In pH4.2 buffer, albumin as a cation, combined with the anionic dye bromocresol green (BCG) to form a blue-green compound, there is an absorption peak at a wavelength of 630 nm, and its absorbance is proportional to the concentration of albumin, which can be compared with the same treatment of albumin standard to obtain the content of albumin in the serum. This experiment is from Mudanjiang Medical College, undergraduate 5-year laboratory guide for testing majors.
Operation method
Serum albumin bromocresol green assay assay experiment
Principle
In pH 4.2 buffer, albumin as a cation, combined with the anionic dye bromocresol green (BCG) to form a blue-green compound, there is an absorption peak at a wavelength of 630 nm, and its absorbance is proportional to the concentration of albumin, and compared with the same treatment of the albumin standard can be obtained from the content of albumin in the serum. Move I. Experimental reagents. Caveat 1, experiments have proved that BCG not only with albumin color, but also with a variety of protein components color which to globulin, transferrin, fusion bead protein is more significant, the degree of reaction is slightly slower than the protein, so some people advocate the use of a fixed value of reference serum as a standard is more desirable, after the specific binding of BCG and serum, read the absorbance in this 30 seconds, can significantly reduce the non-specific binding reaction. 2， when 60g / L albumin standard and BCG binding, solution aperture 1.0cm., measured at 630nm absorbance 0.811sh 0.035,. If this value is not reached, it means that the sensitivity is poor. 3， the method of determination of normal serum specimens of the batch coefficient of variation -6.3% or so. 4， the reagent of polyvinyl lauryl ether chloride can also be used in place of other surface activators, such as Tween-20, etc., the dosage of 2ml / L. For more product details, please visit Aladdin Scientific website.
1, 0.5 mol / L succinic acid buffer storage solution (PH4.0) dissolve Na0H 10g succinic acid 56g in 800m1 distilled water, with 1 mol / L sodium hydroxide adjusted to pH4.1 + 0.05 diluted with water to 1000ml of this solution at 4 ℃ refrigerator storage.
2, BCG has been stored solution (10mol / L): Dissolve BCG (MW = 720.22) 1.80g in 5m1 Na0H in distilled water diluted to 250ml.
3、Sodium azide storage solution: dissolve 40g of sodium azide in 1000ml of distilled water.
4, polyethylene oxide lauryl ether (BYij-35) storage solution: dissolve 2.5g of polyethylene oxide lauryl ether in 80ml of distilled water, heat to dissolve and then add distilled water to 10ml.
5, BCG reagent: with a 1L volumetric flask of distilled water about 400m1, add 100ml of succinic acid buffer storage, accurately add the BCG storage solution with a pipette 8.0m1, and use distilled water to rinse a small amount of dye residue on the wall of the pipette to the liquid add sodium azide 25ml, 25ml of ethylene vinylidene oxide lauryl ether and finally diluted to the scale with distilled water, with a BCG reagent should be 4.15 earth 0.05.
6、40g/L albumin standard application liquid
Second, the experimental operation: according to the following table
Wavelength 630nm, with a blank tube zero, with a quantitative liquidizer plus BCG application solution and serum specimens mixed, immediately in 30 soil 3S, read absorbance, if the specimen is turbid specimen blank tube (serum 0.02m1 plus 40ml of succinic acid buffer) with succinic acid buffer to determine the zero specimen buffer tube absorbance, absorbance tube absorbance subtracted from the specimen blank tube absorbance to calculate the results.
Experimental operation: according to the following table 
Calculation:
Serum albumin from (g / L) = assay tube absorbance / standard tube absorbance × standard tube albumin concentration (g / L)
Meanwhile, the total protein concentration of the serum specimen is measured, and the serum albumin concentration is subtracted to obtain the serum globulin concentration, and the serum albumin and globulin ratio can be calculated.
Reference value: 35-55g/L