1
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Mahmoud A, Gajdár J, Brites Helú M, Etienne M, Herzog G. Local electrochemical sample acidification for the detection of Pb 2+ traces. Analyst 2024. [PMID: 39229833 DOI: 10.1039/d4an00647j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
Electrochemical detection of pollutants (e.g. heavy metals) in real samples often requires the adjustment of pH to allow optimal sensitivity. Such sample pretreatment can be challenging for on-site applications as it implies the use of valves, pumps and storage of base or acid solutions. We report here the use of an electrochemical approach for the control of water sample pH. It offers the possibility for local pH adjustment while simultaneously detecting Pb2+, whose detection sensitivity is pH dependent. An effective electrochemical method through local electrochemical acidification is performed to detect Pb2+ within a desired pH range without the need to add chemical reagents. Local acidification is based on water electrolysis. An anodic potential is applied to an acidifier to rapidly electrogenerate protons. This allows the sample pH to be tailored to the optimal detection condition. Reduction of the Pt oxide layer formed on the acidifier is key to obtain repeatable results in Pb2+ detection. On-site sample acidification is combined with anodic stripping voltammetry to reach a detection limit of 6 ppb (30 nM), which is lower than the World Health Organization guideline value for Pb2+ level in drinking water.
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Affiliation(s)
- Amira Mahmoud
- Université de Lorraine, CNRS, LCPME, F-54000 Nancy, France.
| | - Július Gajdár
- Université de Lorraine, CNRS, LCPME, F-54000 Nancy, France.
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2
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Yang R, Su Y, Ren T, Li Y, Deng Y, Zheng C. Automatic and Matrix Interference-Free Acid-Base Titration by Coupling CO 2 Vapor Generation with Microplasma Carbon Optical Emission Spectrometry. Anal Chem 2023; 95:17238-17245. [PMID: 37966796 DOI: 10.1021/acs.analchem.3c02893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
Acid-base titration of complex samples is conducive to the rapid evaluation of the degree and risk of environmental pollution to some extent. However, the traditional titration methods usually suffer from serious interference. Herein, an automatic acid-base titration method coupling miniature point discharge optical emission spectrometry (μPD-OES) with CO2 vapor generation was described for the precise, sensitive, and matrix interference-free acid-base titration of complex samples, particularly those with high color intensity, salinity, and turbidity such as wastewater and soil samples. In this work, acid-base titration was carried out in a chemical vapor generator where CO2 was generated through the addition of HCl or NaHCO3, thus enabling efficient separation of CO2 from a complex matrix. The generated CO2 was subsequently swept into the miniaturized point discharge for excitation and further detection by μPD-OES, where the carbon atomic emission at 193.0 nm was monitored. According to the consumed volume and concentration of HCl, accurate and automatic measurements of OH-, CO32-, and HCO3- can be accomplished. The proposed method possesses a high sensitivity of μPD-OES for the detection of CO2 with a relative standard deviation of below 3.0%. Moreover, the proposed system not only retains several unique advantages of accuracy, simplicity, and elimination of the use of complicated, expensive, and high power-consumption instruments but also alleviates the color and turbid interference from complex samples such as dyeing wastewater samples, oilfield water samples, and soil samples. It retains a promising potential application for titration analysis of other samples such as sludge, sediment, and landfill leachate.
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Affiliation(s)
- Rui Yang
- College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu, Sichuan 610059, China
- Key Laboratory of Green Chemistry & Technology of MOE, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Yubin Su
- Key Laboratory of Green Chemistry & Technology of MOE, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Tian Ren
- Key Laboratory of Green Chemistry & Technology of MOE, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Yuanyuan Li
- Key Laboratory of Green Chemistry & Technology of MOE, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Yurong Deng
- Key Laboratory of Green Chemistry & Technology of MOE, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| | - Chengbin Zheng
- Key Laboratory of Green Chemistry & Technology of MOE, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
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3
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Wiorek A, Cuartero M, Crespo GA. Selective Deionization of Thin-Layer Samples Using Tandem Carbon Nanotubes-Polymeric Membranes. Anal Chem 2023; 95:15681-15689. [PMID: 37815334 PMCID: PMC10603610 DOI: 10.1021/acs.analchem.3c02965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 09/06/2023] [Indexed: 10/11/2023]
Abstract
Herein, we investigate the selective deionization (i.e., the removal of ions) in thin-layer samples (<100 μm in thickness) using carbon nanotubes (CNTs) covered with an ionophore-based ion-selective membrane (ISM), resulting in a CNT-ISM tandem actuator. The concept of selective deionization is based on a recent discovery by our group ( Anal. Chem. 2022, 94, 21, 7455-7459), where the activation of the CNT-ISM architecture is conceived on a mild potential step that charges the CNTs to ultimately generate the depletion of ions in a thin-layer sample. The role of the ISM is to selectively facilitate the transport of only one ion species to the CNT lattice. To estimate the deionization efficiency of such a process, a potentiometric sensor is placed less than 100 μm away from the CNT-ISM tandem, inside a microfluidic cell. This configuration helped to reveal that the selective uptake of ions increases with the capacitance of the CNTs and that the ISM requires a certain ion-exchanger capacity, but this does not further affect its efficiency. The versatility of the concept is demonstrated by comparing the selective uptake of five different ions (H+, Li+, Na+, K+, and Ca2+), suggesting the possibility to remove any cation from a sample by simply changing the ionophore in the ISM. Furthermore, ISMs based on two ionophores proved to achieve the simultaneous and selective deionization of two ion species using the same actuator. Importantly, the relative uptake between the two ions was found to be governed by the ion-ionophore binding constants, with the most strongly bound ion being favored over other ions. The CNT-ISM actuator concept is expected to contribute to the analytical sensing field in the sense that ionic interferents influencing the analytical signal can selectively be removed from samples to lower traditional limits of detection.
