消解方法对电感耦合等离子体原子发射光谱法测定化妆品中锑镉铬钕的影响

Study on the Effect of Methods of Digestion of Cosmetic Samples on Their Results of Determination of Antimony,Cadmium,Chromium and Neodymium by ICP-AES

比较了不同前处理方法（湿法消化、湿法回流消化和微波消化）对电感耦合等离子体原子发射光谱法测定化妆品中锑、镉、铬和钕的影响,并考察了氢氟酸对粉类化妆品消解的作用。结果表明：湿法回流消化和微波消化法适合于不同种类样品的前处理。氢氟酸可充分破坏二氧化硅晶格,是粉类化妆品中测定锑所必须的;但稀土元素与氢氟酸会生成难溶氟化物沉淀,故钕的测定不宜加入氢氟酸消解。通过充分回流消化或微波消化,在不加入氢氟酸破坏二氧化硅晶格的情况下也可以将粉类化妆品中的镉、铬和钕充分提取出来。方法的加标回收率在80.3%-118.5%范围,相对标准偏差（n=11）在4.25%-6.09%之间。

Different methods of sample pretreatment,especially ① the conventional wet digestion with HNO3 and HClO4;② the refluxing wet digestion with HNO3;and ③ the microwave assisted digestion with HNO3 and H2O2,were studied to find out their effects on the ICP-AES determination of Sb,Cd,Cr and Nd in various kinds of cosmetic samples,such as the water,emulsion,oil and powder based cosmetics.The action of hydrofluoric acid on the digestion of powder based cosmetics was also tested.The sample solutions obtained by any of the above methods were diluted to a definite volume and used for ICP-AES analysis.As shown by experimental results,digestion method ② and ③ were feasible to be used for various kinds of cosmetics.Hydrofluoric acid was necessary for dissolution of powder based cosmetics to break the crystal lattice of SiO2,especially in the determination of antimony;but it should not be used for samples containing neodymium,because insoluble fluoride precipitate of NdF3 was formed in the presence of HF.It was proved that by either the digestion method ② or ③,any of the Cd,Cr or Nd if present in the powder cosmetics could be extracted completely from the sample even without the addition of HF.Tests for recovery and precision of the proposed method were tested,values of recovery and RSD′s（n=11） found were in the range of 80.3%-118.5% and 4.25%-6.09% respectively.