Data from: Long-term storage effects in steroid metabolite extracts from baboon (Papio sp.) faeces – a comparison of three commonly applied storage methods

1. The measurement of steroid hormone metabolites from faeces in wild animal populations is a powerful, non-invasive tool in behavioural endocrinology of all major vertebrate taxa. However, because such research is often done in remote areas with limited infrastructure, storage of samples for hormone analysis over long periods at high temperature is a critical issue in field endocrinology. Previous studies have indicated that storage of alcoholic faecal extracts is more reliable than storage of unprocessed faeces if no freezer is available, but a standard method has not been established yet. 2. We tested the validity of three commonly applied storage conditions - liquid extracts, dried extracts, and extracts placed on solid phase extraction (SPE)-cartridges - to preserve concentrations of glucocorticoid and androgen metabolites from faecal extracts of olive baboons (Papio anubis) at high temperature over one year. 3. Temporal variation in concentrations was detected for all metabolites and all storage conditions, including values measured from the control condition, i.e. extracts stored at 20°C. This suggested that most variation was due to inter-assay variability, corroborated by comparisons of variation in ‘quality controls’ and samples. 4. Compared to frozen control samples, liquid extracts were stable for up to 24 weeks, extracts on SPE-cartridges were stable for up to 50 weeks, while steroid metabolite concentrations in dried extracts decreased slightly over time. 5. If steroid samples have to be stored at ambient temperature, we suggest storage of liquid extracts for up to 24 weeks in a dark and cool place. For longer periods, SPE-cartridges should be applied as evaporation, a potential confound arising with long-term storage of liquid extracts at higher temperatures, is not a problem in this storage condition. Storage of dried extracts is more cost-effective, but may result in small time-dependent changes in steroid concentrations.

1. 对野生动物种群粪便中的类固醇激素代谢物进行检测，是适用于所有主要脊椎动物类群行为内分泌学研究的高效非侵入性手段。然而，此类研究多在基础设施匮乏的偏远地区开展，因此在高温环境下长期保存用于激素分析的样本，是野外内分泌学研究中的核心难题。既往研究表明，在无冷冻设备的条件下，酒精浸泡的粪便提取物保存效果优于未处理的粪便样本，但目前尚未形成统一的标准方法。
2. 本研究针对三种常用保存方案——液体提取物、干燥提取物以及置于固相萃取（Solid Phase Extraction, SPE）小柱上的提取物——开展有效性验证，以评估它们在高温环境下对橄榄狒狒（Papio anubis）粪便提取物中糖皮质激素与雄激素代谢物浓度长达一年的保存效果。
3. 所有代谢物与所有保存条件下均检测到浓度随时间的变化，包括在20℃下保存的对照组提取物的检测结果。这表明绝大多数浓度差异源于批间变异，通过对比质量控制品与样本的变异程度可进一步验证这一结论。
4. 与冷冻对照组样本相比，液体提取物可稳定保存长达24周，置于SPE小柱上的提取物稳定保存时长可达50周，而干燥提取物中的类固醇激素代谢物浓度则随时间出现小幅下降。
5. 若类固醇样本需在室温环境下保存，我们建议将液体提取物置于避光阴凉处，最长可保存24周。若需长期保存，则应采用SPE小柱保存方案：高温环境下长期保存液体提取物可能引发蒸发作用这一潜在混杂因素，而该方案则不存在此问题。干燥提取物的保存成本更低，但可能导致类固醇激素代谢物浓度出现小幅的时间依赖性变化。