Enantioselective, Potentiometric Membrane Electrodes Research Articles

Enantioselective, Potentiometric Membrane Electrodes Based on C70 Fullerenes for the Enantioanalysis of S-Clenbuterol in Serum

Two enantioselective, potentiometric membrane electrodes (EPMEs) based on carbon paste impregnated with [5-6] fullerene-C70 (I) and diethyl (1,2-methanofullerene C70)-71-71-dicarboxylate (II) for the enantioanalysis of S-clenbuterol are reported. The electrodes exhibited near-Nernstian (higher than 55.00 mV/decade of concentration) responses only over S-clenbuterol in the following concentration ranges: 10−10 – 10−5 and 10−9 – 10−4 mol/L, for (I) and (II), respectively. The limits of detection were of 10−11 and 10−10 mol/L magnitude order, for EPMEs based on (I) and (II), respectively. The proposed electrodes proved to be successful for the enantioanalysis of S-Clenbuterol as raw material and from serum samples: average recovery of S-Clen in serum samples being higher than 98.40%, with RSD values not exceeding 1.25%.

Quinine, Quinidine and Their Tert-butyl Carbomylated Derivatives as Chiral Selectors in the Enantioselective, Potentiometric Membrane Electrodes Design: Their Application for the Assay of (S) and (R) Enantiomers of 3,5-dinitrobenzoyl Leucine

Quinine, quinidine, tert-butyl carbomylated quinine and tert-butyl carbomylated quinidine are proposed as new chiral selectors in the construction of enantioselective, potentiometric membrane electrodes (EPMEs). A matrix based on carbon paste is used for the design of the electrodes. Electrodes revealed near-Nernstian values for the concentration range of the analytes ((S) and (R)-dinitrobenzoyl leucine (DNB-Leu)) situated in low magnitude order, with low limits of detection (lower than 10−7 mol/L). Quinine and quinide based EPMEs proved to be enantioselective for the (S)-DNB-Leu, while the tert-butyl carbomylated quinine based EPME was enantioselective for (R)-DNB-Leu. The tert-butyl carbamoyl quinidine based electrode was enantioselective only for specific ratios between the (S) and (R)- DNB-Leu enantiomers.

Enantioanalysis of ketoprofen based on its interaction with C60 fullerene and its derivatives

Three enantioselective, potentiometric membrane electrodes (EPMEs) based on C60 fullerene and its derivatives, (1,2-methanofullerene C60)-61-carboxylic acid and tert-butyl(1,2-methanofullerene C60)-61-carboxylate, were designed for the enantioanalysis of ketoprofen. Molecular modelling has been used to investigate the enantioselective binding between the enantiomers of ketoprofen and C60 fullerenes and to prove the mechanism of potential development for the proposed electrodes. The slopes obtained for these electrodes are near-Nernstain with detection limits of 10−8 and 10−7 mol L−1 magnitude order. The proposed electrodes can be reliably used for the enantioanalysis of ketoprofen raw material as well as from its pharmaceutical formulations. Electronic structures as well as molecular interaction have been investigated using Hartree–Fock theory, 3-21G(*) basis set. Stability and feasibility of all the generated structures were supported by their respective energy minima and fundamental frequencies. Molecular modeling calculations were in good agreement with the performances of the proposed electrodes.

Cyclodextrins Based Enantioselective, Potentiometric Membrane Electrodes (EPME) and their Applications for Enantioanalysis of L-Cysteine in Urine

Four enantioselective, potentiometric membrane electrodes based on carbon paste impregnated with α-, β-, 2- hydroxyl-3-trimethylammoniopropyl -β- (as chloride salt) and γ-cyclodextrins are proposed for the enantioanalysis of Lcysteine. The proposed electrodes exhibited near-Nernstian slopes in a wide linear concentration range: 10-10 - 10-3 mol/L, with very low detection limits, near 10-11 mol/L. The surfaces of the electrodes are easily renewable by simply polishing on an alumina paper.

