Distribution of arsenic species in the freshwater crustacean Procambarus clarkii

The concentrations of total arsenic and arsenic species in the complete organism of the crayfish Procambarus clarkii and its various parts (hepatopancreas, tail, and remaining parts) were analyzed in order to discover the distribution of arsenic and its species. With this information it will be possible to establish where the chemical forms of this metalloid tend to accumulate and what risks may derive from the contents and species present in the edible parts of this crustacean. The total arsenic content in the complete organism and in the various parts analyzed ranged from 2.5 to 12 µg g^?1 dry mass (DM), with inorganic arsenic representing 18 to 34% of total arsenic. The arsenical composition varied according to the part of the crayfish considered. The hepatopancreas had the highest levels of total arsenic (9.2–12 µg g^?1 DM) and inorganic arsenic (2.7–3.2 µg g^?1 DM). The tail (edible part) had the lowest levels of both total arsenic (2.5–2.6 µg g^?1 DM) and inorganic arsenic (0.46–0.64 µg g^?1 DM). The predominant organoarsenical species were the dimethylarsinoylribosides: glycerol riboside in the hepatopancreas, sulfate riboside in the tail, and sulfonate and phosphate ribosides in the remaining parts. Copyright © 2002 John Wiley & Sons, Ltd.     

Differential pulse polarographic behaviour of thiazopyr herbicide and application to its determination in fruit juice and soil samples

A differential pulse polarographic method for the determination of the herbicide thiazopyr has been developed. The polarographic study of thiazopyr exhibited two well-defined cathodic peaks within the pH range of 1.0 to 8.0. The variation of pH and polarographic parameters indicated that the optimum conditions under which thiazopyr could be reduced were a pH 7.0 BR buffer solution, a reduction peak potential of ?1270 mV (vs. SCE), scan rate of 5 mV s^?1, pulse amplitude of 50 mV with pulse duration of 50 ms at an ambient temperature of 25 ± 3°C. The main reduction peak was characterised by cyclic voltammetry as being irreversible and diffusion-controlled. A linear relationship between the peak current and the concentration of thiazopyr was obtained in the range of 0.43–38.6 µg mL^?1, with a detection limit of 0.127 µg mL^?1. The proposed method was successfully applied to the determination of thiazopyr in spiked fruit juice and soil samples. The mean recoveries of the 19.8 µg g^?1 and 3.96 µg mL^?1 thiazopyr spiked to soil and orange juice were 20.2 ± 1.0 µg g^?1 and 3.84 ± 0.12 µg mL^?1, at 95% confidence level, respectively. The sufficiently good recoveries and low relative standard deviation (RSD) data confirm the high accuracy and precision of the proposed method. The interferences effects of several commonly used pesticides and inorganic species were also studied. Interfering effects were eliminated either by providing selectivity with pH, or using EDTA as complexing agent.     

Observations on toxicologically relevant arsenic in urine in adult offspring of families with Balkan Endemic Nephropathy and controls by batch hydride generation atomic absorption spectrometry

The aim of this study was to develop a method for the characterization of internal exposure to arsenic, which is thought to play a role in the development of a kidney disease, known as Balkan Endemic Nephropathy, typical for a district in Bulgaria, and to investigate whether the As body burden differs in the offspring versus control individuals. For this case study, an analytical procedure for the determination of toxicologically relevant arsenic (the sum of arsenite, arsenate, monomethylarsonate, and dimethylarsinate) in urine by batch-type hydride generation atomic absorption spectrometry was developed. Optimization experiments for levelling off the sensitivity of inorganic arsenic and its mono- and dimethylated species in dilute HCl–L-cysteine medium were performed. The limit of detection for hydride forming arsenic fraction was 0.5?ng As, i.e. 0.25?µg?L^?1 in 10?mL of 1?+?4 v/v diluted urine. The relative standard deviation was typically 1.5–1.8% for aqueous solution and 2–6% for urine samples at 1.0?µg?L^?1 As. The sample throughput rate was 15?h^?1. No statistical correlation and cross-correlation between individuals case-control and sex at 95% confidence were found: controls (n?=?99), mean 3.5?±?2.1 (SD), range 0.9–10.4, median 3.0?µg?L^?1 As and cases (n?=?102), mean 3.6?±?2.2 (SD), range 0.5–11.0, median 3.2?µg?L^?1 As. On the basis of this study, arsenic can be excluded as a factor involved in BEN development.     

