Real Environmental Samples Research Articles

Magnetic ZIF-8-Based Mimic Multi-enzyme System as a Colorimetric Biosensor for Detection of Aryloxyphenoxypropionate Herbicides.

In the present study, a magnetic mimic multi-enzyme system was developed by encapsulating the aryloxyphenoxypropionate (AOPP) herbicide hydrolase QpeH and alcohol oxidase (AOx) in zeolitic imidazolate framework (ZIF-8) nanocrystals with magnetic Fe3O4 nanoparticles (MNPs) to detect AOPP herbicides. The structural, protein loading capacity and loading ratio, porosity, and magnetic properties of QpeH/AOx@mZIF-8 were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, nitrogen sorption, and vibrating sample magnetometry. An AOPP herbicide colorimetric biosensor made with QpeH/AOx@mZIF-8 had the highest sensitivity toward quizalofop-P-ethyl (QpE) with a limit of detection of 8.2 μM. This system was suitable to detect two other AOPP herbicides, including fenoxaprop-P-ethyl (FpE) and haloxyfop-P-methyl (HpE). The practical application of the biosensor was verified through quantitative analysis of QpE residues in industrial wastewater and field soils. Furthermore, QpeH/AOx@mZIF-8 exhibited excellent long-term storage stability (at least 50 days), easy separation by magnet, and reusability (at least 10 cycles), supporting its promising role in simple and low-cost detection of AOPP herbicides in real environmental samples.

A label-free ratiometric method to detect Hg2+ based on structural change of DNA.

In this work, a simple ratiometric method has been designed to detect Hg2+ based on the structural change between double-stranded DNA (dsDNA) and its G-quadruplex structure. When Hg2+ was added, the designed G-quadruplex structure could change into the corresponding dsDNA by forming the T-Hg2+ -T mismatch. This kind of variation resulted in a decrease in the fluorescence of the G-quadruplex/N-methyl mesoporphyrin IX (NMM) complex and an increase in the fluorescence from the dsDNA/SYBR Green I (SG I) pair. The secondary excitation wavelength of SG I was used to excite NMM and SG I simultaneously. The titration experiment indicated that the new method had a linear response within 0.7-2.5 μM Hg2+ with a limit of detection of 9.3 nM. Because using the T-Hg2+ -T mismatch to recognize Hg2+ was very specific, the selectivity of the new method was also satisfactory. The recoveries ranged from 92.8% to 110.2% suggested that this new method could achieve a potential application for Hg2+ detection in real environmental samples.

Facile synthesis of chitosan-carbon nanofiber composite supported copper nanoparticles for electrochemical sensing of carbendazim

The detection of carbendazim (CBZ) is very important due to environmental concern. Hence, the development of efficient electrocatalytic sensors for CBZ is of great interest to researchers. In this work, chitosan-functionalized carbon nanofiber composites were prepared onto which Cu nanoparticles were immobilized (abbreviated as CT-fC-Cu nanocomposites) via a simple sonication approach. The as-prepared CT-fC-Cu nanocomposites were first characterized and then they were fabricated on screen-printed carbon electrode (SPCE) for electrochemical measurements of CBZ by cyclic voltammetry (CV). The electrochemical sensing of biocompatible CT-fC-Cu/SPCE towards CBZ was studied using linear sweep voltammetry (LSV). As expected, the sensors revealed an excellent selectivity of CBZ with an extremely wide linear range of 0.8–277.0 µM where the limit of detection was observed to be 0.028 µM. Finally, the prepared electrode was successfully employed for the analysis of CBZ levels in real soil-washed water samples. • Chitosan-functionalized carbon nanofiber supported Cu particles (CT-fC-Cu) were synthesized. • The fabricated CT-fC-Cu electrode was applied to the electrochemical determination of CBZ. • CT-fC-Cu/SPCE shows a wide linear range, a lower detection limit, and an excellent selectivity. • The biocompatible CT-fC-Cu/SPCE can determine CBZ levels in real environmental samples.

