| Field | Specification |
|---|---|
| Mfr No | |
| Alternative Names | (11β)-11,17,21-trihydroxypregn-4-ene-3,20-dione |
| Assay Type | |
| Detection Method | |
| Product Type | |
| Sample Type(s) | Dried Fecal Samples, Saliva, Urine, Serum, EDTA Plasma, Heparin Plasma, Tissue Culture Media |
| Sensitivity | |
| Shipping | |
| Species | |
| Storage | |
| Target |
Scientific Background
Cortisol (C₂₁H₃₀O₅), the primary glucocorticoid hormone produced by the zona fasciculata of the adrenal cortex, is synthesized in an ACTH-dependent manner following activation of the hypothalamic–pituitary–adrenal (HPA) axis. Its secretion follows a robust diurnal rhythm, peaking in the early morning (06:00–08:00) and declining to nadir in late evening—a pattern disrupted in depression, Cushing's syndrome, and post-traumatic stress disorder.
Only free cortisol (~4% of total circulating cortisol) is biologically active and able to traverse the blood–brain barrier to bind glucocorticoid receptors (GR) widely expressed in the hippocampus, prefrontal cortex, and amygdala. Chronic HPA axis dysregulation suppresses hippocampal neurogenesis, reduces BDNF expression, and promotes dendritic atrophy in pyramidal neurons—mechanisms implicated in stress-induced depression, MCI, and accelerated neurodegeneration in Alzheimer's disease.
Cortisol measurement in multiple biological matrices (serum, saliva, urine, fecal extracts) allows non-invasive longitudinal profiling of HPA axis reactivity, making it an indispensable biomarker in stress biology, psychoneuroimmunology, and clinical neuroscience research.
Product Description
StressXpress®
The Cortisol EIA Kit (Cat. # SKT-201) from StressMarq Biosciences is a research-grade kit for quantitative Cortisol measurement in Dried Fecal Samples, Saliva, Urine, Serum, EDTA Plasma, Heparin Plasma, Tissue Culture Media. This kit employs a competitive immunoassay principle with colorimetric TMB/spectrophotometric readout on a standard 96-well microplate reader.
Product Specifications
| Analyte / Target | Cortisol |
|---|---|
| Assay Type | Competitive EIA (Enzyme Immunoassay) |
| Detection Method | Colorimetric (microplate spectrophotometry) |
| Sensitivity | 17.3 pg/ml |
| Detection Range | 100–3,200 pg/ml |
| Compatible Matrices | Dried Fecal Samples, Saliva, Urine, Serum, EDTA Plasma, Heparin Plasma, Tissue Culture Media |
| Species Reactivity | Species Independent |
| Throughput | 40 samples in duplicate |
| Incubation Time | 90 Minutes |
| Platform | Microplate (96-well) |
| Catalog Number | SKT-201 |
| Storage | 4ºC |
| Trademark | StressXpress® |
Assay Principle
This kit uses a competitive or sandwich enzyme immunoassay (EIA) format—a microplate-based immunoassay technique functionally equivalent to ELISA. Cortisol in the sample competes with enzyme-labeled conjugate for a limited number of antibody binding sites. Bound conjugate is detected colorimetrically via TMB substrate; absorbance is inversely proportional to the Cortisol concentration, interpolated from a calibration curve (range: 100–3,200 pg/ml).
The kit measures total Cortisol and is fully validated for use in Dried Fecal Samples, Saliva, Urine, Serum, EDTA Plasma, Heparin Plasma, Tissue Culture Media. The Steroid Solid Extraction Protocol (where provided) enables reliable extraction from complex matrices such as dried fecal samples.
Kit Components
| Component # | Description | Quantity / Volume |
|---|---|---|
| SKC-201A | Clear Microtitre 96-well Plate | 1 Plate |
| SKC-201B | Cortisol Standard | 125 µl |
| SKC-201C | StressXpress® Cortisol Antibody | 3 ml |
| SKC-201D | StressXpress® Cortisol Conjugate | 3 ml |
| SKC-201E | Assay Buffer | 28 ml |
| SKC-201F | Dissociation Reagent | 1 ml |
| SKC-201G | Wash Buffer Concentrate | 30 ml |
| SKC-201H | TMB Substrate | 11 ml |
| SKC-201I | Stop Solution | 5 ml |
| SKC-201J | Plate Sealer | 1 each |
Quality Control & Validation
✓ Peer-Reviewed & Research Validated
Each lot is validated for sensitivity, intra-assay precision (CV <10%), and linearity of recovery. Products from the StressXpress® range cite published peer-reviewed literature for independent validation.
Safety & Regulatory
ADR Classification: Non-hazardous. Shipping: cold-chain (blue ice). Harmonized Tariff Code: 3822.19.0030 (UNSPSC: 12352203). Country of Origin: Canada.
The kit is validated for use with the following sample matrices: Dried Fecal Samples, Saliva, Urine, Serum, EDTA Plasma, Heparin Plasma, Tissue Culture Media. Dried fecal samples require a solid-phase extraction step using the Steroid Solid Extraction Protocol (provided separately). Samples should be processed and stored according to the included kit booklet to ensure assay accuracy.
The minimum detectable dose (sensitivity) of this Cortisol EIA Kit is 17.3 pg/ml. The quantification range spans 100–3,200 pg/ml. Samples falling outside this range should be diluted (high) or concentrated (low) accordingly.
Total assay time is approximately 2–3 hours. Key incubation steps include: antibody/sample incubation (90 Minutes), conjugate incubation, and TMB substrate development. Refer to the Kit Booklet for the precise protocol timeline.
A standard 96-well microplate spectrophotometer (ELISA plate reader) capable of measuring absorbance at 450 nm is required. Additional equipment includes a microplate washer or multichannel pipette, pipettes, and a timer. All reagents are supplied within the kit.
Yes. This kit is species-independent—the assay detects Cortisol based on structural recognition rather than species-specific antibodies. It is validated for use in human, murine, avian, and other mammalian matrices including dried fecal extracts commonly used in non-invasive stress biology studies.
Intra-assay precision (within-run CV) is <10% across tested concentration ranges. Three or more samples of known concentration are tested in ≥20 replicates per lot to establish lot-specific precision certificates. Refer to the Kit Booklet for lot-specific CV data.
This product may be available in custom quantities, alternative formulations, or with additional quality certifications to meet specific experimental requirements. Contact our scientific team through the BioHippo product page to discuss custom sizing, bulk ordering, and specialized packaging options. Special pricing may be available for volume orders and institutional customers.
