Detection Limit For Determination Research Articles

SWCNT fibers decorated with Au nanoparticles as voltammetric sensors for arsenic (III) determination

We developed a new method to produce fiber electrodes from single-walled carbon nanotube (SWCNT) films, which can be employed as a novel sensing platform for electrochemical investigations and analysis. By assembling SWCNT bundles in the form of a strong free-standing fiber with almost entire surface accessible to an analyte, we are able to avoid the interference of substrate and improve detection efficiency. We examined the influence of physical, chemical and electrochemical pretreatments of the new electrode SWCNT material on its properties. Transmission and scanning electron microscopy, Raman spectroscopy and cyclic voltammetry were used to characterize the SWCNT fibers. The modification of the SWCNT fiber electrode with gold nanoparticles provides the necessary analytical characteristics including high repeatability and sensitivity and low detection limit (1.3 – 2.1 μg L-1) for arsenic determination by anodic stripping voltammetry. Arsenic detection parameters such as deposition potential, deposition time and scan rate were optimized. Linear responses were found in concentration ranges from 3 to 210 μg L-1 and 7 to 125 μg L-1 for gold modified SWCNT fiber sensors (the SWCNTs were synthesized using CO or ethanol as precursors) at a relatively low deposition time of 60 s. The developed Au-SWCNT sensors allow rapid As determination in real samples and exhibit high durability and long service life.

Determination of 3-(4-hydroxyphenyl)lactic acid by an amperometric sensor with molecularly imprinted polymers

Sepsis is a life-threatening organ dysfunction caused by the dysregulation of the body’s response to infection. If sepsis is not diagnosed early and treated, it can lead to septic shock, multi-organ failure, and death. The diagnosis of sepsis, traditionally relying on clinical findings and detection of aetiologically significant microorganisms in the blood and foci, has been improved in recent years by the search for and implementation of various biomarkers. One promising biomarker of sepsis is 3-(4-hydroxyphenyl)lactic acid (HPLA). In this study, we developed an amperometric sensor modified with a molecularly imprint polymer (MIP) of hydroxyphenyl lactic acid and proved the fundamental possibility of determining HPLA by this sensor in model aqueous solutions. Molecularly imprinted polymers are widely used to separate substances and to produce selective sensors. Among the variety of selective materials, polyimides are of particular interest. Therefore, in this study, we developed MIP sensors imprinted with 4-hydroxyphenyl lactic acid on the basis of copolymer of 1,2,4,5-benzoltetracarboxylic acid with 4,4'-diaminodiphenyloxide. The sensors were prepared in two stages (1st stage at 80°С, 2nd stage at 180°С) by non-covalent imprinting method. High selectivity of PMO-sensors towards target molecules was confirmed. The range of the determined concentrations of the acid was 0.2-0.0002 mg/dm3. The experimentally determined detection limit of 4-hydroxyphenyl lactic acid was 4.5·10-5 mg/dm3.

Construction of a dual-signal readout platform for effective glutathione S-transferase sensing based on polyethyleneimine-capped silver nanoclusters and cobalt-manganese oxide nanosheets with oxidase-mimicking activity.

Anovel dual-mode fluorometric and colorimetric sensing platform is reported for determining glutathione S-transferase (GST) by utilizing polyethyleneimine-capped silver nanoclusters (PEI-AgNCs) and cobalt-manganese oxide nanosheets (CoMn-ONSs) with oxidase-like activity. Abundant active oxygen species (O2•-) can be produced through the CoMn-ONSs interacting with dissolved oxygen. Afterward, the pink oxDPD was generated through the oxidation of colorless N,N-diethyl-p-phenylenediamine (DPD) by O2•-, and two absorption peaks at 510 and 551nm could be observed. Simultaneously, oxDPD could quench the fluorescence of PEI-AgNCs at 504nm via the inner filter effect (IFE). However, in the presenceof glutathione (GSH), GSH prevents the oxidation of DPD due to the reducibility of GSH, leading to the absorbance decreaseat 510 and 551nm. Furthermore, the fluorescence at 504nm was restored due to the quenching effect of oxDPD on decreasedPEI-AgNCs. Under the catalysis of GST, GSH and1-chloro-2,4-dinitrobenzo (CDNB) conjugate to generate an adduct, initiating the occurrence of the oxidation of the chromogenic substrate DPD, thereby inducing a distinct colorimetric response again and the significant quenching of PEI-AgNCs. The detection limits for GST determination were 0.04 and 0.21 U/L for fluorometric and colorimetric modes, respectively. Thesensing platform illustrated reliable applicability in detecting GST in real samples.

