Wen Bei

Is palladium or palladium–ascorbic acid or palladium–magnesium nitrate a more universal chemical modifier for electrothermal atomic absorption spectrometry?

A comprehensive comparison was made between the performances of Pd, Pd–ascorbic acid and Pd–Mg(NO3)2 for the determination of Ag, As, Au, Bi, Cd, Ga, Ge, Hg, In, Mn, Pb, Sb, Se, Sn, Te and Tl in terms of charring temperatures available, characteristic mass values, background absorption, permissible interference range, capability of improving the atomization signal shapes and relative standard deviations of the determinations of trace elements in real samples. Generally, the performances of Pd, Pd–ascorbic acid and Pd–Mg are similar, except that the background absorption of the Pd–Mg modifier is 1–2 orders of magnitude greater than that of the Pd and Pd–ascorbic acid modifiers. Therefore, the need for the addition of ascorbic acid appears to be matrix-dependent, while the addition of Mg(NO3)2 is not recommended.

Influence of organic amendments on the sorption of pentachlorophenol on soils

The influence of pH on the sorption of pentachlorophenol (PCP) onto three organic amendments, char, humic acid (HA) and peat, and the effect of organic amendments on PCP sorption to three kinds of soils were evaluated. The sorption of PCP on these sorbents fitted the Freundlich model well, suggesting that PCP sorption isotherms were nonlinear with exponential coefficient (N) value lower than 1. The PCP sorption capacity on three organic amendments and the N values increased with decreasing pH. The sorption capacities were in the order: char > HA > peat. Organic amendments resulted in an enhancement of sorption capacities of soils. The N values of PCP sorption on soils were decreased by char amendment and increased by HA and peat amendments. This study demonstrated that application of traditional organic amendments led to the enhancement of PCP sorption by soils. This information may aid both in predicting environmental fates of hydrophobic ionizable organic compounds and in developing remediation strategies for them.

Determination of gallium in coal and coal fly ash by electrothermal atomic absorption spectrometry using slurry sampling and nickel chemical modification

A method was developed for the determination of gallium in coal and coal fly ash by electrothermal atomic absorption spectrometry using slurry sampling and nickel chemical modification. In the presence of nickel modifier the integrated absorbance for gallium was improved by a factor of 2.46 and matrix interferences with the absorption signals were eliminated, and hence similar atomization profiles were obtained for gallium in slurries and in aqueous standard solutions. Therefore, calibration using aqueous standards could be applied. The recommended method was applied to the determination of gallium in real samples. The data obtained by slurry sampling were in good agreement with the certified values or with those obtained after pressure attack of the samples. The relative standard deviations for ten replicate determinations were in the range 2.1–5.7% for gallium in coal and coal fly ash for gallium concentrations of 1.05–59.7%µg g–1.