bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Paraffins in Food Simulants and Packaging Materials by Liquid Chromatography with Evaporative Mass Detection and Identification of Paraffin Type by Liquid Chromatography/Gas Chromatography and Fourier Transform Infrared Spectroscopy
Authors: Simal-Gándara Jesús , Sarria-Vidal Miguel , Rijk Rinus
Published: February 2020

A liquid chromatographic method with evaporative mass detection (EMD) is described for the determination of paraffins in food contact materials that do not contain polyolefin oligomers, or paraffins migrating from these materials into fatty food simulants or certain simple foods. A normal-phase column operating at maximum column efficiency separates nonparaffinic and paraffinic materials without resolving the latter into individual components, and EMD is used to quantitate the paraffins. An on-line qualitative method that uses liquid chromatography/gas chromatography with flame ionization detection discriminates between paraffin waxes and oils in food contact materials, food simulants, and certain simple foods; a Fourier transform infrared spectrophotometric qualitative method also discriminates between waxes and oils, but is usually restricted to food contact materials that do not contain polyolefins and to migration experiments with organic solvents as fatty food simulants (with some other fatty food simulants, paraffin type must then be identified in the food contact material).
Measurement of Bromate in Bread by Liquid Chromatography with Post-Column Flow Reactor Detection
Authors: Himata Katsuichi , Noda Masaaki , Ando Susumu , Yamada Yuji
Published: February 2020

This method is suitable for the determination of bromate residues in a variety of baked goods. The peer-verified method trial was performed on white bread, multigrain bread, and coffee cake spiked with known levels of potassium bromate. The analytical portion is extracted with deionized water to remove bromate from the bulk of the baked product. The aqueous extract is carried through a series of steps to remove co-extractives that would interfere with the liquid chromatography (LC) in the determinative step or hasten the deterioration of the LC column. The extract is filtered before passing it through a reversed-phase solid-phase extraction (SPE) column and a cation-exchange column in the silver form to remove lipids and chloride, respectively. Ultrafiltration is then used to remove proteins with molecular weights of >30 000 daltons. Finally, a cation-exchange column in the sodium form is used to remove silver ions from the extract. The determinative step uses LC with a reversed-phase column and an ion-pairing agent in the mobile phase. Detection is based on the post-column reaction of bromate with o-dianisidine to form an oxidation product that is quantitated spectrophotometrically at 450 nm. Overall agreement between the submitting and peer laboratories was quite good. For bromate levels of 10–52 ppb, overall mean recoveries were 76.9 and 78.8% for the submitting and peer laboratories, respectively. The standard deviations were higher for the results of the peer laboratory, probably because of the generally higher level of baseline noise present in the chromatograms. The results demonstrate that the method provides adequate accuracy with low-fat as well as high-fat foods. Bromate at levels as low as 5 ppb (ng/g) can be detected with the method.
Application of Partial Least-Squares Calibration to Phosphorimetric Data for Determination of Polycyclic Aromatic Hydrocarbons in Spiked Environmental Samples
Authors: Carretero A Segura , Galera M Martinez , Blanco C Cruces , García M D Gil , Gutiérrez A Fernández , Vidal J L Martínez
Published: February 2020

A partial least-squares calibration method is proposed, for the first time, for phosphorescence signals. The proposed method is based on the determination of phenanthrene, fluoranthene, and benz[a]anthracene by room temperature phosphorimetry, using microemulsion solutions. The emission and first-derivative emission spectra of the ternary mixtures were tested to perform the calibration matrix. Improved recoveries were found for the prior differentiation step in the analysis of ternary mixtures of these polycyclic aromatic hydrocarbons in road dust samples. The proposed method yielded recoveries ranging from 93.2 to 115.3%, with relative standard deviations of < 6.8%.
Value Assignment of Nutrient Concentrations in Five Standard Reference Materials and Six Reference Materials
Authors: Sharpless Katherine E , Gill Lisa M
Published: February 2020

A number of food-matrix reference materials (RMs) are available from the National Institute of Standards and Technology (NIST) and from Agriculture Canada through NIST. Most of these materials were originally value-assigned for their elemental composition (major, minor, and trace elements), but no additional nutritional information was provided. Two of the materials were certified for selected organic constituents. Ten of these materials (Standard Reference Material® [SRM] 1563 Cholesterol and Fat-Soluble Vitamins in Coconut Oil [Natural and Fortified], SRM 1566b Oyster Tissue, SRM 1570a Spinach Leaves, SRM 1974a Organics in Mussel Tissue (Mytilus edulis), RM 8415 Whole Egg Powder, RM 8418 Wheat Gluten, RM 8432 Corn Starch, RM 8433 Corn Bran, RM 8435 Whole Milk Powder, and RM 8436 Durum Wheat Flour) were recently distributed by NIST to 4 laboratories with expertise in food analysis for the measurement of proximates (solids, fat, protein, etc.), calories, and total dietary fiber, as appropriate. SRM 1846 Infant Formula was distributed as a quality control sample for the proximates and for analysis for individual fatty acids. Two of the materials (Whole Egg Powder and Whole Milk Powder) were distributed in an earlier interlaboratory comparison exercise in which they were analyzed for several vitamins. Value assignment of analyte concentrations in these 11 SRMs and RMs, based on analyses by the collaborating laboratories, is described in this paper. These materials are intended primarily for validation of analytical methods for the measurement of nutrients in foods of similar composition (based on AOAC INTERNATIONAL's fat–protein–carbohydrate triangle). They may also be used as “primary control materials” in the value assignment of in-house control materials of similar composition. The addition of proximate information for 10 existing reference materials means that RMs are now available from NIST with assigned values for proximates in 6 of the 9 sectors of the AOAC triangle. Five of these materials have values assigned for total dietary fiber—the first such information provided for materials available from NIST.
Effect of Temperature and Solvent Composition on Extraction of Fumonisins B1 and B2 from Corn Products
Authors: Lawrence James F , Niedzwiadek Barbara , Scott Peter M
Published: February 2020