Enantioselective Potentiometric Membrane Electrodes Based on Antibiotics for the Determination of L- and D-Glyceric Acids

Glyceric acid (GA) is a human metabolite existing in L- and D-configurations, which are considered the markers for the diseases L- and D-glyceric aciduria/academia, respectively. Enantioselective, potentiometric membrane electrodes based on carbon paste modified with antibiotics as chiral selectors, vancomycin, and teicoplanin were designed for the assay of L- and D-GA, respectively, in the concentration ranges of 10−9–10−7and 10−4–10−2 moL/L with very low detection limits (1.5 × 10−10 moL/L for L-GA and 1.6 × 10−4 moL/L for D-GA, resp.). The surface of the electrodes can be regenerated simply by polishing in order to obtain a fresh surface ready to be used in a new assay. The proposed electrodes can be successfully applied for the enantioanalysis of L- and D-glyceric acids in serum samples.

Enantioselective Potentiometric Membrane Eectrodes Based on α-, β- and γ-Cyclodextrins as Chiral Selectors for the Assay of S-Deprenyl

Enantioselective, potentiometric membrane electrodes (EPMEs) based on � -, � - and � -cyclodextrins (CDs) as chiral selectors were proposed for the assay of S-deprenyl. The response characteristics proved that the proposed EPMEs could be reliably used in the assay of S-deprenyl. The best slope is exhibited by the EPME based on � -cyclodextrin. The limits of detection are very low: 10 -9 mol L -1 magnitude order for � -cyclodextrin based EPME, and 10 -11 mol L -1 magnitude order for � -, and � -cyclodextrins based EPMEs. The surfaces of the electrodes are stable and easily renewable by polishing on alumina paper.

Enantioanalysis of (-)Butaclamol Using Vancomycin and Teicoplanin as Chiral Selectors

Butaclamol is an antipsychotic drug used in the treatment of schizophrenia. The macrocyclic antibiotics, vancomycin and teicoplanin, are proposed as chiral selectors for the design of the enantioselective, potentiometric membrane electrodes (EPMEs) for the assay of (-)butaclamol. The slopes of the electrodes are near-Nernstian for the assay of (-) butaclamol with linear concentration ranges between 10(-10) and 10(-7) mol/L and between 10(-9) and 10(-7) mol/L for vancomycin and teicoplanin based EPMEs. Limits of detections varied. The electrodes were used reliably for the enantioanalysis of (-) butaclamol in serum samples.

Enantioanalysis of S-Ketoprofen Using Enantioselective, Potentiometric Membrane Electrodes

Maltodextrins with different dextrose equivalent (DE) values (maltodextrin I: DE 4.0–7.0; maltodextrin II: DE 13.0–17.0; maltodextrin III: DE 16.5–19.5) were used for the design of three enantioselective, potentiometric membrane electrodes (EPMEs) for the assay of S-ketoprofen. The linear concentration ranges for the proposed electrodes were 10−10 to 10−8, 10−9 to 10−5, and 10−10 to 10−7 mol/L, with slopes of 58.0, 58.67, and 58.93 mV/decades of concentration and limits of detection of 1.49 × 10−8, 2.43 × 10−8, and 4.19 × 10−11 mol/L for EPMEs based on maltodextrin I, II, and III, respectively. The EPMEs showed high reliability and effectiveness for the enantioanalysis of S-ketoprofen raw material and its pharmaceutical formulations.

Enantioselective, Potentiometric Memberane Electrodes Based on Different Cyclodextrins as Chiral Selectors for the Assay of S‐Flurbiprofen

AbstractFour enantioselective, potentiometric membrane electrodes (EPMEs) based on carbon paste impregnated with α‐, β‐, 2‐hydroxyl‐3‐trimethylammoniopropyl‐β‐(as chloride salt) and γ‐cyclodextrins, were proposed as a chiral selectors for assay of S‐flurbiprofen raw materials and in its pharmaceutical formulation Froben 100 tablets. The best response was obtained when β‐cyclodextrin was used for the electrode design. The four EPMEs showed very low detection limits (of 10−8 to 10−9 mol/L magnitude orders). The surfaces of the electrodes are easily renewable by simply polishing on an alumina paper.

