On-line ion-exchange preconcentration and determination of traces of platinum by electrothermal atomic absorption spectrometry

Abstract

A method to determine trace amounts of platinum in different samples based on electrothermal atomic absorption spectrometry is described. The preconcentration step is performed on a chelating resin microcolumn [1,5-bis(2-pyridyl)-3-sulfophenyl methylene thiocarbonohydrazide (PSTH) immobilized on an anion-exchange resin (Dowex 1x8-200)] placed in the autosampler arm. The combination of a peristaltic pump for sample loading and the atomic absorption spectrometer pumps for elution through a selection valve simplifies the hardware. The peristaltic pump and the selection valve are easily controlled electronically with two switches placed in the autosampler, which are activated when the autosampler arm is down. Thus, the process is fully automated without any modification of the software of the atomic absorption spectrometer. Under the optimum conditions with a 60-s preconcentration time, a sample flow rate of 2.4 mL min(-1), and an injection volume of eluent of 40 microL, a linear calibration graph was obtained in the range 0-100 ng mL(-1). The enrichment factor was 14. The detection limit under these conditions is 1 ng mL(-1), and the relative standard deviation (RSD) is 1.6% for 10 ng mL(-1) of Pt. The method has been applied to the determination of platinum in catalyst, vegetation, soil, and natural water samples. The results showed good agreement with the certified value and the recoveries of Pt added to samples were 98-105%.

Development of sensitive determination method for platinum in geological materials by carbon slurry sampling graphite furnace atomic absorption spectrometry

“…For this reason a separation/ preconcentration stage is often applied to remove matrix interferences and preconcentrate the analyte to a level at which it can be reliably determined. Various preconcentration approaches, such as: ion exchange [4,6,9,10,13], precipitation and coprecipitation [4,13], extraction techniques [4,[13][14][15][16][17][18][19][20][21][22] and biosorption [13,23] have been described in the literature for platinum separation from environmental samples. However, one of the most useful preconcentration treatments is adsorption onto solid adsorbents.…”

“…The determination of trace levels of platinum in geological materials requires the application of very sensitive analytical techniques, such as graphite furnace atomic absorption spectrometry (GFAAS) [3][4][5][6][7][8][9][10], inductively coupled plasma atomic emission spectrometry (ICPOES) [3][4][5]9,11], inductively coupled plasma-mass spectrometry (ICPMS), neutron activation analysis (NAA) or adsorptive voltammetry (AdV) [3][4][5]. It is worth mentioning that platinum occurs in geological materials at low concentrations and its distribution is nonhomogeneous [1].…”