Highly selective solid phase extraction and preconcentration of Azathioprine with nano-sized imprinted polymer based on multivariate optimization and its trace determination in biological and pharmaceutical samples.

In this research, for first time selective separation and determination of Azathioprine is demonstrated using molecularly imprinted polymer as the solid-phase extraction adsorbent, measured by spectrophotometry at λmax 286nm. The selective molecularly imprinted polymer was produced using Azathioprine and methacrylic acid as a template molecule and monomer, respectively. A molecularly imprinted solid-phase extraction procedure was performed in column for the analyte from pharmaceutical and serum samples. The synthesized polymers were characterized by infrared spectroscopy (IR), field emission scanning electron microscopy (FESEM). In order to investigate the effect of independent variables on the extraction efficiency, the response surface methodology (RSM) based on Box-Behnken design (BBD) was employed. The analytical parameters such as precision, accuracy and linear working range were also determined in optimal experimental conditions and the proposed method was applied to analysis of Azathioprine. The linear dynamic range and limits of detection were 2.5-0.01 and 0.008mgL-1 respectively. The recoveries for analyte were higher than 95% and relative standard deviation values were found to be in the range of 0.83-4.15%. This method was successfully applied for the determination of Azathioprine in biological and pharmaceutical samples.

Highly selective determination of amitriptyline using Nafion-AuNPs@branched polyethyleneimine-derived carbon hollow spheres in pharmaceutical drugs and biological fluids.

In this paper, AuNPs@Polyethyleneimine-derived carbon hollow spheres were synthesized by a versatile and facile method in three steps and successfully developed and validated as Amitriptyline sensor using cyclic voltammetry (CV), chronoamperometry (CA) and differential pulse voltammetry (DPV) methods. The characterization of the electrode surface has been carried out by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), x-ray photo-electron spectrum (XPS), electrochemical impedance spectroscopy (EIS) and chronocoulometry (CC). The obtained negatively charged modified electrode was highly selective to Amitriptyline and it was shown a wide linear range from 0.1 to 700µmolL(-1), with a lower detection limit of 0.034µmolL(-1) (n=5, S/N=3), revealing the high-sensitivity properties. The modified electrode is used to achieve the real-time quantitative detection of AMT for biological applications, and satisfactory results are obtained. Due to the advantages of the sensor, its selectivity, sensitivity and stability, it will have a bright future in the field of medical diagnosis.

Voltammetric determination of dopamine at a zirconium phosphated silica gel modified carbon paste electrode.

Zirconium phosphated amorphous silica gel (devoted briefly as Si-ZrPH) modified carbon paste electrode (CPE) was used for detection of dopamine (DA) in the presence of ascorbic acid (AA) and uric acid (UA). Cyclic voltammetry demonstrated improved reversibility of the DA on the modified electrode. Cyclic voltammetry of Fe(CN)(6)(3-/4-) as a negatively charged probe revealed that the surface of the Si-ZrPH modified CPE surface had a high density of negative charge. As a result, the modified carbon paste electrode could inhibit the voltammetric response of AA and UA while the redox reaction of dopamine was promoted. Based on this, a selective method has been developed to detect DA in the presence of 2500 and 1000 time higher concentration of AA and UA, respectively. The effect of various experimental parameters on the voltammetric response of dopamine was investigated. Under the chosen conditions, the differential pulse voltammetry peak current was found to be linear with DA concentration in the ranges of 0.04 to 50 microM and 50 to 400 microM. The detection limit of the proposed method in the presence of 100 microM of AA and 40 microM of UA was found to be 0.02 microM for DA determination. Satisfying results are achieved when detecting the DA in injection and human serum samples.