l've got rat serum samples with different background (from pink to yellow) and l'm trying to test total cholesterol, HDL and triglyceride in mice serum. l'm worried that the background noise would still exist even l diluted samples. Are there any alternatives to solve this problem? Can l spin serum again (10min, 4c, 1500rcf) before testing? Glad to hear your suggestions!
Colorimetric kits for assessing (for instance) cholesterol and triglycerides rely on measuring the conversion of a dye to a red color. Typically, these kits allow for background subtraction prior to adding the enzyme / color reagent. After correction, minor differences in plasma color should not affect the colorimetric results. Check the manual of your kit to see at which step you can take a background measurement using your plate/cuvette reader. Good luck!
There's two things I can think of, but it depends on your assay whether they're relevant.
If your colorimetric assay consists of two (or more) reagents, and the color is `developed` by the last reagent, you could measure 600nm OD immediately prior to adding the last reagent. This may be relevant if the triglyceride kit measures TGs indirectly via an assessment of glycerol. The TG kit which I used previously, and which is clinically used, performs a 'glycerol blanking' step, to be able to distinguish endogenous glycerol from the TG glycerol. In this blanking step, you are essentially also subtracting the background.
If that is not the case, and you have sufficient amount of plasma, you could prepare a buffer similar in composition to the coloring reagent, and measure the 600nm OD of the diluted plasma as is.