Enantioselective potentiometric membrane electrodes based on C 60 fullerene and its derivatives for the assay of l-Histidine

Novel enantioselective, potentiometric membrane electrodes (EPMEs) based on carbon paste impregnated with C 60 fullerene (I), (1,2-methanofullerene C60)-61-carboxylic acid (II), diethyl(1,2-methanofullerene C60)-61-61-dicarboxylate (III) and tert-butyl(1,2-methanofullerene C60)-61-carboxylic acid (IV) are reported. Response characteristics showed that the proposed electrodes could be reliably used in the assay of l-Histidine ( l-His), with the best enantioselectivity and time-stability exhibited by fullerene derivatives. The surfaces of the electrodes are stable and easily renewable by simply polishing on an alumina paper. All proposed electrodes proved to be successful for the determination of the enantiopurity of histidine as raw material and of its pharmaceutical formulation.

Utilization of Maltodextrin‐Based Enantioselective, Potentiometric Membrane Electrodes for the Enantioselective Assay of S‐Flurbiprofen

Three enantioselective, potentiometric membrane electrodes (EPMEs) based on carbon paste impregnated with different maltodextrins [dextrose equivalent (DE) (DE 4.0–7.0 (I), 13–17 (II), 16.5–19.5 (III)], were proposed as chiral selectors for the assay of S‐flurbiprofen raw materials and from its pharmaceutical formulation, Froben 100® tablets. The best response and enantioselectivity were obtained when maltodextrin with lower DE was used for the electrode design. The three EPMEs showed very low detection limits. The surfaces of the electrodes are easily renewable by simply polishing on an alumina paper.

Enantioselective assay of S(+)-ibuprofen using enantioselective, potentiometric membrane electrodes based on maltodextrins

Three enantioselective, potentiometric membrane electrodes (EPMEs) based on maltodextrins with different values of dextrose equivalence(DE) (maltodextrin I: DE 4.0–7.0; maltodextrin II: DE 13.0–17.0; maltodextrin III: DE 16.5–19.5) were proposed for the assay of S-ibuprofen. The linear concentration ranges for the proposed EPMEs were 10 −10 to 10 −3, 10 −8 to 10 −3 and 10 −10 to 10 −3 mol l −1 for electrodes based on maltodextrin I, II and III, respectively. The slopes of the electrodes were 59.0, 58.4 and 55.6 mV/decade of concentration for maltodextrin I, II and III based EPMEs, respectively, with detection limits of 5.5 × 10 −11, 8.0 × 10 −9 and 4.1 × 10 −12 mol l −1 for the electrodes based on maltodextrin I, II and III, respectively. A high reliability was obtained when the electrodes were used for the assay of S-ibuprofen raw material and its pharmaceutical formulations Myprodol capsules and Nurofen tablets. The surfaces of the electrodes are stable and easily renewable by polishing on alumina paper.

Determination of L‐Vesamicol in Serum Samples Using Enantioselective, Potentiometric Membrane Electrodes Based on Antibiotics

Enantioselective, potentiometric membrane electrodes (EPMEs) based on antibiotics are proposed for the enantioanalysis of L‐vesamicol. A carbon paste was modified with antibiotics (vancomycin, teicoplanin, and teicoplanin modified with acetonitrile), as chiral selectors. The EPMEs based on antibiotics were reliably used for enantiopurity tests of L‐vesamicol using the direct potentiometric technique. The following linear concentration ranges: 1.0×10−6–1.0×10−4, 1.0×10−6–1×10−3 and 1×10−7−1×10−2 mol/L; and detection limits: 1.1×10−7, 9.6×10−8, and 3.6×10−8 mol/L were determine for vancomycin, teicoplanin, and teicoplanin modified with acetonitrile–based EPMEs, respectively. The proposed EPMEs were applied for the enantioanalysis of L‐vesamicol in urine samples.

