Nicolet is50 ftir nir spectrometer

Sample in FTIR assay was 10 mg of rosmarinic acid standard, 10 mL of NADES betain-urea liquid and 10 mL of 1% mixture of rosmarinic acid standard in NADES betain-urea. The FTIR test was carried out using the Thermo Scientific - Nicolet iS50 FTIR + NIR Spectrometer provided by the ILRC laboratory of the University of Indonesia. The FTIR spectra was observed structural changes of rosmarinic acid due to solvation in NADES.

Menadione of high purity (>98%) purchased from Sigma Aldrich (St. Louis, MO, USA) was used as received. MIR spectra were measured by attenuated total reflection (ATR) and diffuse reflectance (DRIFT) techniques on a Nicolet iS50 FT-IR/NIR spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) using KBr beamsplitter and DTGS/KBr detector. IR spectra were measured in the 4000–400 cm⁻¹ range with a resolution of 2 cm⁻¹ and 512 scans were accumulated. DRIFT spectra were measured with the Collector accessory. The sample was mixed with dry KBr to obtain approx. 2% (w/w) solid solution. The sample was prepared directly before the spectral measurements. ATR-IR spectra were acquired by ATR Smart Golden Gate accessory (single reflection, 45° incident angle) with diamond internal reflection element (IRE). Next, the spectra were subjected to ATR correction using the refractive index of the IRE and the sample. NIR spectra were measured on Nicolet iS50 spectrometer (Thermo Fisher Scientific, Waltham, MA, USA), with CaF₂ beamsplitter and DTGS/KBr detector. The spectra were collected in the 10,000–4000 cm⁻¹ range with resolution of 4 cm⁻¹ and 256 scans were accumulated.