A novel off-line coupling of capillary electrophoresis (CE) and inductively coupled plasma mass spectrometry (ICPMS) is reported here. The coupling interface is based on the connection of a separation capillary to a deposition capillary via a liquid junction maintaining high separation efficiency and sample utilization due to the self-focusing effect and lack of pressure-induced flow in comparison with nebulizer-like interfaces. The separation is recorded in the form of droplets of CE effluent on a suitable substrate--a poly(ethylene terephthalate) glycol (PETG) sample plate placed inside a partially evacuated chamber. Substrate-assisted laser desorption (SALD) is used to vaporize the sample fractions and to enable further transfer to the ICPMS. The mechanism of SALD is examined using model samples deposited on a variety of substrates. The highest response is obtained for a PETG substrate; sample desorption due to ablation of PETG is found to outweigh direct ablation of sample. Detection limits are given for several metal elements. Finally, a rapid (2.5-min), high-resolution separation of Cr(III)/Cr(VI) species injected in subpicomolar quantity is shown.

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Abstract. White blood cell (WBC) count is considered a prognostic risk factor in acute myeloid leukemia. As density of leukemic cells increases, the cytotoxic activity of certain anticancer drugs, such as vincristine and doxorubicin, progressively decreases. In this study, we investigated the cell density-dependent induction of apoptosis of human acute myeloid leukemia U937 and ML-1 cells by disulfiram (DSF), the dithiocarbamate drug recently proposed for treatment of human cancers. This effect is dependent on uptake of extracellular copper and its intracellular accumulation. Highdensity cells cannot uptake and accumulate this metal to a sufficient level that would allow induction of apoptosis due to progressive decrease of its extracellular concentration. Simple addition of copper can resume sensitivity of highdensity leukemic cells to DSF and improve efficiency of antileukemic therapies using this drug, thus providing benefit to patients with high WBC count.