In this search an improved gas chromatographic method was used for
identification and typically quantitated for methylparaben(mp) which is used as
preservative in insulin was involved the optimal conditions for
extraction mp from aqueous samples with ethyl acetate ,chloroform ,and toluene as
extractants,then analyzed by gas chromatography(GC).
Effects of each of extractants polarity, aqueous samples pH, phases (organic to
aqueous) ratio, mixing time, polarity of stationary phases, and column temperature
on efficiency of separation and determination of mp. were studied in this work.
Synthetic sample which contained the same contents as a life sample was
tested to omit interferings of other drug additives on analysis results.
The extraction of mp. was (90-91)% with one batch of ethyl acetate and (99-
100)%with two batches of ethyl acetate at pH medium(1.5-2).also the non-polar
stationary phase(OV-101) is the best choice for determining mp by GC.
The concentration of mp. in insulin preparations was within the acceptable
The relative error (R.E) was ± (0,39-1.49)% and relative standard
deviation(R.S.D) was (1.21)% for life samples.