Elemental Analysis of Tarhana by Microwave Induced Plasma Atomic Emission Spectrometry

Elemental analysis of tarhana, a traditional Turkish cereal soup, has been conducted. A new method was developed for the determination of calcium, iron, magnesium, manganese, potassium, and sodium, in tarhana by microwave induced plasma atomic emission spectrometry. A sample of 0.1?g were mineralized by microwave digestion in 10?mL of 65% HNO₃. A wheat flour standard reference material (GBW 08503) was used for validation. Linear calibration using standards prepared in acid was conducted for all determinations. The limits of detection were 1.21?µg?g^?1 for Ca at 393.366?nm, 0.43?µg?g^?1 for Fe at 259.940?nm, 11.5?µg?g^?1 for K at 766.491?nm, 0.12?µg?g^?1 for Mg at 285.213?nm, 0.04?µg?g^?1 for Mn at 403.076?nm, and 0.04?µg?g^?1 for Na at 588.995?nm. Ca, K, Fe, Mg, Mn, and Na were determined in tarhana with values from 0.73 to 1.61, 0.016 to 0.061, 2.02 to 4.09, 0.473 to 1.414, 0.019 to 0.043, and 0.26 to 1.83?mg?g^?1, respectively.     

Determination of arsenic by hydride generation with a long absorption cell for atomic absorption spectrometry

A method is described for the determination of arsenic involving hydride generation and atomic absorption spectrometry with an improved long graphite-tube furnace capable of considerably higher temperatures than the conventional quartz-tube heaters. Arsine is generated with sodium tetrahydroborate, held in a nitrogen-cooled trap and then swept with helium into an alumina tube (19 cm long) placed within the graphite furnace. The optimum conditions for determination of arsenic are given. The detection limit is 0.2 ng ml^?1 with RSD of 2–3%. Results for various NBS Standard Reference Materials agreed well with expected values and were as follows: orchard leaves, 10 ± 1 μg g^?1; tomato leaves, 0.28 ± 0.03 μg g^?1; bovine liver, 0.046 ± 0.005 μg g^?1.     

Profiling bioactive flavonoids and carotenoids in select south Indian spices and nuts

Abstract

The objective of this study was to examine the bioactive flavonoids and carotenoids concentration in fifteen south Indian spice and two tree nut species using high performance liquid chromatography (HPLC). Among four flavonoids, catechin concentration was the highest in all spices and nuts and ranged between 97.1 and 1745.4 µg g^?1. Quercetin concentration was the greatest in cinnamon, followed by garlic and cumin and ranged from 0.4 to 65 µg g^?1 in other spices and nuts. Lutein concentration ranged from 0.1 to 102.8 µg g^?1. Of the spices and nuts studied, β-carotene concentration was highest in coriander leaves (74.7 µg g^?1), followed by red pepper (12.5 µg g^?1) and curry leaves (8.5 µg g^?1). This research shows that consumption of south Indian spices and nuts could substantially benefit consumers living in regions experiencing Vitamin A and other micronutrient deficiencies.     

Determination of Heavy Metal Content in Wild-Edible Mushroom from Jordan

The heavy metal content was investigated for six mushroom species native to Jordan. Metal (Cu, Pb, Cd, Fe, Zn, Mn, Ni, and Co) content in soil substrate and their relation to metal concentrations in mushroom and underlying soil were determined by flame and graphite furnace atomic absorption spectrometry. Mushroom species and soil were collected from different places in Jordan. The highest Cu level was 51.84 µg g^?1 for the species Lepista nuda; whereas, the lowest Cu level was found to be 18.51 µg g^?1 in Calvatia utriformis. Among the wild mushrooms, the highest Pb level was found as 4.81 µg g^?1 in Bovista plumbea, whereas the lowest Pb concentration was 2.01 µg g^?1 in Calvatia utriformis. The highest Cd level was determined as 1.9 µg g^?1 for Lepista nuda, whereas the lowest Cd level was 0.58 µg g^?1 for the species of Polyporus frondosus. The highest Zn level was 58.77 µg g^?1 for the species of Lepista nuda and the lowest Zn concentration was found 35.98 µg g^?1 in Calvatia utriformis. The highest Fe level was found as 317 µg g^?1 in Lepista nuda, whereas the lowest Fe concentration was 211.7 µg g^?1 in Calvatia utriformis. The highest Mn content was 36.55 µg g^?1 for Russula delica, whereas the lowest Mn level was 24.5 µg g^?1 for the species Bovista plumbea. The highest Ni content was found as 12.65 µg g^?1 for Russula delica, whereas the lowest Ni level was 0.17 µg g^?1 for Bovista plumbea. The highest Co content in the tested mushrooms was found as 3.5 µg g^?1 for the species of Agaricus bisporus, whereas the lowest Co level was 0.85 µg g^?1 for Polyporus frondosus. The results indicated that, in general, heavy metal contents in all mushroom species were lower than the underlying soil substrates except for some mushroom species.     

