Zobrazeno 1 - 10
of 123
pro vyhledávání: '"Valfredo Azevedo Lemos"'
Autor:
Regina Terumi Yamaki, Daniel Rodrigues Vieira, Cleber Galvão Novaes, Hygor Rodrigues de Oliveira, Valfredo Azevedo Lemos, Sandra Carvalho
Publikováno v:
Química Nova, Vol 32, Iss 7, Pp 1943-1946 (2009)
The pKa values of the 6-[2´-(6´-methyl-benzothiazolylazo)]-1,2-dihydroxy-3,5-benzenedisulfonic acid (Me-BDBD) have been determined at 25 °C, in 0.10 mol L-1 NaCl medium by spectrophotometric method. The SQUAD computer program was used to process e
Externí odkaz:
https://doaj.org/article/9601afffb4b5466cbf0795a32bb3dc5c
Autor:
Jorge S. Almeida, Gabriel L. Santos, Lucilia A. Meira, Ana Carla de Souza Nascimento, Leonardo S. G. Teixeira, Valfredo Azevedo Lemos
Publikováno v:
Food Analytical Methods. 14:596-605
A novel ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) based on melting of the donor phase for the determination of Cd, Cu, and Fe in margarine samples using high-resolution continuum source electrothermal atomic absorption s
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::659e808b0e0616569324ac3cf6c3768c
https://doi.org/10.1007/s12161-020-01897-y
https://doi.org/10.1007/s12161-020-01897-y
Publikováno v:
Food Analytical Methods. 13:1681-1689
Two methods based on direct immersion single-drop microextraction (DI-SDME) and continuous-flow microextraction (CFME) were developed. Both methods were used for the determination of manganese by graphite furnace atomic absorption spectrometry. The r
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::c439a9a00e81c813be56e7e67df3ced6
https://doi.org/10.1007/s12161-020-01794-4
https://doi.org/10.1007/s12161-020-01794-4
Publikováno v:
Analytical Methods. 12:865-871
In the present work, solidified floating organic drop microextraction assisted by ultrasound is proposed as the preconcentration system for the determination of trace amounts of nickel, cobalt and copper by FAAS. The main parameters such as pH, conce
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::5d9581abdaf8421f349b9071831f12de
https://doi.org/10.1039/c9ay02453k
https://doi.org/10.1039/c9ay02453k
Publikováno v:
Brazilian Journal of Development. 6:80593-80629
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::a9e7b823c0e16808f7b6b985a20afe90
https://doi.org/10.34117/bjdv6n10-469
https://doi.org/10.34117/bjdv6n10-469
Publikováno v:
Microchemical Journal. 180:107543
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::28b55927111be7e57792ec2418fa261b
https://doi.org/10.1016/j.microc.2022.107543
https://doi.org/10.1016/j.microc.2022.107543
Autor:
Rosivan dos Santos de Assis, Ricardo J. Cassella, Cleber Galvão Novaes, Valfredo Azevedo Lemos, Luana Bastos Santos, Jeferson Alves Barreto
Publikováno v:
Talanta. 238(Pt 1)
Dispersive liquid-liquid microextraction (DLLME) has recently been widely used in the separation and preconcentration of various chemical species. Among the various approaches using DLLME are systems that use a syringe as an extraction environment. I
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::ea5ba3a9ee473b2790fa2142b5062ad3
https://pubmed.ncbi.nlm.nih.gov/34857335
https://pubmed.ncbi.nlm.nih.gov/34857335
Autor:
Alexilda Oliveira de Souza, Djalma Menezes de Oliveira, Luana Bastos Santos, Valfredo Azevedo Lemos
Publikováno v:
Journal of the Iranian Chemical Society. 16:1879-1889
This work is based on the application of the eggshell membrane (ESM) of fresh chicken as a sorbent in a solid phase extraction procedure for arsenic speciation with detection by electrothermal atomic absorption spectrometry. The ESM can adsorb severa
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::fa089aa71953e3daf5a3c2f10a34ddcd
https://doi.org/10.1007/s13738-019-01665-8
https://doi.org/10.1007/s13738-019-01665-8
Autor:
Walter Nei Lopes dos Santos, Sergio Luis Costa Ferreira, Valfredo Azevedo Lemos, Luana Bastos Santos, Rebeca Moraes Menezes, Rafael Vasconcelos Oliveira
Publikováno v:
TrAC Trends in Analytical Chemistry. 110:357-366
Liquid phase microextraction (LPME) has been widely used in extraction and preconcentration systems as an excellent alternative to conventional liquid phase extraction. In this work, a critical review is presented on LPME-based flow injection preconc
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::d969b18b891aa186236fc253e3795e39
https://doi.org/10.1016/j.trac.2018.11.031
https://doi.org/10.1016/j.trac.2018.11.031
Autor:
Valfredo Azevedo Lemos, Luciana A. Silva, Rosemário Cerqueira Souza, Adriano V.B. Chagas, Sergio Luis Costa Ferreira, Caio S.A. Felix, Raineldes A. Cruz Junior
Publikováno v:
Talanta. 191:479-484
This paper proposes a closed inline system for decomposition of wine, aiming at the determination of lead using electrothermal atomization atomic absorption spectrometry (ETAAS). The system is built using a 0.8 mm diameter PTFE tube, which is wrapped
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::73ae72978daaedab5fc708dfdf611c8b
https://doi.org/10.1016/j.talanta.2018.08.085
https://doi.org/10.1016/j.talanta.2018.08.085