Mobile Medical Applications - Holographic Sensors - page 138

Table 6.2 The principles of colorimetric reactions in Cobas ® Combur 3 Test ® , Roche
Assay Reactive ingredient (per 1 cm 2

patch area)

Test principle Range Detection

limit

Operating
temp. ( ° C)

Ingredients speci cally react with H + ; the pH is the
negative common logarithm of the H 3 O + concentra-
tion. The tests pad change colour from orange to
greenish blue as the pH increase

pH Bromothymol blue (13.9 μ g),

methyl red (1.2 μ g) and phenol-
phthalein (8.6 μ g)

5.0 - 9.0 0.5 stable up

to boiling
point

Protein Based on protein error principle of a pH indicator.

The test pad changes colour from yellow to greenish
blue in the presence of albumin

3 -Tetrachlorphenol-

3,4,5,6-tetrabrom-sulfophthalein
(neutral form) (13.9 μ g)

′ ,3 ″ ,5 ′ ,5 ″ 0 - 100 mg/dL 6 mg

albumin/dL

stable up
to boiling
point

Glucose Based on glucose oxidase/peroxidase reaction.

The reaction pad changes colour from yellow
to dark blue in the presence of glucose

Tetramethylbenzidine (103.5 g), 0 300 mg/dL 40 mg/dL <55

μ -

glucose oxidase
(6 U) and peroxidase (35 U)