl acetate, treated with sodium carbonate solution, and determined by reversed-phase LC with UV detection at 254 or 276 nm. Water, water-tetrahydrofuran, or water-acetonitrile was used as mobile phase. Levels determined in spiked test samples were 20, 50,100, and 200 μg/L. A test sample naturally contaminated at 31 μg/L was also included. Twenty-two collaborators in 10 countries analyzed 12 test samples of apple juice. Recoveries averaged 96%, with a range of 91-108%. Repeatability relative standard deviations (RSDr) ranged from 10.9 to 53.8%. The reproducibility relative standard deviation (RSDR) ranged from 15.1 to 68.8%. The LC method for determination of patulin in apple juice has been adopted first action by AOAC INTERNATIONAL.
Assessment of Immunochemical Methods for the Analysis of Trichothecene Mycotoxins in Naturally Occurring Moldy Corn
Authors: Park Joung J , Chu Fun S
Published: February 2020

The efficacy of various immunochemical methods for simultaneous analysis of different trichothe-cene mycotoxins in corn samples naturally contaminated with various Fusarium molds was evaluated. Antibodies against either T-2 tetraol tetraacetate (T-2-4ol-4Ac) or deoxynivalenol triacetate (Tri-Ac-DON) were used in the enzyme- linked immunosorbent assay (ELISA) and radioimmunoassay (RIA) for total type A and total DON-related trichothecenes (TCTCs), respectively. Specific antibodies against T-2 toxin were used in an RIA for analysis of T-2 toxin alone. Analytical recoveries of T-2 toxin analyzed as T-2-4ol-4Ac by ELISA and T-2 toxin by RIA at 10-200 ppb were 83.5-123% and 81.8-110.6%, respectively. T-2 toxin accounts for about 30% of total type A TCTCs by both liquid chromatography (LC)-ELISA and RIA methods. The correlation coefficients (r) of total type A TCTC levels versus T-2 toxin level by RIA was 0.725 (p < 0.0001). A good correlation (r = 0.84 and p = 0.04) also was found for T-2 toxin levels obtained by LC-ELISA and RIA methods. In addition to T-2 toxin, HT-2 toxin, diacetoxyscirpenol, and T-2 tetrol were found in samples containing high levels of type A TCTCs by LC-ELISA. For analysis of DON alone, samples were treated with a Sep-Pak C18 cartridge to remove other acetylated DONs before RIA. Recovery of DON after the C18 cartridge treatment was 90%. Overall analytical recoveries of DON as Tri-Ac-DON (sample with no C18 treatment) and DON alone (with C18 treatment) at 10-500 ppb were 81.3-94% and 72.7-104%, respectively. RIA revealed that DON accounts for about 50% of total DON-related TCTCs. The coefficient of correlation between total DON-related TCTCs and DON levels was 0.84 (p < 0.0001).
Liquid Chromatographic Method for Determination of Total Avermectin Bi and 8,9-Z-Avermectin B1 Residues in Hops
Authors: Cobin Janice A , Johnson Nelson A
Published: February 2020

A liquid chromatographic method has been developed and validated for determination of avermectin B1 and 8,9-Z-avermectin B1 residues in dried hops. The dried hops are rehydrated and subsequently extracted with a methanol-water mixture.The aver- mectins are partitioned into hexane and the hexane extract is concentrated (purified) on an amino- propyl solid-phase extraction column. The purified extract is derivatized with trifluoroacetic anhydride, and the derivatized avermectins are analyzed by re versed-phase liquid chromatography with fluorescence detection. Recoveries of the avermectins fromdried hops fortified with approximately 51000 ng/g avermectin B1a or 8,9-Z-avermectin B1a ranged from 73 to 108% with an overall average recovery of 95%. The limit of quantitation is 5 ng/g (signal-to-noise ratio [S/N] > 10), and the limit of detection is 2 ng/g (S/N > 3) for each analyte. The assay procedure provides a simple, rapid, and sensitive method for monitoring the total avermectin residues in hops.
Determination of Diesel Fuel and Motor Oil in Water and Wastes by a Modified Diesel-Range Organics Total Petroleum Hydrocarbon Method
Authors: Draper William M , Dhaliwal Joginder S , Perera S Kusum , Baumann Frank J
Published: February 2020

