Topic: Practical Training
Podium Presentation in Room 6 on Thursday at 11:00 (Chair: Zlata Clark / Jacqueline Hubbard)
Authors: Zlata D. Clark
The popularity of LC-MS/MS-based methods for clinical testing continues to rise. However, despite their superior analytical specificity, these methods may still suffer from interference affecting method accuracy and precision, and hence negatively impacting patient care.
The aim of this Practical Training Track session is to introduce the participant to the following:
•Sources of guidelines for interference testing in method development/validation and routine testing (CLSI, CAP, SWGTOX)
•What is analytical interference and where does it come from?
•How do we define acceptable interference levels?
-When defining acceptable interference levels, consider the clinical context in which a test result will be used as well as the allowable analytical error limits.
•How do we test for interference in LC-MS/MS?
-Testing for specific interference (known drug, medication, supplement, sample abnormality, etc., added to the sample) vs. testing for unidentified interference (interference that cannot be anticipated or identified beforehand).
•When do we test for interference?
-Preferably, interference testing should be an integral part the method development process. Waiting until method validation to perform these experiments may result in unwanted surprises. Labs should use as many patient specimens as practical to ensure capturing the biological variability of interference.
•The use of internal standard in mitigating interference
•How do we monitor for interference?
-Even the best method development strategies rarely are able to prevent interference completely. Hence, the need to monitor for interference in routine testing to avoid reporting compromised results is undisputable. The most relevant data quality metrics are ion ratios, absolute internal standard areas, and retention times. Deviations in these metrics can signal the presence of interference in either the analyte or internal standard mass chromatograms.
Examples of interference issues in various methods and how they were resolved will be shown throughout the entire session.
After each respective segment, attendees should be able to:
1.List sources of guidelines for interference testing
2.Define analytical interference and identify its various sources
1.Describe the different types of experiments used for interference testing in LC-MS/MS
2.Explain why waiting until validation to test for interference is not be desirable
1.Discuss the role of internal standard in mitigating interference
2.Name parameters used for interference monitoring
Many thanks as well to Donald Mason, Lisa Calton, and Stephen Balloch for their contributions as coauthors of the Clinical Laboratory News article “Interference Testing and Mitigation in LC-MS/MS Assays,” used in preparing this presentation. This work was supported in part by ARUP Institute for Clinical and Experimental Pathology®.
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