Abstract A stabilized-temperature plat form furnace/atomic-absorption spectrophotometric(STPF—AAS) method has been developed for the determination of tin leached from lead/tin-soldered copper pipes. The method involves the use of a modifier composed of diammonium hydrogen phosphate, magnesium nitrate and nitric acid. Aqueous tin standards in the composite matrix modifier are used for calibration. The characteristic mass and detection limit (three standard deviations of the blank) for peak-height measurement of tin are 5 pg and 1.7 μgl., respectively. The corresponding peak-area values are 26.8 pg and 12.8 μgl., respectively. The accuracy, precision, and interferences (especially of sulphate) have been assessed.