ETAAS determination of gallium in soils using slurry sampling

Abstract

For determining gallium in soils, suspensions were prepared by weighing 5-40 mg of sample and adding 5 ml of concentrated hydrofluoric acid, the suspensions being introduced directly into the electrothermal atomizer. A solution containing 0.5% m/v palladium was injected separately into the atomizer as the chemical modifier. A fast programme with no conventional ashing stage was used for the heating cycle. Calibration was carried out using aqueous standards. The detection limit was 0.25 mg g 21 . The reliability of the procedure was verified by comparing the results obtained with others based on microwave-oven sample digestion and by analyzing several certified reference materials. Relative standard deviation values of ¡1.9% for a 20 ng ml 21 standard solution and ¡2.5% for a 0.1% m/v soil suspension were obtained.

Slurry sampling for determination of lead in marine plankton by electrothermal atomic absorption spectrometry

“…Moreover, HF displayed no benefit in decreasing the background signals (Fig. 4) unlike those reported with soil and sediments [15][16][17][18][19]. The background absorption tended to increase with increasing HF concentration in the plankton slurries such that for 5% v/v HF the analyte signal was underneath that of the background (Fig.…”

“…In the former, the pyrolysis step is omitted and the drying is performed at a relatively high temperature. This approach has been applied to the analysis of siliceous samples [12,[15][16][17][18][19], coal and fly ash [14] and biological samples [24,27]. The precision and accuracy were reported to be comparable to those obtained by conventional-heating approach [14,19,25], in which high temperature ashing is performed to destroy volatile matrix components in the presence of chemical modifiers.…”

“…This approach has been applied to the analysis of siliceous samples [12,[15][16][17][18][19], coal and fly ash [14] and biological samples [24,27]. The precision and accuracy were reported to be comparable to those obtained by conventional-heating approach [14,19,25], in which high temperature ashing is performed to destroy volatile matrix components in the presence of chemical modifiers. Thus far, a number of chemical modifiers have been proposed for the stabilization of Pb during thermal pretreatment, including Ir(NO 3 ) 2 +Mg(NO 3 ) 2 in plant and sediment materials [4], Pd(NO 3 ) 2 in particulate matter [5], Pd(NO 3 ) 2 + Mg(NO 3 ) 2 in sediments [13,28], and human hair [21], NH 4 H 2 PO 4 in food samples [29], and NH 4 H 2 PO 4 +Mg(NO 3 ) 2 in plant and animal tissues [30].…”

“…Thus far, a number of chemical modifiers have been proposed for the stabilization of Pb during thermal pretreatment, including Ir(NO 3 ) 2 +Mg(NO 3 ) 2 in plant and sediment materials [4], Pd(NO 3 ) 2 in particulate matter [5], Pd(NO 3 ) 2 + Mg(NO 3 ) 2 in sediments [13,28], and human hair [21], NH 4 H 2 PO 4 in food samples [29], and NH 4 H 2 PO 4 +Mg(NO 3 ) 2 in plant and animal tissues [30]. Hydrofluoric acid [16,17,19,[31][32][33] and polytetrafluoroethylene (PTFE) [34,35] have also been used as chemical modifier in a different sense to eliminate the matrix in the analysis of slurries of siliceous samples. The effect of HF and PTFE were attributed to their fluorinating action to convert silicates to volatile silicon tetrafluoride.…”

“…Hydrofluoric acid (HF) has been also used as a suspension medium for refractory and siliceous samples [15][16][17][18][19]. Depending on analyte concentration and sample type, the concentration of slurries varies between 0.5 to 5% m/v.…”