The presence of oxyhaemoglobin and biliverdin interferes with the method recommended by the UK NEQAS Specialist Advisory group for EQA of CSF Proteins and Biochemistry for estimating of the net bilirubin absorbance in CSF. This is easily demonstrated by using solutions with different concentrations of these three substances.The two secondary peaks of the oxyhaemoglobin spectrum at 540 nm and 577 nm are used as reference to minimize these interferences. Those peaks have the same absorbance as at 456 nm in the oxyhaemoglobin spectrum, independent of its concentration. This wavelength is very close to the maximum absorption of bilirubin and, therefore, is suitable for estimating the net bilirubin absorbance.A preliminary study with 48 spectrophotometric analyses of CSF from patients who were suspected of having subarachnoid haemorrhage were used to compare both net bilirubin absorbance estimation methods.The new method is practically free of oxyhaemoglobin and biliverdin interference. This allows for higher sensitivity and a more realistic estimation of the bilirubin concentration in a sample.A better estimation of the bilirubin concentration can have special relevance for diminishing the amount of equivocal or inconclusive cases and also to improve the prematurity of the diagnosis.

中文翻译：

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测定脑脊液中净胆红素吸收的新方法，可最大程度地减少氧合血红蛋白和胆绿素的干扰。

氧合血红蛋白和胆绿素的存在干扰了英国NEQAS专家咨询小组推荐的CSF蛋白质和生物化学EQA估计净CSF中胆红素吸收的方法。通过使用具有不同浓度的这三种物质的溶液可以很容易地证明这一点。氧合血红蛋白光谱的两个次级峰分别在540 nm和577 nm处用作最小化这些干扰的参考。这些峰在氧合血红蛋白光谱中具有与456 nm相同的吸收度，而与浓度无关。该波长非常接近胆红素的最大吸收，因此适合估算净胆红素的吸收率。通过对48例蛛网膜下腔出血疑似患者的脑脊液进行分光光度分析的初步研究，比较了两种净胆红素吸收率估算方法，该新方法几乎不受氧合血红蛋白和胆绿素的干扰。这样可以提高灵敏度并更真实地估计样品中的胆红素浓度。更好地估计胆红素浓度可以与减少不确定性或不确定性病例的数量特别相关，并可以提高诊断的早熟程度。