hCGβcf as a quality control marker for urine mass spectrometry analysis

Human chorionic gonadotropin β-core fragment (hCGβcf) is a polypeptide considered to be ubiquitously present in urine regardless of race, sex, and age. This fragment is mainly produced by the degradation of human chorionic gonadotropin in the kidney and excreted in the urine, representing around 80% of total hCG in urine. The presence of hCGβcf in urine has been extensively used for noninvasive clinical diagnostics assays associated with pregnancy. Matrix-Assisted Laser Desorption Ionization Time of Flight (ToF) mass spectrometry (MS) is a rapid, affordable, and powerful diagnostic technique that is starting to find an increasing presence in clinical laboratories. hCGβcf has been used as biomarker of pregnancy and cancer, and, in this chapter, we discuss its potential as quality control marker for urine analysis using MALDI-ToF mass spectrometry. We focus on hCGβcf spectral properties and discuss the advantages and disadvantages to its use as quality control calibrator for MS analysis of urine. Further, we will present how can hCGβcf be implemented as quality control measure in a routine laboratory analysis and in high-throughput analysis of mass spectral data.