Optimizing carry-over in automated dissolution system dissoBOT for paracetamol and diclofenac sodium analysis

In this work, an automated dissolution system (dissoBOT) was used for dissolution testing for the first time. Carry-over (CO) of the dissoBOT was determined for paracetamol (PA) and diclofenac sodium (DS), which are active pharmaceutical ingredients (APIs). Initially, partial method validation of the UV-VIS spectrophotometry method for PA and DS determination was performed by defining the limit of detection (LOD), the limit of quantification (LOQ), linear concentration range, accuracy, and precision. The LODs and LOQs were less than 0.01 mg/L for both APIs. The determined linear concentration ranges were from 1.00 mg/L to 30.00 mg/L for PA and from 0.50 mg/L to 3.50 mg/L for DS (the square of the correlation coefficient was greater than 0.9990, and the quality coefficient was less than 1.00 % for both APIs). The accuracy of the method was evaluated by calculating the recovery (Re) of the solutions of standards with known concentrations. The method for both APIs was deemed to be accurate (the average Re for PA and DS were 99.81 % and 101.43 %, respectively). Precision was evaluated by calculating the relative standard deviation (RSD). The method for PA and DS was deemed to be precise, as the RSD value for PA was 0.13 %, and for DS was 0.38 %. The volume (V) of the washing medium in both cleaning cycles performed by the dissoBOT system, as well as the medium dispensing V, were established, where the medium dispensing V was in accordance with the United States Pharmacopeia requirements. The CO of the dissoBOT system, using tap water as the washing medium, was determined to be less than 1.00 % for both APIs. The CO values for one cleaning cycle of the sampling station with a V of 2 mL was in the range of 1.24–1.54 %, for V of 5 mL was in the range of 0.78–0.93 %, and for V of 10 mL was in the range of 0.27–0.36 %. In addition, the CO of the dissoBOT, when employing two cleaning cycles of the sampling station (each V of 10 mL) was reduced (CO <0.20 %). Finally, the dissoBOT was successfully employed for the dissolution PA and DS tables.