The determination of penicillins and chlortetracycline in premixes and mixed feeds

1964 ◽  
pp. 74-95
Author(s):  
Stanley E. Katz ◽  
Kenneth Helrich
Keyword(s):  
Mixed Feeds

Fluorometric Determination of Chlortetracycline in Mixed Feeds

1964 ◽  
Vol 47 (2) ◽  
pp. 203-208
Author(s):  
Stanley E Katz ◽  
Joseph Spock
Keyword(s):  
Ion Exchange ◽  
Exchange Resin ◽  
Ammonium Hydroxide ◽  
Solvent System ◽  
Ion Exchange Resin ◽  
Alkaline Degradation ◽  
Fluorometric Determination ◽  
Mixed Feeds ◽  
Microbiological Assays

Abstract The fluorometric procedure for chlortetracycline in mixed feeds is based upon the degradation of chlortetracycline in alkaline solution to isochlortetracycline. The fluorescence of the isochlortetracycline is directly proportional to the concentration of chlortetracycline present prior to alkaline degradation. Chlortetracycline is extracted from mixed feeds with an acidmethanol solvent system, separated from the feed extract by adsorption on a Dowex 50 ion exchange resin, and eluted from the resin by ammonium hydroxide after conversion to isochlortetracycline. The isochlortetracycline is measured fluorometrically. Recoveries from known feeds are generally greater than 90% and agreements with microbiological assays are very close.

The Use of Large Samples in the Determination of Vitamin A in Mixed Feeds Fortified with Dry Vitamin A Supplements

1960 ◽  
Vol 43 (1) ◽  
pp. 25-28
Author(s):  
F Howard Tinkler ◽  
Joseph B Hanley ◽  
Robert W Lehman
Keyword(s):  
Vitamin A ◽  
Large Samples ◽  
Mixed Feeds

Automated Nitrogen Method for Feeds

1973 ◽  
Vol 56 (5) ◽  
pp. 1096-1105 ◽  
Author(s):  
Charles W Gehrke ◽  
Larry L Wall ◽  
Joseph S Absheer
Keyword(s):  
Hydrogen Peroxide ◽  
Copper Metal ◽  
Wet Digestion ◽  
Automated Method ◽  
Large Numbers ◽  
Mixed Feeds ◽  
Empirical Standard ◽  
Representative Samples ◽  
Corn Grain

Abstract A totally automated method for the determination of nitrogen in feeds has been developed. The apparatus consists of Technicon Auto-Analyzer modules. The SOLIDprep Sampler II has been interfaced with the continuous digestor to provide complete solubilization and digestion of dry samples of feed, grain, and forage materials. Hydrogen peroxide is used as an aid for the wet digestion in the continuous digestor. Mercury, selenium, or copper metal catalysts were not effective for increasing the recovery of nitrogen during the continuous digestion. Nitrogen recoveries of 88–90%, relative to ammonium sulfate, have been obtained on several materials, i.e., corn grain, wheat, barley, rice, alfalfa, fescue, mixed feeds, and feed concentrates. The recoveries from these materials average about 100±2% when an empirical standard, soy hydrolysate, is used. The system operates at 20 samples/hr and has provided precise and accurate nitrogen analyses on collaborative samples. Other laboratories cooperated with us in evaluating the method by providing representative samples and their Kjeldahl analyses. This method provides a significant reduction in the labor required for large numbers of nitrogen analyses in feeds.

Colorimetric Determination of Procaine Penicillin in Mixed Feeds

1965 ◽  
Vol 48 (4) ◽  
pp. 702-704
Author(s):  
Loyal R Stone
Keyword(s):  
Chemotherapeutic Agents ◽  
Colorimetric Determination ◽  
Procaine Penicillin ◽  
Acid Reagent ◽  
Mixed Feeds ◽  
Colorimetric Procedure

Abstract Procaine penicillin is determined by a rapid colorimetric procedure based on conversion of penicillin to penicillamine which turns blue with arsenomolybdic acid reagent. The presence of other antibiotics and chemotherapeutic agents in the feed does not interfere. The method is suitable over the range 10–100 g procaine penicillin per ton of feed.