Fumonisins B1 and B2 were extracted from naturally contaminated corn products by using different extraction solvent compositions (methanol–water, acetonitrile–methanol–water, ethanol–water, and 100% water) and a range of temperatures from ambient to 150°C. Ground samples of several corn products and 1 rice sample were mixed with an adsorbent material (Hydromatrix™), and the fumonisins were extracted in 2 sequential 5 min static extractions at various temperatures. The combined extracts were cleaned up and analyzed by reversed-phase liquid chromatography with fluorescence detection after o-phthaldialdehyde–mercaptoethanol derivatization. The results showed a clear influence of temperature and solvent composition on recovery of fumonisins from some matrixes. With acetonitrile–methanol–water (1 + 1 + 2) the quantity of fumonisins extracted from naturally contaminated taco shells almost tripled in going from 23° to 80°C, and increased by another 30% when ethanol–water (3 + 7) was used as extraction solvent at 80°C. Similar results were obtained with nacho chips. These effects were less pronounced with cornmeal, and small differences due to temperature and solvent composition were observed for corn flakes and rice. The ethanol–water extraction solvent combinations were specifically evaluated in an effort to use the cheapest, least toxic, and most environmentally friendly solvents for organic residue analysis. At 80°C, ethanol–water combinations performed equally or better than methanol–water (8 + 2) or acetonitrile–methanol–water (1 + 1 + 2), combinations which are commonly used for fumonisin extractions. Even 100% water was successful for extracting fumonisins from the products, except for rice. However, increased amounts of water created technical problems and required an increased amount of Hydromatrix in the samples prior to extraction.
Characterization of Varietal Differences in Essential Oil Components of Hops (Humulus lupulus) by SFC–FTIR Spectroscopy
Authors: Auerbach Rita H , Dost Kenan , Davidson George
Published: February 2020

A supercritical fluid chromatographic method combined with Fourier-transform infrared spectroscopy detection (SFC–FTIR) was developed for determination of varietal differences in essential oil constituents in hops (Humulus lupulus). Infrared spectra (IR) of the major constituents of essential oil of hops were taken as films deposited on AgCl discs and compared with those obtained after chromatographic separation in the IR flow-cell with supercritical carbon dioxide (scCO2). Spectra from AgCl discs were comparable to those in scCO2, but in scCO2 most of the bands appeared approximately 8–10 cm−1 to higher wave numbers. Open-tubular SFC–FTIR analysis of the essential oil of 4 different hop varieties was performed. The SFC–FTIR chromatograms showed differences in the location and relative intensity of the peaks depending on the variety, which was further confirmed by consideration of their FTIR spectra.
Multiresidue Method for the Determination of Residues of 251 Pesticides in Fruits and Vegetables by Gas Chromatography/Mass Spectrometry and Liquid Chromatography with Fluorescence Detection
Authors: Fillion Julie , Sauvé François , Selwyn Jennifer
Published: February 2020

A method is described for the determination of 251 pesticide and degradation product residues in fruit and vegetable samples. Extraction of the sample with acetonitrile is followed by a saltingout step. Co-extractives are removed by passing a portion of the acetonitrile extract through an octadecyl (C18) solid-phase extraction cleanup cartridge and then, in a second cleanup, through a carbon cartridge coupled to an amino propyl cartridge. Determination is by gas chromatography with mass-selective detection in the selected-ion monitoring mode, and by liquid chromatography with post-column reaction and fluorescence detection for N-methyl carbamates. The method has been used for analysis of various fruits and vegetables, such as apple, banana, cabbage, carrot, cucumber, lettuce, orange, pear, pepper, and pineapple. Limits of detection range between 0.02 and 1.0 mg/kg for most compounds. Over 80% of the compounds have a limit of detection of ≤0.04 mg/kg.
Use of a Particle Beam Interface Combined with Mass Spectrometry/Negative Chemical Ionization to Determine Polar Herbicide Residues in Soil by Liquid Chromatography
Authors: Jiménez Juan J , Bernal José L , Del Nozal María J , Martín María T
Published: February 2020

The use of mass spectrometry/negative chemical ionization (MS/NCI), in combination with selected-ion monitoring, allows sensitive and selective determination of polar and thermally unstable herbicide residues by liquid chromatography coupled to a particle beam interface. The method has been applied to the analysis of soil samples for herbicide residues, using various procedures for their extraction and employing matrix-standard calibration to avoid quantitative errors due to transfer of matter through the interface. Data for the fragment ions found in the MS/NCI procedure and chromatograms from analyses of real samples are also presented.
Rapid Target Analysis for Pesticides in Water by Online Coated Capillary Microextraction Combined with Liquid Chromatography and Tandem Mass Spectrometry
Authors: Hartmann Holger , Burhenne Jürgen , Müller Karin , Frede Hans G , Spiteller Michael
Published: February 2020

