Development of column-pretreatment chelating resins for matrix elimination/multi-element determination by inductively coupled plasma-mass spectrometry

Abstract

Chelating resins, two kinds of iminodiacetate derivatives (IDA) of cross-linked chitosan (CCS) were synthesized and investigated for adsorption capacity, matrix elimination and collection/concentration of analytes by a column pretreatment in a multi-element ICP-MS determination method. The adsorption behavior of 54 elements at the 10 ng ml⁻¹ level on chitosan derivatives in a packed mini-column was systematically examined. Almost 30 kinds of metal ions were recovered quantitatively at pH 5 with CCS–HP/IDA (cross-linked chitosan possessing N-2-hydroxypropyl iminodiacetic acid groups) column. Compared with available chitosan–iminodiacetate resin, CHITOPEARL CI-03, the recovery of the metal ions such as Cu, Pb and La is satisfactory with CCS–IDA (cross-linked chitosan possessing N,N-iminodiacetic acid groups) and CCS–HP/IDA using 2 M nitric acid as an eluent, which may be attributed to the difference of cross-linking and macroporous structure. Compared with Chelex-100, the adsorption efficiency is in the order: Chelex-100 > CCS–IDA > CCS–HP/IDA, especially in the chelating ability for alkaline earth metals. The resin with a longer spacer (CCS–HP/IDA) showed higher adsorption selectivity between heavy metal ions and alkaline earth metals at pH < 7. The separation efficiency of the major matrix cations in seawater (Na, K, Mg, Ca) has also been investigated, and matrix interference was negligible even in a seawater sample at pH 5 with CCS–HP/IDA. The recoveries of Mn at pH 5 with CCS–HP/IDA or Chelex-100 were almost 100%. However, those of Mg with each resin were 4 or 98%, respectively. The adsorption capacities of synthesized CCS–HP/IDA for Cu(II), Pb(II) and La(III) were 0.90, 0.65 and 0.34 mmol g⁻¹, respectively. Therefore, the chelating chitosan resins developed are applicable to the pretreatment of trace amounts of elements in various kinds of water samples.