Analysis Of Environmental Samples Research Articles

Modular probe integrating with quantum dots based versatile platform for sensitive and label-free biomarker detection

Multiplexed analysis of biomarkers in a single sample tube is essential for accurate diagnosis and therapy of diseases. However, the existing detection platforms suffer from many drawbacks, such as low specificity, limited applicable sceneries, and complicated operation. Hence, it is highly important to develop a versatile biomarker detection platform that can be used for disease diagnosis and pathophysiological research. In this study, we provide a versatile method for detecting biomarkers using dual-loop probes and quantum dots (QDs). This approach utilizes a dual-loop probe that consists of a recognition module for identifying specific targets, a template recognition module for initiating subsequent chain replacement cycles, and a signal module for facilitating the fixation of QDs on the 96-well plate. The lower limit of detection for miRNA-21 is determined to be at the aM level. Furthermore, this design may be easily expanded to simultaneously detect several targets, such as miRNA and C-reactive protein. The experimental results demonstrated the successful construction of the versatile biomarkers detection platform, and indicated that the sensitive and versatile platform has significant potential in the areas of bio-sensing, clinical diagnostics, and environmental sample analysis.

Bacterial cellulose-supported dual-layered nanofibrous adsorbent for thin-film micro-solid-phase extraction of antibiotics in municipal wastewaters

In this study, bacterial cellulose was coated with composite nanofibers of polyvinyl alcohol doped with beta cyclodextrin and alginate (PVA-SA-βCD), constructed using the electrospinning technique. This novel material served as an effective adsorbent for thin-film micro-solid-phase extraction (TF-μSPE) of antibiotics from water samples, followed by HPLC-UV analysis. The adsorbent was subjected to a comprehensive characterization using ATR-FTIR, FE-SEM, and BET techniques. These analyses provided valuable insights into its physicochemical structure and properties. Several key parameters that affect the performance of the TF-μSPE method were investigated including electrospinning factors (voltage, flow rate, needle tip-collector distance, and electrospinning time), desorption solvent type and volume, adsorbent dose, adsorption and desorption times, pH value, and salt percentage. Under the optimized conditions, the limits of detections and quantifications for target antibiotics were obtained in the ranges of 0.02–0.03 and 0.07–0.1 μg L⁻1, respectively. The linear range was 0.07–1000 μg L⁻1 with satisfactory determination coefficients (r2) of 0.9944–0.9984. The intra-day and inter-day precisions were obtained as 1.1–1.7 % and 2.2–3.5 %, respectively. The developed method was successfully applied to determine antibiotics in municipal wastewater samples, yielding recoveries within the range of 70–100 % (RSD%<3.7). The green features of the method were also assessed based on AGREE tool. This is the first report on the fabrication of a double-layered nanofibrous adsorbent and its application for the adsorption of antibiotics in wastewater. This robust approach combines efficiency with analytical accuracy, making it a valuable tool for antibiotic analysis in environmental samples.

Pre-analytical challenges from adsorptive losses associated with thiamine analysis

Thiamine (vitamin B1) is an essential vitamin serving in its diphosphate form as a cofactor for enzymes in the citric acid cycle and pentose-phosphate pathways. Its concentration reported in the pM and nM range in environmental and clinical analyses prompted our consideration of the components used in pre-analytical processing, including the selection of filters, filter apparatuses, and sample vials. The seemingly innocuous use of glass fiber filters, glass filter flasks, and glass vials, ubiquitous in laboratory analysis of clinical and environmental samples, led to marked thiamine losses. 19.3 nM thiamine was recovered from a 100 nM standard following storage in glass autosampler vials and only 1 nM of thiamine was obtained in the filtrate of a 100 nM thiamine stock passed through a borosilicate glass fiber filter. We further observed a significant shift towards phosphorylated derivatives of thiamine when an equimolar mixture of thiamine, thiamine monophosphate, and thiamine diphosphate was stored in glass (most notably non-silanized glass, where a reduction of 54% of the thiamine peak area was observed) versus polypropylene autosampler vials. The selective losses of thiamine could lead to errors in interpreting the distribution of phosphorylated species in samples. Further, some loss of phosphorylated thiamine derivatives selectively to amber glass vials was observed relative to other glass vials. Our results suggest the use of polymeric filters (including nylon and cellulose acetate) and storage container materials (including polycarbonate and polypropylene) for thiamine handling. Losses to cellulose nitrate and polyethersulfone filters were far less substantial than to glass fiber filters, but were still notable given the low concentrations expected in samples. Thiamine losses were negated when thiamine was stored diluted in trichloroacetic acid or as thiochrome formed in situ, both of which are common practices, but not ubiquitous, in thiamine sample preparation.

