Solidified single drop microextraction of chlorpromazine based on ion pair formation with methyl orange followed by spectrophotometric determination

Chlorpromazine (CPZ) is an antipsychotic medication which is primarily used to treat psychotic disorders such as schizophrenia. Other applications include treatment of bipolar disorder, attention deficit hyperactivity disorder, nausea and vomiting, anxiety before surgery, and hiccups that do not improve following other measures [1]. This paper presents an efficient and visual measurement system for quantitative sensing of CPZ. The method is based on ion pair formation of CPZ with methyl orange and extraction into solidified single drop of undecanol followed by spectrophotometric detection. The extracted methyl orange into the solidified single drop of undecanol shows a very week absorption peak at a maximum wavelength of 429 nm. Upon the addition of the analyte, CPZ, due to the formation of ion pair, intensity of absorption peak is increased. The difference in absorption intensity between the sample containing CPZ and the blank solution was taken as analytical signal in this method. The effect of experimental parameters such as pH, centrifugation time, type and volume of solvent, type and volume of dispersant, amount of dye used, tolerated volume, shaking time, salt effect and some potential chemical interference on the preconcentration process was studied. The increased in the absorption intensity of CPZ-methyl orange was linear with the concentration of CPZ in the range of 15-350 ng mL-1. The detection limit was 4.35 ng mL-1 and the relative standard deviations for 8 replicate measurements inter day and intraday of 200 ng mL-1 of chlorpromazine were 1.45 and 4.05 %, respectively. The developed method was successfully employed to the determination of CPZ in blood serum, blood plasma and whole-mouth saliva samples with satisfactory results.