Plasma fibrinogen assay

Summary

Through this experiment, trainees can master the principle and method of plasma fibrinogen determination and the preparation of reagents. This experiment is from the laboratory guide of Mudanjiang Medical College undergraduate 5-year testing program.

Operation method

Plasma fibrinogen assay

Principle

Add appropriate amount of sodium sulfite to plasma; make fibrinogen form a precipitate, the rest of the protein are still in solution. The precipitate is dissolved in sodium chloride solution and the amount of protein is determined by urea.

Move

I. Experimental reagents:

1.12.5% sodium sulfite solution: weigh anhydrous sodium sulfite (A. R or GP) 125g dissolved in distilled water and diluted with distilled water to 1000m1.

2. 9g / L NaCL solution

3. double urea reagent

4. standard albumin serum

II. Method of operation:

In 15 × 100mm test tube add plasma 0.5ml, then add water 125g / L sodium sulfite solution mixing, placed in 37 ℃ water soluble for 15min or longer, remove, centrifugation, discard the supernatant, precipitate and then 125g / L sodium sulfite solution to wash for more than three hours. When washing with a small amount of sodium sulfite to make it disperse evenly. Centrifugation should be discarded supernatant, the test tube on filter paper, drench the tube liquid in the tube to add 9g / L NaCL 1.0ml, fully mixing stage so that the precipitate is dissolved that is the "test tube", in another test tube with a 0.lm1 graduated pipette to accurately add the standard serum 0.05m1 and add 9g / L NaCL soluble wave 0.95m1, mixed as a standard test tube, and add 0.95m1 to add the standard test tube. Add 0.05m1 of standard serum and 0.95m1 of 9g/L NaCL solution into another test tube and mix it as a standard test tube, and add 1ml of 9g/L NaCl solution into another test tube as a blank tube.

In the blank tube standard and determination of the tube each with a bioconjugate reagent, mixed at room temperature for 30min540nm wavelength for colorimetry to the blank tube to correct the absorbance to the zero point, read the absorbance readings in each tube.

Third, calculation:

Measurement tube absorbance / standard tube absorbance × O.1 × standard serum protein concentration = fibrinogen g / L plasma

Caveat

1. The action of sodium sulfite and plasma, sometimes 10min can not make fibrin precipitation, can be adapted to prolong the time.

2. the precipitate is washed with sodium sulfite first in order to support the proteins other than fibrin, so the precipitate must be evenly dispersed in the washing.

3. If the fibrinogen is completely or partially dissolved by the sodium sulfite solution during the washing of the precipitate, the tube can be placed in a water bath at 37°C to wait for the fibrinogen to be precipitated.When selecting the standard solution, it is not possible to select any protein with unknown properties as the standard solution for serum proteins.

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