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土壤交换性酸的测定习用滴定法,操作较繁;本文研究应用中性红比色法测定,获得了较满意的结果,方法简便快速。 一、测定方法 (一)仪器和试剂配制 72型分光光度计 2厘米比色皿 0.5NBaCl_2—0.055N TEA 溶液 称取305克结晶氯化钡(BaCl_2·2H_2O)溶于无二氧化碳的蒸馏水中,加入浓三乙醇胺37毫升和6N盐酸2毫升稀释至5000毫升,用盐酸或TEA调至pH8.0。 0.1％中性红溶液 称取0.5克中性红溶于500毫升95％乙醇中。 0.02N标准盐酸溶液 取浓盐酸1.65毫升用水稀释至1000毫升,其准确浓度用基准物质无水碳酸钠或硼砂标定。
Soil exchangeable acid determination by conventional titration method, the operation more complex; In this study, the application of neutral red colorimetric determination, obtained more satisfactory results, the method is simple and fast. First, the determination of (A) of the instrument and reagent preparation 72 spectrophotometer 2 cm cuvette 0.5NBaCl_2-0.055N TEA solution Weigh 305 g of crystalline barium chloride (BaCl_2 · 2H_2O) dissolved in carbon dioxide-free distilled water was added 37 ml of concentrated triethanolamine and 2 ml of 6N hydrochloric acid were diluted to 5000 ml and adjusted to pH 8.0 with hydrochloric acid or TEA. 0.1% neutral red solution Weigh 0.5 g of neutral red in 500 ml of 95% ethanol. 0.02N standard hydrochloric acid solution Take concentrated hydrochloric acid 1.65 ml diluted with water to 1000 ml, the exact concentration of the reference substance with anhydrous sodium carbonate or borax calibration.