Simple distance-based thread analytical device integrated with ion imprinted polymer for Zn2+ quantification in human urine samples.

This article presents the development of a distance-based thread analytical device (dTAD) integrated with an ion-imprinted polymer (IIP) for quantitative monitoring of zinc ions (Zn2+) in human urine samples. The IIP was easily chemically modified onto the thread channel using dithizone (DTZ) as a ligand to bind to Zn2+ with methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as well as 2,2-azobisisobutyronitrile (AIBN) as cross-linking agents to enhance the selectivity for Zn2+ detection. The imprinted polymer was characterized using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS). Under optimization, the linear detection range was from 1.0 to 20.0 mg L-1 (R2 = 0.9992) with a limit of detection (LOD) of 1.0 mg L-1. Other potentially interfering metal ions and molecules did not interfere with this approach, leading to high selectivity. Furthermore, our technique exhibits a remarkable recovery ranging from 100.48% to 103.16%, with the highest relative standard deviation (% RSD) of 5.44% for monitoring Zn2+ in human control urine samples, indicating high accuracy and precision. Similarly, there is no significant statistical difference between the results obtained using our method and standards on zinc supplement sample labels. The proposed method offers several advantages in detecting trace Zn2+ for point-of-care (POC) medical diagnostics and environmental sample analysis, such as ease of use, instrument-free readout, and cost efficiency. Overall, our developed dTAD-based IIP method holds potential for simple, affordable, and rapid detection of Zn2+ levels and can be applied to other metal ions' analysis.

Regression analysis for the determination of microplastics in sediments using differential scanning calorimetry.

This research addresses the growing need for fast and cost-efficient methods for microplastic (MP) analysis. We present a thermo-analytical method that enables the identification and quantification of different polymer types in sediment and sand composite samples based on their phase transition behavior. Differential scanning calorimetry (DSC) was performed, and the results were evaluated by using different regression models. The melting and crystallization enthalpies or the change in heat capacity at the glass transition point were measured as regression analysis data. Ten milligrams of sea sand was spiked with 0.05 to 1.5mg of microplastic particles (size: 100 to 200µm) of the semi-crystalline polymers LD-PE, HD-PE, PP, PA6, and PET, and the amorphous polymers PS and PVC. The results showed that a two-factorial regression enabled the unambiguous identification and robust quantification of different polymer types. The limits of quantification were 0.13 to 0.33mg and 0.40 to 1.84mg per measurement for semi-crystalline and amorphous polymers, respectively. Moreover, DSC is robust with regard to natural organic matrices and allows the fast and non-destructive analysis of microplastic within the analytical limits. Hence, DSC could expand the range of analytical methods for microplastics and compete with perturbation-prone chemical analyses such as thermal extraction-desorption gas chromatography-mass spectrometry or spectroscopic methods. Further work should focus on potential changes in phase transition behavior in more complex matrices and the application of DSC for MP analysis in environmental samples.

