CLINICAL LAB SCIENEC

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ESSENTIALS OF CLINICAL LABORATORY SCIENCE
In the Lab
The unknown samples should be labeled by patient name or other identifier such
as a patient number.
4. Using a Burette pipette or a 5 or 10 mL serological pipette, place the following
volumes into the labeled 13 × 100 mm tubes and mix well:
Reagent Blank (RB) Standard (S) Controls (C) Unknowns (U)
Reagent 2 mL 2 mL 2 mL 2 mL
Standard - 20 μL - -
Controls - - 20 μL -
Unknowns - - - 20 μL
5. Mix well using a vortex mixer or by covering each tube with parafilm and inverting
several times before allowing the tubes to stand for at least 5 minutes.
6. Read the absorbance of the standard and unknowns at 340 nm for SSA method
and 600 nm for the Coomassie blue dye method.
7. Record the absorbance (Abs) reading for each tube, including the standard (see
Example 12-1).
8. Calculate results by dividing the absorbance of the unknown samples by the
absorbance of the known standard. Then multiply the result obtained by the value
of the standard (See Example 12-1).
Calculation
Total Protein (mg/dL) =
Absorbance of unknown (Au) ×
Concentration
of Standard
Absorbance of standard (As)
Example 12-1
A 24-hour urine sample of 1850 mL was mixed and tested for protein.
The result of the protein was 240 mg/dL.
1850 mL / 100 mL 240 mg/dL 18.5 240 4440 mg / 24 hours
Since there are 1000 mg in 1 gram (g), 4440 / 1000 = 4.44 g / 24 hours
9. Discard all supplies used for the procedure in the appropriate containers. A
disinfectant should be used to clean the work surfaces and equipment should
be cleaned and restored to its former position. Gloves should be discarded
appropriately and the hands washed thoroughly in accordance with established
policies.
Reporting of Results
Record the results on an appropriate form. Report results for CSF and other body fluids
in mg/dL. For a 24-hour urine sample, the value is obtained for the total volume of
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