The aim of this study was to optimize Fourier transform infrared (FTIR) spectroscopy and multivariate calibration for quantitative analysis of Acid orange 7 (AO-7) and Sudan II (S-II) in blusher product. Twenty one sample series were made by adding known concentrations of AO-7 and S-II in placebo of blusher cosmetics products. To know the actual values of AO-7 and S-II, both analytes were determined using reference method of HPLC equipped with photo-diode array (PDA) detector at 300-650 nm. The separation of AO-7 and S-II was performed using C18 column at 40oC with mobile phase of acetonitrile-water in gradient elution program. Quantitative analysis of AO-7 and S-II using FTIR spectrophotometer was performed using attenuated total reflectance (ATR) mode. The correlation between actual values of AO-7 and S-II as determined using HPLC and FTIR predicted values was facilitated with multivariate calibrations. The selection of calibration models was relied on highest R2 and lowest levels of RMSEC, RMSEP and RMSECV. The optimization results showed that FTIR spectra-partial least square calibration using wavenumbers of 3450-2400 cm- and 6 factors offered the highest R2 value (R2 > 0.98) and lowest errors. FTIR spectra-PLSR could be used to predict AO-7 and S-II in blusher product with the main advantage of its simplicity, rapid, and minimum sample preparation.
Key words: Acid orange 7, Sudan II, HPLC; FTIR multivariate, PLSR, PCR, Blusher.
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