Effect of anions on atomization temperatures in furnace atomic-absorption☆

Analysis of indigenous zinc in alkaline sodic soil solutions by graphite furnace atomic absorption spectrometry

“…In contrast to Pd and HNO 3 , the presence of either NH 4 HjPO 4 or H,PO 4 increased the stability of Zn species up to 800°C (Figure 2). This is consistent with the studies of Czobik and Matousek (1977), who found that PO 4 increased atomization temperature of Zn in the graphite furnace. They attributed the increased stability of the analyte species to the greater thermal stability of Zn pyrophosphate, which is formed in the presence of H 3 PO 4 (Equation 3).…”

“…Chemical interference can be minimized by the inclusion of chemical modifiers. Czobik and Matousek (1977) examined the effect of anions on atomization temperature in furnace atomic absorption and concluded that high atomization temperatures and narrow peak-width indicate a faster rate of atom production. These investigators reported that a faster rate of atom production could also lead to a faster loss of atomic population, mainly because of increased diffusion at the higher temperature.…”

“…They attributed the increased stability of the analyte species to the greater thermal stability of Zn pyrophosphate, which is formed in the presence of H 3 PO 4 (Equation 3). Pyrophosphate formation is enhanced because H 3 PO 4 persists in the graphite furnace up to relatively high temperatures (Czobik and Matousek, 1977). 4ZnO + P 4 O 10 2Zn 2 P 2 O 7…”

“…Such interferences are often overcome by including chemical modifiers (Burrell and Guner Wood, 1969) and by optimizing the furnace parameters. For example, Matousek and Brodie (1973), Czobik and Matousek (1977), and Brodie (1985) have shown that H 3 PO 4 and NH 4 H 2 PO 4 permit a higher ashing temperature and stabilize the absorbance signal in lead (Pb) determination by the graphite furnace. Furthermore, Pd has been used as the modifier in gallium (Ga) analysis (Shan et al, 1985).…”

Mass spectral investigation of mechanisms of lead vaporization from a graphite surface used in electrothermal atomizers

“…They clearly showed that phosphoric acid allowed for the use of higher char temperatures and gave more reproducible peak areas. In later fundamental studies of phosphate addition, Czobik and Matousek (2) suggested the formation of the metal pyrophosphate as the atomization precursor, which decomposed at a high temperature to release the free metal vapor. They also reported that none of the metals studied with appearance temperatures above that of Sn (i.e., Ni and Cr) were observed at a higher temperature with the addition of phosphate.…”