New spectrophotometric microdetermination of carbapenem antibiotics derivatives in pharmaceutical formulations

AbstractA new sensitive spectrophotometric method was developed to determine three carbapenem antibiotics: imipenem, meropenem and ertapenem. The proposed method was based on the formation of the coloured tris(o-phenanthroline)-iron(II) complex (ferroin) [Phen] or Fe (II)-2,2″-bipyridyl complex [Bip] in the reaction of the tested drugs with the corresponding iron (III)-complexes in an acetate pH 4 buffer. The formed coloured complexes showed maximum absorbance at 510 and 520nm for [Phen] and [Bip], respectively. The reaction conditions, including the pH, reagent concentration, reaction time, temperature and stability of the formed coloured species, were optimized to achieve the highest sensitivity. Linear calibration curves were obtained in the concentration ranges from 0.2 to 10, 0.5 to 10 and 0.5 to 10μgmL−1 for the aforementioned drugs in the same order. The developed method was successfully applied to determine the investigated carbapenems in their pharmaceutical formulations with average recoveries of 100.8, 99.8 and 99.4% for the Phen method and 98.9, 101.7 and 100.6% for the Bip method for imipenem, meropenem and ertapenem, respectively. A statistical comparison of the results with the reference method showed good concurrence and indicated no significant difference in accuracy or precision

Ionophore-based potentiometric sensors for drug analysis

The construction, evaluation and analytical application of ionophore-based sensors for potentiometric determination of hexoprenaline sulphate (Hx) or biperiden hydrochloride (BP) are reported. Electrode matrices compositions are optimized on the basis of the nature and content of sensing ionophore, ionic sites and plasticizers. Sensors incroporated with β-cyclodextrins (β-CDs), sodium tetrakis (4-fluorophenyl) borate (NaTFPB) and 2-fluorophenyl 2-nitrophenyl ether (f-NPE), showed fast and stable potentiometric responses with mean Nernstian compliance of 59.0 ± 1.0 and 56.8 ± 1.4 mV·decade-1 for Hx and BP, respectively in the concentration ranges 1×10–5–1×10–2 mol·L–1 for Hx and 1×10–5–1×10–2 mol·L–1 for BP. Incorporation of β-CD as molecular recognition element improved the electrode sensitivity and¨selectivity due to encapsulation of the drug molecule into β-CD cavity (host-guest interaction). The electrodes were fully characterized in terms of composition, usable pH range, life span and response time. The developed electrodes have been successfully applied for the potentiometric determination of the cited drugs in pharmaceutical formulations. Comparison of the obtained results with those provided by reference methods revealed adequate accuracy for control assay

Cyclodextrin-based potentiometric sensors for Metformin

-Cyclodextrins ( -CDs) based polyvinylchloride (PVC) electrodes were fabricated and applied for potentiometric determination of Metformin (Mf). Matrix composition optimization was done referring the effect of type and content of -CDs, anionic sites and plasticizer. Electrodes incorporated with 2-hydroxypropyl- -CD as sensing ionophore, sodium tetrakis (4-florophenyl) borate (NaTFPB) as anionic site and o-nitrophenyloctyl ether (o-NPOE) as electrode plasticizer showed the best electroanalytical performances. The fabricated electrodes worked satisfactorily in the concentration range from 10-6 to 10-2 mol L-1 with detection limit reaching 7×10-6 mol L-1 and fast response time of 8 s. The developed sensors possessed improved selectivity and have been successfully applied for the potentiometric determination of Mf in pharmaceutical formulation. Comparison of the obtained results with those provided by reference method revealed adequate accuracy for control assay

Elektrochemická charakterizace nových sítotiskových uhlíkových pastovitých elektrod pro voltametrické měření

