bluuebunny/crossref_metadata_2025 huggingface dataset:
7. Intertidal life
Authors: Mladenov Philip V.
Published: February 2020

The intertidal region of the Global Ocean is a thin strip of shoreline lying between the high and low tide marks; it is completely submerged by seawater at the highest high tides and completely uncovered at the lowest low tides. The intertidal region is occupied almost exclusively by marine organisms that have adapted to live in a very stressful physical environment influenced by exposure to air, temperature extremes, wind, and the pounding of waves. This region is home to a diverse and interesting marine community that is easy to study and enjoy due to its accessibility. It is also a place where people routinely harvest seafood, and is prone to a wide range of human impacts.
Protective effects of 4-aminopyridine in experimental optic neuritis and multiple sclerosis
Authors: Dietrich Michael , Koska Valeria , Hecker Christina , Göttle Peter , Hilla Alexander M , Heskamp Annemarie , Lepka Klaudia , Issberner Andrea , Hallenberger Angelika , Baksmeier Christine , Steckel Julia , Balk Lisanne , Knier Benjamin , Korn Thomas , Havla Joachim , Martínez-Lapiscina Elena H , Solà-Valls Nuria , Manogaran Praveena , Olbert Elisabeth D , Schippling Sven , Cruz-Herranz Andrés , Yiu Hao , Button Julia , Caldito Natalia Gonzalez , von Gall Charlotte , Mausberg Anne K , Stettner Mark , Zimmermann Hannah G , Paul Friedemann , Brandt Alexander U , Küry Patrick , Goebels Norbert , Aktas Orhan , Berndt Carsten , Saidha Shiv , Green Ari J , Calabresi Peter A , Fischer Dietmar , Hartung Hans-Peter , Albrecht Philipp
Published: February 2020

Chronic disability in multiple sclerosis is linked to neuroaxonal degeneration. 4-aminopyridine (4-AP) is used and licensed as a symptomatic treatment to ameliorate ambulatory disability in multiple sclerosis. The presumed mode of action is via blockade of axonal voltage gated potassium channels, thereby enhancing conduction in demyelinated axons. In this study, we provide evidence that in addition to those symptomatic effects, 4-AP can prevent neuroaxonal loss in the CNS. Using in vivo optical coherence tomography imaging, visual function testing and histologic assessment, we observed a reduction in retinal neurodegeneration with 4-AP in models of experimental optic neuritis and optic nerve crush. These effects were not related to an anti-inflammatory mode of action or a direct impact on retinal ganglion cells. Rather, histology and in vitro experiments indicated 4-AP stabilization of myelin and oligodendrocyte precursor cells associated with increased nuclear translocation of the nuclear factor of activated T cells. In experimental optic neuritis, 4-AP potentiated the effects of immunomodulatory treatment with fingolimod. As extended release 4-AP is already licensed for symptomatic multiple sclerosis treatment, we performed a retrospective, multicentre optical coherence tomography study to longitudinally compare retinal neurodegeneration between 52 patients on continuous 4-AP therapy and 51 matched controls. In line with the experimental data, during concurrent 4-AP therapy, degeneration of the macular retinal nerve fibre layer was reduced over 2 years. These results indicate disease-modifying effects of 4-AP beyond symptomatic therapy and provide support for the design of a prospective clinical study using visual function and retinal structure as outcome parameters.
Left Inferior Frontal Gyrus Integrates Multisensory Information in Category Learning
Authors: Li You , Seger Carol , Chen Qi , Mo Lei
Published: February 2020

Humans are able to categorize things they encounter in the world (e.g., a cat) by integrating multisensory information from the auditory and visual modalities with ease and speed. However, how the brain learns multisensory categories remains elusive. The present study used functional magnetic resonance imaging to investigate, for the first time, the neural mechanisms underpinning multisensory information-integration (II) category learning. A sensory-modality-general network, including the left insula, right inferior frontal gyrus (IFG), supplementary motor area, left precentral gyrus, bilateral parietal cortex, and right caudate and globus pallidus, was recruited for II categorization, regardless of whether the information came from a single modality or from multiple modalities. Putamen activity was higher in correct categorization than incorrect categorization. Critically, the left IFG and left body and tail of the caudate were activated in multisensory II categorization but not in unisensory II categorization, which suggests this network plays a specific role in integrating multisensory information during category learning. The present results extend our understanding of the role of the left IFG in multisensory processing from the linguistic domain to a broader role in audiovisual learning.
The Functional Field of View of Older Adults is Associated With Contrast Discrimination in the Magnocellular not Parvocellular Pathway
Authors: Power Garry F , Conlon Elizabeth G , Zele Andrew J
Published: February 2020

Objectives

As we age, the functional field of view (FFOV) declines and these declines predict falls and motor vehicle accidents in older adults (Owsley, C. (2013). Visual processing speed. Vision Research, 90, 52–56. doi:10.1016/j.visres.2012.11.014). To increase understanding of possible causes of this decline, the current study explored whether the FFOV in older adults is associated with the sensitivity of the magnocellular and parvocellular sub-cortical pathways.

Method

Forty-four younger (M = 27.18, SD = 5.40 years) and 44 older (M = 72.18, SD = 5.82 years) adults completed an FFOV test and the steady- and pulsed-pedestal paradigms of Pokorny and Smith (Pokorny, J., & Smith, V. C. (1997). Psychophysical signatures associated with magnocellular and parvocellular pathway contrast gain. Journal of the Optical Society of America. A, Optics, Image Science, and Vision, 14, 2477–2486. doi:10.1364/josaa.14.002477) as measures of magnocellular and parvocellular pathways, respectively.

