Detection of the mineral constituents in human renal calculi by vibrational spectroscopic analysis combined with allied techniques Powder XRD, TGA, SEM, IR imaging and TXRF.

Detection of the mineral constituents in a batch of 310 samples of human urinary calculi (kidney stones-235 and bladder stones-75) combined with a semi-quantitative analysis has been presented on the basis of Fourier Transform based IR and Raman spectral measurements. Some of the observed characteristic IR and Raman bands have been proposed as 'Marker Bands' for the most reliable identification of the constituents. A detailed vibrational spectral analysis combined with a DFT level calculation for the functional groups in Calcium Oxalate Monohydrate (COM), Magnesium Ammonium Phosphate Hexahydrate (MAPH), Calcium Hydrogen Phosphate Dihydrate (CHPD), Penta-Calcium Hydroxy-Triphosphate (PCHT) and Uric Acid (UA) has been proposed. It has been shown that the identified mineral constituents as major or minor components can be deduced from the application of Lambert-Beer law of radiation absorption and results are in agreement with quantitative Spectral Data base. This simple method has the potential to be integrated into the management of Urolithiasis, a process of forming renal calculi in the kidney, bladder and/or urethra. Employment of powder XRD, TGA, SEM, TXRF and IR Imaging techniques has provided additional support for the proposed foolproof identification of the mineral constituents. Among the mineral constituents, Calcium Oxalate Monohydrate, Calcium Oxalate Dihydrate or their mixture account for 85% of the total number of samples; the remaining 15% and 5% samples contain Phosphate and Uric acid stones respectively.

DL-3-Aminoisobutyric acid: vibrational, NBO and AIM analysis of N-H⋯O bonded-zwitterionic dimer model.

A zwitterionic dimer model constructed of inter-molecular -N-H⋯O bonding has been proposed for the solid sample of DL-3-Aminoisobutyric acid consistent with IR absorption and Raman spectral features measured in the 3500-400/50 cm-1. This zwitterionic dimer model in water as solvent has been computed at B3LYP/6-311++G(d,p) and B3LYP-D3/6-311++G(d,p) levels including Grimme's dispersion correction associated with the -N-H⋯O interaction and SCRF-SMD method. Of the several possible monomer and dimer conformational structures, the most stable dimer constructed of two zwitterion monomer units has produced vibrational modes due to the -NH3 + cation and -CO2‾ anion involved in the -N-H⋯O bonding in fair agreement with the observed broad but composite IR modal features near the 3500-2000 cm-1. Except for the frequency of asymmetric stretching mode of the -NH3 + cation, its symmetric and bending modes agree with the observed values. As for the -CO2‾ anion, the frequencies of all of its modes are in good agreement with the experiment. Natural bond orbital (NBO), molecular electrostatic potential (MEP), atoms-in-molecules (AIM) and non-covalent interaction (NCI) analyses have been used to understand electronic characterization of the -N-H⋯O bonding.