DETERMINATION OF PLATINUM AND PALLADIUM IN SOIL AS THEIR CHELATES WITH N,N-DIETHYL-N′-BENZOYLTHIOUREA BY RP-HPLC

Abstract

A reversed-phase high performance liquid chromatographic (RP-HPLC) method has been developed to separate and determine platinum and palladium in soil after formation of their chelates with N,N-diethyl-N′-benzoylthiourea (DEBT). The method developed does not require the removal of the excess chelating agent and the interfering metals (i.e., Fe and Cu), before the analysis of the two metals in soil. The physical and chemical parameters affecting separation were examined in detail. The whole analysis was completed on a C18 column in 20 min, with the mobile phase of acetonitrile (ACN)-tetrahydrofuran (THF)-water (38:32:30, % v:v:v) containing 0.10 mol L⁻¹ pH 5.0 acetate buffer at a flow rate of 0.8 mL min⁻¹. Absorbance was monitored at 280 nm. Applying a salt-induced phase separation preconcentration method in combination with the proposed chromatographic method, detection limits, based on 3S_b (three times the standard deviation of the blank), were found as 0.014 mg L⁻¹ for palladium and 0.77 mg L⁻¹ for platinum using a 20-µL sample loop. Reproducibility of the method for ten repeated measurements was found as 2.36% for 0.60 mg L⁻¹palladium and 2.58% for 10.0 mg L⁻¹platinum as RSD (%). The proposed method is rapid, simple, and highly selective for the simultaneous determination of platinum and palladium in soil by HPLC.

Keywords:

• N,N-diethyl-N′-benzoylthiourea (DEBT)
• palladium
• platinum
• reversed-phase high performance liquid chromatography (RP-HPLC)
• soil

ACKNOWLEDGMENT

This research has been supported by METU Scientific Research Fund through BAP-Project No: 2002-07-02-00-40.

Notes

*RT: Room Temperature.

^a Taken as 3 s (N = 3).

^b Limit of quantitation.

^a x, Concentration of the metal ion (mg L⁻¹); y, peak area of the corresponding chelate (arbitrary unit).

^b based on 3 s.