Pure Water Samples Research Articles

Dark-field hyperspectral microscopy for label-free microplastics and nanoplastics detection and identification invivo: A Caenorhabditis elegans study.

Microplastics pollution is a serious ecological threat, severely affecting environments and human health. Tackling microplastics pollution requires an effective methodology to detect minute polymer particles in environmental samples and organisms. Here were report a novel methodology to visualise and identify nanoscale (down to 100nm) and microscale synthetic commercially-available uniform spherical polymer particles using dark-field hyperspectral microscopy in visible-near infrared (400-1000nm) wavelength range. Polystyrene particles with diameters between 100nm-1μm, polymethacrylate 1μm and melamine formaldehyde 2μm microspheres suspended in pure water samples were effectively imaged and chemically identified based on spectral signatures and image-assisted analysis. We succeeded in visualisation and spectral identification of pure and mixed nano- and microplastics invivo employing optically-transparent Caenorhabditis elegans nematodes as a model to demonstrate the ingestion and tissue distribution of microplastics. As we demonstrate here, dark-field hyperspectral microscopy is capable for differentiating between chemically-different microplastics confined within live invertebrate intestines. Moreover, this optical technology allows for quantitative identification of microplastics ingested by nematodes. We believe that this label-free non-destructive methodology will find numerous applications in environmental nano- and microplastics detection and quantification, investigation of their biodistribution in tissues and organs and nanotoxicology.

Evaluation of commercial virtually imaged phase array and Fabry-Pérot based Brillouin spectrometers for applications to biology.

Measuring the complex mechanical properties of biological objects has become a necessity to answer key questions in mechanobiology and to propose innovative clinical and therapeutic strategies. In this context, Brillouin light scattering (BLS) has recently come into vogue, offering quantitative imaging of the mechanical properties without labels and with a micrometer resolution. In biological samples, the magnitude of the spectral changes are typically of a few tens of MHz, and the ability of modern spectrometers to monitor such subtle changes needs to be evaluated. Moreover, the multiplicity of variations in optical arrangements, specific to each lab, requires to set a standard for the assessment of the characteristics of BLS systems. In this paper we propose a protocol to evaluate the precision and accuracy of two commercial spectrometers that is reproducible across labs. For a meaningful comparison, we coupled the spectrometers to the same microscope and to the same laser. We first evaluated the optimum acquisition time and laser power. We evaluated the precision using pure water samples. We determined the accuracy by probing water solutions with increasing concentration of salt and comparing it with theory. Following these quantifications, we applied the VIPA-based spectrometer to tumor spheroids engineered from different cell lines that possess different metastatic potentials and resistance to therapies. On these models, we detected significant changes in the linewidth suggesting that BLS measurements of the viscosity could be used as a read-out to distinguish different levels of drug resistance.

Phosphorus-Doped Carbon Quantum Dots as Fluorometric Probes for Iron Detection.

Carbon quantum dots (CQDs), a novel fluorescent nanomaterial, have been extensively employed/explored in various applications, that is, biosensors, bioimaging, nanomedicine, therapeutics, photocatalysis, electrocatalysis, energy storage system, and so forth. In this study, we report the synthesis, characterization, and the application of phosphorus-doped CQDs (PCQDs), synthesized using trisodium citrate and phosphoric acid by the hydrothermal method. The effect of phosphorus doping on optical features and the formation of PCQDs have been explored elaborately by controlling the concentrations of precursors, reaction time, and the temperature. The fluorescent quantum yield for PCQDs was determined to be 16.1% at an excitation/emission wavelength of 310/440 nm. Also, the optical and structural properties of PCQDs were determined by using various spectroscopic and microscopic techniques. Static quenching of fluorescence was determined upon the addition of Fe3+ to PCQDs because of the formation of the fluorescent inactive complex (PCQDs–Fe3+). Hence, this chemistry leads to the development of a new fluorometric assay for the detection of Fe3+. The lower limit of Fe3+ detection is determined to be 9.5 nM (3σ/slope), with the linear fit from 20 nM to 3.0 μM (R2 = 0.99). We have validated this new assay in the raw, ejected, and purified water samples of the RO plant by the standard addition method. These results suggest the possibility of developing a new commercial assay for Fe3+ detection in blood, urine, and various industrial waste and sewage water samples. Furthermore, recycling the pollutant water into the freshwater using filters that consist of PCQDs offers a great deal.

