Environmental Wastewater Samples Research Articles

Animal Shelter Wastewater Sampling for Pathogens With Epidemic Potential

Canine distemper virus (CDV), canine parvovirus (CPV), and Streptococcus zooepidemicus (S. zoo) represent a range of infectious agents that can cause epidemic disease in dogs, particularly those housed in animal shelters. Outbreaks of disease associated with these agents are relatively common in shelters, resulting in isolation, quarantine, euthanasia, and in some cases, shelter closure in efforts to manage the outbreak. In recent years, outbreaks of CDV and S. zoo have been particularly challenging for shelters in Arizona. Wastewater-based epidemiology (WBE) has proven useful in disease monitoring and outbreak prediction in human populations, including congregate locations, and we hypothesized that it may also be useful in surveillance and prediction for agents responsible for either gastrointestinal (GI) or respiratory disease in shelter animals. Our specific aims were to develop and validate a protocol for detecting infectious agents from wastewater samples collected from shelter run sections and to investigate associations with agent burden and counts of animals with clinical signs. Once protocols for sampling and preparation were optimized, environmental wastewater samples were collected weekly between November 2023 and April 2024 at a large open intake municipal animal shelter in Phoenix, Arizona. The samples were collected from seven drains located in seven run sections in three separate buildings, and were evaluated for the presence of the three agent nucleic acids using quantitative, multiplex PCR. The counts of dogs actively showing GI and respiratory symptoms, graded as mild, moderate, and severe, were collected the afternoon of the day of sampling. Biosafety committee approval was granted for the viruses in this study. Shedding of CPV was found to be widespread and variable over time. S. zoo was detected five times on five different weeks in five different run sections. CDV was found once. There were only six dogs reported with GI signs during the study period. Counts of respiratory disease ranged from 42-132 dogs per run section with most cases being mild in severity and reported in the isolation run section. There is no apparent association between counts of either respiratory or GI cases and the three agents detected through wastewater sampling. During the study there was a single incident of a S. zoo PCR positive dog being isolated and later dying at the shelter. S. zoo was detected through wastewater sampling the week prior to the incident, however, in a run section located in a different building than where the PCR positive dog was housed. To the authors’ knowledge, this study is the first of its kind to develop protocols to detect critical pathogens in wastewater samples from an animal shelter. CPV has been the pathogen most frequently detected, which we speculate may be largely due to the shedding typically observed in dogs post-vaccination, given the absence of GI signs. Further investigation is warranted to better characterize the absence of amplifiable CDV nucleic acids and to examine these samples for other common shelter pathogens.

"Novel Spectrophotometric Determination of Isopropamide Iodide in Pharmaceutical Formulations and Environmental Wastewater Samples: Application to Content Uniformity Testing"

"Novel Spectrophotometric Determination of Isopropamide Iodide in Pharmaceutical Formulations and Environmental Wastewater Samples: Application to Content Uniformity Testing"

Fluorescence sensing and adsorption kinetics of Gd-doped AgInS2 I-III-VI quantum dots – A case study of Ag+ ions interactions

The poor fluorescence properties of magneto-fluorescent paramagnetic-ion (Gd, Mn, or Co) doped I-III-VI quantum dots (QDs) at higher paramagnetic-ion doping concentrations have limited their use in magnetic-driven water-based applications. This work presents, for the first time, the use of stable magneto-fluorescent Gd-doped AgInS2 QDs at high Gd mole ratios of 16, 20, and 30 for the fluorescence detection and adsorption of Ag+ ions in water environments. The effect of pH, initial concentration, contact time, and adsorbent dosage were systematically evaluated. The AgInS2 QDs with the least Gd mole ratio (16) exhibited the best fluorescence characteristics (LOD = 0.88, R2 = 0.9549) while all materials showed good adsorption properties under optimized conditions (pH of 2, initial concentration of 30 ppm, contact time of 10 min and adsorbent dosage of 0.02 g) and a pseudo 2nd order reaction was followed. The adsorption mechanism was proposed to be a combination of ion-exchange, electrostatic interaction, complexation, and diffusion processes. Application in environmental wastewater samples revealed complete removal of Ag + ions alongside Ti2+ Pb2+, Ni2+, Cr3+, and Zn2+ ions.