β-Glucuronidase-triggered reaction for fluorometric and colorimetric dual-mode assay based on the in situ formation of silicon nanoparticles

Backgroundβ-Glucuronidase (GUS) is considered as a promising biomarker for primary cancer. Thus, the reliable detection of GUS has great practical significance in the discovery and diagnosis of cancer. Compared with traditional organic probes, silicon nanoparticles (Si NPs) have emerged as robust optical nanomaterials due to their facile preparation, superior photobleaching resistance and excellent biocompatibility. However, most nanomaterials-based methods only output a single signal which is easily influenced by external factors in complex systems. Hence, developing nanomaterial-based multi-signal optical assays for highly sensitive GUS determination is still urgently desired. ResultsIn this study, we developed a simple and efficient one-step method for the in situ preparation of yellow color and yellow-green fluorescent Si NPs. This was achieved by combining 3-[2-(2-aminoethylamino) ethylamino] propyl-trimethoxysilane with p-aminophenol (AP) in an aqueous solution. The obtained Si NPs showed yellow-green fluorescence at 535 nm when excited at 380 nm, while also exhibiting an absorption peak at a wavelength of 490 nm. Taking inspiration from the easy synthesis step regulated by AP, which is generated through the hydrolysis of 4-aminophenyl β-D-glucuronide catalyzed by GUS, we constructed a direct fluorometric and colorimetric dual-mode method to measure GUS activity. The developed fluorometric and colorimetric sensing platform showed high sensitivity and accuracy with detection limits for GUS determination as low as 0.0093 and 0.081 U/L, respectively. SignificanceThis study provides a facile dual-mode fluorometric and colorimetric approach for determination of GUS activity based on novel Si NPs for the first time. This designed sensing approach was successfully employed for the quantification of GUS in human serum samples and screening of GUS inhibitors, indicating the feasibility and potential applications in clinical cancer diagnosis and anti-cancer drug discovery.

The graphene quantum dots encased in the molecularly imprinted polymer as a new fluorescent nanosensor for the detection of biotin

In aqueous solution, a non-toxic fluorescent nanosensor incorporating graphene quantum dots encased in molecularly imprinted polymer (GQDs-encased in MIP) is manufactured through a straightforward sol-gel process. During the polymerization process, the functional monomer 3-aminopropyltriethoxysilane (APTES) and the cross-linker tetraethyl orthosilicate (TEOS) were utilized to bind the biotin in a polymer network. The resulting GQDs@MIP nanocomposite outperformed the similar non-imprinted polymer (GQDs-encased in NIP) in terms of biotin selectivity. Under ideal conditions, the produced GQD-encased in MIP are employed to detect biotin by quenching their fluorescence caused by the target analyte via photo induced electron transfer (PET). The quenching curves of each GQDs-encased in polymer were fitted with the Stern-Volmer-type equation, and GQDs-encased in MIP had a broader linear range and a lower limit of detection than GQDs-encased in NIP. GQDs-encased in MIP fluorescence response is linear with respect to biotin concentration over a wide linear range of at least 0.4 μmol L−1 to 6.7 μmol L−1. The detection limit for biotin determination was 315 nmol L−1. The suggested GQDs-encased in MIP is promising for the measurement of trace biotin in human serum samples because to its non-toxicity, simplicity, and low cost, as well as its strong analytical performance.

