The application of infrared and Raman spectroscopic techniques to the analysis of urinary calculi is reviewed and their relative efficiency and adaptability to routine analysis are discussed. Using the classification of urinary calculi based on their main constituents, infrared and Raman spectra of calcium oxalates, phosphates, uric acid, urates, and cystine are reported. Some characteristic bands are suggested as useful for analytical purposes. References to other constituents such as drugs are included. Although this review is aimed principally at human stones, it also extends to literature references dealing with urinary calculi from canine, feline, and equine animal species. © 1997 John Wiley & Sons, Inc. Biospectroscopy 3: 331–346, 1997

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Vibrational, N M R and dynamic N M R spectra, considered together with the results of theoretical studies, provide a complete and fairly accurate quantitative picture of the isomerism affecting the nitroenamines R2R3N-C( 1 ) R'=C(2) H-NO, (R' = H, Me). The compounds with primary or secondary amino groups ( R2 and/or R3 = H) exist as solvent-dependent equilibrium mixtures of the intramolecularly hydrogenbonded Z-form and the €-form; the latter isomer can adopt the Z and/or the € conformation around the C(1)-N single bond when R2 # R3. The compounds with a tertiary amino group exist solely in the Eform. Vibrational couplings occur inside the mesomeric system leading to an IR strong (medium or weak Raman) 'enamine' band at 1650-1550 cm-', the result of the asymmetrical coupling of the C=C and C( 1 )-N stretching modes, and when R' and R2 = H, with contributions of the in-plane N-H and C( 1 )-H bending modes. The N-0 stretchings do not contribute to the enamine band, but couple with other vibrations to give a weak IR and Raman band at 1530-1 480 cm-', with a main contribution of the v,(NO,), and a strong IR (medium or weak Raman) band, mainly v,(NO,), at 1280-1230 cm-'. The energy barriers to rotation around the C(l)=C(2) and C(1)-N bonds, and the AGt values for the ionization of the N-H group, indicated that the €e Z isomerization takes place by a thermal mechanism with dipolar transition state, with the contribution, in some of the compounds with an NH group, of an anionic mechanism.Nitroenamines have attracted interest because of their potential use in organic synthesis and their biological a ~t i v i t y . ~ A knowledge of the isomerism and electron distribution inside these mesomeric systems is of paramount importance in understanding their properties and reactivity. As in similar push-pull ethylenes, spectroscopic techniques combined with theoretical studies can provide information on these matters, and we have previously reported on the NMR and vibrational spectra of 3-amino-2-nitroacrylic (1) and 3-amino-2-nitro-NO2 C02Me R2 R3N C( R1 ) ==( 1 R ' = H 2 R L M ~ NO2 R2R3NC( R 1 ) 7 ( 3 R ' = H 4 R'=Me * The symbols indicate, in the order shown, the configuration around the C(l)=C(2) bond and the conformation around the C(1)-N single bond.

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Objectives:To investigate the presence of calcium urate, sodium, potassium and calcium in 'pure' uric acid calculi. Methods: Ten spontaneously passed uric acid urinary calculi have been examined by stereoscopic microscopy, infrared spectroscopy, scanning electron microscopy and energy dispersive X-Ray analysis. Results: The analysis of selected uric acid calculi revealed the presence of a near-pure calcium urate in two cases and of calcium enriched urate zones in all of the samples. Furthermore, in some cases complex urates containing sodium, potassium and calcium in different proportions appeared on the surface of the uric acid calculi studied , potassium being generally predominant. Ammonium urate was not detected. Conclusions: Most urinary uric acid calculi are not pure in composition. 'Complex urates', sodium, potassium and calcium were found together in various proportions in many areas of uric acid stones.

The chemical constituents of 34 feline urinary calculi and five urethral plugs were analysed by infrared spectroscopy. The analysis revealed that 18 (52.9 per cent) of the calculi contained magnesium ammonium phosphate hexahydrate (struvite) as the major component; 10 (29.4 per cent) contained complex ammonium urates (three of them also containing calcium phosphate, mainly on the surface); three were composed of calcium phosphates and three were composed mainly of calcium oxalate mono and dihydrates. The urethral plugs were composed primarily of struvite, but also contained large amounts of organic matter. The examination of 16 selected samples by scanning electron microscopy and electron dispersive x-ray analysis revealed that their crystalline structures were similar to those of canine stones.