Results

Older adults made more FFOV errors and had higher contrast discrimination thresholds in both the steady- and pulsed-pedestal paradigms, than younger adults. FFOV errors in the younger group were not related to contrast discrimination thresholds. In multiple regression, older group FFOV errors showed a strong unique association with contrast discrimination thresholds mediated via the magnocellular, but not the parvocellular pathway.

Discussion

We infer that reduced magnocellular pathway contrast sensitivity may contribute to reduced functional vision in older adults.
Distributional impact of the Malawian Essential Health Package
Authors: Arnold Matthias , Nkhoma Dominic , Griffin Susan
Published: February 2020

In low- and middle-income countries (LMICs), making the best use of scarce resources is essential to achieving universal health coverage. The design of health benefits packages creates the opportunity to select interventions on the basis of explicit objectives. Distributional cost-effectiveness analysis (DCEA) provides a framework to evaluate interventions based on two objectives: increasing population health and reducing health inequality. We conduct aggregate DCEA of potential health benefits package interventions to demonstrate the feasibility of this approach in LMICs, using the case of the Malawian health benefits package. We use publicly available survey and census data common to LMICs and describe what challenges we encountered and how we addressed them. We estimate that diseases targeted by the health benefits package are most prevalent in the poorest population quintile and least prevalent in the richest quintile. The survey data we use indicate socioeconomic patterns in intervention uptake that diminish the population health gain and inequality reduction from the package. We find that a similar set of interventions would be prioritized when impact on health inequality is incorporated alongside impact on overall population health. However, conclusions about the impact of individual interventions on health inequalities are sensitive to assumptions regarding the health opportunity cost, the utilization of interventions, the distribution of diseases across population groups and the level of aversion to inequality. Our results suggest that efforts to improve access to the Essential Health Package could be targeted to specific interventions to improve the health of the poorest fastest but that identifying these interventions is uncertain. This exploratory work has shown the potential for applying the DCEA framework to inform health benefits package design within the LMIC setting and to provide insight into the equity impact of a health benefits package.
On the Monodromy of Meromorphic Cyclic Opers on the Riemann Sphere
Authors: Alley Charles LeBarron
Published: February 2020

We study the monodromy of meromorphic cyclic $\textrm{SL}(n,{\mathbb{C}})$-opers on the Riemann sphere with a single pole. We prove that the monodromy map, sending such an oper to its Stokes data, is an immersion in the case where the order of the pole is a multiple of $n$. To do this, we develop a method based on the work of Jimbo, Miwa, and Ueno from the theory of isomonodromic deformations. Specifically, we introduce a system of equations that is equivalent to the isomonodromy equations of Jimbo–Miwa–Ueno, but which is adapted to the decomposition of the Lie algebra $\mathfrak{sl}(n,\mathbb{C})$ as a direct sum of irreducible representations of $\mathfrak{sl}(2,\mathbb{C})$. Using properties of some structure constants for $\mathfrak{sl}(n,\mathbb{C})$ to analyze this system of equations, we show that deformations of certain families of cyclic $\textrm{SL}(n,\mathbb{C})$-opers on the Riemann sphere with a single pole are never infinitesimally isomonodromic.
Effect of Dietary Lipid Oxidation on Measurement of Protein Efficiency Ratios
Authors: Lohrey Evelyn E , Hughes Ian R , Gray Ian K
Published: February 2020

Casein and lactalbumin were used to test the effect on protein efficiency ratio (PER) of variations in procedure allowable within the official AOAC method. A split plot factorial experiment was used to measure the relative effects of (1) the stage at which oil was mixed into the diets, (2) the initial peroxide value (PV) of the oil, and (3) the presence of sucrose on the PV of the dietary lipids and on PER. The effects of storage time and temperature of the experimental diets and of the addition of antioxidants on the PV of dietary lipids and on PER were also measured. Development of rancidity, measured by the PV of the extracted lipids, was shown to be about twice as rapid in casein as in lactalbumin diets. Maximum PVs of approximately 1100 and 600 were obtained for lipids from casein and lactalbumin diets, respectively. The mean PER of casein was high (3.65) when oil containing antioxidant (PV 1.2) was added last in dietary preparation, but it was significantly lower (3.10) when premixes containing antioxidant-free oils (PV 23 and 38) and sucrose were used. The lactalbumin PER was much less affected by these factors—comparable figures were 3.79 and 3.57. Under conditions favoring oxidation, lipids in the diets oxidized slowly at 5°C but rapidly at 22°C; additions of antioxidants retarded oxidation and significantly increased the PER of casein. We suggest that consistency in the PER method will be improved if dietary oxidation is controlled, and that clusters of phosphoserine in the casein molecule, chelating with iron and copper ions of the diet to form potent oxidative catalysts, may be the reason for accelerated oxidation in casein diets.
Determination of Benzo (a) pyrene in Foods
Authors: Saito Yukio , Sekita Hiroshi , Takeda Mitsuharu , Uchiyama Mitsuru
Published: February 2020

An analytical method was developed for determining benzo (a) pyrene in foods, suitable for routine use. The method consists of 4 cleanup steps: (1) alkali cleavage of sample, (2) preliminary silica gel column chromatography, (3) selective extraction with concentrated sulfuric acid, and (4) further silica gel column chromatography. Recoveries of benzo- (a) pyrene added to 50 g (or 10 g) food at levels of 0.4 ppb (or 2 ppb) ranged from 70% for short-necked clam and mackerel to 85% for chicken meat. The sulfuric acid extraction step affords a simple method for isolating benzo (a)- pyrene from various kinds of interfering substances which could not be separated by existing methods.
Asbestos-Free Method for Determining Crude Fiber: Collaborative Study
Authors: Holst David O
Published: February 2020

