氟化铵辅助消解-电感耦合等离子体质谱法测定热熔胶中7种微量元素

Determination of 7 Minor Elements in Hot Melt Adhesives by ICP-MS after Digestion Assisted with Ammonium Fluoride

建立了氟化铵辅助消解-电感耦合等离子体质谱法(ICP-MS)测定热熔胶中7种微量元素(铬、镍、砷、硒、镉、汞、铅)的方法。用由60%(体积分数)硝酸溶液6 mL和12.66 mol·L^(-1)氟化铵溶液0.50 mL组成的消解体系在185℃下微波消解0.300 0 g热熔胶样品20 min。在平板控温加热器上于120℃赶酸3 h,得到的消解液用水定容至50 mL,按优化的ICP-MS条件测定,内标元素115In用于定量。结果显示:7种元素的质量浓度与其与内标元素铟的信号强度的比值在一定的范围内呈线性关系,检出限(3s)为0.005-0.029 mg·kg^(-1);对实际样品进行3个浓度水平的加标回收试验,所得回收率为86.3%-106%,测定值的相对标准偏差(n=5)为1.8%-11%。方法用于5个实际样品的分析,在5个样品中均检出了铬和镍,3个样品中检出了铅,3种元素的检出量均低于YC/T 187-2004规定的限值;将该方法与YC/T 316-2014进行比对,在95%置信水平下,铬和镍的t值均小于临界值t0.05,4,铅的t值小于临界值t0.05,2,3种元素p值均大于0.05,2种方法无显著性差异。

A method was established for the determination of 7 minor elements(Cr,Ni,As,Se,Cd,Hg and Pb)in hot melt adhesives by inductively coupled plasma mass spectrometry(ICP-MS)after digestion assisted with ammonium fluoride.0.3000 g of samples of hot melt adhesive were digested by microwave with a selected acid mixture of 6 mL of 60%(volume fraction)HNO_(3) solution and 0.50 mL of 12.66 mol·L^(-1) NH4F solution at 185℃for 20 min.The digested solution was removed to a flat temperature control heater and heated for acid removal at 120℃for 3 h.After cooling,the solution was diluted with water and its volume was made up to 50 mL,which was analyzed under the optimized ICP-MS conditions.Internal standard element of 115In was used for qualification.The results showed that linearity relationships between values of mass concentration of the 7 elements and ratios of signal intensity of these 7 elements to interral standard element of indium were kept in the definite ranges,with detection limits(3s)ranging from 0.005 mg·kg^(-1) to 0.029 mg·kg^(-1).Recovery test was made by standard addition method,giving results of recovery in the range from 86.3%to 106%,and RSDs(n=5)of the determined values ranged from 1.8%to 11%.Five actual samples were analyzed by the proposed method,Cr,Ni were found in all the 5 samples,and Pb was found in the 3 samples,with the contents of the 3 elements below the limit specified by YC/T 187-2004.The proposed method was compared with YC/T 316-2014 by t-test,t values of Cr and Ni were less than t0.05,4,t value of Pb was less than t0.05,2,and p values of the 3 elements were all above 0.05 under the 95%confidence level.There was no significant difference between the two methods.