Standardisation
Definition
The production of a validated, peer-reviewed protocol that specifies every variable in the test: acid type and concentration, digestion time and temperature, filtration conditions, slide preparation, counting method, and reporting format. The current absence of a universally adopted standard is the most frequently cited systemic weakness of the method.
- Scope
- Every variable in a diatom test protocol
- Includes
- Acid type/concentration, digestion time, filtration, counting method
- Current status
- No universally adopted standard exists
- Cited as
- Most frequent systemic weakness of the diatom test
Common questions
Why does the lack of standardisation weaken the diatom test's evidentiary value?+
Different laboratories using different digestion, filtration, and counting protocols can produce different diatom counts from the same tissue, making it hard to compare results across cases or set universally agreed positive thresholds, which opponents can raise to challenge the test in court.
Has any body attempted to standardise the diatom test?+
Various individual laboratories and researchers have published validated protocols, but none has become a universally adopted international standard, so practice still varies between forensic institutes and jurisdictions.
Related terms
- Background Contamination
- Diatom frustules introduced into a sample from sources other than the victim's own body: tap water, laboratory air, unclean glassware, reagents, and...
- Diatom Density
- The number of frustules per unit volume of water in the drowning environment. Low-density environments (pools, tap water, diatom-poor rivers) cannot deliver...
- False Negative
- A negative result from a preparation in which ante-mortem drowning actually did occur. Causes include low diatom density in the drowning water,...
- False Positive
- A test result that indicates the presence of a target analyte when it is absent. In forensic serology this may mean incorrectly...
- Positivity Threshold
- The minimum number of frustules per gram of tissue or per slide that a laboratory uses to declare a result positive. No...