Deteksi Migrasi Material Pembungkus Makanan ke Air karena Pemanasan

This research was aimed to detect if migration of additives or other components from plastic material used as packaging of hot food/drinks were occurred in warm-hot cooked temperature. In this works, plastic samples as like spoon, packaging, and wraps were taken directly from mainly street food vendors and shops. Pure water and plastics samples were mixed, and heat were introduced to induced migration. Three temperature of 60 °C, 80 °C, dan 100 °C, were each applied to induced migration for one hour. Migrations were detected using UV-Visible Spectroscopy, Fourier Transform InfraRed, and Gas Chromatography. Migrated polymer materials from plastics were detected through peaks of UV-visible absorption with water as background spectra were subtracted, and its functional groups were detected using FTIR spectroscopy. Gas chromatography was used to confirm if UV-visible and FTIR results were result from single component migration.
 Keywords: polymer, migration, temperature, plastics, wavelength.

Preparation and characterization of novel MWCNTs/Fe-Co doped TNTs nanocomposite for potentiometric determination of sulpiride in real water samples

Novel multiwalled carbon nanotubes/ Fe-Co doped titanate nanotubes nanocomposite (MWCNTs/Fe-Co doped TNTs) facilitated the charge transfer and enhanced sensitivity and selectivity. Herein, three novel modified carbon paste sensors (CPSs) based on MWCNTs (sensor I), Fe-Co doped TNTs (sensor II) and MWCNTs/Fe-Co doped TNTs composite (sensor III) were fabricated for a simple, low cost and high accuracy electrochemical method for the potentiometric determination of sulpiride (SLP). The sensors exhibited excellent Nernstian slopes 57.1 ± 0.4, 56 ± 0.5 and 58.8 ± 0.2 mV decade−1 with detection limits (DL) 7.6 × 10−7, 1.58 × 10−6 and 8.7 × 10−8 mol L−1, quantification limits (QL) 2.5 × 10−6, 5.2 × 10−6 and 2.9 × 10−7 mol L−1 for a long lifetime 20, 18, and 25 weeks for sensors (I), (II), and (III), respectively. The modified sensor (III) was applicable by measuring the concentration of spiked SLP in pure solutions, pharmaceutical products, human urine, and real water samples. The proposed method can be used as an important analytical tool in the quality control of the pharmaceutical industry.

Effects of pulsed magnetic field on freezing kinetics and physical properties of water and cucumber tissue fluid

In this paper, a special experimental device was designed to study the effect of pulsed magnetic fields (PMF) on freezing kinetics and physical properties of water and cucumber tissue fluid. Pure water and cucumber tissue fluid samples with 3.5 mL were frozen in PMF generated by a pair of Helmholtz coils. The magnetic flux density ranged from 0 to 6 mT in the experiment. The results show that PMF treatment significantly reduced the freezing point temperature (Tice) of water and cucumber tissue fluid with 0.59 °C and 0.74 °C, respectively. Within a certain range of magnetic flux density, PMF treatment not only significantly reduced initial nucleation temperature and the temperature of end point of freezing, but also significantly reduced the phase transition time and the tempering time of both water and cucumber tissue fluid. However, the effects of PMF treatment on the total freezing time of water and cucumber tissue fluid were different. These may be related to the effects of Lorentz forces generated by PMF on the hydrogen bonds, water molecule clusters, ice crystals, charged particles and ferromagnetic particles in the fluid.

