Novel HPLC-ICP-MS strategy for the determination of β2-Transferrin, the biomarker of cerebrospinal fluid (CSF) leakage

Abstract

Asialo-Transferrin (S₀) or β₂-Transferrin is an accepted marker of cerebrospinal fluid (CSF) leakage from the subarachnoid space into the nasal or aural cavity as the result of a head trauma. At this time, the S₀ detection method of choice is isoelectric focusing on polyacrylamide gel with direct immunofixation of transferrin (Tf) and silverstaining which are time-consuming techniques (> 5 h). The aim of this study is to present an alternative methodology for determination of Tf sialoforms present in CSF samples, specifically S₀, based on the detection of the Fe associated with those forms. A double spiking methodology is developed by saturating the protein with isotopically enriched iron (⁵⁷Fe) and conducting post-column Isotope Dilution Analysis (IDA) with ⁵⁴Fe after separation of the different sialoforms by anion exchange chromatography. The results obtained have been validated using a certified serum (ERM^®-DA470) and applied with satisfactory results to a pooled CSF sample.