The applicability of online trace enrichment with custom-made coated capillaries combined with tandem mass spectrometry was demonstrated for the target analysis of selected pesticides (mainly herbicides, e.g., triazines, phenylureas, and acetanilides) in water. The developed method allows rapid determination of several widely used plant protectants within a total analysis time of 11 min. Good linearity (r ≥ 0.995) was obtained for the selected pesticides in the range of 0.050–50 μg/L. The relative standard deviations (RSDs) of the peak areas were ≤3.8% for spiked Milli-Q water (5 μg/L). The RSDs obtained in analyses of spiked (1 μg/L) water samples (brook water, river water, sewage plant effluent) ranged from 2.9 to 6.8%, indicating low influence of the matrix on enrichment and detection. The detection limits, which ranged from 10 to 90 ng/L, fulfilled the requirements of the European regulations for drinking water. The polyacrylate coating of the extraction capillary showed good stability in the presence of water and acetonitrile and allowed ≥100 extractions with 1 capillary.
Detection of Anabolic Residues in Misplaced Implantation Sites in Cattle
Authors: Daxenberger Andreas , Lange Iris G , Meyer Karsten , Meyer Heinrich H D
Published: February 2020

Eight weeks before slaughter, 26 heifers, 2 calves, and 1 steer were implanted with licensed anabolic preparations at off-label injection sites. After slaughter, 24 of 31 implantation sites (77%) were detected. Residual pellets of Revalor H contained a mean of 42.9 mg trenbolone acetate (range 19.8–57.7 mg) and 4.6 mg (1.96–6.45 mg) estradiol, corresponding to 30%(19.8–57.7%) and 32.7% (14.0–46.6%) of the originally applied dose, respectively. In the tissue areas containing residual Revalor H pellets, total residues ranged from 14.8 μg to 12.6 mg trenbolone acetate, 41.7 μg to 1.45 mg trenbolone, and 11.1 μg to 3.39 mg estradiol. The outer tissue areas of the injection sites contained <2 μg hormones. The preparations Synovex H, Finaplix H, Implus S, and Component EC behaved similarly to Revalor H. Residues of Synovex Plus were low, whereas the Compudose silicone rubber contained 58.8%of the implanted dose, but left no significant tissue residues. If implantation sites are processed in meat manufacturing, international threshold levels of the respective substances will be exceeded in tons of meat products.
Determination of Sulfonamides in Swine Meat by Immunoaffinity Chromatography
Authors: Li Jun Suo , Li Xi Wang , Yuan Jian Xiang , Wang Xin
Published: February 2020

A procedure was developed for the preparation of anti-sulfonamide (SA) group-specific antibodies and immunosorbents. Sulfonamide haptens and conjugates were synthesized by building spacer arms on an N1 group of 4-aminobenzensulfonamide. The anti-SA group-specific antibodies and immunosorbents were prepared successfully. After extraction with methanol–water (8 + 2), sulfamonomethoxine, sulfadimethoxine, and sulfaquinoxaline were cleaned up on immunoaffinity columns and determined by reversed-phase liquid chromatography with UV detection at 270 nm. The recoveries from fortified swine meat (10–100 μg/kg) ranged from 70.8 to 94.1%, with coefficients of variation of 3.4–12.9%. Limits of detection were 1–2 μg/kg.
Changes in Content and Composition of Dietary Fiber in Yellow Onions and Red Delicious Apples During Commercial Storage
Authors: Marlett Judith A
Published: February 2020

Changes in pectin composition and solubility are part of the softening process in apples during ripening and postharvest storage. Lignification may also occur with long-term storage. In the United States, apples and onions are harvested once yearly and then stored and marketed for the next 12 months. The changes that occur in the dietary fiber content and composition in Red Delicious apples and yellow Spanish onions during storage were studied, and the loss of fiber in peeled apples was determined. Dietary fiber was extracted by the enzymatic–chemical method of Theander and Westerlund. Storage had no effect on total or insoluble fiber content of apples; Klason lignin concentration was greater in samples stored for 12 months than in those stored for 0, 4, or 8 months. Peeling reduced apple fiber concentration about 25% by decreasing neutral and acidic sugars and Klason lignin in the insoluble fraction. The total fiber content of onions increased with storage, primarily by increasing the insoluble fiber content of uronic acids. The results suggest that the standardized, environmentally controlled storage of apples, as used in Washington State, has little effect on dietary fiber content. In contrast, the less rigorously controlled storage conditions for yellow Spanish onions increases the insoluble fiber fraction and uronic acid content.
Environmental Screening of Acidic Compounds Based on Capillary Zone Electrophoresis/Laser-Induced Fluorescence Detection with Identification by Gas Chromatography/Mass Spectrometry and Gas Chromatography/High-Resolution Mass Spectrometry
Authors: Brumley William C , Grange Andrew H , Kelliher Virginia , Patterson Dennis B , Montcalm Alice , Glassman Jack , Farley John W
Published: February 2020