Total dissolved sulfide sensor based on biosynthesized silver nanoparticles and its applications in the environmental samples analysis

Total dissolved sulfide sensor based on biosynthesized silver nanoparticles and its applications in the environmental samples analysis

A facile, green synthesis of carbon quantum dots from folium cycas for rapid and sensitive determination of Fe3+ and cell imaging

In this study, biomass-derived carbon quantum dots (CQDs) were synthesized by an one-step hydrothermal method using folium cycas as a carbon source. By optimizing the reaction conditions, the fluorescence quantum yield of CQDs was obtained to be as high as 8.91%, and strong blue emission light was emitted. The characterization results showed that the CQDs were quasi-spherical with an average particle size of 2.69 ± 0.08 nm and contained a large number of hydrophilic functional groups with excellent water solubility and photostability. The CQDs showed high selectivity and sensitivity for the detection of Fe3+, with a low limit of detection of 0.72 μM and a wide linear range of 0–200 μM. The practical applicability of the CQDs was further established by carrying out Fe3+ detection in environmental sample analysis. Besides, CQDs have been successfully applied to in vitro cell imaging and bioimaging. The final by-product of the hydrothermal reaction, biochar, is used for dye adsorption. This work identifies the importance of using a relatively green process and an inexpensive biomass precursor to produce high-quality CQDs that hold a promising future for use in metal ion detection, bioimaging, and practical sensing applications.

A green flow-batch liquid phase microextraction lab-in-syringe platform based on natural deep eutectic solvents for toxic metal determination

In this work, a novel functional and reliable computer-controlled flow-batch lab-in-syringe (LIS) platform was developed for liquid phase microextraction (LPME) based on the use of natural deep eutectic solvents (NADES) as green alternatives to conventional extractants. The proposed automatic on-line LIS system is reported for the first time and demonstrated for the determination of toxic metals in aqueous samples, as a front-end to flame atomic absorption spectrometry (FAAS). To the best of our knowledge, the determination of metals by atomic spectrometric techniques processing a LIS preconcentration system using NADES has not been previously reported. The analytical process included the in-syringe metal complexation of Cd, Cu, and Pb (model analytes) with ammonium pyrrolidine dithiocarbamate and the subsequent microextraction of the resulted complexes by a mixture of menthol:heptanoic acid at a molar ratio of 1:2. After phase separation, the NADES was transferred towards the flame for direct atomization in an automatic and precise manner. The main attributes that affect the performance of the method were thoroughly studied. Under optimum conditions, the limits of detection ranged between 0.54 and 4.52 μg L−1 corresponding to a sample consumption of 4000 μL. The relative standard deviations were less than 3.8% demonstrating good method precision. As a proof-of-concept, the developed system was used for the analysis of drinking and environmental water samples resulting in good relative recoveries (i.e., 94.0–104.0%). The green character and the applicability of the proposed approach were demonstrated by the Green Analytical Procedure Index (GAPI), and Blue Applicability Grade Index (BAGI), respectively.

Influence of short lived radon and thoron progeny on the γ-spectroscopic analysis of low activity environmental and aerosol samples

In this work, the influence of radon and thoron progeny photons in γ-spectrometry analysis is thoroughly investigated. To this end three sampling and analysis campaigns were organized at the γ-spectrometry laboratory of Nuclear Engineering Laboratory of the National Technical University of Athens (NEL-NTUA), combining measurements of radon and its progeny via an ALPHAGUARD-ALPHAPM set up with background spectra of four germanium detectors as well as with outdoors meteorological conditions. Good statistical correlations were found between radon and its progeny with the respective photopeaks of the germanium detectors’ background as well as with meteorological conditions outdoors. Additionally, in all four detectors, six consecutive 2-day background spectra were compared with each other, with their mean and with the summed 12-day background spectrum, in order to study the photopeak background fluctuation and estimate the relevant uncertainties. This study supported the decision for the most suitable background spectrum to be used in γ-spectrometry analysis. Finally, in order to investigate the effect of both radon and thoron progeny on the MDA of typical radionuclides likely to be detected in aerosol samples, a series of air-sampling and γ-spectroscopic analysis scenarios were tested.

