A fully automated spectrophotometric sequential injection titration system has been developed for the determination of carbonate and hydrogencarbonate in water samples. The sample is titrated against hydrochloric acid using phenolphthalein and methyl orange as indicators; the absorbance is measured at 430nm. A logarithmic relationship is obtained between the peak width and the absorbance. The logarithmic range for carbonate is 0.0008-0.01M, and for hydrogencarbonate is 0.001-0.01M. Reproducibility is good (<2% for carbonate and <1.5% for hydrogencarbonate) and the results obtained agree well with those obtained using a potentiometric titration. The sample throughput is 12 samplesh-1.
- Sequential injection analysis
- UV-Vis spectrophotometry
ASJC Scopus subject areas
- Analytical Chemistry
- Environmental Chemistry