A rapid asbestos-free method for crude fiber analysis has been tested collaboratively in 2 studies over the past 2 years. Nine laboratories participated in the 1976 study, which included 10 feed samples with crude fiber contents ranging from 2 to 33%, and 5 laboratories collaborated in the 1977 study on 6 high protein supplement samples, of highly gelatinous material, with crude fiber contents ranging from 0.5 to 12.0%. The combined results of the 2 studies showed the following for the AOAC and the asbestos-free methods, respectively: sd 0.55 and 0.49; sr (r = random error) 0.26 and 0.22; sb (b = bias) 0.48 and 0.43; average range between independent analyses 0.29 and 0.22% crude fiber; and average maximum spread among laboratories 1.7 and 1.4% crude fiber. The asbestos-free method is precise, accurate, and capable of filtering the proteinaceous, cellulosic, or starchy gels encountered in many samples, and eliminates the use of asbestos, thereby avoiding the hazards associated with inhalation of asbestos fibers. One chemist can easily complete 60 samples per day. The asbestos-free method has been adopted as official first action.
Gas-Liquid Chromatographic Determination of Pyridazinones in Technical Products and Formulations
Authors: Cellerino Giuseppe , Re Mariarosa
Published: February 2020

Simultaneous determination of the active ingredient and of by-products in technical and formulated pyridazinones was rapidly performed by gas-liquid chromatography with complete resolution of all compounds. Quantitative determination by the internal standard technique is accurate and precise. The lower limit of detectability is 8 × 10–12 g/sec with a flame ionization detector and 1 × 10–12 g/sec with a nitrogen-phosphorus selective detector operating in the nitrogen mode.
Colorimetry of Allylisothiocyanate in Mustard Seed
Authors: Devani Muljibhai B , Shishoo Chamanlal J , Dadia Bharati K , Mody Hema J
Published: February 2020

A colorimetric method has been developed for determining allylisothiocyanate in pure samples. The procedure has been applied to the estimation of the allylisothiocyanate content of mustard seed without the preliminary distillation step. Lambert-Beer's law is obeyed in the range 25–200 μg/ml of the reaction mixture. Three mustard seed samples contained 0.823, 0.447, and 0.450% allylisothiocyanate with standard deviations of 0.017, 0.019, and 0.017%, respectively, when analyzed by the proposed method.
Colorimetric Determination of Thymol and Eugenol in Volatile Oils
Authors: Korany Mohamed A , Abdel-Salam Nabil , Abdel-Salam Mohamed
Published: February 2020

A colorimetric method for determining thymol and eugenol in volatile oils is presented. Thymol and eugenol are reacted with sodium cobaltinitrite in aqueous acetic acid. The yellow color produced is measured at 330 and 370 nm in chloroform, and at 396 and 450 nm in sodium hydroxide solution for thymol and eugenol, respectively. The method is applied to the assay of thyme oil (thymol type) and clove oil. The results obtained are reasonably reproducible with a coefficient of variation less than 2%.
Gas-Liquid Chromatographic Determination of Pentachlorophenol in Milk
Authors: Erney D Ronald
Published: February 2020

A gas-liquid chromatographic (GLC) method developed by other workers for determining pentachlorophenol (PCP) in water has been adapted for determining PCP in raw and homogenized milk. PCP is extracted from milk with benzene and from the benzene into a potassium carbonate solution. Acetic anhydride is added to the aqueous solution to form PCP acetate, which is extracted into hexane and then determined by electron capture GLC. Duplicate determinations of PCP in milk fortified at levels of 0.02, 0.2, and 2.0 ppm gave respective average recoveries of 80.0, 87.2, and 85.0%. PCP levels as low as 0.005 ppm can be detected in 20 g milk.
Handling of Volatile Alkyl Halides for Infrared Spectroscopy
Authors: Kanai Hiromitsu , Wakatsuki Helen , Inouye Veronica
Published: February 2020

A technique is described for handling volatile alkyl halide unknowns for vapor phase infrared spectroscopy. The sample vial is broken and the liquid is transferred to a screw-capped vial. The vial is placed in a large bottle containing acetone and stored in a refrigerator. For IR analysis, the sample is transferred to the special assembly.
Simple Combustion-Vapor Trapping Technique for Determination of Mercury in Fish
Authors: Teeny Fuad M
Published: February 2020

A simple combustion train was constructed for analyzing mercury in fish samples. A nitric acid trap was used to capture the mercury vapors which were released later by adding a tin salt. The method is rapid, accurate, and reproducible and permits one person to analyze 40 samples daily. Sample matrix had no apparent effect on the recovery of mercury. Mean recoveries from fish samples spiked with 0.3 and 1.0 μg mercuric chloride/g ranged from 97 to 105% with an average recovery of 101.5% and a standard deviation of 2.74%.
Proton Magnetic Resonance Spectroscopic Determination of Disulfiram: Collaborative Study
Authors: Sheinin Eric B , Benson Walter R
Published: February 2020

A proton magnetic resonance spectroscopic method for determining disulfiram in the bulk drug product and in the formulated material was collaboratively studied. The method depends on the use of chloroform-d as a solvent and hexamethylcyclotrisiloxane as the internal standard. No interference from tablet excipients was observed. The method is rapid and specific. Eighteen laboratories analyzed duplicate samples of a bulk drug product, a 250 mg tablet composite, and a 500 mg tablet composite. The average per cent results and standard deviations were 99.7±1.4, 100.9±2.0, and 99.9±2.2, respectively.
Identification of Different Crystalline Forms of Diatrizoic Acid
Authors: Folen Victor A , Schwartzman George , Maienthal Millard , Brannon Wilson L
Published: February 2020