Simultaneous electrochemical determination of nitrophenol isomers based on macroporous carbon functionalized with amino-bridged covalent organic polycalix[4]arenes

A glassy carbon electrode (GCE) modified by a hybrid, macroporous carbon (MPC) functionalized with triazine bridged covalent organic polycalix[4]arenes (CalCOP) (CalCOP-MPC), has been fabricated and utilized for simultaneous detection of nitrophenols (NP). The obtained CalCOP-MPC were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), which confirmed that MPC had functionalized with CalCOP successfully. Benefiting from the synergistic supramolecular effect of macrocyclic receptor of CalCOP and the excellent electrical properties of MPC, the anodic peaks of o-nitrophenol (o-NP), m-nitrophenol (m-NP), and p-nitrophenol (p-NP) in their mixture can be well separated by the prepared electrode. Differential pulse voltammetry (DPV) measurements at CalCOP-MPC/GCE revealed that the linear ranges of NP isomers were all 1–400 μM, and the detection limit limits were 0.383 μM, 0.122 μM, and 0.212 μM for o-NP, m-NP, and p-NP, respectively. Moreover, the prepared modified electrodes showed a relatively good selectivity and stability, implying the prospect for detecting NP in real environmental samples.

Direct identification and visualisation of real-world contaminating microplastics using Raman spectral mapping with multivariate curve resolution-alternating least squares

Microplastics (MPs) contamination is ubiquitous in environmental matrices worldwide. Moreover these pollutants can be ingested by organisms and transported to organs via the circulatory system. Although efficient methods for the analysis of MPs derived from environment matrices and organisms’ tissue samples have been developed after special sample pre-treatment, there remains a need for an optimised approach allowing direct identification and visualisation these MPs in real environmental matrices and organismal samples. Herein, we firstly used a multivariate curve resolution-alternating least squares (MCR-ALS) analysis of Raman hyperspectral imaging data to direct identification and visualisation of MPs in a complex serum background. Four common MPs types including polyethylene (PE), polystyrene (PS), polypropylene (PP) and polyethylene terephthalate (PET) were identified and visualised either individually or in mixtures within spiked samples at an 8-μm spatial resolution. Moreover, Raman imaging based on MCR-ALS was successfully applied in fish faeces biological samples and environmental sand samples for in situ MPs identification directly without washing or removal of organic matter. The current results demonstrate Raman imaging based on MCR-ALS as a novel imaging approach for direct identification and visualisation of MPs, through extraction of MPs’ chemical spectra within a complicated biological or environmental background whilst eliminating overlapping Raman bands and fluorescence interference.

A novel berberine-based colorimetric and fluorometric probe for Hg2+ detection and its applications in water samples

The development of small molecule fluorescent probes for detection of heavy metal ions is highly desirable in fluorescent sensors area, and mercury (Hg2+) is a heavy metal pollutant in environment and food chain processes. Herein, we reported the design and synthesis of a novel berberine-based fluorescent probe P1, which can specifically recognize Hg2+ in CH3OH/PBS (8:2, v/v, pH = 7.4, 10 mM) solution by the colorimetric and fluorometric changes. The probe P1 displayed high selectivity, superior sensitivity and fast response toward Hg2+ with a low detection limit and a wide range of pH values. This probe can provide a convenient and effective way for Hg2+ detection on test paper strips. Moreover, the probe P1 can be applied to quantitatively detect Hg2+ in real environmental water samples.

