Direct seminal fluid identification by protease-free high-resolution mass spectrometry

Area of Science:

• Forensic Science
• Biochemistry
• Analytical Chemistry

Background:

• Traditional serological screening for seminal fluid is presumptive and lacks sensitivity compared to DNA testing.
• Current mass spectrometry methods for seminal fluid detection are specific and sensitive but require time-consuming sample preparation.

Purpose of the Study:

• To develop and validate a streamlined peptidomics approach for rapid and sensitive seminal fluid identification.
• To overcome the limitations of traditional serological methods and lengthy mass spectrometry protocols in forensic analysis.

Main Methods:

• A novel one-step peptidomics strategy was employed, eliminating the need for trypsin digestion.
• High-resolution mass spectrometry was utilized to identify endogenous seminal fluid peptides and low-molecular weight proteins.
• Simulated casework samples (e.g., stained oral and vaginal swabs) were analyzed to assess forensic applicability.

Main Results:

• Multiple seminal fluid protein biomarkers, including Semenogelin I and II, Prostate Specific Antigen/p30, and Prostatic Acid Phosphatase, were confidently identified.
• The streamlined approach successfully detected sub-microliter quantities of seminal fluid on cotton swabs.
• High sequence coverage was achieved for key biomarkers, demonstrating the method's robustness.

Conclusions:

• The developed peptidomics assay provides a sensitive, specific, and rapid method for seminal fluid identification in forensic samples.
• This streamlined approach enables same-day sample preparation and analysis, significantly improving efficiency in sexual assault investigations.
• The method shows strong forensic applicability and potential for future development in analyzing other biological stains.