Chemical and structural analysis of gallstones from the Indian subcontinent.

Representative gallstones from north and southern parts of India were analyzed by a combination of physicochemical methods: X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), CHNS analysis, thermal analysis and Nuclear Magnetic Resonance (NMR) spectroscopy (1H and 13C). The stones from north Indian were predominantly consisting of cholesterol monohydrate and anhydrous cholesterol which was confirmed by XRD analysis. FTIR spectroscopy confirmed the presence of cholesterol and calcium bilirubinate in the south Indian gallstones. EDX spectroscopy revealed the presence of carbon, nitrogen, oxygen, calcium, sulfur, sodium and magnesium and chloride in both south Indian and north Indian gallstones. FTIR and NMR spectroscopy confirmed the occurrence of cholesterol in north Indian gallstones. The respective colour of the north Indian and south Indian gallstones was yellowish and black. The morphology of the constituent crystals of the north Indian and south Indian gallstones were platy and globular respectively. The appreciable variation in colour, morphology and composition of south and north Indian gallstones may be due to different food habit and habitat.