Several configurations of the Saliva Collection Kit have been developed. Each consists of a cloth (Nomex) pouch in which a quantity of collection vials is secured by means of foam inserts or elastic straps. Each vial contains a sterile dental cotton roll. The vials are labeled and color-coded, and contain a space for the crewmember to record the time at which the sample was taken. The kits also contain a marking pen, a pair of tweezers to facilitate removal of the cotton roll from the vial, and strips of an inert rubbery film (Parafilm) that the crewmembers can chew to stimulate salivation if necessary. During use, the subject removes the cotton roll, places it in his/her mouth until it is saturated with saliva, and then returns it to the vial.
Two different types of collection vials are used. For studies in drug pharmacokinetics, plastic "Salivette" vials (developed for NASA by Sarstedt) are used. The Salivette is a test-tube system designed for standardized hygienic collection of mixed saliva in the mouth. After flight, each vial is placed in a plastic adapter that allows it to fit into a standard centrifuge test-tube holder. The saliva samples are then removed from the vials by centrifugation and stored for subsequent analysis. For studies involving the calculation of total body water, saliva samples are typically taken after ingestion of a tracer, such as water labeled with "heavy oxygen" and deuterium (heavy hydrogen). In these cases, glass lyophilization vials are used in place of the plastic Salivettes. This is because the concentrations of isotopes involved are extremely low, and the plastic vials are just porous enough that isotope transport through the vial walls is possible. Thus, the samples could be altered by evaporation of the tracer dose. When the glass vials are used, each vial is wrapped in protective Teflon shrink-wrap and adhesive tape. This reduces the chance of breakage and would contain the glass fragments if breakage did occur. The Saliva Collection Kits are developed by the NASA Medical DSO Flight Projects Laboratory.