Effect of Different pH Level on the Formation of Calcium Oxalate Homogenous Precipitate in Simulated Urine Environment
Nguyen Ky Anh
The Dewey Schools Tay Ho Tay, Vietnam.
Nguyen Thi Duyen *
The Dewey Schools Tay Ho Tay, Vietnam and Department of Biology, Hanoi National University of Education, Vietnam.
*Author to whom correspondence should be addressed.
Abstract
Kidney stones, particularly those composed of calcium oxalate (CaOx), are a common urological disorder influenced by urinary chemistry, especially pH. This study aimed to investigate how pH affects the precipitation of calcium oxalate in a simulated urine environment at 37 °C. Artificial urine solutions were prepared to reflect typical ionic compositions and adjusted to seven pH levels ranging from 5.0 to 8.0. The formation of precipitate after the reaction between calcium chloride and sodium oxalate was recorded by measuring sediment thickness. The results showed that acidic conditions significantly promoted CaOx precipitation, whereas near-neutral pH (around 6.5–7.0) minimized it. A slight increase in precipitation under alkaline conditions (pH 7.5–8.0) was observed, which may have resulted from the formation of calcium hydroxide due to the supraphysiological calcium concentration used or precipitation of calcium oxalate dihydrate, which is favoured under alkali conditions. These findings support existing research on the inhibitory effect of physiological pH on stone formation and emphasize the importance of maintaining balanced urinary chemistry.
Keywords: Kidney stone, calcium oxalate, citrate, pH, urine, precipitation