Direct identification of forensic body fluids using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The examination of body fluids such as blood, seminal fluid, urine or saliva is a key aspect of forensic science in regards to investigation of crimes against the person such as murder and rape. This article describes a streamlined and simplified approach for the identification of body fluids using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF-MS) that avoids fractionation or isolation of proteins. It is applicable to the examination of microliter quantities (or less) of neat fluids, extracts or suspensions of dried fluids or deposits of fluids in situ on tufts of fibers plucked from fabrics, which has practical application in the examination of crime-related items such as underwear or face masks. Hemoglobin was used as a marker for blood, α-amylase for saliva, semenogelins, prostate-specific antigen and acid phosphatase for seminal fluid and uromodulin for urine. Aged stains were successfully analyzed; blood proteins were easily detected in an 11-year-old blood stain.