Pressurised fluid extraction of polycyclic aromatic hydrocarbons and their polar oxidation products from atmospheric particles

An effective method utilising pressurised fluid extraction (PFE) to simultaneously extract polycyclic aromatic hydrocarbons (PAHs) and their polar oxidation products from atmospheric particulate matter (PM) is presented. The PFE method is advantageous over the traditional Soxhlet extraction due to its lower solvent consumption (9 mL compared to 90 mL) and shorter extraction time (15 min versus 18 h). Seventy compounds including PAHs and polar PAH oxidation products containing carbonyl (oxy-PAHs), hydroxyl (hydroxy-PAHs), and carboxylic acid (carboxy-PAHs) groups were targeted in the extraction of two different PM matrices: wood smoke (WS) and diesel exhaust (DE) PM. The PFE method was optimised and then compared to Soxhlet extraction for both PM matrices. The overall amounts of PAHs and their derivatives extracted from WS PM were slightly higher for the optimised PFE method (1849 ± 21 and 1863 ± 25 µg g^?1 with dichloromethane (DCM) and methanol (MeOH), respectively) than those obtained with Soxhlet extraction (1726 ± 33 and 1769 ± 22 µg g^?1 with DCM and MeOH, respectively). For DE PM (standard reference material (SRM) 2975) the overall amounts extracted by both methods were similar (average of 165 ± 6 µg g^?1), agreeing with previously published values. The detailed evaluation of extraction efficiencies for WS PM showed similar amounts for unfunctionalised PAHs (1100 µg g^?1) for both methods and solvents. For DE PM the mass yields for PAHs using PFE with DCM (62 ± 1 µg g^?1) were the highest and nearly 20% higher than those obtained with MeOH (53 ± 2 µg g^?1). The total mass yields of carboxy and hydroxy-PAHs from WS PM were also similar (412 ± 18 and 407 ± 11 µg g^?1) for PFE and Soxhlet with MeOH, and higher than when DCM was used (371 ± 5 and 379 ± 12 µg g^?1 for PFE and Soxhlet, respectively). For both matrices, the PFE yields for oxy-PAHs were higher than those obtained with Soxhlet.     

A Solid Film Electrode of Intermetallic Ag2Hg3.02 for the Direct Determination of Folic Acid in Fresh and Processed Fruit Juices

AgSIE was used for the direct analysis of folic acid (FA), with a detection limit and lower level of quantitation of 6.8×10^?10 mol L^?1 and 2.3×10^?8 mol L^?1. The analysis in fresh and processed fruits was done without any sample pretreatment. In strawberry and acerola juices, FA concentration level values were below the method detection limit. FA was detectable in peach (77.7±0.4 µg L^?1 and 64.4±0.5 µg L^?1), Persian lime (45.4±0.7 µg L^?1), pineapple Hawaii (66.2±0.4 µg L^?1), pear pineapple (35.3±0.6 µg L^?1), cashew (54.4±0.5 µg L^?1), passion fruit (73.2±0.3 µg L^?1), and apple (84.4±0.5 µg L^?1).     

Determination of traces of As,Cd, Cr,Hg, Mn,Ni, Sb,Se, Sn and Pb in human hair by triple quadrupole ICP-MS

With the wide range of metallic contaminants discharged in the environment, studying the human health requires a growing number of elements to be monitored in biological samples. Hair analysis has been suggested as a suitable tool for biomonitoring environmental and occupational exposure to toxic elements. This study describes a method for the determination of 10 trace elements in hair samples using ICP-QQQ-MS. Combining the power of the MS/MS high-energy Helium mode with the MS/MS O₂ mass-shift mode, the method offers great analytical performances with detection limits reaching 0.0014 µg g^?1 for As, 0.0016 µg g^?1 for Cd, 0.012 µg g^?1 for Cr, 0.0035 µg g^?1 for Hg, 0.0055 µg g^?1 for Mn, 0.10 µg g^?1 for Ni, 0.0012 µg g^?1 for Sb, 0.0083 µg g^?1 for Sn, 0.011 µg g^?1 for Se and Pb. The accuracy of the method was tested on a human hair ERM® certified reference material. Percent recoveries varied from 91.3% and 106.9% being always in the acceptance range of 90–110%. For all analysed elements, RSD% of repeatability ranged between 0.6% and 9.0% and those of intermediate precision did not exceed the limit of 20% being always lower than 10% (except for As). The proposed method was applied for the determination of trace elements in hair samples from 20 unexposed subjects. The geometric mean levels were as follows: Cr 0.28 µg g^?1, Mn 0.30 µg g^?1, Sn 1.04µg g^?1, Sb 0.07 µg g^?1, Hg 0.42 µg g^?1, As 0.02 µg g^?1, Cd 0.03 µg g^?1, Ni 0.51 µg g^?1, Se 0.45 µg g^?1 and Pb 1.83 µg g^?1. Element concentrations were in the same range with the reported data. The reported results may be useful for environmental exposure assessment or comparisons studies when establishing reference values of trace elements in exposed population.     

