Simple and sensitive method for the quantification of total bilirubin in human serum using 3-methyl-2-benzothiazolinone hydrazone hydrochloride as a chromogenic probe.

We here describe a new spectrophotometric method for measuring total bilirubin in serum. The method is based on the cleavage of bilirubin giving formaldehyde which further reacts with diazotized 3-methyl-2-benzothiazolinone hydrazone hydrochloride giving blue colored solution with maximum absorbance at 630 nm. Sensitivity of the developed method was compared with Jendrassik-Grof assay procedure and its applicability has been tested with human serum samples. Good correlation was attained between both methods giving slope of 0.994, intercept 0.015, and R(2)=0.997. Beers law obeyed in the range of 0.068-17.2 μM with good linearity, absorbance y=0.044 C(bil)+0.003. Relative standard deviation was 0.006872, within day precision ranged 0.3-1.2% and day-to-day precision ranged 1-6%. Recovery of the method varied from 97 to 102%. The proposed method has higher sensitivity with less interference. The obtained product was extracted and was spectrally characterized for structural confirmation with FT-IR, ¹H NMR.