Nicolet 6700 ft ir spectrometer

For FT-IR spectroscopy, PFSV-2 was mixed with KBr and the spectra were recorded from 4,000 to 500 cm⁻¹ with a Nicolet 6700 FT-IR spectrometer (Thermo Electron Corp., Waltham, MA, USA).
The monosaccharide composition of PFSV-2 was determined by high-performance anion-exchange chromatography (Dionex LC₃₀ equipped with a CarboPac^TM PA20 column and a pulsed amperometric detector) (12 (link)).
The molecular weight of PFSV-2 was determined by high-performance gel permeation chromatography (HPGPC), using a refractive index detector and a multi-angle laser scattering detector according to the reported method (13 (link)).
The methylation of PFSV-2 was performed according to the method of Huang et al. (14 (link)). After methylation, derivatives for gas chromatography-mass spectrometric analysis were obtained by hydrolysis, reduction and acetylation of the completely methylated polysaccharide.
The freeze-dried PFSV-2 (50 mg) was dissolved in 500 μl of deuterium oxide (D₂O). ¹H, ¹³C, ¹H-¹H COSY, NOESY, HSQC and HMBC NMR spectra of PFSV-2 were obtained using a Bruker AV-400 MHz (¹³C) spectrometer, using tetramethylsilane (TMS) as an internal standard according to a previously published method (15 (link)).

X-ray diffraction (XRD) information, analyzing the effect of pretreatment and cationization on fiber crystal structure, was acquired from an X-ray diffractometer (Rigaku D/MAX2400, Rigakub Co., Tokyo, Japan) using Cu Ka1 radiation. The Nicolet 6700 FTIR spectrometer (Thermo Electron Co., Waltham, MA, USA) was utilized to collect the Fourier-transform infrared spectroscopy of all the samples, to analyze the effect of pretreatment on fiber crystal type and crystallinity. To investigate the distinction of surface morphology among the raw fibers, pretreated fibers, and cationic fibers, microstructure images of the selected fibers were observed using scanning electron microscopy (SEM; JSM-5600LV, JEOL Co., Tokyo, Japan). The water contact angle tester (SL250, USA KINO Industry Co., Ltd., Shanghai, China) was used to illustrate the influence of the investigated pretreatment and cationization methods on the water absorption capacity of the fibers.

Optical rotations were determined using a JASCO P-2000 polarimeter (JASCO International Co., Ltd., Tokyo, Japan). IR spectra were measured with a Nicolet 6700 FT-IR spectrometer (Thermo Electron Corp., Waltham, MA, USA). NMR data analysis was performed with a JNM-ECA 600 MHz spectrometer (Jeol Ltd., Tokyo, Japan) coupled with a 5 mm CPTCI cryoprobe (Bruker, Germany). For column chromatography, silica gel (Merck KGaA, Darmstadt, Germany, particle size 63–200 μm) and RP-18 (Merck KGaA, particle size 75 μm) were used. Sephadex LH-20 from Sigma-Aldrich (St. Louis, MO, USA) was also used. Thin-layer chromatography (TLC) was conducted using silica gel 60 F₂₅₄ and RP-18 F₂₅₄ plates from Merck KGaA, Darmstadt, Germany. High-performance liquid chromatography (HPLC) was carried out using a Gilson system with a UV detector (at 201 and 254 nm) and an Optima Pak C₁₈ column (10 × 250 mm, particle size 5 μm, RS TECH Co., Ltd., Chungcheongbuk-do, Korea).