This paper describes the application of capillary zone electrophoresis/laser-induced fluorescence detection (CZE/LIF) to the discovery of acidic compounds in environmental matrixes or the screening of extracts for acidic components. Published studies indicate that coal-derived materials contain a significant fraction of acidic compounds relative to materials derived from petroleum and shales. Such compounds may be useful as marker compounds for site assessment and source apportionment issues, and their identification may be important in toxicological and other health issues. We used deep-UV light from the frequency-doubled Ar ion laser at 244 and 257 nm to study extracts of samples. The CZE/LIF technique possesses good sensitivity and therefore overcomes one of the limitations of CZE with UV detection. The present work depends on high pressure/temperature solvent extraction of polynuclear aromatic hydrocarbon (PNA)-contaminated soil, followed by separation using CZE. The anionic analytes were separated by using borate or phosphate buffer (pH 9.2–12.3) after a chemical class separation. Samples were also characterized by gas chromatography/mass spectrometry (GC/MS) using full scans at low resolution, and elemental compositions were determined unequivocally by GC/high-resolution MS (GC/HRMS) using mass peak profiling (MPP). The similarity of low-resolution electron ionization mass spectra for a standard, 1-hydroxypyrene, and for a series of compounds in a contaminated-soil extract suggested that several types of phenolic and hydroxy-PNAs were present, including hydroxylated derivatives of fluorenes, fluoranthenes, and pyrenes. GC/HRMS using MPP confirmed the elemental compositions of the hydroxyfluorenes and hydroxypyrenes (and presumably hydroxyfluoranthenes) as [C13H10O] and [C16H10O], respectively. A new version of the MPP software was written for the Finnigan-MAT 900S-Trap and was similar to that developed previously for the VG 250SE. Inclusion of a calibration ion in addition to a lock mass ion in the multiple-ion detection descriptor provided errors of <1 ppm for the 3 partial profiles of the analytes. A mass resolution of 31 000 was used to resolve the analyte signals from interferences evident in the full M+1 and M+2 profiles in the case of the hydroxyfluorenes. Derivatization was also performed to form the tert-butyldimethylsilyl derivatives of phenolic hydroxy groups as a further confirmation of structure.
Sensitivity and Specificity of the Test Kit BAX® for Screening/ E. coli O157:H7 in Ground Beef: Independent Laboratory Study
Authors: Hochberg Alan M , Gerhardt Paul N M , Cao Thoa K , Ocasio Wilfredo , Barbour W Mark , Mrozinski Peter M
Published: February 2020

An independent laboratory study of the BAX® for Screening/E. coli O157:H7 kit was conducted at the National Food Laboratory, Inc., Dublin, CA, to complete AOAC® Performance Tested MethodSM certification. The BAX system kit was compared with the BAM culture method and a modified BAM culture method for detection of E. coli O157:H7 in ground beef. The BAX system kit detected the target organism at levels approximately 10-fold lower than those that gave positive BAM results. This study validated product claims, and Performance Tested Method status was granted.
Liquid Chromatographic Preparative Method for Isolating Ergot Alkaloids, Using a Particle-Loaded Membrane Extracting Disk
Authors: Ware George M , Price Gina , Carter Lawrence , Eitenmiller Ronald R
Published: February 2020

A liquid chromatographic method is described for the determination of ergot alkaloids in wheat. Ergonovine, ergotamine, ergocornine, α-ergocryptine, and ergocristine are extracted from wheat with methanol–0.25% concentrated H3PO4 (40 + 60) pH 2.2, cleaned up by using a solid-phase extraction (SPE) disk, and separated by reversed-phase liquid chromatography with fluorescence detection. Ergot alkaloids are basic compounds that form water-soluble salts in acidic aqueous solution. Because ergot alkaloid salts are positively charged, they can be easily and selectively trapped on a negatively charged strong cation-exchange SPE disk. A strong wash solvent, methanol–0.25% concentrated H3PO4 (40 + 60) was used to remove matrix interferences not bonded by ionic interactions with the cation-exchange column. The ergot alkaloids were eluted from the ion-exchange column by adjusting the pH of the elution solvents to slightly basic conditions (pH 9). The SPE disk concentrated and cleanly separated the ergot alkaloids from matrix interferences. Standard calibration curves for ergot alkaloids for the concentration range 0.1–2.0 μg/mL were linear. The SPE disk had a column capacity equivalent to about 1 g extracted wheat. At spiking levels of 2.3–46 ng/g for ergonovine and 20–400 ng/g for ergotamine, ergocornine, α-ergocryptine, and ergocristine, the mean recovery was 88.1% with a coefficient of variation (CV) of 5.33%. The recovery data ranged from 79.1 to 95.9%. Ergonovine had the lowest overall recovery and the largest CV. The method has an estimated reliable limit of detection and limit of quantitation of <5 and <20 ng/g, respectively, for each ergot alkaloid tested.
Fluorescence Spectra Measurement of Olive Oil and Other Vegetable Oils
Authors: Kyriakidis Nikolaos B , Skarkalis Paulos
Published: February 2020

Fluorescence spectra of some common vegetable oils, including olive oil, olive residue oil, refined olive oil, corn oil, soybean oil, sunflower oil, and cotton oil, were examined in their natural state, with a wavelength of 360 nm used as excitation radiation. All oils studied, except extra virgin olive oil, exhibited a strong fluorescence band at 430–450 nm. Extra virgin olive oil gave a different by interesting fluorescence spectrum, composed of 3 bands: one low intensity doublet at 440 and 455 nm, one strong at 525 nm, and one of medium intensity at 681 nm. The band at 681 nm was identified as the chlorophyll band. The band at 525 nm was at least partly derived from vitamin E. The low intensity doublet at 440 and 455 nm correlated with the absorption intensity at 232 and 270 nm of olive oil. The measurements of these fluorescence spectra were quick (about 5 min) and easy and could possibly be used for authentification of virgin olive oil.
Spectrophotometric Determination of Saponin in Yucca Extract Used as Food Additive
Authors: Uematsu Yoko , Hirata Keiko , Saito Kazuo , Kudo Ichiro
Published: February 2020