Hyperpolarized water through dissolution dynamic nuclear polarization with UV-generated radicals

In recent years, hyperpolarization of water protons via dissolution Dynamic Nuclear Polarization (dDNP) has attracted increasing interest in the magnetic resonance community. Hyperpolarized water may provide an alternative to Gd-based contrast agents for angiographic and perfusion Magnetic Resonance Imaging (MRI) examinations, and it may report on chemical and biochemical reactions and proton exchange while perfoming Nuclear Magnetic Resonance (NMR) investigations. However, hyperpolarizing water protons is challenging. The main reason is the presence of radicals, required to create the hyperpolarized nuclear spin state. Indeed, the radicals will also be the main source of relaxation during the dissolution and transfer to the NMR or MRI system. In this work, we report water magnetizations otherwise requiring a field of 10,000 T at room temperature on a sample of pure water, by employing dDNP via UV-generated, labile radicals. We demonstrate the potential of our methodology by acquiring a 15N spectrum from natural abundance urea with a single scan, after spontaneous magnetization transfer from water protons to nitrogen nuclei.

Heavy Metal Extraction under Environmentally Relevant Conditions Using 3-Hydroxy-2-Naphthoate- Based Ionic Liquids: Extraction Capabilities vs. Acute Algal Toxicity

We investigated the applicability of three task-specific ionic liquids (ILs) as heavy metal extracting agents by contrasting extraction capabilities with algal toxicity. The compounds tested were trihexyltetradecylphosphonium-, methyltrioctylphosphonium- and methyltrioctylammonium 3-hydroxy-2-naphthoates. Experiments were performed to assess if these ILs can provide environmentally safe residual concentrations of the target metals after extraction. Both pure water and natural mineral water samples were spiked with 20 µg L−1 of Cu, Ag, Cd, Hg and Pb, respectively. Quantitative extraction (> 99%) of Hg and Ag was achieved. Cu and Hg were below the respective no-observed-effect-concentrations (NOECs) after extraction and Ag below 0.03 µg L−1. Acute toxicity assays were conducted using two freshwater green algae Raphidocelis subcapitata and Tetradesmus obliquus. Growth inhibition and maximum photochemical quantum yield of photosystem II after 72 h were assessed. ILs were less toxic than similar compounds, but still must be classified as acute toxicants for algae. An inhibiting effect on both growth and chlorophyll fluorescence was observed. The leaching of the ILs into the samples remains a limitation regarding their environmental-friendly applicability. Nonetheless, the extremely efficient removal of Cu, Ag and Hg under environmentally relevant conditions calls for further research, which should focus on the immobilization of the ILs.

Purifications of petroleum products contaminated water using modified rice husk ash filters

This study evaluated the effects of different ceramic candle filters made from blends of rice husk ash (RHA), polyethylene glycol (PEG), and clay for effectiveness in purifying petroleum products contaminated water. The filters were characterized for porosity, swellability and water permeability. Performances of the candle filters were evaluated based on the physicochemical analysis of the untreated and purified water samples. The parameters measured include total dissolved solids (TDS), hardness, phosphates, nitrates, and chloride. Results from this investigation indicated that water diffusion in the filters, depends on filter dimensions-as permeability increased with decrease in filter’s surface area. This was also seen in the average flux obtained for the candles. The filter EL4 has a flux of 0.0070 ml/min.cm2, EL3 has 0.0199 ml/min.cm2. Also, the porosity of the filters increased with the amount of porogen used. An improvement in physical appearance of the water samples was seen after purification of the contaminated water. The chloride and TDS content of the untreated water samples were 260.1 ± 7.705 mg/L and 596.7 ± 30.32 mg/L respectively, while the chloride and TDS contents of filtrates obtained from filter made from RHA/Eleme clay and PEG as porogen (EL3) to 246.4 ± 1.915 mg/L and 511.7 ± 13.3 mg/L respectively. All the filters increased the phosphate and nitrate contents of filtrates compared to the untreated water samples. Total polycyclic hydrocarbon was reduced up to 85% by EL4 filter. The values of heavy metals found in the water samples were within the permissible limit for irrigation water. The low preparation cost, ease of preparation and purification results of these candle filters will boost their applications for water remediation in areas with high level of contamination particularly for irrigation and other household purposes but not drinking and cooking.

