scholarly journals New Modified Electrodes of Graphite paste with Nano Silicon dioxide For Determination of Sildenafil citrate Drug

2019 ◽  
Vol 24 (6) ◽  
pp. 57
Author(s):  
Aveen K. Mohammed1 ◽  
Ali I. Khaleel1 ◽  
, Nawzad N. Ahmed2
Keyword(s):  
Silicon Dioxide ◽  
Limit Of Detection ◽  
Pharmaceutical Preparation ◽  
Modified Electrodes ◽  
Life Time ◽  
Sildenafil Citrate ◽  
Optimum Ph ◽  
Ph Range ◽  
Optimum Ph Range

In this research, new graphite paste electrodes modified with silicon dioxide (SiO2) nano particle are constructed and used for the determination of Viagra drug (Sildenafil citrate, SILC). The electrodes are constructed by preparing ion-pair for (SILC) with phosphotungstic acid (PTA) or phosphomolybdic (PMA) acid using dibutyl phthalate (DBP) as a plasticizer. These electrodes show good sensitivity towards SILC with linear range of (1.0´10-7-1.0´10-2) M, correlation coefficient, (0.9990) and the life time (120) days for both electrodes, limit of detection  (5.177´10-8 and 5.026´10-8) M, optimum temperature range (23-50 and 23-65)oC , slope (57.33 and 58.01) mV/decade and optimum pH range (2-6 and 2-5), for SILC-PTA and SILC-PMA electrodes respectively. These electrodes were successfully applied for determination of SILC in pure and pharmaceutical preparation form (tablets) with recovery of not less than 98% .   http://dx.doi.org/10.25130/tjps.24.2019.109

scholarly journals Determination of moxifloxacin hydrochloride in AVELOX pharmacological formulations using modified potentiometer sensors

Polimery ◽  
2021 ◽  
Vol 66 (11-12) ◽  
pp. 589-601
Author(s):  
Sachin Kumar ◽  
Sushil K. Sindhu ◽  
Praveen Kumar ◽  
Amit Sharma ◽  
Suresh Sagadevan
Keyword(s):  
Limit Of Detection ◽  
Modified Electrodes ◽  
Phosphomolybdic Acid ◽  
Official Method ◽  
Carbon Paste ◽  
Limit Of Quantification ◽  
Highly Sensitive ◽  
Electrode Sensor ◽  
Ph Range

Three different carbon paste (CP), silk-screen (SP) and poly (vinyl chloride) (PVC) modified electrodes were obtained to verify the reliability of AVELOX, the generic name of which is Moxifloxacin HCl (AV-MOXH). The sensing membranes were containing AVELOX ion associated complexes with sodium tetraphenylborate (NaTPB), phosphomolybdic acid (PMA), phosphotungstic acid (PTA), and ammonium reineckate (RN) as electroactive materials. All three electrodes gave fast, viable, and near-Nernstian linear responses over a relative wide concentration range that ranged from 1.010-6 to 1.010-2 mol / L AV-MOXH at 25° C with a monovalent cationic decrease. The sensors demonstrated a good discernment of AV-MOXH from numerous inorganic and organic compounds such as glucose, sucrose, Na+, Ca+, etc. Additionally, the isothermal coefficients along with selectivity coefficients were calculated. The modified Screen Printed Electrode sensor appeared to be highly sensitive for the determination of AV-MOXH. The electrode response was observed in pH range 2--6 for ISPE electrodes and IPVC electrodes and 3--7 for ICPE electrodes under various temperature conditions. The short response time, lifetime validity, recovery, and all the methods of validation such as limit of detection and limit of quantification were estimated. The potentiometric method turned out to be suitable for determining AV-MOXH in pharmacological formulations, and the findings obtained are comparable to the “HPLC official method” in terms of the agreement. As a result, the postulated potentiometric approach was verified in accordance with IUPAC guidelines.

scholarly journals Determination of optimal adsorption-desorption conditions for selective removal of Ni(II) from petrochemical samples using ion imprinted nanosorbent

2018 ◽  
Vol 9 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Azizallah Nezhadali ◽  
Maryam Pirouzmand ◽  
Mahmood Payehghadr
Keyword(s):  
Limit Of Detection ◽  
Modified Electrodes ◽  
Imprinted Polymer ◽  
Cyclic Voltammetric ◽  
Relative Standard ◽  
Ion Imprinted ◽  
Optimum Ph ◽  
Maximum Sorption ◽  
Adsorption Desorption

