The Establishment And Clinical Application Of Detection Method Of Blood Urea By Dry Chemistry

Blood urea has been a normal inspection item in examination renal function.As one of the indicators of renal function,it can sensitively reflect the renal damage in patients with diabetic nephropathy and it has great significance in diagnosis of diabetic kidney damage.The method of detecting blood urea was centered on traditional wet-chemical detection method,such as urease-Berthelot colorimetric method,two acyl oxime colorimetric method and enzyme coupling rate method.With the development of the technology of dry-chemical analysis,dry-chemical analysis has become comparable to wet-chemical analysis in determination of blood urea.Repeated experiments were carried out to develop urea strip by using dry-chemical analysis technology,and the related parameters were optimized.The optimal conditions for the development of the urea strip were as follows.The urea strip contained five layers-supporting layer,color layer,auxiliary reagent layer,filter layer and diffusion layer,and film materials of each layer were PET plate,A0.45 film,35 g/m³ film,GR blood filtration membrane and 40 mesh net gauze;Chromogenic agent was the bromine thyme phenol blue;Auxiliary reagent layer was dealt with 0.01 mol/L phosphate buffer（p H=6.5）and 0.1%Ti O₂;Enzyme concentration was 500 u/m L in solution;The quantity of sample was 15μL,the response time was 90 s.The optimal conditions for production technology were as follows.The diameter of the hole of support layer was 4 mm,dispensing parameters of input and output were set at 1.2 and 4.5,the weight of enzyme solution was between 41.4 to 43.0 mg every five drops,the temperature of the dryer was set at 45℃.The result of performance evaluation of the urea strip were as follows.The range was 1.91～55.16 mmol/L;The within-run and between-run coefficients variation of precision analysis were 3.11%～4.96%and 10.06%～14.25%,respectively;And the rate of recovery was 99.7%.Results showed that dry-chemistry method of detecting urea concentration in this paper had a good precision and high accuracy.The catalytic activity of urea strip could still maintained 82.3%of the original activity after six months,structure and activity of enzyme maintained stable for a long time.In this paper,100 whole blood samples were tested,the experiment shows that dry-chemistry method and method of automatic analyzer had good clinical equivalence for clinical analysis of urea in blood sample,and dry-chemistry method could be applied to rapid detection of blood urea in clinical.The urea strip developed in this paper had good clinical application value and market development value.