Search results for "phosphoric acid"
showing 10 items of 86 documents
Non-chromatographic speciation of toxic arsenic in vegetables by hydride generation-atomic fluorescence spectrometry after ultrasound-assisted extrac…
2007
A non-chromatographic, sensitive and simple analytical method has been developed for the determination of toxic arsenic species in vegetable samples by hydride generation-atomic fluorescence spectrometry (HG-AFS). As(III), As(V), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) were determined by hydride generation-atomic fluorescence spectrometry using a series of proportional equations. The method is based on a single extraction of the arsenic species considered from vegetables through sonication at room temperature with H(3)PO(4) 1 mol L(-1) in the presence of 0.1% (w/v) Triton XT-114 and washing of the solid phase with 0.1% (w/v) EDTA, followed by direct measurement of the co…
Determination of inorganic species of Sb and Te in cereals by hydride generation atomic fluorescence spectrometry
2011
A non-chromatographic fast, sensitive and easy method has been developed for the determination of Sb(III), Sb(V), Te(IV) and Te(VI) in cereal samples. The procedure is based on ultrasound assisted extraction and determination by hydride generation atomic fluorescence spectrometry (HG AFS). Preliminary studies were made in order to get the best extraction efficiency using 1 mol L-1 phosphoric acid, 1 mol L-1 nitric acid, aqua regia, 1 mol L-1 sulfuric acid and 6 mol L-1 hydrochloric acid. The extraction with aquaregia showed a clear interconversion of the species during the process, being H2SO4 the best extractant with efficiencies greater than 90% from the total content of Sb and Te quantif…
Optimizing the H3PO4 leaching conditions of post-precipitated sewage sludge using response surface methodology
2018
The leaching procedure of post-precipitated aluminium phosphate sludge with dilute phosphoric acid was developed. The leaching offers a route to recover both critical phosphorous from sewage sludge and the metal used in precipitation. Using phosphoric acid as leaching solution makes it possible to continue the recovery process without the need to remove chloride or sulfate anions. The optimization of the leaching was based on experimental three-level-four-variable central composite face-centered design. The four variables included were acid concentration, volume of acid, temperature and time of leaching. The leaching was conducted for dewatered and water-containing sludge (total solid conte…
Studies of polyamines transport through liquid membranes with D2EHPA as a carrier.
2008
The transport of polyamines through the liquid membranes with di‐2‐ethylhexyl phosphoric acid (D2EHPA) was investigated. The study was performed in three main steps: liquid–liquid extraction (LLE), bulk liquid membrane (BLM) extraction, and supported liquid membrane (SLM) extraction. Equilibrium distribution experiments allowed determining the extraction constants and stoichiometric coefficients for each polyamine. It turned out that one amino group binds two molecules of carrier (one D2EHPA dimer) and the extractability of polyamine rises with the increase in number of function groups in the molecule. The BLM and SLM experiments showed that despite considerable differences in distribution …
Multipumping Nitrite Determination in Exhaled Breath Condensate
2006
Abstract A flow system based on multicommutation is proposed for the rapid, clean, and inexpensive determination of nitrites in small volumes of breath condensates. The procedure exploits the colorimetric detection of nitrite with the Griess reagent [0.03% naphthylethylene diamine dihydrochloride (NED), 0.5% sulpfhanilamide, and 3.0% phosphoric acid] in acidic medium at 540 nm correcting the variations of the baseline with measurements at 424 nm. The flow system was designed with a set of solenoid micropumps to minimize sample and reagent consumption and waste generation. The detection limit was estimated as 3.8 ng mL−1 (99.7% confidence level) with a linear response ranging up to 500 ng mL…
4-Nitrophenyl phosphoric acid and its four different potassium salts: a solid state structure and kinetic study
2006
The structures of 4-nitrophenyl phosphoric acid, H2NPP (1), and its four different potassium salts, K(H2NPP)(HNPP) (2), K(HNPP)·CH3OH (3), K(HNPP)·2H2O (4), and K2(NPP)·4H2O (5), were determined by X-ray diffraction methods. These investigations, together with the study of the role of potassium ions in the hydrolysis of 4-nitrophenyl phosphate, provided information about interactions between the acid, monoanionic and dianionic forms of 4-nitrophenyl phosphate and the potassium cations. In the crystalline state, the H2NPP molecules form one-dimensional chains of bifurcated O–H⋯O hydrogen bonds between phosphate groups. A different network, derived from ladder-like chains of the O–H⋯O hydroge…
Hydrolysis of DCNP (a Tabun mimic) catalyzed by mesoporous silica nanoparticles
2015
[EN] The hydrolysis of diethylcyanophosphonate, DCNP (a Tabun simulant) in the presence of mesoporous silica nanoparticles (MSN) has been studied in acetonitrile:water (99.5:0.5 v/v) mixtures using 31P NMR as a suitable technique to follow the DCNP hydrolysis. MSN alone was not capable to induce DCNP hydrolysis, yet MSN in combination with the presence of the bases potassium carbonate, triethylamine or DABCO enhanced DCNP degradation. When MSN was used combined with K2CO3, a hydrolysis of ca. 95% of the initial DCNP after 60 min was observed. In the presence of DABCO, MSN was able to induce the hydrolysis of ca. 90% of DCNP after the same time. However, the DCNP hydrolysis using MSN in the …
Empirical calibration of the clumped isotope paleothermometer using calcites of various origins
2014
We present the first universal calibration of the clumped isotope thermometer for calcites of various mineralizing types. These are an eggshell of an ostrich, a tropical bivalve, a brachiopod shell, cold seep carbonate, and three foraminifera samples that grew between 9 and 38 C. CaCO3 was digested at 90 C using a common acid bath. Considering a difference in phosphoric acid fractionation factors between reaction at 25 and 90 C of 0.069& (Guo et al., 2009), the function between growth temperature T and the excess of 13 C– 18 O bonds in the evolved CO2 is expressed by a linear regression between 1/T 2 and absolute D47 (R 2 = 0.9915):
CCDC 622051: Experimental Crystal Structure Determination
2006
Related Article: I.Mata, E.Espinosa, E.Molins, S.Veintemillas, W.Maniukiewicz, C.Lecomte, A.Cousson, W.Paulus|2006|Acta Crystallogr.,Sect.A:Found Crystallogr.|62|365|doi:10.1107/S0108767306025141
CCDC 622037: Experimental Crystal Structure Determination
2006
Related Article: I.Mata, E.Espinosa, E.Molins, S.Veintemillas, W.Maniukiewicz, C.Lecomte, A.Cousson, W.Paulus|2006|Acta Crystallogr.,Sect.A:Found Crystallogr.|62|365|doi:10.1107/S0108767306025141