| 摘要 |
A composition for detecting and estimating urea in, e.g. blood, comprises urease, a pH indicator and a buffer. Specified indicators are phenol red, bromsulphalein (phenol tetrabromphthalein disodium sulphonate), nitrazine, metacresol blue, bromthymol blue, bromcresol purple and in combination phenol red and bromthymol blue. Specified buffers are of phosphate, citrate and hexamate type. Other additives may be present including algin and protective, thickening, wetting agents and inert background dyes. In examples, test strips are prepared by applying a urease/buffer/algin composition to cellulose strips, dipping the thus treated strips into an indicator solution, drying, and treating with ethyl cellulose as described in Specification 911,181 in relation to glucose oxidase compositions. The examples also describe the preparation of multiple area strips in which various areas are impregnated with compositions of different buffer concentration. These strips are prepared as described in Specification 867,192. |
