Cold Vapour Atomic Fluorescence Spectrophotometry Research Articles

Total mercury exposure through canned tuna in water sold in Quito, Ecuador.

Mercury is a toxic trace metal found in seafood products owing to its bioaccumulative and ubiquitous nature. Seafood and fish are frequently consumed, being necessary to assess its human health risk. Accordingly, this study quantified total mercury in samples of canned tuna in water from supermarkets in the Metropolitan District of Quito in Ecuador, in order to ensure that Hg content is within the maximum limits stablished in national and international regulations. Total mercury levels were measured through cold vapor atomic fluorescence spectrophotometry. Three of the most consumed tuna brands in Ecuador were analyzed, coded as A, B, and C, according to the price at which they are sold in the market (A < B < C). Results indicated that mean total mercury in different tuna brands were within the permissible limits. Total mercury concentrations were 0.14 ± 0.11mg kg-1; 0.41 ± 0.42mg kg-1; and 0.25 ± 0.22mg kg-1 for brands A, B, and C, respectively. However, for brand B the potential non-carcinogenic risk of mercury for consumers exceeded the threshold limit (> 1). When considering the highest total mercury content to which Ecuadorian population is exposed through the consumption of brand A, B, and C, the recommended weekly intake for children and adults were: A: 63g and 306g; B: 12g and 57g; C: 30g and 144g, respectively.

Bionanomaterial composed of Bradyrhizobium japonicum and graphene oxide for determination of mercury in water and fruit juice samples

In the present work, the synthesis of a novel hybrid bionanomaterial formed by the bacteria Bradyrhizobium japonicum (BJ) and the graphene oxide (GO) nanomaterial implemented in the miniaturized dispersive microsolid phase extraction technique (D-μ-SPE) was reported for the first time for the preconcentration and determination of Hg in water and fruit juice samples after a multivariate optimization. Selective Hg extraction was achieved by forming a complex with ammonium pyrrolidinedithiocarbamate (APDC) reagent and a multivariate study was performed to optimize the experimental conditions. The optimal Hg extraction conditions for 25 mL of sample were 3 mg of BJ@GO, NaNO3 at 1% (w/v), 6 min of vortex agitation and 9 min of centrifugation. For back extraction, 500 µL of 14 mol L−1 HNO3, 6 min of vortex agitation and 6 min of centrifugation were used followed by detection by cold vapor atomic fluorescence spectrophotometry (CV-AFS). Under optimized experimental conditions, an extraction efficiency of 98%, a detection limit of 0.08 µg L−1, a relative standard deviation of 3.5% (at 1 µg L−1 of Hg, n = 10), and a linear range of 0.26 - 4.0 µg L−1 were obtained. In addition, the sustainability of the method developed through the use of the Analytical GREEnness calculator (AGREE) software was evaluated, obtaining a greenness degree of 0.59. This work reports the first application of BJ@GO along with the D-μ-SPE technique for trace Hg determination water and fruit juice samples. In this way, this research work allows the exact and precise determination of low Hg concentrations in water and juice samples, which allows the evaluation of the contamination degree by this toxic metal in beverages widely consumed by the population.

Total mercury determination in bivalves Anadara tuberculosa sold in open markets from Quito, Ecuador

This study aimed to quantify the amount of total mercury in bivalves Anadara tuberculosa supplied from Esmeraldas Province and sold in markets in the Metropolitan District of Quito, Ecuador. The determined total mercury concentration was compared to the permissible limits established by the European Commission and World Health Organization-Food and Agriculture Organization and health risk subsequently assessed. Sampling was conducted in five open markets and involved collecting fifteen specimens from each market. Total mercury was measured through cold vapor atomic fluorescence spectrophotometry. Results showed that samples did not exceed the total mercury threshold value (0.5 mg kg−1). However, samples of Anadara tuberculosa from the Ofelia market, which receives fresh products from Eloy Alfaro canton, contained the highest mean levels of mercury contamination, 0.055 mg kg−1. This result could be associated to the influence of illegal mining activity in this area. In addition, methylmercury potential non-carcinogenic risk for consumers exceeded the threshold limit (>1) established by the US Environmental Protection Agency. The daily consumption rate (Rclim) was determined to be 26.61–38.50 g for a child weight of 14.5 kg, and 128.44–185.84 g for an adult weight of 70 kg. Thus, consuming a higher amount of Anadara tuberculosa could negatively affect human health.

