Solubility of L-Cystine in NaCl and artificial urine solutions
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L-Cystine is the least soluble of the naturally occurring amino acids, and cystine stones, caused by a genetic disorder, account for between 1-4% of all urinary stones. Since the concentration of cystine in urine is the only factor related to the stone formation, a proper knowledge of cystine solubility in urine is necessary. Some research groups have already reported on the solubility of L-cystine, but the results are scattering. In this work, a systematic investigation of cystine solubility under conditions most pertinent to urolithiasis was carried out. The solubilities of L-cystine were measured at 25.0 and 37.0°C, from pH 1 to 9, and in different media including (i) 0.300 mol • dm 3 NaCl solution and (ii) artificial urine solutions. The Joint Expert Speciation System (JESS) computer package and selected protonation constants of cystine reported in literature were used to model the solubilities of cystine. Excellent agreement was obtained between the experimentally determined solubility data and computer modelling of cystine solubility. The results of this work show that the presence of inorganic components has little influence on the solubility of cystine in urine.
|Publication Type:||Journal Article|
|Copyright:||© Springer Verlag 2000|
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