37,40-bis-(diethoxy-thiophosphoryl)oxy-5,11,17, 23,29,35-hexakis(1,1-dimethyl-ethyl)-calix[6]arene-8,39,41,42-tetrol; 37,38,39,40,41-pentakis-(diethoxythiophosphoryl)-oxy-5,11,17,23,29,35-hexakis (1,1-dimethylethyl)-calix[6]-arene-42-ol; and 37-(diethoxythiophosphoryl)oxy-5,11,17,23,29,35-hexakis-(1,1dimethylethyl)-calix[6]arene-38,39,40, 41,42-pentol were introduced as neutral ionophores for atropine-selective electrodes. Practical Nernstian responses were found (54.3, 49.1, and 50.8 mV/decade) for polyvinyl chloride membrane electrodes incorporating these compounds. They exhibited practical linear ranges of 1.9 10^-6-7.9 10^-3,7.9 10^-6-7.9 10^-3, and 6.3 10^-6-7.9 10^-3 M, respectively. The optimum pH range was 2.58.5. The selectivity coefficient values were estimated and interpreted. The electrode performance was correlated to the calixarene structure. Then, the electrode was applied to an actual analysis of pharmaceutical atropine preparations. The recovery values of 18.7 g/mL-5.5193 mg/mL atropine sulfate were 97.599.1%. The corresponding relative standard deviation values ranged between 0.39-0.72% for 5 determinations. The first electrode was applied successfully for analyzing atropine sulfate in injection solution and eye drops.

А grаdiеnt HPLC mеthоd was dеvеlоpеd аnd vаlidаtеd fоr rаpid simultаnеоus sеpаrаtiоn аnd dеtеrminаtiоn оf the following eight drugs оf sаrtаn аnd stаtin clаssеs in thеir purе аnd dоsаgе fоrms within 15 minutes: irbеsаrtаn (IRB), lоsаrtаn (LОS), vаlsаrtаn (VАL), оlmеsаrtаn (ОLM), rоsuvаstаtin (RОS), аtоrvаstаtin (АTR), lоvаstаtin (LОV), аnd simvаstаtin (SIM). Sеpаrаtiоn wаs cаrriеd оut оn а Kinеtеx C₁₈ 100А cоlumn (2.60 m, 4.60 mm × 100 mm) using а grаdiаnt binаrу mоbilе phаsе оf 0.05M pоtаssium dihуdrоgеn phоsphаtе buffеr (pH 3.50 аdjustеd bу оrthо-phоsphоric аcid) аnd аcеtоnitrilе аt rооm tеmpеrаturе. Thе flоw rаtе wаs 1.00 mL/min аnd mаximum аbsоrptiоn wаs mеаsurеd using a DАD dеtеctоr аt 280 nm. Thе rеtеntiоn timеs оf IRB, LОS, RОS, VАL, АTR, LОV, ОLM, аnd SIM wеrе rеcоrdеd tо bе 4.72, 5.32, 6.06, 7.19, 7.96, 9.30, 11.91, аnd 14.66 minutеs, rеspеctivеlу. Limits оf dеtеctiоn wеrе rеpоrtеd tо bе 2.01, 1.32, 1.10, 0.76, 0.21, 1.50, 0.38, аnd 0.55 mM fоr thе sаmе sеquеncе оf drugs, rеspеctivеlу, shоwing а high dеgrее оf mеthоd sеnsitivitу. Thе mеthоd wаs thеn vаlidаtеd аccоrding tо the intеrnаtiоnаl cоnfеrеncе оf hаrmоnizаtiоn (ICH) guidеlinеs fоr thе dеtеrminаtiоn оf thе drugs in thеir dоsаgе fоrms with highlу prеcisе rеcоvеriеs. Аlsо, a stаtisticаl cоmpаrisоn with rеfеrеncе mеthоds wаs pеrfоrmеd shоwing nо significаnt diffеrеncеs bеtwееn thе prоpоsеd mеthоd аnd rеpоrtеd оnеs in tеrms оf prеcisiоn аnd аccurаcу.

A pH electrode for the selective determination of H+ was introduced. Both phosphorated calix[6]arene and a N,N'-bisethoxycarbonyl-1,10-diaza-4,7,13,16-tetraoxacyclo-octadecane (DZCE) were used as new H+-ionophores. The calibration graphs of the obtained electrodes exhibits satisfactory Nernstian slopes. The electrodes were compared to blank membranes (without any ionophoric substances) for the first time. Selectivity coefficients of the studied electrodes towards several inorganic cations were calculated. The relative selectivity coefficient (RSC) was applied for evaluating the selectivity properties of H+-electrode using a mathematical equation. The electrodes were applied for the determination of different inorganic and organic acids.

TFPB was introduced as a charged ionophore for atropine selective electrodes. Typical Nernstian responses were found (57.78, 58.95 and 58.41 mV/decade) for PVC-membrane electrodes incorporating NPOE, DOS, and DDP as plasticizers. They exhibited practical linear ranges of 9.1 × 10^-3 - 10^-6, 9.1 × 10^-3 - 10^-6 and 9.1 × 10^-3 - 10^-7 M, respectively. It works in the sub-micro scale of atropine concentrations. The optimum pH-range was 3.18 - 8.97. The selectivity coefficient values were estimated for different organic and inorganic cations. They were interpreted by using the “Relative Selectivity Concept”, which was introduced for the first time. The new concept was applied for comparing the selectivity properties of previously reported electrodes. The effect of the presence of ephedrine, caffeine, glucose, Na⁺, Ca²⁺, and Mg²⁺ on the calibration graphs of the electrodes was studied.

This chapter included an explanation of the role of cyclodextrin as an ionophore for the preparation of voltammetric and potentiometric sensors for different compounds. There was a surveying of the different recorded cyclodextrin-based sensors for drug, organic, or inorganic cations. It also explained the performance characteristics for the first reported sensor for nickel based on β-cyclodextrin as an example.