Reusable biosensor-based polymer dot-coated electrode surface for wireless detection of bacterial contamination

Biosensor development for bacterial detection is critical to preventing infectious disease outbreaks caused by bacterial contamination. Recent studies have focused on colorimetric sensors, but high limit of detection (LOD) has restricted their application for sensitive bacterial detection. Here, we designed a reusable, sensitive smartphone-based electrochemical biosensor which uses electroconductive boronic acid-modified polymer dot (B-PD)-coated electrode to detect bacterial contamination. The pH-selective boronic acid in B-PD promotes binding between sensor and bacteria via increased diol-diol kinetics of boronic acid at pH 7.4. B-PD-coated electrodes can detect both gram-negative (E. coli) and gram-positive (S. aureus) bacteria by observing the conductivity change after attachment (101-107 CFU/mL), with high sensitivity, as indicated by low LOD (E. coli=100.8 CFU/mL, S. aureus=101 CFU/mL). The electronic signal from bacterial detection is transmitted to smartphone by connecting B-PD-coated electrode with wireless microcontroller, which allows for simple in-line monitoring. This biosensor demonstrated excellent performance in detecting bacteria in real environmental samples, along with good selectivity towards bacteria, even in the presence of interfering compounds. Moreover, by maintaining boronic acid-diol interaction, B-PD-coated electrode can be reused after applying pH shock (pH < 6) up to four cycles. Thus, this system offers simple approach for bacteria monitoring with high sensitivity and reusability.

Environmental Odour Quantification by IOMS: Parametric vs. Non-Parametric Prediction Techniques

Odour emissions are a global issue that needs to be controlled to prevent negative impacts. Instrumental odour monitoring systems (IOMS) are an intelligent technology that can be applied to continuously assess annoyance and thus avoid complaints. However, gaps to be improved in terms of accuracy in deciphering information, especially in the implementation of the mathematical model, are still being researched, especially in environmental odour monitoring applications. This research presents and discusses the implementation of traditional and innovative parametric and non-parametric prediction techniques for the elaboration of an effective odour quantification monitoring model (OQMM), with the aim of optimizing the accuracy of the measurements. Artificial neural network (ANN), multivariate adaptive regression splines (MARSpline), partial least square (PLS), multiple linear regression (MLR) and response surface regression (RSR) are implemented and compared for prediction of odour concentrations using an advanced IOMS. Experimental analyses are carried out by using real environmental odour samples collected from a municipal solid waste treatment plant. Results highlight the strengths and weaknesses of the analysed models and their accuracy in terms of environmental odour concentration prediction. The ANN application allows us to obtain the most accurate results among the investigated techniques. This paper provides useful information to select the appropriate computational tool to process the signals from sensors, in order to improve the reliability and stability of the measurements and create a robust prediction model.

SARS-CoV-2 detection in wastewater using multiplex quantitative PCR

A multiplex reverse transcription quantitative PCR (RT-qPCR)-based method was designed for the simultaneous detection of different SARS-CoV-2 genes. In this study, we used three target genes encoding for the nucleocapsid 1 and 3 (N1, N3), and the spike (S) proteins, all commonly used in the detection of SARS-CoV-2 in human and environmental samples. The performance of the multiplex assay, compared to the single assay was assessed for the standard calibration curve, required for absolute quantification, and then, for the real environmental samples to detect SARS-CoV-2. For this latter, four environmental samples were collected at a local wastewater treatment plant (WWTP). The results showed that the cycle threshold (Ct) values of the multiplex were comparable to the values obtained by the singleplex PCR. The amplification of the three target genes indicated the presence of SARS-CoV-2 in the four water samples with an increasing trend in February and these results were confirmed in the multiplex approach, showing the robustness of this method and its applicability for the relative abundance analysis among the samples. Overall, both the laboratory and field work results demonstrated that the multiplex PCR assay developed in this study could provide a method for SARS-CoV-2 detection as robust as the single qPCR, but faster and cost-effective, reducing by three times the number of reactions, and consequently the handling time and reagents.