Rapid and selective detection of tetracyclic antibiotics in environmental water using Cu2+-doped hydrophilic imprinted melamine resin

Antibiotic contamination in environmental waters often occurs at low residue levels, necessitating pre-analysis concentration. To address this, we synthesized a hydrophilic molecularly imprinted resin (MIR) using melamine, urea, and formaldehyde as monomers, with oxytetracycline as the template molecule. Enhanced adsorption efficiency was achieved by doping the resin with Cu2+, which forms stable complexes with oxytetracycline. This Cu2+-doped MIR (Cu-MIR) was employed as a selective adsorbent in solid-phase extraction (SPE) to enrich four tetracycline antibiotics (TCs) from aqueous solutions. The optimized parameters for Cu-MIR in environmental water sample analysis resulted in linear detection ranges from 0.20 to 40 ng/mL, recoveries between 80.2 % to 102.4 %, relative standard deviations ≤ 9.0 %, a detection limit of 0.1 ng/mL, and the enrichment factors were between 4.79–5.13, as determined by HPLC-MS. Given its diverse adsorption mechanisms and specificity, Cu-MIR shows promise for practical applications in real-world sample analysis.

Electroextraction of methylene blue from aqueous environmental samples using paper points coupled with hollow fiber membranes

This article introduces a novel approach by coupling paper points with hollow fiber membrane for electroextraction (PP–HF-EE). The method was innovatively applied to extract methylene blue (MB) from large water volumes (up to 580 mL). A comprehensive study of six key parameters – organic filter, acceptor and donor phase composition, extraction time, applied voltage, and sample volume – was conducted using conventional flatbed scanning and digital image analysis. Our results revealed that extraction performance was primarily influenced by time, with low voltages (50 V) and low-conductivity organic filters (1-decanol) yielding comparable results to higher settings (300 V or 1-pentanol). Under optimized conditions (50 V, 60 min, 1-decanol as the organic filter), analytical performance parameters were assessed, demonstrating acceptable precision (RSD <18% for intra- and inter-day measurements) within a linear range of 5–100 μg L−1 (r = 0.98). PP–HF–EE demonstrated reliability through stable and reproducible electric current measurements during all extraction studies. Utilizing an extremely cost-effective detection system, PP–HF–EE achieved detection limits in the low ppb range, highlighting its potential as a promising variation of electromembrane extraction for environmental sample analysis.

Compound Similarity Network as a Novel Data Mining Strategy for High-Throughput Investigation of Degradation Pathways of Organic Pollutants in Industrial Wastewater Treatment.

Identification of degradation products and pathways is crucial for investigating emerging pollutants and evaluation of wastewater treatment methods. Nontargeted analysis is a powerful tool to comprehensively investigate the degradation pathways of organic pollutants in real-world wastewater samples but often generates large data sets, making it difficult to effectively locate the exact information on interests. Herein, to efficiently establish the linkages among compounds in the same degradation pathways, we introduce a compound similarity network (CSN) as a novel data mining strategy for LC-MS-based nontargeted analysis of complex wastewater samples. Different from molecular networks that cluster compounds based on MS/MS spectra similarity, our CSN strategy harnesses molecular fingerprints to establish linkages among compounds and thus is spectra-independent. The effectiveness of CSN was demonstrated by nontargeted identification of degradation pathways and products of organic pollutants in leather industrial wastewater that underwent laboratory-scale activated carbon adsorption (ACD) and ozonation treatments. Utilizing CSN in interpreting nontargeted data, we tentatively annotated 4324 compounds in the untreated leather industrial wastewater, 3246 after ACD, and 3777 after ACD/ozonation. We located 145 potential degradation pathways of organic pollutants in the ACD/ozonation process using CSN and validated 7 pathways with 15 chemical standards. CSN also revealed 5 clusters of emerging pollutants, from which 3 compounds were selected for in vitro cytotoxicity study to evaluate their potential biohazards as new pollutants. As CSN offers an efficient way to connect massive compounds and to find multiple degradation pathways in a high-throughput manner, we anticipate that it will find wide applications in nontargeted analysis of diverse environmental samples.