This work is focused on the homemade screen-printed carbon paste electrode containing basically graphite powder (or glassy carbon powder), poly(vinylbchloride) (PVC) and paraffin oil. It compares the electrochemical properties of conventional carbon-based electrodes and prepared screen-printed carbon paste electrodes towards [Fe(CN)(6)](3-)/[Fe(CN)(6)](4-) and quinone/hydroquinone redox couples. Significant attention is paid to the development of the corresponding carbon inks, printing and the surface characterisation of the resulting electrodes by the scanning electron microscopy. An optimization consisted of the selection of the organic solvent, the optimal content of the used polymer with the chosen paste binder, appropriate isolation of electric contact, etc. Very similar properties of the prepared screen-printed electrodes, containing only corresponding carbon powder and 3 % PVC, with their conventional carbon paste electrode and glassy carbon-based electrodes, were observed during their characterisation. Screen-printed electrodes, with the pasting liquid usually provided satisfactory analytical data. Moreover, they can be used in the flow injection analysis and could undoubtedly replace the carbon paste grooved electrodes. It can be assumed that certain progress in the development of electrode materials was achieved by this research.Tato práce se zaměřuje na ručně vyráběné tištěné pastové elektrody obsahující v podstatě grafitový prášek (sklovitý uhlíkový prášek), polyvinylchlorid (PVC) a parafínový olej. V článku se porovnávají konvenční pastové elektrody s těmi v tištěné podobě na základě měření rodox párů jako [Fe(CN)(6)](3-)/[Fe(CN)(6)](4-) a chinon/hydrochinon. Významná pozornost je věnována samotné přípravě vodivých inkoustů, tištění a charakterizaci povrchu pomocí elektronové mikroskopie. Optimalzace spočívala ve vybrání správného organického rozpouštědla, polymeru, pastovací kapaliny, izolace elektrických kontaktů atd. Velmi podobné vlastnosti připravených sítotiskových elektrod, obsahujících pouze odpovídající uhlíkový prášek a 3% PVC, s konvenční uhlíkovou pastovou elektrodou byly pozorovány během jejich charakterizace. Sítotiskové elektrody s pastovací kapalinou obvykle poskytují uspokojivé analytické vlastnosti. Kromě toho mohou být použity v průtokové injekční analýze a mohly by nepochybně nahradit žlábkové elektrody obsahující uhlíkovou pastu. Závěrem lze předpokládat, že určitý pokrok ve vývoji elektrodových materiálů byl dosažen tímto výzkumem

Electrochemical characterisation of novel screen-printed carbon paste electrodes for voltammetric measurements

This work is focused on the homemade screen-printed carbon paste electrode containing basically graphite powder (or glassy carbon powder), poly(vinylbchloride) (PVC) and paraffin oil. It compares the electrochemical properties of conventional carbon-based electrodes and prepared screen-printed carbon paste electrodes towards [Fe(CN)6]3-/[Fe(CN)6]4- and quinone/hydroquinone redox couples. Significant attention is paid to the development of the corresponding carbon inks, printing and the surface characterisation of the resulting electrodes by the scanning electron microscopy. An optimization consisted of the selection of the organic solvent, the optimal content of the used polymer with the chosen paste binder, appropriate isolation of electric contact, etc. Very similar properties of the prepared screen-printed electrodes, containing only corresponding carbon powder and 3 % PVC, with their conventional carbon paste electrode and glassy carbon-based electrodes, were observed during their characterisation. Screen-printed electrodes, with the pasting liquid usually provided satisfactory analytical data. Moreover, they can be used in the flow injection analysis and could undoubtedly replace the carbon paste grooved electrodes. It can be assumed that certain progress in the development of electrode materials was achieved by this research

Construction of some new simple malachite green ion-selective electrodes

The construction and performace characteristics of different types of malachite green ion-selective electrodes are described. These electrodes were prepared either by coating different substrates (metal wires, carbon rode, glass electrode, solid contact electrodes) or like conventional polymeric membrane electrodes with an electroactive material containing malachite green tetraphenylborate ionexchanger and poly(vinyl chloride) plasticized with dibutyl phthalate, or like a carbon paste-based electrode containing the same ion-pair and tricresyl phosphate. Properties of these electrodes were studied. When used for direct potentiometric determination of malachite gree, the electrodes showed Nernstian responses over the concentration range of 1.0x10(-6) - 1.0x10(-3) moll(-1). Their application to the potentiometric titration of malachite green with tetraphenylborate was studied using automated titration mode

