Theoretical and chemometrical analysis of the retention mechanisms of selected drugs in hydrophilic interaction liquid chromatography

[M. М. Jovanović]

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Farmaceutska hemija - Analitika lekova / Pharmaceutical chemistry - Drug analysis

Retenciono ponašanje i retencioni mehanizmi lekova različitih kiselo–baznih osobina na polarnim i umereno polarnim stacionarnim fazama detaljno su ispitani pomoću teorijskih i eksperimentalnih modela u tečnoj hromatografiji hidrofilnih interakcija (eng. Hydrophilic Interaction Liquid Chromatography – HILIC). Teorijskim modelima prevashodno je omogućeno razjašnjavanje retencionih mehanizama u ispitivanim HILIC sistemima, dok su eksperimentalni modeli bili od značaja u analizi retencionog ponašanja u zavisnosti od većeg broja ispitivanih faktora i kvantifikaciji faktorskih uticaja, kao i njihovih interakcija. Literaturni podaci pokazali su da je do sada najveći broj analiza u HILIC sistemima izveden u silika kolonama, pri čemu su najčešće bile razdvajane bazne supstance zbog svog velikog afiniteta prema ovom tipu stacionarnih faza. U ovom delu disertacije, primenom hemometrijskog pristupa, ispitano je retenciono ponašanje kiselih i amfoternih farmaceutski aktivnih supstanci na primeru model smeše β–laktamskih antibiotika u silika koloni. Kvantifikacija faktorskih uticaja omogućena je građenjem eksperimentalnih modela u formi polinoma drugog reda, a faktorske interakcije grafički su prikazane u vidu trodimenzionih površina odgovora. Verifikacija dobijenih modela urađena je poređenjem simuliranih i eksperimentalno dobijenih hromatograma u proizvoljno odabranim tačkama eksperimentalnog prostora. Separacioni mehanizam u HILIC sistemima izuzetno je složen i do sada nedovoljno proučen. Smatra se da mogu biti uključeni procesi raspodele, adsorpcije i/ili jonske izmene, a da relativan udeo svakog od njih zavisi od tri grupe faktora: strukturnih karakteristika analita, sastava mobilne faze i vrste kolone. Zato su u nastavku istraživanja ispitani retencioni mehanizmi i retenciono ponašanje baznih analita na primeru model smeše odabranih farmaceutski aktivnih supstanci u dve silika, dve cijano i jednoj diolnoj stacionarnoj fazi korišćenjem teorijskih i eksperimentalnih retencionih modela. Fitovanjem retencionih podataka u katjonsko–izmenjivačke retencione modele kvantifikovan je doprinos procesa katjonske izmene u ukupnom HILIC retencionom mehanizmu ovih analita, dok je udeo procesa raspodele i adsorpcije ispitan na osnovu kreiranih particionih i adsorpcionih retencionih modela...

The assessment of the retention behavior and retention mechanisms of drugs with different acido–basic properties on various polar and moderately polar stationary phases was carried out with the aid of theoretical and empirical models in hydrophilic interaction liquid chromatography (HILIC). Theoretical models primarily enabled the elucidation of the retention mechanisms in the examined HILIC systems, whereas empirical models were useful in the analysis of the retention behavior as a function of several examined factors and in the quantification of factor influences, as well as their interactions. Literature survey has shown that the greatest number of separations in HILIC mode was performed on bare silica columns. Since basic analytes have high affinity towards this type of stationary phases, they were most commonly analyzed on bare silica columns. In this part of dissertation the retention behavior of acidic and amphoteric analytes on the example of a model mixture of β–lactam antibiotics on bare silica column utilizing chemometric approach was investigated. Quantification of factor influences was enabled through the creation of empirical models in the form of second–order polynomial and factor interactions were graphically represented as 3D response surface plots. Verification of the created models was conducted by comparing simulated and experimentally obtained chromatograms at random points of experimental space. Separation mechanism in HILIC systems is complex and insufficiently investigated so far. It is believed that it involves partition, adsorption and/or ion–exchange processes, and that the dominance of each process depends on three groups of factors: structural characteristics of the analytes, mobile phase composition and column type. Thus, further on, the retention mechanisms and retention behavior of basic analytes on the example of a model mixture of selected basic drugs on two bare silica, two cyano and one diol stationary phase using theoretical and empirical retention models were assessed. By fitting the retention data in cation–exchange models the involvement of cation–exchange process in the overall HILIC retention mechanism was quantified...

tečna hromatografija hidrofilnih interakcija, retenciono ponašanje, retencioni mehanizmi, teorijski modeli, eksperimentalni modeli, hemometrija, eksperimentalni dizajn, optimizacija

hydrophilic interaction liquid chromatography, retention behavior, retention mechanisms, theoretical models, empirical models, chemometrics, experimental design, optimization

615.074:543.544:001.891.54(043.3)

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