Total mercury in hair as biomarker for methylmercury exposure among women in central Sweden- a 23 year long temporal trend study.

Exposure to methylmercury (MeHg) through fish is a global public health problem. Exposure monitoring is essential for health risk assessment, especially in pregnant women and children due to the documented neurotoxicity. Herein, we evaluate a time series of MeHg exposure via fish in primiparous Swedish women, covering a time period of 23 years (1996-2019). The 655 included mothers were part of the POPUP study (Persistent Organic Pollutants in Uppsala Primiparas) conducted by the Swedish Food Agency (SFA). MeHg exposure was assessed via measurements of total mercury (Hg) in hair using either cold vapor atomic fluorescence spectrophotometry or inductively coupled plasma mass spectrometry, showing very good linear agreement (R2=0.97). Maternal characteristics and fish consumption were obtained via questionnaires. The median concentration of total Hg in hair was 0.38mg/kg (range 0.17-1.5) in 1996 and 0.25mg/kg (range 0.03-1.1) in 2019. On average the women consumed 11±8.2 meals of fish per month, and fish consumption was positively correlated with total Hg in hair (Spearman correlation: 0.39; p<0.001). In multiple regression analyses, the geometric mean annual decrease of total Hg in hair was-2.5% (95% CI: -3.2,-1.8%). Total fish consumption increased up to 2011 (B: 0.32 times/month per year; 95% CI 0.17, 0.46) after which it started to decline (B: -0.66 times/month per year; 95% CI -0.92,-0.40). Moreover, both total Hg in hair and fish consumption was positively associated with maternal age and education, and inversely associated with pre-pregnancy BMI. In conclusion, the exposure to MeHg via fish appears to be slowly declining among Swedish pregnant women.

Optimization of a Digestion Method to Determine Total Mercury in Fish Tissue by Cold Vapor Atomic Fluorescence Spectrophotometry.

Several microwave-assisted digestion methods were tested at the Centro de Estudios Aplicados en Química laboratory in Quito, Ecuador, to determine the accuracy and performance efficiency of the mineralization process for the determination of total mercury in fish tissue by cold vapor atomic fluorescence spectrophotometry. The use of MARSEasyPrep high-pressure vessels, low amounts of reagents (1 cm3 HNO3, 1 cm3 H2O2, and 1 cm3 HClO4), an irradiation temperature of 210 °C, and 35 min of mineralization time resulted in accurate performance, with recoveries of certified reference material DORM-4 between 90.1% and 105.8%. This is better than the Association of Official Analytical Chemists 2015.01 method, which has a reported accuracy of 81%. The repeatability precision and intermediate precision were established at three concentration levels (0.167, 0.500, and 0.833 mg·kg−1) and expressed as the percentage of the relative standard deviation ranging from 1.5% to 3.0% and 1.7% to 4.2%, respectively. Further, the method was satisfactorily applied to analyze fortified samples of tilapia (Oreochromis niloticus), with recoveries ranging from 98.3% to 104.3%. The instrumental limits of detection and quantification were 0.118 µg·dm−3 and 0.394 µg·dm−3, respectively.

Portable smartphone-based device for on-site detection of Hg2+ in water samples

ABSTRACT In this paper, a smartphone-based portable device was designed for on-site and real-time detection of Hg2+ concentration levels in water samples. A rhodaminespirolactam-based derivative3ʹ,6ʹ-bis(diethylamino)-2-((3,4,5-trimethoxybenzylidene)amino)spiro[isoindoline-1,9ʹ-xanthen]-3-one, which had selective response to Hg2+,was used as Off-On fluorescent probe. The enhanced emission was observed by a high-pixel camera integrated on the smartphone. The grey value was analysed by an android/apple application ‘Detection’, and showed good linearly with Hg2+ concentration ranged from 0.01 to 0.1 μg/ml. The limit of detection (LODs) was found at 0.9 μg/l, which was sensitive enough to detect Hg2+ in industrial wastewater and drinking water. The accuracy of the proposed method was validated by reference Hg2+ solution, and the result was in good agreement with the certified value. Compared with cold vapour atomic fluorescence spectrophotometry, atomic absorption spectrophotometry methods and fluorescence method, etc., the developed platform is simpler, cost-less and portable for on-site and real-time application, and can be used for sharing of in-field sensing data from any remote location to the central water quality monitoring station.

