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.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide