Direct Content Determination of Metronidazole Tablets by Raman Spectroscopy

OBJECTIVE To establish the direct content determination method of metronidazol tablets by raman spectroscopy. METHODS By selecting standard raman spectrum of metronidazol from standard spectrum database in portable laser reman spectrometer and then selecting proper characteristic peak from standard raman spectrum(200~3000 cm^-1) of metronidazol, using of methodological verification including linear, repeatability and recovery tests, the direct content determination method of metronidazol tablets by raman spectroscopy was established. The metronidazol tablets without any pretreatment were taken from bottles for content determination directly by using of reman spectroscopy and their determination results were compared with that of HPLC. RESULTS The characteristic peak at 1 533 cm^-1 in the standard raman spectrum of metronidazol was not affected by supplements, with best exclusivity and stability and proper to be used for its content determination. In the direct content determination method of metronidazol tablets, the good linear relationship was achieved in the range of 26-1000 mg·g^-1, its linear equation was y=7.989 5x+0.3948 with correlation coefficient of 0.9994 and its detection and quantitative limits were 10 and 26 mg·g^-1 respectively. The determination RSDs of same-day and between-days of high, middle and low contents were 0.08%, 0.12%, 0.11% and 0.47%, 0.48%, 0.65% respectively. The RSD of 6 repeated determinations of the same metronidazol tablet was 0.41%. In recovery test, the average recoveries of reman spectroscopy in determinating high, middle and low contents were 99.87%, 100.2%, 100.1%, RSDs were 0.04%, 0.07% and 0.18% respectively. The scope and max of relative prediction error of reman spectroscopy 1 were -0.7%-0.5% and 0.7% and that of reman spectroscopy 2 were -0.7%-1.1% and 1.1%. CONCLUSION The method is fast and simple, which can achieve nondestructive testing of metronidazole tablets.