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High-performance liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS2) with a triple quadrupole is proposed for determining the synthetic phosphodiesterase-5 inhibitors, sildenafil, tadalafil and vardenafil, and the active metabolite N-desmethyl sildenafil. The method was successfully applied to the analysis of waters of different origins and human urine samples. Dispersive...
A graphene oxide (GO) suspension was used to retain chromium (III) species in a neutral solution. The addition of Triton X-45 followed by heating resulted in a coacervate, to which the GO nanoparticles containing the analyte retained were transferred. Chromium was determined directly in the surfactant-rich phase by electrothermal atomic absorption spectrometry. The procedure was repeated using a second...
A micro-solid phase extraction procedure for the separation and preconcentration of antimony based in the use of magnetic particles covered with silver nanoparticles functionalized with the sodium salt of 2-mercaptoethane-sulphonate (MESNa) is discussed. After separation by means of a magnetic field, the solid phase is directly introduced into an electrothermal atomizer for antimony determination...
The cloud point extraction (CPE) of silver nanoparticles (AgNPs) by Triton X-114 allows chromium (III) ions to be transferred to the surfactant-rich phase, where they can be measured by electrothermal atomic absorption spectrometry. Using 20mL sample and 50μL Triton X-114 (30% w/v), the enrichment factor was 1150, and calibration graphs were obtained in the 5–100ngL −1 chromium range in the...
The dispersive liquid–liquid microextraction of edible oils with a low volume of an acidic solution in the presence of isopropyl alcohol allows cadmium and lead to be completely separated into the aqueous phase. After centrifugation, the metals are determined by electrothermal atomization atomic absorption spectrometry using a palladium salt for chemical modification in the heating cycle. Using a...
Pressurized liquid extraction (PLE) and dispersive liquid–liquid microextraction (DLLME) were used to isolate and preconcentrate tocopherols and tocotrienols from plant foods. The Taguchi experimental method was used to optimize the six factors (three levels for each factor), affecting DLLME, namely: carbon tetrachloride volume, methanol volume, aqueous sample volume, pH of sample, sodium chloride...
A simple and rapid method was developed using reversed-phase liquid chromatography (LC) with both diode array (DAD) and atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection, for the simultaneous analysis of the vitamins ergocalciferol (D 2 ), cholecalciferol (D 3 ), phylloquinone (K 1 ), menaquinone-4 (K 2 ) and a synthetic form of vitamin...
A microextraction procedure for the speciation of very low concentrations (0.005–0.2µgL −1 ) of chromium is discussed. To the aqueous sample (10mL), diluted hydrochloric acid, sodium chloride and a small amount of tributylphosphate (80µL) are incorporated, and the mixture is submitted to ultrasounds for 10min. The organic phase recovered after centrifuging is injected into the electrothermal...
A procedure for the determination of ultratrace levels of lead and cadmium using dispersive liquid–liquid microextraction followed by electrothermal atomic absorption spectrometry (ETAAS) has been developed. The ionic liquid, 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C 8 MIm][NTf 2 ]), is formed in situ and used to extract the lead and cadmium complexes with ammonium...
This study describes a method for coupling dispersive liquid–liquid microextraction (DLLME) and normal-phase liquid chromatography (NP-LC) with fluorescence detection for vitamin A determination with the view to developing a new green sample preparation technique. Parameters affecting DLLME, including the nature and volume of both extractant and disperser solvents, salt addition and time and speed...
A procedure for the determination of inorganic arsenic (III, V) and antimony (III, V) in water samples by using a miniaturized solid-phase extraction with carbon nanotubes followed by electrothermal atomic absorption measurement is proposed. The trivalent species are first complexed with ammonium pyrrolidinedithiocarbamate, next retained in a mini-column containing nanotubes and then eluted by means...
A new method for the electrothermal atomic absorption spectrometric determination of vanadium in milk and infant formulas using suspensions to avoid the need for previous dissolution of samples is described. Sensitivity is improved by a procedure based on preconcentration and removal of the matrix, using ion-exchange (Dowex 1X8-100). Suspensions of 15% (m/v) infant formula samples were prepared in...
A computer-controlled manifold allowing the automatic generation of concentration profiles is described. For this purpose, the sample or standard solution is placed inside a semi-closed loop to which diluent is incorporated at a given flow rate, while the solution is removed at the same flow rate and directed towards the detector. The flow manifold, which works in a similar way to the tank model,...
The advantages of using membrane micropumps to introduce sample or standard solutions in flame atomic absorption spectrometry are discussed, using two entirely computer-controlled manifolds which allow a wide range of dispersion coefficients to be obtained. Coupling micropumps to the manifold facilitates calibration graphs to be obtained using a single standard solution. Other advantages include a...
Atomic fluorescence spectrometry was used as an element-specific detector in hybridation with liquid chromatography (LC) and hydride generation for the speciation of Sb(III), Sb(V) and trimethylantimony dichloride (TMSbCl 2 ). The three species were poorly resolved in a single chromatogram but good results were obtained by anion-exchange chromatography, using a mobile phase with 20mM EDTA...
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