Enantioselective, Potentiometric Membrane Electrodes Based on Cyclodextrins for the Assay of L‐ and D‐2‐Hydroxyglutaric Acid

Enantioselective, potentiometric membrane electrodes (EPMEs) based on immobilization of β‐, γ‐cyclodextrin (CD) or 2‐hydroxy‐3‐trimethylammoniopropyl‐β‐cyclodextrin (as chloride salt) (β‐CD‐derivative) in carbon paste have been designed. The β‐CD and β‐CD‐derivative‐based electrodes were applied in the 10−8–10−6 and 10−7–10−5 mol/L concentration ranges for the determination of L‐2‐hydroxyglutaric acid (L‐2‐HGA), whereas γ‐CD‐based electrode was applied for the determination of D‐2‐hydroxyglutaric acid (D‐2‐HGA) in the concentration range 10−6–10−4 mol/L. The β‐CD‐based EPME showed the lowest detection limit (1×10−9 mol/L). The enantioselectivity and selectivity of the proposed electrodes for the assay of L‐2‐HGA and D‐2‐HGA, respectively, were determined over D‐2‐HGA/L‐2‐HGA, creatine, and creatinine. The proposed EPMEs can be applied for the enantioanalysis of 2‐hydroxyglutaric acid in urine samples.

Enantioanalysis of glyceric acid using enantioselective, potentiometric membrane electrodes: applications for the diagnosis of PH II and d-glyceric acidemia/acidurias

d- and l-glyceric acids are human metabolites responsible for two different diseases. Excess excretion of d-GA causes d-glyceric academia/acidurias, while excess excretion of l-GA causes hyperoxaluria type 2, PH II. Enantioselective, potentiometric membrane electrodes (EPMEs) based on maltodextrins I (dextrose equivalence (DE) 4.0–7.0), II (DE 13.0–17.0) and III (DE 16.5–19.5) as chiral selectors are proposed for the determination of l-glyceric (EPMEs based on maltodextrins I and III) and d-glyceric (EPME based on maltodextrin II) acid ( l- and d-GA). EPMEs based on maltodextrins I and III can be reliably used for the analyses of l-GA using direct potentiometric method, in the concentration range of 10 −8 to 10 −6 and 10 −6 to 10 −3 mol/L, respectively, with very low detection limits (1.19 × 10 −9 and 1.0 × 10 −7 mol/L, respectively). The EPME based on maltodextrin II was successfully used for the enantioanalysis of d-GA in the 10 −5 to 10 −3 mol/L concentration range with detection limit of 1 × 10 −6 mol/L. The enantioselectivity of EPMEs was determined over l-glyceric acid (or d-glyceric acid), and their selectivity over creatine, creatinine and some inorganic cations such as Na +, K + and Ca 2+. Simply polishing to obtain a fresh surface ready to be used in a new measurement can regenerate the surface of the electrodes.

Determination of d-2-hydroxyglutaric acid in urine samples using enantioselective, potentiometric membrane electrodes based on antibiotics

Enantioselective, potentiometric membrane electrodes (EPMEs) based on carbon paste are constructed. The carbon paste is modified with antibiotics: vancomycin, teicoplanin, and teicoplanin modified with acetonitrile. The proposed electrodes can be used reliably for enantiopurity tests of d-2-hydroxyglutaric acid using direct potentiometric method of analysis. The linear concentration ranges recorded for EPMEs are 10 −7 to 10 −3, 10 −7 to 10 −2 and 10 −6 to 10 −2 mol/L with detection limits of 1.00 × 10 −8, 1.00 × 10 −8, 1.00 × 10 −7 mol/L for the vancomycin, teicoplanin and teicoplanin modified with acetonitrile based EPME, respectively. The selectivity was determined over l-2-hydroxyglutaric acid, creatine, creatinine and some inorganic cations. The proposed EPMEs were applied for the assay of d-2-hydroxyglutaric acid in urine samples. The duration of one analysis is 10 min, including the calibration of the instrument and the determination of the amount of d-2-hydroxyglutaric acid in the urine sample.

