The BioDeviceLab Cortisol ELISA Kit is a high-sensitivity, competitive enzyme-linked immunosorbent assay designed for the quantitative measurement of cortisol in biological samples. The assay combines robust performance, excellent selectivity, and a wide dynamic detection range, making it suitable for both conventional laboratory use and advanced biodevice development workflows.

For Research Use Only (RUO).

Intended Use

This kit is intended for the quantitative determination of cortisol in:

Serum
Plasma
Saliva
Cell culture supernatants

Applications include stress and endocrine research, biomarker validation, wearable and point-of-care assay development, organ-on-chip studies, and biodevice calibration.

Assay Principle

This assay employs a competitive ELISA format:

Cortisol in the sample competes with enzyme-labeled cortisol for binding to anti-cortisol antibodies immobilized on a 96-well microplate.
Following washing, a chromogenic substrate (TMB) is added.
The enzymatic reaction produces a color signal measured at 450 nm.
Absorbance is inversely proportional to cortisol concentration.

Calibration Curve

A calibration curve is generated using a series of cortisol standards with known concentrations.
Mean absorbance values are plotted against cortisol concentration on a semi-logarithmic scale.
A four-parameter logistic (4PL) regression model is recommended for curve fitting.
Due to the competitive assay format:
- Higher cortisol concentrations result in lower absorbance values.
Sample concentrations are calculated by interpolation from the standard curve.
A fresh calibration curve should be generated for each assay run.

Analytical Performance

Dynamic Detection Range

0.1 – 30 ng/mL

This range supports accurate quantification across physiologically relevant cortisol concentrations in multiple biological matrices.

Analytical Sensitivity

Limit of Detection (LOD): ≤ 0.05 ng/mL

The assay enables reliable detection of low cortisol concentrations relevant to baseline and circadian hormone levels.

Precision

Intra-assay CV: < 10%
Inter-assay CV: < 12%

Selectivity & Specificity

The assay demonstrates high selectivity for cortisol with minimal cross-reactivity to structurally related steroids.

Typical cross-reactivity values (representative):

Cortisol: 100%
Cortisone: < 10%
Prednisolone: < 1%
Progesterone, Testosterone, Estradiol: < 0.1%

This selectivity ensures accurate cortisol quantification in complex biological samples.

Kit Components

Each kit contains sufficient reagents for up to 96 determinations:

Antibody-coated 96-well microplate
Cortisol standards (lyophilized, multiple concentrations)
Enzyme-labeled cortisol conjugate
Assay buffer
Wash buffer (10×)
TMB substrate
Stop solution
Detailed protocol

Required Materials (Not Provided)

Microplate reader (450 nm)
Micropipettes and tips
Plate washer or manual washing setup
Plate shaker (recommended)
Deionized or distilled water

Sample Collection & Handling

Collect samples using standard laboratory procedures.
Avoid repeated freeze–thaw cycles.
Samples exceeding the highest standard should be diluted using assay buffer.
Hemolyzed, lipemic, or contaminated samples may affect assay accuracy.

Quality Control

Standards and controls should be included in each assay run.
Duplicate measurements are recommended.
Acceptance criteria should be established by the user according to the intended application.

BioDeviceLab applies quality-controlled reagent preparation and batch-to-batch consistency practices, supporting reproducibility and scalability for biodevice development.

Storage & Stability