DETERMINATION OF PHOSPHORUS THROUGH FORMATION OF PHOSPHOMOLYBDATE COMPLEX WITH SnCl2 AND THIOUREA AS REDUCTOR BY UV-Vis SPECTROPHOTOMETRY
Yussi Pratiwi (a), Zulhipri (b), Elsa Vera Nanda (c), Aulia Natasya (d), Ayu Winani (e)

Chemistry Study Progam, Fakulty of Mathematics and Natural Science
Universitas Negeri Jakarta, Indonesia

Abstract

Analysis of phosphorus using UV-Vis Spectrophotometry method has been studied. This research aimed to get the optimum conditions for analysis of phosphorus, obtain information about the best reductor and apply this method for phosphorus analysis in vegetables which fulfills the parameters of method validation.
This research was started by determining the optimum phosphorus analysis conditions, forming a yellow complex compound. This compound was unstable, so it needed to be reduced using SnCl2 and thiourea to produce a stable blue complex. Furthermore, the phosphorus analysis was validated based on the method validation parameters.
Molybdenum blue reaction produced a heterophosphomolybdate complex compound with a maximum wavelength of 729 nm. Based on the reduction of phosphomolybdate reaction, the linearity (R2) of SnCl2 was 0.9963, while thiourea linearity was 0.9960. The molar absorptivity was 6.77 x 105 L mol-1 cm-1 and 6.94 x 104 L mol-1 cm-1 for SnCl2 and thiourea. Limit detection values of SnCl2 and thiourea were 4.37 x 10-4 mg L-1 and 7.2 x 10-3 mg L-1, respectively. The percentage of RSD in each sample ranged from 1.19 to 1.93%. Moreover, each sample^s recovery percentage ranged from 99.36% to 109.50%. The phosphates contained in the vegetable samples did not pass the food quality standard, according to the Indonesian Nutritionist Association (PERSAGI).

Keywords: phosporous, UV-Vis spectrophotometry, SnCl2, thiourea, method validation

Topic: Chemistry