A Review of Analytical Methods and Technologies for Monitoring Per- and Polyfluoroalkyl Substances (PFAS) in Water

Per- and polyfluoroalkyl substances (PFAS) consist of a range of manufactured fluorinated chemicals that are used in a variety of household and waterproofing products, industrial processes, and firefighting foams. In the past few years, there has been increasing concern about PFAS in the environment, since they are difficult to break down through natural processes, are highly persistent in humans, animals, soils and waters, and can travel long distances in surface and groundwater. This has created an increased need for PFAS analysis. Most PFAS monitoring currently takes place using field sampling and chromatographic analytical methods, which are laboratory-based and are very costly when used to monitor PFAS in the environment. Using a semi-systematic literature review approach, a comparative study is conducted in this article on the available analytical methods and sensor technologies that can be used to monitor and detect PFAS in the environment, including chromatographic, instrumentation analysis, and sensor-based methods. This study considered four critical factors for effective and efficient monitoring methods, which include the type of PFAS detected, removing background levels, determining detection limits, and identifying samples. In general, other analytical instruments are used in conjunction with chromatographic techniques for detecting both target and non-target analytes at a lower level of detection (LOD). It is shown that even though some sensor types have a low LOD, they are only useful for detecting targeted PFAS in water samples. However, sensors are an emerging technology that could be developed to enable low-cost, portable methods for the remote detection of PFAS species on-site.

Disposable nanosensor for the electrochemical determination of the interaction between DNA, and a mycotoxin, patulin

Silicon dioxide nanoparticles were synthesized and disposable screen-printed electrodes were modified with these nanoparticles to electrochemically detect the interaction between DNA and patulin, a mycotoxin. Firstly, the synthesized silicon dioxide nanoparticles were chemically characterized by X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). Microscopic characterization of the nanoparticles was performed by Transmission Electron Microscopy (TEM) and Energy-dispersive X-ray spectroscopy (EDX). The surface of the silicon dioxide nanoparticle-modified screen-printed electrode was characterized by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). SiNP modification resulted in a 2-fold increase in surface area and a 2.3-fold enhancement in the signal. The detection limit (LOD) for the electrochemical patulin determination was calculated as 1.15 µg/mL, and the linear concentration range was found to be 3.2–20 µg/mL. The mode of interaction between patulin and dsDNA was determined through a molecular docking study. After the interaction between patulin and dsDNA, approximately 86 % and 23 % decreases were observed in patulin and guanine oxidation signals, respectively. The S % value for patulin was calculated by utilizing the decrease in the guanine signal after the interaction.

Determination of Cd, Pb and Zn in Polymers by Laser Ablation Microwave Induced Plasma Optical Emission Spectrometry

Abstract The potential of laser ablation microwave induced plasma optical emission spectrometry (LA-MIP OES) for the analysis of plastic materials has been investigated. Inorganic species, e.g., metals may be added to them as additives, anti-oxidising agents, stabilisers, plasticisers, colorants and catalytic residues, contaminants and may be present in a wide range of concentrations. The study revealed elevated content of trace elements (Cd, Pb and Zn) which are components of poly(vinyl chloride) (PVC) and polyethylene (PE). Laser ablation using wavelengths of 266 nm as a sampling method for MIP OES was used. The result achieved using elaborated system were compared with those obtained after polymer samples decomposition in high pressure-temperature focused microwave heating digestion system and standard sample pneumatic nebulisation (PN) to MIP OES spectrometer. The calibration strategy using cellulose pellets as support for qualitative analysis for element determination in polymers by LA-MIP OES was proposed. This analytical performance of the LA-MIP OES system was characterised by a determination of the limits of detection (LODs) and precision (RSDs) for elements tested. The experimental concentration detection limits for simultaneous determination, calculated as the concentration giving a signal equal to three times of the standard deviation of the blank (LOD, 3σblank criterion, peak height) were 2 µg g– 1, 3 µg g– 1 and 5 µg g– 1 for Cd, Pb and Zn, respectively. The method offers relatively good precision (RSD ranged from 3 % to 5 %) for micro sampling analysis.