1′-hydroxy-2′-acetonaphthone: A simple fluorescence turn-on signaling probe with high selectivity and sensitivity for Al3+ in pure water

Adverse effects of Aluminium ion (Al3+) on human health and the environment, when present above the acceptable concentration, have stimulated much attention to its detection. Many probes are being developed to detect Al3+, most of them suffer from protracted synthesis, less aqueous solubility, and limited selectivity and sensitivity. We report a highly selective and sensitive, fluorescence turn-on sensor for Al3+ detection in pure water by employing the simple, inexpensive commercial probe, 1′-hydroxy-2′-acetonaphthone (HAN). This probe displays remarkably high ~ 120 folds fluorescence enhancement upon complexing with Al3+, the highest reported so far in an aqueous solution for Al3+ sensing. The detection limit obtained was as low as 42 nM. The huge fluorescence enhancement towards Al3+ is attributed to the chelation enhanced fluorescence (CHEF) effect and consequent impediment on the excited-state tautomeric interconversion process between keto (K*) and twisted keto (KR*) tautomers of HAN associated to its ESIPT process. This Al3+ induced inhibition in the interconversion process between K* and KR* tautomers eventually lead to the complete tautomeric arrest of KR* form of the dye complexed with Al3+, a phenomenon not reported to date for the HAN dye in any system. Notably, the present system also illustrates an efficient response towards Al3+ in tap water, suggesting the practical applicability of the current sensor system in real biological and environmental samples.

Lignin-mediated green synthesis of functionalized gold nanoparticles via pulsed laser technique for selective colorimetric detection of lead ions in aqueous media

A versatile green synthesis technique of pulsed laser irradiation and the sonochemical process was used for the production of functionalized gold nanoparticles (Au NPs) in the presence of lignin matrixes. In this study, the futuristic advantages of the lignin biopolymer were explored for the preparation of zero-valent Au NPs in the absence of any other reducing agents. The resulting lignin functionalized Au NPs (L-Auf NPs) were characterized via high-resolution transmission electron microscopy, X-ray diffraction, UV–vis spectroscopy, and Fourier-transform infrared spectroscopy. The optimum lignin concentration can generate uniformly dispersed crystalline L-Auf NPs. The optimized L-Auf (1–5) NPs permit the selective colorimetric detection of heavy metal ions; thus, the L-Auf (1–5) NPs demonstrated a highly selective colorimetric sensing tendency toward Pb2+ ions within a short time interval among the various metal ions (Pb2+, Fe3+, Cu2+, Cr6+, Co2+, Ag2+, Ca2+, Cd2+, Ba2+, and Hg2+). The prominent color change of L-Auf NPs from red wine to purple indicates the detection of Pb2+ ions. This robust characteristic nature of L-Auf (1–5) NPs can also detect very low concentrations of 1.8 μM in the linear range of 0.1–1 mM. Hence, the outcome of this study coincides with existing studies and indicates that L-Auf (1–5) NPs can also be used as effective sensors for the rapid and selective detection of Pb2+ ions via the colorimetric analysis using the real environmental samples.

Determination of nitric oxide using light-emitting diode-based colorimeter with tubular porous polypropylene membrane cuvette.

On the basis of the Griess-Saltzman (GS) reaction, an optical device for nitric oxide (NO) detection in exhaled breath and atmosphere was developed by employing the light-emitting diode (LED, 560nm) as the light source, light-to-voltage converter (LVC) as the detector, and porous polypropylene membrane tube (PPMT) as the cuvette. The PPMT was filled with GS reagents and covered with a coaxial jacket tube for gas collection and color reaction; two ends of the PPMT were connected with the LED and LVC to detect the change of light transmissivity in the wavelength range of 530 to 590nm mainly. A gas absorber filled with GS reagents was installed prior toanother absorber filled with KMnO4 solution to eliminate the interference of coexisting NO2. Under the optimized experimental conditions, the device achieved a limit of detection (3σ/k) of 4.4ppbv for NO detection. The linearity range of this device was divided into two segments, i.e., 25 to 100ppbv and 50 to 1000ppbv, with both coefficients of determination > 0.99. The relative standard deviation was 2.7% (n = 9, c = 100 ppbv), and the analytical time was 5.5min per detection. The minimum detectable quantity was decreased to 1.18ng, which was ~ 100 times lower than the original GS method (115ng). The present device was applied for determination of NO in exhaled breath, vehicle exhaust, and air. In addition to satisfactory spiking recoveries (i.e., 103% and 107%), the analytical results of the present device were in agreement with the results obtained by the standard method. These results assured the practicality of the developed device for NO detection in real environmental samples.

