fast determination
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2022 ◽  
Vol 54 (2) ◽  
Author(s):  
Khaled Elsayed ◽  
Walid Tawfik ◽  
Ashraf E. M. Khater ◽  
Tarek S. Kayed ◽  
Mohamed Fikry

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nieves Carro ◽  
Ana Mouteira ◽  
Isabel García ◽  
María Ignacio ◽  
Julio Cobas

AbstractA fast, effective and low cost sample preparation method based on miniaturized matrix solid-phase dispersion (micro-MSPD) combined with gas chromatography coupled to tandem triple-quadrupole-mass spectrometry (GC–MS/MS) has been developed for the determination of six phthalate diesters (DMP, DEP, DBP, BzBP, DEHP and DnOP) in mussel samples. The six target compounds have been included in the list of priority pollutants by United States Environmental Protection Agency. The extraction step was optimized on real spiked mussel coming from Galician Rías by means of a factorial design. The final procedure involved the use of 0.45 g of sample, 0.5 g of dispersant agent (Florisil) and 3 mL of organic solvent (ethyl acetate). The optimized method was validated giving satisfactory analytical performance, low detection limits (0.09 to 6.73 ng g−1 dw) and high recoveries (93 and 114%). The validated method was applied to four real mussel samples coming from Galician Rías.


2021 ◽  
Vol 8 (32) ◽  
pp. 178-197
Author(s):  
Soraya Blum ◽  
Felipe Zahrebelnei ◽  
Noemi Nagata ◽  
Valtencir Zucolotto ◽  
Luiz Mattoso ◽  
...  

Efforts have been made on the development of new modified electrodes to be used in the fast determination of neurotransmitters, either in commercial drugs or in biological samples. Determination of dopamine (DA), for example, is of great importance since the lack of this neurotransmitter is related to many neurological disorders, including Parkinson’s and Alzheimer’s diseases. In this paper, we present a detailed electrochemical characterization, as well as DA detection studies of paste electrodes incorporating carbon materials in different allotropic forms, including carbon black modified with intrinsically conducting polymers (Eeonomers®), pristine carbon black, graphite, and carbon nanotubes. Emphasis is put on the smaller particle size and larger specific surface area of CB Eeonomers® materials, which led to an improved electroanalytical performance for the developed devices. The electrodes fabricated with Eeonomers® modified with polyaniline exhibited the higher current response towards DA detection, in addition to the ability of distinguishing DA from its natural interferent, ascorbic acid. Furthermore, a central composite design was used to investigate the influence of pH and electrode composition (proportion of Eeonomers®) on the electrochemical sensing of DA. A greater sensitivity was achieved for 50:50 (w/w) KP20/KPy20 electrode at pH 7.0. The optimized devices showed to be promising tools to perform quick, cheap and sensitive detection of this neurotransmitter in bioanalytical systems.


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