Direct Spectrophotometric Method for Measurement of Bilirubin in Newborns: Comparison with HPLC and an Automated Diazo Method, Steven C. Kazmierczak,1 * Alex

The measurement of serum total bilirubin is one of the most frequently performed tests in newborns (1–3). Direct spectrophotometry for the measurement of bilirubin in sera from newborns is a simple and rapid method that requires minimal sample for analysis (4). The direct spectrophotometric assay is based on the absorbance of bilirubin at 454 nm; by contrast, hemoglobin absorbs equally at both 454 and 528 nm. Subtraction of the absorbance at 528 nm from that at 454 nm eliminates the effect of hemolysis and yields a value that can be attrib-uted primarily to bilirubin. Unfortunately, other pig-ments, such as carotenoids, also absorb at 454 nm, thus limiting this technique to neonates 2–3 weeks of age. Direct spectrophotometric methods have been com-pared with diazo (Jendrassik–Gróf-based) bilirubin meth