Cj. Rademeyer et al., PERMANENT IRIDIUM MODIFIER FOR ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY, Journal of analytical atomic spectrometry, 10(10), 1995, pp. 739-745
The suitability for chemical modification of a pure metal layer, depos
ited on the inner surface of a graphite tube by cathodic sputtering of
Ir in a low pressure Ar discharge, was investigated. The characterist
ics of the deposited layer were studied using scanning electron micros
copy and compared with those of Ir deposited from solution. The analyt
ical performance of the modifier was assessed in the determination of
Cd, Mn, Pb, Se and V. When sufficient Ir was deposited by sputtering,
a homogeneous layer covering the entire tube surface was formed which
changed only slightly during the entire lifetime of the graphite tube.
Thus integrated absorbance remained essentially constant for more tha
n 700 atomizations. The volatile elements Cd, Pb and Se were thermally
stabilized in the absence of a matrix to 800, 1200 and 1400 degrees C
, respectively. The rate of atomization for Mn and V was, however, unf
avourably delayed in the Ir-coated tubes.