Determination of phenol, m-, o- and p-cresol, p-aminophenol and p-nitrophenol in urine by high-performance liquid chromatography.
ABSTRACT A method for the biological monitoring of human exposure to aromatic hydrocarbons, nitrocompounds, amines and phenols has been developed. Phenol, cresols, p-aminophenol, p-nitrophenol and their glucorono- or sulpho-conjugates, were quantified by HPLC; 4-chlorphenol was added as internal standard. After enzymatic hydrolysis, the free compounds were extracted with an organic solvent and analyzed by an isocratic HPLC Perkin Elmer system at ambient temperature and at a flow-rate of 1 ml/min. The column was a reversed-phase Pecosphere 3 x 3 C18 Perkin Elmer; the mobile phase was a 30:70:0.1 (v/v/v) methanol-water-orthophosphoric acid mixture and the chromatogram was monitored at 215 nm. Identification was based on retention time and quantification was performed by automatic peak height determination, corrected for the internal standard. The recovery was ca. 95% for phenol and cresols; 90% for p-nitrophenol; 85% for p-aminophenol; the coefficients of variance were less than 6% within analysis (n = 20) and less than 10% between analysis (n = 20). The detection limits, at a signal/noise ratio of 2, were 0.5 mg/l for phenol and cresols and 1 mg/l for p-aminophenol and p-nitrophenol.
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ABSTRACT: Semiconductor doped nanostructure materials have attained considerable attention owing to their electronic, opto-electronic, para-magnetic, photo-catalysis, electro-chemical, mechanical behaviors and their potential applications in different research areas. Doped nanomaterials might be a promising owing to their high-specific surface-area, low-resistances, high-catalytic activity, attractive electro-chemical and optical properties. Nanomaterials are also scientifically significant transition metal-doped nanostructure materials owing to their extraordinary mechanical, optical, electrical, electronic, thermal, and magnetic characteristics. Recently, it has gained significant interest in manganese oxide doped-semiconductor materials in order to develop their physico-chemical behaviors and extend their efficient applications. It has not only investigated the basic of magnetism, but also has huge potential in scientific features such as magnetic materials, bio- & chemi-sensors, photo-catalysts, and absorbent nanomaterials. RESULTS: The chemical sensor also displays the higher-sensitivity, reproducibility, long-term stability, and enhanced electrochemical responses. The calibration plot is linear (r2 = 0.977) over the 0.1 nM to 50.0 muM 4-nitrophenol concentration ranges. The sensitivity and detection limit is ~4.6667 muA cm-2 muM-1 and ~0.83 +/- 0.2 nM (at a Signal-to-Noise-Ratio, SNR of 3) respectively. To best of our knowledge, this is the first report for detection of 4-nitrophenol chemical with doped Mn2O3-ZnO NPs using easy and reliable I-V technique in short response time. CONCLUSIONS: As for the doped nanostructures, NPs are introduced a route to a new generation of toxic chemo-sensors, but a premeditate effort has to be applied for doped Mn2O3-ZnO NPs to be taken comprehensively for large-scale applications, and to achieve higher-potential density with accessible to individual chemo-sensors. In this report, it is also discussed the prospective utilization of Mn2O3-ZnO NPs on the basis of carcinogenic chemical sensing, which could also be applied for the detection of hazardous chemicals in ecological, environmental, and health care fields.Chemistry Central Journal 03/2013; 7(1):60. · 1.31 Impact Factor
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ABSTRACT: We have prepared low-dimensional silver oxide nanoparticles (NPs) by a sono-chemical methodusing reducing agents in alkaline medium. The resulting NPs were characterized by UV/vis and FT-IRspectroscopy, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray energydispersive spectrometry (XEDS), and field-emission scanning electron microscopy (FESEM). They weredeposited on a flat-polycrystalline gold electrode (AuE, surface area, 0.0216 cm2) to give a sensor witha fast response toward 4-nitrophenol (4-NPh) in liquid phase. The sensor also displays good sensitiv-ity and long-term stability, and enhanced electrochemical performances. The calibration plot is linear(r2= 0.9873) over the large concentration range (LDR, 1.0 �M to 0.5 mM). The sensitivity and detectionlimit is calculated to ∼4.740 �A cm−2mM−1and ∼0.19 �M (signal-to-noise ratio, at a SNR of 3), respec-tively. We also discuss possible future prospective uses of this metal oxide nanomaterials in terms ofchemical sensing.Electrochimica Acta 12/2013; 112:422– 430. · 3.78 Impact Factor
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ABSTRACT: A carbon paste electrode modified with p-chloranil and carbon nanotubes was used for the sensitive and selective voltammetric determination of hydroxylamine (HX) and phenol (PL). The oxidation of HX at the modified electrode was investigated by cyclic voltammetry (CV), chronoamperommetry, and electrochemical impedance spectroscopy. The values of the catalytic rate constant (k), and diffusion coefficient (D) for HX were calculated. Square wave voltammetric peaks current of HX and PL increased linearly with their concentrations at the ranges of 0.1-172.0 and 5.0-512.0 μmol L(-1), respectively. The detection limits for HX and PL were 0.08 and 2.0 μmol L(-1), respectively. The separation of the anodic peak potentials of HX and PL reached to 0.65 V, using square wave voltammetry. The proposed sensor was successfully applied for the determination of HX and PL in water and wastewater samples.Environmental Science and Pollution Research 04/2013; · 2.62 Impact Factor