Examining cortisol ELISA in dried matrix spots: implications for analyte measurement and stability

Area of Science:

• Veterinary Endocrinology
• Biochemical Analysis
• Animal Physiology

Background:

• Accurate measurement of cortisol is crucial for assessing stress and health in domestic animals.
• Analyzing biological samples in dried form offers advantages in storage and transport.
• Previous methods for dried sample analysis have limitations in recovery and reproducibility.

Purpose of the Study:

• To evaluate the efficacy of strip-dried versus dried spot methods for cortisol analysis in goat samples.
• To compare the accuracy and reproducibility of cortisol measurements in dried samples versus liquid samples.
• To assess the stability of cortisol in dried samples under various storage conditions.

Main Methods:

• Quantitative ELISA was used to analyze cortisol levels in whole blood, plasma, milk, and urine from goats.
• Two drying methods were employed: glass fiber strips (strip-dried) and cellulose membranes (dried spots).
• Cortisol recovery, reproducibility, and stability were assessed for both drying methods and compared to liquid samples.

Main Results:

• Strip-dried samples demonstrated better cortisol recovery and reproducibility than dried spots.
• High correlation (0.90–0.97) was observed between strip-dried and liquid samples for blood, plasma, and urine.
• Cortisol in dried samples remained stable for at least six months at 4°C.

Conclusions:

• Strip-drying on glass fiber strips is a reliable and advantageous method for analyzing goat cortisol.
• This technique offers a practical alternative to liquid sample analysis, with high accuracy and stability.
• The findings support the use of strip-dried samples for routine veterinary diagnostics and research.