Pico-molar determination of lurasidone hydrochloride in pharmaceutical formulations using PVC-membrane bulk Miptode

Lurasidone hydrochloride (LRH) is an important medication used for schizophrenia treatment, with minimal side effects of body weight loss, limited sedative capacity and minimal metabolic change; accordingly, its determination is vital, as it is recommended for psychological and memory problems. Molecularly imprinted (MIP) and non-imprinted polymers (NIP) were prepared, and their structures were confirmed by FTIR. MIP and NIP were used as ionophores in bulk membrane optodes (Miptode and Niptode) for LRH determination. Miptode incorporated MIP as an ionophore, tetraphenyl borate as an ion-exchanger, nitrophenyl octyl ether as a plasticizer, and ETH 2439 as a chromoionophore; the response mechanism involved host-guest MIP-LRH complexation via hydrogen bonding, as confirmed by FTIR, followed by deprotonation of the chromoionophore, which caused an absorbance decrease at 675 nm. Compared with Niptode and ion-exchanger-based optodes, Miptode exhibited a very wide concentration range of 10^-11 to 10^-4 M and a very low detection limit of 10 pM. The superior Miptode selectivity was confirmed by the separate solution and mixed solution methods; the mixed solution method exhibited changes in absorbance (% relative error) of 8, 33, and 29% for Miptode, Niptode, and the ion-exchanger-based optode, respectively. The wide linear concentration range, low detection limit, and high selectivity of Miptode were confirmed by the uniform particle size of the MIP at 47 nm and its homogeneous distribution, as observed by SEM and elemental mapping. Miptode was successfully applied to determine LRH in pure solutions, the pharmaceutical formulation Serodopamoun® tablets, and spiked urine samples, with reasonable accuracy (recovery: 98.5-102.3%) and high precision (relative standard deviation <0.81%). MIP is a suitable alternative for enhancing the ionophore library to prepare sensors for any analyte.