A spectrophotometric method was developed for the determination of saponin in Yucca extract or its preparation for food additive use. A saponin fraction of Yucca extract was prepared by column chromatography with porous polymer, and hydrolyzed with a 2 mol/L mixture of hydrochloric acid–ethanol (1 + 1) to generate sapogenin. Sapogenin amounts were determined by measuring absorbance at 430 nm, based on the color reactions with anisaldehyde, sulfuric acid, and ethyl acetate. Recoveries from Yucca extracts were 91.5–95.1%, and the detection limit was 10 mg/kg. Commercial Yucca extracts for food additive use were composed of 5.6–6.4% (w/w) saponin, making it a minor component.
Determination of 1,3-Benzodioxanes in Piper mullesua by High-Performance Thin-Layer Chromatography
Authors: Srivastava Shaifali , Gupta Madan M , Verma Ram K , Kumar Sushil
Published: February 2020

A new, simple, precise, and rapid high-performance thin-layer chromatographic method was developed for the determination of 6 benzodioxanes in Piper mullesua extract: 1′,3′-benzodioxole-5′-(2,4,8-triene-isobutyl nonanoate), 1′,3′-benzodioxole-5′-(2,4,12-triene-isobutyl tridecanoate), fargesin, sesamin, asarinin, 1′,3′-benzodioxole-5′-(2,4,8-triene-methyl nonanoate). The ingredients were separated on a precoated Silica Gel 60 F254 plate with a solvent system of toluene–acetone (92 + 8). The 6 benzodioxanes were well separated and easily identified in this chromatographic system. The separated benzodioxanes were visualized by color development with a spray reagent consisting of 1 g vanillin dissolved in 100 mL H2SO4–ethanol (5 + 95, v/v). Quantitation was performed by scanning the spots and comparing the integrated areas of compounds in samples with those of standards. Recoveries from samples spiked with known amounts of the benzodioxanes were excellent. The results were comparable with those estimated by liquid chromatography.
Assay of Naproxen in Rat Serum by High-Performance Thin-Layer Chromatography/Densitometry
Authors: Guermouche Moulay-Hassane , Atik Nadia , Chader Hocine
Published: February 2020

A simple, sensitive, and reproducible high-performance thin-layer chromatographic method using densitometry is presented for the determination of naproxen in rat serum. Only 0.1 mL serum was used for extraction. Separations were performed on 10 × 10 cm plates coated with silica gel, with toluene–ethyl acetate–acetic acid (82 + 15 + 3) as the mobile phase. Benzophenone was used as the internal standard. Quantification was performed by densitometry at 260 nm. The response for naproxen was linear ( r = 0.992) over the range 2–100 mg/L. Method validation demonstrated good recoveries (92–96%), sensitivity (limit of quantitation, 1 mg/L), repeatability of sample application (4%), repeatability of the method (8%), and intermediate precision (5%). The procedure was applied to the quantitation of naproxen in rat serum.
Validation of a High-Performance Thin-Layer Chromatographic Method for Trace Analysis for Some Generic Drugs Affecting Gastrointestinal Function
Authors: Novaković Jasmina
Published: February 2020

To prevent cross-contamination between pharmaceutical products manufactured with the same equipment, cleanup procedures must be introduced before the manufacture of a new product begins. From an analytical point of view, it is crucial to select and validate a suitable analytical method to determine contaminants in the rinse water, swabs, and the placebo of the next product. High performance thin-layer chromatography (HPTLC) was chosen in our laboratory for this purpose and was optimized to meet the requirements of trace determination. The method was validated in terms of the limit of detection, limit of quantitation (LOQ), linearity close to the LOQ, sample preparation from the swab media and from the placebo of the next product made with the same equipment (recovery), precision, selectivity (interference from the swab and placebo matrixes), resolution (from related compounds), and robustness. The HPTLC method was applied to 2 different generic drugs affecting gastrointestinal function—the water-soluble H2-receptor antagonist ranitidine hydrochloride (RHCl) and the water-insoluble choleretic drug ursodeoxycholic acid (UDCA). Chromatography was performed on silica plates by using toluene–methanol–diethylamine (9 + 1 + 1, v/v/v) and n-heptane–ethyl acetate–glacial acetic acid (5 + 5 + 1, v/v/v) as the mobile phases for RHCl and UDCA, respectively. RHCl was measured in situ at 320 nm, whereas the detection of UDCA was performed at 502 nm after postchromatographic derivatization. The method was used for the determination of RHCl and UDCA in the swabs, the final rinse water, and the placebo batch after the cleanup process.
Immunochemical Applications in Environmental Science
Authors: Emon Jeanette M Van
Published: February 2020

Immunochemical methods are based on selective antibodies combining with a particular target analyte or analyte group. The specific binding between antibody and analyte can be used to detect environmental contaminants in a variety of sample matrixes. Immunoassay methods provide cost-effective, sensitive, and selective analyses for many compounds of environmental and human health concern. Immunoaffinity chromatography methods have been integrated with chromatographic methods and are also being used as efficient sample preparations prior to immunochemical or instrumental detection. Immunosensors show promise in obtaining rapid online analyses. These and other advancements in immunochemical methods continue the expansion of their role from field screening methods to highly quantitative procedures that can be easily integrated into the environmental analytical laboratory.
Sensitive Determination of n-Hexane and Cyclohexane in Human Body Fluids by Capillary Gas Chromatography with Cryogenic Oven Trapping
Authors: Kondo Kei , Lee Xiao-Pen , Kumazawa Takeshi , Sato Keizo , Watanabe-Suzuki Kanako , Seno Hiroshi , Suzuki Osamu
Published: February 2020