Nanoporous particles Ni(II) ion imprinted polymer (IIP), and non-imprinted polymer (NIP) in the absence of Ni(II) ion, with 18-70 nm dimensions were synthesized, and characterized by Fourier transform infrared, energy dispersive X-ray and nuclear magnetic resonance spectroscopic methods. Then, the surface area, pore size and structural composition of the products were characterized by Brunauer-Emmett-Teller and scanning electron microscope methods. Then, modified electrodes by the IIP for Ni(II) sensing and determination, were constructed and their catalytic activity were investigated by cyclic voltammetric method. Some parameters like desorption solvent, amount of sorbent, pH and contact time were optimized, and the measurements were all conducted under optimal conditions. The optimum pH for maximum sorption was obtained 7.8. In the optimum conditions, the maximum sorbent capacity of the IIP was obtained 371.9 µM/g. The limit of detection and relative standard deviation (n = 5) were obtained 1.3 ng/mLand 1.47%, respectively. The pre-concentration procedure revealed a linear curve within the concentration range of 10-6000 ng/mL and a good linearity with squared correlation coefficient of r2 0.9991 was achieved. The method was applied successfully for determination of Ni(II) ion in petrochemical samples.

Spectrophotometric determination of zinc with 5-methyl-1,3,4-thiadiazolyl-(2-azo-1)-2-naphthol

1983 ◽  
Vol 48 (2) ◽  
pp. 464-470 ◽  
Author(s):  
Juan Cacho ◽  
Cristina Nerin
Keyword(s):  
Spectrophotometric Determination ◽  
Organic Phase ◽  
Molar Absorptivity ◽  
Beer's Law ◽  
Optimum Ph ◽  
Beer’S Law ◽  
Ph Range ◽  
Optimum Ph Range

The reaction of Zn(II) with 5-methyl-1,3,4-thiadiazolyl-(2-azo-1)-2-naphthol (MTDAN) and extraction of the complex formed in chloroform is studied. The optimum pH range for the extraction and formation of the complex is 10-11.2 and Beer's law is obeyed in the interval of 0-2 ppm of Zn(II) in the organic phase. The molar absorptivity is 5.9 . 104 l mol-1 cm-1 at 568 nm. The stoichiometry of the complex corresponds to the type ML2. Some interferences are studied and an easy way is given to eliminate them. The results are compared with those corresponding to TAN. The reaction is applied to the analysis of synthetic samples of bronzes with satisfactory results.

Indirect Determination of Amikacin by Gold Nanoparticles as Redox Probe

2020 ◽  
Vol 17 ◽  
Author(s):  
Mansureh Alizadeh ◽  
Mandana Amiri ◽  
Abolfazl Bezaatpour
Keyword(s):  
Gold Nanoparticles ◽  
Bacterial Infections ◽  
Limit Of Detection ◽  
Pharmaceutical Preparation ◽  
Cathodic Peak ◽  
Easy Method ◽  
Peak Current ◽  
Indirect Determination ◽  
Tract Infections

: Amikacin is an aminoglycoside antibiotic used for many gram-negative bacterial infections like infections in the urinary tract, infections in brain, lungs and abdomen. Electrochemical determination of amikacin is a challenge in electroanalysis because it shows no voltammetric peak at the surface of bare electrodes. In this approach, a very simple and easy method for indirect voltammetric determination of amikacin presented in real samples. Gold nanoparticles were electrodeposited at the surface of glassy carbon electrode in constant potential. The effect of several parameters such as time and potential of deposition, pH and scan rates on signal were studied. The cathodic peak current of Au3+ decreased with increasing amikacin concentration. Quantitative analysis of amikacin was performed using differential pulse voltammetry by following cathodic peak current of gold ions. Two dynamic linear ranges of 1.0 × 10−8–1.0 × 10-7 M and 5.0 × 10−7–1.0 × 10-3 M were obtained and limit of detection was estimated 3.0× 10−9 M. The method was successfully determined amikacin in pharmaceutical preparation and human serum. The effect of several interference in determination of amikacin was also studied.