Determination of the water-soluble polymer poly(ethyleneimine) (PEI) in wastewater by continuous-flow off-line pyrolysis GC/MS

Reliable identification and quantification of water-soluble synthetic polymers (WSSP), such as polyethyleneimine (PEI), is crucial for understanding their potential impact on certain ecological environments. Therefore, this study proposes an analytical method combining on-line and off-line pyrolysis GC/MS to investigate the pyrolytic degradation. mechanism of branched PEI and develop a calibration method using specific pyrolysis. products, including methylpyrazine, dimethylpyrazine, ethylmethylpyrazine, trimethylpyrazine, methylpropylpyrazine and ethyldimethylpyrazine, for the. quantification of PEI in environmental wastewater samples. The developed analytical. method shows adequate linearity for all molecular ions of the specific pyrolysis. products, with a determination coefficient ranging from 0.95 to 0.98 for the range of 10–500 μg PEI. The limit of quantification for this method lies between 1 and 10 μg/L of PEI. The accuracy (absolute recovery 71–95%) and reproducibility (RSD < 30%) were. evaluated by multiple spiking/recovery experiments at a PEI level of 500 μg. Using this. method for samples collected from different wastewater treatment plants in Germany. reveals a significant emission of PEI to the aquatic environment with concentrations. ranging from 0.08 mg L-1–0.55 mg L-1, and thus demonstrating its applicability in. environmental studies. To the best of our knowledge, this is the first report on the. occurrence of PEI in environmental samples.

Draft genome sequences of rare Lelliottia nimipressuralis strain MEZLN61 and two Enterobacter kobei strains MEZEK193 and MEZEK194 carrying mobile colistin resistance gene mcr-9 isolated from wastewater in South Africa

Antimicrobial-resistant bacteria of the order Enterobacterales are emerging threats to global public and animal health, leading to morbidity and mortality. The emergence of antimicrobial-resistant, livestock-associated pathogensis a great public health concern. The genera Enterobacter and Lelliottia are ubiquitous, facultatively anaerobic, motile, non-spore-forming, rod-shaped Gram-negative bacteria belonging to the Enterobacteriaceae family and include pathogens of public health importance. Here, we report the first draft genome sequences of a rare Lelliottia nimipressuralis strain MEZLN61 and two Enterobacter kobeistrains MEZEK193 and MEZEK194 in Africa. The bacteria were isolated from environmental wastewater samples. Bacteria were cultured on nutrient agar, and the pure cultures were subjected to whole-genome sequencing. Genomic DNA was sequenced using an Illumina MiSeq platform. Generated reads were trimmed and subjected to de novo assembly. The assembled contigs were analysed for virulence genes, antimicrobial resistance genes, and extra-chromosomal plasmids, and multilocus sequence typing was performed. To compare the sequenced strains with other, previously sequenced E. kobei and L. nimipressuralis strains, available raw read sequences were downloaded, and all sequence files were treated identically to generate core genome bootstrapped maximum likelihood phylogenetic trees. Whole-genome sequencing analyses identified strain MEZLN61 as L. nimipressuralis and strains MEZEK193 and MEZEK194 as E. kobei. MEZEK193 and MEZEK194 carried genes encoding resistance to fosfomycin (fosA), beta-lactam antibiotics (blaACT-9), and colistin (mcr-9). Additionally, MEZEK193 harboured nine different virulence genes, while MEZEK194 harboured eleven different virulence genes. The phenotypic analysis showed that L. nimipressuralis strain MEZLN61 was susceptible to colistin (2 μg/mL), while E. kobei MEZEK193 (64 μg/mL) and MEZEK194 (32 μg/mL) were resistant to colistin. The genome sequences of strains L. nimipressuralis MEZLN6, E. kobei MEZEK193, and E. kobei MEZEK194 will serve as a reference point for molecular epidemiological studies of L. nimipressuralis and E. kobeiin Africa. In addition, this study provides an in-depth analysis of the genomic structure and offers important information that helps clarify the pathogenesis and antimicrobial resistance of L. nimipressuralis and E. kobei. The detection of mcr-9, which is associated with very low-level colistin resistance in Enterobacter species, is alarming and may indicate the undetected dissemination of mcr genes in bacteria of the order Enterobacterales. Continuous monitoring and surveillance of the prevalence of mcr genes and their associated phenotypic changes in clinically important pathogens and environmentally associated bacteria is necessary to control and prevent the spread of colistin resistance.

