Oxalate determination in urine using an immobilized enzyme on sorghum vulgare seeds in a flow injection conductimetric system

Journal of the Brazilian Chemical Society

UNICAMP, Campinas, Brazil¹  Kubota, Lauro Tatsuo¹  Tubino, Matthieu¹  Godinho, Oswaldo Espirito Santo¹  UNESP, Bauru, Brazil¹  Oliveira Neto, Graciliano de¹  Fernandes, João Roberto¹ 

关键词: flow injection;    oxalate oxidase;    oxalate determination;    enzyme immobilization;    Sorghum vulgare;    conductimetry;   

DOI  :  10.1590/S0103-50531997000100009

学科分类：化学（综合）

来源: SciELO

【 摘 要 】

A flow-injection (FI) method was developed for the determination of oxalate in urine. It was based on the use of oxalate oxidase (E.C. 1.2.3.4) immobilized on ground seeds of the BR-303 Sorghum vulgare variety. A reactor was filled with this activated material, and the samples (200 µL) containing oxalate were passed through it, carried by a deionized water flow. The carbon dioxide produced by the enzyme reaction permeated through a microporous PTFE membrane, and was received in a water acceptor stream, promoting conductivity changes proportional to the oxalate concentration in the sample. The results obtained showed a useful linear range from 0.05 to 0.50 mmol dm-3. The proposed method, when compared with the Sigma enzymatic procedure, showed good correlation (Y = 0.006( + 0.016) + 0.98( + 0.019)X; r = 0.9995, Y = conductivity in µS, and X = concentration in mmol dm-3), selectivity, and sensitivity. The new immobilization approach promotes greater stability, allowing oxalate determination for 6 months. About 13 determinations can be performed per hour. The precision of the proposed method is about + 3.2 % (r.s.d).

【 授权许可】

Unknown