Urine nitroprusside test

The cyanide nitroprusside test determines the presence of free sulfhydryl or disulfide compounds in urine samples [1, 3,4]. During the first step of the assay, cyanide reduces any disulfides that are present to free sulfhydryl compounds. In the second step, a reddish color reaction results when the free sulfhydryl groups complex with nitroprusside. A positive result is most usually due to cystine in the urine. Familial cystinuria is among the most common aminoacidurias. Disulfides are also excreted in other metabolic disorders such as homo cystinuria and ji-m e reap lol ac la le - cy s lei ne disulfiduria. Both will also produce positive results according to the following reaction RSH + Na2Fe(CN)5NO (sodium nitroprusside) — chromophore + NO. 

M6. Middleton, J. E., A simple, safe nitroprusside test using ketostix reagent strips for detecting cystine and homocystine in urine. J. Clin. Pathol. 23, 90-91 (1970). 

A false positive urine ketone test can also occur with captopril when using the alkaline-nitroprusside test (Ketodiastix), which may affect the monitoring of diabetic control. ... 

Table A,6, Nitroprusside test (urine). This test reacts with sulfur containing acids to form pink to purple color complexes ...

Sodium Nitroprusside Test for Acetoacetic Acid and Acetone (Rothera).—Fill up about 1 in. of a test tube with solid ammonium sulphate. Add 5 ml. of urine, and shake so as to saturate the mixture. Add 2-4 drops of fresh 5 per cent, sodium nitroprusside, and make alkaline with about 10 drops of strong ammonium hydroxide. A deep violet colour develops in a few seconds if the urine contains more than 0-2 per cent, acetoacetic acid, while 0 005 per cent, will give a pink colour in about ten minutes. 

None of the commonly used methods for the detection and determination of ketone bodies in serum or urine reacts with ah three ketone bodies. Gerhardt s ferric chloride test reacts with acetoacetate only. Tests using nitroprusside are at least 10 times more sensitive to acetoacetate than to acetone, and give no reaction at all with P hydroxybutyrate. 

Traditional tests for P-hydroxybutyrate are indirect they require brief boiling of the urine to remove acetone and acetoacetate by evaporation (acetoacetate first breaks down spontaneously to acetone), followed by gentle oxidation of p-hydroxybutyrate to acetoacetate and acetone with peroxide, ferric ions, or dichromate. The acetoacetate thus formed may be detected with Gerhardt s test or one of the procedures using nitroprusside. 

Screening for amphetamines A highly sensitive screening strip for methyl amphetamine in urine may be prepared using the Simon reagent. A silica gel TLC plate is sprayed with equal volumes of 2% sodium nitroprusside and 5% aqueous sodium carbonate solution, and dried for 3 h at 110°C. A strip is cut from the plate to use in the test. 

A test for the detection of ketone bodies in urine based on their reaction with sodium nitroprusside to produce a purple colour. 

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