Substrate Comparison
Definition
A sample used to investigate relevant background on an item, distinct from process blanks. Material from an appropriate part of an item can help investigate background contributions. Its location and relevance should be documented.
- Context
- Background examination
For example, nearby unstained material can help investigate item background while a reagent blank addresses a different part of the workflow.
A substrate comparison differs from a reagent or collection blank. One control type cannot automatically answer every contamination or background question.
Related terms
- Activity Proposition
- A stated explanation about actions or transfer, distinct from whose DNA is present. An activity question concerns actions, such as direct contact...
- Azoospermia
- The absence of spermatozoa from ejaculated semen, resulting from obstructive causes (vasectomy, ductal blockage) or non-obstructive causes (testicular failure). Azoospermic semen contains...
- Chemiluminescence
- Chemiluminescence is light emission generated by a chemical reaction rather than by an external excitation light source. Forensic applications include screening reactions...
- Collection Blank
- A control addressing relevant collection-device or handling background. Their selection should match the contamination pathways and stages being assessed. A clean control...
- Continuity Record
- Documentation connecting an exhibit’s identity, possession, handling and storage. Document material subdivisions and derivatives as part of that history. Continuity and analytical...
- Differential Extraction
- A DNA extraction method used for sexual assault evidence that separates sperm cells from epithelial cells before cell lysis, yielding two DNA...
- PSA / P30
- Prostate-specific antigen, also called p30, is a protein targeted by some assays used in forensic semen-related examination. Its interpretation depends on the...
- Whole-Item Recovery
- Collection of an item for controlled later sampling instead of immediate partial recovery. Prioritisation chooses examinations according to relevant questions, material and...
Explained in these topics
- Biological Evidence Collection ProtocolsA sample investigating background or interference from the item material.
- Semen, Saliva and Other Body Fluids as Evidence