Direct analysis of solids for trace elements by combined electrothermal furnace/quartz T-tube/flame atomic absorption spectrometry

Abstract

The analysis of solid samples by a combined graphite-furnace/air-acetylene flame technique based on generally available atomic absorption instrumentation is described. Samples are injected into the furnace and atomized via a slotted T-tube in the flame. Non-specific absorption is greatly reduced compared to that obtained in graphite-furnace atomic absorption spectrometry (a.a.s.). Sensitivity is reduced by 10–200 times compared to the direct graphite-furnace method, so that large sample sizes (up to 0.2 g) can be used; this minimizes problems caused by sample inhomogeneity. The elements considered are cadmium, lead, copper, arsenic, cobalt, mercury, antimony and selenium. Volatile elements such as mercury and arsenic can be determined without the need for a char step. Simple calibration procedures are possible in some cases and the precision is usually better than 10%. Background reduction capabilities are compared with those of conventional graphite-furnace a.a.s., the isothermal-furnace and the hollow graphite T-tube techniques. Analytical capabilities and results are presented for the direct determination of trace elements in numerous biological and some geological samples.