Direct identification of forensic body fluids by MALDI-MS

Area of Science:

• Forensic Science
• Analytical Chemistry
• Biochemistry

Background:

• Accurate identification of human body fluids is critical for forensic investigations.
• Existing methods for body fluid identification often lack sensitivity, are time-consuming, and require large sample volumes.

Purpose of the Study:

• To develop a rapid, sensitive, and low-sample-volume mass spectrometry method for distinguishing human body fluids.
• To identify unique small molecular biomarkers for differentiating various body fluids.

Main Methods:

• Utilized mass spectrometry with a novel matrix, N-(1-naphthyl)ethylenediamine dihydrochloride (NEDC), for high sensitivity and salt tolerance.
• Analyzed small molecular regions, including heme, creatinine, and uric acid, as potential biomarkers.
• Applied principal component analysis (PCA) for sample clustering and classification.

Main Results:

• Successfully differentiated five human body fluids (blood, semen, urine, sweat, saliva) using characteristic metabolites.
• Achieved 75% clustering of body fluid types with three principal components via PCA.
• Demonstrated high accuracy in blind testing, correctly classifying 90% of unknown samples.
• Showed minimal interference from storage time (up to 12 months) and common carrier materials.

Conclusions:

• The developed mass spectrometry method offers a rapid (under 10 minutes), efficient, and highly sensitive approach for human body fluid identification.
• This technique has significant implications for improving screening processes in forensic casework.
• The method's ability to use minimal sample volumes and tolerate complex matrices enhances its practical applicability.