A sensitive method was developed for determination of n-hexane and cyclohexane in human body fluids by headspace capillary gas chromatography (GC) with cryogenic oven trapping. Whole blood and urine samples containing n-hexane and cyclohexane were heated in a 7.5 mL vial at 70°C for 15 min, and 5 mL of the headspace vapor was drawn into a glass syringe. All vapor was introduced through an injection port of a GC instrument in the splitless mode into an Rtx-Volatiles middle-bore capillary column at an oven temperature of −40°C for trapping volatile compounds. The oven temperature was programmed to 180°C for GC with flame ionization detection. These conditions gave sharp peaks for both n-hexane and cyclohexane, a good separation of each peak, and low background impurities for whole blood and urine. The extraction efficiencies of n-hexane and cyclohexane were 13.2–30.3% for whole blood and 12.7–20.7% for urine. The coefficients of within-day variation in terms of extraction efficiency of both compounds were 5.0–9.5% for whole blood and 3.8–10.8% for urine; those of day-to-day variationfor the compounds were not greater than 16.6%. The regression equations for n-hexane and cyclohexane showed good linearity in the range of 5–500 ng/0.5 mL for whole blood and urine. The detection limits (signal-to-noise ratio = 3) for both compounds were 1.2 and 0.5 ng/0.5 mL for whole blood and urine, respectively. The data on n-hexane or cyclohexane in rat blood after inhalation of each compound are also presented.
Charm Safe-Level β-Lactam Test for Amoxicillin, Ampicillin, Ceftiofur, Cephapirin, and Penicillin G in Raw Commingled Milk
Authors: Salter Robert S , Legg David , Ossanna Nancy , Boyer Cheryl , Scheemaker Joan , Markovsky Robert , Saul Steven J
Published: February 2020

The Charm Safe-Level β-Lactam Test was evaluated by a U.S. Food and Drug Administration (FDA) test protocol administered by the AOAC–Research Institute. The sensitivity and selectivity of the test were evaluated with >800 negative raw commingled and drug-fortified milk samples by the manufacturer and an independent laboratory. Probit analysis by the independent laboratory determined the following 90% positive levels with 95% confidence: amoxicillin, 5.6 ppb; ampicillin, 8.5 ppb; cephapirin, 13.7 ppb; ceftiofur, 46.2 ppb; and penicillin G, 3.6 ppb. These values were within a range of ±20% of the manufacturer's data. Selection of negative samples met confidence specifications. Ruggedness parameters were studied and defined, and the stability of frozen milk was verified. There were no interferences from somatic cells (1 000 000 somatic cell count/mL) or bacteria (300 000 colony-forming units/mL), or from 27 other non-β-lactam animal drugs. Test performance with raw milk samples containing incurred penicillin, ampicillin, and amoxicillin was consistent with the dose responses determined with fortified milk samples. Incurred cephalosporin in raw milk samples was detected at lower levels than was cephalosporin in fortified milk samples, presumably because of the presence of metabolite, as verified by other test methods. Quality control data support consistency in manufacture between batches and the stability of refrigerated test reagents for up to 1 year. Successful fulfillment of these criteria led to FDA certification of the test when used with a reader in U.S. milk testing programs.
TECRA® Unique™ Test for Rapid Detection of Salmonella in Food: Collaborative Study
Authors: Hughes Denise , Dailianis Angela E , Hill Louise , McIntyre Deborah A , Anderson Aimee ,   Collaborators:, Anderson A , Barrat C , Battista K , Beatty S , Blanch T , Briones D , Brooks R , Brown J , Burnie A , Clark T , Dailianis A , Destro C , Dijs B , Dombroski P , Fyfe R , Gebler J , Gerry A , Graham T , Hadjimichael D , Heaton S , Hetrick S , High E , Hill L , Hirt B , Hulett B , Hussain Z , Kalinowski R , Kerr D , Matouchi N , Maycock L , Munyard S , Murphy M , Remes A , Ristov K , Robbins R , Rodriquez R , Shebuski J , Simes V , Smith K , Vanderpoel S , Wang D
Published: February 2020

The TECRA® Unique™ Salmonella test uses the principle of immunoenrichment to allow rapid detection of Salmonellae in food. A collaborative study was conducted to compare the TECRA Salmonella Unique test with the reference culture method given in the U.S. Food and Drug Administration's Bacteriological Analytical Manual. Three food types (milk powder, pepper, and soy flour) were analyzed in Australia and 2 food types (milk chocolate and dried egg) were analyzed in the United States. Forty-one collaborators participated in the study. For each of the 5 foods at each of the 3 levels, a comparison showed no significant differences (p ≥ 0.05) in the proportion of positive test samples for Unique and that for the reference method using the Chi-square test for independence with continuity correction.
Variables Affecting Simulated Use Determination of Residual Ethylene Oxide in Medical Devices
Authors: Centola Duane T , Ayoub Kamal I , Lao Nelson T , Lu Hollington T C , Page Barry F J
Published: February 2020

In autumn 1993, AAMI/ST/WG 63, Sterilization Residuals Working Group undertook the task of studying factors involved in determining the amount of residual ethylene oxide in medical devices after sterilization and developing a protocol for controlling the relevant variables. The protocol was evaluated by conducting a round robin study consisting of 8 participating laboratories from around the country. Results of this round robin study demonstrated the range over which results may vary despite controls placed on the time and temperature at which determinations were conducted. The data from the study suggest that small, random variations in technique during short sample extraction times can lead to variability in the results. Variables such as initial water temperature, oven temperature, weighing of sample, and length of extraction should be carefully controlled. Inherent variations in the material composition of similar devices are possible contributing factors. The efforts of this working group and the subsequent evaluation and discussion of its findings are presented.
Determination of Moisture in Cheese and Cheese Products
Authors: Bradley Robert L , Vanderwarn Margaret A
Published: February 2020

