Why do wee saturate urine with ammonium sulphate in Rothera's test?

In Rothera's test, urine is saturated with ammonium sulfate to precipitate specific compounds, particularly those containing ketone bodies, such as acetone and acetoacetic acid. The saturation helps to concentrate these compounds, enhancing their detection. This process allows for a clearer identification of ketone bodies, which are indicative of conditions like Diabetes mellitus or starvation. By using ammonium sulfate, the test can effectively differentiate between normal and abnormal metabolic states.