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Affiliation(s)
- Alexander Wiorek
- Department
of Chemistry, School of Engineering Science in Chemistry, Biochemistry
and Health, KTH Royal Institute of Technology, Teknikringen 30, SE-114 28 Stockholm, Sweden
| | - Maria Cuartero
- Department
of Chemistry, School of Engineering Science in Chemistry, Biochemistry
and Health, KTH Royal Institute of Technology, Teknikringen 30, SE-114 28 Stockholm, Sweden
- UCAM-SENS, Universidad
Católica San Antonio de Murcia,
UCAM HiTech, Avda. Andres
Hernandez Ros 1, 30107 Murcia, Spain
| | - Gastón A. Crespo
- Department
of Chemistry, School of Engineering Science in Chemistry, Biochemistry
and Health, KTH Royal Institute of Technology, Teknikringen 30, SE-114 28 Stockholm, Sweden
- UCAM-SENS, Universidad
Católica San Antonio de Murcia,
UCAM HiTech, Avda. Andres
Hernandez Ros 1, 30107 Murcia, Spain
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4
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Wiorek A, Steininger F, Crespo GA, Cuartero M, Koren K. Imaging of CO 2 and Dissolved Inorganic Carbon via Electrochemical Acidification-Optode Tandem. ACS Sens 2023; 8:2843-2851. [PMID: 37392165 PMCID: PMC10391712 DOI: 10.1021/acssensors.3c00790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Accepted: 06/06/2023] [Indexed: 07/03/2023]
Abstract
Dissolved inorganic carbon (DIC) is a key component of the global carbon cycle and plays a critical role in ocean acidification and proliferation of phototrophs. Its quantification at a high spatial resolution is essential for understanding various biogeochemical processes. We present an analytical method for 2D chemical imaging of DIC by combining a conventional CO2 optode with localized electrochemical acidification from a polyaniline (PANI)-coated stainless-steel mesh electrode. Initially, the optode response is governed by local concentrations of free CO2 in the sample, corresponding to the established carbonate equilibrium at the (unmodified) sample pH. Upon applying a mild potential-based polarization to the PANI mesh, protons are released into the sample, shifting the carbonate equilibrium toward CO2 conversion (>99%), which corresponds to the sample DIC. It is herein demonstrated that the CO2 optode-PANI tandem enables the mapping of free CO2 (before PANI activation) and DIC (after PANI activation) in complex samples, providing high 2D spatial resolution (approx. 400 μm). The significance of this method was proven by inspecting the carbonate chemistry of complex environmental systems, including the freshwater plant Vallisneria spiralis and lime-amended waterlogged soil. This work is expected to pave the way for new analytical strategies that combine chemical imaging with electrochemical actuators, aiming to enhance classical sensing approaches via in situ (and reagentless) sample treatment. Such tools may provide a better understanding of environmentally relevant pH-dependent analytes related to the carbon, nitrogen, and sulfur cycles.
