Ultra-trace Concentrations Research Articles

Quantitation of trace polyfunctional thiols in wine by liquid chromatography quadrupole Orbitrap high-resolution mass spectrometry in parallel reaction monitoring

Polyfunctional thiols are key contributors to wine aroma due to their extremely low odor thresholds, and their quantitative analysis remains challenging as a result of their ultratrace concentrations and high reactivity. This work presents the first method based on ultra-high-performance liquid chromatography (UHPLC) coupled to quadrupole Orbitrap high-resolution mass spectrometry (HRMS) in parallel reaction monitoring (PRM) mode for quantifying thiols at nanograms per liter (ng/L) levels in wine. Thiols in wine were derivatized using 4,4′-dithiodipyridine and isolated by liquid-liquid extraction. This protocol allowed rapid sample preparation with minimum labor input and low consumable expenses. Instrumental analysis was conducted using UHPLC–quadrupole Orbitrap HRMS in PRM mode. Twenty thiol analytes, including literature-known, recently identified, and novel thiols were selected and validated by the optimized method in three wine matrices. The overall analytical performances demonstrated by this method were equivalent, and in most cases, greater than many previously developed GC–MS or LC–MS methods. The validated method was applied to analyze a selection of wines in which 12 thiols were quantified.

Depth dimension in seepage detection: Insights for exploration and geological gas storage surveillance

The search for surface hydrocarbon seeps has historically served as a fundamental tool in the early stages of oil and gas exploration. However, as easily detectable surface hydrocarbon seeps become increasingly scarce, advancement in analytical capabilities have shifted the focus towards detecting ultra-trace levels of hydrocarbons, commonly referred to as microseepages. While it is critical to understand the distribution of hydrocarbon microseepage for assessing petroleum systems and optimizing exploration efforts, the role of sampling depth in the detection of microseepage remains poorly understood. In this study, we investigated the influence of sampling depth on microseepage detection, using passive soil-gas sampling techniques at depths ranging from 0.5 to 10 m at sites with hydrocarbon-bearing reservoirs and dry wells. Organic geochemical analysis, including thermal desorption-gas chromatography-mass spectrometry (GC-MS), was employed to identify and quantify hydrocarbon and nonhydrocarbon compounds.The study result demonstrates that sampling at the Minimal Interference Zone (MIZ) depths of 5 m or greater significantly mitigates the risk of interference signals, thereby enabling the identification and quantification of hydrocarbon microseepages at trace and ultra-trace concentrations. At these depths, the attenuation of non-hydrocarbon compounds was observed, making the hydrocarbon signal markedly more distinguishable. Geochemical characterization of the samples revealed spatial and vertical heterogeneity in the distribution of hydrocarbon compounds, indicative of variations in the microseepage mechanisms potentially influenced by factors such as sedimentary basin settings and secondary alterations associated with the vadose zone. By utilizing passive soil-gas sampling techniques coupled with GC-MS, this study emphasizes the importance of sampling depth to improve the detection of reliable microseepage signal while reducing interference and background noise. The proposed technique not only refines existing methodologies for petroleum system assessments but also paves the way for broader geological applications. Specifically, the approach offers critical insights for the development of high-resolution geochemical surveys adaptable for surface background profiling in CO2 sequestration projects to monitor for storage efficiency and seal integrity.

Bio-Based Materials for Electrochemical Detection of Bisphenol A

Bisphenol A is a widely used endocrine disruptor known for its toxicity and prevalence in the environment. It contaminates drinking water, especially when plastic bottles are exposed to Sunlight. Rapid, on-site detection of BPA in drinking water is crucial for protecting human health and the environment. Herein, we developed an electrochemical sensor for detecting and monitoring bisphenol A in water bodies utilizing biobased materials. The device uses a biopolymeric membrane with agarose and gelified green tea tannins (GT/Agar). A sensitive part was made using this natural composite due to its high ability to attach bisphenol A to tannin monomers. Green tea tannins were purified and characterized through HPLC, FTIR, SEM, and AFM. The electrochemical activity of the GT-Agar/Au sensor is also evaluated by electrochemical impedance spectroscopy, cyclic voltammetry, square wave voltammetry and scan rate. Based on its redox signal under the optimal experimental conditions, this sensor has a detection range of 10−16 M to 10−4 M, a limit of detection of 1.52 to 10−17 M and very high selectivity. The proposed sensor successfully determined BPA levels from ultra-trace concentrations in bottled water samples, achieving satisfactory recovery rates. Compared to the results obtained using HPLC, it demonstrates high reliability.

