{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T22:21:14Z","timestamp":1790720474565,"version":"4.1.0"},"reference-count":21,"publisher":"BMJ","issue":"4","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["J Clin Pathol"],"accepted":{"date-parts":[[2014,12,15]]},"published-print":{"date-parts":[[2015,4]]},"abstract":"<jats:sec>\n                    <jats:title>Aims<\/jats:title>\n                    <jats:p>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\u00b0C) and long-term (at \u221220\u00b0C) storage.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Twenty plasma samples were used for short-term stability assessment. Each sample was divided into five aliquots and stored in stoppered tubes at +4\u00b0C, for 1, 2, 3, 4 and 24\u2005h 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 \u221220\u00b0C for 3, 24, 48\u2005h and 1, 2, 4, 8 and 12\u2005weeks 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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>The average bias exceeded the total allowable error after storage of samples for 1\u2005h at +4\u00b0C and 3\u2005h at \u221220\u00b0C.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Ammonia is not stable during storage at +4\u00b0C and \u221220\u00b0C in lithium-heparinised plasma and should therefore be analysed immediately.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/jclinpath-2014-202693","type":"journal-article","created":{"date-parts":[[2015,1,19]],"date-time":"2015-01-19T23:13:34Z","timestamp":1421709214000},"page":"288-291","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":19,"title":["Short-term and long-term storage stability of heparin plasma ammonia"],"prefix":"10.1136","volume":"68","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6690-7551","authenticated-orcid":false,"given":"Lora","family":"Dukic","sequence":"first","affiliation":[{"name":"University Department of Chemistry, Medical School University Hospital Sestre milosrdnice, Zagreb, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2391-5241","authenticated-orcid":false,"given":"Ana-Maria","family":"Simundic","sequence":"additional","affiliation":[{"name":"University Department of Chemistry, Medical School University Hospital Sestre milosrdnice, Zagreb, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2015,1,19]]},"reference":[{"key":"2025112108382122000_68.4.288.1","unstructured":"Newman DJ , Price CP . 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