Standard reference samples of diatrizoic acid gave 2 different infrared (IR) spectra, x-ray diffraction patterns, and differential thermal and thermal gravimetric curves. One form, the anhydrous acid, shows no weight loss when heated to 170°C. The other form, the dihydrate, loses 5.36% of its weight when heated from 86 to 144°C. The anhydrous diatrizoic acid is the preferred reference standard, because it has an IR spectrum and x-ray diffraction pattern suitable for identification purposes.
Quantitative Thin Layer Chromatographic Determination of Furazolidone and Nitrofurazone in Animal Feeds
Authors: Cieri Ugo R
Published: February 2020

A method is presented for determining the nitrofurans furazolidone and nitrofurazone in animal feeds. The sample is extracted with acetone, and aliquots of the concentrated extract are spotted on thin layer chromatographic fluorescent plates. After development in CHCl3-methanol (90+10), the bands containing the nitrofurans are detected under shortwave ultraviolet light, scraped from the plate, and extracted with ethanol. The centrifuged extracts are scanned from 500 to 300 nm on a recording spectrophotometer with a tungsten lamp, and the absorbance maxima near 360 nm are used for quantitation. To compensate for extraction and chromatographic losses and for other interferences, the nitrofuran not present in the sample is added as an internal standard. The method is generally not applicable at a level below 0.005% since detection of the bands becomes difficult.
Gas-Liquid Chromatographic Determination of Oxydemeton-Methyl in Commercial Formulations
Authors: Schronk Leonard R , Colvin Billy M , Hanks Alan R
Published: February 2020

Flame ionization gas-liquid chromatography (GLC) with a 10% DC-200 on 80-100 mesh Gas-Chrom Q column is used for the rapid determination of oxydemeton-methyl in commercial formulations. The detector response is linear for 1.0–10.0 μg oxydemeton-methyl, with a sensitivity of 4 ng. The column was stabilized before analysis by injection of a lecithin solution. Samples were diluted with chloroform and injected; peak height ratios were used for quantitation with fluoranthrene as the internal standard. Carbaryl was removed from mixed formulations by silica gel chromatography, oxydemeton- methyl was eluted with methanolchloroform (2+98), and the eluate was collected for infrared (IR) and GLC analyses. Methoxychlor and Karathane were removed by chromatography on Florisil before IR analysis. GLC results compare favorably with those for IR, with recoveries ranging from 98.44 to 102.88% for spiked formulations.
Quantitative Determination of Polysorbate 60 in Non-Standard Salad Dressings
Authors: Smullin Charles F
Published: February 2020

Six samples of non-standard salad dressing, containing 0.10 to 0.60% polysorbate 60, were submitted to 6 collaborators. The salad dressing is extracted and the extract is saponified and acidified, and the acids are removed. The aqueous, polyol solution is desalted and the polyoxyethylated polyols are precipitated as a highly insoluble heteropoly acid complex. The polysorbate 60 content is calculated from the weight of the precipitate, using a gravimetric factor. Average recoveries from the collaboration samples ranged from 105 to 130%, with standard deviations from 0.016 to 0.047. The method has been adopted as official first action.
Gas-Liquid Chromatographic Determination of Nitrate and Nitrite in Cheese, Ham, Fish Sausage, Cod Roes, and Salmon Roes
Authors: Toyoda Masatake , Suzuki Hideyo , Ito Yoshio , Iwaida Masahiro
Published: February 2020

The 2,4-xylenol method was modified and a gas-liquid chromatographic (GLC) method was developed for nitrate and nitrite determinations in several foods. Either a flame ionization (FID) or an electron capture detector (ECD) can be used. Proteins and fats are removed from warm alkaline water with zinc sulfate and filtered. The filtrate is evaporated to dryness, redissolved in water, and reacted with 2,4- xylenol in the presence of sulfuric acid to form 6-nitro-2,4-xylenol. Interfering chlorides are precipitated with silver sulfate and the nitroxylenol is extracted with hexane, concentrated, and injected. Nitrite in the nitrate is distilled at pH 5, collected in alkaline solution, and dried. The residue is oxidized to nitrate with permanganate in the presence of sulfuric acid, and then chromatographed in the same manner as nitrate. Recoveries from several foods were 83-100% for nitrate and 80-100% for nitrite. The limit of sensitivity was 0.1 ppm for both residues.
Isolation and Purification of Moniliformin
Authors: Steyn Martin , Thiel Pieter G , Van Schalkwyk Gideon C
Published: February 2020

A bulk purification procedure is described for moniliformin, a mycotoxin produced by Fusarium moniliforme. The method involves methanol extraction of suitably molded maize, aqueous extraction of the methanol-f ree residue, ion exchange chromatography with a NaCl concentration gradient, desalination, and crystallization. A pKa value of 1.70 as well as molar absorptivities of 19100 (λ(H2O)max 229 nm), 5600 (λ(H2O)max 260 nm), and 4700 (λ(MeOH)max 260 nm) L/mole/cm are reported for moniliformin.
Rapid Thin Layer Chromatographic Method for Determining Aflatoxin Bi, Ochratoxin A, and Zearalenone in Corn
Authors: Balzer Ivan , Bogdanić Čedo , Pepeljnjak Stjepan
Published: February 2020

