11 research outputs found
A Java Chemical Structure Editor Supporting the Modular Chemical Descriptor Language (MCDL)
Abstract: A compact Modular Chemical Descriptor Language (MCDL) chemical structure editor (Java applet) is described. The small size (approximately 200 KB) of the applet allows its use to display and edit chemical structures in various Internet applications. The editor supports the MCDL format, in which structures are presented in compact canonical form and is capable of restoring bond orders as well as of managing atom and bond drawing overlap. A small database of cage and large cyclic fragment is used for optimal representation of difficult-to-draw molecules. The improved algorithm of the structure diagram generation can be used for other chemical notations that lack atomic coordinates (SMILES, InChI)
Multielement Determination of Trace Heavy Metals in Water by Microwave-Induced Plasma Atomic Emission Spectrometry after Extraction in Unconventional Single-Salt Aqueous Biphasic System
For the first time
liquid–liquid extraction was used for
the preconcentration of heavy metals prior to their determination
in water by microwave-induced plasma atomic emission spectrometry
(MP-AES). Extraction of PbÂ(II), CdÂ(II), CoÂ(II), NiÂ(II), ZnÂ(II), and
CuÂ(II) was performed in unconventional aqueous biphasic system (ABS)
formed by addition of hydrophobic solid salt, namely, tetrahexylammonium
bromide, to aqueous sample, with neither organic solvents nor salting-out
agents being used. The metal ions were quantitatively recovered with
4-(2-pyridylazo)-resorcinol (PAR). The extract was diluted with ethanol/HCl
and introduced directly into an MP-AES instrument. The factors influencing
extraction (pH, reagent concentration, phase contact time, etc.) and
MP-AES detection parameters were studied and optimized. For the developed
method, limits of detection of 1.3, 4.9, 0.06, 1.2, 4.2, and 3.2 μg
L<sup>–1</sup> were obtained for cadmium, cobalt, copper, nickel,
lead, and zinc, respectively, providing from 60- to 500-fold improvement
as compared with the analysis without preconcentration. The method
was applied for the analysis of two certified reference materials
(CRM) of wastewater and surface water as well as the samples of well
and seawater. Coupling MP-AES with ABS extraction significantly extends
the capabilities of the method, especially for the analysis of high
salinity waters