Analytical Methods for Diethylstilbestrol in Feeds and Premixes

1966 ◽  
Vol 49 (5) ◽  
pp. 895-898
Author(s):  
Loyal R Stone
Keyword(s):  
Acetic Acid ◽  
Analytical Methods ◽  
Sodium Acetate ◽  
Buffer System ◽  
Official Method ◽  
Sodium Acetate Solution ◽  
Acetate Solution ◽  
Acid Buffer System ◽  
Acetic Acid Buffer

Abstract Methods are presented in which diethylstilbestrol is extracted from feeds in the Goldfisch apparatus, transferred into alkaline sodium acetate solution to avoid emulsions, and measured colorimetrically in a sodium acetate-acetic acid buffer system. The procedure is rapid, and results agree closely with those obtained by the official method. Procedures are also presented for determination of diethylstilbestrol in molasses and fat mixtures.

175. The precipitation of the proteins in milk. I. Casein. II. Total proteins. III. Globulin. IV. Albumin and Proteose-peptone

1938 ◽  
Vol 9 (1) ◽  
pp. 30-41 ◽  
Author(s):  
Samuel J. Rowland
Keyword(s):  
Acetic Acid ◽  
Total Protein ◽  
Trichloroacetic Acid ◽  
Sodium Acetate ◽  
Acetic Acid Solution ◽  
Acid Mixture ◽  
Sodium Acetate Solution ◽  
Acetate Solution ◽  
Maximum Precipitation ◽  
Proteose Peptone

Improved methods have been evolved for the separation of the total protein, casein, albumin, globulin, and proteose-peptone substances of milk.I. The use of acetic acid-sodium acetate solutions for the precipitation of casein is elucidated, and it is shown that the maximum precipitation of casein is rapidly effected from milk samples of varying casein content by the addition to 10 ml. of milk of about 80 ml. of water at 40° C. and 1·0 ml. of 10% acetic acid solution, followed, after 10 min., by 1·0 ml. of N sodium acetate solution.This maximum precipitation was found to be 1·0–1·4% greater than by Moir's method, and 2·4–3·8% greater than by the method of the Association of Oflicial Agricultural Chemists.A procedure is suggested for the determination of casein which avoids the tedious transfer and washing of the precipitate, and gives enhanced ease, accuracy and speed of working.II. The advantages of trichloroacetic acid for the precipitation of proteins in determinations of the total protein and the non-protein nitrogenous substances of milk are discussed.The trichloroacetic acid methods at present in use are shown not to give complete precipitation, and for this a rapid method employing, at room temperature, a final concentration of 12% acid in the milk-acid mixture is recommended.III. An accurate method for the precipitation of globulin uncontaminated with either albumin or casein is described.IV. Methods are given for the precipitation and separation of the albumin and proteose-peptone substances.

scholarly journals A Method for Determination of Cystine in Urine

1970 ◽  
Vol 16 (5) ◽  
pp. 366-369 ◽  
Author(s):  
Peter Haux ◽  
Samuel Natelson
Keyword(s):  
Amino Acid ◽  
Sodium Acetate ◽  
Sodium Acetate Solution ◽  
Acetate Solution ◽  
Amino Acid Analyzer

Abstract A procedure is described for the assay of cystine in urine. Cystine is ad-sorbed on a column of Dowex-50 resin at pH 2, which is then washed with water and eluted with sodium acetate solution. Color is developed with 1,2-naphthoquinone-4-sulfonate. Homocystine does not interfere in the reaction. Routine reproducibility in the laboratory was ±10.3% (2 SD) for 24 normal urines, which contained 8 to 86 mg cystine per 24 h (those values falling within 2 SD). Mean recovery was 94.5%. In two cases in which the results were compared with those obtained with the amino acid analyzer, the method was indicated to be valid for screening urine to detect cystinuria

scholarly journals Determination of Niacin in Infant Formula by Solid-Phase Extraction and Anion-Exchange Liquid Chromatography

2001 ◽  
Vol 84 (3) ◽  
pp. 789-804 ◽  
Author(s):  
Denis E LaCroix ◽  
Wayne R Wolf ◽  
Eural Porter ◽  
Dennis Cantellops ◽  
G William Chase ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Liquid Chromatography ◽  
Solid Phase Extraction ◽  
Anion Exchange ◽  
Infant Formula ◽  
Sodium Acetate ◽  
Solid Phase ◽  
Phase Extraction ◽  
Acetic Acid Buffer