A multimycotoxin thin layer chromatographic method is described for the analysis of corn. Aflatoxins are extracted from the samples with acetonitrile-water, and sodium bicarbonate is added to separate the acidic ochratoxin from zearalenone and aflatoxin B1. After chloroform extraction, 1/V NaOH is added to separate zearalenone and aflatoxin B1# The separated mycotoxins are spotted on TLC plates, which are then examined under ultraviolet light. The following recoveries ( % ) were obtained for corn samples: aflatoxin B1 71, ochratoxin A 87, and zearalenone 85. The limits of detection for the respective mycotoxins were 2, 40, and 200 ppb.
Determination of Zearalenone in Cornflakes and Other Corn-Based Foods by Thin Layer Chromatography, High Pressure Liquid Chromatography, and Gas-Liquid Chromatography/High Resolution Mass Spectrometry
Authors: Scott Peter M , Panalaks Thavil , Kanhere Sri , Miles Walter F
Published: February 2020

A simple cleanup procedure based on pH adjustments was used to obtain extracts of corn foods. The method gave good recoveries of zearalenone determined by thin layer chromatography (TLC) and high pressure liquid chromatography (HPLC). As little as 5 ng zearalenone was detected by TLC, using Fast Violet B Salt as the spray reagent; the lower limit of detection in cornflakes was about 20 ≧kg. With HPLC on Spherisorb silica (5 ≧m) and detection by fluorescence at an excitation maximum of 310 nm as little as 5 ≧g zearalenone/kg cornflakes could be determined. While the TLC method was also applicable to corn chips, cornmeal, popcorn, and frozen corn, an interference was observed in HPLC of the latter 3 products. This interference was separated from zearalenone by adding a second HPLC analytical column (Spherisorb ODS). Gas-liquid chromatography coupled with mass spectrometric single ion monitoring at high resolution, although of limited availability, was shown to be the most sensitive and selective method for determining zearalenone in corn foods. The natural occurrence of zearalenone in a sample of cornflakes (13–20 ≧/kg) was demonstrated by all 3 detection procedures.
Spectroanalytical Parameters of Fungal Metabolites. V. Rubratoxin B
Authors: Neely William C , Siraj Mohamed Y , Smith Libby B , Wallace Hayes A
Published: February 2020

Using ultraviolet absorption spectrometry, rubratoxin B can be quantitatively determined over the concentration range 1.0 × 10−3 to 3.8 × 10×5M in acetonitrile or p-dioxane. Fluorescence, while observable, is a practical method only with apparatus of exceptional sensitivity and low signal-to-noise ratio. The calculated mean lifetime of fluorescence is 0.211 nsec. The calculated fluorescence quantum yield is 0.058. No phosphorescence was observed for rubratoxin B. Reasonable precautions should be taken to avoid exposure of dissolved rubratoxin B to light but the solid form is relatively stable. While water hydrolyzes the anhydride ring on the toxin, the process is reversible so that subsequent analysis is possible. Rubratoxin B is relatively stable to dry oxidation, in the dark, at room temperature even on thin layer chromatographic plates where the large surface area gives maximal exposure to oxygen.
Thymidine Kinase Heterozygous L5178Y Mouse Lymphoma Forward Mutational Assay
Authors: Palmer Kenneth
Published: February 2020

The biological basis and protocol for the thymidine kinase heterozygous L5178Y mouse lymphoma forward mutational assay (TK+/−) are described. The TK+/− assay is used for the detection of mutations produced by chemicals or radiation.
Atomic Absorption Spectrometric Determination of Cyhexatin in Apples
Authors: Love John L , Patterson John E
Published: February 2020

A rapid method using atomic absorption spectrometry has been developed for determining residues of cyhexatin in apples. Each analysis takes less than 30 min and the method is sensitive to less than 0.1 mg cyhexatin/kg. Recoveries varied from approximately 100% at 0.25 and 0.05 mg/kg to 70% at 5 mg/kg. No acid digestion or cleanup is required for the analysis.
Atomic Absorption Spectroscopic Determination of Lead Extracted from Acid-Solubilized Tissues
Authors: Farris Fred F , Poklis Alphonse , Griesmann Guy E
Published: February 2020

A method is presented for determining lead in a variety of tissues. Lyophilized samples are solubilized with nitric acid at room temperature in glass screw-cap culture tubes. Following neutralization with sodium hydroxide and sodium bicarbonate, the lead is extracted into methyl isobutyl ketone as the pyrrolidine dithiocarbamate complex and analyzed by flame atomic absorption spectrophotometry. Brain, heart, liver, lung, and spleen gave recoveries ranging from 92 to 102% with standard deviations of less than 8%. Aorta, kidney, and rib were unsuitable for analysis by this method. A large number of samples can be analyzed without specialized equipment or intricate experimental steps. The detection limit is 35 ng/g tissue (wet weight) and sensitivity is approximately 140 ng/g tissue (wet weight).
Flameless Atomic Absorption Spectroscopic Determination of Heavy Metals in Whole-Fish Samples
Authors: Okuno Iwao , Whitehead James A , White Robert E
Published: February 2020

Flameless atomic absorption spectroscopy with a carbon rod atomizer was used to determine lead, cadmium, and chromium in wholefish samples. Samples were dry-ashed, and the metals were separated by solvent extraction with ammonium pyrrolidine dithiocarbamate in methyl isobutyl ketone, and then back-partitioned into an aqueous acid solution for analysis. The back-partitioning step allows a direct comparison of sample solutions with aqueous solutions of the standard. Recoveries of the metals from fortified samples averaged 91% (±9.6) for lead and 100% (±5.6) for chromium at the 0.1–1 ppm level, and 100% (±13.3) for cadmium at the 0.01–0.1 ppm level.
Gas-Liquid Chromatographic Determination of TYans-Unsaturation in Fats and Oils on Packed Columns: Effect of Positional Isomers
Authors: Conacher Henry B S , Iyengar Jagannath R
Published: February 2020