Efficiency of Nitrifying and Denitrifying Bacteria in Removing Micropollutants in Water Samples

Several regions of the world have been suffering from problems of water quality degradation caused mainly by the input of nutrients such as nitrogen and phosphorus, resulting from anthropic activities. In excess, these nutrients can be considered micropollutants that could be responsible for the blooms of aquatic plant species, algae, and potentially toxic cyanobacteria, resulting in the interference of water quality in the socio-economic and environmental sector. Biological mitigation measures using specific microorganisms have been applied for the removal of micro pollutants due to their high efficiency of nitrogen and phosphorus. The present study analyzed the efficiency of nitrifying bacteria such as N. europaea and N. winodradskyi and P. denitrificans denitrifying bacteria, individually and as a bacterial pool (formed by N. europaea, N. winodradskyi, and P. denitrificans), in removing NH3, NO2−, NO3−, N, P, and PO43−, in pure water samples at times 0 to 1440 min and 0 to 7200 min. N. europaea and N. winodradskyi presented 100% removal efficiency for compounds NH3 and NO2− respectively, and bacterial pool removed 100% of compounds NO2− and P at time 1440 min (24 h). At time 7200 min (120 h), P. denitrificans obtained 100% removal of NO2− and NO3−. Over time, the bacterial pool obtained 100% removal for all compounds analyzed in the present study. This paper demonstrated the excellent performance of microorganisms in the removal of nitrogen and phosphorus compounds in pure water samples.

Investigating aquaphotomics for temperature-independent prediction of soluble solids content of pure apple juice

The methods of aquaphotomics were explored as an aid to improve near infrared spectroscopic predictive modelling of the soluble solids content of pure apple juice at different temperatures. The study focussed on the first overtone region of the O–H stretching vibration of water (1300–1600 nm). A transmission-based FT-NIR (Fourier transform near infrared) spectrometer was used to acquire 103 spectra of freshly expressed juice samples from individual ‘Braeburn’ apples over the wavelength range of 870–1800 nm with a 1 mm cuvette at three temperatures, 20, 25 and 30°C. The aquagram of the first overtone water region showed a trend of increasing bound water absorption with rising soluble solids content, from 7.3 to 13.7°Brix, and increasing free water absorption with rising temperature from 20 to 30°C. Predictive models for apple juice soluble solids content at 25°C were developed using partial least squares regression with spectral pre-processing by standard normal variate (SNV) followed by second derivative transformation (SNV + 2D) or no pre-processing on absorbance spectra at all. The best result, with lowest standard error of prediction of 0.38°Brix, was obtained using the first overtone water region with partial least squares regression on the SNV + 2D spectra. The method of extended multiplicative scatter correction was used, as an additional pre-processing step, to improve apple juice soluble solids content prediction at different temperatures. The interference component selected for the extended multiplicative scatter correction method was the first principal component loading measured using pure water samples taken at the same three temperatures (20, 25 and 30°C). Such extended multiplicative scatter correction pre-processing greatly reduced the soluble solids content prediction bias, when applying the partial least squares regression model developed at 20°C to samples measured at 25 and 30°C, from 0.23 to 0.08 and 0.36 to 0.13°Brix, respectively. Model precision (in terms of standard error of prediction) was also slightly improved by 0.02°Brix in each case, from 0.40 to 0.38 and 0.46 to 0.44°Brix at 25 and 30°C respectively.