Cyanotoxin Monitoring and Detection Using Passive Sampling Application

Cyanobacterial blooms in water have been extensively studied as they produce bioactive and toxic metabolites, commonly known as cyanotoxins. Additionally, the presence of cyanobacteria and, consequently, the production of cyanotoxins, have increased in extent and frequency worldwide. Therefore, the risk associated with the presence of these microorganisms and their toxins has become a matter of great concern. On the other hand, conventional processes for water treatment are inefficient for their elimination and/or degradation, so their presence in water persists at trace and ultra-trace concentrations. In this regard, it is important to develop alternatives to monitor cyanotoxins and allow their detection at low levels in water supply and purification systems, in order to ensure water of good quality for human consumption. In this work, different methodologies, implemented both at laboratory scale and in situ in aqueous bodies, are described. Among these methodologies, traditional and passive techniques are highlighted. Appropriate analytical and sample preparation methods used in the detection and quantification of cyanotoxins are also addressed. It was found that the use of passive samplers is a convenient and a cost-effective method of identifying the presence of these toxins in water at concentrations in the order of µg/L and ng/L. Moreover, studying the by-products generated from the degradation of natural toxins in aquatic environments and evaluating their possible adverse effects is crucial in terms of the management and control of cyanobacteria and cyanotoxin pollution in water.

High enrichment factors in chemical analysis of progestins and in bioassays: insights beyond trace levels.

Concerns are growing about adverse effects of progestins on biota, even at ultra-trace concentrations. The enrichment factor (EF) from extraction of analytes in environmental samples that is needed for sample pre-concentration can affect not only performance of the analytical method but also the matrix effect. Therefore, the present study aimed to assess the influence of high sample EF on performance of the high-performance liquid chromatography with atmospheric pressure chemical ionization and photoionization coupled with high-resolution mass spectrometry (HPLC-APCI/APPI-HRMS) method for analysis of progestins in waste water treatment plant (WWTP) effluents and surface waters and analysis of (anti-)progestogenic activities measured by (anti-)PR-CALUX bioassays. The results showed that HPLC-APCI/APPI-HRMS coupled with solid-phase extraction and a high EF (33,333 Lwater/Lextract) enabled the detection of more compounds compared to samples with lower sample EF (10,000 Lwater/Lextract). The matrix effect did not increase proportionally compared to lower EFs (10,000 and 16,666 Lwater/Lextract), and lower limits of quantification were achieved in WWTP effluents and surface waters. The results of bioassays have shown that relative EF of 25 Lwater/Lbioassay appears high enough to detect progestogenic activity in treated waste water. Our study is one of the first to provide insights into sample pre-concentration in analysis of progestins and progestogenicity in aquatic environments.

Analysis of carbamate and organophosphorus pesticide in agricultural irrigation water by Liquid Chromatography - Mass Spectrometry

So far, the ultra-trace concentration of pesticide residues in environmental samples has challenged many analytical techniques, which are used to detect simultaneously organophosphorus and carbamate with various polarities. In this study, the OASIS-HLB column was modified by the reagent 1,8-Dihydroxy-2-(4-sulfophenylazo)naphthalene-3,6-disulfonic to enhance the retention of polar pesticides. Both real irrigation water and distilled water samples were applied to validate the determination method of ten carbamates and thirty-eight organophosphorus pesticides all together using LC-MS. According to the results, the linear interval of the method ranged from 1.0 to 100 µg/L, the detection limit was as low as 5.0 µg/L, the relative standard deviations presented less than 8.0%, and the recoveries were ranging between 60% and 112%. Moreover, in the irrigation water samples which were collected in both dry and rainy seasons in ten stations around the agricultural area, five compounds were found, including fenamiphos, terbufos, aldicarb, propoxur, and methiocarb. In the midst of those sampling areas, the Environmental Impact Quotient Field Use Rating of detected pesticide residues presented a high value - 272 at one station, which indicates a high risk for the surrounding environment as well as the local people’s health.

