Stopped-flow injection liquid–liquid extraction spectrophotometric determination of palladium in airborne particulate matter and automobile catalysts

A stopped-flow injection liquid–liquid extraction (SF-EX-FIA) spectrophotometric method is reported for the determination of palladium(II), using the 2,2′-dipyridyl-2-pyridylhydrazone (DPPH) as a color forming reagent. The colored complex Pd(II)–DPPH was extracted in CHCl3 and the absorbance was monitored at 560 nm. An injection valve was used as a commutator in order to combine the stopped-flow technique with liquid–liquid extraction FI system. The calibration graph was linear up to 12 mg l−1 (sr=0.27%; r=0.9999) with a detection limit of cL=0.007 mg l−1. The sampling rate was 20 injections per hour. The proposed method has been successfully applied to the determination of palladium in airborne particulate matter (APM) and in automobile exhaust gas converter catalysts.