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M Ihnat

Publications and source records attributed to M Ihnat.

At least 19 recordsLinked to original sources
PubMed2003

A survey of methods of analysis for minerals in feedstuffs.

A wide range of minerals occurs in feedstuffs as naturally occurring and purposely added elements, as well as by adventitious contamination. These mineral elements can generally be classified as nutritionally essential major elements, nutritionally essential minor and trace elements, and those regarded as toxic or with an essential/toxic duality. A survey is presented of methods used for the determination of major, minor, and trace elements in feedstuffs and related biological materials. Currently available methods include the following: atomic absorption spectrometry, atomic emission spectrometry, mass spectrometry, neutron activation analysis, x-ray emission spectrometry, molecular light absorption spectrometry, molecular fluorometry, electrochemistry, Kjeldahl method (nitrogen), combustion elemental analysis, volumetry, ion chromatography, and gravimetry. Available reference, routine, official, unofficial, and recommended methods are reviewed as a basis for recommendations of methods most suitable for feedstuffs.

Animal Feed↗
PubMed2001

Twenty five years of reference material activity at Agriculture and Agri-Food Canada.

In the mid 1970s, the available RMs, notably Bowen's Kale and Orchard Leaves and Bovine liver from National Bureau of Standards (NBS), although of great benefit, were overwhelmingly insufficiently representative, in respect of matrix and elemental composition, of the wide range of natural products submitted for analysis and in worldwide commerce. To provide additional coverage, an RM development project was initiated with input from cooperating analysts leading to an Agriculture and Agri-Food Canada/National Institute of Standards and Technology (NIST) cooperative venture and development of a total of 12 different agricultural/food RMs. With a total of 303 concentration values for 34 elements and a wide range of matrix components such as ash, silica, protein, fat, carbohydrate and fiber, these RMs significantly augment the world repertoire of biological control materials. A final material under consideration is a highly reliable, discrete, synthetic RM for quality control and calibration. This paper summarizes the research and developmental activities undertaken during the past quarter of a century related to RM development at Agriculture and Agri-Food Canada and includes a short historical background, conceptual considerations, preparation, physical characterization, homogeneity estimation, chemical characterization, calculation of recommended reference values and associated uncertainties, methodology development and application, and performance of inorganic analytical methods in a multielement, multilaboratory, collaborative characterization campaign.

Animals↗
PubMed1981

Silicon in plasma of sheep.

Plasma silicon (Si) concentrations were determined (i) in lambs at 49 days of age reared artificially in confinement (system A), or fed a postweaning diet, or suckled and reared conventionally (system B), (ii) in 2-year-old ewes reared under systems A and B, (iii) in lambs at 49, 70, and 100 days of age reared under system A, and (iv) in lambs (reared under system A) injected with a vitamin D3 preparation. The lambs reared under system A had a significantly lower (P less than 0.01) plasma Si concentration than did lambs reared under system B, but in ewes there was no significant difference (P greater than 0.05) between the 2 rearing systems. Plasma Si concentration of lambs increased (P less than 0.01) as the lambs aged. The vitamin D3 injection had no significant effect (P greater than 0.05) on the plasma Si value.

Age Factors↗
PubMed1980

Acid digestion, hydride evolution atomic absorption spectrophotometric method for determining arsenic and selenium in foods: Part I. Assessment of collaborative study.

Results obtained from the recent collaborative study of a hydride evolution atomic absorption spectrophotometric method for determining arsenic and selenium in foods have been studied intensively. Various parameters relating to the method have been considered: accuracy (excellent agreement between reference data and means over all laboratories for both model solutions and food samples; considerable bias for individual laboratories); precision within laboratory (repeatability coefficients of variation of 0.07-0.15) and among laboratories (reproducibility coefficients of variation of 0.13-0.28); frequency of outlying data from model solutions and biological samples (rejection rate from 9 to 29%); and detection limits (estimated as 80 and 120 ng/g for As and Se, respectively). Attempts were made to interrelate these parameters and to relate them to hydride generator characteristics and to other aspects of the procedure, namely, hydride generator type; absorbance-time peak width; standard curve slope, linearity, and precision; sample type; reagent blank magnitude; collaborator experience with sample treatment and hydride generation procedures, and departures from prescribed sample treatment procedure. On the basis of information from 28 laboratories using 16 different types of hydride generation apparatus, conducting 700 complete analyses and 2400 analyte quantitations on reagent blanks, 3 model solutions, and 13 different reference food samples with levels of As and Se ranging from 0 to 15,000 and 0 to 4,000 ng/g, respectively, the authors conclude that the method suffers from both systematic error and imprecision, and hence recommend that the method not be adopted.

Acids↗
PubMed1979

Cyanide residue levels in extracted honey, comb honey and wax cappings.

Cyanide (CN) residue levels were determined in samples of extracted honey, comb honey and was cappings at 1 hr, 24 hr, and 48 hr intervals after destroying the bees in honey bee colonies with normal (ca. 8.5 g) and twice normal (ca. 17 g) doses of CyanogasR A-dust. Applications of CyanogasR A-dust, administered by means of a dust pump at normal and twice normal doses, gave an average residue of 0.01 and 0.04 microgram CN/g of extracted honey, 0.01 and 0.02 microgram CN/g of comb honey and 0.04 and 0.06 microgram CN/g of wax cappings, respectively. When the CyanogasR A-dust (ca. 17 g) was placed on a tray and placed on the bottom board of the hive, the average residue levels for extracted honey, comb honey and wax cappings were less than 0.004, 0.01 and 0.02 microgram CN/g, respectively. Random honey samples from beekeepers, who used CyanogasR to destroy bees, had a median level of 0.031 microgram CN/g, whereas honey from a packing plant and other commercial samples contained less than 0.004--0.026, median less than 0.004 microgram CN/g. Based on residue data from this study, the temporary registration for CyanogasR, to kill honey bees after crop removal, was revised to a full registration in May 1977.