A nanotrap infused ultrathin hybrid composite material for rapid and highly selective entrapment of 99TcO4.

99Tc is one of the potentially toxic radioactive substances owing to its long half-life and a high degree of environmental mobility. Hence, the sequestration of 99Tc from radioactive waste has become enormously important and a contemporary research priority. However, selective extraction of this species in its stable oxoanionic form (99TcO4 -) is very challenging on account of bottlenecks such as low charge density, less hydrophilic nature, etc. Herein, an ultrathin hybrid composite material has been strategically designed and fabricated by covalent anchoring of a chemically stable amino functionalized nanosized cationic metal-organic polyhedron with a positively charged robust ionic covalent organic framework. The resulting thin-layer-based hybrid composite presented multiple exfoliated exposed interactive sites, including a Zr(iv)-secondary building unit, amine and triaminoguanidine functional groups, which can selectively interact with TcO4 - oxoanions through a synergistic combination of electrostatic, H-bonding and various other supramolecular interactions. Thus synthesized function-tailored composite, by virtue of its multiple unique characteristics, manifested an ultrafast and very selective, high distribution coefficient (∼106 mL g-1), as well as recyclable entrapment of TcO4 - oxoanions from the complex mixture of superfluous (∼5000-fold) other interfering anions in both high and ultra-trace concentrations along with simulated nuclear waste and from different water systems. Dynamic flow-through experiments were conducted with the membrane of the hybrid material in simulated wastewater, which reduced the concentration of ReO4 - (surrogate of radioactive TcO4 -) to below the WHO permissible level with rapid sequestration kinetics and excellent selectivity over excessive competing anions.

Interaction of reactive mercury with surfaces and implications for atmospheric mercury speciation measurements

Accurate measurement of atmospheric reactive mercury (RM) presents analytical challenges due to its reactivity and ultra-trace concentrations. In the last decade, use of the University of Nevada, Reno – Reactive Mercury Active System (RMAS) for RM measurements has increased, since it has been shown to be more accurate than the industry standard, the Tekran 2537/1130/1135 system. However, RMAS measurements also have limitations, including long time resolution and sampling biases associated with membranes used for RM sampling. We therefore investigated the use of higher sampling flow rates to reduce sampling time and tested alternative membrane materials using both ambient air sampling and controlled laboratory experiments with a gaseous oxidized mercury (GOM) calibrator. Results indicated that increasing the RMAS sampling flow had a negative impact on determined RM concentrations. RM concentrations at 2 L min−1 were 10% and 30–50% lower than at 1 L min−1 in spring/summer and winter, respectively. However, the chemical composition of RM captured on membranes was not impacted by the increased flow rate. Membranes currently used in the RMAS performed better than numerous alternatives with similar composition, retaining Hg more efficiently. Both ambient air sampling and laboratory experiments revealed that membranes designed to retain only particulate-bound mercury (PBM) also retained significant amounts of GOM. PBM membranes based on borosilicate glass designs retained more than 70% of GOM.

Efficient dual sensor based on modified NH2-UiO-66(Zr) MOF for sensitive and rapid monitoring of ultra-trace arsenic (III) in aqueous media

This research aimed to develop a new zirconium-based sensitive material called the 5Cl2HA=(Zr) MOF sensor. The sensor was created by condensing 5-Chloro-2-hydroxyacetophenone with NH2-UiO-66(Zr). Its effectiveness, selectivity, and sensitivity were demonstrated by successfully detecting ultra-trace concentrations of As3+ ions in real water samples using spectrophotometric and fluorometric methods. The characterization of the 5Cl2HA=(Zr) MOF sensor involved various techniques, including SEM, XRD, XPS, BET, and FT-IR, which confirmed its successful synthesis and provided insights into its structural and surface properties. Optimization experiments were conducted to determine the best conditions for detecting As3+ ions using colorimetric and fluorometric methods. The sensor exhibited a rapid detection capability, achieving a stable spectroscopic signal in less than 10 s. The proposed methods adhered to (ICH) guidelines, and parameters such as precision, the limit of detection (LOD), the limit of quantification (LOQ), and linearity were evaluated. The spectrophotometric technique demonstrated the lowest LOD for As3+ ions, with a value of 0.0607 ppm. The recyclability of the sensor was investigated, showing successful reuse up to five times with 85% efficiency by employing 0.01 M HCl as the eluent for regeneration. Furthermore, the performance of the 5Cl2HA=(Zr) MOF sensor was evaluated using various real samples, including groundwater and city water samples, demonstrating high sensitivity and selectivity in detecting As3+ ions in these complex matrices. These findings highlight the sensor's potential for real-world applications.

