جستجوی مقالات مرتبط با کلیدواژه "spectrophotometric" در نشریات گروه "ریاضی"

In this study, the complexation reaction between Alprazolam (ALP) and metal ions (Zn2+, Ni2+, Cu2+ and Co2+) was investigated by using spectrophotometry in ethanol solvent. The stoichiometry of M+/ALP complexes was calculated by applying the Job, molar ratio and Continuous Changes methods and the relevant diagrams were plotted for each metal ions in each method. The results show that the obtained complexes are 1:3. In the Continuous Changes method a defeat was observed at molar fraction of 0.66 for all complexes, which confirms complexes with 1:3 mole ratio. The formation constants of complexes were determined by using nonlinear least square method (KINFIT software) and it was concluded that the stability of complexes is varied in the order Cu2+> Co2+> Ni2+ > Zn2+. Therefore, Cu is the strongest and Zn formed with Alprazolam ligand is the weakest complex.

An analytical methodology based on spectrophotometric and partial least squares (PLS) algorithm for the simultaneous determination of ampicillin and penicillin in human plasma was developed and validated. The multivariate model was developed as a binary calibration model and it was built and validated with an independent set of synthesis and real samples in presence of matrix. It is shown how a developed technique for signal filtering, orthogonal signal correction (OSC), can be applied in multivariate calibration to enhance predictive power. The experimental calibration matrix was constructed with 25 samples. The concentration ranges considered were 1.0-40.0 and 0.5-20.0 μg mL-1 for ampicillin and penicillin, respectively. This procedure allows the simultaneous determination of ampicillin and penicillin in synthetic and human plasma good reliability of the determination was proved. The results obtained by the OSC-PLS and HPLC were statistically compared. Very similar values were found by two methods. No time consuming pretreatment was needed and this method also provides rapid, accurate and economical analysis of these drugs.

A cloud point extraction process using the nonionic surfactant Triton X-114 to extract uranium from aqueous solutions was investigated. The method is based on the complexation reaction of uranium with Arsenazo III and micelle-mediated extraction of the complex. The optimal extraction and reaction conditions (e.g., pH, reagent concentration, effect of time) were studied, and the analytical characteristics of the method (e.g., limit of detection, linear range) were obtained. Linearity was obeyed in the range of 1.0-150.0 ng mL-1 of U(IV) ion. The detection limit of the method was 0.3 ng mL-1 of uranium ion. The interference effect of some anions and cations was also tested. The method was applied to the determination of uranium in water samples.

A novel optical sensor has been proposed for sensitive determination of bismuth ion based on immobilization of 4-(4-nitrophenylazo)-1-naphthol on a triacetylcellulose membrane. Chemical binding of bismuth ions in solution with a 4-(4-nitrophenylazo)-1-naphthol immobilized on the triacetylcelluse surface could be monitored spectrophotometrically. The optode shows excellent response over wide concentration range 0.4-3.6 μg mL-1 bismuth with a limit of detection of 0.14 μg mL-1 bismuth. The influence of factors responsible for the improved sensitivity of the sensor were studied and identified. The response time of the optode was 30 sec for a stirrer solution. The influence of potential interfering ions on the determination of 0.4 μg mL-1 bismuth was studied. The proposed optode was applied to the determination of bismuth in pharmaceutical formulation samples.

A simple, economical, precise and fast visible spectrophotometric method has been developed for the determination of Azathioprine in tablet dosage form. Developed method is based on the formation of extractable colored complex of drug with colouring agent Indigo Carmine and Methyl orange. A wavelength maximum was found to be 683.7 nm and 566 nm. The concentration range of 15-50 μg mL-1 with of percentage recovery 100.05-101.31 %, while the linear regression, LOD and LOQ were 99.42-99.08 %, 0.38 and 0.84 μg mL-1 and 0.74 and 0.18 μg mL-1, respectively. Two new sensitive spectrophotometric methods are proposed for the determination of Azathioprine using bromate-bromide mixture and two dyes, methyl orange and indigo carmine, as reagents. The methods entail the addition of a known excess of bromate-bromide mixture to Azathioprine, in acetic acid medium followed by determination of residual bromine by reacting with a fixed amount of either indigo carmine and measuring the Absorbance at 683.6 nm (Method A) or methyl orange measuring the absorbance at 566 nm (Method B).

The multivariate calibration method, partial least square regression (PLS) was applied for the simultaneous spectrophotometric determination of Lidocaine (LID) and Hydrocortisone acetate (HCA) in their mixtures. The parameters of chemometric technique were optimized and the proposed method was validated with synthetic samples and applied to analyze these drugs in pharmaceutical products with good accuracy and precision. The results were compared with the HPLC method. The squares of correlation coefficients (R2) for predicted LID and HCA with the proposed method in test samples were 0.9970 and 0.9964, respectively. The relative standard deviations for commercial products were less than 1%.

The possibility of application of 4-nitrocatechol (4-NC) - tetrazolium salt - organic solvent systems for liquid-liquid extraction-spectrophotometric vanadium (IV and V) speciation was studied. Six commercially available tetrazolium salts (2,3,5-triphenyltetrazolium chloride (TTC), 3-(2-naphtyl)-2,5-diphenyltetrazolium chloride (Tetrazolium Violet, TV); 3-(4,5-dimethyl-2- thiazol)-2,5-diphenyltetrazolium bromide (Thiazolyl Blue Tetrazolium, MTT), 2-(4-iodophenyl)- 3-(4-nitrophenyl)-5-phenyltetrazolium chloride (INT), 3,3’-(4,4’-biphenylene)bis(2,5- diphenyltetrazolium) chloride (Neotetrazolium chloride, NTC) and 3,3’-[3,3’-Dimetoxy(1,1’- biphenyl)-4,4’-diyl]bis(2,5-diphenyltetrazolium) chloride (Blue Tetrazolium chloride, BTC)) and three organic solvents (chloroform, 1,2-dichloroethane, 1-butanol) were tested in this study. The best results were obtained with MTT and chloroform. A direct, very simple, fast and sensitive procedure for vanadium (IV and V) speciation based on the spectral differences of the extracted ternary complexes of V(IV) and V(V) was developed. It was found that the optimization of the MTT to 4-NC ratio has a key role in the speciation results. At deficiency of 4-NC towards MTT the vanadium(IV) complex absorbed light at 390 and 570 nm, while the V(V) complex absorbed only at 390 nm. The corresponding molar absorptivities were calculated to be εV(IV)390 = 3.6×104 L mol-1 cm-1, εV(IV)570 = 1.7×104 L mol-1 cm-1 and εV(V)390 = 3.1×104 L mol-1 cm-1. The method was applied for vanadium (IV and V) speciation in industrial samples with low Fe and Al content (catalyst for oxidation of SO2) and good results were obtained in terms of precision and accuracy.