Atomic Fluorescence Spectrometry Research Articles

Atomic spectrometry update – a review of advances in environmental analysis

This review covers advances in the analysis of air, water, plants, soils and geological materials by a range of atomic spectrometric techniques including atomic emission, absorption, fluorescence and mass spectrometry.

Atomic spectrometry update: review of advances in atomic spectrometry and related techniques

This review covers advances in atomic spectrometric techniques, including atomic emission, absorption, fluorescence and mass spectrometry. Material on speciation and coupled techniques is not covered as this is included in a separate ASU review.

Mercury Concentration in Liver Tissues of South American Fur Seals (Arctocephalus australis) from Southwestern Atlantic Ocean

Mercury (Hg) contamination of oceans is rapidly increasing, however Hg bioaccumulation in pinnipeds has been understudied. Here, we report for the first time Hg concentration in liver tissues of South American fur seals (Arctocephalus australis) in South and Southeast Brazil. Hg concentration was determined in twenty-five fur seals’ specimens found stranded along the coast of the Southwestern Atlantic Ocean. Samples were digested using the microwave technique and quantified by cold vapor generation atomic fluorescence spectrometry technique. The average Hg concentration was 6.37 mg kg-1 (wet weight), with a minimum concentration of 0.09 mg kg-1 and the highest concentration of 15.58 mg kg-1. No correlation between biological variables (sex, total length and weight) and Hg concentration in A. australis liver were found. The results presented here are of great importance to establish baselines for future evaluations of Hg contamination in marine mammals and the effects of this environmental problem in animal health.

Multi-Commutated Flow System for Inorganic Selenium Speciation in Infusion Tea Samples by Hydride Generation Atomic Fluorescence Spectrometry

Multi-Commutated Flow System for Inorganic Selenium Speciation in Infusion Tea Samples by Hydride Generation Atomic Fluorescence Spectrometry

Analysis and suppression of scattering interference for arsenic using dispersive atomic fluorescence spectrometry based on an ultraviolet digital micromirror device spectrometer

A combination of UV-DMD-AFS and NFLR methods has been successfully used in the real-time suppression of scattering interference for arsenic, achieving long-term accuracy >99.20% (within 3 hours) in water quality samples.

Sulfur-doped reduced graphene oxide@chitosan composite for the selective and sensitive electrochemical detection of Hg2+ in fish muscle

In this study, a glassy carbon electrode was modified with sulfur-doped reduced graphene oxide (S-rGO) and then combined with chitosan (CTS) to produce an electrochemical sensor. There is a favorable interaction between Hg2+ and S-rGO, due to the strong affinity between sulfur and mercury. This effect was exploited for the selective and sensitive electrochemical determination of trace amounts of Hg2+ in fish muscle samples by differential pulse anodic stripping voltammetry (DPASV). The factors that can affect the sensitivity and precision of the modified electrode were investigated through the optimization of various parameters, such as S-rGO concentration, solution pH, deposition potential, accumulation potential, accumulation time, and supporting electrolytes. By introducing S-rGO to enrich and amplify the electrochemical signal, the sensing strategy allowed to detect a range from 0.125 to 6 μM Hg2+ with a detection limit of 1.6 nM. The sensor also showed excellent selectivity towards Hg2+ in the presence of interfering metal ions, such as Fe3+, Zn2+, Mg2+, Mn2+, As3+, Na+, Cd2+ and CO2+. The practical feasibility of the proposed sensor was assessed in fish muscle samples with satisfactory results compared with that of atomic fluorescence spectrometry. Moreover, this work demonstrated a simple and reliable method for improving the electrochemical performance of Hg2+ sensor, which paves the way for many promising potential applications in the field of environmental testing.

Therapeutic Effect of Seawater Pearl Powder on UV-Induced Photoaging in Mouse Skin.

The objective of this study was to investigate the therapeutic effect of seawater pearl powder (SPP) on ultraviolet (UV) irradiation-induced photoaging in mouse skin. The protein and trace elements in SPP were detected by liquid chromatography-mass spectrometry, atomic fluorescence spectrometry, and inductively coupled plasma-atomic emission spectrometry. The effect of SPP on treating skin damage resulting from UV-induced photoaging was observed by gross physical appearance and histopathological analysis. Oxidative stress and melanin synthesis were analyzed using biochemical method. Western blotting was applied to analyze the phosphorylation and expression levels of matrix metalloproteinase-1 (MMP-1), collagen I, and proteins involved in the mitogen-activated protein kinase (MAPK) signaling pathways (p38, ERK, and JNK). The results show that SPP has a significant therapeutic effect on UV-induced photoaging of skin and improves and restores appearance and tissue structure of mouse skin. The major mechanism may be related to reduction of expression level of MMP-1 and enhancement of collagen I production via inhibition of MAPK signaling pathway after scavenging of excess reactive oxygen species (ROS) in the UV-induced photoaged skin of mice. Meanwhile, it may also be involved in reducing melanin content by inhibiting tyrosinase activity after scavenging excess ROS in the UV-induced photoaged skin of mice. Therefore, SPP could be a good substance to treat photoaging skin. Taking cost-effectiveness and efficacy into consideration, the optimal concentration of SPP for treating photoaging skin could be 100 mg/g.

Highly sensitive determination of trace antimony in water samples by cobalt ion enhanced photochemical vapor generation coupled with atomic fluorescence spectrometry or ICP-MS

A method for highly sensitive determination of trace antimony was proposed by using cobalt ion enhanced photochemical vapor generation (PCVG) for sample introduction into atomic fluorescence spectrometry (AFS) or inductively coupled plasma-mass spectrometry (ICP-MS) for elemental detection. During the PCVG process, the sample introduction efficiency of Sb could be significantly improved by addition of 5 mg L−1 Co2+ in the mixed acid medium of 10% (v/v) formic acid and 20% (v/v) acetic acid, with a final 12-fold and 133-fold enhancement of AFS and ICP-MS intensity, respectively. The experimental conditions including enhancement ions, acid medium, UV irradiation, working gas as well as potential interference were investigated in detail. Under the optimal experimental conditions, the limit of detection (LOD) for Sb was 0.05 and 0.001 μg L−1 by using AFS and ICP-MS determination, respectively. The method was successfully used for analysis of real water samples, with satisfactory recoveries of 92–94%.

Effect of dietary selenium intake on gut microbiota in older population in Enshi region

BackgroundThe microbial ecosystem in the human gut varies between individuals with differences in diet. Selenium is one of most common trace elements in everyday diet, and selenium intake affects the human gut microbiota. We studied the effect of selenium intake on the gut microbiota in regions of Enshi with different distributions of selenium.MethodsOne hundred elderly subjects (>65 years) were recruited from high-selenium and low-selenium areas in Enshi and blood, nail, and fecal specimens were obtained. The selenium contents in these samples were determined in triplicate by hydride generation atomic fluorescence spectrometry. DNA was extracted from fecal specimens and the microbial diversity was analyzed by 16 S RNA.ResultsThe selenium contents in the blood and nails were significantly different between the high- and low-selenium areas, and the composition of the intestinal microbiota, including abundance and extent of intestinal flora, was altered. The function and metabolic pathways of the gut microbiota showed clear differences.ConclusionsAs a trace element in human diet, selenium intake is an important factor that affects the intestinal microbiota and is likely involved in many human diseases. This study provides new clues and ideas for studying the correlation between selenium and human health.

The Occurrence, Pathways, and Risk Assessment of Heavy Metals in Raw Milk from Industrial Areas in China.

This study evaluated chromium (Cr), arsenic (As), cadmium (Cd), and lead (Pb) contamination in raw milk from industrial areas in China, identified the possible pathways of heavy metals from the environment to raw milk, and made a risk assessment of the consumption of heavy metals from milk consumption. The Cr, As, Cd, and Pb concentrations in raw milk, water and silage were analyzed using inductively coupled plasma mass spectrometry. The Cr and As in soil were analyzed by flame atomic absorption spectrometry and atomic fluorescence spectrometry, respectively. Cd and Pb in soil were determined by a Graphite furnace atomic absorption spectrophotometer. The Cr and As concentrations in milk from industrial areas were 2.41 ± 2.12 and 0.44 ± 0.31 μg/kg, respectively, which were significantly higher (p < 0.01) than those from non-industrial areas, which had levels of 1.10 ± 0.15 and 0.25 ± 0.09 μg/kg, respectively. Chromium was mainly transferred through the soil-silage-milk pathway, As was transferred through the water-silage-milk pathway, while Cd was mainly transferred through the soil (water)-silage-milk pathway. The contributions of each metal to the overall hazard index (HI) followed a descending order of As, Cr, Pb, and Cd, with values of 46.64%, 25.54%, 24.30%, and 3.52%, respectively. Children were at higher risk than adults.

Estimating the spatial distribution of soil total arsenic in the suspected contaminated area using UAV-Borne hyperspectral imagery and deep learning

The total arsenic (TAs) content in the soil is commonly used as an important indicator for evaluating soil pollution. However, the traditional methods for investigating TAs concentration in soil over a large area are always labor-intensive and costly. As a rapid and convenient technique, unmanned aerial vehicle (UAV) equipped with hyperspectral camera offers a promising way for estimating the distribution of TAs. In this study, we utilized UAV-borne hyperspectral data over the Daye city of China mining suspected contaminated area to establish the deep model for retrieval of TAs. Specifically, 74 soil samples were collected in situ from the study area, and their TAs contents were measured by using atomic fluorescence spectrometry(AFS). Meanwhile, use UAV captured hyperspectral imagery of the study area. We propose a novel method which deep neural networks with competitive adaptive reweighted sampling (DNN-CARS) for the estimation of soil TAs content and the spatial distribution. For two testing areas, the values of R2 are 0.90 and 0.87, and the value of RMSE are 0.33 and 0.52. Experiments demonstrated, that UAV hyperspectral imagery combined with DNN-CARS is an effective tool for the evaluation of TAs content and mapping its spatial distribution.

A software system for dispersive atomic fluorescence spectrometry based on UV digital micromirror device.

A dispersive atomic fluorescence spectrometer based on a UV digital micromirror device (UV-DMD-AFS) has been proposed by our team for attenuating spectral and scattering interferences. Software is nontrivial for the automation of component control and sample analysis in the new instrument. In this work, the software was developed using the C# programming language together with multi-threading and combined with the SQLite database, which consists of component control and data acquisition, database, wavelength initialization, and real-time interference reduction module. To realize the accurate analysis of the trace heavy metal concentration, the spectral interference was avoided by measuring the non-interference wavelength, and the scattering interference was eliminated by the real-time proportional coefficient method. The microsecond rotation speed of the DMD is the key to achieving real-time reduction. The concentration of arsenic in Water Quality (GSB 07-3171-2014) was detected to validate the practicability of the software with the concentration deviation of 0.02 ng/mL.

Comparison of Uncertainty Evaluation for the Determination of Mercury Content in Dictyophora by Automatic Mercury Analyzer and Atomic Fluorescence Spectrometer

The content of mercury in Dictyophora was determined by automatic mercury analyzer and atomic fluorescence spectrometer. The main sources of uncertainty were analyzed and the main uncertainty components were calculated by establishing mathematical model, and the synthetic uncertainty and extended uncertainty were obtained, and the uncertainties results were compared. Results showed that, the expanded uncertainties of these two methods were 0.006 and 0.002 mg/kg (k=2), when the determination results of mercury were 0.050 mg/kg.This study might provide a guideline for uncertainty evaluation for determining mercury in edible fungus by automatic mercury analyzer and atomic fluorescence spectrometry.

Removal of high-concentration of arsenic in acidic wastewater through zero-valent aluminium powder and characterisation of products

Untreated arsenic in acidic wastewater causes serious environmental pollution. Zero-valent aluminium (ZVAl), without pretreatment, was used in this study to remove arsenic from acidic wastewater. We demonstrated that ZVAl could remove arsenic from acidic wastewater in 30 min with over 99% efficiency. Inductively coupled plasma mass spectrometry (ICP-MS) and hydride-generation atomic fluorescence spectrometry (HG-AFS) were employed to determine the change in ion concentration in acidic wastewater before and after the experiment. The success of using ZVAl for removing arsenic from acidic wastewater was investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TG). Characterisation of the precipitate after the reaction revealed that arsenic removal took place through a complex process which included reduction, surface corrosion, adsorption, co-precipitation, and chemical reactions to form precipitates. These results indicated that ZVAl is a promising material to efficiently remove arsenic from acidic wastewater in an environment friendly manner. The findings of this study will help to develop ZVAl as a method for treating arsenic-contaminated acidic wastewater.

