To provide a measure of the total amount of exchangeable cations that can be held by peat expressed as mequiv./100 g air-dried peat, the modified method of Puustjärvi for cation exchange capacity has been proposed and studied collaboratively. The statistical treatment of the collaborators’ results indicate a satisfactory degree of precision and accuracy for the 3 products considered, moss, humus, and reed-sedge. The method for cation exchange capacity of peat materials, with the description of the transfer technique included, has been adopted as official first action. The 7 ASTM methods have been adopted as procedures.
This paper describes a simple, rapid modification of a method developed at the Fisheries Research Board of Canada for determining mercury in fish and other food products. Wet digestion and flameless techniques of atomic absorption spectrophotometry are used. Replicate analyses on different days showed good precision and samples spiked with known amounts of mercury showed adequate recovery.
Medicated feeds (pelleted or mash) containing guarantees of carbadox, furazolidone, nitrofurazone, and ethopabate are pretreated with water, extracted with 95% dimethylformamide overnight at room temperature, cleaned up on a column of alumina, and injected into a high pressure liquid chromatograph for quantitative measurement. Carbadox, nitrofurazone, and furazolidone can be separated; chromatograms show excellent baseline resolution, and results are in good agreement with colorimetric methods. The same extraction and cleanup can be used to improve colorimetric methods for furazolidone and nitrofurazone.
A liquid fertilizer containing phosphite was toxic to over 1,000 ha of corn (Zea mays L.) in southern Michigan. The fertilizer contained 9% N, 8% P, and 7.5% K and was applied over the seed at planting time. Toxicity was also obtained when the foliage was sprayed with the same fertilizer. Laboratory tests using paper chromatography and greenhouse trials identified the P source as a phosphite (HPO3)−2. Plants showed white, variegated streaking of the leaves in mild cases and spindly, rolled, yellowish‐white leaves in severe toxicity.
An empirical method for determining moisture, mineral, and organic content of peat has been proposed and collaboratively compared with a method similar to that used in Federal specifications for the purchase of peat. Moisture results were significantly low by the Federal method in all cases but generally were equally precise by both methods, indicating that larger samples do not greatly improve the precision. Ash results were about the same for both methods, although the Federal method gave higher precision; ashing conditions in the proposed method appear inconsistent due either to the lower ashing temperature or to the larger sample used. It is recommended that study be continued.
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