Evaluation of saliva collection devices for the analysis of steroids, peptides and therapeutic drugs

The recovery of steroids, peptides and therapeutic drugs from commercial saliva collection devices was investigated. Saliva, spiked with defined concentrations of the analytes was applied to the Quantisal®, three different Salivettes®, and the Saliva-Collection-System® to investigate effects of volume, exposure time and temperature on the recovery. Additionally, saliva was collected from healthy subjects with the same devices.It was found that glucocorticoids can be measured very well from samples obtained with the synthetic fiber Salivettes® and the Quantisal® (80–100%). For androgens, the Quantisal® and the Saliva-Collection-System® reached recoveries >80%. The Quantisal® and polyester Salivette® achieved best recoveries (>80%) for peptides. The results for the cotton Salivette® were extremely poor for melatonin, insulin or IL-8 (<20%).The results from the spike-recovery experiments were confirmed by samples collected from healthy volunteers. For most therapeutic drugs the synthetic fiber Salivettes® achieved best recoveries of 100 ± 10%. Longer exposure of saliva on the collection devices must be avoided for most of the analytes, due to their limited stability and increased adsorption.In conclusion, no device is suitable for all of the salivary compounds. Strict pre-analytical precautions must be considered (e.g. immediate processing of the sample) to guarantee reliable analytical results.