Behavior of KCl sorbent traps and KCl trapping solutions used for atmospheric mercury speciation: stability and specificity

Abstract. Atmospheric mercury speciation is of paramount importance for understanding the behavior of mercury once it is emitted into the atmosphere as gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and particulate-bound mercury (PBM). GOM and PBM can also be formed in the atmosphere; their sampling is the most problematic step in the atmospheric mercury speciation. GOM sampling with speciation traps composed of KCl sorbent materials and KCl trapping solutions are commonly used sampling methods, although the research conducted with them at ambient air concentrations is limited. The results of the specificity test demonstrated that the KCl sorbent traps are highly specific when using new traps, while their specificity drops dramatically when they are reused. The results of the stability test indicated that the highest Hg2+ losses (up to 5.5 % of Hg2+ loss) occur when low amounts of Hg2+ (&lt; 1 ng) are loaded, due to a reduction of Hg2+ to Hg0. KCl trapping solutions have also been considered as a selective trapping media for GOM in atmospheric samples. A dimensionless Henry law constant was experimentally derived and was used to calculate the solubility of elemental Hg in KCl solution. The degree of GEM oxidation was established by purging elemental Hg calibration gas into a KCl solution and determining the GOM trapped using aqueous-phase propylation liquid–liquid extraction and gas chromatography–atomic fluorescence spectrometry (GC-AFS) measurement. A positive GOM bias was observed due to the solubility and oxidation of GEM in KCl trapping solutions, strongly suggesting that this approach is unsuitable for atmospheric mercury speciation measurements.

Arsenic contamination caused by roxarsone transformation with spatiotemporal variation of microbial community structure in a column experiment

Arsenic contamination from roxarsone in livestock manure is common, and livestock manure continuously accumulates in the open environment. Evaluations of the environmental processes of As mobilization and transformation are critical for predicting the fate of As compounds after roxarsone degradation. In this study, spatiotemporal variations in As species and microbial community structure were characterized using laboratory column experiments with background soil collected from Yanggu County (northern Shandong Plain, China), a region of intense poultry production. Organic and inorganic arsenic were detected by high-performance liquid chromatography (HPLC) and HPLC with hydride generation atomic fluorescence spectrometry (HPLC-HG-AFS), respectively. High-throughput sequencing technology was used to describe microbial diversity. Results showed that roxarsone was transformed completely within 7 days, and As(Ⅲ) and As(Ⅴ) were the major degradation products. The concentration of As(Ⅲ) was much lower than that of As(Ⅴ). The As(Ⅲ) concentration increased significantly after Day 14, whereas the As(Ⅴ) concentration increased significantly after Day 84, indicating that As(Ⅲ) was initially produced. The microbial community structure changed significantly as roxarsone transformed into various As compounds. A critical and dominant bacterial strain, norank_f__Family_XVⅢ, was found to be related to the degradation of roxarsone into As(Ⅲ). This study improves our understanding of the fate of As species released from poultry litter to soil and groundwater, which is a threat to human health and environment.

A label-free and enzyme-free fluorescent assay for mercury ions based on T-Hg(II)-T nanoladders and DNA-templated silver nanoclusters/graphene oxide nanocomposites

A label-free and enzyme-free signal-on biosensor for Hg(II) ions was constructed based on T-Hg(II)-T nanoladders and fluorescent DNA-templated silver nanoclusters/graphene oxide nanocomposites (DNA-AgNCs/GO). The T-rich sequences (P1 and P2) were used to capture Hg(II) and form the T-Hg(II)-T nanoladders. C6G5C6 was extended at the 5′ end of P1, used as a template for synthesizing fluorescent DNA-AgNCs. In the presence of mercury ions, the T-Hg(II)-T nanoladders significantly enhanced the emission of AgNCs. GO can attract free P1-C6G5C6 and P2 that were not involved in the formation of T-Hg(II)-T nanoladders, thus employed as the energy acceptor to quench the background fluorescence of AgNCs. The fluorescence enhancement induced by mercury ions can be used for quantitative detection of Hg(II) over the range 0.1–30 nM with a detection limit as low as 7.35 pM. This method was used to detect Hg(II) in the spiked samples of Songhua River water and grass carp, with the recoveries of 97.61%− 103.79% and 96.52%− 105.58% respectively, consistent with the results from atomic fluorescence spectrometry. Obviously, in this assay, enzyme-free signal amplification and signal identification are integrated in the ingenious design of nucleic acid sequences, thus achieving the label-free fluorescence detection of mercury ions.

