Formate buffer as preservative for urinary free catecholamine measurement

Abstract

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.