The effect of anticoagulants, enzyme inhibitors and long term storage on the extraction of known concentrations of methionine enkephalin in human plasma.
The stability of methionine enkephalin (M-E) during long term storage was investigated using various anticoagulants and enzyme inhibitors, eg EDTA, heparin, trasylol, citric acid. Plasma was stored for different lengths of time up to six weeks. High pressure liquid chromatography (HPLC) was used to separate and quantify M-E. We found that EDTA, heparin or trasylol per se are ineffective in preserving M-E for short term extraction. Blood collected in chilled heparin tubes with citric acid crystals and the plasma further acidified with hydrochloric acid gave the highest recovery. With storage times up to six weeks further degradation was marked in samples taken in plain tubes but did not occur with tubes containing citric acid crystals and hydrochloric acid.
Saad
E
E
University Department of Obstetrics and Gynaecology, St. James's University Hospital, Leeds.
Tebb
H M
HM
Ashton
K J
KJ
Bromham
D R
DR
D000925:Anticoagulants / Q000494:pharmacology*; D007611:Aprotinin / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D002951:Citrates / Q000494:pharmacology; D019343:Citric Acid; D004355:Drug Stability; D004492:Edetic Acid / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D013997:Time Factors
D000925:Anticoagulants; D002951:Citrates; D004791:Enzyme Inhibitors; D019343:Citric Acid; D004744:Enkephalin, Methionine; D006493:Heparin; D007611:Aprotinin; D004492:Edetic Acid