Integrated System for the Rapid Polycyclic Aromatic Hydrocarbons Extraction from Aqueous Samples and Their Consecutive Thermal Desorption Prior to Gas Chromatography Analysis

This paper describes for the first time the extraction followed by thermal desorption of polycyclic aromatic hydrocarbons (PAHs) spiked water samples in a microfluidic silicon device. Thanks to the integration into an original system composed of a micropump, microvalves, and an optimized thermal management, the entire protocol is automated and combines the extraction, the drying and the desorption in less than 25 min before sending the sample to a GC-FID system. Repeatable recovery yields have been determined for 1 μg/L spiked water samples and the analysis of PAHs in a natural water spiked sample has been demonstrated without loss of performance compared to purified water samples. Compared to other extraction techniques, this system has the advantage of reduced footprint, reduced energy consumption and no solvent use.

Conductometric sensor for viable Escherichia coli and Staphylococcus aureus based on magnetic analyte separation via aptamer.

A method is described to determine viablepopulations of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The method employs aptamer-magnetic separation combined with resistivity based detection. The bacteria were separated by means of aptamer-functionalized magnetic beads. They were then quantified by measuring their growth kinetics through time-dependent conductivity changes of culture media. The time-course of growth was logged by real-time and contactless measurements that yielded starting concentrations from the duration of lag intervals prior to the log phase of growth. In pure water samples, the linear ranges for measuring E. coli and S. aureus cells are 2.5 × 103-2.5 × 108CFU·mL-1 and 4.1 × 103-4.1 × 108CFU·mL-1, respectively. In spiked tap water samples, the lower limits of detection are 2.3 × 104CFU·mL-1 and 4.0 × 103CFU·mL-1 for E. coli and S. aureus, with recoveries of 87.0-108.7% and 92.5-105.0%, respectively. The relative standard deviation of these measurements (10.0%) is below that of plate counting method (13.9%). The presence of micro/nanoparticles such as magnetic beads or selenium nanoparticles in the culture media does not interfere, unlike in case ofautomatted optical density monitoring. The E. coli and S. aureus cells captured on the aptamer-functionalized magnetic beads can be directly tested for their susceptibility to antibiotics. The process of magnetic separation and determination of load burden requires neither bulky, sophisticated equipment nor expensive reagents. Graphical abstractAptamer-functionalized magnetic beads are used to selectively capture and separate E. coli and S. aureus cells in aqueous samples. They are directly transferred to a multichannel conductometric sensor for the quantification of viable bacteria via automated monitoring of their growth kinetics.

Purification of lake water using a PES hollow fiber membrane

Abstract Water scarcity combined with increasing populations will create a massive problem of obtaining clean water sources in the future. In this research, a newly developed polyethersulfone (PES) hollow fiber membrane from Universiti Sains Malaysia (USM) is used in water purification experiments using raw water samples obtained from Varsity Lake of the University of Malaya (UM) and a lake in Taman Jaya. The raw water samples undergo water quality characteristics tests to determine their class of water quality based on national water quality standards. Both raw water samples have been characterized and belong to class II of water quality. Subsequently, both raw water samples are used in water purification experiments with two types of filtration configuration, cross-flow and dead-end. Results show that water purification using the PES hollow fiber membrane can obtain water quality of class I for both samples. However, the presence of Escherichia coli can still be detected in both purified water samples. From the results obtained, the fabricated PES membrane is able to filter raw water samples of WQI Class II to WQI Class I quality and adhere to drinking water standards, and the dead-end filtration configuration provides the best filtration performance.

Effect of the frequency of weak oscillating magnetic fields on supercooling and freezing kinetics of pure water and 0.9% NaCl solutions

Several studies in the literature suggest that the frequency of weak oscillating magnetic fields (OMFs) significantly affects supercooling and freezing kinetics, although the effects described by different authors are apparently contradictory. To shed light on this matter, we froze pure water samples and 0.9% NaCl solutions in a 0.8-mT magnetic field at different frequencies (20, 50, 200, and 2000 Hz). Moreover, experiments with no OMF application were also performed to act as controls. Our results show that the application of a 0.8-mT OMF at frequencies between 20 Hz and 2000 Hz during freezing has no effect on the parameters that characterize either supercooling (time at which nucleation occurred and extent of supercooling achieved at the sample center) or freezing kinetics (precooling, phase transition, and tempering times), both in pure water and 0.9% NaCl solutions. More research is needed to elucidate all the factors that could affect OMF-assisted freezing.