The use of aromatic aldehydes for the test determination of cefotaxime

Indicator papers based on immobilized reagents with their subsequent digital image processing are widely used for the quick and cheap screening study of drugs when assessing the content of the main substance in drugs for the presence of counterfeits. Indicator papers based on reagents immobilized on a cellulose matrix 4-dimethylaminocinnamic aldehyde (DMACA), 4-dimethylaminobenzaldehyde (DMAB), and 3-methoxy-4-hydroxybenzaldehyde (vanillin) were proposed for the determination of β-lactam antibiotic cefotaxime. To specify optimal conditions for the immobilization of reagents on a solid matrix, the intensities (changes in intensities) of color parameters were recorded at a different concentration of reagents, type of surfactants, and paper porosity. The detection limits of visual-colorimetric determination of cefotaxime were 1.0 mg/ml (DMACA), 0.12 mg/ml (DMAB), and 0.30 mg/ml (vanillin). Colorimetric processing of images of the test agents was carried out in the GIMP (GNU Image Manipulation Program) 2.10 program by averaging the images of indicator papers using the blur-sharp function, determining the intensity of color parameters. The photos were taken using a 48-megapixel camera of a POCO X3 pro smartphone in a specialized box measuring 22 × 23 × 24 cm with two LED lighting strips (5 V, 1 A). Linear dependences of the intensities of color parameters of the RGB, HSV, and CMYK models on the cefotaxime concentration (log c) were obtained: y = –15x + 45 (r2 = 0. 99, color parameter H for DMACA), y = –51x + 130 (r2 = = 0.99, parameter B for DMAB), y = 36x + 30 (r2 = 0. 99, S parameter for vanillin). Linear dependences of the areas and perimeters of the petal diagrams of indicator papers on the cefotaxime concentration have been plotted for the studied systems of cefotaxime — immobilized reagent. The correctness of the determination results was assessed using the analysis of spiked samples, the relative error did not exceed 25%. The developed test tools based on immobilized aromatic aldehydes are recommended for the semi-quantitative determination of cefotaxime.

Microextraction of Tigecycline Using Deep Eutectic Solvents and Its Determination in Milk by LC-MS/MS Method.

The occurrence of tigecycline (TGC), a new first glycylcycline antibiotic residues in food products harmfully influences potential human consumers health. Therefore, analysts are forced to develop new microextraction methods connected with modern extractants for effective isolation of this compound. For this purpose, deep eutectic solvents (DES) as the extraction media were used. Liquid-liquid microextraction (LLME) of tigecycline from milk samples with application of the hydrophobic deep eutectic solvents: decanoic acid:thymol (1:1), thymol:camphor (2:1), dodecanoic acid:menthol (2:1), and dodecanoic acid:dodecanol (1:1) was developed. The studied samples were subjected to a deproteinization process using trichloroacetic acid solution and acetonitrile. The optimal microextraction parameters, molar ratio of DES components, amount of extraction solvents, pH of milk sample, shaking, and centrifugation time, were chosen. Tigecycline in the obtained microextracts of deep eutectic solvents was analyzed using a liquid chromatographic technique connected with a tandem mass spectrometry (LC-MS/MS) system. The limits of detection and quantification values for TGC determination followed by DES-LLME-LC-MS/MS method were in the 1.8 × 10-11 mol L-1 (0.01 μg kg-1) to 4.0 × 10-9 mol L-1 (2.28 μg kg-1) and 5.5 × 10-11 mol L-1 (0.03 μg kg-1) to 1.2 × 10-8 mol L-1 (6.84 μg kg-1) ranges, respectively. The RSD values of precision were in the range 1.4-7.8% (intraday) and 5.4-11.7% (interday). The developed procedures were used for the determination of tigecycline in different bovine milk samples.

