Simultaneous Determination of Platinum and Rhodium by

Chem. Anal. (Warsaw), 49, 793 (2004)
Simultaneous Determination of Platinum and Rhodium
by Adsorptive Stripping Voltammetry (AdSV)
with Semicarbazide**
by Sylwester Husza³, Joanna Kowalska*, Ewa Chmielewska
and Jerzy Golimowski
Faculty of Chemistry, Warsaw University,
ul. Pasteura 1, PL-02-093 Warsaw, Poland
Key words:
platinum, rhodium, semicarbazide, adsorptive stripping voltammetry
A very sensitive adsorptive stripping voltammetry procedure at a hanging mercury drop
electrode, coupled with a hydrogen catalytic reaction, for the simultaneous determination
of traces of platinum and rhodium has been proposed. Optimum conditions of the determination were as follows: accumulation potential –0.8 V, preconcetration time 60 s, scan rate
20 mV s-1. The linear relation between the analyte concentration and the height of analytical
signal was observed up to 400 ng L-1 and 500 ng L-1 for platinum and rhodium, respectively.
After 30 s of accumulation the sensitivities of 1.4 nA µmol L-1 and 2.1 nA µmol L-1 for
platinum and rhodium, respectively were observed. The detection limit (3σ of the blank)
was 0.5 ng L-1 for platinum and 0.2 ng L-1 for rhodium. The effect of potentially interfering
ions has been studied. The optimised method was successfully applied to the determination
of platinum and rhodium in real sample (hydroponically cultivated Indian mustard plant).
Prezentowana praca dotyczy oznaczania œladowych zawartoœci platyny i rodu metod¹ woltamperometrii z adsorpcyjnym zatê¿aniem, po³¹czonej z reakcj¹ katalitycznego wydzielania
wodoru na powierzchni wisz¹cej elektrody rtêciowej. Optymalne warunki oznaczania to:
potencja³ zatê¿ania –0,8 V, czas zatê¿ania 60 s, szybkoœæ polaryzacji 20 mV s-1. Wysokoœæ
sygna³u analitycznego zale¿a³a liniowo od stê¿eñ obu analitów nie wiêkszych ni¿ 400 ng L-1
(platyna) i 500 ng L-1 (rod). Czu³oœæ metody wynosi³a odpowiednio (po 30 s zatê¿ania):
1,4 nA µmol L-1 dla platyny i 2,1 nA µmol L-1 dla rodu. Granica wykrywalnoœci (3σ dla
œlepej próby) wynosi³a 0,5 ng L-1 i 0,2 ng L-1 odpowiednio dla platyny i rodu. Sprawdzono
wp³yw obecnoœci ró¿nych jonów na przebieg oznaczeñ woltamperometrycznych. Zoptymalizowan¹ metodê zastosowano do oznaczenia zawartoœci platyny i rodu w próbce rzeczywistej
(hydroponicznie uprawianej gorczycy bia³ej).
* Corresponding author. E-mail: [email protected]
** Dedicated to Professor J. Heyrovsky on the occasion of 45th Anniversary of his Nobel Prize.