ANALYSIS OF PHOSPHORUS USING AMMONIUM MOLIBDATE WITH THIOUREA AND HIDRAZIN SULPHATE AS REDUCTORS BY USING UV-Vis SPECTROPHOTOMETRY METHOD
Yussi Pratiwi (a), Zulhipri (b), Baiq Amelia Riyandari (c), Ayu Winani (d), Adelia Nisrina (e)

(a)(b)(d)(e) Chemistry Study Progam, Faculty of Mathematics and Natural Science
Universitas Negeri Jakarta, Indonesia

(c) Department of Chemistry Education, Faculty of Education and Teacher Training
Universitas Islam Negeri Mataram, 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 thiourea and hydrazin sulphate 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 689 nm. Based on the reduction of phosphomolybdate reaction, the linearity (R2) of thiourea was 0.9960, while hydrazine linearity was 0.9954. The molar absorptivity was 6.94 x 105 L mol-1 cm-1 and 8.6317 x 104 L mol-1 cm-1 for thiourea and hydrazin sulphate. Limit detection values of thiourea and hydrazin sulphate were 7.2 x 10-3 mg L-1 and 4.83 x 10-4 mg L-1, respectively. The percentage of RSD in each sample ranged from 1.08 to 1.40%. Moreover, each samples recovery percentage ranged from 98.03% to 107.30%. 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, thiourea, hydrazine sulphate, method validation

Topic: Chemistry