Novel palladium(II) selective membrane electrode based on 4-[(5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl]benzene-1,3-diol

2010 ◽  
Vol 75 (5) ◽  
pp. 563-575 ◽  
Author(s):  
Moslem Mohammadi ◽  
Mehdi Khodadadian ◽  
Mohammad K. Rofouei
Keyword(s):  
Limit Of Detection ◽  
Membrane Electrode ◽  
Aqueous Samples ◽  
Selective Determination ◽  
Poly Vinyl Chloride ◽  
Selective Membrane ◽  
Ph Range ◽  
Palladium Content ◽  
Methyl Benzene

A plasticized poly(vinyl chloride) membrane electrode based on 4-[(5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl]benzene-1,3-diol (L) for highly selective determination of palladium(II) (in PdCl42– form) is developed. The electrode showed a good Nernstian response (29.6 ± 0.4 mV per decade) over a wide concentration range (3.1 × 10–7 to 1.0 × 10–2 mol l–1). The limit of detection was 1.5 × 10–7 mol l–1. The electrode has a response time of about 20 s, and it can be used for at least 2 months without observing any considerable deviation from Nernstian response. The proposed electrode could be used in the pH range of 2.5–5.5. The practical utility of the electrode has been demonstrated by its use for the estimation of palladium content in aqueous samples.

scholarly journals Surface-Enhanced Oxidation and Determination of Isothipendyl Hydrochloride at an Electrochemical Sensing Film Constructed by Multiwalled Carbon Nanotubes

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
S. N. Prashanth ◽  
Shankara S. Kalanur ◽  
Nagappa L. Teradal ◽  
J. Seetharamappa
Keyword(s):  
Limit Of Detection ◽  
Biological Fluids ◽  
Differential Pulse ◽  
Electrochemical Sensing ◽  
Good Precision ◽  
Multiwalled Carbon ◽  
Limit Of Quantification ◽  
Surface Enhanced ◽  
Ph Range

The electrochemical behavior of isothipendyl hydrochloride (IPH) was investigated at bare and multiwalled-carbon-nanotube modified glassy carbon electrode (MWCNT-GCE). IPH (55 μM) showed two oxidation peaks in Britton-Robinson (BR) buffer of pH 7.0. The oxidation process of IPH was observed to be irreversible over the pH range of 2.5–9.0. The influence of pH, scan rate, and concentration of the drug on anodic peak was studied. A differential pulse voltammetric method with good precision and accuracy was developed for the determination of IPH in pure and biological fluids. The peak current was found to be linearly dependent on the concentration of IPH in the range of 1.25–55 μM. The values of limit of detection and limit of quantification were noticed to be 0.284 and 0.949 μM, respectively.

scholarly journals Extraction-Chromogenic System for Cobalt Based on 5-Methyl-4-(2-thiazolylazo) Resorcinol and Benzalkonium Chloride

2021 ◽  
Vol 68 (1) ◽  
pp. 37-43
Author(s):  
Danail G. Georgiev Hristov ◽  
Petya Vassileva Racheva ◽  
Galya Konstantinova Toncheva ◽  
Kiril Blazhev Gavazov
Keyword(s):  
Benzalkonium Chloride ◽  
Limit Of Detection ◽  
Ion Association ◽  
Molar Absorptivity ◽  
Sensitivity Limit ◽  
Deprotonated Form ◽  
Limit Of Quantification ◽  
Optimum Ph ◽  
Ion Associate ◽  
Ph Range

The interaction between CoII and 5-methyl-4-(2-thiazolylazo)-resorcinol (MTAR) was studied in a water-chloroform system, in the presence or absence of benzalkonium chloride (BZC) as a cationic ion-association reagent. The optimum pH, concentration of the reagents and extraction time for the extraction of Co were found. In the presence of BZC, the extracted ion-associate could be represented by the formula (BZ+)[CoIII(MTAR2–)2], where MTAR is in its deprotonated form. The following extraction-spectrophotometric characteristics were determined: absorption maximum, molar absorptivity, Sandell’s sensitivity, limit of detection, limit of quantification, constant of extraction, distribution ratio and fraction extracted. In the absence of BZC, the extraction is incomplete and occurs in a narrow pH range. The extracted chelate contains one deprotonated and one monoprotonated ligand: [CoIII(MTAR2–)(HMTAR–)].

scholarly journals Haem disorder in modified myoglobins. Effect of reconstitution procedures

