nitroprussiditestillä

The nitroprusside test, also known as the nitroprusside reaction or cyanide test, is a simple chemical assay used primarily to detect the presence of sulfide ions (S²⁻) in a sample. The test is widely employed in clinical, environmental, and industrial settings due to its sensitivity and ease of use.

The reaction involves the addition of sodium nitroprusside (Na₂[Fe(CN)₅NO]) to a sample suspected of containing sulfides. When sulfide ions are present, they react with the nitroprusside complex, forming a deep purple-colored compound known as sodium pentacyanonitrosylferrate(II) (Na₄[Fe(CN)₅NOS]). The intensity of the purple coloration correlates with the concentration of sulfide ions in the sample, allowing for qualitative or semi-quantitative analysis.

In clinical chemistry, the nitroprusside test is often used to detect ketones in urine, particularly acetone, as a marker for conditions such as diabetic ketoacidosis. This application relies on the reaction between nitroprusside and acetoacetate, a ketone body, in the presence of alkaline conditions, producing a purple color. The test is commonly referred to as the nitroprusside test for ketones or the Rothera’s test when applied in this context.

The test is straightforward to perform, requiring only a few drops of the reagent solution to be mixed with the sample. However, it is important to note that false positives or negatives can occur depending on the sample matrix and interfering substances, such as certain drugs or high concentrations of ascorbic acid. Proper calibration and control tests are recommended for accurate results.

While the nitroprusside test is valuable for its simplicity and speed, it is generally not as precise as instrumental methods like chromatography or spectroscopy for quantitative analysis. Its primary strength lies in its utility as a rapid screening tool for the presence of specific compounds, particularly sulfides and ketones.