Culture-independent detection of low-abundant Clostridioides difficile in environmental DNA via PCR.

Clostridioides difficile represents a major burden to public health. As a well-known nosocomial pathogen whose occurrence is highly associated with antibiotic treatment, most examined C. difficile strains originated from clinical specimen and were isolated under selective conditions employing antibiotics. This suggests a significant bias among analyzed C. difficile strains, which impedes a holistic view on this pathogen. In order to support extensive isolation of C. difficile strains from environmental samples, we designed a detection PCR that targets the hpdBCA-operon and thereby identifies low abundances of C. difficile in environmental samples. This operon encodes the 4-hydroxyphenylacetate decarboxylase, which catalyzes the production of the antimicrobial compound para-cresol. Amplicon-based analyses of diverse environmental samples demonstrated that the designed PCR is highly specific for C. difficile and successfully detected C. difficile despite its absence in general 16S rRNA gene-based detection strategies. Further analyses revealed the potential of the hpdBCA detection PCR sequence for initial phylogenetic classification, which allows assessment of C. difficile diversity in environmental samples via amplicon sequencing. Our findings furthermore showed that C. difficile strains isolated under antibiotic treatment from environmental samples were originally dominated by other strains according to PCR amplicon results. This provided evidence for selective cultivation of under-represented but antibiotic-resistant isolates. Thereby, we revealed a substantial bias in C. difficile isolation and research.IMPORTANCEClostridioides difficile is a main cause of diarrheic infections after antibiotic treatment with serious morbidity and mortality worldwide. Research on this pathogen and its virulence has focused on bacterial isolation from clinical specimens under antibiotic treatment, which implies a substantial bias in isolated strains. Comprehensive studies, however, require an unbiased strain collection, which is accomplished by isolation of C. difficile from diverse environmental samples and avoidance of antibiotic-based enrichment strategies. Thus, isolation can significantly benefit from our C. difficile-specific detection PCR, which rapidly verifies C. difficile presence in environmental samples and further allows estimation of the C. difficile diversity by using next-generation sequencing.

On-Off-On Fluorometric Detection of Hg(II) and L-Cysteine Using Red Emissive Nitrogen-Doped Carbon Dots for Environmental and Clinical Sample Analysis.

This research introduces a novel fluorescence sensor 'on-off-on' employing nitrogen-doped carbon dots (N-CDs) with an 'on-off-on' mechanism for the selective and sensitive detection of Hg(II) and L-cysteine (L-Cys). N-CDs was synthesized using citric acid as the carbon precursor and urea as the nitrogen source in dimethylformamide (DMF) solvent, resulting in red emissive characteristics under UV light. Comprehensive spectroscopic analyses, including UV-Vis, fluorescence, FT-IR, XRD, XPS, Raman, and Zeta potential techniques, validated the structural and optical characteristics of the synthesized N-CDs. The maximum excitation and emission of N-CDs were observed at 548 and 622nm, respectively. The quantum yield of N-CDs was calculated to be 16.1%. The fluorescence of N-CDs effectively quenches upon the addition of Hg(II) due to the strong coordination between Hg(II) and the surface functionalities of N-CDs. Conversely, upon the subsequent addition of L-Cys, the fluorescence of N-CDs was restored. This restoration can be attributed to the stronger affinity of the -SH group in L-Cys towards Hg(II) relative to the surface functionalities of N-CDs. This dual-mode response enabled the detection of Hg(II) and L-Cys with impressive detection limits of 15.1 nM and 8.0 nM, respectively. This sensor methodology effectively detects Hg(II) in lake water samples and L-Cys levels in human urine, with a recovery range between 99 and 101%. Furthermore, the N-CDs demonstrated excellent stability, high sensitivity, and selectivity, making them a promising fluorescence on-off-on probe for both environmental monitoring of Hg(II) and clinical diagnostics of L-Cys.

