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Colorimetric PBG Assay (Ehrlich)
COLORIMETRIC PORPHOBILINOGEN ASSAY (EHRLICH)
Modified Ehrlich Reagent
- Dissolve 1.0 gm p-dimethyl aminobenzaldehyde in 30mL glacial acetic acid.
- Add 8.0 mL 70% perchloric acid.
- Bring to 50 mL with glacial acetic acid.
- Store in the dark at 4˚C for about 2 weeks.
Porphobilinogen (PBG) Assay
- Mix 2.0mL sample with 2.0mL fresh modified Ehrlich reagent.
- Measure absorbance at 555nm.
Standard PBG
- Prepare 0.54mg/mL (2.2mM) PBG stock in 0.1M Tris pH 7.65.
- (Store at -20˚C until needed.)
- Dilute 1:1000 in H2O.
- Mix 2mL with 2mL fresh modified Erlich reagent.
- Measure absorbance at 555nm.
- 1mM PBG = 61 abs units at A555.
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