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Endogenous lysozyme inactivation in EMIT-dau assays
Journal of Analytical Toxicology
|November 1, 1982
Summary
Extraction is the best method to remove interfering endogenous lysozyme activity in urine. Other methods like heating or filtration are ineffective or alter drug assay results, making them unsuitable for EMIT immunoassays.
Area of Science:
- Clinical Chemistry
- Immunoassay Technology
Background:
- Endogenous lysozyme activity in urine can interfere with immunoassay results.
- Accurate drug of abuse testing requires minimizing such interfering substances.
Purpose of the Study:
- To evaluate alternative methods for removing endogenous lysozyme activity from urine samples.
- To determine the suitability of these methods for EMIT (Enzyme Multiplied Immunoassay Technique) immunoassays.
Main Methods:
- Investigated micropore filtering, heat treatment (65°C and 85°C), and methanol precipitation.
- Assessed the effectiveness of these methods in removing lysozyme activity.
- Evaluated the impact of heat treatment on drug assay responsiveness.
Main Results:
- Micropore filtering, 65°C heat treatment, and methanol precipitation were ineffective.
- Heating urine to 85°C for 30 minutes removed lysozyme activity.
- However, 85°C heat treatment unpredictably altered the responsiveness of drug of abuse urine assays.
Conclusions:
- Extraction remains the preferred method for removing endogenous lysozyme activity.
- 85°C heat treatment is not recommended for all EMIT immunoassays due to assay interference.