Field determination of inorganic mercury in seawaters by a portable dual-channel and purge-and-trap system with atomic fluorescence spectrometry

ABSTRACT An on-line flow injection mercury analyser (FIMA) for inorganic mercury (Hg) analysis in environmental waters is presented. The FIMA is a portable dual-channel and purge-and-trap system combining aqueous reduction with stannous chloride (SnCl2), two-stage gold (Au) amalgamation, thermal desorption of Hg0 and final detection with cold vapour atomic fluorescence spectrometry (CVAFS). Simultaneous on-line operations of sample loading and analysis make analytical throughput and accuracy improved and contamination eliminated. Results of system optimisation and reliability regarding the determination of inorganic Hg2+ are described. Analytical performances of both channels were the same in terms of data reliability. Low procedural blanks were obtained from laboratory and field trip (≤5 pg, n = 30). Excellent calibrations (r2 > 0.99) with a high precision and good stability (RSD <5%, n = 30) were obtained. Detection limits and reproducibility of the methods have been estimated as ≤0.05 ng L−1 and <5% (0.5 ng L−1, n = 30). The system was finally validated by measurements comparison of the two channels (r2 > 0.98), and analysis of a certified reference material (coastal seawater BCR-579, recoveries 101 ± 4%, n = 10). Overall, a sample throughput of ~10 samples per hour with two-channel detections of FIMA can be achieved. The onboard analysis of inorganic Hg species (e.g. elemental, reactive, and total Hg) in surface seawaters of the East China Sea (ECS) are also successfully achieved. The portable FIMA is fast, easy, and robust for reliable monitoring of Hg in natural seawaters.

Pollution status and exposure assessment of lead, cadmium, total mercury and total arsenic in grains on sale from Shaanxi Province, 2002-2018

To investigate the pollution status of lead, cadmium, total mercury and total arsenic in grains sold in Shaanxi Province, and to analyze the potential risk of dietary exposure. A total of 1873 samples of wheat, wheat flour, rice, maize and their products were randomly collected in circulation. The contents of lead and cadmium were determined by atomic absorption spectrophotometry and inductively coupled plasma mass spectrometry, and total mercury and arsenic were determined by atomic fluorescence spectrometry. The pollution status of four elements in grains was evaluated by single factor pollution index method, margin of exposure(MOE) was used to assess lead exposure, cadmium exposure was assessed by the ratio of estimated monthly intake(EMI) to provisional tolerable monthly intake(PTMI), and exposure to mercury and arsenic was assessed using the ratio of estimated weekly intake(EWI) to provisional tolerable weekly intake(PTWI). The average values of lead, cadmium, total mercury and total arsenic in grains sold in Shaanxi Province were 0.070, 0.022, 0.0079 and 0.030 mg/kg. The over-standard rates of lead, cadmium and total mercury were 6.30%, 1.39% and 4.43%. The average single factor pollution index of lead, cadmium, total mercury and total arsenic was less than 0.7; The MOE value of lead in grains was 0.99-18.41, the intake of cadmium in grains accounted for 19.08% of PTMI, and the intake of mercury and arsenic accounted for 10.28% and 10.67% of PTWI. Lead, cadmium, total mercury and total arsenic in all kinds of cereals sold in Shaanxi Province from 2002 to 2018 were less polluted and their intake was within the safe range.

Sub-chronic exposure to realgar induces liver injury via upregulating the TXNIP/NLRP3 pathway and disturbing bile acid homeostasis in mice

Ethnopharmacological relevanceRealgar is a traditional Chinese medicine used in China for a long history. Long-time or excessive use of realgar causes liver injury. However, its underlying mechanism is not fully clarified. Aim of the studyIn this study, we investigated the toxic effect of sub-chronic exposure to realgar on mice liver, and further revealed its underlying mechanism focused on the TXNIP/NLRP3 pathway and bile acid homeostasis. Material and methodsMice were divided into control and different doses of sub-chronic realgar exposed groups. Total arsenic levels in the blood and liver were determined by atomic fluorescence spectrometry. The effect of realgar on liver function was evaluated by biochemical analysis and histopathological examination. Assay kits were applied for the measurement of oxidative stress indexes, MPO and plasma inflammatory cytokines. The mRNA and proteins involved in the TXNIP/NLRP3 and NF-κB pathways were determined by RT-qPCR, western blot, Immunofluorescence and Immunohistochemistry. UHPLC/MS/MS was used for the quantitative analysis of bile acids (BAs) in mice plasma, liver and urine. The genes related to BAs metabolism were measured by RT-qPCR. ResultsSub-chronic exposure to realgar led to arsenic accumulation and caused oxidative damage and inflammatory infiltration in mouse liver, finally resulting in liver injury. Realgar treatment activated the NF-κB pathway and significantly upregulated the TXNIP/NLRP3 pathway in mouse liver. Realgar altered the metabolic balance of BAs, which is related to the abnormal expression of BAs transporters and enzymes. ConclusionSub-chronic exposure to realgar caused liver injury in mouse, and the mechanism may involve the upregulation of the TXNIP/NLRP3 pathway and disordered BAs homeostasis.