Double deposition/accumulation and double stripping steps system as a new way of decreasing the detection limit and elimination of interferences in stripping voltammetry of inorganic ions: A review

AbstractThe article reviews an application of double deposition/accumulation and stripping steps as a new and beneficial manner of decreasing a detection limit and/or interferences elimination in stripping voltammetric determination of inorganic ions: Pb(II), Cd(II), Tl(I), U(VI), Au(III), As(III), Se(IV), In(III), Co(II), Cu(II), Bi(III) and Ga(III). A simple design of four‐electrodes system, containing two working electrodes differing in their surface area, allows for conducting two preconcentration and two stripping steps in one measurement cycle and in one voltammetric cell. Considerable analytes preconcentration and, consequently, an increase of sensitivity of determinations was obtained by conducting the first stripping step in a small volume of a solution near the microelectrode surface. An appropriate selection of the conditions of the first deposition/accumulation and the first stripping steps allowed for a minimization/elimination of interference effects. The proposed procedures allows for ultra‐trace levels determinations of mentioned inorganic ions (often impossible to determine by means of traditional three‐electrodes systems) without additional preconcentration outside the electrochemical cell and with the use of mercury‐free electrodes.

Drinking water as a substantial source of toxic alkali, alkaline and heavy metals: Toxicity and their implications on human health

ObjectivesThe objective of the current study was to optimize a highly sensitive method utilizing microwave digestion and iCAP quadrupole inductively coupled plasma mass spectrometry (Q ICP-MS) for the determination of toxic alkali, alkaline and heavy metals in drinking water, and their implications on human health. MethodsA highly sensitive method based on microwave digestion and iCAP Q ICP-MS have been applied for the determination of potential metals alkali (23Na), alkaline (24 Mg) and heavy metals (75As, 208Pb, 111Cd, 59Co, 66Zn and 63Cu) in drinking water of diverse brand and origin. ResultsThe system has provided excellent quality conditions, such as detection limit (DL, 0.007–0.296 µg/L), quantification limit (QL, 0.023–0.893 µg/L) and coefficient of determination (R2, 0.976–0.998) with recovery >99.95%. Amounts of metals in bottled drinking water (BDW) were ranged from not detected to 74847.15 µg/L, whereas, tap water (TW) constitutes 1.12 to 42776.89 µg/L. Average daily dose (ADD, 0.03–516.715 μg/kg/day), hazard quotient (HQ, 0.001–0.08 μg/kg/day) based on heavy metals oral reference dose, and cancer risk (CR, 0.45–244.67 μg/kg/day) based on heavy metals cancer slope factor were achieved for BDW. Nevertheless, ADD (0.03–1028.19 μg/kg/day), HQ (0.01–0.12 μg/kg/day) and CR (0.42–292.80 μg/kg/day) were obtained for TW. As a result, BDW produced lower toxicity values than TW (high risk). Additionally, BDW was found to be brand specific, particularly for international brands that contained zero or very low levels of metals. ConclusionsCurrent investigations have explored the possible impacts of progressively increasing consumption of drinking water, especially in Saudi Arabia. Up to the present time, the levels of potential heavy metal in such water pose predominantly higher toxicity values in TW. Besides, BDW was found to be the brand specific particularly the international brand which contained either zero or low level of metals. As a result, the results highlight the need for strict policies to address the threat of metals in public water.

Applying smartphone camera, spectrophotometry, or ocular analysis-based dipsticks for the detection of glutathione level as a cancer biomarker

This study provides simple sensitive and selective spot tests and spectrophotometric methods for quantifying l-glutathione (GSH) as a cancer biomarker. The dipsticks are based on filter paper containing a Cu(II)-murexide complex which was prepared in phosphate buffer pH 6.0 and then incorporated inside a filter paper matrix. On addition of GSH, the spots' color progressively changed from yellow to orange through pink to violet before gradually vanishing. The indicator is released when GSH is injected because GSH displaces murexide dye from the murexide-Cu2+ complex. This enables the determination of glutathione in human serum visually using the reflectometric Red-Green-Blue (RGB) interpretation of the dipstick image data. In the spectrophotometric method, the Cu2+-murexide complex absorbance band is gradually red-shifted upon interaction with different concentrations of glutathione due to the displacement reaction.Glutathione can be determined from 0.01 to 500 μg mL−1 visually and from the evaluation of the smartphone images. The limit of detection for glutathione determination using dipsticks is 0.01 μg mL−1, which is the lowest value to date. This technique has been successfully used with positive outcomes to identify low concentrations of glutathione in samples of human serum.