Variables related to oven-drying samples of cheese and cheese products to determine moisture content were examined to provide more efficient and reproducible methods. Over 6500 samples of cheese were analyzed in an effort to modify the current AOAC procedure. The gravity atmospheric oven was unsuitable for use in accurate moisture analysis because of wide temperature differentials within the oven cavity. Use of this for oven moisture determination resulted in higher variance, which corresponded to the high temperature variation within the oven. Cheese sample preparation using an Oster blender yielded consistently lower variance in final moisture content than did preparation of cheese samples with a hand grater, rotary grater, and plug and plunger. Sample size of 3 ± 0.25 g maximized surface area-to-volume ratios and yielded a lower error in final moisture content because of better control of ambient weight loss rates. Use of combination of disposable 5.5 cm diameter aluminum sample pans with 5.5 cm diameter glass fiber filter pads for covers produced a smaller standard deviation for moisture analysis than did the AOAC pan and insert cover and filter paper covers. All pans must be pre-dried for at least 3 h at 100°C, and the glass fiber covers should be pre-dried for 1 h under the same conditions. All dried pans and covers must be stored in a desiccator with active desiccant. Equipment upgrades from the existing AOAC standard methods provide safer more efficient methods of analysis.
Determination of Phytase Activity in Feed by a Colorimetric Enzymatic Method: Collaborative Interlaboratory Study
Authors: Engelen Adrianus J , van der Heeft Fred C , Randsdorp Peter H G , Somers Wim A C , Schaefer Jan , van der Vat Bianca J C
Published: February 2020

Fourteen laboratories participated in a collaborative study (coded fyt9404) and 13 laboratories participated in a study (coded fyt9410) to validate a colorimetric assay for determination of microbial phytase activity in feed. For each study, all laboratories received 6 laboratory samples provided by one commercial supplier (phytase activity levels within the range of 200–400 per kg) to be analyzed in duplicate. Method performance was calculated and statistical calculations were executed according to AOAC guidelines. Results from 3 laboratories for study fyt9404 and from one laboratory for study fyt9410 were excluded from statistical analysis because of invalid data determined during initial review by Youden pair, value versus laboratory. For study fyt9404, repeatability relative standard deviation (RSDr) values ranged from 6.2 to 8.6%, and reproducibility relative standard deviation (RSDR) values ranged from 14.1 to 27.6%. No outliers were identified. For study fyt9410, RSDr values ranged from 3.9 to 7.9%, and RSDR values ranged from 14.0 to 20.5%. With outliers excluded, RSDr values ranged from 2.5 to 7.9%, and RSDR values ranged from 14.0 to 20.5%.
Determination of Coumarin in Fragrance Products by Capillary Gas Chromatography with Electron Capture Detection
Authors: Wisneski Harris H
Published: February 2020

A gas chromatographic (GC) method is described for the determination of coumarin in fragrance products. Coumarin was tentatively identified by retention time and confirmed by GC/mass spectrometry. The amount of coumarin was determined by external standard. The method was validated by conducting recovery studies from fortified fragrance products at several concentrations. Recoveries of coumarin ranged from 99 to 110%, with a relative standard deviation of 3.24. The method was used to survey a variety of fragrance products purchased in the metropolitan Washington, DC area, for coumarin. Seventy one percent of the products were found to contain coumarin at concentrations ranging from 0.002 to 0.61%.
GC/ITMS Measurement of Carbonyls and Multifunctional Carbonyls in PM2.5 Particles Emitted from Motor Vehicles
Authors: Rao Xin , Kobayashi Reiko , White-Morris Rochelle , Spaulding Reggie , Frazey Paul , Charles M Judith
Published: February 2020

A method was developed and tested to identify and quantitate carbonyls and multifunctional carbonyls in fine particulate matter (PM2.5; <2.5 μm aerodynamic diameter). The method relies on ultrasonic extraction of particulate matter on filters at −8°C; derivatization with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA), and PFBHA along with bis (trimethylsilyl) trifluoroacetamide (BSTFA); and detection of the derivatives by gas chromatography/ion trap mass spectrometry. Ultrasonic extraction of model compounds from enriched particles was affected by solvent polarity (water > methylene chloride > toluene–isopropanol (2 + 1, v/v). Water provided the highest recovery for dihydroxy acetone, pyruvic acid, and hydroxy acetone, compared to methylene chloride, and toluene–isopropanol. Lowering the ultrasonication bath temperature from 0° to −8°C improved the recoveries of the less water soluble and more volatile species—methacrolein, methyl vinyl ketone, 2,3-butanedione, and tolualdehyde. The power of the method was demonstrated by identification and quantitation of carbonyls and multifunctional carbonyls in sample extracts of fine particulate matter (PM2.5) collected in the Caldecott tunnel, CA. The identities of crotonaldehyde, 2,3-butanedione, glyoxal, 9H-fluoren-9-one, glycolaldehyde, glyoxylic acid, levulinic acid, and 3-hydroxybenzaldehyde were confirmed by comparing the relative retention time and mass spectra of the analyte in the sample extract with an authentic standard. Quantitation of crotonaldehyde, glyoxal, 2,3-butanedione, glyoxylic acid, and levulinic acid was accomplished. This is the first report of glyoxylic acid, levulinic acid, and 3-hydroxybenzaldheyde in PM2.5 particles sampled in a roadway tunnel. It is also the first report of a C10 carbonyl with the molecular formula of C10H16O2, a hydroxy carbonyl with the molecular formula of C17H21NO2, and a hydroxy or dihydroxy carbonyl with the molecular formula of C16H14O2 or C9H10O3. The high-molecular weight hydroxy carbonyls, which were found only in the heavy-duty (diesel) bore, may be tracers of diesel emissions in air.
Speciation of Zinc in Low Molecular Weight Proteins of Breast Milk and Infant Formulas by Size Exclusion Chromatography/Flame Atomic Absorption Spectroscopy
Authors: Bermejo Pilar , Peña Elena M , Fompedriña Diego , Domínguez Raquel , Bermejo Adela , Cocho José A , Fernández José R , Fraga José M
Published: February 2020

