Open AccessApplication of an improved biuret method to the determination of total protein in urine and cerebrospinal fluid without concentration step by use of Hitachi 7170 auto‐analyzer
Author(s) -
Guobing Xu,
Lili Jiao,
Lihua Zhu,
Tiean Xia
Publication year - 2001
Publication title -
journal of clinical laboratory analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 50
eISSN - 1098-2825
pISSN - 0887-8013
DOI - 10.1002/jcla.1020
Subject(s) - biuret test , urine , spectrum analyzer , chromatography , cerebrospinal fluid , chemistry , medicine , biochemistry , computer science , urea , telecommunications
A biuret automated colorimetric assay for total protein in urine and cerebrospinal fluids was established. The procedures were as follows. Acidify all urine sample before analysis. Add precipitant Na 2 WO 4 to urine samples. After 10 min, centrifuge, decant the supernatant fluid, drain the inverted tubes on absorbent tissue, dissolve the precipitation with 0.1 mol/L NaOH, and finally adapt the reconstituted urine to the Hitachi 7170 analyzer. A cell‐free cerebrospinal fluid sample produced by centrifugation can be inserted in an auto‐analyzer for protein measurement directly. The program: mix 35 μl sample (CSF or reconstituted urine) and standard with 0.2 mol/L NaOH; incurable at 37°C for 5 min, and real A1. Add concentrated biuret reagent, and 10 min later measure absorbance A2 at 546 nm vs. reagent blank. Secondary wavelength was 700 nm. The test results were calculated against a one‐point standard. This biuret colorimetric method was relatively simple, fast, and accurate for the determination of protein in urine and cerebrospinal fluid, with a wide linearity extending from 0.125 g/L up to 6 g/L, had a good correlation with Benzethonium chloride turbidimetry technique, and was a practical routine method. J. Clin. Lab. Anal. 15:161–164, 2001. © 2001 Wiley‐Liss, Inc.