Background: Strong mineral acid is the most commonly used preservative
for measuring urinary free catecholamines. Leakage of corrosive acid is a safety
hazard. The use of formate buffer as a safer alternative was studied.
Methods: Twenty-two urine specimens from post-operative patients were
collected and preserved in 0.5 M hydrochloric acid or 0.75 M formate buffer. The
specimens were stored at 4°C or -70°C, respectively. The free catecholamine content
was measured at regular intervals by high-performance liquid chromatography for 6
months.
Results: The preservation capability of formate buffer was equivalent to
that of hydrochloric acid. Deep-freeze storage offered additional protection
independent of the preservative used.
Conclusion: The results of this study demonstrate that formate buffer,
compared to the most popularly used strong mineral acid solution, is an equally
effective preservation for urinary free catecholamines. The less acidic nature of
formate should invite fewer unpleasant incidents and safety hazards.