Size exclusion chromatography (SEC) and flame atomic absorption spectroscopy (FAAS) were used for the separation of metal-containing species in milk whey. After milk ultracentrifugation, the sample was injected into a TSK-Gel G2000 glass column and eluted with 0.2M NH4NO3–NH3, pH 6.7. Low molecular weight proteins were fractionated, and the fractions were characterized by molecular weight. Zinc distributions were obtained by FAAS using a high performance nebulizer. The method was very sensitive (limit of detection = 2.6 × 10−3 μg/mL; limit of quantitation = 8.9 × 10−3 μg/mL) and precise (RSDs ≤ 10%). This method was applied to the determination of Zn in binding compounds in breast milk whey and in commercial cow's milk-based formulas. Distribution patterns were different. The presence of Zn in most fractions in breast milk was most significant, whereas in infant formulas Zn was detected only in fractions of molecular weight <5 kDa and in the highest molecular weight peak.
Determination of Heavy Metals and Pesticides in Ginseng Products
Authors: Khan Ikhlas A , Allgood James , Walker Larry A , Abourashed Ehab A , Schlenk Daniel , Benson William H
Published: February 2020

Medicinal plants may carry residuals of environmentally persistent pesticides or assimilate heavy metals in varying degrees. Several factors may influence contaminant accumulation, including species, level and duration of contaminant exposure, and topography. As part of a program for assessment of the quality of herbal medicines, we have analyzed 21 over-the-counter ginseng (Panax ginseng) products in various dosage forms. Chromium, mercury, and arsenic were undetectable above their limits of detection in both liquid and solid samples; while cadmium, lead, and nickel were present in the majority of samples. The chlorinated pesticide levels varied widely. In most samples, the total concentration of pesticides was below 100 ppb; while in 5 samples the total concentration exceeded 100 ppb.
A Statistical Model To Evaluate Analyte Homogeneity for a Material
Authors: McClure Foster D
Published: February 2020

An underlying assumption for collaborative studies is that the analyte variation among test samples of the material (i.e., matrix and analyte concentration combination) under study has a negligible influence on the estimates of precision for the method. This assumption is expected to be fulfilled when the material under study is prepared (i.e., thoroughly mixed) such that the analyte is distributed uniformly throughout the matrix. Statistical design and intra-class correlation analysis procedures are proposed to assess the similarity oragreement among analytical results among- and within-containers for single and multiple occasions of use (e.g., collaborative and proficiency studies).
Determination of Pyrimethamine in Animal Tissue and Egg by Liquid Chromatography with Fluorescence Detection
Authors: Horii Shozo , Nishi Masatoshi , Oku Naoto , Miyakawa Hiroyuki , Tezuka Masakatsu
Published: February 2020

A sensitive and selective liquid chromatographic (LC) assay was developed to determine the concentration of pyrimethamine in animal tissue and egg by fluorescent derivative. Animal samples were extracted with acetonitrile, centrifuged, and purified by hexane. Fluorescent derivatization was performed by reacting pyrimethamine with chloroacetaldehyde and subjected to LC with fluorescence detection (excitation wavelength 300 nm, emission wavelength 420 nm). The limit of detection was 10 ng/g (10 ppb) and the standard calibration curve was linear in the range of 1–100 ppb (0.01–1 ng/10 μL). Recoveries from samples fortified at levels of 0.1 and 1 ppm (μg/g) were 61.0–77.4 and 65.5–81.2%, respectively. The method was applied to the monitoring of marketed samples. Pyrimethamine was not determined in any of the 70 samples: 20 swine muscle; 20 chicken muscle; 10 chicken liver; and 20 egg.
Determination of Organic Acids of Low Molecular Weight and Phosphate in Soil by Capillary Electrophoresis
Authors: Ahumada Ines , Mendoza Jorge , Escudero Paula , Mossert Katerina , Ascar Loreto
Published: February 2020

Capillary zone electrophoresis with indirect UV detection at 254 nm was found to be suitable for the determination of organic acids and phosphate in aqueous extracts of soil. The best support electrolyte solution was found to be 10mM p-hydroxybenzoic acid with 0.5mM tetradecyltrimethylammonium bromide to reverse electroosmotic flow. This methodology was tested with 9 analytes found in soils: acetate, citrate, formate, phosphate, lactate, oxalate, pyruvate, succinate, and tartrate. The results obtained show that the methodology is adequate for most of the analytes. The sensitivity to oxalate and citrate was low, and the high concentrations of major inorganic anions interfered with the detection of the former. The methodology was applied to the analysis of aqueous extracts of soil samples. Formate, phosphate, lactate, and acetate anions were detected in most of the samples.