Nondestructive prediction of oren extract powder, a herbal medicine, in suppositories by chemometric near-infrared spectroscopy

Near-infrared (NIR) spectroscopy combined with chemometrics has been utilized in predictions of natural medicine content without destroying samples. Suppositories (oren powdered extract content 0, 0.5, 1.0, 2.5, 10, 12.5, and 15%) were produced by mixing oren powdered extract with macrogol mixture consisting of 1 part macrogol 1500 and 2.5 parts macrogol 4000 at 54°C, and pouring the melt mixture into a plastic container. NIR spectra of the 10 prepared samples were recorded 10 times, and a total of 100 spectra were randomly divided into two data sets, one for calibration and the other for validation. The calibration model for the oren content of the suppository was calculated based on NIR spectra using a partial least-squares regression analysis after pre-treatment (smoothing and the multiplicative scatter correction). The relationship between the actual and predicted values for calibration and validation models had a straight line with correlation coefficients of 0.9936 and 0.9898, respectively. The regression vector result of the calibration model indicates that the peaks at 6945, 5747, and 5160 cm⁻¹ in the regression vector were consistent with those in oren powder extracts. NIR spectroscopy combined with chemometrics offers promise as a method of predicting the oren powder content in suppositories without destroying the samples.