The study of interferences for diagnosing albuminuria by matrix-assisted laser desorption ionization/time-of-flight mass spectrometry

BackgroundMatrix-assisted laser desorption ionization/time-of-flight (MALDI-TOF) mass spectrometric analysis of albumin (ALB) biomarkers is an alternative approach toward the rapid diagnosis of proteinuria for screening a large number of samples. The aim of this study is to reveal if interfering factors in urinary dipstick approach would affect the results of diagnosing albuminuria by MALDI-TOF MS.MethodsThe effects of various interfering chemicals on the diagnosis of albumin in urine were examined using both MALDI-TOF mass spectrometric and dipstick approaches. Semi-quantification of albumin was performed by using MALDI-TOF MS.ResultsInterferences from various drugs, detergents, vitamins and their metabolites, alkaline, and blood, which often cause false-positive and false-negative results in conventional urinary dipstick analysis, are avoided when using this MALDI-TOF MS approach. It was found that the intensity of + 1 and + 2 albumin ions varies with the albumin concentration. A log/log plot of the intensity ratio vs. albumin concentration is then used as a calibration curve for semi-quantifying the albumin in urines.ConclusionsMALDI-TOF MS is an effective approach toward avoiding interferences caused by various chemical compounds during the rapid diagnosis of albumin in urine. Semi-quantification of albuminuria is also achieved by this MALDI-TOF MS approach.

► MALDI-TOF MS can be used to sensitively characterize albumin in urine samples.
► We examined the effects of interfering chemicals on the albuminuria diagnosis.
► The matrix factors did not affect the detection of albumin through MALDI-TOF MS.
► MALDI-TOF MS is a rapid and unambiguous approach for screening albuminuria.