Sample work-up for graphite furnace atomic-absorption spectrometry using continuous flow extraction

Abstract

Using a flow injection analysis system a two-stage extraction method has been developed to extract metals automatically from aqueous solutions; cadmium, copper, iron, lead, nickel and zinc could be concentrated 25-30-fold without serious losses. However, cobalt gave only a 15-fold enrichment. The metals are concentrated into an aqueous solution totally free from the original matrix. The flow-rate of extract is about 200 pi min-1, making the system compatible with the graphite furnace.

On-line sample pre-treatment systems interfaced to electrothermal atomic absorption spectrometry†

“…The sample plug from any on-line sample processing system might be directly collected at a fixed time in autosampler cups [25][26][27] or carried to flow-through cells 25,[28][29][30] located in a fixed position in the carousel of the ETAAS autosampler. The flow cells, also called 'well-samplers', with a capacity of 50-100 ml, are continuously filled from the bottom, and excess liquid is withdrawn at the top by gentle suction by one of the channels of the peristaltic pump.…”

“…However, there are not many papers in the literature dedicated to this subject. Bäckström and co-workers 27,36,37 spent some years developing on-line extraction systems specially designed for coupling with ETAAS, all based on the formation of hydrophobic complexes between trace metals (Cd, Co, Cu, Fe, Ni, Pb and Zn) and dithiocarbamates, which are extracted into an organic phase. Owing to their high volatility, the direct injection of these compounds into the furnace is not suitable for ETAAS determinations.…”

A comparative study of available procedures for cobalt sample preparation and introduction into atomic spectroscopic instruments

“…The determination of Co frequently involves liquid-liquid extraction. In 1984, Backstrom et al [31] quantified this metal in the presence of Cd, Cu, Fe, Pb, Ni, and Zn by continuous extraction with Freon 13 following the formation of the respective dithiocarbamate complexes; they obtained an enrichment factor of 15. Cobalt was detected by graphite-furnace AAS.…”

Determination of Nickel after Online Sorbent Preconcentration by FI-FAAS Using Dimethylglyoxime as a Complexing Agent

“…Various methods of preconcentration of analytes prior to determination with FAAS or GFAAS, based on solvent extraction (2), chelating ion exchangers (3)(4)(5), coprecipitation (6,7), and sorbent extraction (8), have been developed. The methods based on solvent extraction and coprecipitation are tedious and time-consuming.…”