The transient extension (TEx) chamber was developed to provide a simple means of lengthening an electrothermal vaporizer (ETV) signal for the purpose of obtaining a full mass scan from a single ETV firing with inductively coupled plasma mass spectrometry (ICPMS) detection. The TEx chamber was used for quantitative analysis of natural water (NIST SRM 1640). Quantitative analysis was done for Co, Be, Pb, Sb and Cd. Detection limits for the five elements tested with the TEx chamber were in the 1-10 mug L-1 range when monitoring 256 masses during a single ETV firing. In general, there was no significant change in the analyte signal using palladium, sodium chloride or magnesium nitrate modifiers when comparing results with and without the TEx chamber.