Your company sells two different kit (DIAG-250 and DIAP-250). What are the differences between them exactly? Is it just the wavelength of detection?
The two kits use different albumin specific dyes and hence the major difference lies in the sensitivity and wavelengths. Both assays have advantages and disadvantages. DIAG-250 (QuantiChrom BCG Albumin Assay Kit) uses bromcresol green, a dye that is more (about 2-fold) sensitive than bromcresol purple used in the BCP albumin assay. BCG is not absolutely specific for albumin, however, it also reacts with α1- and α2-globulins, and adds a positive bias. The BCP method, although more specific, underestimates albumin in certain samples, e.g. from patients undergoing hemodialysis. If your samples are sera or plasma, which have high albumin concentrations, I would suggest using the DIAP-250 assay kit (detection wavelength 610 nm). If the albumin concentration is low, DIAG-250 is the best choice (detection wavelength 620 nm).Pooled plasma samples (EDTA) show high albumin concentrations with the bromcresol purple assay? What could be interfering with the assay?
There should be no significant differences between serum samples and plasma samples. Turbid plasma samples (fibrinogen) can cause high albumin readings. This can be adjusted for by blanking samples at OD 690 nm. BCP does not absorb at 690 nm, whereas the absorbance caused by turbididty is the same at 610 nm and 690 nm.Since the concentration that I am measuring is very low, would it be reasonable to dilute the standard curve down to lower level so my sample is still within the curve?
Yes, as long as the standard curve is within the limits of the dynamic range, but this will not increase the sensitivity of the assay. To increase the sensitivity add a larger volume of sample and standard. For example, you could add 20 μL sample and 20 μL of diluted standards (instead of starting at 5 g/dL as shown in the standard protocol, start at 1 g/dL).For more detailed product information and questions, please feel free to Contact Us. Or for more general information regarding our assays, please refer to our General Questions.