Genotoxic activity of endocrine disrupting compounds commonly present in paper mill effluents

In the present study we evaluated cytotoxic and genotoxic activities of endocrine disrupting compounds (EDCs), including dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP), bisphenol A (BPA), and nonylphenol (NP), which have been previously identified in effluents from two paper mills with different paper production technologies (virgin or recycled fibres). Moreover, we evaluated genotoxic activity of the effluents from these two paper mills and compared it to the activity of artificial complex mixtures consisting of the seven EDCs at concentrations detected in corresponding paper mill effluents. None of the EDCs was genotoxic in Salmonella typhimurium (SOS/umuC assay), while all induced DNA damage in human hepatocellular carcinoma (HepG2) cells (comet assay). After 4 h of exposure genotoxic effects were determined at concentrations ≥ 1 μg/L for BBP and DEHP, ≥10 μg/L for DMP, DEP, DBP, and BPA, and ≥100 μg/L for NP, while after 24 h of exposure DNA damage occurred at ≥10 μg/L for DBP, BPA and NP, and ≥100 μg/L for DMP, DEP, BBP and DEHP. The effluents and corresponding artificial mixtures of EDCs from paper mill that uses virgin fibres did not induce DNA damage in HepG2 cells, while the effluents and corresponding artificial mixtures for the paper mill that uses recycled fibres were genotoxic. Genotoxic activity of effluents was significantly higher compared to corresponding artificial mixtures suggesting the presence of further unknown compounds contributing to the effect. Wastewater monitoring based on chemical analysis is limited to determination of targeted compounds and does not take into account possible interactions between chemicals in mixtures. Therefore, it alone cannot provide an adequate information on potential toxic effects required for the assessment of genotoxic activity of real environmental samples and their potential threats to the environment and human health.

Nitrogen-Doped Graphdiyne as a Robust Electrochemical Biosensing Platform for Ultrasensitive Detection of Environmental Pollutants.

Owing to its unique chemical structure, natural pores, high structure defects, good surface hydrophilicity and biocompatibility, and favorable electrical conductivity, nitrogen-doped graphdiyne (NGDY) has been attracting attention in the application of electrochemical sensing. Taking advantage of these fascinating electrochemical properties, for the first time, two types of electrochemical enzymatic biosensors were fabricated for the respective detection of organophosphorus pesticides (OPs) and phenols based on the immobilization of acetylcholinesterase or tyrosinase with NGDY. Results revealed that the sensitivities of the NGDY-based enzymatic biosensors were almost twice higher than that of the matching biosensor in the absence of NGDY, proving that NGDY plays a vital role in immobilizing the enzymes and improving the performance of the fabricated biosensors. The effects of nitrogen doping on improving the biosensing performance were studied in depth. Graphitic N atoms can enhance the electrical conductivity, while imine N and pyridinic N can help to adsorb and accumulate the substance molecules to the electrode surface, all of which contribute to the significantly improved performance. Furthermore, these two types of biosensors also demonstrated excellent reproducibility, high stability, and good recovery rate in real environmental samples, which showed a valuable way for the rapid detection of OPs and phenols in the environment. With these excellent performances, it is strongly anticipated that NGDY has tremendous potential to be applied to many other biomedical and environmental fields.

An Untargeted Thermogravimetric Analysis-Fourier Transform Infrared-Gas Chromatography-Mass Spectrometry Approach for Plastic Polymer Identification.