Chromoionophoric probe imbued porous polymer monolith as a Three-in-One Solid-state Naked-eye sensor for the selective sensing and recovery of Ultra-trace Lead, Mercury, and cadmium ions from Industrial/Environmental samples

This article presents a simple, low-cost, eco-benign, and portable naked-eye solid-state sensor for the selective and sensitive colorimetric detection and recovery of ultra-trace concentrations of Pb(II), Hg(II) and Cd(II) from environmental/industrial sources. For solid-state sensing, an indigenously synthesized polymer monolith, i.e., poly(VAn-EGDMA), in-built with high surface area and interlinked meso-/macro-pore network serves as a template for the voluminous and uniform decoration of chromoionophoric probe molecules, i.e., 2-((1H-benzo[d]imidazol-2-yl)diazenyl)-4-methoxyphenol (IDMP) onto the monolith perforations via. direct immobilization technique. The structural and surface topological properties of poly(VAn-EGDMA) monolith and probe-loaded polymer, i.e., IDMP@poly(VAn-EGDMA) sensor, are characterized through FE-SEM, HR-TEM, EDAX, XPS, p-XRD, SAED, FT-IR, BET and BJH analysis. The IDMP@poly(VAn-EGDMA) sensor forms a selective/stable metal complex through visually imposing enhanced charge transfer color transitions from its original canary yellow to dark denim blue, brownish green and lapis blue for varying concentrations of Pb(II), Hg(II) and Cd(II), respectively. The sensor reusability has been tested by decomplexing the IDMP-Mn+ complex with 0.1 M HCl and repeating the sensor performance consistently for eight consecutive cycles. The IDMP@poly(VAn-EGDMA) sensor exhibits pH-dependent ion-sensing, demonstrating a wide linear response range for Pb(II) (0–200 ppb), Hg(II) (0–150 ppb), and Cd(II) (0–150 ppb), with a detection limit of 0.44, 0.56, and 0.52 ppb, respectively. The three-in-one sensor exhibits pH-dependent sequential selectivity, chemical/thermal stability, and data reliability/reproducibility, thus proving effective for on-spot sensing of various sources of contaminated samples.

Ultratrace PFAS Detection Using Amplifying Fluorescent Polymers.

Per- and poly(fluoroalkyl) substances (PFAS) are environmentally persistent pollutants that are of growing concern due to their detrimental effects at ultratrace concentrations (ng·L-1) in human and environmental health. Suitable technologies for on-site ultratrace detection of PFAS do not exist and current methods require complex and specialized equipment, making the monitoring of PFAS in distributed water infrastructures extremely challenging. Herein, we describe amplifying fluorescent polymers (AFPs) that can selectively detect perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) at concentrations of ng·L-1. The AFPs are highly fluorinated and have poly(p-phenylene ethynylene) and polyfluorene backbones bearing pyridine-based selectors that react with acidic PFAS via a proton-transfer reaction. The fluorinated regions within the polymers partition PFAS into polymers, whereas the protonated pyridine units create lower-energy traps for the excitons, and emission from these pyridinium sites results in red-shifting of the fluorescence spectra. The AFPs are evaluated in thin-film and nanoparticle forms and can selectively detect PFAS concentrations of ∼1 ppb and ∼100 ppt, respectively. Both polymer films and nanoparticles are not affected by the type of water, and similar responses to PFAS were found in milliQ water, DI water, and well water. These results demonstrate a promising sensing approach for on-site detection of aqueous PFAS in the ng·L-1 range.

