Determination of residual organic volatile solvents in methyldopa methyl ester by GC with headspace sampling

OBJECTIVE To determine the content of residulal organic solvents in methyldopa methyl ester.METHODS Headspace GC method was adopted. The GC was equiped with a headspace injector, a flame ionization detector and a 0.32 mm×30 m HP-5 capillary chromatographic column.Nitrogen was the carrier gas. The assay of residual solvents were calculated according to the external standard method.RESULTS The standard curves of methanol,chloroform,1.2-dichloroethane,toluene were linear in the ranges of 13.18-131.80 mg·L 1( r=0.9998),0.30-14.89 mg·L -1(r=0.9984),0.10-10.14 mg·L -1(r=0.9972) and 3.02-302.00 mg·L -1(r=0.9994) and the average recoveries of 98.1%(RSD=2.7%,n=5),95.5%(RSD=4.9%,n=5),89.0%(RSD=7.8%,n=5) and 99.5%(RSD=1.1%,n=5),respectively.CONCLUSION This method is sensitive,accurate,repeatable and easy to operate.