Injection Hydride Generation Atomic Fluorescence Research Articles

Masking Agents Evaluation for Lead Determination by Flow Injection-Hydride Generation-Atomic Fluorescence Spectrometry Technique: Effect of KI, L-Cysteine, and 1,10-Phenanthroline.

Hydride generation (HG) of lead technique presents interferences from foreign ions of complex matrix samples. In order to minimize these interferences, the effect of masking agents such as KI, L-cysteine, and 1,10-phenanthroline was studied in the absence and in the presence of selected interfering species (As, Cr, Cu, and Fe). Different modes of addition of masking agents were accomplished, that is, to either sample or KBH4 reducing solution. The lead determinations were performed using a flow injection analysis (FIA) system coupled to HG and atomic fluorescence spectrometry (AFS). The linearity of calibration curves (1–10 μg Pb L−1) was not affected by the addition of the masking agents. The use of KI in the reducing solution diminished interferences from concentrations of As and Cu, while 1,10-phenanthroline showed a positive effect on the interference by As. Moreover, Cr and Cu appeared to be the most serious interfering ions for plumbane (PbH4), because they drastically reduced the analytical signal of lead. Fe did not present any interference under the employed experimental conditions, even at high levels. The accuracy was established through the analysis of certified reference material (i.e., BCR-610, groundwater) using KI as masking agent. The detection limit reached by FIA-HG-AFS proposed methodology was 0.03 μg Pb L−1.

Distribution and Occurrence of Arsenic in Two Typical Chinese Coals

Two complementary methods, float-sink experiment and sequential chemical leaching were used to probe into the occurrence of arsenic in two Chinese coals: Yima (YM) and Datong (DT). Flow injection-hydride generation atomic fluorescence spectrometry was employed to measure the arsenic content in parent coals as well as the size and density-fraction samples. Float-sink experiment indicated that the heavy density fractions were enriched mineral containing arsenic in two bituminous coals studied, as confirmed by the sequential chemical leaching method. Sequential chemical leaching revealed that sulfide arsenic was the primary mode of occurrence (> 50%), stable form also abounded in coal with content between 30 and 40%, and a small amount of arsenic took the occurrence of organic form.

Hydride Generation-Atomic Fluorescence Spectrometric Determination of Cadmium in Pure Copper

An anion exchange-sequential injection hydride generation atomic fluorescence spectrometric procedure was specifically developed for the determination of ultra-trace cadmium in pure copper forbidden by the Restriction of the use of hazardous substances in electrical and electronic equipment (RoHS). A 50 mg l −1 copper concentration was employed in the standard solutions to match the copper matrix in the samples. In the presence of an appropriate amount of hydrochloric acid, the copper matrix was effectively eliminated by selectively absorbing the CdCl 4 2– complex onto a 717 anion exchanger packed mini-column. The present procedure could be used for the determination of cadmium in pure copper with a Cu/Cd mass ratio within the range of 2000–50000. A detection limit of 0.2 μg l −1 was achieved within a linear range of 1.0–25.0 μ g l −1, along with a RSD value of 3.0% (at 3.0 μ g l −1). The procedure was applied for the determination of cadmium in a pure copper sample, and spiking recoveries were also performed.

Combining forms of heavy metal elements in Dianshan Lake sediments and their spatial and temporal variations

Environmental pollution is one of the vertical problems faced in the 21 century. There are numbers of lakes located in China. Poyang Lake, which is the largest freshwater lake in China, is the famous representation. The environmental geochemistry of trace and ultra-trace element As in the sediment-water interface (SWI) of Poyang Lake was investigated in detail. Solutions presented in the project can be summarized as follows: it is the first time to discover that the masking agent of 8-hydroxyquinoline was found to be an efficient agent to eliminate the interference of transition metals in the determination of arsenic species, especially to eliminate As (V) emission with high selection in the matrix of As (III) and As (V) coexisting solution. A sensitive and interference-free procedure has been successfully established for the arsenic speciation on As (HI), As (V), Asorg in pore water samples using flowing injection hydride generation atomic fluorescence spectrometry (FI-HG-AFS). It was observed that the concentrations of arsenic species in porewaters were relatively high. With the variation of the redox in sediments, it is easy to cause the second pollution in overlying waters for their upward diffusion. Arsenic is mainly absorbed onto iron and manganese oxyhydroxides in controlling the behavior of As. The effect factors of the transfer, cycle of arsenic are the redox condition at SWI, disturbance, and microbial action, etc. Arsenic has a directive significance of geochemistry in SWI because arsenic species are concentrated near the SWI and involved in a dynamic cycle with precipitation-dissolution-diffusion-reprecipitation of iron and manganese oxyhydroxides.

