Alternative method for measurement of albumin/creatinine ratio using spectrophotometric sequential injection analysis.
A simple, automatic and practical system for successive determination of albumin and creatinine has been developed by combining sequential injection analysis (SIA) and highly sensitive dye-binding assays. Albumin detection was based on the increase in the absorbance due to complex formation between albumin and eosin Y in acidic media. The absorbance of the complex was monitored at 547 nm. For the creatinine assay, the concentration of creatinine was measured by reaction with alkaline picrate to form a colored product which absorbs at 500 nm. The influences of experimental variables such as effects of pH, reagent concentration, standard/sample volume and interferences were investigated. Under optimal conditions, the automated method showed linearity up to 20 mg L(-1) for albumin and 100 mg L(-1) for creatinine. The 3 sigma detection limits were 0.6 and 3.5 mg L(-1) for albumin and creatinine, respectively, and the relative standard deviations (n=10) were 2.49% for 20 mg L(-1) albumin, and 3.14% for 20 mg L(-1) creatinine. Application of the proposed method to the direct analysis of urinary samples yielded results which agreed with those obtained from the Bradford protein assay and a creatinine enzymatic assay according to a paired t-test. The results obtained should be a step towards developing a fully automated and reliable analytical system for clinical research, which requires direct determination of albumin and creatinine and/or its ratios.
Siangproh
Weena
W
Department of Applied Chemistry, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392, Japan. weena@swu.ac.th
Teshima
Norio
N
Sakai
Tadao
T
Katoh
Shuji
S
Chailapakul
Orawon
O
D000418:Albumins / Q000737:chemistry; D000419:Albuminuria / Q000652:urine*; D000818:Animals; D002417:Cattle; D003404:Creatinine / Q000737:chemistry / Q000652:urine*; D004801:Eosine Yellowish-(YS) / Q000737:chemistry; D017022:Flow Injection Analysis / Q000379:methods*; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D012972:Sodium Hydroxide / Q000737:chemistry; D013053:Spectrophotometry; D016482:Urinalysis / Q000379:methods*
D000418:Albumins; D005456:Fluorescent Dyes; D012972:Sodium Hydroxide; D003404:Creatinine; D004801:Eosine Yellowish-(YS)