Determination of Arsenic,Mercury and Barium in Herbarium Mount Paper Using Dynamic Ultrasound-Assisted Extraction Prior to Atomic Fluorescence and Absorption Spectrometry

A dynamic ultrasound-assisted extraction method using Atomic Absorption and Atomic Fluorescence spectrometers as detectors was developed to analyze mercury, arsenic, and barium from herbarium mount paper originating from the herbarium collection of the National Museum of Wales. The variables influencing extraction were optimized by a multivariate approach. The optimal conditions were found to be 1% HNO₃ extractant solution used at a flow rate of 1 mL min^?1. The duty cycle and amplitude of the ultrasonic probe was found to be 50% in both cases with an ultrasound power of 400 W. The optimal distance between the probe and the top face of the extraction chamber was found to be 0 cm. Under these conditions the time required for complete extraction of the three analytes was 25 min. Cold vapor and hydride generation coupled to atomic fluorescence spectrometry was utilized to determine mercury and arsenic, respectively. The chemical and instrumental conditions were optimized to provide detection limits of 0.01 ng g^?1 and 1.25 ng g^?1 for mercury and arsenic, respectively. Barium was determined by graphite-furnace atomic absorption spectrometry, with a detection limit of 25 ng g^?1. By using 0.5 g of sample, the concentrations of the target analytes varied for the different types of paper and ranged between 0.4–2.55 µg g^?1 for Ba, 0.035–10.47 µg g^?1 for As, and 0.0046–2.37 µg g^?1 for Hg.     

Determination of arsenic in glycerine by flow injection,hydride generation and inductively-coupled plasma/atomic emission spectrometry

The determination of low concentrations of arsenic in glycerine is investigated with flow injection for the introduction of analyte and tetrahydroborate reagent for arsine generation, separation in a vapor-liquid flow cell, and inductively-coupled plasma/atomic emission spectrometry (i.c.p./a.e.s.). Peak areas are used to quantify arsenic in the concentration range 0.12–3.0 μg ml^?1. Peak areas for prepared standards exhibited average deviations of about 1.4% for this concentration range. The slope and intercept for a least- squares fit of area (nanocoulombs) vs. concentration (μg ml^?1) were 10.9 ± 0.17 and 0.46 ± 0.3, respectively.     

Influence of Microwave Blanching on Arsenic Speciation and Bioaccessibility in Lentinus Edodes

Humans are exposed to arsenic by inhalation and ingestion and are therefore may be affected by its toxicity. Arsenic may enter the human body by inhalation and ingestion. Cooking may alter the contents and chemical forms of arsenic. The determination of arsenic species in Lentinus edodes after microwave blanching was performed by high-performance liquid chromatography–inductively coupled plasma–mass spectrometry. Using a physiologically based extraction, the bioaccessibility of arsenic species in raw L. edodes and microwave blanching treated L. edodes were determined after the simulated gastrointestinal digestion. The arsenate (As^V), arsenite (As^III), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine, and arsenocholine did not undergo decomposition and transformation in this study. Furthermore, the total contents of arsenic in L. edodes samples were in the range of 0.1378?±?0.0044–0.2347?±?0.0144?mg/kg. Approximately 3.38–43.27% were released from samples into the blanching water after various microwave blanching treatments. The oxidation of As^III and demethylation of DMA and MMA were observed in L. edodes during digestion, increasing the likelihood of arsenic toxicity in the liver. The health risk for arsenic in L. edodes was decreased after microwave blanching because the potentially available arsenic in microwave blanching treatments L. edodes samples (83.78?±?0.9103%) were lower than those in raw L. edodes samples (88.33?±?0.7983%). L. edodes subjected to microwave blanching prior to consumption significantly decreased the total arsenic content and the risk of arsenic exposure to consumers (p?相似文献   

