Forensic Characteristics for Three Types of Glass Particles, Their Formation Mechanism, and Vial Container Vulnerable Areas
| Tools | Glass Chip | Glass Lamellae | Silica Gel |
|---|---|---|---|
| OM | • Thick, transparent, shiny with irregular shape by OM | • Flat, shiny, barely visible | • Powder like, discrete |
| SEM | • Clear 3 dimensional structure by SEM | • Very thin layer, lack of third dimension feature | • Gel-like, uneven surface |
| MFI | N/A | • Transparent, anisotropic, and with sharp edges | • Amorphous |
| EDS | • Detect Si, O, Na, Al | • Detect Si, O | • Detect Si, O |
| FTIR | • Si-O stretch at 1079 cm−1 • Silanol peak at 953 cm−1 | • Si-O stretch at 1096 cm−1 sometimes lower | • Si-O stretch at 1059 cm−1 • Silanol peak at 953 cm−1 |
| Particle Formation Mechanism | • Physically breaking off as a big chunk from capping/decapping or shipping | • Dislodgement of very topical surface from chemical or mechanical stresses | • Dissolution of silica in liquid form and re-polymerization upon freeze-thawing |
| Vulnerable Area of Vial | • Shoulder, mouth | • Under the filling line, more likely to be close or on the bottom | • Under the filling line |