Studies in our laboratories indicated that the trans contents of a number of commercial margarines, determined by gas-liquid chromatography (GLC) on a 15 ft column packed with 10% Silar IOC, were approximately 80-85% of those determined by infrared spectroscopy. This is mainly due to overlap of some of the trans positional isomers with the cis positional isomers in the octadecenoate fraction, shown by studies involving determination of the transoctadecenoate content of the margarines by silver ion thin layer chromatography/GLC, and by preparation and study of the GLC behavior of the cis and trans positional isomers of Δ6-, Δ9-, Δ12-, and Δl5-octadecenoates. The last 3 isomers were prepared by hydrazine reduction and nitrous acid isomerization of linoleic and linolenic acids. Since it is possible that longer, more efficient columns might result in better separation of the cis- and traru-octadecenoate isomers, it is recommended that studies be continued on longer packed columns (20 ft) and possibly on support-coated open tubular columns.
Atomic Absorption Spectrometric and Colorimetric Determination of Iron in Seafoods
Authors: Gordon Dennis T
Published: February 2020

Iron levels in 14 seafoods were determined by atomic absorption spectrometry (AAS) on freeze-dried composites. Samples were prepared for analysis after dry-ashing at 550°C and wet digestion in HNO3-HCIO4. Paired analysis of wet digests were accomplished by AAS and use of the colorimetric reagent, ferrozine. There was no significant difference in iron levels of seafoods due to sample preparation. While individual species levels were not significantly different between the AAS and colorimetric procedures, evaluation of all determinations indicates that ferrozine gives lower values (P < 0.005) by 8%. Iron levels in seafoods in /tg/g dry weight (nig/100 g wet weight) determined by AAS on wet-digested samples were: 8 species of white /infish, 16.3±4.2 (0.31 ±0.08) ; Pacific shrimp, 12.3±1.4 (0.29±0.03) ; canned tuna, water pack, 16.6±2.9 (0.49±0.09); sockeye salmon, 29.0±5.5 (0.89±0.25) ; American shad, 29.1±1.5 (0.97±0.05) ; Pacific oysters, 391± 45 (6.54±1.39); and Dungeness crab, 17.1± 2.5 (0.35±0.05).
Application of the Official AOAC Cholesterol Method to a Wide Variety of Food Products
Authors: Punwar Jalam K , Derse Philip H
Published: February 2020

This paper presents fa.^iytical data on the cholesterol content of selected consumer food products including some fats and oils. The cholesterol data are grouped by food products. To determine the reproducibility of cholesterol values, recovery data were obtained from samples of pure vegetable shortening spiked at 40 and 20 mg cholesterol (as cholesteryl palmitate)/ 100 g fat. Average recoveries were 97.1% and 95.4% with coefficients of variation of 1.27 and 3.24%, respectively.
Fossomatic Method of Somatic Cell Counting in Milk: Collaborative Study
Authors: Mochrie Richard D , Monroe Robert J
Published: February 2020

Fossomatic, a fully automatic, fluoro-optoelectronic somatic cell counter, was evaluated in 6 laboratories. One set of 6 duplicate milk samples, fresh and preserved, was read with instruments as routinely calibrated to each laboratory’s direct microscopic somatic cell counts (DMSCCs), i.e., local standard. A second set was read after standardizing the instrument to a 3-sample common standard (DMSCC) shipped to each collaborator. Cell levels of the unknowns ranged from 371 to 2301 thousand (th)/ml by DMSCC, with an s per sample of 14.8% and s of a level mean of 1.8%. Fossomatic values averaged 1014 compared to 1031 th cells/ml by DMSCC, had homogeneous variance for duplicates within laboratories (s = 4.0%), and had an error per observation of 6.2%. The linear coefficient of 0.9966±0.0039 (for fresh milk and common standard) for the Fossomatic values regressed on DMSCC gave an excellent and unbiased estimate of the cell concentration in a milk sample. A small bias was evident in only 5 of 24 linear regressions (fresh or preserved within each standard) where slopes differed significantly from 1. All 5 were on values derived from a local standard with maximum biases of +18% and —28% (at a 1 million level). Preserved milk had slightly lower (P < 0.01) cell concentrations than fresh milk but only by 3.6% at 1 million. Although condition X level was significant (P < 0.01), the 6 cell levels differed by a magnitude of only 27— 45 th cells/ml. Between-laboratory variation (the component was 4.6%) and laboratory X level interaction were both significant, but their contributions to error were small. The spread in laboratories at any cell level was about 12% and the error of estimate for a sample sent to 2 laboratories was 6.8%. Although interactions were significant with this precise method, they were not of such a magnitude as to invalidate cell count estimates in practice. The Fossomatic method has been adopted as official first action.
Gas-Liquid Chromatographic Determination of Kepone Residues in Finfish, Shellfish, and Crustaceans
Authors: Carver Richard A , Borsetti Arnold P , Kamps Laverne R
Published: February 2020