Ion-pair extractive spectrophotometric determination of isopropamide iodide in pharmaceutical formulations and environmental wastewater samples using Bromo phenol blue

A simple, accurate and sensitive spectrophotometric method was developed for the determination of isopropamide iodide in pharmaceutical formulations and environmental wastewater samples. The method was based on the formation of ion-pair between isopropamide iodide and bromophenol blue (BPB). The colored product was extracted into chloroform and measured spectrophotometrically at 600 nm. Beer’s law was obeyed in the concentration range of 2.0-20.0 μg/mL with molar absorptivity and Sandell’s sensitivity of 3.17 × 104 L /mol. cm and 15.15 ng/.cm2 respectively. The relative standard deviation (RSD) is better than 1.5. The method was applied successfully to the determination of isopropamide iodide in environmental wastewater samples and in pharmaceutical formulations (tablets).

Fabrication of a Label‐free Femtomolar Electrochemical Mercury Ion Biosensor Based on Oligonucleotide Receptor Layers Hybridized with Multi‐walled Carbon Nanotubes

AbstractThe feasibility of designing a highly selective and sensitive label‐free cost‐effective biosensor to determine Hg2+ ions using gold electrodes functionalized with short‐chain, thymine‐rich, ss‐DNA oligonucleotides wrapped MWNTs is examined. The potassium ferricyanide was used as a redox marker for analytical signal generation. Biosensor response was based on the difference in the electrochemical signal before and after subjecting it to a sample containing Hg2+ ions. The lowest detection limit of 1 femtomolar (fM) of mercury ions was observed in the aqueous medium, together with good selectivity against common metal cations. The method developed was successfully applied for the determination of Hg2+ ions in environmental waste water samples.

On-line solid-phase extraction of pharmaceutical compounds from wastewater treatment plant samples using restricted access media in column-switching liquid chromatography-tandem mass spectrometry

An on-line solid phase extraction using a lab-made restricted access media (RAM) was developed as sample preparation procedure for determination of the pharmaceutical compounds caffeine (CAF), carbamazepine (CBZ), norfloxacin (NOR), ciprofloxacin (CIP), fluoxetine (FLX) and venlafaxine in wastewater treatment plant samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS). This method is suitable for use in routine of analysis, avoiding cross-contamination and requiring only a small sample volume (50 µL), with minimal handling.The method was validated according to international guidelines. The chromatographic efficiency was evaluated using peak resolution and asymmetry parameters. Carryover was also evaluated, in order to ensure reliability of the analysis and the ability to reuse the cartridge. Satisfactory linearity (r2 > 0.99) was obtained for all the compounds. The intra- and inter-day precision values were lower than 5.79 and 14.1%, respectively. The limits of detection ranged from 0.01 to 3 µg L−1 and the limits of quantification were from 0.1 to 5 µg L−1. The method was applied to 20 environmental wastewater samples, with caffeine being the most widely detected compound, at the highest concentration of 392 µg L−1, while other compounds were detected in fewer samples at lower concentrations (up to 9.60 µg L−1). The lab-made modification is a cheaper option for on-line sample preparation, compared to commercially available on-line SPE cartridges and RAM columns. Moreover, a high-throughput procedure was achieved, with an analysis time of 16 min including sample preparation and chromatographic separation. The same RAM column was applied over 200 injections including method optimization, validation and application in wastewater samples without loss of analytical response.

Eco- Friendly Ultraviolet Spectrophotometric Determination of Allopurinol in Pharmaceutical Preparations and Environmental Wastewater Samples: Application to Content Uniformity Testing

A simple, economical and sensitive UV spectrophotometric method has been developed for the determination of allopurinol in environmental wastewater samples and, pharmaceutical preparations which shows maximum absorbance at 250 nm in distilled water. Beer’s law was obeyed in the range of 1 - 20 μg/ ml, with molar absorptive of 0.628 x104 l/mol.cm L.mol-1.cm-1 .The method was successfully applied to the determination of allopurinol in some pharmaceutical formulations (tablets) and industrial wastewater samples. The proposed method was validated by sensitivity and precision which proves suitability for the routine analysis of allopurinol in true samples.