1983 ◽  
Vol 215 (1) ◽  
pp. 117-122 ◽  
Author(s):  
M B Ahmad ◽  
J R Kincaid
Keyword(s):  
Selective Oxidation ◽  
High Spin ◽  
Chromatographic Purification ◽  
Optimum Ph ◽  
Ph Range ◽  
Optimum Ph Range

Apomyoglobin was reconstituted with deuterohaem derivatives under various conditions. The fraction of disordered component, which is characterized by a 180 degree rotation of the haem group, for the various preparations was determined by n.m.r. spectroscopy. By using the procedures described, it was shown that the fraction of disordered component is minimized if the reconstitution is carried out with high-spin ferric haem derivatives within an experimentally determined optimum pH range of 8-9.5. Use of low-spin derivatives in either the ferrous or ferric forms leads to substantial increases in the fraction of disordered form. Attempted removal of the disordered form by selective oxidation and chromatographic purification was not effective.

CHARACTERISTICS OF FOUR RHIZOBIOPHAGES ACTIVE AGAINST RHIZOBIUM MELILOTI

1957 ◽  
Vol 3 (4) ◽  
pp. 651-668 ◽  
Author(s):  
D. T. Parker ◽  
O. N. Allen
Keyword(s):  
Rhizobium Meliloti ◽  
The Other ◽  
Cross Reactions ◽  
Thermal Death ◽  
Optimum Ph ◽  
Ph Range ◽  
Optimum Ph Range ◽  
Standard Techniques

Four phage isolates for strains of Rhizobium meliloti were obtained from sewage and held soil and purified by standard techniques. Plaque sizes ranged from 1.0 to 4.0 mm. The titers of these phages remained unchanged after 24 months' storage at 0° and 4 °C. None of the phages lysed all of the 38 strains of R. meliloti tested, although 29 of these strains were lysed by one of the phages. Of 292 other strains of rhizobia isolated from 108 species of 50 leguminous genera, one of the phages lysed six strains, another, five strains, while the other two phages did not lyse any. None of the phages lysed any of the 40 strains of Agrobaderium and Chromobaderium species tested. Inactivation rates of the four phages by their homologous antisera were linear up to 90% inactivation. Cross-reactions with heterologous antisera showed weak serological relationships between some of the phages. The latent periods of growth ranged from 80 to 90 minutes to 170–180 minutes. Burst sizes of rhizobia infected by the four phages ranged from 80 to 317 particles per bacterium after an adsorption period of 60 minutes at 30 °C. The optimum pH range was 6.4–7.8. Thermal death points in broth were 51 °C, 53 °C, 61 °C, and 70 °C, respectively, for the four phages.

scholarly journals Validation of a Thin-Layer Chromatography for the Determination of Hydrocortisone Acetate and Lidocaine in a Pharmaceutical Preparation

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Małgorzata Dołowy ◽  
Katarzyna Kulpińska-Kucia ◽  
Alina Pyka
Keyword(s):  
Chromatographic Analysis ◽  
Limit Of Detection ◽  
Pharmaceutical Preparation ◽  
Lidocaine Hydrochloride ◽  
Hydrocortisone Acetate ◽  
Limit Of Quantification ◽  
Bioactive Substances ◽  
Densitometric Detection ◽  
Layer Chromatography

A new specific, precise, accurate, and robust TLC-densitometry has been developed for the simultaneous determination of hydrocortisone acetate and lidocaine hydrochloride in combined pharmaceutical formulation. The chromatographic analysis was carried out using a mobile phase consisting of chloroform + acetone + ammonia (25%) in volume composition 8 : 2 : 0.1 and silica gel 60F254plates. Densitometric detection was performed in UV at wavelengths 200 nm and 250 nm, respectively, for lidocaine hydrochloride and hydrocortisone acetate. The validation of the proposed method was performed in terms of specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and robustness. The applied TLC procedure is linear in hydrocortisone acetate concentration range of3.75÷12.50 μg·spot−1, and from1.00÷2.50 μg·spot−1for lidocaine hydrochloride. The developed method was found to be accurate (the value of the coefficient of variation CV [%] is less than 3%), precise (CV [%] is less than 2%), specific, and robust. LOQ of hydrocortisone acetate is 0.198 μg·spot−1and LOD is 0.066 μg·spot−1. LOQ and LOD values for lidocaine hydrochloride are 0.270 and 0.090 μg·spot−1, respectively. The assay value of both bioactive substances is consistent with the limits recommended by Pharmacopoeia.

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