Finfish, shellfish, and crustacean samples are extracted with isopropanol and benzene; the extract is filtered and then concentrated. The extract, dissolved in hexane, is treated with oleum and extracted with aqueous alkali. The aqueous phase is acidified and extracted with petroleum ether-ethyl ether (1+1). The Kepone residue is determined by electron capture gas-liquid chromatography (GLC). Recoveries obtained by 8 laboratories from 15 species of finfish fortified at 0.02-0.23 ppm ranged from 37 to 107% with a mean ± relative standard deviation of 79.4±14.5%. For oysters fortified at 0.01- 0.10 ppm, recoveries range from 63 to 129% with a mean of 78.2 ±20.8%. For crustaceans fortified at 0.05—0.26 ppm, recoveries ranged from 52 to 110% with a mean of 78.8±16.4%. The approximate limits of quantitation for finfish and for shellfish and crustaceans are 0.02 and 0.05 ppm, respectively, under the GLC conditions used in this study.
Enzymatic Digestion of Compounded Poultry Diets for Estimation of Methionine
Authors: Datta Salil C
Published: February 2020

Compounded laying diets were digested with pepsin and hydrochloric acid followed by pancreatin and pH 8.0 phosphate buffer at 4°C to estimate methionine. Biological studies on egg production were also conducted. Methionine content of a poultry diet determined analytically in the enzymatic digest agreed with the data derived biologically through egg production.
Non-Parametric Methods for Detection of Adulteration of Concentrated Orange Juice for Manufacturing
Authors: Schatzki Thomas F , Vandercook Carl E
Published: February 2020

The composition of organic constituents (total sugars, reactive phenols, total amino acids, arginine, and γ-aminobutyric acid) has been measured in a large (360 samples) selection of concentrated orange juice for manufacturing and orange pulp wash in the U.S. trade. The detection of adulteration with sugar, reducing sugars, and citric acid addition has been investigated by using non-parametric nearest neighbor classification techniques in the 4-space of log ratios of the compositions. The results show that such detection is possible with a type 1 = type 2 error rate of 1 0% for 2 0% adulteration if at least 7 samples are taken. The assumptions of such samplings are discussed.
Evaluation of Potential for Aflatoxin Occurrence on Celery, Cauliflower, Lettuce, and Taro Root Inoculated with Aspergillus flavus and A. parasiticus
Authors: Raghu Aparna , Eadie Thomas , Llewellyn Gerald C
Published: February 2020

Culture samples of lettuce, cauliflower, celery, and taro root (Colocasia esculenta) were assayed for the presence of aflatoxin after inoculation with Aspergillus flavus and A. parasiticus. Cultures of A. flavus produced both aflatoxins B1 and G1 on taro root, but produced only B1 on lettuce, cauliflower, and celery. For taro root, the percentage of aflatoxin G1 produced was considerably greater than that of B1. While A. parasiticus did produce mycelia and spores on the lettuce and taro root samples, there were no detectable levels of any aflatoxin produced. All the samples studied were successfully extracted and analyzed qualitatively and quantitatively for the presence of aflatoxin by using official AOAC thin layer chromatographic procedures. There is sufficient evidence that Aspergilli can grow on some leafy produce and one strain produced aflatoxins.
Quantitation of Added Water in Milk by Using Vapor Pressure Osmometry
Authors: Richardson Gary H , Mortensen Margaret S , Crockett Reed G
Published: February 2020

A vapor pressure osmometer (VPO) was successfully studied in 1975. An improved osmometer with greater range and temperature stability was evaluated. Repeatability on 290 mOs/kg standard solution was 289.5±1.08. The mean and standard deviation on 36 water-free milk samples was 280.5±4 compared to 280.1±3 in the previous study. Instrument data from 2 osmometers and 2 cryoscopes produced acceptable chi-square values, and the correlation coefficients between methods were better than 0.99 for samples containing 1—21% added water. In a survey involving 760 samples, more than 37% of producer samples in one cheese plant contained > 3 % added water. Additional evidence of added water in market milk samples suggests the immediate application of the VPO to help prevent milk adulteration. The vapor pressure osomometer method for quantitating added water in milk has been adopted as official first action.
Thin Layer and High Pressure Liquid Chromatographic Analysis of Celery Seed Oil
Authors: Lund Eric D
Published: February 2020

The phthalide content of celery seed oil was determined by thin layer (TLC) and high pressure liquid chromatography (HPLC). Concentrations of the major phthalides, 3-n-butyl phthalide and sedanenolide, ranged from 3 to 10%. Both commercial seed oil and seed extract could be analyzed on silica gel TLC plates with a benzene-1% ethanol solvent system. HPLC analysis, with a Durapak-Carbowax 400 column and hexane-1% isopropanol mobile phase, was suitable only for seed oil because of interference from lipids in the extract. Analysis time was about 40 min for the HPLC procedure compared with an estimated 1—1½ hr for the TLC method. The TLC procedure was preferable, however, because of its wider scope and capability for simultaneous analysis of several samples.
Determination of Water in Compound Fertilizers
Authors: Kostyrko Krystyna , Wagner Wanda
Published: February 2020

A method is proposed for determining the water content of nitrogen-potassium-phosphorus compound fertilizers. The method combines drying with methanol extraction, with or without ultrasonic comminution of the fertilizer. The total moisture content of the sample is calculated as a sum of1 that found by drying and that determined by the extraction method (residual moisture). Two methods of methanol extraction were used: extraction of the uncomminuted fertilizer sample directly in the titration vessel, or extraction of the comminuted sample by ultrasonic vibration. Water contents determined by the proposed method ranged from 0.3 to 1.7%. Standard deviations for extraction without and with comminution were 0.015 and 0.018%, respectively. Moreover, ultrasonic comminution of fertilizer increased the amount of residual water extracted by about 20% compared with other methods.
Collaborative Study of the Gas-Liquid Chromatographic Determination of Bromoxynil Octanoate in Formulations
Authors: Helfant Laurence J
Published: February 2020