Preliminary results on the determination of ultratrace amounts of cadmium in tea samples using a flow injection on-line solid phase extraction separation and preconcentration technique to couple with a sequential injection hydride generation atomic fluorescence spectrometry

In this work, a method was developed for determination of ultra-trace levels of Cd in tea samples by atomic fluorescence spectrometry (AFS). A flow injection solid phase extraction (FI-SPE) separation and preconcentration technique, to on-line couple with a sequential injection hydride generation (SI-HG) technique is employed in this study. Cd was preconcentrated on the SPE column, which was made from a neutral extractant named Cyanex 923, while other matrix ions or interfering ions were completely or mostly separated off. Conditions for the SPE separation and preconcentration, as well as conditions for the HG technique, were studied. Due to the separation of interfering elements, Cd hydride generation efficiency could be greatly enhanced with the sole presence of Co 2+ with a concentration of 200 μg L −1, which is much lower than those in other works previously reported. Interferences on both the Cd separation and preconcentration, and Cd hydride generation (HG) were investigated; it showed that both the separation and preconcentration system, and the HG system had a strong anti-interference ability. The SPE column could be repeatedly used at least 400 times, a R.S.D. of 0.97% was obtained for 6 measurements of Cd with 0.2 μg L −1 and a correlation coefficiency of 1.0000 was obtained for the measurement of a series of solutions with Cd concentrations from 0.1 to 2 μg L −1. The method has a low detection limit of 10.8 ng L −1 for a 25 mL solution and was successfully validated by using two tea standard reference materials (GBW08513 and GBW07605).

Determination of As(III) and As(V) in soils using sequential extraction combined with flow injection hydride generation atomic fluorescence detection

An analytical procedure for determination of As(III) and As(V) in soils using sequential extraction combined with flow injection (FI) hydride generation atomic fluorescence spectrometry (HG-AFS) was presented. The soils were sequentially extracted by water, 0.6 mol l −1 KH 2PO 4 solution, 1% (v/v) HCl solution and 1% (w/v) NaOH solution. The arsenite (As(III)) in extract was analyzed by HG-AFS in the medium of 0.1 mol l −1 citric acid solution, then the total arsenic in extract was determined by HG-AFS using on-line reduction of arsenate with l-cysteine. The concentration of arsenate (As(V)) was calculated by the difference. The optimum conditions of extraction and determination were studied in detail. The detection limit (3 σ) for As(III) and As(V) were 0.11 and 0.07 μg l −1, respectively. The relative standard deviation (R.S.D.) was 1.43% ( n=11) at the 10 μg l −1 As level. The method was applied in the determination of As(III) and As(V) of real soils and the recoveries of As(III) and As(V) were in the range of 89.3–118 and 80.4–111%, respectively.

Determination of trace amounts of germanium by flow injection hydride generation atomic fluorescence spectrometry with on-line coprecipitation

A method for the determination of trace amounts of germanium by hydride generation atomic fluorescence spectrometry (HG-AFS) associated on-line with flow injection (FI) coprecipitation preconcentration was described. The samples, each spiked with Ni 2+ (500 μg ml −1), were introduced into the FI system using time-based injection, and mixed with a NaOH solution (50 g l −1). Germanium was preconcentrated by coprecipitation with the generated nickel hydroxide precipitate. The precipitate is subsequently eluted with 20% (v/v) phosphate acid solution and directed into the HG-AFS system. This method is simple and rapid. The detection limit (3 σ) was 0.11 μg l −1 and the relative standard deviation was 5.6% ( n=11) at the 10 μg l −1 level.

Completely integrated on-line determination of dissolved selenium(IV) and total inorganic selenium in sea-water by flow injection hydride generation atomic fluorescence spectrometry

Highly sensitive on-line pre-treatment methods were developed for the direct determination of trace amounts of selenite and total inorganic Se in sea-water. Selenite determination was carried out on samples acidified with HCl and merged on-line with 5% m/v KH2PO4, which was employed as an interference eliminating reagent. For total inorganic Se determination, acidified samples were merged with 30% m/v NaBr, used for reduction of Se(vi), and pre-reduced on-line by microwave irradiation at 210 W for 60 s. After pre-treatment, the sample zone was stored in a coil and then transported at a flow rate of 22 ml min –1 for reaction with 1.5% m/v NaBH 4 . The hydride produced was separated and dried and Se was determined in a mini-hydrogen diffusion flame by non-dispersive atomic fluorescence spectrometry. The interface developed for this purpose makes possible the integration, within the same manifold, of two steps involving very different reaction times. The detection limits were 5 ng l –1 for Se(iv) and 4 ng l –1 for total inorganic Se. The recoveries of selenite at the 30 ng l –1 level were 94-104% and those of total inorganic Se, at the same concentration level, were 92-98%. The methods developed are suitable for the accurate and direct analysis of natural waters, and the results obtained for total inorganic Se determination in a freshwater reference material were in good agreement with the certified value.