Reliable chemical identification of specific polymers in environmental samples represents a major challenge in plastic research, especially with the wide range of commercial polymers available, along with variable additive mixtures. Thermogravimetric analysis-Fourier transform infrared-gas chromatography-mass spectrometry (TGA-FTIR-GC-MS) offers a unique characterization platform that provides both physical and chemical properties of the analyzed polymers. This study presents a library of 11 polymers generated using virgin plastics and post-consumer products. TGA inflection points and mass of remaining residues following pyrolysis, in some cases, proved to be indicative of the polymer type. FTIR analysis of the evolved gas was able to differentiate between all but polypropylene (PP) and polyethylene (PE). Finally, GC-MS was able to differentiate between the unique chemical fingerprints of all but one polymer in the library. This library was then used to characterize real environmental samples of mesoplastics collected from beaches in the U.K. and South Africa. Unambiguous identification of the polymer types was achieved, with PE being the most frequently detected polymer and with South African samples indicating variations that potentially resulted from aging and weathering.

Assessment of Melamine in Different Water Samples with ZnO-doped Co3 O4 Nanoparticles on a Glassy Carbon Electrode by Differential Pulse Voltammetry.

In this investigation, a melamine electrochemical sensor has been developed by using wet-chemically synthesized low-dimensional aggregated nanoparticles (NPs) of ZnO-doped Co3 O4 as sensing substrate that were decorated onto flat glassy carbon electrode (GCE). The characterization of NPs such as UV-Vis, FTIR, XRD, XPS, EDS, and FESEM was done for detailed investigations in optical, functional, structural, elemental, and morphological analyses. The ZnO-doped Co3 O4 NPs decorated GCE was used as a sensing probe to analyze the target chemical melamine in a phosphate buffer at pH 5.7 by applying differential pulse voltammetry (DPV). It exhibited good performances in terms of sensor analytical parameters such as large linear dynamic range (LDR; 0.15-1.35 mM) of melamine detection, high sensitivity (80.6 μA mM-1 cm-2 ), low limit of detection (LOD; 0.118±0.005 mM), low limit of quantification (LOQ; 0.393 mM), and fast response time (30 s). Besides this, the good reproducibility (in several hours) and repeatability were investigated under identical conditions. Moreover, it was implemented to measure the long-time stability, electron mobility, less charge-transfer resistance, and analyzed diffusion-controlled process for the oxidation reaction of the NPs assembled working GCE electrode, which showed outstanding chemical sensor performances. For validation, real environmental samples were collected from various water sources and investigated successfully with regard to the reliability of the selective melamine detection with prepared NPs coated sensor probe. Therefore, this approach might be introduced as an alternative route in the sensor technology to detect selectively unsafe chemicals by an electrochemical method with nanostructure-doped materials for the safety of environmental, ecological, healthcare fields in a broad scale.

Utility of a novel optical sensor design for ultra-trace detection of chromium colorimetrically in real environmental samples

ABSTRACT A novel optical sensor is investigated for sensitive and selective colorimetric determination of chromium(III) depended on the immobilisation of 2-(2`-hydroxynaph-thylazo)benzothiazole (HNABT) on a triacetylcellulose (TAC) membrane. Cr(III) ions react with the immobilised reagent to cause an increase in the absorption of the optode at 578 nm in thiel buffer solution of pH 6.5. Total chromium was detected by reduction of Cr(VI) to Cr(III) with concentrated sulphuric acid and ethanol. The amount of Cr(VI) was evaluated by the concentration difference between the total Cr and Cr(III). The influences of reagent concentration, pH and response time on the immobilisation of HNABT were investigated. The optode exhibits a linear range of 3.0 × 10−9 to 5.0 × 10−5 mol L−1 of Cr(III) ion with detection and quantification limits of 8.5 × 10−10 and 2.9 × 10−9 mol L−1, respectively. The newly designed optode has a response time of about 3.0 min. The influence of various possible interfering species was established and it was represented that the optode has very excellent selectivity. From the obtained results, the proposed optode benefits from advantages such as high stability, low cost, relatively long lifetime, fast response time, reproducibility, low detection and quantification limits. An excellent selectivity for Cr(III) ion detection among a large number of cations and anions was emphasised. The performance properties of the proposed procedure are compared with those of some techniques previously reported. The optode can be regenerated readily with 0.025 mol L−1 HNO3 and its response is reproducible and reversible [RSD < 1.7]. The proposed optode was successfully used for the detection of Cr(III) in various biological and environmental samples.

