Exploration Of Analyzing Methods Of 20 Harmful Trace Elements In Coal By Inductively Coupled Plasma-mass Spectrometry

In this study,a method was established for the determination of 20 kinds of harmful trace elements content in coal samples,Hg,Be,Co,Ni,Cu,Pb,Mo,Sn,Sb,Tl,Th,U,Ba,Cd,B,Se,As,Ga,Zn,Cr,by ICP-MS and using the closed Teflon digestion technology.The method has the advantages of low detection limit,wide measuring range,good precision,simple and easy operation,low cost,and suitable for batch sample analysis.Methods digestion was carried out in three steps,namely 0.2g solid NH₄HF₂,1m L H₂SO₄ and 3mL HNO₃.The amount of reagent is low,the acidity of solution is low,the stability is good,and the result is reliable.Pretreatment of coal samples with solid NH₄HF₂,a series of complex chemical reactions occurred between NH₄HF₂ and coal samples under high temperature and high pressure,resulting in the swelling of samples.H₂SO₄ played a key role in the digestion of high organic matter coal samples.The sample pretreatment process is easy to operate,the sample consumption is less,the discharge is low and the cost is saved.The pretreatment method saves energy,reagent and sample consumption,cuts down the secondary pollution and reduces the loss of the element to be measured.Compared with the pretreatment method of microwave digestion,the pretreatment method with Teflon digestion tank has the advantages of low cost,high efficiency and large batch measurement.At the same time,the results of digestion can fully meet the requirements of determination.Inductively coupled plasma mass spectrometry has low detection limit,and can be used for high sensitivity and rapid determination of various elements,thus greatly improving the work efficiency.Using the reliability of the standard material verification method of coal national first grade,the relative error between the determination result and the standard value is within 10%,most of the elements are within 5%.The result is within the allowable error range of the standard value,which meets the requirements of the analysis of the trace elements of the geological samples.The precision of the 12 samples measured at12 times was less than 5%.The method is stable and reliable.