Identification and quantitation of phenylalanine, tyrosine and dihydroxyphenylalanine in the thoracic nervous system of the locust, Schistocerca gregaria, by gas chromatography-negative-ion chemical ionisation mass spectrometry.
Phenylalanine, tyrosine and dihydroxyphenylalanine (DOPA) were identified unambiguously and quantitatively determined in single ventral thoracic nerve cords from the locust, Schistocerca gregaria, by gas chromatography-negative-ion chemical ionisation mass spectrometry. Deuterium-labelled analogues of each compound were added to a single ventral thoracic nerve cord in hydrochloric acid; the tissue was homogenised and the suspension centrifuged. The remaining hydrochloric acid was eliminated azeotropically by repeated additions of acetonitrile followed by evaporation under a stream of nitrogen and the resultant residue derivatised by reaction with hexafluoroisopropanol and pentafluoropropionic anhydride. Under negative-ion chemical ionisation conditions, the hexafluoroisopropanol-pentafluoropropionyl derivatives produced characteristic ions which were sufficiently abundant to be suitable for selected-ion monitoring. This method is highly specific and gave a limit of detection below the nanogram level. The amounts of phenylalanine, tyrosine and DOPA in a single ventral thoracic nerve cord were, respectively, 194 +/- 81, 347 +/- 88 and 11 +/- 11 ng per tissue.
Macfarlane
R G
RG
Department of Pharmacy, University of Strathclyde, Glasgow, Scotland, U.K.
Midgley
J M
JM
Watson
D G
DG
Evans
P D
PD
D000818:Animals; D003903:Deuterium; D004295:Dihydroxyphenylalanine / Q000032:analysis*; D005260:Female; D005466:Fluorocarbons; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006110:Grasshoppers; D008297:Male; D009420:Nervous System / Q000737:chemistry*; D010649:Phenylalanine / Q000032:analysis*; D020005:Propanols; D013909:Thorax; D014443:Tyrosine / Q000032:analysis*; D006845:Hydrocarbons, Fluorinated
D003903:Deuterium; D004295:Dihydroxyphenylalanine; D005466:Fluorocarbons; D010649:Phenylalanine; D020005:Propanols; D014443:Tyrosine; C068048:pentafluoropropionic anhydride; C001337:hexafluoroisopropanol; D006845:Hydrocarbons, Fluorinated