Determination of Minor Nutrients in Fertilizers by Atomic Absorption Spectrophotometry: Second Collaborative Study

The atomic absorption method studied last year was re-examined and extended to include calcium and sodium. The procedures were submitted to 16 collaborators for determination of Ca, Cu, Fe, Mg, Mn, Na, and Zn. Results for Ca and Na were discouraging; further study is recommended.

Rapid Visual Technique for Recovery of Mold from Beverages and Therapeutic Liquids

A visual method is presented that enables the analyst to isolate clumps of mold from dark solutions and from colored and irregular bottles and to examine the material microscopically. The solutions to be examined are passed through a glass tube for visual examination, and any observed extraneous material is deposited directly onto a slide. Physical characteristics are not altered, and all visible mold clumps can be accurately counted and measured.

Automatic Flame Photometric Determination of Potassium in Fertilizers. A. Elimination of Anion Exchange Cleanup. B. Using Direct Available P2O5 Extract

Three primary standard grade potassium salts, eight Magruder check samples, and 18 commercial fertilizer samples were analyzed by three methods. Primary standards gave an average recovery of 100.0% and an average range of 0.21% K20. Magruder check samples averaged 0.09% K20 higher by the modified flame photometric method than the grand averages of the STPB results on the respective Magruder reports. The modified flame photometric method averaged 0.02% K20 lower than the official flame photometric method and 0.11% K20 higher than the official STPB method on 18 commercial fertilizer samples. The automatic flame photometric method, without anion exchange cleanup, is rapid enough for routine analysis and is as accurate and precise as the AOAC official methods. The method was also applied to the direct available P205 extract. Results on three primary grade potassium salts, seven Magruder check samples, and 13 commercial fertilizer samples were as accurate and precise as the official STPB method.

Gas Chromatographic Determination of Phenolic Pesticides and Residues

Polar phenolic pesticides often tail badly when direct gas chromatography is attempted. Rapid conversion of the phenolic group to the corresponding methyl ether eliminates tailing. Chromatography of DNOC, DNOSBP, ioxynil, and bromoxynil have been performed by this procedure. Determination of DNOC, DNOSBP, and ioxynil in agricultural samples is reported.

An Improved Method for Cleanup of Brassica for Parathion Analysis

An improved cleanup procedure has been developed for the recovery of parathion from crops, with special reference to cole crops. Parathion is separated from many chlorinated hydrocarbon pesticides that could cause interfering gas chromatographic responses. Electron capture techniques were used to detect the chlorinated hydrocarbon pesticides, and colorimetry and electron capture were used to determine parathion.

A Rapid Method of Carbon Analysis for Biological Materials

An induction furnace and a gasometric analyzer have been adapted for the analysis of carbon in biological materials. Samples for analysis must not exceed 70 mg carbon. The number of analyses which can be routinely performed for carbon in an eight-hour day has been increased from 8, by wet combustion, to 50, by the induction furnace method. Hay, concentrate, dried feces, wet feces, milk, and urine have been analyzed by this method with iron, cupric oxide, molybdenum trioxide, and silicic acid used as reagents. Silver phosphate and vanadium pentoxide were required to obtain satisfactory analyses of dried milk. Liquid urine was analyzed successfully by the same methods employed for dried samples except for minor modifications of the combustion tube and catalysts. Analyses on sodium carbonate, glucose, and potassium hydrogen phthalate yielded carbon recoveries of essentially 100%.

Extraction of Aflatoxin from Peanut Products by Dialysis

The dialysis with aqueous methanol of aflatoxin in natural materials has been examined. With the use of aqueous methanol of decreasing strength every two hours, high toxin values are obtained as compared with those obtained by a Soxhlet extraction with methanol. This is possibly because of partial destruction of the toxin by heating in the Soxhlet extraction.

Modification of the USP Chemical Method for Determining Vitamin D in Evaporated Milk

The USP XVI chemical method for vitamin D in USP products has been substantially modified and applied to evaporated milk containing approximately 30 units of vitamin D per fluid ounce. A major modification is a 15 second reading at 500 mμ which most nearly represents the vitamin D content of the sample. An improved sample preparation eliminates much of the background interference, which also produces a color reaction. This method, when applied to a variety of samples, will show a relative standard deviation of 10%. Statistical data are presented to compare the modified method with the rat bioassay method for assaying vitamin D in evaporated milk.

An Improved Raney Catalyst Powder Method for Determination of Nitrogen in Fertilizers

With a Raney catalyst powder containing 10% Co, 40%; Ni, and 50% Al, nitrates are reduced to ammonia in 8N sulfuric acid in 10 minutes. Neither chlorides nor organic nitrogen compounds interfere with the reduction, and the reduction passed Youden’s ruggedness test. Results of analyses of fertilizers for total nitrogen that included reduction with the powder were in good agreement with those of accepted methods.

Activation Analysis of Drugs

Activation analysis has been employed to compare and determine the source of manufacture of drugs. The irradiations were carried out with the DASA-TRIGA1 and Naval Research Laboratory nuclear reactors,2 and the induced radionuclides were identified by nondestructive gamma-ray spectrometry. The results show that the technique can be a useful tool for the identification of trace elements which serve to characterize drugs.