The American Petroleum Institute method for determination of diesel-range total petroleum hydrocarbon (TPH) by gas-liquid chromatography with flame ionization detection was modified to allow simultaneous determination of motor oil. Motor oil elutes as a broad hump of unresolved alkanes and can be distinguished readily from diesel fuel and other fuel oils by its profile. The boiling point ranges for No. 2 diesel fuel and motor oil are C10– C21 and C21–C38, respectively, and these ranges define TPHs in diesel fuel (TPH-D) and motor oil (TPH- M). By this convention, less than 6% of No. 2 diesel is characterized as TPH-M, and less than 9% of motor oil is quantitated as TPH-D. Inlet discrimination was observed when motor oil was injected with a splitless injector. Accurate motor oil quantitation with splitless sample introduction requires calibration with the product or triacontane, which has a similar response factor. Detector response to motor oil (and other petroleum products) and a homologous series of n-alkanes was nearly constant when on-column injection was used. Instrument detection limit for motor oil was about 0.5 μg (split- less injection, total area under the curve), and the widest linear range (up to 100 μg) was obtained by subtracting the solvent chromatogram. Procedures for isolation of motor oil from oil-in-water (O/W) and water-in-oil (W/0) emulsions are described. Method detection limits for diesel fuel and motor oil in purified water were 0.041 and 1.5 mg/L, respectively.
Improved Gas Chromatographic Analysisof Organophosphorus Pesticides with Pulsed Splitless Injectiony
Authors: Wylie Philip , Uchiyama Katsura
Published: February 2020

Gas chromatographic (GC) analysis of 6 organo-phosphorus pesticides (methamidophos, acephate, omethoate, diazinon, dimethoate, and chlorpyrifos) was performed with cool on-column, splitless, and pulsed splitless injections and with nitrogen–phos phorus or mass-selective detection. The pulsed splitless technique uses a high column flow rate during injection to sweep the sample out of the inlet rapidly, reducing analyte loss due to adsorption or thermal decomposition. After injection, the column flow rate is automatically reduced to normal values for chromatographic analysis. Pesticide recoveries for splitless and pulsed splitless injections were determined by comparison of GC peak areas with those obtained with cool on-column injection. With conventional splitless injection at a column flow rate of 5 mL/min, recoveries of acephate, omethoate, and methamidophos were only 57, 63, and 71 %, respectively. Pulsed splitless methods with very fast injection flow rates dramatically improved recoveries, with all 6 pesticides falling in the 97–102% range. Because column flow rates are much less for GC with mass spectral detection (GC/MS), recoveries with splitless injection were lower and improvements with pulsed splitless injection were less dramatic for GC/MS. When splitless injection was used, recoveries of the 6 pesticides spiked into a green bean matrix were better than those of pesticides dissolved in pure solvent, presumably because matrix compounds compete with pesticides for active sites in the inlet. By using pulsed splitless injection of solvent standards with very fast initial column flow rates, systematic analyte losses in the inlet were eliminated, making recoveries of pesticides from solvent and green bean matrix very similar.
Determination of Allantoin in Biological, Cosmetic, and Pharmaceutical Samples
Authors: Bin Chen Xue , Matuszewski Wojciech , Kowalczyk Jan
Published: February 2020

Methods for determining allantoin in biological, cosmetic, and pharmaceutical samples are reviewed. The methods cover 3 main categories: spectrophotometry, alkalimetric titration, and chromatography (thin-layer and liquid). Comments are given on suitability for different sample types and on further development of methods for allantoin determination.