Spectrophotometric Determination of Low Levels of the Orthophosphate Anion as Molybdenum Blue using Sodium Thiosulphate Reducing agent
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Date
2020
Journal Title
Journal ISSN
Volume Title
Publisher
Oriental Journal of Chemistry
Abstract
A simple spectrophotometric method for the determination of low levels of the orthophosphate
(PO4
3-) in environmental water systems is reported. The method is based the formation of the
phosphomolybdate from the condensation of molybdate and orthophosphate in aqueous acid medium
followed by reduction with sodium thiosulphate to form phosphomolybdenum blue. The system obeys
Beer’s law at 880 nm (λmax) in the 0.005–0.06 mg P mL-1 phosphate concentration range. Molar absorptivity,
Sandell’s sensitivity and correlation coefficient values for the determination were 57526 L mol-1 cm-1, 0.2835
μg cm-2 and 0.9948 respectively. The limit of detection was 2.213 x 10-3 mg P mL-1. The results of PO4
3-
determination in water samples obtained using the spectrophotometric method developed in this study,
compare favourably with those generated using the Murphy and Riley method which is commonly used
for this analysis. Therefore, the study ably demonstrates the suitability of the present spectrophotometric
method for analysis of the orthophosphate in environmental water samples.
Description
Keywords
Spectrophotometric, Phosphomolybdate, Molybdenum blue, Orthophosphate anion, Sodium thiosulphate
Citation
NALUMANSI, I., BIRUNGI, G., MOODLEY, B., & TEBANDEKE, E. Spectrophotometric Determination of Low Levels of the Orthophosphate Anion as Molybdenum Blue using Sodium Thiosulphate Reducing agent. Oriental Journal of Chemistry. http://dx.doi.org/10.13005/ojc/360608