Determination of antipyrine in saliva using the dispersive liquid–liquid microextraction based on a stepwise injection system

• A novel approach: stepwise injection analysis—dispersive liquid–liquid microextraction (SWIA-DLLME).
• A fully automated method for determination of antipyrine in saliva.
• The method allows determining of microsomal oxidase oxidation phenotype of patients.

A fully automated stepwise injection spectrophotometric method for determination of antipyrine in saliva (agent for non-invasive assessment of the activity of the drug metabolizing system in hepatocytes) has been developed. The method is based on the antipyrine derivatization by nitrite-ion dispersive liquid–liquid microextraction (DLLME) of formed 4-nitrosoantipyrine with subsequent UV–vis spectrophotometric detection. Under optimal experimental conditions (0.5 М sulfuric acid, 6×10−3 М sodium nitrite, time 6 min) the absorbance of the colored extract at the 345 nm obeys Beer׳s law in the range of 3–200 μM of antipyrine in saliva. The LOD, calculated from a blank test, based on 3σ, found to be 1 μM. The relative standard deviation for the determination of 50 μM antipyrine was 4.5% (n=10). The proposed method was successfully applied to the determination of antipyrine in saliva and the analytical results agreed fairly well with the results obtained by reference HPLC method.

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