Cdots were synthesized using a modified hydrothermal method described previously.^[40] In a typical experiment, 2 g of citrate (Sigma‐Aldrich, USA) and 1 g of l‐tryptophan (L‐Trp) (Sigma‐Aldrich, USA) were dissolved in 30 mL of deionized water and stirred for 1 h to form a homogeneous solution. The solution was heated at 160 °C for 2 h in a polytetrafluoroethylene (Teflon)‐lined autoclave reactor (Autoclave, USA), and the resulting homogeneous dark brown solution was allowed to cool to room temperature. The solution was centrifuged at 12 000 rpm for 10 min to remove unreacted precipitates. Excess citric acid and L‐Trp were removed by repeated dialysis (1000 Da cutoff) against deionized water for 2 d. Dry Cdots were collected by freeze‐drying and weighed and dissolved in phosphate‐buffered saline (PBS) for further use. Cdot size and morphology were characterized by using a JEM‐2100 transmission electron microscope (JEOL, Japan). Cdot UV–vis absorption spectra were collected using a Varian Cary 50 UV–vis Spectrophotometer (Varian, Inc., USA). Cdot FTIR spectra were collected using a Nicolet 6700 FTIR spectrometer (Thermo Electron Corporation, USA).

For FTIR spectroscopic measurements, a sample of the isolated and purified compound (~1 mg) was dissolved in a minimal volume (~10 μL) of MilliQ water, placed (using a microsyringe) as a thin film on a clean flat ZnSe disk (CVD-ZnSe, “R’AIN Optics”, Dzerzhinsk, Russia; ø 1 cm, thickness 0.2 cm) and dried in a drying cabinet at 45 °C (~20 h). Transmission FTIR spectroscopic measurements were performed on a Nicolet 6700 FTIR spectrometer (Thermo Electron Corporation, Beverly, MA, USA; DTGS detector; KBr beam splitter) as reported earlier [46 (link)] (with a total of 64 scans (resolution 4 cm⁻¹) against the ZnSe disk background; spectra were manipulated using the OMNIC software (version 8.2.0.387) supplied by the manufacturer of the spectrometer). The baseline was corrected using the “automatic baseline correct” function, and the spectra were smoothed using the standard “automatic smooth” function of the software which uses the Savitsky–Golay algorithm (95-point moving second-degree polynomial). The FTIR spectroscopic measurements were repeated three times and were well reproducible.

Fourier transform
infrared (FTIR) spectral data of the electrolyte samples were obtained
by using a Nicolet 6700 FTIR spectrometer (Thermo Electron) at room
temperature. To remove the interference of H₂O and CO₂, nitrogen was blown through the FTIR spectrometer and sample
chamber. All FTIR spectra were fitted by the Voigt function consisting
of Gaussian and Lorentzian functions in Origin95 software.

Optical rotations were recorded on a JASCO P-2000 polarimeter (JASCO International Co., Ltd., Tokyo, Japan). IR data were collected using a Nicolet 6700 FT-IR spectrometer (Thermo Electron Corp., Waltham, MA, USA). ECD spectra were obtained using Chirascan Plus (Applied Photophysics Ltd., Surrey, United Kingdom). A Waters Xevo G2 QTOF MS spectrometer (Waters Co., Milford, MA, USA) was used for high-resolution electrospray ionization mass spectrometry (HRESIMS) values. Semipreparative HPLC experiments were performed using a Gilson HPLC system with a 321 pump and a UV/VIS-155 detector. A Phenomenex Phenyl-Hexyl column (10 × 250 mm, 5 μm particle size, USA) was used as the HPLC column. The NMR spectra for 1D (¹H and ¹³C) and 2D (HSQC, HMBC, NOESY, and ROESY) were measured on a Varian Unity Inova spectrometer at 500 MHz (Agilent Technologies, Santa Clara, CA) and an AVANCE spectrometer at 800 MHz (Bruker, Germany). YMC*Gel ODS-A and Sephadex LH-20 were used for column chromatography. Thin-layer chromatography experiments were performed with silica gel 60 F₂₅₄ and RP-18 F₂₅₄ plates. A Gilson semi-Prep HPLC system was composed of a flow rate of 3 mL/min and UV detection at 201 and 254 nm. All solvents (Dae Jung Pure Chemical, Siheung, Korea) for extraction and isolation were of analytical grade.