Eco- Friendly Method for the Estimation of Warfarin Sodium in Pharmaceutical Preparations and Environmental Wastewater Samples

A simple, precise, accurate, rapid, economical and sensitive ultraviolet spectrophotometric method has been developed for the determination of warfarin sodium in pharmaceutical preparations and environmental wastewater samples, which shows maximum absorbance at 310 nm in distilled water. Beer’s law was obeyed in the range of 2-30μg/ ml ,with molar absorptivity of 1.1 ×104 L.mol-1.cm-1 , relative standard deviation of the method was less than 1.8%, and accuracy (average recovery %) was 100 ± 1.0 . The method was successfully applied to the determination of warfarin sodium in some pharmaceutical formulations (Tablets) and industrial wastewater samples. The proposed method was validated by sensitivity and precision which proves suitability for the routine analysis of warfarin sodium in true samples.

Synthesis and characterization of FSB@Fe3O4 composites and application in removal of indigo carmine dye from industrial wastewaters.

The syntheses and characterization of fish scale biochar magnetic composites (FSB@Fe3O4) and their applications in the removal of indigo carmine dye from effluents are described. Preparation of the fish scale biochar magnetic composites, FSB@400 °C-Fe3O4, FSB@600 °C-Fe3O4, and FSB@800 °C-Fe3O4, was done following the chemical co-precipitation method. The adsorbents were characterized using peak optical absorbance, functional groups, magnetic strength, surface morphology, particle size, elemental compositions, surface charge, surface area, thermal stability, and crystalline phase, using ultraviolet-visible spectroscopy (UV-vis spec), Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometry (VSM), transmission electron microscopy/scanning electron microscopy (TEM/SEM), energy dispersive X-ray (EDX), point of zero charge pH (pHpzc), Brunauer-Emmett-Teller (BET), thermo-gravimetric analysis (TGA), and powder x-ray diffraction (PXRD) techniques, correspondingly. The potential of magnetic composites for the abstraction of indigo carmine dye from wastewater was determined as a function of the initial concentration of indigo carmine dye, contact time, dye solution pH, adsorbent dosage, and solution temperature. The results demonstrated that the quantity (q) of indigo carmine dye adsorbed onto magnetic composites improved with a rise in initial dye concentration, adsorbent load, and solution temperature. Conversely, lower quantities of adsorbed dye were recorded at higher pH levels. The data fitted a pseudo-second-order kinetic model. The Langmuir isotherm gave the best fit (Langmuir>Freundlich>Redlich-Peterson>Toth>Hill>Sips>Temkin) suggesting a uniformly monolayer adsorption. Adsorption of environmental wastewater samples revealed that all the adsorbents can be used to effectively treat industrial wastewaters. The recycling data established that the adsorbents could be used for five consecutive cycles without significant loss of adsorption capacities.

A POC device for on-the-spot detection of hexavalent chromium in wastewater

The present work describes a novel handheld pocket-friendly device for on the spot detection of chromium. The device gives not only qualitative but also the quantitative determination of chromium in environmental wastewater samples. The qualitative detection can be made visually by the naked eye while for the quantitative detection a colorimetric device has been fabricated in-house. The system comprises a source, sample holder, detector, and a microcontroller-processing unit with a display unit. The method involves the detection of hexavalent chromium Cr (VI) in aqueous systems by using citrate-capped silver nanoparticle (C-AgNPs) leading to a reduction of Cr (VI) to Cr (III). The citrate capped silver nanoparticles were synthesized and characterized using a blend of characterization techniques like ultra-violet visible (UV-Vis) spectrophotometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. The device performance remained unaffected even in the presence of various interfering cations present in the wastewater. The device was tested, and results were calibrated with standard atomic absorption spectroscopy (AAS), it showed linearity from 0.01-0.7 ppm for wastewater samples tested with spiking different known concentrations of chromium. The limit of detection (LOD) of the method is 26 ppb and the limit of quantitation (LOQ) of 79 ppb. The development of a low-cost, simple colorimeter employing the same sensor principle underlines the on-site applicability of this method.

EcoToxModules: Custom Gene Sets to Organize and Analyze Toxicogenomics Data from Ecological Species.