Simultaneous preconcentration and determination of zirconium in environmental samples using ultrasound-assisted ionic liquid based dispersive liquid-liquid microextraction combined with spectrophotometry

ABSTRACT The Green, delicate and rapid ultrasound-assisted ionic liquid-based dispersive liquid-liquid microextraction technique was developed to preconcentrate trace quantities of zirconium Zr(IV) ion in real samples prior to spectrophotometric detection. The proposed method uses (1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate) ionic liquid (IL) as an extraction solvent for Zr(IV) ions after the complexation with quinalizarin at pH 5.0. The effect of various analytical parameters has been investigated. The calibration graph was linear in the range of 2.0–400 µg L − 1 and the limit of detection was 0.6 µg L-1. The preconcentration factor was 100. Relative standard deviation (RSD%) at 200 µg L-1 of Zr(IV)for intra-day and inter-day precisionwere 2.0 and 2.7%, respectively (n = 10). Certified reference materialswere used to verify the accuracy.The proposed method was applied to preconcentrate and determine the content of Zr(IV) in real environmental (water, soil and plants) samples with satisfactory results.

Rapid analytical method for the determination of 220 pesticide with their isomers by GCMS-TIC.

This paper presents a cost-effective and validated multi residue modified and miniaturized method for the determination of 220 chemically different groups of pesticides and their isomers. This determination method is performed with single Quaid Gas Chromatography Mass Spectrometry -Total Ion Chromatogram GCMS-TIC. Two methods was experimented and modified with different GCMS parameters to analyses most common used pesticide and their residues in the standers solution and can be applied for real environmental samples. The results showed by single Quaid GCMS-TIC it can analyze 220 pesticides including their isomers within 49.6 min and low detection limit by using modified method 2 as described in this research. Limit of detection (LOD) was ranged from 0.78 to 14.74 ng/ml (ppb) with good separation and resolution. Limit of quantification (LOQ) was ranged between 2.34 and 44.22 ng/ml (ppb). Method 2 was more accurate, shorter, and clear separation rather than method 1. This method can be successfully applied in real environmental samples proven to be a good option for routine analysis of pesticide within the maximum residue limits (MRL) referenced to European commission especially with the most common GCMS-TIC which exists in most of labs and low income countries.

Electrochemical Detection of 2-Nitrophenol Using a Glassy Carbon Electrode Modified with BaO Nanorods.

Here, an electrochemical detection approach (differential pulse voltammetry) was employed to develop a 2-nitrophenol (2-NP) sensor probe using a glassy carbon electrode (GCE) coated by wet-chemically synthesized nanorods (NRs) of BaO. The prepared BaO NRs were characterized by field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (XRD) analysis. The peak currents by differential pulse voltammetric (DPV) analysis of 2-NP are plotted against the concentration to obtain the calibration curve of the 2-NP detection. It was found to be linear from 1.5 to 9.0 μM, defined as the dynamic range (LDR) for 2-NP detection in phosphate buffer solution. The sensor sensitivity was calculated from the slope of LDR by considering the active surface area of NRs coated on GCE (0.0316 cm2 ) and found as 17.6 μAμM-1 cm-2 . The limit of detection (LOD) was calculated as 0.50±0.025 μM from the signal/noise (S/N) ratio of 3. Moreover, the sensor analytical parameters such as reproducibility, long-term performing ability (stability), response time and validity in real environmental samples were found acceptable and to give satisfactory results. The development of a nanomaterial-based electrochemical chemical sensor might be an effective approach to sensor technology to detect carcinogenic and hazardous toxins for environmental safety and healthcare fields in a broad scale.