Extraction-atomic absorption spectrophotometric determination of palladium as its anionic complex with a sulfonated azo dye

The use of 3-hydroxy-4-( 1 H -tetrazol-5-ylazo)-2,7-
naphthalenedlsulfonlc acid (T-azo-R) as a complexlng agent
for the separatlon of palladium from rhodium, platinum, or
iridium by solvent extraction in the presence of benzalkonium
chloride (BACl) has been investlgated. After reextraction with
perchlorlc acid from organic to aqueous phase, palladium can
be determined by alr-acetylene flame atomic absorptlon
spectrometry (FAAS), by means of a calibration curve prepared
with commerclal standard solutions. The mutual or
matrix interferences, whlch make difficult the direct FAAS
determlnatlon of palladium in the presence of other platinum
group metals or even of some other common ions, are completely
overcome. At the same time, preconcentrations of at
least a factor of 50 can be obtained. The method has been
applied to the determinatlon of palladium and rhodium content
in two pharmaceutlcai processing sludges.