DETERMINATION OF PROSTAGLANDINS IN THE COLOSTRUM OF DAIRY-CATTLE BY THERMOSPRAY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY

A thermospray high-performance liquid chromatography-mass spectrometry (TSP HPLC-MS) method is described for the analysis of prostaglandins (PGs) E1 and E2, which have several physiological actions at the trace level. HPLC separation was carried out on a reversed-phase column by using 50 mM ammonium acetate (pH 4.5)-acetonitrile (7:3, v/v) as the m obile phase at a flow rate of 1.0 ml/min. In MS detection, the vaporiz er temperature was set at 220-degrees-C and the ion-source block tempe rature at 264-degrees-C. The mass spectra obtained from PGs typically exhibited the [M+NH4]+ ion (5 to 30% relative intensity) and several f ragment ions due to sequential losses of water from both the [M+H]+ an d [M+NH4]+ ions. PGE1 (46.9 ppb) and PGE2 (1.9 ppb) in the colostrum o f dairy cattle were identified and quantitated. The PGE1 concentration in the colostrum and mature milk of dairy cattle showed a similar pat tern to that in humans.