Chemistry Reference
In-Depth Information
Table 1.3
The principles of colorimetric reactions in commercial urinalysis tests
Assay
Reaction
Range
Detection limit [
144
]
Glucose
5.5
55
2.2 mmol/L
glucose oxidase
Gluconolactone + H
2
O
2
Chromogen + H
2
O
2
!
-
Glucose + O
2
!
peroxidase
H
2
O + dye
Protein
30
300
6 mg/dL albumin
protein
-
Tetrabromophenol blue (pH 3, yellow)
!
tetrabromophenol blue (>pH 4.6, blue)
Blood
10
80
5
10 erythrocytes/L
haemoglobin
peroxide
-
-
H
2
O
2
+ chromogen
oxidised chromogen + H
2
O
2
!
Leukocytes
15
-
125
10
-
25 leukocytes/
μ
L
granulocytic
exterase
Indoxyl or pyrole carbonic acid ester
!
Indoxyl or pyrole
Indoxyl or pyrole + diazonium salt
→
dye (purple)
Nitrite
Nitrite + p-arsanilic acid
→
diazonium compound
3-Hydroxyl-1,2,3,4 tetrahydrobenz-(h)-quinoline + diazonium compound
→
pink colour
Qualitative
11
μ
mol/L
HInd (acid form) + H
2
O
H
3
O
+
+ Ind
−
(conjugate base of the indicator)
pH
4
-
9
0.25 pH units
Ketone
alkaline
0.5
4.0
5 mg/dL
-
Acetoacetic acid + Na nitroprusside + glycine
violet to purple colour
!
Urobilinogen
p-diethylaminobenzaldehyde + urobilinogen
→
azo compound (red)
17
-
200
μ
mol/L
7 mol/L
Bilirubin
acid
+-+++
9
μ
mol/L
Bilirubin + diazide
!
azobilirubin
