Determination of Cyclohexanone, Cyclohexanone Oxime and Nitrocyclohexane in Hydroxylamine Hydrochloride Oximation Reaction Solution by GC

A method for simultaneous determination of cyclohexanone, cyclohexanone oxime and nitrocyclohexane in hydroxylamine hydrochloride oximation reaction solution by gas chromatography (GC) was developed. Hydroxylamine hydrochlonde oximation reaction solution of 0.1 g was added to 5.0 mL internal standard solution of cyclopentanone oxime, and diluted to 100 mL by anhydrous ethanol. The optimized conditions of GC were found. Kromat KB-624 chromatographic column (30 m×0.32 mm, 1.8 μm) was used to separate the targets and other impurities by temperature programmed method, with the flow rate of 2.0 mL·min^-1 and the split ratio of 100∶1. Internal standard method was applied to quantification with cyclopentanone oxime as internal standard substance. As shown by the results, the resolutions of the chromatographic peaks of cyclohexanone, cyclopentanone oxime, cyclohexanone oxime and nitrocyclohexane with their adjacent components were all greater than 2.0. Linear ranges of the standard curves of 3 compounds were 1.0-1 000.0 mg·L^-1, with detection limits (3S/N) of 0.02 mg·L^-1. Recovery test was made by standard addition method, giving results of 3 compounds in the range of 97.5%-102%, with RSDs (n=6) of the determined values ranged from 1.5% to 4.5%. This method was used to determine 8 batches of hydroxylamine hydrochloride oximation reaction solution, and the mass fractions of cyclohexanone, cyclohexanone oxime and nitrocyclohexane were 5.51%-55.32%, 11.86%-88.52% and 0.10%-80.62%, respectively.