جستجوی مقالات مرتبط با کلیدواژه "detection limit" در نشریات گروه "شیمی"

Cephalexin monohydrate can be detected using potentiometric sensors made of coated wire electrodes. The Cephalexin monohydrate sensor was made of cerium oxide nanoparticles that were made using green synthesis techniques. At concentrations of 3.0×10-9-1.0×10-2 mol.L-1, an excellent response was observed with values of -54.78 and -54.76 mV.decade-1, respectively. The detection limits were between 4.0×10-2 and 9.8×10-2 mol.L-1 for CEX-PT-CeO2 NPs containing a sensor's leaves extract of Myrtus communis and CEX-PT-CeO2 NPs containing a sensor's leaves extract of Mentha. For CEX-PT-CeO2 NPs with Myrtus communis sensor leaves extract and CEX-PT-CeO2 NPs with Mentha sensor leaves extract, the PH ranged from 3.5 to 6.5, and the lifetime was 52 days. With concentrations of 8.0×10-10-1.0×10-2 mol.L-1, the CEX-PT-CeO2 NPs sensor displayed a non-Nernstian response close to -35.96 mV.decade-1, limit of detection of 4.0×10-10 mol. L-1, with a pH of 3.0-8.0. As a CEX-PT-CeO2 NPs sensor, a new coated wire electrode was developed in this study. The limit of detection, selectivity, and concentration range of the two sensors were all very high. These sensors were used to find Cephalexin monohydrate in pharmaceutical and pure products.

Ranitidine ion-selective membrane electrodes were fabricated from PVC matrix and ranitidine hydrochloride (RNH-HCl)-phosphotungestic acid (PTA) as the detecting components in the existence of di-n-octyl phthalate (DOPH), di-n-butyl phthalate (DBPH) and dibutyl phosphate (DBP) as the solvent mediator and plasticizing the PVC membrane. The electrodes were prepared with DOPH (electrode 1), and DBPH (electrode 2) gave a Nernstian, stable, and rapid response, which displayed linear response in the concentration range of 1.0×10-6-1.0×10-2 mol.L-1 and 2.03×10-6-1.0×10-2 mol.L-1, with Nernstian slope of 58.73, and 52.50 mV.decade-1 for electrode 1 and electrode 2 respectively. Limits of detection 9.30×10-7 and 3.70×10-7 mol.L-1 for electrodes 1 and 2, respectively were also obtained. Individual electrodes were operative at the pH range of 3.0-5.5 and 3.5-5.5. The membrane electrodes showed excellent selectivity for the drug ranitidine in comparison with various inorganic cations. The electrodes showed a cycle of 55,50 days not including major variations in the parameters of the electrodes. Sensor 3 was given a non-Nernstian response equal to 28.76 mV.decade-1 and the range of concentration was   2.0×10-6-1.0×10-2 mol.L-1 with a limit of detection near 3.68×10-7 mol.L-1. Ranitidine can be determined effectively in unmixed and pharmaceutical formulations using these designated methods.

A potentiometric response of an ion-selective electrode with a new ionophore 8,11,14-triaza-1,4-dioxo-5(6),16(17)-ditolylcycloseptadecane (TADODTSD) toward Cr(III) ions was studied. The designed electrode showed a Nernstian behavior with a slope of 19.6±0.5mV/decade in a working concentration range of 1.0×10-8-1.0×10-1 mol L-1 and a detection limit of 8.0×10-8 mol L-1. A membrane composition made of PVC: DBP: ionophore (TADODTSD): NaTPB; 30%: 60%: 8%: 2 wt.% displays the best results. Response time was found to be 7 seconds and can be used for 120 days without showing any substantial deviation in potential. The proposed electrode exhibits selectivity for Cr(III) ions. The electrode worked well under laboratory conditions with its, potential response being constant over a pH range of 3.0-8.0. The electrode proposed in this work could be used to determine the presence of Cr(III) ion in wastewater and also an indicator electrode with EDTA.

Electrochemical investigations of 4-aminoantipyrine (4-AA) at polyglycine modified glassy carbon electrode (poly(glycine)MGCE) was carried out in acidic phosphate buffer medium. 4-AA exhibited a well-defined oxidation peak at a potential of 0.446 V with an oxidation current of 5.72 μA. Compared to the oxidation currents obtained by bare glassy carbon electrode (GCE) and modified electrode, poly(glycine)MGCE exhibited good catalytic activity towards the determination of 4-AA. Results of scan rate investigation indicate that electrode process was diffusion controlled. Effect of concentration of the analyte on current was studied. With the help of calibration curve, detection limit was calculated and was found to be 0.97 nM. Prepared electrode was applied for the recovery study of drug in urine with spiked as well as real samples.

Novel polymeric membrane electrode based on o-hydroxyacetophenone carbohydrazone (OHAC) as a neutral ionophore carrier has been prepared and explored as silver(I) ion selective electrode. The addition of lipophilic anion excluder (NaTBP) and various plasticizers viz. o-nitrophenyl octyl ether (o-NPOE), dibutyl phthalate (DBP) and butyl acetate (BA) have found to improve the performance of membrane sensor which have a composition of I:NaTBP:NPOE:PVC in the ratio 3:2:62:33 (w/w; mg). The electrode exhibit Nernstian slope for silver (I) ions over wide concentration ranges from 1.0×10-7 M to 1.0×10-2 M with limits of detection 1.6×10-7 M. The response time was found to be 10 s. The potentiometric responses were independent of the pH of the test solutions in the pH range of 3.0 to 8.0. The proposed electrode revealed good selectivity over a wide variety of other cations including alkali, alkaline earth, transition and heavy metal ions. The proposed PVC electrode was used as an indicator electrode in the potentiometric titration of Ag+ ions with KI and NaCl solutions and in direct determination in different water samples and urine sample of peoples working as jewelry maker.