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Affiliation(s)
- Alexander Wiorek
- Department
of Chemistry, School of Engineering Science in Chemistry, Biochemistry
and Health, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
| | - Fabian Steininger
- Aarhus
University Centre for Water Technology, Department of Biology, Section
for Microbiology, Aarhus University, Aarhus 8000, Denmark
| | - Gaston A. Crespo
- Department
of Chemistry, School of Engineering Science in Chemistry, Biochemistry
and Health, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
- UCAM-SENS,
Universidad Católica San Antonio de Murcia, UCAM HiTech, Avda. Andres
Hernandez Ros 1, Murcia 30107, Spain
| | - Maria Cuartero
- Department
of Chemistry, School of Engineering Science in Chemistry, Biochemistry
and Health, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
- UCAM-SENS,
Universidad Católica San Antonio de Murcia, UCAM HiTech, Avda. Andres
Hernandez Ros 1, Murcia 30107, Spain
| | - Klaus Koren
- Aarhus
University Centre for Water Technology, Department of Biology, Section
for Microbiology, Aarhus University, Aarhus 8000, Denmark
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5
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Tarannum N, Kumar D, Agrawal R. Facile Titrimetric Assay of Lysophosphatidic Acid in Human Serum and Plasma for Ovarian Cancer Detection. J Cancer Prev 2023; 28:31-39. [PMID: 37434795 PMCID: PMC10331031 DOI: 10.15430/jcp.2023.28.2.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 07/13/2023] Open
Abstract
Herein, an instrument free facile acid-base titrimetric methodology is reported for lysophosphatidic acid (LPA) measurement in serum and plasma samples for ovarian cancer detection. The concept is based on the titrimetric method in which alkaline solution was titrated with free fatty acid. Free fatty acid is generated due to action of the lysophospholipase to LPA. A phospholipid derivative known as LPA can function as a signaling molecule. A glycerol backbone serves as the foundation for phosphatidic acid, which also has bonds to an unsaturated fatty acid at carbon-1, a hydroxyl group at carbon-2, and a phosphate molecule at carbon-3. Free fatty acid and glycerol-3-phosphate are formed when LPA reacts with lysophospholipase. The formation of free fatty acid depends on the concentration of LPA. The standard graph of known concentrations of LPA, LPA spiked serum and LPA spiked plasma was plotted. The concentration of LPA in unknown serum and plasma were calculated from the standard graph. The limit of detection of LPA in spiked serum and plasma samples via titrimetric assay was calculated as 0.156 μmol/L. A patient's chance of survival may be outweighed by an early diagnosis of ovarian cancer.
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Affiliation(s)
- Nazia Tarannum
- Department of Chemistry, Chaudhary Charan Singh University, Meerut, India
| | - Deepak Kumar
- Department of Chemistry, Chaudhary Charan Singh University, Meerut, India
| | - Ranu Agrawal
- Department of Applied Science, Sir Chhotu Ram Institute of Engineering and Technology, Chaudhary Charan Singh University, Meerut, India
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6
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Ahmad M, Ahmad A, Omar TFT, Mohammad R. Current Trends of Analytical Techniques for Total Alkalinity Measurement in Water Samples: A Review. Crit Rev Anal Chem 2023:1-11. [PMID: 37052389 DOI: 10.1080/10408347.2023.2199432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
Increasing acidity of seawater caused by increasing anthropogenic carbon dioxide absorbed into the seawater attracted the interest of researchers due to increased concern on the deterioration of marine systems and food supply to humans. Total alkalinity (TA) is one of the important parameters in determining carbonate chemistry and is described as the capacity of the sample to neutralize acids. Over the last two decades, many analytical techniques have been developed to determine TA. This article presents a review of different analytical techniques including titration, colorimetric, spectrophotometric, and potentiometric analyses in measuring TA. Among these analytical techniques, potentiometry analysis, which utilizes electrode systems such as glass electrode and ion-selective electrode used as indicator electrodes, is the most used technique. Important features such as principle, limitations, and challenges of the involved technique are discussed in detail.
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Affiliation(s)
- Mariani Ahmad
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Terengganu, Malaysia
| | - Azrilawani Ahmad
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Terengganu, Malaysia
- Ocean Pollution and Ecotoxicology Research Group, Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Terengganu, Malaysia
| | - Tuan Fauzan Tuan Omar
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Terengganu, Malaysia
- Ocean Pollution and Ecotoxicology Research Group, Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Terengganu, Malaysia
| | - Rosmawani Mohammad
- Faculty of Bioengineering and Technology, Jeli Campus, Universiti Malaysia Kelantan, Kelantan, Malaysia
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7
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Chen C, Wiorek A, Gomis-Berenguer A, Crespo GA, Cuartero M. Portable All-in-One Electrochemical Actuator-Sensor System for the Detection of Dissolved Inorganic Phosphorus in Seawater. Anal Chem 2023; 95:4180-4189. [PMID: 36724079 PMCID: PMC9979141 DOI: 10.1021/acs.analchem.2c05307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We present a methodology for the detection of dissolved inorganic phosphorous (DIP) in seawater using an electrochemically driven actuator-sensor system. The motivation for this work stems from the lack of tangible solutions for the in situ monitoring of nutrients in water systems. It does not require the addition of any reagents to the sample and works under mild polarization conditions, with the sample confined to a thin-layer compartment. Subsequent steps include the oxidation of polyaniline to lower the pH, the delivery of molybdate via a molybdenum electrode, and the formation of an electroactive phosphomolybdate complex from DIP species. The phosphomolybdate complex is ultimately detected by either cyclic voltammetry (CV) or square wave voltammetry (SWV). The combined release of protons and molybdate consistently results in a sample pH < 2 as well as a sufficient excess of molybdate, fulfilling the conditions required for the stoichiometric detection of DIP. The current of the voltammetric peak was found to be linearly related to DIP concentrations between 1 and 20 μM for CV and 0.1 and 20 μM for SWV, while also being selective against common silicate interference. The analytical application of the system was demonstrated by the validated characterization of five seawater samples, revealing an acceptable degree of difference compared to chromatography measurements. This work paves the way for the future DIP digitalization in environmental waters by in situ electrochemical probes with unprecedented spatial and temporal resolution. It is expected to provide real-time data on anthropogenic nutrient discharges as well as the improved monitoring of seawater restoration actions.