Single particle inductively coupled plasma mass spectrometry: A new method to detect geochemical anomalies in stream sediments

Single particle inductively coupled plasma mass spectrometry (spICP-MS) offers a new tool to explore for concealed mineral deposits. Through detection of metal nanoparticles (NPs) present in stream sediments, subtle geochemical anomalies may be identified farther from their source. Geochemical exploration with spICP-MS lowers the detection limit substantially from conventional ICP-MS for insoluble elements of interest. Analyzing only 197Au signal generated by individual NPs rather than an integrated signal, which can have a significant contribution from detector noise, resulted in a 53-fold reduction in detection limit compared to a digestion/quadrupole ICP-MS determination (21 ng∗L−1 to 0.39 ng∗L−1). Method development included analysis of dilute suspensions of manufactured 50 nm Au particles and three stream sediment samples (5–15 g sonicated in 20 mL 25 μM 11-mercaptoundeconoic acid). Au and Ag NPs were identified in the two sites downstream from a known area of mineralization, whereas none were detected in a background stream sediment site. Average particle numbers and masses of Au and Ag were highest in the sample closest to known mineralization. Additional results indicated that use of surfactant is an important contribution to the procedure. This pilot study of three sites provides a proof of concept in the analysis of spICP-MS for determination of Au and Ag in stream sediment samples, which could augment or improve current cyanide/acid dissolution/ICPMS methods for the ultra-trace concentration range.

A Further Insight into Extraction Procedures Suitable for Separation of Gold Nanoparticles from Environmental Waters

Gold nanoparticles (AuNP) are being utilized in an ever-expanding number of applications ranging from scientific research to industrial processes. Increasing nanoparticle emissions in the environment have become of public and academic concern. Since the effects of AuNP on human health are not fully understood, the accumulation of reliable and detailed data is critical for the assessment of their potential risk of harm to humanity. Even their concentrations in natural and engineered water systems do not belong to commonly published data. To obtain such information, the environmental chemists use various sophisticated analytical methods that are often very expensive. Therefore, this paper aims to challenge the analytical potential and advantages of cheaper and equally reliable alternatives that couple the well-established extraction procedures with common spectrometric methods to quantify the ultratrace concentrations of AuNP in complex aqueous matrices. Both types of extraction procedures, solvent extractions as well as sorbent extractions, are discussed in the text. A detailed inspection of different types of interactions that are responsible for the ability to selectively separate AuNP from mixtures containing various ionic species, gold ions, other metallic nanoparticles, and dissolved organic matter can be found in this overview. The examples of the tolerance limits reported for several coexisting components of interest are also given. Practical applications of the extraction procedures, summarized in this article, were demonstrated in analysis of actual environmental matrices, such as tap, river, lake, brook, mineral, and sea waters.

Removal of 241Am from Aqueous Solutions by Adsorption on Sponge Gourd Biochar

Luffa cylindrica biomass was converted to biochar and the removal of 241Am by pristine and oxidized biochar fibers was investigated in laboratory and environmental water samples. This species has the added advantage of a unique microsponge structure that is beneficial for the production of porous adsorbents. The main purpose of this study was to valorize this biomass to produce an efficient adsorbent and investigate its performance in radionuclide-contaminated waters. Following the preparation of Am3+ solutions at a concentration of 10-12 mol/L, the adsorption efficiency (Kd) was determined as a function of pH, adsorbent mass, ionic strength, temperature, and type of aqueous solution by batch experiments. At the optimum adsorbent dose of 0.1 g and pH value of 4, a log10Kd value of 4.2 was achieved by the oxidized biochar sample. The effect of temperature and ionic strength indicated that adsorption is an endothermic and entropy-driven process (ΔH° = -512 kJ mol-1 and ΔS° = -1.2 J K-1 mol-1) leading to the formation of inner-sphere complexes. The adsorption kinetics were relatively slow (24 h equilibrium time) due to the slow diffusion of the radionuclide to the biochar surface and fitted well to the pseudo-first-order kinetic model. Oxidized biochar performed better compared to the unmodified sample and overall appears to be an efficient adsorbent for the treatment of 241Am-contaminated waters, even at ultra-trace concentrations.

