Determination of trace metals in sea-water by electrothermal atomic absorption spectrometry following solid-phase extraction: quantification and reduction of residual matrix effects

Abstract

The use of an iminodiacetic resin for trace metal preconcentration from sea-water does not allow a complete removal of the matrix, since significant amounts of alkali and alkaline earth elements are retained by the resin and co-elute with the analytes. The interfering effects due to sodium, potassium, calcium and magnesium on the electrothermal atomization of cadmium, lead, copper, iron and manganese were studied in a multivariate way. The adopted method allowed both an accurate quantification of the signal variations due to the matrix elements and a prediction of the analytical error in the determination by electrothermal atomic absorption spectrometry. In order to reduce the interfering effects, two different approaches were considered: chemical modification and matrix separation by pre-elution with ammonium acetate. A significant decrease of the interfering effects was observed for copper, lead and cadmium, after optimization of the thermal programs and proper choice of the chemical modifier. Differently, strong signal variations caused by the matrix were observed for iron and manganese, for each condition. Matrix separation by selective elution with ammonium acetate was more effective, allowing the complete suppression of matrix effects for all the considered elements. The results were confirmed by the analyses of the sea-water reference materials CASS-3 and NASS-5.

Determination of ultratrace elements in natural waters by solid-phase extraction and atomic spectrometry methods

“…Pyrolytic graphite-coated tubes were used. The temperature programs (Table 1) were optimized to get the highest absorbance value and maximum pyrolysis temperature without loss of analyte [38]. Integrated absorbance was measured, exclusively.…”

“…In previous work [38], the interferences due to alkali and alkaline earth elements, still present after the preconcentration step and affecting the determination by ETAAS, were evaluated and the optimal procedure to reduce them was investigated. It was verified that the residual matrix effects can be efficiently removed by selective elution with 1 M ammonium acetate, under controlled operating conditions (pH, flow rate, and time), allowing the interferencefree analysis of the eluates.…”

Crystal structure of iminodiacetic acid monomethyl ester monohydrate, C5H9NO4 · H2O

“…The presence of two close carboxylic groups makes this molecule and its derivatives excellent ion coordination agents. This property has been fully exploited in the preparation of modified polymers and resins for ion capture, both for analytical [2][3][4] or industrial uses [5,6]. In medical related sciences, iminodiacetic acid derivatives are used as solid phase supports for peptide synthesis [7] and as base for chemical libraries in combinatory chemistry [8].…”

“…The hydrogen atoms of the main residue were placed at calculated positions and refined as riding using the SHELXL-97 defaults [1], The crystal structure contains one water molecule disordered over three positions, sum of the their freely refined occupancies is 1.00 (3). The isotropic temperature factors of the three water O atoms were constrained to be equal, the water Η atoms could not be located.…”

Determination of lead by electrothermal atomic absorption spectrometry employing a novel sampling strategy of polyurethane foam impregnated with thiazolylazo-p-cresol (TAC)

“…Among various solid materials used in solid phase extraction (SPE), [1][2][3][4][5] unloaded polyurethane foam (PUF) has been widely employed to extract many organic and inorganic species from different media. [6][7][8][9][10][11] Also, PUF has been reported as a solid support for organic reagents in extraction processes of several species from aqueous solution.…”