Determination of baclofen enantiomers in pharmaceutical formulations using maltodextrin-based enantioselective, potentiometric membrane electrodes

Two enantioselective, potentiometric membrane electrodes (EPMEs) based on maltodextrins with different value of dextrose equivalent (DE) (maltodextrin I: DE 4.0-7.0; maltodextrin II: DE 16.5-19.5) were proposed for the assay of baclofen enantiomers in baclofen raw materials and from its pharmaceutical formulation, Norton-Baclofen ® tablets. The slopes of the electrode function of the proposed electrodes were 55.0 mV/p S-baclofen for maltodextrin I-based electrode and 59.0 mV/p R-baclofen for maltodextrin II-based electrode and the detection limits were 1.34 × 10 –6 mol l –1 ( S-baclofen) and 2.52 × 10 –10 mol l –1 ( R-baclofen), respectively. The surfaces of the electrodes are stable and easily renewable by simply polishing on alumina paper.

Enantioanalysis of l-2-hydroxyglutaric acid in urine samples using enantioselective, potentiometric membrane electrodes based on maltodextrins

Quantitative assay of l-2-hydroxyglutaric acid ( l-2-HGA) is important for the diagnosis of l-2-hydroxyglutaric aciduria. Three enantioselective, potentiometric membrane electrodes (EPMEs) based on maltodextrins with different dextrose equivalent (DE) (DE: 4.0–7.0 (I), 13.0–17.0 (II), 16.5–19.5 (III)), were designed for the enantioanalysis of l-2-HGA. The enantioselective, potentiometric membrane electrodes can be used reliably for enantiopurity assay of l-2-HGA using the direct potentiometric method in the ranges of 10 −9–10 −5, 10 −6–10 −3 and 10 −8–10 −5 mol L −1 for the enantioselective, potentiometric membrane electrodes based on maltodextrins I, II and III, respectively, with very low detection limits. A high reliability was obtained when the electrodes were used for the assay of l-2-HGA in urine samples.

Macrocyclic antibiotics as chiral selectors in the design of enantioselective, potentiometric membrane electrodes for the determination of l- and d-enantiomers of methotrexate

Three enantioselective, potentiometric membrane electrodes (EPMEs) based on macrocyclic glycopeptide antibiotics—vancomycin and teicoplanin (modified or not with acetonitrile)—were proposed for the determination of l- and d-enantiomers of methotrexate (Mtx). The linear concentration ranges for the proposed enantioselective membrane electrodes were between 10 −6 and 10 −3 mol l −1 for l- and d- methotrexate. The slopes of the electrodes were 58.00 mV/p l-Mtx for vancomycin-based electrode; 57.60 mV/p d-Mtx for teicoplanin-based electrode and 55.40 mV/p d-Mtx for teicoplanin modified with acetonitrile-based electrode. The detection limits of the proposed electrodes were of 10 −8 mol l −1 magnitude order. The surfaces of the electrodes are stable and easily renewable by polishing on alumina paper. All proposed electrodes proved to be successful for the determination of the enantiopurity of Mtx as raw material and of its pharmaceutical formulations (tablets and injections).

Enantioselective, potentiometric membrane electrodes based on maltodextrins.: Their applications for the determination of l-proline

The construction of enantioselective, potentiometric membrane electrodes (EPMEs) impregnated with the following maltodextrins having dextrose equivalence (DE) 4.0–7.0 (I), 13.0–17.0 (II) and 16.5–19.5 (III)—as chiral selectors is described. The response characteristics showed that the proposed electrodes could be reliably utilized in the assay of l-proline ( l-Pro) as raw material, with the best enantioselectivity and time-stability exhibited when the EPME based on malodextrin I was used. The three EPMEs showed very low detection limits (of 10 −9 mol/l magnitude order). The surfaces of the electrodes are easily renewable by simply polishing on an alumina paper.