The determination of bromoxynil octanoate by a gas-liquid chromatographic (GLC) method with di-n-butylphthalate as internal standard was subjected to testing by 10 collaborators. The standard deviation for bromoxynil octanoate and bromoxynil octanoate-MCPA (2-methyI- 4-chlorophenoxyacetic acid) ester formulations averaged 0.6%. While the deviation indicates that the method is statistically sound, the results were dependent upon the efficiency of the GLC column. Therefore, it is recommended that the method be subjected to continued study to further determine the GLC conditions necessary for improved method reliability.
Sample Preparation by Column Elution for Elemental Analysis of Plant Tissue
Authors: Gaines T Powell , Mitchell G Allen
Published: February 2020

A method of sample preparation based on column elution is described for the elemental analysis of plants. Plant tissue was mixed with acid-washed Celite 545, packed in a column, and eluted with 3ZV HC1. The cluate was analyzed for K, Ca, Mg, Zn, Fe, and Mn by atomic absorption spectroscopy. Values derived from column elution compare favorably with certified values for NBS Orchard Leaves reference material and dry ash values, except for Fe which was relatively low. Precision, expressed as % coefficient of variation, ranged from 0.7 to 4.4 for column elution compared to 0.7—8.7 for dry ashing. Column elution is a fast, simple technique for sample preparation that is especially suitable for a small number of samples.
Trace Analysis: A Requirement for Toxicological Research with Carcinogens and Hazardous Substances
Authors: Bowman Malcolm C
Published: February 2020

The protocol of a valid chronic toxicity experiment involving carcinogens and other hazardous chemicals will include several requirements for determining trace quantities of these compounds. Analytical procedures must provide assurance that no extraneous substances are present that could bias the results; that accurate dosages of the chemical are administered; that personnel and work areas remain free of contamination by the substances; and that the chemical and contaminated experimental material are disposed of safely. Analyses generally involve the separation of the chemical from several dissimilar substrates of varying complexity, cleanup, and quantitation by the detection system most suitable to the compound. Since there is no general agreement on the existence of a threshold level at which most carcinogens cause cancer or at which other substances produce damage, the analyst must strive for the ultimate sensitivity allowed by the state-of-the-art. Procedures have been developed for determining low ppb levels of compounds such as 2-acetylaminofluorene, benzidine, 4-aminobiphenyl, diethylstilbestrol, and estradiol in animal diet or drinking water. These procedures specify various detection systems such as spectrophotofluorescence, high pressure liquid chromatography, and electron capture gas chromatography; however, no one system is ideal for all compounds. We report a scheme for analyzing 13 compounds, in admixture, in human urine, wastewater, and environmental surveillance samples (swabs, air niters, etc.) based on electron capture gas chromatography of their pentafluoropropionyl derivatives.
Improved Automated Optical Somatic Cell Counting Method for Raw Milk: Collaborative Study
Authors: Kelley Wesley N
Published: February 2020

A collaborative study was conducted to compare the improved automated optical somatic cell counting procedure (OSCC II) with the direct microscopic somatic cell counting method (DMSCC) in raw milk. Samples were prefixed with formaldehyde and introduced into an Auto- Analyzer system. Dilution, clarification, and cell counting were performed automatically. Five collaborators participated in the study; they analyzed 48 samples in duplicate, using 2 different sampling rates. The results were compared with DMSCC counts reported by 3 different analysts. Statistical results show that the standard deviation for the DMSCC method is 0.0825 and for the OSCC II, at a sampling rate of 80/hr, 0.0434. When results are compared, the OSCC II procedure is as accurate as, and is significantly more precise than, the DMSCC method. The faster sampling rate of the OSCC II at 120/hr has some effect on precision but little effect on accuracy. The method has been adopted as official first action.
Determination of Iodide in Nutritional Beverage Products Using an Ion Selective Electrode
Authors: Miles Preston
Published: February 2020

An ion selective electrode procedure is described for the precise, accurate determination of iodide at the sub-ppm level in a variety of nutritional beverages. The relative standard deviation of the analysis is 1-4%; recoveries range from 90 to 120%. Comparison with results from neutron activation analysis and the traditional Sandell-Kolthoff procedure shows that the ion selective electrode procedure is free of determinant error and that dry ashing of samples can lead to low results.
Gas-Solid Chromatographic Procedures for Determining Acrylonitrile Monomer in Acrylonitrile-Containing Polymers and Food Simulating Solvents
Authors: Brown Margaret E , Breder Charles V , Mcneal Timothy P
Published: February 2020

A gas chromatographic method is described for acrylonitrile monomer (AN), using a nitrogen/phosphorus detector. Procedures for the analysis of AN in 5 food simulants (water, 3% acetic acid, heptane, 50% ethanol, and 8% ethanol) as well as in the polymer matrix are included. The quantitation limit for direct injection of AN/food simulant solution is 0.04 ng AN/μl. AN-based polymers are dissolved in N,N-dimethylacetamide and injected directly. Residual AN in the polymer can be quantitated at the 0.5 ng/μl level. Results of migration studies are also presented.
Separation Testing of Hemodialysis Shunts Using Dynamic and Static Forces in a Controlled Environment
Authors: Mack George D , Smith William M
Published: February 2020

Analytical methods are presented for determining the longitudinal dynamic and static forces needed to overcome the transverse frictional forces and effect the separation of hemodialysis shunt connections under controlled environmental conditions. Results for different types of shunts and their associated connectors are reported along with the factors that affect the separation force and separation times.