Iranian Journal of Analytical Chemistry
Volume:2 Issue: 1, Winter and Spring 2015

In this study, a sensitive method of dispersive liquid phase microextraction based on ion-pair combined with the flame atomic absorption spectrometry was proposed for the determination of trace Ni(II) using Aliquat 336-chloride as ion pair agent. Several factors which have effect on  the microextraction efficiency of Ni(II), such as pH, extraction and dispersive solvent type and their volume, concentration of the Aliquat 336-chloride, extraction time were investigated and the optimized experimental conditions were established. After extraction, the enrichment factor was 47. The detection limit of the method was 8.0 µg L-1 and the relative standard deviation for eight determinations of 100 µg L-1 Ni(II) was 2.1 %. The results for the determination of Ni(II) in food samples (black tea, lettuce, parsley and carrot) have demonstrated the accuracy, recovery and applicability of the proposed method.

In the present work, a new kind of alumina-based adsorbent with high selectivity and stability and efficient adsorption was prepared. Alumina was coated with an oxazolone azo dye, 2-(4-{2-[4-(dimethylamino) phenyl]-1-diazenyl}phenyl)-4-[1-phenyl methylidene]-5(4H)-oxazolone, and then used for preconcentration of trace amounts of palladium. The analytical procedure involved the complex formation of Pd with oxazolone azo dye as a chelating agent in buffer media of pH 5. The stability of sorbent was excellent and adsorption capacity did not change significantly after 100 consecutive uses of 50.0 mg of modified alumina. Under the optimum conditions, the preconcentration factor of the method was 150. The linearity was maintained in the concentration range of 0.33 ng mL-1 to 8.0 mg mL-1 in the original solution. For 2.0 µg mL-1 of Pd, the relative standard deviation 1.4% and detection limit 0.25 ng mL-1 was obtained. The proposed method was successfully applied to the determination of trace amounts of palladium in the anodic slime and wastewater samples.

The present study was aimed to develop and validate a high performace liquid chromatography method for determination of thiocolchicoside and dexketoprofen trometamol in combined dosage form. The proposed HPLC method utilizes an Agilent Eclipse C-8 column (5 µm, 250×4.6 mm) at ambient temperature. A 23 full factorial design was performed for optimization of mobile phase for separation of two drugs. For the factorial design, the dependent variables chosen were % of acetonitrile, % of 0.1% o-phosphoric acid and pH. The optimum mobile phase consisted of acetonitrile: 0.1% o-phosphoric acid in water (41.9:58.1; pH 2.6). The flow rate was kept 1 mL/min with UV detection at 254 nm. The run time was found to be 1.41 min and 7.58 min for thiocolchicoside and dexketoprofen trometamol, respectively. The method was validated as per ICH guidelines. The calibration plots were linear in the range of 1-5 μg/mL with r2=0.998 for thiocolchicoside and 6-30 μg/mL with r2 = 0.995 for dexketoprofen trometamol. The % recovery values were found to be 98.52 ± 1.21 and 98.16 ± 1.45 for thiocolchicoside and dexketoprofen trometamol, respectively. The minimum detectable and minimum quantifiable amounts were found to be 0.11 and 0.35 μg/mL, respectively for thiocolchicoside and 1.41 and 4.38 μg/mL, respectively for dexketoprofen trometamol. The developed method could be utilized successfully in simultaneously analyzing the drugs in bulk as well as combined dosage form.

The corrosion inhibition characteristics of two synthesized Schiff bases, namely N, N´-bis(2-hydroxy-6-nitrobenzaldehyde) benzidine  and N, N´-bis(salysylaldehyde) benzidine, on the mild steel corrosion in 2.0 M hydrochloric acid have been investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy techniques. These studies were carried out at different concentrations, temperatures and durations. Polarization measurements indicate that the two inhibitors act as mixed type inhibitors. The adsorption of inhibitors obeys the Langmuir adsorption isotherm and the thermodynamic parameters (Ea, Kads, ΔG0ads) were calculated and discussed. Quantum chemical calculations were performed to provide further insight into the inhibition efficiencies determined experimentally.

