20.00
Photometric
colorimetric test for determination of total protein, biuret method
Method
Cupric
ions react with protein in alkaline solution to form a purple complex. The
absorbance of this complex is proportional to the protein concentration in the
sample.
Reagent preparation and
stability
R1
(colour reagent) and 2 (standard) are ready for use. They are stable even after
opening up to the expiry date when stored at 2...25oc.
Contamination after opening must be
avoided.
Specimen
Serum.
Heparinised or EDTA plasma
Stability in serum
Up
to 1 mounth at 2...80c, up to 1 week at 15...250c.
Assay
Wavelength
: Hg 546 nm
Optical
path : 1 cm
Temperature
: 20...250c
Measurement : againts reagent balnk.
Only one reagent blank per series is required.
Pipeting scheme
|
Pipette
into cuvettes
|
Reagent
blank
|
Sample
or standard
|
|
Sample
/ standard
R1
|
--------
1000µl
|
20µl
1000µl
|
|
Mix,
incubate for 10 min. At 20...250c. Measure the absorbance of the
sample and the standard againts the reagent blank within 30 min.
|
||
Linearity
The
test is linear up to a protein concentration 12 g/dl or 120 g/l. Dilute samples
with a higher concentration 1+1 with physiological saline (0,9 %). Multiply the
result by 2.
Normal range in serum or
plasma
Normal
born babies 4,6-7,0
g/dl or 46-70g/l
Children
from 3 years and adults 6,6-8,7 g/dl
or 66-87 g/l
Quality control
For
internal quality purpose, all cemmercially available control sera with total
protein values determined by the biuret method may applied.
Automation
The
test may be performed manually or on clinical analyzers. For applications
please contact us at the address given below.
Notes:
1.
The sample blank for clear,
colorless sera is equivalent to 0,2 g/dl and can therefore be ignored. A sample
blank must be determined for haemolytic and lipemic sera by pipetting 20µl sample to 1000µl physiological saline and measuring againts
dist, water. The absorbance of the sample blank has to be subtracted from the
absorbance of the sample.
2.
The colour reagent contains sodium
hidroxide which is irritant (R 36/38). In case of contact with skin and mucous
membranes wash with copious amounts af water.
3.
The standard contains sodium azide
as preservative (0,095 %) do not swallow. Avoid contact with skin and mucous
membranes.
4.
A slight sediment may develop as
the reagent ages. Do not include this sediment in the reaction mixture
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