Emissions of biogenic volatile organic compounds from Fraxinus excelsior and Quercus robur under ambient conditions in Flanders (Belgium)

A dynamic branch enclosure system was used to measure emission rates of biogenic volatile organic compounds (BVOCs) from two common European tree species: Fraxinus excelsior and Quercus robur under ambient conditions in Flanders (Belgium). Both tree species were studied for seasonal variability of BVOC emission rates under natural biotic stress (infestations). Emissions were normalized at standard conditions of temperature and photosynthetic active radiation (PAR) (30°C and 1000?µmol?m^?2?s^?1, respectively). Emission rates from Fraxinus excelsior were highest in May (9.56?µg?g_DW ^?1?h^?1) and lowest in October (1.17?µg?g_DW ^?1?h^?1). This tree species emitted (Z)-β-ocimene, (E)-β-ocimene and α-farnesene during the entire measurement period and additionally isoprene only in May. Quercus robur showed isoprene emission variations according to the seasonal cycle with rates of 30, 106 and 29?µg?g_DW ^?1?h^?1 in May, August and October, respectively. Apart from isoprene, (E)-β-ocimene and β-caryophyllene were emitted through the entire experimental period.     

Investigation of electrochemical hydride generation coupled to microwave plasma torch optical emission spectrometry for the determination of arsenic: analytical figures of merit,interference studies and applications to environmentally relevant samples

A continuous flow thin layer electrolysis cell with a Pt cathode in combination with a microwave plasma torch operated with Ar as working gas was used for the optical emission spectrometric determination of As with the hydride technique. Under the optimised conditions the limit of detection (3σ) in the case of the As(I) 228.81 nm emission line was 81 ng mL^?1. Especially the influence of the transition metals Cu(II), Fe(III) and Ni(II), of the hydride forming elements Sb(III), Se(IV) and Sn(II) and of Na on the determination of As was studied. Cu(II) was found to be the strongest interferent, as in the presence of 100 µg mL^?1 of Cu(II) the signal for 3 µg mL^?1 of As was reduced to 4% of the signal without interferent. Sn(II) and Sb(III) were found to yield an increase of the signal for As. L-cysteine and KI/ascorbic acid (1 : 1) at a concentration of 2% were found effective to reduce the interferences of Cu(II), Fe(III) and Ni(II). For a solution containing 3 µg mL^?1 of As and 100 µg mL^?1 of Ni(II) it was shown that in the presence of L-cysteine or KI/ascorbic acid the signal for As was 99% and 94% of the one without interferent, whereas it was only 43% without masking reagents. The procedure could be used for the determination of As in a digested coal fly ash standard reference material (NIST SRM 1633a®) with a certified value of 145 ± 15 µg g^?1 for As. A concentration of 131 ± 15 µg g^?1 was found. Additionally, As could be determined in two process water samples from a copper refinery. It was found that the amount of As determined with ECHG-MPT-OES agrees well with the values determined by FAAS and ICP-OES at the 0.02 and 1.6 g L^?1 level, respectively.     

Intake of different chemical species of dietary arsenic by the japanese,and their blood and urinary arsenic levels

We calculated the intake of each chemical species of dietary arsenic by typical Japanese, and determined urinary and blood levels of each chemical species of arsenic. The mean total arsenic intake by 35 volunteers was 195±235 (15.8-1039) μg As day^?1, composed of 76% trimethylated arsenic (TMA), 17.3% inorganic arsenic (As_i), 5.8% dimethylated arsenic (DMA), and 0.8% monomethylated arsenic (MA): the intake of TMA was the largest of all the measured species. Intake of As_i characteristically and invariably occurred in each meal. Of the intake of As_i, 45-75% was methylated in vivo to form MA and DMA, and excreted in these forms into urine. The mean measured urinary total arsenic level in 56 healthy volunteers was 129±92.0 μg As dm^?3, composed of 64.6% TMA, 26.7% DMA, 6.7% As_i and 2.2% MA. The mean blood total arsenic level in the 56 volunteers was 0.73±0.57 μg dl^?1, composed of 73% TMA, 14% DMA and 9.6% As_i. The urinary TMA levels proved to be significantly correlated with the whole-blood TMA levels (r = 0.376; P<0.01).     