Traditional results from toxicogenomics studies are complex lists of significantly impacted genes or gene sets, which are challenging to synthesize down to actionable results with a clear interpretation. Here, we defined two sets of 21 custom gene sets, called the functional and statistical EcoToxModules, in fathead minnow (Pimephales promelas) to (1) re-cast predefined molecular pathways into a toxicological framework and (2) provide a data-driven, unsupervised grouping of genes impacted by exposure to environmental contaminants. The functional EcoToxModules were identified by re-organizing KEGG pathways into biological processes that are more relevant to ecotoxicology based on the input from expert scientists and regulators. The statistical EcoToxModules were identified using co-expression analysis of publicly available microarray data (n = 303 profiles) measured in livers of fathead minnows after exposure to 38 different conditions. Potential applications of the EcoToxModules were demonstrated with two case studies that represent exposure to a pure chemical and to environmental wastewater samples. In comparisons to differential expression and gene set analysis, we found that EcoToxModule responses were consistent with these traditional results. Additionally, they were easier to visualize and quantitatively compare across different conditions, which facilitated drawing conclusions about the relative toxicity of the exposures within each case study.

Adsorptive removal of trace sulfonamide antibiotics by water-dispersible magnetic reduced graphene oxide-ferrite hybrids from wastewater.

A one-pot solvothermal synthesis method was developed to prepare reduced graphene oxide (RGO) supported ferrite hybrids using graphite oxide and metal ions (Fe(3+)) as starting materials. The as-prepared composites were characterized by transmission electron microscopy(TEM), Fourier transform infrared spectrophotometer (FT-IR), X-ray powder diffraction pattern(XRD) and vibrating sample magnetometer (VSM). It was shown that Fe3O4 nanoparticles with a uniform size of ∼35nm were anchored on RGO nanosheets. Importantly, the obtained nanocomposites are effective adsorbents for the determination of three sulfonamides in wastewater. Several parameters affecting the extraction efficiency were optimized, including amount of adsorbent, extraction time, pH and desorption conditions. Compared with other adsorbents, the as-prepared RGO-Fe3O4 showed the better extraction efficiencies for the SAS due to the large surface area of RGO. A linear range from 1 to 200ng/mL was obtained with a high correlation coefficient (R(2)>0.9987), and the limits of detection for three SAs ranged from 0.43 to 0.57ng/mL. This method was successfully applied to the analysis of SAs in environmental wastewater samples, the recoveries in different sample matrices were in the range from 89.1 and 101.7% with relative standard deviations less than 8.6%. It is believed that such composites will find wide applications in the water pretreatment area.

A novel fatty-acid-based in-tube dispersive liquid–liquid microextraction technique for the rapid determination of nonylphenol and 4-tert-octylphenol in aqueous samples using high-performance liquid chromatography–ultraviolet detection

In this study, a novel fatty-acid-based in-tube dispersive liquid–liquid microextraction (FA-IT-DLLME) technique is proposed for the first time and is developed as a simple, rapid and eco-friendly sample extraction method for the determination of alkylphenols in aqueous samples using high-performance liquid chromatography–ultraviolet detection (HPLC–UV). In this extraction method, medium-chain saturated fatty acids were investigated as a pH-dependent phase because they acted as either anionic surfactants or neutral extraction solvents based on the acid–base reaction caused solely by the adjustment of the pH of the solution. A specially designed home-made glass extraction tube with a built-in scaled capillary tube was utilized as the phase-separation device for the FA-IT-DLLME to collect and measure the separated extractant phase for analysis. Nonylphenol (NP) and 4-tert-octylphenol (4-tOP) were chosen as model analytes. The parameters influencing the FA-IT-DLLME were thoroughly investigated and optimized. Under the optimal conditions, the detector responses of NP and 4-tOP were linear in the concentration ranges of 5–4000μgL−1, with correlation coefficients of 0.9990 and 0.9996 for NP and 4-tOP, respectively. The limits of detection based on a signal-to-noise ratio of 3 were 0.7 and 0.5μgL−1, and the enrichment factors were 195 and 143 for NP and 4-tOP, respectively. The applicability of the developed method was demonstrated for the analysis of alkylphenols in environmental wastewater samples, and the recoveries ranged from 92.9 to 107.1%. The extraction process required less than 4min and utilized only acids, alkalis, and fatty acids to achieve the extraction. The results demonstrated that the presented FA-IT-DLLME approach is highly cost-effective, simple, rapid and environmentally friendly in its sample preparation.