Metal oxide nanoparticle-modified graphene oxide for removal of elemental mercury

ABSTRACTMercury is an extremely toxic element that is primarily released by anthropogenic activities and natural sources. Controlling Hg emissions, especially from coal combustion flue gas, is of practical importance in protecting the environment and preventing human health risks. In the present work, three metal oxides (MnO2, CuO, and ZnO) were loaded on graphene oxide (GO) sorbents (designated as MnO2-GO, CuO-GO, and ZnO-GO). All three adsorbents were successfully synthesized and were well characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results indicated that the metal oxide nanoparticles (NPs) successfully decorated the GO. The elemental Hg adsorption capabilities of the three sorbents were subsequently evaluated using an in-house built setup for cold vapour atomic fluorescence spectrophotometry (CVAFS) with argon as the carrier gas for mercury detection. The testing temperature ranged from 50°C to 200°C at intervals of 50°C. MnO2-GO showed an excel lent Hg0 adsorption capacity via chemisorption from 50 to 150°C and a mercury removal efficiency as high as 85% at 200°C, indicating that the MnO2-NP-modified GO is applicable for enhancing gas-phase elemental mercury removal. However, neither CuO-GO nor ZnO-GO performed well. This work provides useful insights into the development of novel sorbent materials for the elemental mercury removal from flue gases.

Analysis of Methylmercury Concentration in the Blood of Koreans by Using Cold Vapor Atomic Fluorescence Spectrophotometry

BackgroundMethylmercury is an organic form of mercury that is highly toxic to humans. Here, we present and establish a novel method to detect methylmercury concentrations in the blood of Koreans.MethodsMethylmercury concentration was analyzed with an automated methylmercury analytic system (MERX, Brooks Rand Co., USA) using cold vapor atomic fluorescence spectrophotometry (CVAFS). A variety of biological materials were digested in methanolic potassium hydroxide solution. The analysis method was validated by examination of certified reference material (955c, National Institute of Standard and Technology, USA). We randomly selected 30 Korean adults (age 20 yr or older) to analyze total blood mercury and methylmercury concentrations.ResultsThe detection limit and methylmercury recovery rate using this method were 0.1 pg/L and, 99.19% (range: 89.33-104.89%), respectively. The mean blood concentration of methylmercury was 4.54±2.15 µg/L (N=30). The mean proportion of methylmercury to the total mercury concentration was 78.27% (range: 41.37-98.80%).ConclusionsThis study is the first report to analyze blood methylmercury concentration using CVAFS in Korea. We expect that this method will contribute to the evaluation of mercury exposure and the assessment of the toxicological impact of mercury in future studies.

Coupling Laser Ablation and Atomic Fluorescence Spectrophotometry: An Example Using Mercury Analysis of Small Sections of Fish Scales

Mercury is a toxic element that exchanges among air, water, and sediments and biomagnifies into high trophic level organisms. Here, we present a novel combination of laser ablation with relatively low-cost cold vapor atomic fluorescence spectrophotometry to analyze Hg vaporized from targeted patches of fish scale 300-500 μm square. This method permits the analysis of multiple samples from the same scale, which is useful, because fish scale growth rings may provide an archive from which spatial and temporal trends in environmental Hg can be inferred at fine resolution. The detection limit of the method is 1.5 pg Hg, with a precision of 0.1 pg/μL. Developed using fish scales, the method could be adapted to other media, such as baleen, shells, nails, hair, teeth, wood and, possibly, varved sediments.

Carbon Nanotube-Silver Composite for Mercury Capture and Analysis

The carbon nanotube-silver composite (Ag-CNT) is a new class of multifunctional materials with potential applications such as sensors, catalysts, biodisinfection, and sorbents. A simple method combining wet-chemistry and thermal reduction was adopted to synthesize silver on the surface of the CNT. The synthesized Ag-CNT was tested as a sorbent for the removal of elemental mercury from flue gases of coal-fired power plants and as a mercury trap for elemental mercury analysis. A complete capture of mercury by the Ag-CNT was achieved up to a capture temperature of 150 °C, similar to the temperature of flue gases in coal-fired power plants. The captured mercury could be quickly and completely released by simple heating at 330 °C, to restore its mercury adsorption capacity. Silver on the Ag-CNT was shown to be the main active component for the mercury capture via an amalgamation mechanism in contrast to simple physical adsorption on the undoped CNT . Compared to silver-coated quartz beads (Ag-beads) and gold-coated quartz beads (Au-beads), which is conventionally used as a mercury trap for mercury measurements, the Ag-CNT showed a much higher mercury capture capacity and a minimal memory effect. With the Ag-CNT as a mercury preconcentration trap, calibration results showed a satisfactory linear coefficient of ≥0.9998 between known amounts of standard mercury and their corresponding fluorescence signals of cold vapor atomic fluorescence spectrophotometry (CVAFS). The presence of SO2, NOx, CO2, or O2 showed a negligible impact on the mercury capture performance of the Ag-CNT.

