This review deals with speciation analysis of arsenic based on hydride generation and coupled with analytical atomic spectrometry. Three basic on-line approaches to speciation analysis of arsenic are defined: (a) selective hydride generation, (b) postcolumn hydride generation and (c) generation of methyl substituted arsanes. All of the approaches are discussed with the focus on the latest advances in those fields.

• MeSH
• arsen * analýza   MeSH
• spektrální analýza metody   MeSH
• Publikační typ
• práce podpořená grantem MeSH

This work describes the intricacies of the determination of the trimethylselenonium ion (TMSe) in human urine via high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS). By definition, this technique requires that the separated TMSe can be online converted into a volatile compound. Literature data for the determination of TMSe via the hydride generation technique are contradictory; i.e., some authors claim that direct formation of volatile compounds is possible under reduction with NaBH4, whereas others reported that a digestion step is mandatory prior to conversion. We studied and optimized the conditions for online conversion by varying the mobile phase composition (pyridine, phosphate, and acetate), testing different reaction coils, and optimizing the hydride generation conditions, although technically no hydride (H2Se) is formed but a dimethylselenide (DMSe). The optimized conditions were used for the analysis of 64 urine samples of 16 (unexposed) volunteers and the determination of low amounts of TMSe (LOD = 0.2 ng mL-1). Total (specific gravity-corrected) selenium concentrations in the urine samples ranged from 7.9 ± 0.7 to 29.7 ± 5.0 ng mL-1 for individual volunteers. Four volunteers were characterized as TMSe producers (hINMT genotype GA) and 12 were non-producers (hINMT genotype GG). Urine of TMSe producers contained 2.5 ± 1.7 ng mL-1 of TMSe, compared to 0.2 ± 0.2 ng mL-1 for non-producers.

• MeSH
• fluorescenční spektrometrie MeSH
• lidé MeSH
• selen * moč   MeSH
• sloučeniny selenu * MeSH
• vysokoúčinná kapalinová chromatografie metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

• Klíčová slova
• spektrometrie atomová absorbční,

• Konspekt
• Biochemie. Molekulární biologie. Biofyzika
• NLK Obory
• fyzika, biofyzika
• chemie, klinická chemie

The aim of this study was to develop a method of Se and As determination in drinking water by electrochemical hydride generation coupled with AAS. Three types of electrolytic cells were constructed and optimized for the determination. Two cells (thin-layer and tubular) were finally chosen for their low inner volume and a high hydride generation efficiency (ca. 90 %). The limits of detection of As(III) and Se(IV) were 0.07 and 0.37 ng ml–1, respectively. The accuracy of the method was verified using reference materials.

• MeSH
• arsen analýza   MeSH
• chemické znečištění vody analýza   MeSH
• elektrochemie metody   přístrojové vybavení   MeSH
• selen analýza   MeSH
• vysokoúčinná kapalinová chromatografie metody   přístrojové vybavení   MeSH
• zásobování vodou MeSH

Atomization of hydrides and their methylated analogues in a dielectric barrier discharge (DBD) plasma atomizer was investigated. Selected ion flow tube mass spectrometry (SIFT-MS) was chosen as a detector being capable of selective detection of non-atomized original volatile species allowing thus direct quantification of atomization efficiency. Selenium hydride (SeH2) and three volatile arsenic species, namely arsenic hydride (AsH3), monomethylarsane (CH3AsH2) and dimethylarsane ((CH3)2AsH), were selected as model analytes. The mechanistic study performed contributes to understanding of the atomization processes in atomic absorption spectrometry (AAS). The presented results are compatible with a complete atomization of arsenic hydride as well as its methylated analogues and with atomization efficiency of SeH2 below 80%. Using AsH3 as a model analyte and a combination of AAS and SIFT-MS detectors has revealed that the hydride is not atomized, but decomposed in the DBD atomizer in absence of hydrogen fraction in the carrier gas. Apart from investigation of analyte atomization, the SIFT-MS detector is capable of quantitative determination of water vapor content being either transported to, or produced in the atomizer. This information is crucial especially in the case of the low-power/temperature DBD atomizer since its performance is sensitive to the amount of water vapor introduced into the plasma.

• MeSH
• arsen * MeSH
• hmotnostní spektrometrie MeSH
• nebulizátory a vaporizátory MeSH
• spektrofotometrie atomová MeSH
• vodík MeSH
• Publikační typ
• časopisecké články MeSH

Chalcogen atoms are a class of substituents capable of generating inner and outer derivatives of boron clusters. It is well known that chalcogenated boron clusters can form strong σ-hole interactions when a chalcogen atom is a part of an icosahedron. This paper studies σ-hole interactions of dicarbaboranes with two exopolyhedral chalcogen atoms bonded to carbon vertices. Specifically, a computational investigation has been carried out on the co-crystal of (1,2-C2B10H10)2Se4•toluene and a single crystal of (1,2-C2B10H10)2Te4.

