A comparative study of two methods of urine preservation

In preparation for the conduct of biochemical experiments in the Skylab Orbital Workshop a study was performed on the stability of various chemical constituents in urine in 2 different techniques for preservation and storage. Urine samples were either vacuum dried or frozen and maintained in storage at −20° for periods of up to 10 weeks. The urinary constituents studied included aldosterone, antidiuretic hormone, epinephrine, norepinephrine, urea, nitrogen, creatinine, hydroxyproline, 17-hydroxycorticosteroids, calcium, sodium, potassium, chloride, magnesium and phosphate. Some degradation of urinary compounds was observed after both treatments. The rate and variability of destruction following the vacuum drying treatment, however, was greater than for freezing. It was concluded that only the freezing treatment could be used to preserve with predictable loss the urinary samples which would be returned to earth following the conclusion of each Skylab flight.