Mercury Concentrations in Gonad, Liver, and Muscle of White Sturgeon Acipenser transmontanus in the Lower Columbia River

This study determined the partitioning of total mercury in liver, gonad, and cheek muscle of white sturgeon (Acipenser transmonatus) in the lower Columbia River. The relationship between tissue mercury concentrations and various physiologic parameters was assessed. White sturgeon were captured in commercial fisheries in the estuary and Bonneville, The Dalles, and John Day Reservoirs. Condition factor (CF), relative weight (Wr), and gonadosomatic index (GSI) were determined for each fish (n = 57). Gonadal tissue was examined histologically to determine sex and stage of maturity. Liver (n = 49), gonad (n = 49), and cheek muscle (n = 57) were analyzed for total mercury using cold-vapor atomic fluorescence spectrophotometry. Tissue protein concentrations were measured by ultraviolet-visible spectroscopy. Plasma was analyzed for testosterone (T), 11-ketotestosterone (KT), and 17ss-estradiol (E2) using radioimmunoassay. Mean tissue mercury concentrations were higher in muscle compared with liver and gonad at all sampling locations, except Bonneville Reservoir where mean liver mercury content was the highest tissue concentration observed in the study. Significant negative correlations between plasma androgens (T and KT) and muscle mercury content and plasma E2 and liver mercury content were found. A significant positive linear relationship between white sturgeon age and liver mercury concentrations was evident. Significant negative correlations between CF and relative weight and gonad and liver mercury content were found. In addition, immature male sturgeon with increased gonad mercury content had decreased GSIs. These results suggest that mercury, in the form of methylmercury, may have an effect on the reproductive potential of white sturgeon.

Inter-individual variations of human mercury exposure biomarkers: a cross-sectional assessment

BackgroundBiomarkers for mercury (Hg) exposure have frequently been used to assess exposure and risk in various groups of the general population. We have evaluated the most frequently used biomarkers and the physiology on which they are based, to explore the inter-individual variations and their suitability for exposure assessment.MethodsConcentrations of total Hg (THg), inorganic Hg (IHg) and organic Hg (OHg, assumed to be methylmercury; MeHg) were determined in whole blood, red blood cells, plasma, hair and urine from Swedish men and women. An automated multiple injection cold vapour atomic fluorescence spectrophotometry analytical system for Hg analysis was developed, which provided high sensitivity, accuracy, and precision. The distribution of the various mercury forms in the different biological media was explored.ResultsAbout 90% of the mercury found in the red blood cells was in the form of MeHg with small inter-individual variations, and part of the IHg found in the red blood cells could be attributed to demethylated MeHg. THg in plasma was associated with both IHg and MeHg, with large inter-individual variations in the distribution between red blood cells and plasma. THg in hair reflects MeHg exposure at all exposure levels, and not IHg exposure. The small fraction of IHg in hair is most probably emanating from demethylated MeHg. The inter-individual variation in the blood to hair ratio was very large. The variability seemed to decrease with increasing OHg in blood, most probably due to more frequent fish consumption and thereby blood concentrations approaching steady state. THg in urine reflected IHg exposure, also at very low IHg exposure levels.ConclusionThe use of THg concentration in whole blood as a proxy for MeHg exposure will give rise to an overestimation of the MeHg exposure depending on the degree of IHg exposure, why speciation of mercury forms is needed. THg in RBC and hair are suitable proxies for MeHg exposure. Using THg concentration in plasma as a measure of IHg exposure can lead to significant exposure misclassification. THg in urine is a suitable proxy for IHg exposure.

