A new magnetic nanodiamond/graphene oxide hybrid (Fe3O4@ND@GO) material for pre-concentration and sensitive determination of sildenafil in alleged herbal aphrodisiacs by HPLC-DAD system.

A sensitive analytical methodology was investigated to concentrate and determine of sildenafil citrate (SLC) present at trace level in herbal supplementary products. The proposed method is based on simple and sensitive pre-concentration of SLC by using magnetic solid phase extraction with new developed magnetic nanodiamond/graphene oxide hybrid (Fe3O4@ND@GO) material as a sorbent. Experimental variables affecting the extraction efficiency of SLC like; pH, sample volume, eluent type and volume, extraction time and amount of adsorbent were studied and optimized in detail. Determination of sildenafil citrate after magnetic solid phase extraction (MSPE) was carried out by HPLC-DAD system. The morphology, composition, and properties of the synthesized hybrid material was characterized by Fourier transform infrared spectrometry (FT-IR), Raman spectrometry (Raman), X-ray diffraction spectrometry (XRD), scanning electron microscopy (SEM), mapping photographs, zeta potential analyzer, and BET surface area analysis. Under optimized conditions, linear range was ranged from 5.00 to 250.00 ng mL-1 with R2 of 0.9952. The limit of detection (LOD) was 1.49 ng mL-1 and the recoveries at two spiked levels were ranged from 94.0 to 104.1% with the relative standard deviation (RSD) < 7.1% (n = 5). The enhancement factor (EF) was 86.9. The results show that the combination MSPE with HPLC-DAD is a suitable and sensitive method for the determination of SLC in real samples.

Removal of uranyl ions in aquatic mediums by using a new material: gallocyanine grafted hydrogel.

A new material containing gallocyanine (GC) grafted polyacyril amide (PAA) was synthesized and its adsorption ability was examined for the removal of uranyl ions from aqueous media. The new developed adsorbent was characterized by FTIR, SEM, and PZC analysis. Adsorption of UO2(2+) ions from aqueous solution as a function of ion concentration, pH, ionic strength, temperature, and reusability of adsorbent was investigated in detail. The adsorption data were analyzed by using the Langmuir, Freundlich and Dubinin-Radushkevich (DR) models. The adsorption of UO2(2+) increased with pH and reached a plateau value in the pH range 5-6. The adsorption of UO2(2+) ions were not affected by increasing ionic strength. The adsorption mechanism followed an endothermic and spontaneous process with increased disorderliness at adsorbate/adsorbent interface. The adsorption process followed a pseudo-second-order kinetics. The new developed material is a potential adsorbent for effective removal of uranyl ions from aquatic solutions.

A micellar improved method for trace levels selenium quantification in food samples, alcoholic and nonalcoholic beverages through CPE/FAAS.

A useful preconcentration and determination method was proposed for trace selenium in food samples. The procedure is based on complex formation of Pyronine B with Se(IV) ions in the presence of sodium dodecyl sulphate (SDS) and Ponpe 7.5. The variables affecting complex formation, extraction and phase separation were studied and optimised. Under the experimental conditions used, the calibration graph was linear in the range of 20-1700 µg L(-1) for Se(IV) ions. The limit of detection was 3.81 µg L(-1) of Se(IV) and the relative standard deviation for 5 replicate determinations at 250 µg L(-1) concentration level was 2.45%. Recovery values were obtained between 97.8% and 102.8% for spiked samples. The method was successfully applied to the determination of total selenium in some food samples and alcoholic and nonalcoholic beverages. Its validity was checked by the analysis of four certified reference materials. The results obtained by the proposed method were quantitatively in good agreement with the certified values.