The simultaneous determination of cortisol and dexamethasone provides additional analytical context within the same serum or plasma sample. In addition to cortisol, the method provides information on the presence and concentration of dexamethasone. Cortisone is included in the same method as an additional endogenous glucocorticoid parameter.

This combination supports a more complete research dataset for applications in which endogenous glucocorticoids and dexamethasone exposure are evaluated within the same research protocol.

The method uses UHPLC-MS/MS with MRM detection. The combination of chromatographic separation, mass selective detection and deuterated internal standards supports selective quantification within one analytical workflow.

The Cortisol & Dexamethasone LC-MS/MS kit is suitable for human serum, EDTA plasma and lithium heparin plasma. This allows laboratories to use the kit with different sample matrices commonly applied in laboratory research.

The kit is available in two configurations, depending on the preferred sample preparation workflow, the Evaporation Method and the SPE Method.

The 1320E KIT M CCD has been developed for the Evaporation Method. This workflow consists of protein precipitation, centrifugation, evaporation under nitrogen and reconstitution before LC-MS/MS analysis.

This configuration is intended for laboratories looking to implement a practical and cost effective sample preparation workflow. The Evaporation Method does not require an SPE step and limits the need for additional consumables. Depending on the available laboratory infrastructure, the liquid handling steps may be semi automated.

The 1320S KIT M CCD has been developed for the SPE Method. This workflow uses solid phase extraction for enhanced sample clean up before LC-MS/MS analysis.

The SPE Method may be relevant for laboratories aiming for additional matrix removal, contamination control or analytical sensitivity. Depending on the available infrastructure, this workflow can be combined with automated SPE platforms or SPE compatible liquid handling systems.

The analytical performance of the Evaporation Method has been established by technical validation. The SPE Method has also been evaluated by method comparison against the Evaporation Method.

In the technical validation, limits of quantification were established at 0.785 nmol/L for cortisol, 0.916 nmol/L for cortisone and 0.500 nmol/L for dexamethasone. Repeatability CVs ranged from 0.6 to 6.2 percent, depending on the analyte and concentration level. For the comparison between the Evaporation Method and the SPE Method, correlation coefficients were 0.9988 for cortisol, 0.9983 for cortisone and 0.9855 for dexamethasone.

Accuracy and trueness were assessed against predefined target ranges. For cortisol, accuracy was evaluated using external materials over a target midpoint range of 232 to 800 nmol/L. Trueness was assessed for cortisol, cortisone and dexamethasone using calibrator and control materials across relevant concentration ranges. The experiments met the predefined acceptance criteria.