Spectrophotometric Determination of Trimipramine in Urine after Its Preconcentration into a Microdroplet Using Homogeneous Liquid-Liquid Extraction

A simple, sensitive and reliable extractive-spectrophotometric method for the determination of trimipramine (TPM) in urine samples was development. In a strong homogeneous acidic medium, trimipramine produced a colored compound which could be extracted into a sedimented microdroplet, in the presence of perfuorooctanoate ion (PFOA–) as a phase separator agent. The concentration of the extracted colored compound in the microdroplet was determined by measuring its absorbance at 390 nm after dilution with methanol. Under the optimal experimental conditions (Concentration of HNO3 = 1.1 mol L–1, Concentration of PFOA– = 7.7 × 10–3 mol L–1, Concentration of THF = 19%), sample solutions containing 0.01 – 7 μg mL–1 of TPM could be analyzed. The maximum concentration factor was 361 (13 mL sample solution produced a 36 μl sedimented liquid phase). The limit of detection of the proposed method was 1.2 ng mL–1. The reproducibility of the proposed method, for the determination of 1.92 μg mL–1 of TPM, on 10 replicated measurements was at most 2.9%. The proposed method was successfully extended to the extraction and determination of trimipramine in pharmaceutical preparations and urine samples. The results showed good agreement to the certified analytical methods.