Bright Green Light-Emitting Gold Nanoclusters Confined in Insulin as Selective Fluorescent Switch Probes for Sensing and Imaging of Copper Ions and Glutathione

In this study, an on–off–on fluorescence probe is developed for rapid, sensitive, and selective detection of Cu2+ ions and glutathione (GSH) based on green light-emitting insulin-capped gold nanoclusters (Ins/Au-NCs). Ins/Au-NCs with low toxicity and excellent stability were prepared by utilizing a simple and green strategy. Cu2+ ions can selectively decrease the fluorescence intensity of Ins/Au-NCs by an aggregation-caused quenching mechanism, which can be recovered in the presence of GSH. Under the optimized condition, the detection limits for determination of Cu2+ ions and GSH are estimated as 7.5 and 9.2 nM, with linear ranges of 0.05 to 1.7 μM and 0.05 to 1.5 μM, respectively. Chemical modeling was also employed to investigate the interaction of the Ins/Au-NCs probe with Cu2+, Hg2+, glutathione, and cysteine. The calculated molecular orbital energy well confirmed the experimental selective results obtained. Luminescence cellular imaging exhibited a sensitive response of the Ins/Au-NCs probe toward Cu2+ ions in breast cancer cells MCF-7, and thus, it potentially acted as an intracellular GSH probe in MCF-7 compared to the human fibroblast HFF cells. The as-prepared probe was successfully applied to low levels of Cu2+ ions and GSH in water and human serum samples. The designed Ins/Au-NCs-based probe may also provide a biocompatible platform for label-free GSH detection in biological and clinical implications that comprise staining and early prevention of cancer, AIDS, and Alzheimer’s and cardiovascular diseases.

Oxygen vacancies rich Co-Mo metal oxide microspheres as efficient oxidase mimetic for colorimetric detection of sulfite

Modulation of surface oxygen vacancies (Ov) by defect engineering is an attractive strategy for designing high performance transition metal oxide nanozymes. In this work, we reported the fabrication of the CoMoO4 oxidase-like nanozyme, i.e. CoMo-300r, by first pyrolyzing the CoMo layered double hydroxide precursor in an air atmosphere at 300 °C and subsequent NaBH4 reduction strategy. Various characterization outcomes confirm the mesoporous structures of both CoMo-300r and no NaBH4 treated CoMo-300, while the specific surface area of CoMo-300 is significantly increased from 103.54 m2·g−1 to 165.24 m2·g−1 after NaBH4 reduction. Also, NaBH4 reduction treatment leads to the formation of Ov rich CoMoO4 and reduced metal ion species on the surface, promoting the redox reaction kinetics. The CoMo-300r prepared at a molar ratio of Co to Mo of 1:2, pyrolysis temperature of 300 °C and 10 mM NaBH4 exhibited the best oxidase-like activity. The oxidase-like activity of CoMo-300r is 2.6-fold times that of no NaBH4 treated optimal CoMo-300. The CoMo-300r can effectively promote TMB oxidation to produce blue color and has the Michaelis-Menten constant of 0.0428 mM, which was lower than most cobalt-based oxide nanozymes and indicated a higher affinity for TMB. In terms of inhibition of SO32− on the CoMo-300r/TMB system, a sensitive SO32− colorimetric sensing platform was established. The linear range and limit of detection for sulfite determination were 0.2–40 μM and 0.09 μM, respectively. The relative standard deviation for the determination of 10 μM sulfite was 1.41% (n = 11). The method was successfully applied to the detection of sulfite in white wine. This work provides a new strategy to fabricate high activity oxidase mimetic for food analysis.

