A. Perezponce et al., MICROWAVE-ASSISTED VAPOR-GENERATION FOURIER-TRANSFORM INFRARED SPECTROMETRIC DETERMINATION OF CARBONATE IN WATERS, Analytica chimica acta, 358(3), 1998, pp. 235-243
A microwave-assisted vapour-generation Fourier transform infrared spec
trometric procedure is proposed for the determination of total carbona
te in waters. The method is based on the simultaneous injection of 100
mu l of sample and 300 mu l of 0.1 M nitric acid in a two-channel man
ifold with a merging zone; a coil located inside a microwave oven enco
urages the removal of CO2. The carbon dioxide is separated from the di
stilled water employed as carrier by means of gas-liquid separator and
is introduced by a nitrogen carrier flow inside a long-path infrared
absorption gas cell, from which the corresponding flow analysis record
ing is registered as a function of time in the wavenumber range 2500-2
150 cm(-1). This provides direct quantification of total carbonate con
centration in the range up to 1000 mg HCO3- l(-1) with a sampling freq
uency of 15 h(-1). This procedure has a limit of detection of 15 mg HC
O3- l(-1) and a variation coefficient of 1.3% for five independent ana
lyses of 500 mg HCO3- l(-1). Results obtained for a series of real wat
er samples compare well with those obtained using a titrimetric refere
nce method. (C) 1998 Elsevier Science B.V.