# Magnetic Particle-Based Automated Chemiluminescence Immunoassay for the Determination of Hydrocortisone Residues in Milk

## TL;DR

This study introduces a fast and accurate immunoassay for detecting hydrocortisone in milk, which is important for food safety and human health.

## Contribution

A novel magnetic particle-based chemiluminescence immunoassay with automation for rapid hydrocortisone detection in milk is developed.

## Key findings

- The assay completes in 12 minutes with a detection range of 13.09–261.71 μg/L and a limit of detection of 4.94 μg/L.
- Spiked milk sample recoveries ranged from 85.85% to 100.30%, showing strong correlation with LC-MS/MS results.
- The method is stable, precise, and free from cross-reactivity with structural analogues.

## Abstract

Hydrocortisone is a typical glucocorticoid commonly used in livestock production; however, its overuse can result in hormone residues in milk. Long-term consumption of such milk may lead to a series of health issues. Therefore, the timely and rapid detection of hydrocortisone in milk is crucial for protecting human health. In this study, a magnetic particle-based direct chemiluminescence immunoassay (MP-DCLIA) incorporating a streptavidin–biotin signal amplification system was developed for the rapid and high-throughput detection of hydrocortisone in milk. Automated operations reduce human error and enhance the accuracy and repeatability of tests. The assay can be completed in 12 min with a linear detection range of 13.09–261.71 μg/L, a limit of detection (LOD) of 4.94 μg/L, a limit of quantification (LOQ) of 14.84 μg/L, and intra- and inter-batch variations of less than 5%. The method demonstrated stability and exhibited no cross-reactivity with structural analogues. Spiked recoveries of milk samples ranged from 85.85% to 100.30%, with results strongly correlating with those obtained from LC-MS/MS. The MP-DCLIA offers rapidity, high efficiency, stability, and precision, making it a promising tool for practical testing applications.