Evaluation of Nonlethal Methods for the Analysis of Mercury in Fish Tissue

AbstractThousands of fish are sacrificed each year to determine potential human exposure to mercury (Hg) from fish consumption. In this paper, we use lake whitefish Coregonus clupeaformis and northern pike Esox lucius to demonstrate that accurate and reliable measures of fish muscle Hg concentrations can be determined from small samples (&lt;100 mg) harvested with biopsy tools. Reliability of results primarily depends upon analytical methodology and tissue sample weight. Mercury concentrations estimated by use of cold‐vapor atomic absorption spectrophotometry (CVAAS) on small composite tissue samples harvested with a Tru‐Cut (TC) biopsy needle (mean sample wet weight = 47 mg) were less precise than estimates from tissue samples harvested with a dermal punch (DP; mean sample wet weight = 126 mg). Precision differences presumably occurred because TC samples weighed less than the prescribed minimum weight (&gt;100 mg) for CVAAS. There was no difference in precision of Hg concentrations among tissue extraction methods when biopsy samples were analyzed via cold‐vapor atomic fluorescence spectrophotometry (CVAFS). Mean tissue Hg concentrations obtained with the biopsy techniques and CVAAS or CVAFS were similar to benchmark concentrations in fillet samples (within 6%), even for TC– CVAAS. A field study of the effects of the DP biopsy method on survival of northern pike showed that tissue harvesting did not reduce survival. Our results clearly demonstrate that analysis of Hg content in muscle harvested with biopsy tools provides Hg measures comparable in accuracy to traditional, whole‐fish methods but without causing mortality.

Inorganic mercury and methylmercury in placentas of Swedish women.

We determined levels of inorganic mercury (I-Hg) and methylmercury in placentas from 119 Swedish women, not selected with respect to high exposure of mercury. Our objective was to relate placental Hg species with maternal and fetal blood concentrations and to evaluate possible associations with selenium. We performed the analyses using automated alkaline solubilization/reduction and cold-vapor atomic fluorescence spectrophotometry. I-Hg levels in placenta increased with an increasing number of maternal dental amalgam fillings (p < 0.001). Despite placental accumulation (median, 1.3 microg/kg; range, 0.18-6.7 microg/kg wet weight), a substantial fraction of maternal blood I-Hg, probably as Hg(0), reached the fetus. Although MeHg transferred easily to the fetus, it also accumulated in the placenta. On average, 60% of placental Hg was in the form of MeHg. The median concentration was 1.8 microg/kg (range, 0-6.2 microg/kg wet weight), more than twice the maternal blood concentration. We found significant associations between MeHg and selenium in both maternal and umbilical cord blood but not in the placenta. The associations were particularly obvious in freshwater fish consumers, probably reflecting that fish is a source of both MeHg and selenium. We found no correlations between I-Hg and selenium. This study increases the understanding of Hg, in its different forms, in human placenta and how they are related to maternal and fetal exposure.

Determination of mercury in air by adsorption on Hopcalite and by neutron activation analysis

A new method for the determination of mercury in air has been developed. It combines the adsorption of mercury on Hopcalite (a material approved for this purpose by the National Institute of Health of the United States) and its quantification by neutron activation. The concentrations of mercury in office air in Montreal, Canada, were determined by instrumental semiabsolute neutron activation analysis. They varied from 39 to 48 ng/m 3 . The results were compared with the concentrations of mercury in office air determined simultaneously at the same place by cold vapour atomic fluorescence spectrophotometry. A close correlation between the results of the 2 methods was obtained. The detection limit of our method is about 14 ng/m 3 .

Mercury concentrations in single event precipitation in southern Québec

The paper presents one year of results (1995–1996) of an on-going research study in southern Québec with regard to mercury in precipitation. A modified rain water collector (MIC-B1) coupled to a data logger is used, in order to be able to select individual events from a remote site. A peristaltic pump coupled with an enclosed Teflon system train separates `in situ' the particulate and the dissolved phases of mercury. QA/QC sampling protocol including memory effect, percentage of recovery as well as field blanks are applied to maintain the high standards of quality. Total mercury concentrations in both phases are measured by Cold Vapour Atomic Fluorescence Spectrophotometry (CVAFS). The volume-weighted mean of total Hg concentration is 6.98 ng.l −1 (the median concentration is 6.58 ng.l −1 and the arithmetic mean is 8.26 ng.l −1). The annual total mercury deposition is about 7.6 μg.m −2. The particulate fraction accounts for a median of 26% of the total mercury concentration. According to Henry's Law, the truly dissolved mercury accounts for less than 0.5% whereas most of the dissolved fraction is expected to be in molecular complexes or colloidal form (<0.45 μm). A decreasing Hg concentration trend is observed with precipitation amount for both dissolved and particulate phases. Variability in the concentration and deposition ranges suggests complex chemical and scavenging processes.