Automated saliva processing for LC-MS/MS: Improving laboratory efficiency in cortisol and cortisone testing

Area of Science:

• Clinical Chemistry
• Biomedical Engineering
• Analytical Chemistry

Background:

• Accurate quantification of cortisol and cortisone is crucial for diagnosing various endocrine disorders.
• Manual saliva preparation protocols can be labor-intensive and prone to variability.
• Liquid handling platforms offer potential for automating complex laboratory procedures.

Purpose of the Study:

• To implement and validate an automated saliva preparation protocol for cortisol (F) and cortisone (E) quantification using LC-MS/MS.
• To ensure the automated method maintains previously established reference intervals.
• To assess the impact of automation on hands-on time and assay performance.

Main Methods:

• An automated liquid handling platform was used for internal standard addition and solid-phase extraction (SPE) of saliva samples.
• Samples and calibrators were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS).
• Passing Bablok regression was employed to compare results from manual and automated procedures using 120 saliva samples.

Main Results:

• The automated protocol demonstrated linear calibration curves across the selected ranges.
• Assay imprecision ranged from 2-10%, with recoveries between 95-116%.
• Passing Bablok regression analysis showed no significant bias between manual and automated methods, confirming consistent reference intervals.

Conclusions:

• The liquid handling platform successfully automates manual steps in saliva preparation for cortisol and cortisone analysis.
• Automation significantly reduces hands-on time while preserving assay reproducibility and result reliability.
• The validated automated protocol is suitable for routine implementation without altering established reference intervals.