Polycyclic aromatic hydrocarbon and ionic compositions of atmospheric bulk deposition samples at a national park under the influence of intense barbecue smoke

The main aim of this study was to present the effects of barbecue smoke on a small-scale environment, a national park under the influence of intense barbecue smoke, and to scientifically support the sustainable usage of the park. Twelve-weekly bulk deposition samples were collected directly at the barbecuing area, and the samples were analysed for 16 US EPA’s priority PAH compounds and major ions. The mean concentrations of the individual PAHs in the bulk deposition samples ranged from 11.8 ng L^?1 (Ane) to 1085 ± 581 ng L^?1 (IcdP). The most frequently observed PAH compounds in the bulk deposition samples were Np, Anp, Flr, Phe, An, Flu, BkF, BaP and IcdP. The mean total PAH deposition fluxes were determined as 3.6 ± 5.6 µg m^?2 day^?1. The chloride, potassium and the sulphate fluxes were determined as 145.2 ± 267.8 µg m^?2 day^?1, 182.9 ± 291.9 µg m^?2 day^?1, and 111.9 ± 65.9 µg m^?2 day^?1, respectively. Dominant ions in the bulk deposition samples were potassium ion, chloride and sulphate which addressed as the fingerprint of barbecue grilling.     

Ion Chromatographic Determination of Traces of Sodium,Magnesium and Chlorine in Gadolinium Nitrate

Abstract

Two independent and sensitive ion chromatographic methods with suppressed conductivity were developed for determination of traces of Cl, Na, and Mg in gadolinium-nitrate. Na-Mg was determined by cation-exchange column after matrix separation, whereas Cl was analyzed without matrix separation by high capacity anion-exchange column. Detection limit for Cl was 0.01 µg mL^?1 in sample solution and 1 µg g^?1 in solid sample. The reproducibility (100 µL injected) was better than 3%, 3% and 4% at 50, 25 and 50 µg L^?1 level for Cl, Na, and Mg respectively. The overall precision was better than ±7% for Na-Mg and ±5% for Cl.     

Electrochemical nanostructured biosensors: carbon nanotubes versus conductive and semi-conductive nanoparticles

The aim of this work was to demonstrate that various types of nanostructures provide different gains in terms of sensitivity or detection limit albeit providing the same gain in terms of increased area. Commercial screen printed electrodes (SPEs) were functionalized with 100 µg of bismuth oxide nanoparticles (Bi₂O₃ NPs), 13.5 µg of gold nanoparticles (Au NPs), and 4.8 µg of multi-wall carbon nanotubes (MWCNTs) to sense hydrogen peroxide (H₂O₂). The amount of nanomaterials to deposit was calculated using specific surface area (SSA) in order to equalize the additional electroactive surface area. Cyclic voltammetry (CV) experiments revealed oxidation peaks of Bi₂O₃ NPs, Au NPs, and MWCNTs based electrodes at (790 ± 1) mV, (386 ± 1) mV, and (589 ± 1) mV, respectively, and sensitivities evaluated by chronoamperometry (CA) were (74 ± 12) µA mM^?1 cm^?2, (129 ± 15) ±A mM^?1 cm^?2, and (54 ± 2) ±A mM^?1 cm^?2, respectively. Electrodes functionalized with Au NPs showed better sensing performance and lower redox potential (oxidative peak position) compared with the other two types of nanostructured SPEs. Interestingly, the average size of the tested Au NPs was 4 nm, under the limit of 10 nm where the quantum effects are dominant. The limit of detection (LOD) was (11.1 ± 2.8) ±M, (8.0 ± 2.4) ±M, and (3.4 ± 0.1) ±M for Bi₂O₃ NPs, Au NPs, and for MWCNTs based electrodes, respectively.     

Calibration for Elemental Dental Tissue Analysis by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Teeth retain different elements at particular stages of life. Hence, the exposure over a selected time span may be characterized by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). A Nd:YAG laser with emission at 266?nm was coupled to a quadrupole ICP-MS for the quantitative study of historical human teeth for Sr and Ba, elements of anthropological significance. A calibration approach incorporating the experimentally derived k coefficient is reported. The coefficients were established based on the mean concentrations of the analytes determined by pneumatic nebulization ICP-MS using acid-digested calcium phosphate standards and the intensities recorded during laser ablation of corresponding standards as pellets. The k values were 0.54?±?0.05 (µg?g^?1)^?1 and 4.49?±?1.09 (µg?g^?1)^?1 for Sr and Ba, respectively. This calibration approach provided local quantitative data and demonstrated statistically significant differences in Sr concentrations in enamel and dentine.