Combur10 Test COBAS

Combur10 Test COBAS

1. Summary

   • Urine test strips are used to measure certain constituents in urine which are significant of renal, urinary, hepatic and metabolic disorders.

2. Test principle

   • Leukocytes (LEU)
     • These esterases cleave an indoxyl ester, and the indoxyl so liberated reacts with a diazonium salt to produce a violet dye. Bacteria, trichomonads or erythrocytes present in the urine do not affect the reaction
   • Nitrite (NIT
     • The test is based on the principle of the Griess test and is specific for nitrite. The reaction reveals the presence of nitrite and hence indirectly nitrite-forming bacteria in the urine by a pink-to-red coloration of the test patch. Even a slight pink coloration is indicative of significant bacteriuria
   • pH
     • : The test paper contains the indicators methyl red, phenolphthalein and bromothymol blue and reacts specifically with H + -ions. The most frequent pH values of fresh urine from healthy subjects lie between 5 and 6.
   • Protein (PRO)
     • The test is based on the principle of the protein error of a pH indicator. It is particularly sensitive to albumin. Quinine, quinidine, chloroquine, tolbutamide and an elevated pH (up to 9) do not affect the test.
   • Glucose (GLU)
     • The glucose determination is based on the specific glucoseoxidase/peroxidase reaction (GOD/POD method). The test is independent of the pH and specific gravity of the urine and is not affected by the presence of ketone bodies.
   • Ketone bodies (KET)
     • The peroxidase-like action of hemoglobin and myoglobin specifically catalyzes the oxidation of the indicator by means of the organic hydroperoxide contained in the test paper to give a blue-green coloration.
   • Urobilinogen (UBG
     • A stable diazonium salt reacts almost immediately with urobilinogen to give a red azo dye. The test is specific for urobilinogen and is not susceptible to the interfering factors known to affect the Ehrlich’s test
   • Bilirubin (BIL)
     • The test is based on the coupling of bilirubin with a diazonium salt. Even the slightest pink coloration constitutes a positive, i.e. pathologic, result. Other urinary constituents produce a more or less intense yellow coloration

3. Storage and stability

   • Store the package at 2-30 °C. The test strips are stable up to the expiration date specified on the box, when stored in the original container.
   • Do not use the test strip after the specified expiration date. Tightly re‑cap the container immediately after removing a test strip

4. Assay

   • For optimum performance of the assay follow the directions given in this document
     • 1. Use fresh urine that has not been centrifuged. Thoroughly mix the urine sample. The sample should be at room temperature when the test is performed and should not have been standing for more than 2 hours
     • 2. Take a test strip out of the container. Close the container again with the original desiccant stopper immediately after removal of the strip.
     • 3. Briefly (about 1 second) dip the test strip into the urine making sure that all test areas are moistened
     • 4. When withdrawing the test strip, wipe the edge against the rim of the vessel to remove excess urine
     • 5. After 60 seconds (60-120 seconds for the leukocyte test area), compare the reaction colors of the test areas with the colors on the label and assign always the value of the nearest color block
     • Any color changes appearing only along the edges of the test areas, or developing after more than 2 minutes, do not have any diagnostic significance.