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Affiliation(s)
- Chen Chen
- Department
of Chemistry, School of Engineering Science in Chemistry, Biochemistry
and Health, KTH Royal Institute of Technology, SE-100 44Stockholm, Sweden
| | - Alexander Wiorek
- Department
of Chemistry, School of Engineering Science in Chemistry, Biochemistry
and Health, KTH Royal Institute of Technology, SE-100 44Stockholm, Sweden
| | - Alicia Gomis-Berenguer
- Department
of Chemistry, School of Engineering Science in Chemistry, Biochemistry
and Health, KTH Royal Institute of Technology, SE-100 44Stockholm, Sweden
| | - Gaston A. Crespo
- Department
of Chemistry, School of Engineering Science in Chemistry, Biochemistry
and Health, KTH Royal Institute of Technology, SE-100 44Stockholm, Sweden,UCAM-SENS,
Universidad Católica San Antonio de Murcia, UCAM HiTech, Avda. Andres Hernandez Ros 1, 30107Murcia, Spain
| | - Maria Cuartero
- Department
of Chemistry, School of Engineering Science in Chemistry, Biochemistry
and Health, KTH Royal Institute of Technology, SE-100 44Stockholm, Sweden,UCAM-SENS,
Universidad Católica San Antonio de Murcia, UCAM HiTech, Avda. Andres Hernandez Ros 1, 30107Murcia, Spain,
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8
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Steininger F, Wiorek A, Crespo GA, Koren K, Cuartero M. Imaging Sample Acidification Triggered by Electrochemically Activated Polyaniline. Anal Chem 2022; 94:13647-13651. [PMID: 36166620 PMCID: PMC9558083 DOI: 10.1021/acs.analchem.2c03409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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In this letter, we demonstrate 2D acidification of samples
at environmental
and physiological pH with an electrochemically activated polyaniline
(PANI) mesh. A novel sensor–actuator concept is conceived for
such a purpose. The sample is sandwiched between the PANI (actuator)
and a planar pH optode (sensor) placed at a very close distance (∼0.50
mm). Upon application of a mild potential to the mesh, in contrast
to previously reported acidification approaches, PANI releases a significant
number of protons, causing an acid–base titration in the sample.
This process is monitored in time and space by the pH optode, providing
chemical imaging of the pH decrease along the dynamic titration via
photographic acquisition. Acidification of samples at varying buffer
capacity has been investigated: the higher the buffer capacity, the
more time (and therefore proton charge) was needed to reach a pH of
4.5 or even lower. Also, the ability to map spatial differences in
buffer capacity within a sample during the acid–base titration
was unprecedentedly proven. The sensor–actuator concept could
be used for monitoring certain analytes in samples that specifically
require acidification pretreatment. Particularly, in combination with
different optodes, dynamic mapping of concentration gradients will
be accessible in complex environmental samples ranging from roots
and sediments to bacterial aggregates.
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Affiliation(s)
- Fabian Steininger
- Aarhus University Centre for Water Technology, Department of Biology, Section for Microbiology, Aarhus University, 8000 Aarhus, Denmark
| | - Alexander Wiorek
- Department of Chemistry, School of Engineering Science in Chemistry, Biochemistry and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Gaston A Crespo
- Department of Chemistry, School of Engineering Science in Chemistry, Biochemistry and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Klaus Koren
- Aarhus University Centre for Water Technology, Department of Biology, Section for Microbiology, Aarhus University, 8000 Aarhus, Denmark
| | - Maria Cuartero
- Department of Chemistry, School of Engineering Science in Chemistry, Biochemistry and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
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