Hotta Hiroki, Tsunoda Kin-ichi
Department of Chemistry, Nara University of Education.
Anal Sci. 2015;31(1):7-14. doi: 10.2116/analsci.31.7.
Recent studies from our laboratory on electrospray ionization mass spectrometry (ESI-MS) for the quantification of inorganic cations and anions are reviewed. Metal ions were determined by ESI-MS in negative-ion mode as monovalent negative ions of their aminopolycarboxylate (APC) complexes, where excess amounts of the APC agents were added to sample solutions. Among the APCs studied, we found trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CyDTA, the chemical forms in a complex were expressed as H(n)cydta(n-4)) as the best chelating agent. A size exclusion column was used for on-line separation of the metal-APC complexes from matrix salts in samples. Total amounts of Al, Ni, Cu, Zn, and Pb in the biological certified reference materials (CRM), Olive Leaves (BCR-062) and Plankton (BCR-414), and in a soil CRM (JSAC-0401) were successfully determined by the proposed method. Halide ions (X(-) = F(-), Cl(-), Br(-) and I(-)) and cyanide (CN(-)) were determined by ESI-MS based on the formation of ternary complexes of metals, chelating agents and the analyte anions. Negative ions of the ternary complexes of group 13 elements, nitrilotriacetic acid (NTA, H(n)nta(n-3)), and halides, i.e., AlF(nta) for F(-), and InX(nta) for other halides, were measured; the limits of detection (LODs) were 10 nmol dm(-3) for F(-), 0.31 μmol dm(-3) for Cl(-), 3.8 nmol dm(-3) for Br(-), and 1.6 nmol dm(-3) for I(-), respectively. In the case of CN(-), an LOD of 20 nmol dm(-3) was obtained based on measurements of the ternary complex of Cu(II), CN(-) and 4-(2-pyridylazo)resorcinol (PAR, Hnpar(n-2)), i.e., (63)Cu(II)(CN)(par) (m/z 302). Moreover, quantitative methods for Cr(VI) and Cr(III) by ESI-MS were developed, where HCrO4(-) (m/z 117) for Cr(VI) and Cr(III)(cydta) for Cr(III) were used for measurements.
本文综述了我们实验室近期关于用电喷雾电离质谱法（ESI-MS）定量分析无机阳离子和阴离子的研究。金属离子在负离子模式下通过ESI-MS测定，以其氨基多羧酸（APC）配合物的一价负离子形式存在，其中向样品溶液中加入了过量的APC试剂。在研究的APC中，我们发现反式-1,2-二氨基环己烷-N,N,N',N'-四乙酸（CyDTA，配合物中的化学形式表示为H(n)cydta(n-4)）是最佳螯合剂。使用尺寸排阻柱在线分离样品中金属-APC配合物与基质盐。通过该方法成功测定了生物认证参考物质（CRM）橄榄叶（BCR-062）和浮游生物（BCR-414）以及土壤CRM（JSAC-0401）中铝、镍、铜、锌和铅的总量。卤离子（X(-)=F(-)、Cl(-)、Br(-)和I(-)）和氰化物（CN(-)）通过ESI-MS基于金属、螯合剂和分析物阴离子形成的三元配合物进行测定。测定了第13族元素、次氮基三乙酸（NTA，H(n)nta(n-3)）和卤化物的三元配合物的负离子，即F(-)的AlF(nta)和其他卤化物的InX(nta)；检测限（LOD）分别为F(-) 10 nmol dm(-3)、Cl(-) 0.31 μmol dm(-3)、Br(-) 3.8 nmol dm(-3)和I(-) 1.6 nmol dm(-3)。对于CN(-)，基于对铜（II）、CN(-)和4-(2-吡啶偶氮)间苯二酚（PAR，Hnpar(n-2)）的三元配合物(63)Cu(II)(CN)(par)（m/z 302）的测量，获得了20 nmol dm(-3)的LOD。此外，还开发了通过ESI-MS测定Cr(VI)和Cr(III)的定量方法，其中Cr(VI)的HCrO4(-)（m/z 117）和Cr(III)的Cr(III)(cydta)用于测量。
