Two electrothermal atomic absorption techniques which provide linear working functions over wide concentration ranges, and are suitable for the determination of zinc and copper in aqueous and 10-fold diluted blood serum matrices are evaluated. The first technique is based on modification of the furnace tube to provide a significant decrease of the atomic absorption signal when microliter and larger volumes of sample are injected. The second technique involves a delivery system capable of dispensing micro- and submicroliter sample volumes to the furnace tube. The precision of the two techniques is about 98%.