Simplified Fluorometric Determination of Chlortetracycline in Mixed Feeds

1971 ◽  
Vol 54 (4) ◽  
pp. 947-950
Author(s):  
Stanley E Katz ◽  
Carol A Fassbender ◽  
Donald Dorfman
Keyword(s):  
Optical System ◽  
Ammonium Hydroxide ◽  
Microbiological Assay ◽  
Emission Wavelength ◽  
Fluorometric Determination ◽  
Mixed Feeds

Abstract The procedure described is based upon the alkaline conversion of Chlortetracycline to the corresponding isochlortetracyclines. The isochlortetracyclines fluoresce with equivalent intensity at the same activation and emission wavelength. Direct dilution of feed with ammonium hydroxide to levels similar to microbiological assay concentrations, the use of a feed matrix to eliminate problems of fluorescence interference from feeds, and a sensitive optical system permit the simplified assay of feeds at levels as low as 25 g/ton. Agreement with the microbiological assay is good.

Fluorometric Determination of Chlortetracycline in Low Level Mixed Feeds

1964 ◽  
Vol 47 (6) ◽  
pp. 1157-1161
Author(s):  
Stanley E Katz ◽  
Joseph Spock
Keyword(s):  
Ion Exchange ◽  
Sodium Carbonate ◽  
Fluorometric Determination ◽  
Aqueous Sodium ◽  
Exchange Column ◽  
Aqueous Sodium Carbonate ◽  
Ion Exchange Column ◽  
Low Levels ◽  
Mixed Feeds

Abstract The fluorometric determination of low levels of chlortetracycline in mixed feeds is based upon the separation of the chlortetracycline on a Decalso ion exchange column after extraction from the feed. The chlortetracycline is eluted from the resin after conversion to isochlortetracycline by hot aqueous sodium carbonate. The isochlortetracycline is measured fluorometrically. Results agree with microbial assays.

Methods for the Determination of Milk Solids in Mixed Feeds

1928 ◽  
Vol 11 (3) ◽  
pp. 410-417
Author(s):  
A B Davis
Keyword(s):  
Mixed Feeds ◽  
Milk Solids

The determination of nitrofurazone in mixed feeds

1955 ◽  
Vol 6 (9) ◽  
pp. 556-558 ◽  
Author(s):  
Jean E. Dixon
Keyword(s):  
Mixed Feeds

Liquid Chromatographic Determination of Unbound and Acetone-Soluble Bound Gossypol in Cottonseed Meals and Mixed Feeds

1992 ◽  
Vol 75 (5) ◽  
pp. 815-823
Author(s):  
Nickos A Botsoglou
Keyword(s):  
Chromatographic Determination ◽  
Gradient Elution ◽  
Liquid Chromatographic Method ◽  
Relative Standard ◽  
On Line ◽  
Liquid Chromatographic Determination ◽  
Mixed Feeds ◽  
Liquid Chromatographic ◽  
Hydrolysis Of

Abstract A liquid chromatographic method has been developed for the determination of unbound and acetone- soluble bound gossypol in cottonseed meals and mixed feeds at levels of 0.5 ppm. The method involves extraction with aqueous acetone in the presence of ascorbic acid, hydrolysis of the "soluble bound" forms with hydrochloric acid, partitioning into chloroform, and chromatographic separation on a 10 µm C18 column by step gradient elution using a methanol-water mobile phase acidified with phosphoric acid. With minor modifications, the method permitted discriminate determination of unbound gossypol and acetone-soluble hydrophilic and lipophilic forms of bound gossypol. The gossypol peak was characterized by on-line spectral scanning and absorbance rationing. Overall relative standard deviation was 6.7% and overall recovery was 98.1 ± 3.3%. When the method was applied to several cottonseed meal samples, results were inconsistent with those obtained by the official American Oil Chemists' Society method for "free" gossypol determination.

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