• MeSH
• borany chemie   MeSH
• chalkogeny chemie   MeSH
• krystalizace MeSH
• molekulární modely MeSH
• statická elektřina MeSH
• termodynamika MeSH
• Publikační typ
• časopisecké články MeSH

The development of 1,8-naphthalimide derivatives as DNA-targeting anticancer agents is a rapidly growing area and has resulted in several derivatives entering into clinical trials. One of original recent developments is the use of boron clusters: carboranes and metallacarboranes in the design of pharmacologically active molecules. In this direction several naphthalimide-carborane and metallacarborane conjugates were synthesized in the present study. Their effect on a cancer cell line - cytotoxicity, type of cell death, cell cycle, and ROS production were investigated. The tested conjugates revealed different activities than the leading members of the naphthalimides family, namely mitonafide and pinafide. These derivatives could induce G0/G1 arrest and promote mainly apoptosis in HepG2 cell line. Our investigations demonstrated that the most promising molecule is N-{[2-(3,3'-commo-bis(1,2-dicarba-3-cobalta(III)-closo-dodecaborate-1-yl)ethyl]-1'-aminoethyl)}-1,8-naphthalimide] (17). It was shown that 17 exhibited cytotoxicity against HepG2 cells, activated cell apoptosis, and caused cell cycle arrest in HepG2 cells. Further investigations in HepG2 cells revealed that compound 17 can also induce ROS generation, particularly mitochondrial ROS (mtROS), which was also proved by increased 8-oxo-dG level in DNA. Additionally to biological assays the interaction of the new compounds with ct-DNA was studied by CD spectra and melting temperature, thus demonstrating that these compounds were rather weak classical DNA intercalators.

• MeSH
• borany chemie   farmakologie   MeSH
• buněčné linie MeSH
• buňky Hep G2 MeSH
• DNA nádorová účinky léků   MeSH
• lidé MeSH
• molekulární struktura MeSH
• naftalimidy chemie   farmakologie   MeSH
• organokovové sloučeniny chemická syntéza   chemie   farmakologie   MeSH
• oxidační stres účinky léků   MeSH
• proliferace buněk účinky léků   MeSH
• protinádorové látky chemická syntéza   chemie   farmakologie   MeSH
• screeningové testy protinádorových léčiv MeSH
• vazebná místa MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Inorganic As(III) and As(V), and methylated As(V) are the most frequent species found in natural waters. This article provides information about the determination of these species by hydride-generation AAS or hydridegeneration electrothermal AAS using different reaction media.

• MeSH
• arsen analýza   MeSH
• chemické látky znečišťující vodu analýza   MeSH
• finanční podpora výzkumu jako téma MeSH
• spektrofotometrie atomová MeSH

The interest in the determination of different Sb species in natural waters is due to the fact that their toxicological and physiological behavior strongly depends on their chemical forms and oxidation states. The purpose of this article is to review and evaluate methods for Sb speciation in waters based on selective hydride generation of Sb (III) and on coupling of different separation techniques (liquid-liquid extraction, solid phase extraction, cloud point extraction, ion-exchange HPLC and GC) with atomic spectrometric methods (AAS, atomic emission spectrometry and atomic fluorescence spectrometry). This review covers the literature published over the period 1998-2006.

• MeSH
• antimon analýza   MeSH
• financování organizované MeSH
• látky znečišťující vodu analýza   MeSH
• plynová chromatografie s hmotnostně spektrometrickou detekcí MeSH

A proof of concept of a novel pervaporation sequential injection (PSI) analysis method for automatic non-chromatographic speciation analysis of inorganic arsenic in complex aqueous samples is presented. The method is based on hydride generation of arsine followed by its on-line pervaporation-based membrane separation and CCD spectrophotometric detection. The concentrations of arsenite (As(III)) and arsenate (As(V)) are determined sequentially in a single sample zone. The leading section of the sample zone merges with a citric acid/citrate buffer solution (pH 4.5) for the selective reduction of As(III) to arsine while the trailing section of the sample zone merges with hydrochloric acid solution to allow the reduction of both As(III) and As(V) to arsine at pH lower than 1. Virtually identical analytical sensitivity is obtained for both As(III) and As(V) at this high acidity. The flow analyzer also accommodates in-line pH detector for monitoring of the acidity throughout the sample zone prior to hydride generation. Under optimal conditions the proposed PSI method is characterized by a limit of detection, linear calibration range and repeatability for As(III) of 22 μg L(-1) (3sblank level criterion), 50-1000 μg L(-1) and 3.0% at the 500 μg L(-1) level and for As(V) of 51 μg L(-1), 100-2000 μg L(-1) and 2.6% at the 500 μg L(-1) level, respectively. The method was validated with mixed As(III)/As(V) standard aqueous solutions and successfully applied to the determination of As(III) and As(V) in river water samples with elevated content of dissolved organic carbon and suspended particulate matter with no prior sample pretreatment. Excellent relative recoveries ranging from 98% to 104% were obtained for both As(III) and As(V).

• MeSH
• arseničnany izolace a purifikace   MeSH
• arsenikové přípravky chemie   MeSH
• arsenitany izolace a purifikace   MeSH
• chemické látky znečišťující vodu izolace a purifikace   MeSH
• kalibrace MeSH
• koncentrace vodíkových iontů MeSH
• kyselina citronová chemie   MeSH
• limita detekce MeSH
• průtoková injekční analýza metody   MeSH
• řeky chemie   MeSH
• spektrofotometrie přístrojové vybavení   metody   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH