Short-term and long-term storage stability of heparin plasma ammonia

    loading  Checking for direct PDF access through Ovid

Abstract

Aims

Ammonia is an extremely unstable analyte and requires special attention during sampling, transport and storage. The aim of this study was to evaluate the stability of ammonia in lithium-heparin plasma during short-term (at +4°C) and long-term (at −20°C) storage.

Methods

Twenty plasma samples were used for short-term stability assessment. Each sample was divided into five aliquots and stored in stoppered tubes at +4°C, for 1, 2, 3, 4 and 24 h from initial testing. Fifteen plasma samples were used for long-term stability assessment. Each sample was divided into eight aliquots and stored in stoppered tubes at −20°C for 3, 24, 48 h and 1, 2, 4, 8 and 12 weeks from initial testing. Ammonia concentration was determined on a Beckman Coulter AU2700 chemistry analyser using Randox ammonia enzymatic UV method. Bias was calculated from initial value for each time point and compared with quality specifications defined by Royal College of Pathologists of Australasia.

Results

The average bias exceeded the total allowable error after storage of samples for 1 h at +4°C and 3 h at −20°C.

Conclusion

Ammonia is not stable during storage at +4°C and −20°C in lithium-heparinised plasma and should therefore be analysed immediately.

Related Topics

    loading  Loading Related Articles