Evaluation of four digestive methods for extracting diatoms

Area of Science:

• Forensic science
• Analytical chemistry
• Microscopy

Background:

• Diatoms are microscopic algae found in water bodies.
• Their presence in tissues can indicate the cause of death, particularly drowning.
• Efficient extraction methods are crucial for accurate forensic analysis.

Purpose of the Study:

• To evaluate four digestive methods for diatom extraction from biological tissues.
• To determine the optimal method for diatom recovery in drowning investigations.

Main Methods:

• Comparison of four digestive methods: nitric acid/hydrogen peroxide, proteinase K, nitric acid in Disorganization Can, and Soluene-350.
• Assessment of digestion time, tissue digestion degree, diatom recovery ratio, and diatom structural integrity (using SEM).

Main Results:

• Proteinase K demonstrated the highest diatom recovery rates for Cyclotella, Cybella, and Navicula species.
• Nitric acid/hydrogen peroxide and nitric acid in Disorganization Can offered more thorough tissue digestion but lower diatom recovery.
• Proteinase K preserved diatom structures best, while other methods caused partial destruction.

Conclusions:

• Proteinase K is the most reliable method for diatom extraction in drowning diagnosis due to superior recovery and structural preservation.
• Nitric acid plus hydrogen peroxide serves as a suitable alternative.
• Soluene-350 is not recommended for extracting diatoms, especially from marine environments.