A Simple Organic Solvent-Free Liquid-Liquid Microextraction Method for the Determination of Potentially Toxic Metals as 2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol Complex from Food and Biological Samples

Dispersed Solidified Fine Droplets Based on Sonication of a Low Melting Point Deep Eutectic Solvent: a Novel Concept for Fast and Efficient Determination of Cr(VI) in Urine Samples

Cr(VI) has carcinogenic effects, so determination of trace amount of chromium in human body such as urine has a great deal of importance. In this work, a novel microextraction method was developed based on solidification of dispersed fine droplets (SDFD) of a low melting point deep eutectic solvent (DES), produced with the aid of sonication, for fast and efficient determination of Cr(VI) in urine samples. Cr(VI) contents of the human urine samples were first complexed using 1,5-diphenylcarbazone at pH ≈ 2.0 and then extracted by the method. A cloudy solution was achieved by the sonication of a microliter volume of a new water-immiscible DES consisting of benzyltriphenylphosphonium bromide (BTPPB) and phenol. Low freezing point of DES makes it possible to use simple, precise, and fast collection of the extraction phase by solidification and the subsequent centrifugation. Finally, the sedimented phase was diluted with methanol and analyzed by electrothermal atomic absorption spectrometry (ETAAS). The influences of the main factors on the efficiency of the procedure were investigated by a four-factor central composite design (CCD). Under the optimum conditions, the calibration curve was linear within the range of 10-1000 ng L^-1. The intra- and inter-day RSD% values of 2.6 and 4.7% were obtained at the concentration of 50.0 ng L^-1, respectively. The limits of detection (LOD) and quantification (LOQ) were calculated as 2.0 and 7.0 ng L^-1, respectively. Moreover, compared to the other approaches, the proposed method presented better or comparable analytical performance and provided accurate, precise, and reliable results for trace analysis of Cr(VI) in urine samples.

A fast and simple air-assisted liquid-liquid microextraction procedure for the simultaneous determination of bisphenols, parabens, benzophenones, triclosan, and triclocarban in human urine by liquid chromatography-tandem mass spectrometry

The increasing awareness and public concern with hazard exposure to endocrine-disrupting chemicals calls for methods capable to handle numerous samples in short analysis time. In this present study, a novel method combining air-assisted liquid-liquid microextraction and liquid chromatography coupled to mass spectrometry was developed and validated for the extraction, preconcentration, and determination of 7 bisphenols (bisphenol A, bisphenol S, bisphenol AP, bisphenol P, bisphenol F, bisphenol AF, bisphenol Z), 7 parabens (methyl-, ethyl-, propyl-, butyl-, benzyl-paraben, methyl-protocatechuic acid, and ethyl-protocatechuic acid), 5 benzophenones (benzophenone-1, benzophenone-2, benzophenone-3, benzophenone-8, and 4-hydroxybenzophenone), and two antimicrobials (triclosan and triclocarban) in human urine samples. Type and volume of solvent, extraction time (cycles), pH sample, ionic strength, agitation, and needle dimensions were evaluated. The matrix-matched calibration curves of all analytes were linear with correlation coefficients higher than 0.99 in the range level of 1.0-20.0 ng mL^-1. The relative standard deviation, precision, at three concentrations (1.0, 10.0 and 20.0 ng mL^-1) was lower than 15% with accuracy ranging from 90% to 114%. The biomonitoring capability of the new proposed method was confirmed with the analysis of 50 human urine samples randomly collected from Brazilian children. High urinary concentrations of several EDCs associated with usage of personal care products were found.

Triethylenetetramine modified multiwalled carbon nanotubes for the efficient preconcentration of Pb(ii), Cu(ii), Ni(ii) and Cd(ii) before FAAS detection

Triethylenetetramine modified multiwalled carbon nanotubes (TETA-MWCNTs) were prepared and used as an efficient adsorbent for the solid phase extraction of heavy metal ions.