Construction and evaluation of ion selective electrodes for perchlorate with a summing operational amplifier: application to pyrotechnics mixtures analysis
R. Perez-olmos et al., Construction and evaluation of ion selective electrodes for perchlorate with a summing operational amplifier: application to pyrotechnics mixtures analysis, ANALYST, 124(1), 1999, pp. 97-100
The construction and evaluation of an electrode selective to perchlorate wi
th improved sensitivity, constructed like a conventional electrode (ISE), b
ut using an operational amplifier to sum the potentials supplied by four me
mbranes (ESOA) is described. The two types of electrodes, without an inner
reference solution, were constructed using octylammonium chloride as sensor
, a mixture of dibutylphthalate and o-nitrophenyloctyl ether as solvent med
iator and PVC as plastic matrix, the membranes being obtained by direct app
lication onto a conductive epoxy resin support. After the comparative evalu
ation of their working characteristics they were used in the determination
of perchlorate in propellants, fulminating powders and fireworks. On all oc
casions, the results obtained by the ESOA were found to be similar to those
obtained by the conventional ISE, but with higher precision. The limit of
detection of the direct potentiometric method developed was found to be 0.1
g kg(-1), and the precision and accuracy of the method, when applied to ei
ght different samples of pyrotechnic mixtures, expressed in terms of mean r
elative standard deviation and average percentage of spike recovery were 0.
4% and 100.5%, respectively. Adequate agreement was found between the resul
ts obtained by the potentiometric method and the reference methods, since t
he calculated relative errors ranged from +0.4% to -0.5%.