高频燃烧-红外吸收光谱法测定土壤和水系沉积物中总有机碳和有机质的含量

Determination of Total Organic Carbon and Organic Matter in Soil and Stream Sediment by High-Frequency Combustion-Infrared Absorption Spectrometry

传统重铬酸钾容量法已难以满足测定批量土壤样品中总有机碳和有机质的绿色环保要求,为有效提高检测效率,达到少用或不用有毒、有害试剂的目标,提出了题示方法。取0.050 0 g样品(已于105℃烘2 h)于陶瓷坩埚(已于1 000℃灼烧4 h)中,置于85℃恒温电热板上,滴加体积比1∶5的盐酸-水混合溶液,直至溶液停止冒泡,蒸干后于105℃恒温干燥箱中烘烤2~3 h,取出,加入0.4 g纯铁助熔剂和1.5 g纯钨助熔剂,选择高碳池分析气路,分析时间为30 s,采用高频燃烧-红外吸收光谱法测定其中总有机碳和有机质的含量。结果表明,总有机碳的检出限(3s)为0.012%,有机质的检出限(3s)为0.021%。测定了6种标准物质中总有机碳,测定值的相对标准偏差(n=12)小于5.0%,与认定值基本一致。方法用于分析20个实际样品,测定结果与NY/T 1121.6-2006中传统重铬酸钾容量法进行对比,结果表明两种方法的测定结果具有较好的一致性。

The traditional potassium dichromate volumetric method has been difficult to meet the requirements of green environmental protection for determination of total organic carbon and organic matter in batch soil samples.In order to effectively improve detection efficiency and achieve the goal of using less or not using toxic and harmful reagents,the title method was proposed.0.0500 g of sample that had been roasted at 105℃for 2 h was placed into a ceramic crucible that had been burned at 1000℃for 4 h,which was placed on a 85℃-constant temperature electric heating plate.The mixed solution of hydrochloric acid and water at volume ratio of 1∶5 was added dropwise until solution stopped bubbling.After evaporating to dryness,the sample was baked in a constant temperature drying oven at 105℃for 2-3 h,and then taken out.0.4 g of pure iron flux and 1.5 g of pure tungsten flux were added,in which total organic carbon and organic matter were determined by high-frequency combustion-infrared absorption spectrometry through high-carbon pool analysis gas path with analysis time of 30 s.It was shown that detection limit(3s)of total organic carbon was 0.012%,and detection limit(3s)of organic matter was 0.021%.Total organic carbon in 6 standard substances was determined,with RSDs(n=12)of the determined values less than 5.0%.The determined values were basically consistent with the certified values.This method was used to analyze 20 actual samples,and determination results were compared with those of traditional potassium dichromate volumetric method in NY/T 1121.6-2006.It was shown that determination results of two methods had good consistency.