An Ultra-low Detection Limit Fe3+ Optical Fiber Fluorescent Sensor Based on a Anti-B18H22 Derivative withAggregation-inducedEmission Enhancement.

A fluorescent Fe3+ probe ((C10H7NO2)2B18H20, M1) by introducing two isoquinoline-1-carboxylic acid group into the 6,9-position of anti-B18H22 was designed and synthesized. The structure of M1 was investigated by 1H NMR, MS, FT-IR and theoretical calculation, and its optical properties were characterized with UV-Vis and PL. M1 showed aggregation induced emission enhancement (AIEE) properties in THF/H2O solution, and exhibited an excellent selectivity toward Fe3+ in THF/H2O (v/v, ƒw = 95%) solution with a detection limit of 1.93 × 10-5M. The interaction mechanism of probe for detecting Fe3+ is attributed to the involvement of intramolecular charge transfer (ICT) process. Furthermore, a optical fiber fluorescent Fe3+ sensor based on M1 sensing film was developed, the detection limit of the optical fiber Fe3+ fluorescent sensor could be improved to13.8pM, the ultra-low detection limit is superior to most reported fluorescent probes (or sensors) towards Fe3+. This method has the advantages of high sensitivity, anti-interference and easy to operate, and has great potential in the field of the analysis of environmental and biological samples.

An overview of automated flow systems for total and isotopic analysis of strontium and yttrium in samples of environmental interest

Due to the different uses of radioactivity during the last decades, there has been an increase in the concentration of natural and artificial radionuclides in the environment. This, along with some accidents with a high affect public opinion (for example, Chernobyl and Fukushima), have led to the growth and establishment of environmental radioactivity monitoring programs. Currently, trends in legislation and research are focused on the development of accurate, precise, reliable and fast analytical methods with low limits of detection (LOD) for radionuclides determination, such as strontium and yttrium, in environmental samples. In this paper, two comprehensive reviews and four automated analytical systems for total and isotopic determination of yttrium and strontium are presented. The developed methods have been applied in the analysis of environmental samples with low concentrations of these analytes. These methodologies have been automated by exploiting flow analysis techniques, such as multi-syringe flow injection analysis (MSFIA), Sequential injection analysis (SIA) and laboratory-on-valve (LOV) systems, achieving a minimal handling and low consumption of samples and reagents, a significant reduction in waste generation and a high frequency of analysis. In the developed methodologies, some spectrometric methods such as ICP-OES and ICP-MS have been implemented as detection techniques instead of radiometric detectors obtaining a fully automated, low-cost and fast yttrium and strontium determinations.

Understanding Synthesis Parameters for Thionation of Phosphonates Associated with the Chemical Weapons Convention through Principal Component Analysis

Thiophosphonates, a class of the organophosphate compounds, are of pharmaceutical and agricultural significance. Albeit their broad scope for peaceful uses, they may also be precursors and markers to toxic chemicals, such as the nerve agent VX and other V-series agents, leading to their inclusion into the Annex on Chemicals of the Chemical Weapons Convention (CWC). Considering that they are related to chemical warfare agents and the position of our laboratory as an Organization for the Prohibition of Chemical Weapons (OPCW) Designated Laboratory for analysis of authentic environmental samples, this study aims to contribute to the understanding of the synthesis of thiophosphonates through O,O’-diethyl methylphosphonate conversion to O,O’-diethyl methylphosphonothioate using Lawesson’s reagent, exploring different conditions previously reported by the literature, in order to further build a compound library for CWC verification purposes. Synthesis of the compounds has been carried out in sealed, pressure tubes, adding novelty to the present study. Reactions were followed by gas chromatography and 31P nuclear magnetic resonance, and principal component analysis was employed to understand the intricate factors influencing thiophosphonate synthesis yield as duration, temperature and solvent. The research aims to reinforce or challenge existing scientific knowledge, providing insights into parameters related to phosphonate thionation using Lawesson’s reagent, contributing to a deeper understanding of this chemical reaction.

