Achieving 100% Efficient Postcolumn Hydride Generation for As Speciation Analysis by Atomic Fluorescence Spectrometry

Abstract

An experimental setup consisting of a flow injection hydride generator coupled to an atomic fluorescence spectrometer was optimized in order to generate arsanes from tri- and pentavalent inorganic arsenic species (iAs(III), iAs(V)), monomethylarsonic acid (MAs(V)), and dimethylarsinic acid (DMAs(V)) with 100% efficiency with the use of only HCl and NaBH4 as the reagents. The optimal concentration of HCl was 2 mol L(-1); the optimal concentration of NaBH4 was 2.5% (m/v), and the volume of the reaction coil was 8.9 mL. To prevent excessive signal noise due to fluctuations of hydride supply to an atomizer, a new design of a gas-liquid separator was implemented. The optimized experimental setup was subsequently interfaced to HPLC and employed for speciation analysis of arsenic. Two chromatography columns were tested: (i) ion-pair chromatography and (ii) ion exchange chromatography. The latter offered much better results for human urine samples without a need for sample dilution. Due to the equal hydride generation efficiency (and thus the sensitivities) of all As species, a single species standardization by DMAs(V) standard was feasible. The limits of detection for iAs(III), iAs(V), MAs(V), and DMAs(V) were 40, 97, 57, and 55 pg mL(-1), respectively. Accuracy of the method was tested by the analysis of the standard reference material (human urine NIST 2669), and the method was also verified by the comparative analyses of human urine samples collected from five individuals with an independent reference method.

Efficient Photochemical Vapor Generation of Molybdenum for ICPMS Detection

“…An introduction of volatile species to the ICPMS spray chamber was ultimately adopted because these fluctuations of analyte supply were smoothed by the additional dead volume in the spray chamber. A very similar situation arises with classical hydride generation, as encountered when coupling to an atomic fluorescence spectrometer operating with a diffusion flame atomizer …”

“…A very similar situation arises with classical hydride generation, as encountered when coupling to an atomic fluorescence spectrometer operating with a diffusion flame atomizer. 38 Argon (chemifold) carrier flow was optimized using 30% formic acid and 1 μg L −1 Mo standard to establish conditions for efficiently transferring the volatile species to the ICP from the photoreactor. The gas stream leaving the GLS was mixed with an additional flow of argon (not shown in Figure 1) before it was introduced into the spray chamber; care was taken to keep the total gas flow to the ICP the same, so as to not influence conditions in the plasma or sampling depth.…”

Calix[4]arene Derivative-Modified Glassy Carbon Electrode: A New Sensing Platform for Rapid, Simultaneous, and Picomolar Detection of Zn(II), Pb(II), As(III), and Hg(II)

“…These toxins enter into the body of living organisms through the food chain and induce severe health effects. − Some HMs such as iron, cobalt, zinc, copper, and manganese are important in trace amounts, but their excess leads to toxic effects in humans. , While other HMs, that is, lead, arsenic, mercury, cadmium, etc., are considered highly toxic even at very low concentrations. The toxicity of these HMs is declared by the “Agency for Toxic Substances and Disease Registry Priority List of Hazardous Substances” and World Health Organization (WHO). − The excess of HMs results in enzyme inhibition, oxidative stress, and impaired antioxidant metabolism. Moreover, these have been reported to cause lethal effects in living organisms by free-radical generation and could end up with mutations in DNA, − reduction of protein sulfhydryl, and lipid peroxidation. ,, For instance, the presence of Pb­(II) ions above a certain level of its threshold causes neurodegenerative diseases, kidney damage, bone growth retardation, hyperirritability, and ataxia .…”

A Novel Pretreatment Device Integrating Magnetic-Assisted Dispersive Extraction and Ultrasonic Spray Separation for Speciation Analysis of Arsenic in Whole Blood by Ion Chromatography-Inductively Coupled Plasma-Mass Spectrometry

“…The direct method is to extract and purify the target analyte directly from the blood matrix through physical and chemical approaches, e.g., electrodialysis, , electromembrane extraction, , hydride generation, microdialysis, etc. In the arsenic speciation extraction of blood, electrodialysis/electromembrane extraction faces difficulty in separating neutral molecules such as As­(III) existing in the nonionized form of H 3 AsO 3 under acidic or neutral conditions; high generation efficiency of hydride generation is difficult to be obtained simultaneously for various arsenic species; microdialysis is relatively low in extraction efficiency . Therefore, it is difficult to guarantee the efficient extraction of all target arsenic species by the above methods at the same time.…”