Construction and characterization of nano iron complex ionophore for electrochemical determination of Fe(III) in pure and various real water samples

Electrochemical methods represent an important class of widely used techniques for the detection of metal ions. The unique chemical and physical properties of nanoparticles make them extremely suitable for designing new and improved sensing devices, especially electrochemical sensors and biosensors. This study focused on the synthesis of a nano‐Fe(III)–Sud complex and its characterization using various spectroscopic and analytical tools, optimized using the density functional theory method, screened for antibacterial activity and evaluated for possible binding to DNA using molecular docking study. Proceeding from the collected information, nano‐Fe(III)–Sud was used further for constructing carbon paste and screen‐printed ion‐selective electrodes. The proposed sensors were successfully applied for the determination of Fe(III) ions in various real and environmental water samples. Some texture analyses of the electrode surface were conducted using atomic force microscopy. At optimum values of various conditions, the proposed electrodes responded towards Fe(III) ions linearly in the range 2.5 × 10−9–1 × 10−2 and 1.0 × 10−8–1 × 10−2 M with slope of 19.73 ± 0.82 and 18.57 ± 0.32 mV decade−1 of Fe(III) ion concentration and detection limit of 2.5 × 10−9 and 1.0 × 10−8 M for Fe(III)–Sud‐SPE (electrode I) and Fe(III)–Sud‐CPE (electrode II), respectively. The electrode response is independent of pH in the range 2.0–7.0 and 2.5–7.0, with a fast response time (4 and 7 s) at 25°C for electrode I and electrode II, respectively. Moreover, the electrodes also showed high selectivity and long lifetime (more than 6 and 3 months for electrode I and electrode II, respectively). The electrodes showed good selectivity for Fe(III) ions among a wide variety of metal ions. The results obtained compared well with those obtained using atomic absorption spectrometry.

Bacteriological quality of bottled water obtained from Mexico City small water purification plants: Incidence and identification of potentially pathogenic nontuberculous mycobacteria species

The aim of this study was to determine the bacteriological quality of bottled water samples obtained from small purification plants located in Mexico City and to identify potentially pathogenic nontuberculous mycobacteria (NTM) species found in these samples. All 111 samples analyzed were positive for aerobic mesophilic bacteria (AMB) and 46 (41.4%) did not comply with Mexico's Official Guidelines. Sixty-nine (62.1%) and 23 (20.7%) water samples were positive for total coliforms (TC) and fecal coliforms (FC), respectively. A total of 81 (72.9%) of the water samples exceeded the maximum allowed limit stipulated in the guideline. Thirty-three (29.7%) of the purified water samples were positive for NTM, being recovered a total of 40 isolates. These NTM isolates were identified using three molecular markers (hsp65, rrs and rpoB genes) which corresponded to the fast-growing mycobacteria M. chelonae (n = 12), M. porcinum (n = 8), M. senegalense (n = 5), M. abscessus (n = 4), M. septicum (n = 4), M. wolinskyi (n = 3), M. mucogenicum (n = 2), M. fortuitum (n = 1) and M. sp. (n = 1). In seven purified water samples, two different NTM species were isolated simultaneously. Overall, these results showed that most of the purified bottled water samples analyzed in this study had unsatisfactory microbiological quality and some harbored NTM associated with illness. Our data could hasten health authorities to intensify efforts in the routine monitoring of activities in the purified bottled water industry in order to supply safe and healthy water to the public.