Facile synthesis of sulphur-doped carbon dots (S-CDs) using a hydrothermal method for the selective sensing of Cr6+ and Fe3+ ions: application to environmental water sample analysis.

In this work, we used a one-step hydrothermal method to synthesize blue-emission sulfur-doped carbon dots (S-CDs) using jaggery as a carbon precursor. The synthesized carbon quantum dots showed low toxicity, good water solubility, anti-interference properties, and stable fluorescence. When excited at 310 nm, the S-CDs produced bright emission with a quantum yield of 7.15% at 397 nm. The S-CDs exhibited selective and sensitive quenching responses with limits of detection (LODs) of 4.25 μg mL-1 and 3.15 μg mL-1 for variable concentrations of Cr6+ and Fe3+, respectively, accompanied by a consistent linear relationship between fluorescence intensity and these concentrations. Fluorescence lifetime measurements were used to investigate the fluorescence quenching mechanism, which supports the static type of quenching. Outstanding benefits of the developed S-CD based fluorescence probe include its low cost, excellent sensitivity and selectivity, and ease of use for the detection of Cr6+ and Fe3+ ions. The developed carbon dot based fluorescent probe was successfully used to detect Cr6+ and Fe3+ ions in real water samples with an excellent recovery ratio.

A novel in situ method for linear alkylbenzene sulfonate quantification in environmental samples using a digital image-based method.

Surfactants from detergents, when inadequately treated in sewage treatment plants, are carried away into estuaries, resulting in the contamination of aquatic environments. It is thus necessary to develop rapid and efficient techniques that are capable of effectively monitoring these pollutants. In this context, for the first time in the literature, this study reports the development and application of a digital image-based (DIB) method for the in situ quantification of the anionic surfactant linear alkylbenzene sulfonate (LAS) in water bodies using a smartphone. The DIB method is a highly effective modern detection method based on methylene blue, which is employed as a modified alternative technique to the spectrophotometric method and commonly used in environmental studies; in the DIB method, the images of interest are obtained using a smartphone and the analyses are carried out using free software Color grab. The results obtained from the application of the DIB method showed that the method possesses high precision and accuracy, with a linear calibration curve in the range of 0.15 to 4.5 mg L-1, R2 = 0.993, a limit of detection of 6.0 μg L-1, and recovery rates ranging from 82.7% to 114%. The efficacy of the proposed method was evaluated by comparing its results with those of spectrophotometry (used as a reference method) through the analysis of environmental samples obtained from the Capibaribe River Estuary using methylene blue. No statistically significant differences were observed between the results obtained from the DIB and the spectrophotometric method. The innovative method proposed in this study is fast, economical and environmentally friendly; the technique involves the use of only a few microliters of samples and generates little waste compared to spectrophotometry. In addition, the proposed method is applicable for in situ analyses, allowing real-time monitoring of LAS in different types of aquatic environments.

Sulfolane Analysis in Environmental Samples: A Critical Review

Sulfolane, a highly water-soluble industrial solvent, has raised environmental concerns due to its widespread usage and its prolonged persistence once released into the environment. To assess the extent of contamination effectively, reliable analytical methods are essential. In this review article, the existing methodologies for the sample preparation and determination of sulfolane are systematically examined and evaluated. In brief, existing guidelines for sampling from environmental matrices provide a solid foundation for sulfolane analysis. Notably, there is little variation in the choice of final determination methods, with GC-MS or GC-FID being favored across all studies. However, substantial variability emerges in sample preparation methods. Moreover, upon scrutiny of the analytical procedures utilized in sulfolane analysis, it becomes evident that a considerable number of them are characterized by inefficiency or environmental hazards, often relying on substantial quantities of chlorinated solvents. Through this review, valuable insights into the challenges at hand and potential solutions can be gained, offering a foundation for the development of novel sulfolane analysis methods applicable to a range of environmental matrices. Overall, this field calls for further research to devise efficient and environmentally sustainable analytical methods for sulfolane analysis.