Abstract A peer-verified, solid-phase extraction (SPE)/anion exchange liquid chromatographic method is presented for the determination of niacin in milk-based and soy-based infant formula. Analysis is in 3 steps: test sample digestion, extraction/cleanup, and liquid chromatography (LC). Digestion uses a standard AOAC digestion procedure that involves autoclaving at 121°C for 45 min in (1 + 1) H2SO4 to free endogenous niacin from protein and to convert added niacinamide to niacin. The digest solution is adjusted to pH 6.5 with 7.5M NaOH. Acidification to pH <1.0 with (1 + 1) H2SO4 precipitates the protein. The clarified solution is then filtered, and the filtrate is brought to volume. SPE of niacin is accomplished by passing an aliquot of the digest solution through an aromatic sulfonic acid–SPE (ArSCX–SPE) column. After the column is washed with methanol and water to remove extraneous material, the niacin is eluted with 0.25M sodium acetate/acetic acid buffer at pH 5.6. An anion-exchange polystyrene–divinylbenzene column with 0.1M sodium acetate/acetic acid buffer at pH 4.0 is used for LC. Niacin is determined by UV detection at 260 nm. A standard curve is prepared by passing known amounts of niacin through the ArSCX–SPE columns used for niacin extraction. The following values for x_bar and relative standard deviation (RSD) were obtained for National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1846 Infant Formula with a certified value for niacin of 63.3 ± 7.6 μg/g: Submitting laboratory.— x_bar = 59.7 ± 4.0 μg/g; RSD = >6.7%; confidence interval (CI) = ± 1.4 μg/g; n = 27. Peer laboratory.— x_bar = 56.6 ± 6.6 μg/g; RSD = >11.7%; CI = ± 4.1 μg/g; n = 8.

scholarly journals Experience in Validation of Methods for Determination of Radiochemical Impurities in Radiopharmaceuticals

2020 ◽  
Vol 10 (4) ◽  
pp. 244-256
Author(s):  
A. O. Malysheva ◽  
G. E. Kodina ◽  
E. A. Lyamtseva ◽  
N. A. Taratonenkova ◽  
A. S. Lunev
Keyword(s):  
Silica Gel ◽  
Analytical Methods ◽  
Experimental Studies ◽  
Sodium Acetate Solution ◽  
Acetate Solution ◽  
Technetium 99M ◽  
Sodium Pertechnetate ◽  
Validation Of Methods ◽  
Validation Parameters

Most important quality attributes of any radiopharmaceutical (RPh) are its radiochemical purity (RCP) or content of radiochemical impurities (RCIs) that have to comply with respective norms and limits. However, at present, there is no unified approach to validation of analytical methods in the context of highly radioactive samples.The aim of the study was to develop an approach to validation of methods for determination of RCI content in RPhs.Materials and methods: the authors determined the content of RCIs in a radiopharmaceutical formulation containing a complex of technetium-99m and methylenediphosphonic acid by the radiometric method after isolation of impurities from the main compound by thin-layer chromatography using silica gel and methyl ethyl ketone (for sodium pertechnetate determination) and silica gel and 13.6% sodium acetate solution (for determination of hydrolysed reduced technetium-99m). The radioactivity was registered by a chromatogram scanner with a detector of gamma-rays with energies from 0.05 to 1.5 MeV.Results: the paper analyses existing official approaches to validation of analytical procedures and compares them with the results of experimental studies described in available publications. It assesses the validation parameters for compliance with the acceptance criteria set forth in the current regulations and substantiates selectivity of chromatographic determination of impurities under the selected test conditions. Coefficients of variation for repeatability, reproducibility, and accuracy did not exceed 4.5, 2.8, and 8.9%, respectively, given the relative error of not more than 10.5%. The study demonstrated signal linearity for the 10-fold dilution of the standardised sodium pertechnetate solution, it also demonstrated correspondence between the applied and detected radioactivity when performing the test in the impurity content range of 0.5–5%. The validation procedure was associated with significant radiation burden for the personnel of the quality control laboratory.Conclusions: the authors suggested a methodological approach to validation of methods for determination of RCI content in technetium-99m-based RPhs. This approach may be used in the development of a guideline on validation of analytical methods for RCP/RCI determination in RPhs, or for introduction of relevant sections into existing documents.

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