Improved Retrieval of Ice and Open Water From Sequential RADARSAT-2 Images

In this paper, we present a new technique for automated detection of ice and open water from sequential RADARSAT-2 ScanSAR dual-polarization HH–HV images. The technique is based on combining a previously developed approach to ice and water detection applied to single synthetic aperture radar (SAR) images with the ice motion information derived from sequential SAR images. To evaluate the new approach, it was applied to 736 SAR image pairs acquired in 2013. Compared with the previous approach, the new approach produced an increase in the fraction of correctly classified water samples from 57.7% to 72.6% while the fraction of correctly classified ice samples did not change appreciably. The overall accuracy stayed at a high level exceeding 99.8%, when compared against the Canadian Ice Service Image Analysis pure ice and water samples. Verification results for different regions and months showed that the detection accuracy exceeds 99.5% for the most regions and months. The proposed approach can also assign enhanced quality to ice and water retrievals found in the reference image. The results are particularly relevant in light of the upcoming Canadian RADARSAT Constellation Mission which will significantly increase the amount and frequency of SAR observations over the Arctic region.

The step-edge type HTS rf SQUID coupling with a LC circuit in ultra-low field NMR system

The step-edge type high temperature superconductor (HTS) radio frequency (rf) superconducting quantum interference devices (SQUIDs) were fabricated from YBa2Cu3O7−δ thin films with a field sensitivity of 66 fT/Hz1/2. Even though the sensitivity of the rf SQUID sensor used in the experiments was degraded to 77 fT/Hz1/2 in the magnetic shielded room (MSR), the performance of the rf SQUID sensor was good enough for the ultra-low field (ULF) nuclear magnetic resonance (NMR) experiments at a measurement field of 61.5 μT. With the help of a strictly controlled fast switching circuit and a coupled LC circuit which acted as flux transformer, the signal-to-noise ratio (SNR) of the rf SQUID-based ULF NMR system with different operating points was measured. The optimum SNR was 40 dB which increased significantly by coupling an input coil closely beneath the rf SQUID sensor. The extracted 1/T1 value for pure water sample at 23 ∘C showed the rf SQUID based ULF NMR was an effective system for ULF NMR researches. All above, the direct coupled method and the control circuit show a great potential in the future rf SQUID-based ULF NMR &MRI system.

Water-dispersible pH/thermo dual-responsive microporous polymeric microspheres as adsorbent for dispersive solid-phase extraction of fluoroquinolones from environmental water samples and food samples

Multifunctional polymeric microspheres were prepared using hyper-cross-linking chemistry combined with surface-initiated atom transfer radical polymerization. The synthesized microspheres exhibited good water dispersibility, a high surface area, and pH/thermo dual-responsiveness. Fluoroquinolones (FQs), which contains a hydrophilic piperazine ring and hydrophobic fluorine atoms, were used as target analytes to assess the performance of the microspheres as a sorbent for dispersive solid-phase extraction (d-SPE). The d-SPE experimental parameters, including extraction time, amount of microspheres, extraction temperature, and sample solution pH, as well as the desorption conditions, were systematically studied. Coupled with LCMS/MS, an analytical method for analysis of trace-level FQs in water samples was developed and validated. Under optimal conditions, linearity with correlation coefficients (r) of >0.99 was achieved in the concentration range of 0.02–10 μg L−1. The limits of detection and quantification for the selected FQs were 5.0–6.7 and 12–20 ng L−1, respectively. High recovery values (93.1%–97.2%), a high enrichment factor (˜180), and good precision (RSD < 8%, n = 6) were obtained for FQ determination in spiked purified water samples. It was proposed that hydrophilic–hydrophobic transition induced by stretching and shrinking of polymer chains under different pH and temperature conditions offered good control of the surface wettability and altered the extraction behavior. The developed method was validated and was successfully applied to the analysis of FQs in environmental water samples, meat and milk samples. These results demonstrated that the water-dispersible polymeric microspheres have good potential for use in separation and extraction techniques.