Determination of Plutonium and Other Actinides by Accelerator Mass Spectrometry

Accelerator mass spectrometry (AMS) is a very sensitive method for the determination of ultra-trace concentrations of long-lived radionuclides of actinides, such as uranium, plutonium, neptunium, or americium, mostly in environmental samples. This article focuses mainly on the determination of plutonium isotopes occurring in nature due to human nuclear activity, mainly 239Pu and 240Pu. The determination of the 239/240Pu ratio enables one to identify the origin of plutonium emission in the environment, namely, whether it originates from global fallout or releases from nuclear facilities.
 Actinides determination plays also an important role in environmental studies, where the measurement of individual radionuclides, such as 236U, 237Np, 239Pu, 240Pu and 241Am, can monitor the environmental processes, especially migration, sedimentation or deep ocean currents. The overall sample preparation procedure for AMS includes evaporation and pre-concentration of the sample to reduce its volume or sample decomposition. After that, to eliminate isobaric interferences, it is necessary to separate the actinides from other elements and, in most cases, also from each other. This paper describes procedures of the separation of actinides from various environmental samples, as well as the preparation of the oxide and fluoride target materials which is crucial for the measurement in terms of the isobaric interferences suppression, material quantity and the detection sensitivity.

Effects of exfoliated graphite addition in ultra-trace concentration on industrial-scale lead-acid battery performance

The present investigation has the main objective to elucidate the hypothesis whether the addition of graphite nanoplatelets in ultra-trace concentrations (mg.kg-1) in negative plates are able to affect the electrochemical behavior of lead-acid batteries. The 60 Ah full scale batteries were produced in an industrial unit and assembled with three types of graphite nanoplatelets of different exfoliation intensities and in five different concentrations. Through electrical tests, it was possible to establish that certain concentrations of types of these additives are capable of increasing CCA performance, charge acceptance and PSOC cycling. The analysis of the structure (new, charged and discharged and post mortem) through SEM and evaluation of the macroporosity variation identified that the increase in electrochemical performance is associated with the structural change caused by the addition of these additives. Due to the small amounts of additives involved, the polarization is only slightly altered, signaling that the water loss is not appreciably affected. Discharge tests with constant current and interruptions reinforce the idea that the structure can be positively modified to increase electrochemical performance.

Solid-state naked-eye sensing of Cu(II) from industrial effluents and environmental water samples using probe integrated polymeric sensor materials

We report on the fabrication of two eco-friendly and fast-responsive solid-state optical sensors for the reliable sensing of Cu(II) ions from natural and industrial wastewater. The solid-state template constitutes indigenously prepared bimodal macro-/meso-porous channels of a monolithic polymer framework of uniform surface morphology, high surface area, and capacious porosity. For the naked-eye colorimetric detection, two chromoionophoric probes i.e., 4-butyl-N-((1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)carbamothioyl)benzamide (BDICB) and 4-butyl-N-(2-(thiophene-2-carbonyl)hydrazine-1-carbonothioyl)benzamide (BTHCB) that offer exclusive ion-selectivity and sensitivity for Cu(II) are synthesized. The monolithic template exhibits multi-diffusible display sites for the uniform anchoring of the probe molecules that act as naked-eye colorimetric ion sensors. The structural and surface profile of the monolithic sensor materials are studied using HR-TEM, FE-SEM, EDAX, SAED, p-XRD, XPS, FT-IR, and BET/BJH analysis. The probe-anchored monolithic materials reciprocate a brilliant visual color shift from an initial colorless state to apple green and greyish black, respectively, for BDICB and BTHCB anchored sensor materials, with varying concentrations of Cu(II), with a response time of ≤1 min. Besides, the sensor fabrication pursues a simple direct encapsulation of probe molecules onto the polymer monolith. The proposed solid-state sensors are certified using simulated and real samples that reflect a reliable detection limit of 0.11 & 0.14 ppb and a quantification limit of 0.38 & 0.45 ppb for Cu(II) ions, respectively, using BDICB & BTHCB anchored polymer monolith sensors. The proposed solid-state colorimetric ion-sensors exhibit dual functionality in serving as a viable ion-sensing tool and concentrator for recovering ultra-trace concentrations of Cu(II) ions.

