p-Chlorophenol present in various Clofibrate preparation was on determined by colorimetry, using a quantitative method for phenolic OH. This method is based on the widely used technique for colorination of indophenol, modified and adapted for phenolic OH in p-chlorophenol. As a result, a large difference was found in the commercial products of 11 companies. It does not seem that serious trouble will occur even in the product containing highest concentration of p-chlorophenol, but considering high toxicity of p-chlorophenol, it had better be as low a concentration as possible.

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The phenoldisulfonic acid method used for the measurement of nitrate-nitrogen in natural water is precise and has a good reproducibility, but the reaction of phenoldisulfonic acid with nitrate-nitrogen has not been clarified as yet. Spectrophotometric characteristics of the product from this reaction and optimal conditions for this test method were examined. The infrared absorption spectrum of the reaction product exhibits absorptions for NO₂, OH, and SO₃H. The nuclear magnetic resonance spectrum of the product indicated the presence of two H in meta position. The ultraviolet absorption spectrum indicated that this product is o-nitrophenol. From these spectral evidences, it was concluded as follows : 1) The product of reaction between phenyl-2, 4-disulfonic acid and nitrate-nitrogen is 6-nitrophenol-2, 4-disulfonic acid. 2) 6-Nitrophenol-2, 4-disulfonic acid produces an isosbestic point at 365 mμ with the addition of potassium hydroxide solution and the coloration becomes constant in alkalinity of above pH 6.5. 3) The solution colored by the addition of potassium hydroxide to 6-nitrophenol-2, 4-disulfonic acid shows stable absorption even when allowed to stand for a long time in day light. 4) Ammonia-nitrogen and cyanate ion do not interfere in the reaction of phenoldisulfonic acid and nitrate-nitrogen. Interference of nitrite-nitrogen can be removed by the addition of sulfaminic acid and that of sulfur ion by the addition of lead acetate.

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Micro-determination of nitrazepam was carried out. Nitrazepam solution was first made alkaline (pH 9-11) with 20% sodium carbonate solution and extracted with ethyl acetate by mechanical shaking. The ethyl acetate solution was then extracted with 10% hydrochloric acid, also by mechanical shaking, and the acid solution was heated at 100° for 15 minutes to effect hydrolysis. The product of hydrolysis, 2-amino-5-nitrobenzophenone, was colored by the Bratton-Marshall method and absorbance of the colored solution was measured at 535 mμ. This colorimetric determination was applicable to various samples containing nitrazepam, its recovery from the aqueous solution (91±5%) and urine (91±4%) was good, and showed good sensitivity, detection being possible in the range of 2-20 μg/ml concentration. Color of the azo pigment formed from N-(1-naphthyl) ethylenediamine dihydrochloride was stable, and it was considered that this method can be applied as a rapid and reliable determination of nitrazepam in forensic chemistry.

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The paper electrophoretic method to identify synthetic drugs difficult to separate by Stas-Otto method (antipyrine salicylate, theobromine and sodium salicylate, caffeine and sodium salicylate, caffeine and sodium benzoate, and pyrabital) and related compounds (barbital, phenobarbital, allobarbital, amobarbital, cyclobarbital, hexobarbital, antipyrine, aminopyrine, acetanilide, phenacetine, acetylsalicylic acid, caffeine, theophylline, and theobromine) was investigated by using M/30 Na₂HPO₄, 5N formic acid, 3% aqueous ammonia, 1% borax, and 10-fold diluted solution of Atkins-Pantin buffer (pH 10) as the electrolyte. The mobilities of the compounds were expressed relative to flavianic acid. It was found that synthetic drugs could be identified by using 3% aqueous ammonia and 5N formic acid as the electrolyte, and all related compounds, except acetanilide, phenacetine, and caffeine, could be separated and identified by selecting the above-mentioned electrolytes.

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