Bees↗
PubMed1977

Analysis of foods for arsenic and selenium by acid digestion, hydride evolution atomic absorption spectrophotometry.

A method based on acid digestion, hydride evolution atomic absorption spectrophotometry for estimating microgram and submicrogram quantities of As and Se in foods was developed and evaluated. Samples up to 3 g dry weight were digested with HNO3-HCIO4-H2SO4. As and Se in aliquots of the digests were reduced with NaBH4 to volatile hydrides, using laboratory-constructed and commercially available generators. As and Se were estimated by transient signal atomic absorbance measurements as the hydrides were decomposed in an Ar-H2-entrained air flame. Recoveries of inorganic As and Se added at levels of 0.1-1.0 microgram/g to a variety of foods ranged from 70 to 125%. Analyses of several standard reference samples indicated the method is capable of recovering native analytes. Detection limits for the determinative step and the method as a whole were as low as 5 and 25 ng, respectively, for both elements.

Arsenic↗
PubMed1977

Acid digestion, hydride evolution atomic absorption spectrophotometric method for determining arsenic and selenium in foods: collaborative study. tpart I.

The hydride evolution atomic absorption spectrophotometric (AAS) method for determining As and Se in foods developed and evaluated by the Food and Drug Administration and Agriculture Canada laboratories was subjected to collaborative study, Twenty-four laboratories provided results for As and 23 provided results for Se levels in 13 different samples consisting of tuna, swordfish, flounder, oyster, liver, flour, skim milk poweder, spinach, kale, and apple containing natural levels of As and Se in the ranges 0-15,000 and 0-4000 ng/g, respectively. Reference materials formed a substantial segment of samples, and a number of other laboratories using fluorometry, colorimetry, neutron activation, spark source mass spectrometry, and graphite furnace AAS provided confirmative reference values for the remaining samples. A variety of hydride generation instruments were used, ranging from commercially available devices to semiautomated and fully automated custom-made instruments. Although the accuracy of the method was fairly good, between-laboratory and between-determination (hydride evolution AAS measurement) precisions were not favorable. The main advantage of the hydride AAS method is the rapidity of the determinative step.

Arsenic↗
PubMed1976

Selenium in foods: evaluation of atomic absorption spectrometric techniques involving hydrogen selenide generation and carbon furnace atomization.

The performance of hydrogen selenide generation- and carbon furnace atomization-atomic absorption spectrometry, with a semiautomated trace metal accessory and a carbon rod atomizer, respectively, was evaluated for the determination of selenium in foods. Samples were digested with nitric, perchloric, and sulfuric acids for both procedures. Hydrogen selenide was generated with stannous chloride/potassium iodide/zinc from 20 ml aliquots in a hydrochloric-sulfuric acid medium and directed into an argon-hydrogen-entrained air flame. Sample matrix interferences in the carbon furnace technique were minimized by isolating selenium by precipitation with ascorbic acid and redissolution in nitric-perchloric acid prior to taking 5 mul aliquots for estimation; precision was significantly improved by incorporating 5000 mug nickel/ml into analytical solutions. For the hydrogen selenide and carbon furnace techniques, respectively, the following data were obtained for untreated standard solutions: sensitivity, 0.13 and 10.0 ng/ml; absolute sensitivity, 2.6 and 0.05 ng; detection limit, 0.4 and 90 ng/ml; absolute detection limit, 7 and 0.45 ng. The detection limit and absolute detection limit for samples were 2.5 ng/ml and 50 ng, respectively, for the hydrogen selenide method, and 25 ng/ml and 0.13 ng, respectively, for the carbon furnace method. Taking into consideration these figures and the practical aspects of both methods, the overall performance of the hydrogen selenide method was superior.

Evaluation Studies as Topic↗
PubMed1975

Collaborative study of a spectrophotometric method for determining maleic hydrazide residues in tobacco and vegetables.

A distillation-spectrophotometric method for the determination of maleic hydrazide residues in tobacco and vegetables reported previously was studied collaboratively. Ten laboratories submitted analytical results on 10 samples containing residues resulting either from field treatment or laboratory fortification. The samples were estimated to contain from 0.99 to 16.36 mug maleic hydrazide/0.5 g sample analyzed. The coefficients of variation based on precision standard deviation ranged from 57.7% for the lowest residue content to 32.4% for the highest. The corresponding coefficients of variation based on overall standard deviations were estimated to be at least one-fifth larger. Strong evidence of systematic laboratory differences was found (F-test, significant at 0.1%). Apparent recoveries of 10.0 mug maleic hydrazide added to 0.5 g fluecured tobacco and potato were 97.3 and 89.7%, respectively. Apparent recoveries of 16.0 and 16.5 mug added to 0.5 g green bean were 87.4 and 85.5%, respectively. The precision of the method studied was no better than that of the current official final action method, 29.121--29.127, and its adoption is not recommended.

Pesticide Residues↗