Determinations of catechols in small volumes of plasma using ion-pair reversed phase liquid chromatography/electrochemistry.
A method with improved sensitivity for detection of catechols (CA) in small volumes of plasma using an ion-pair reversed phase HPLC system with electromechemical detection is presented. Fast isocratic separations were obtained by using 7.5 cm x 4.6 mm (i.d.) reversed phase columns with 3C18 3 micron silica particles. The CA:s L-DOPA, Noradrenaline (NA), Adrenaline (A), Dihydroxybenzylamine (DHBA, i.s.), DOPAC and Dopamine (DA) were separated in less than 4 min. The performance of three different electrochemical cells was compared with respect to hydrodynamic voltammogram, band broadening effect, linearity and detection limit. The sample preparation procedure using alumina extraction of CA:s, was modified to improve recoveries and decrease dilution factors. A modified carbon paste cell (CP-O) gave a response 4-8 times higher than what is previously reported for GC cells. Detection limits were: L-DOPA 80, NA 1.25, A 1.25, DHBA 0.4, DOPAC 1.25 and DA 0.6 pg/injection. Application to plasma from rat and fish (cod) under rest, exercise and stress is reported. The method allows determination of CA:s in small volumes of plasma (less than 500 microliter) obtained several times a day from the same animal even if it is small (less than 1/2 kg), is under rest and parts of the plasma sample are to be used for analysis of other parameters than CA:s.
Ehrenström
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Department of Zoophysiology, University of Göteborg, Sweden.
D015102:3,4-Dihydroxyphenylacetic Acid / Q000097:blood; D000818:Animals; D002395:Catecholamines / Q000097:blood*; D002851:Chromatography, High Pressure Liquid; D004298:Dopamine / Q000031:analogs & derivatives / Q000097:blood; D004837:Epinephrine / Q000097:blood; D005399:Fishes; D007980:Levodopa / Q000097:blood; D008297:Male; D008832:Microchemistry; D009638:Norepinephrine / Q000097:blood; D005082:Physical Exertion; D051381:Rats; D011919:Rats, Inbred Strains; D013312:Stress, Physiological / Q000097:blood
D002395:Catecholamines; D015102:3,4-Dihydroxyphenylacetic Acid; C022133:3,4-dihydroxybenzylamine; D007980:Levodopa; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine