Risedronate extraction from artificial urine with using monolithic polymer-based anion exchangers

Bisphosphonates are poorly sorbed from the gastrointestinal tract, therefore, the urinary recovery ratio after oral administration is an important parameter to control. Analysis of bisphosphonates in biological samples causes challenges due to their chemical properties. Their high solubility in water and extensive ionization cause that reported tedious sample extraction methods generally involved a combination of multiple extraction steps. Therefore, competitive solution to the conventional sample preparation techniques was proposed in this work. Aminated poly(styrene-divinylbenzene-vinylbenzyl chloride) monoliths and aminated poly(divinylbenzene-vinylbenzyl chloride) were prepared by in situ polymerization in stainless steel needles. Amination of polymerized monolith was carried out by trimethylamine or pyridine. Several research methods were applied to assess the modification of monolithic materials: Energy dispersive X-ray Spectrometry, scanning electron microscope images and Fourier Transform Infrared Spectroscopy. Artificial urine used as simulated body fluid containing sodium risedronate as standard compound was passed through monolithic in-needle extraction (MINE) device. The amount of analyte in eluate solutions was measured using HPLC system. The effectiveness of complete desorption process was over 95% with using potassium phosphate solution (pH 7.8) as eluent.