Quantitative analysis of alcohol, sugar, and tartaric Acid in alcoholic beverages using attenuated total reflectance spectroscopy.

Mid-infrared (MIR) spectroscopy in attenuated total reflectance (ATR) mode was used for quantifying ethanol, sucrose, and tartaric acid in alcoholic beverages. One hundred synthetic samples were prepared with different ethanol, sucrose, and tartaric acid concentrations. Experiments were carried out on Bio-Rad 175 C FTS using an ATR accessory. Spectra were recorded in the wavelength region 600-4000 cm-1. Calibration was performed using partial least squares (PLS) algorithm. Commercially available alcoholic beverages (gin, rum, vodka, etc.) were experimented and concentration of ethanol in these samples was predicted using the developed calibration model. Chemical analysis of these commercial samples was carried out in order to compare the results. The agreement between ATR results with those of chemical analysis revealed good reliability and repeatability of the technique used.

Binding of 5,5-diphenylhydantoin with erythrocyte membrane: local lateral order parameter and strong interaction with phospholipid head groups.

We have studied the interaction of 5,5-diphenylhydantoin (5,5-dph), an anticonvulsant drug, with erythrocyte membrane lipids and proteins using IR spectroscopic technique. The local lateral order parameter, which is directly related to the lipid packing density, has been found to be elevated due to 5,5-dph binding. This increase has been accounted for on the basis of relaxation of local discontinuity in orientational order (defects). The transition towards an ordered structure is further supported by our experimental results which exhibit a decrease in the hydrocarbon chain mobility. The reorganization of the polar head groups due to 5,5-dph-lipid interaction leads to the absence of the bands at 1150 cm-1 (C-O stretch or C-O-C antisymmetric stretch) and 1085 cm-1 (C-O-P stretch or PO2- symmetric stretch). These bands are associated with the phospholipid head groups in erythrocyte membrane. Significant intensity changes in amide I (1650 cm-1) and amide II (1520 cm-1) have been explained using the concept of transition dipole moment coupling between C-N and N-H vibrational modes of amide II.

Conformational changes in the IgG molecule of lepromatous sera using laser Raman spectroscopy.

In the present work we report our studies on IgG separated from the serum of lepromatous patients and non-lepromatous leprosy cases using Laser Raman Spectroscopy. Striking spectral changes in LL cases have been observed in the following special regions: (a) the amide I and III, (b) the S-S and C-S stretching (c) the skeletal bending and (d) skeletal stretching regions. These changes indicate a decrease in the amount of beta-structure and a transition towards alpha-helical conformation.