Multiphase electroextraction as a simple and fast sample preparation alternative for the digital image determination...

Monitoring chemotherapeutic drugs in biological fluids is, in many cases, extremely important for dose adjustment, the maintenance of therapies, and the control of side effects. In this work, a method for determining the doxorubicin in saliva by digital image analysis (DIA) was optimised and validated. Images from a paper point were obtained using a conventional and cheap flatbed scanner at a 600 ppp resolution. The RGB data channels were obtained from the images in a region of 15 × 15 pixels around the sorbent vertex. The paper point was used as sorbent material in sample preparation using a multiphase electroextraction system. Following optimisation using a Doehlert experimental design, the method was able to simultaneously extract 66 samples in 20 min. The high selectivity of the electric field associated with the sorption capacity of the cellulosic material allowed the chemotherapy drug to be pre-concentrated and quantified in a range between 50 and 500 μg L^-1 (R² > 0.98). The method also exhibited adequate parameters (limits of detection and quantification, recovery, and precision) indicating its potential application in the monitoring of doxorubicin and similar drugs in saliva.