A simple, inexpensive and efficient method was used for extraction and determination of Fexofenadine and Levocetirizine with three–phase hollow fiber liquid-phase microextraction and high-performance liquid chromatography. Several parameters influencing the extraction recoveries such as the nature of organic extraction solvent, pH of donor and acceptor phases, stirring rate, extraction time and salt addition to the sample solution (donor phase) were investigated and optimized. Under the optimized conditions (toluene as organic solvent, pHdonor = 2.5, pHacceptor = 12.0, stirring rate of 1000 rpm, extraction time of 30 min, with no salt addition), extraction recoveries were 64% for Fexofenadine and 79% for Levocetirizine. A good clean-up sample with excellent linearities in the range of 1–500 ng/mL for Fexofenadine (R2=0.997) and 0.6-600 ng/mlfor Levocetirizine (R2=0.998) were obtained. The limits of detection were 0.3 ng/mL for Fexofenadine and 0.2 ng/mL for Levocetirizine.

This research is on the improvement of the procedure to determination of trace levels of antidepressant drug; fluoxetine in wastewaters. In this research a silica based sol-gel was applied for the extraction of fluoxetine from water samples. This two-phase technique is consisting of aqueous samples of fluoxetine (donor phase) and silica based nanocomposite prepared by sol-gel technique (acceptor phase). Accepter phase was held in the pores and lumen of polypropylene hollow fiber segment. Microextraction experiments were carried out in two steps; extraction from analyte samples by sorbent which is held into the hollow fiber segment and desorption of drug from hallow fiber by using of methanol. Desorbed analyte in order to measurement were offered to HPLC and UV-V is spectrophotometer for further analysis. This method is simple, fast and adopted by a majority of   the instrumental methods. Extraction parameters such as sol-gel aging time, pH of donor phase, volume of donor phase, extraction time, stirring rate and effect of surfactant were investigated and optimized. The measurements were done under the optimal conditions. This technique has many advantages, such as the short extraction time, low consumption of organic solvents, elimination of carry-over effect, low limit of detection and high pre-concentration factor. The pre-concentration factor and limit of detection have been gained 3227 and 0.53 ng mL-1, respectively. The linear range and relative standard deviation are 1.0-10000.0 ng mL-1 and 4.8%  (n=3), respectively.

Spectrophotometric and electrochemical studies were successfully used in quantitative analysis of Amitriptyline Hydrochloride (ATH) and Nortriptyline Hydrochloride (NTH). Conductometric titration were carried out in equeous solution using iodide and dopamine and serotonine as titrant. Two new methods using spectrophotometry are dascribed for the determination of (ATH) and (NTH) with potassium bromate as the oxidizing agent and acid dyes, Methyl orange and Indigo carmine. Both spectrophotometric methods are based on the oxidation of mentioned drugs by a known excess of bromate in acid medium and in the presence of excess of bromide followed by estimation of surplus oxidant by reacting with either Indigo carmine (method A) or Methyl orange (method B) and measuring the absorbance at 609 or 507 nm.

Eperisone Hydrochloride is a skeletal muscle relaxant and Paracetamol is cyclooxygenase inhibitor. These drugs in combination are used as antispasmodics. A simple, specific, precise and accurate method was developed, namely reverse phase high performance liquid chromatography for simultaneous estimation of Eperisone Hydrochloride and Paracetamol in tablet dosage form. In RP-HPLC method separation was achieved by HiQ silC-18HS column having 250 mm× 4.6 mm, with mobile phase containing Methanol: 0.05 mM Ammonium acetate buffer: Acetonitrile (60:30:10) and adjusted to pH 5.8 using Glacial acetic acid for RP-HPLC system. The flow rate was 1.0 ml/min and effluent was monitored at 264 nm. The retention time of EPR and PAR were 6.45 min and 3.05 min respectively. The linearity for EPR and PAR were in the range of 5-25 µg/mL. The recoveries of EPR and PAR were found in the range of 99.96-100.52% and 99.87-100.11%, respectively. The proposed method was validated as per ICH guidelines and successfully applied to the estimation of EPR and PAR in tablet dosage form.