Přenosný biosenzor pro analýzu tenzidů

Sensitive potentiometric enzymatic biosensor was constructed and applied for analysis surfactants based on their inhibitory effect on acetylcholinesterase enzyme (AChE). The enzymatic activity was measured through monitoring hydrolysis of acetylcholine (Ach) with a disposable acetylcholine potentiometric sensor. Based on inhibition of AChE, different cationic, anionic and nonionic surfactants were determined in the concentration range from 0 to 40 µg mL-1 with detection limits reaching 0.07 µg mL-1 (depending on the nature of surfactants). The degree of AChE inhibition caused by different tested surfactants were as follows: cetylpyridinium chloride (CPC) > benzyldimethylhexadecyl ammonium chloride (BDHAC) > Hyamine (Hy) > cetyltrimethylammonium bromide (CTAB) > Triton X-100 (TX-100) > sodium dodecyl sulphate (SDS). The proposed method was applied for determination of surfactants in pharmaceutical formulation, detergents products and environmental samples.Byl připraven citlivý potenciometrický enzymatický biosenzor, který byl použit k analýze povrchově aktivních látek na základě jejich inhibičního účinku na enzym acetylcholinesterázu (AChE). Enzymatická aktivita byla monitorována sledováním hydrolýzy acetylcholinu (ACh) tímto potenciometrickým čidlem. Na základě inhibičního účinku na acetylcholinesterázu byly stanoveny různé kationtové, aniontové a neiontové povrchově aktivní látky na v koncentračním rozmezí od 0 do 40 μg ml-1 s detekční limity až 0,07 μg ml-1 (v závislosti na charakteru povrchově aktivních látek). Stupeň inhibice AChE způsobený vlivem testovaných tenzidů se snižoval v pořadí chlorid cetylpyridinia (CPC) > chlorid benzyldimethylhexadecylamonia (BDHAC) > Hyamin (Hy) > bromid cetyltrimethylamonia (CTAB) > Triton X-100 (TX-100) > dodecylsíran sodný (SDS). Navržená metoda byla použita při stanovení povrchově aktivních látek ve farmaceutických a detergentových přípravcích i ve a vzorcích životního prostředí

Investigation of carbon paste electrodes as supports for gold films in potentiometric stripping determination of coper(II) and mercury(II) traces

Carbon paste electrodes containing either silicone or paraffin oil as pasting liquids have been investigated as possible supports for gold film formed either in situ or by electrodeposition. These electrodes, preplated with a thin gold film, were tested for stripping potentiometric determinations of traces of copper(II) and mercury(II). A detailed study has shown that the results obtained using these inexpensive and easily prepared electrodes are comparable with those obtained using conventional glassy carbon electrodes. Under optimized experimental conditions, low detection limits and good precision werw obtained. Compared with mercury film electrodes , the copper determination was more favorable on gold film electrodes due to lower RSD and higher slope of calibration curves

Extractive spectrophotometric determination of sulphonamide drugs in pure and pharmaceutical preparations through ion-pair formation with molybdenum(V) thiocyanate in acidic medium

A simple and sensitive extraction-spectrophotometric method is described for the determination of sulfonamide drugs, namely sulphamethoxazole, sulphaguanidine, sulphaquinoxaline, sulphametrole and sulphadimidine, in both pure form and in the dosage forms available in Egyptian markets. The method is based on ion-pair formation between the sulphonamides and Mo(V)-thiocyanate inorganic complex in a sulphuric acid medium followed by extraction of the coloured ion-pairs with 1,2-dichloroethane. The optimum conditions are established. The method permits the determination of sulphonamide drugs over the concentration range of 5–50 μg ml−1. The Sandell sensitivity (S), molar absorptivity, correlation coefficient and regression equations, and limits of detection (LOD) and quantification (LOQ) are calculated. The law values of standard deviation (0.09–0.38) and relative standard deviation (0.10–0.550) reflect the accuracy and precision of the proposed method. The method is applicable for the assay of the investigated drugs in different dosage forms and the results are in good agreement with those obtained by the official pharmacopeial method

Nanomaterial-Based Carbon Paste Electrodes for Voltammetric Determination of Naproxen in Presence of Its Degradation Products

The present work describes a novel, simple, and fast electroanalytical methodology for naproxen (NAP) determination in pharmaceutical formulations and biological fluids in the presence of its degradation products. Carbon paste electrodes (CPEs) modified with different carbon nanomaterials, namely, glassy carbon powder (GCE), multiwall carbon nanotubes (MWCNTs), single-walled carbon nanotubes (SWCNTs), graphene nanosheets (Gr), and graphene oxides (GO) were tested. Comprehensive studies were performed on the electrode matrix composition including the nature of the pasting liquids, pH, carbon nanomaterials, and mode of electrode modification. Two anodic oxidation peaks were recorded at 0.890 and 1.18 V in 1 × 10−1 mol·L−1 phosphate buffer solution at pH 6. Oxidation of naproxen (NAP) is an irreversible diffusion-controlled process. Calibration plots were rectilinear in the concentration ranging from 0.067 to 1.0 µg·mL−1 with correlation coefficient 0.9979. Photodegradation of NAP resulted in disappearance of the oxidation peak at 1.18 V, allowing simultaneous determination of NAP in presence of its degradation product. The achieved high sensitivity and selectivity suggest the application of the proposed protocol for naproxen determination in pharmaceutical preparations and human blood plasma