A practical method for storage, preservation and transportation of anuran urine samples using filter paper for hormone analysis

Anurans (frogs and toads) expelled urine when handled and it could provide insights into their physiological status. However, storage, preservation and transportation are often challenging. The study aimed to standardize and validate a field method for short-term storage and preserve of anuran urine samples using Whatman filter papers. To examine the efficacy of storage conditions and type of papers, urinary based enzyme immunoassays were used to measure progesterone and testosterone hormone metabolites. High-Performance Liquid Chromatography was performed and revealed immunoreactive progesterone and testosterone metabolites in the urine samples. Urinary hormone metabolites concentration stored in filter paper at room temperature and control samples stored in -20°C for the same period were similar. Whatman grade 50 was found to be more suitable for storage of hormones than grade 3 paper for the experiments performed. • A cheap and simple storage method for storage of anuran urine in field conditions using filter papers. • Anuran urine could be preserved and transported under ambient conditions without significant changes and loss of hormones. • This method would facilitate the endocrine monitoring of anurans in remote areas where limited logistics are available.