A novel atropine electrochemical sensor based on silver nano particle-coated Spirulina platensis multicellular blue-green microalga

In this work, Atropine as the anticholinergic drug was measured using the environmentally friendly sensor. In this regard, Self-cultivated Spirulina platensis with electroless silver was employed as a powder amplifier in carbon paste electrode modification. Also, 1-Hexyl-3 methylimidazolium Hexafluorophosphate (HMIM PF6) ion liquid as a conductor binder was used in the suggested electrode construction. Atropine determination was investigated by voltammetry methods. According to voltammograms, the electrochemical behavior of atropine depends on pH, and pH 10.0 was used as the optimal condition. Moreover, the diffusion control process for the electro-oxidation of atropine was verified by the scan rate study, so the diffusion coefficient (D∼ 3.0136×10−4cm2/sec) value was computed from the chronoamperometry study. Furthermore, responses of the fabricated sensor were linear in the concentration range from 0.01 to 800 μM, and the lowest detection limit of the Atropine determination was obtained at 5 nM. Moreover, the stability, reproducibility, and selectivity factors of the suggested sensor were confirmed by the results. Finally, the recovery percentages for atropine sulfate ampoule (94.48–101.58), and water (98.01–101.3) approve of the applicability of the proposed sensor to Atropine determination in real samples.

Sensitive adsorptive stripping voltammetric procedure of Imatinib determination in spiked urine samples using solid lead microelectrode

AbstractThis article reports for the first time the application of solid lead microelectrode for organic compound determination. The proposed sensor was used for anticancer drug Imatinib quantification by adsorptive stripping voltammetry. Procedure of Imatinib determination was developed utilizing advantages ensured by solid lead microelectrode: reusability and durability for a long period of time and its ecological character as compared to film electrodes. The detection limit of Imatinib determination was calculated to be 1.9 × 10−10 mol L−1. The analytical usability of the developed procedure was confirmed by acceptable recoveries of Imatinib determination in spiked urine samples.

Luminescent Metal-Organic Framework with 2,1,3-Benzothiadiazole Units for Highly Sensitive Gossypol Sensing

A new metal–organic framework based on cadmium(II) cations, di(p-carboxyphenyl)sulphone and 4,7-di(imidazol-1-yl)-2,1,3-benzothiadiazole was prepared, and its crystal structure was determined using single-crystal XRD analysis. MOF demonstrated bright luminescence with a maximum near 500 nm and quantum yield reaching 20%. In addition, this MOF demonstrated sensing properties towards antibiotics and a toxic natural polyphenol gossypol through effective luminescence quenching in an ethanol suspension. The determined detection limit for gossypol was among the lowest reported so far (0.65 µM), and did not significantly change in the interference experiments with cottonseed oil as background, indicating the possibility of using this MOF as a sensor for the detection and determination of gossypol in real-life samples.

Two new manganese-based phosphomolybdate compounds as electrochemical sensors for the highly sensitive trace determination of heavy metal Cr(vi) ions

Two manganese-based phosphomolybdate compounds 1–2 have been prepared by hydrothermal method. Compound 1–2 are used as electrochemical sensors with a low limits of detection and good selectivity for trace determination of Cr(vi) ions.

A novel potentiometric sensor based on ZnO decorated polyaniline/coal nanocomposite for diltiazem determination.

Diltiazem (DTZ) is one of the most effective medications for treating cardiovascular diseases. It has been widely used for the treatment of angina pectoris, hypertension and some types of arrhythmia. The development and application of a modified carbon paste sensor with improved detection limits for the potentiometric determination of diltiazem are the main goals of the current study. Sensitivity, long-term stability, reproducibility and improving the electrochemical performance are among the characteristics that have undergone careful examination. A modified carbon paste sensor based on β-cyclodextrin (β-CD) as ionophore, a lipophilic anionic additive (NaTPB) and a ZnO-decorated polyaniline/coal nanocomposite (ZnO@PANI/C) dissolved in dibutyl phthalate plasticizer, exhibited the best performance and Nernstian slope. The ZnO@PANI/C based sensor succeeded in lowering the detection limit to 5.0 × 10-7 through the linear range 1.0 × 10-6 to 1.0 × 10-2 mol L-1 with fast response time ≤ 10.0 s. The prepared nanomaterial was characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The surface properties of the proposed sensor were characterized by electrochemical impedance spectroscopy (EIS). The selectivity behavior of the investigated sensor was tested against a drug with similar chemical structure and biologically important blood electrolytes (Na+, K+, Mg2+, and Ca2+). The proposed analytical method was applied for DTZ analysis in pure drug, pharmaceutical products and industrial water samples with excellent recovery data.