A highly sensitive method for uranium quantification in water samples at ultra-trace level by total reflection X-ray fluorescence, after its direct pre-concentration on the surface of amidoxime functionalized quartz sample supports

In this work we have developed a Total reflection X-Ray Fluorescence (TXRF) based methodology for the determination of uranium in natural water samples at ultra-trace concentration level. The methodology involves functionalization of quartz sample supports used for TXRF measurements with (3-Amidoxy) triethoxysilane, which has very high uranium uptake efficiency. (3-Amidoxy) triethoxysilane has been synthesized from (3-Cyanopropyl) triethoxysilane (CPTS). This amidoxime functionalized sample supports, simply needed to be dipped in the uranium solution for 3 h after which, it can be directly taken for TXRF measurements. The developed methodology is very fast, simple with less sample preparation steps involved. The present work utilizes Rayleigh scattered peak to construct the calibration curve for the quantification purpose. The developed methodology has improved accuracy as well as precision for the quantification of uranium at such low concentrations level. The detection limit and accuracy obtained are 0.013 ng/mL (13 ppt) and 1.9%, respectively which are the lowest using any X-Ray Fluorescence based method, to the best of our knowledge. The method was successfully applied for the U determination in natural water samples like ground water, river water and sea water.

Analysis of microsamples of biological fluids via inductively coupled plasma-tandem mass spectrometry using a micro-flow injection system coupled to a high-efficiency sample introduction setup

In many fields, the sample volume available is the limiting factor for ultra-trace elemental analysis, and thus, the development of novel methods that can extract more information from lower sample amounts is a topic that deserves attention. In this work, the performance of a micro-flow injection system coupled to either (1) a traditional or (2) a high-efficiency sample introduction system has been evaluated for the analysis of liquid microsamples using inductively coupled plasma-mass spectrometry (ICP-MS). The figures of merit with each sample introduction system have been studied in a wide range of sample volumes and sample uptake rates. The use of a high-efficiency low-volume sample introduction system provided a > 4-fold enhanced sensitivity as compared to the traditional one, while the former setup was demonstrated being capable of accurately delivering volumes as low as 5 or 10 μL to the ICP. Even for such low sample amounts, good linearity (>0.9998) and repeatability (RSD down to 0.2%) were experimentally demonstrated, while matrix effects were lower with the high-efficiency sample introduction system. The use of an internal standard adequately corrected for changes in sample introduction conditions, allowing quantitative results to be obtained by using a single set of calibration data obtained at fixed operating conditions (sample volume and sample uptake rate), with a bias <15% (typical acceptance criterion for clinical QC analysis). The set-up characterized was successfully applied to the analysis of microsamples of biological fluids (down to 0.4 μL of sample volume). Tandem ICP-MS (ICP-MS/MS) was used to overcome spectral overlap (chemical resolution with a mixture of NH3/He) affecting the determination of six clinically relevant metals (Co, Cr, Mn, Ni, Ti and V) at ultra-trace concentration levels. No significant differences were found between the results obtained in this work and the reference values, even when using different sample introduction conditions for the measurement of calibration standards and samples.

Preconcentration and Separation of Gold Nanoparticles from Environmental Waters Using Extraction Techniques Followed by Spectrometric Quantification.

The quantification of gold nanoparticles (AuNP) in environmental samples at ultratrace concentrations can be accurately performed by sophisticated and pricey analytical methods. This paper aims to challenge the analytical potential and advantages of cheaper and equally reliable alternatives that couple the well-established extraction procedures with common spectrometric methods. We discuss several combinations of techniques that are suitable for separation/preconcentration and quantification of AuNP in complex and challenging aqueous matrices, such as tap, river, lake, brook, mineral, and sea waters, as well as wastewaters. Cloud point extraction (CPE) has been successfully combined with electrothermal atomic absorption spectrometry (ETAAS), inductively coupled plasma mass spectrometry (ICP-MS), chemiluminescence (CL), and total reflection X-ray fluorescence spectrometry (TXRF). The major advantage of this approach is the ability to quantify AuNP of different sizes and coatings in a sample with a volume in the order of milliliters. Small volumes of sample (5 mL), dispersive solvent (50 µL), and extraction agent (70 µL) were reported also for surfactant-assisted dispersive liquid–liquid microextraction (SA-DLLME) coupled with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). The limits of detection (LOD) achieved using different combinations of methods as well as enrichment factors (EF) varied greatly, being 0.004–200 ng L−1 and 8–250, respectively.