Preparation and use of maize tassels' activated carbon for the adsorption of phenolic compounds in environmental waste water samples.

The determination and remediation of three phenolic compounds bisphenol A (BPA), ortho-nitrophenol (o-NTP), parachlorophenol (PCP) in wastewater is reported. The analysis of these molecules in wastewater was done using gas chromatography (GC) × GC time-of-flight mass spectrometry while activated carbon derived from maize tassel was used as an adsorbent. During the experimental procedures, the effect of various parameters such as initial concentration, pH of sample solution, eluent volume, and sample volume on the removal efficiency with respect to the three phenolic compounds was studied. The results showed that maize tassel produced activated carbon (MTAC) cartridge packed solid-phase extraction (SPE) system was able to remove the phenolic compounds effectively (90.84-98.49%, 80.75-97.11%, and 78.27-97.08% for BPA, o-NTP, and PCP, respectively). The MTAC cartridge packed SPE sorbent performance was compared to commercially produced C18 SPE cartridges and found to be comparable. All the parameters investigated were found to have a notable influence on the adsorption efficiency of the phenolic compounds from wastewaters at different magnitudes.

Rapid point-of-use water purification using nanoscale zero valent iron (nZVI) particles

Nanoscale zero-valent iron (nZVI) particles are increasingly being investigated in removing aqueous contaminants. Here, we have demonstrated its inactivation and magnetic removal of bacteria and endotoxins from environmental wastewater samples. Varying dosages (10–1,000 μL) of 0–6 days aged nZVI with a concentration of 5 mg/mL for 2 mL wastewater samples were tested, and relevant removal efficiencies were determined using culturing method for bacteria and limulus amebocyte lysate (LAL) for endotoxins. The supernatants of wastewater samples after reacting with nZVI and subsequent magnetic separations were subjected to spectroscopic, qPCR and DGGE analysis. Overall, high magnetic bacterial removal efficiencies were observed up to 3–4 logs for 1 mL nZVI, while the removal efficiencies decreased sharply down to 0.5 log for 10 μL nZVI. qPCR and DGGE results revealed that higher dosages of nZVI caused severe bacterial cell membrane ruptures, releasing significant amounts of DNA up to 107–108 gene copies/mL when 1 mL nZVI was used. Richer DGGE patterns were observed for higher nZVI dosages. In addition, regardless of the dosages (10–1,000 μL) we have observed more than 90 % removal of endotoxins from the wastewater samples. The described technology has great promise to be used as a point-of-use water purification solution for various purposes.

Fine-tuning mesoporous adsorbent for simultaneous ultra-trace palladium(II) detection, separation and recovery

A simple and sensitive method was applied for determination and extraction of trace level palladium(II) in wastewater by using functionalized mesoporous silica based fine-tuning mesoporous adsorbent. The adsorbent was stable and easy to detect, adsorb and recover Pd(II) ions by charge transfer (intense π–π transition) complexation mechanism. The optimum experimental conditions such as pH, contact time, initial concentration, selectivity and sensitivity, type and amount of eluent for elution and various ionic interferences on detection and sorption were systematically evaluated. The determined maximum sorption capacity was 191.35mg/g. The proposed method was applied successfully for extraction of Pd(II) in environmental wastewater samples.

Polyaniline‐coated Fe3O4 nanoparticles: An anion exchange magnetic sorbent for solid‐phase extraction

In this study, the capability of the prepared polyaniline-coated Fe(3) O(4) nanoparticles for magnetic solid-phase extraction of three parabens from environmental wastewater, cream, and toothpaste samples is presented. Synthesized Fe(3) O(4) nanoparticles were coated with sulfate-doped polyaniline via polymerization of aniline in the presence of Fe(3) O(4) nanoparticles and sulfuric acid. Here, polyaniline-coated Fe(3) O(4) nanoparticles are presented as anion exchange sorbent, which extract anionic form of parabens via anion exchange with dopant of polyaniline. The experimental conditions affecting extraction efficiency were further studied and optimized. The experimental results showed that maximum extraction efficiency can be obtained at 70 mL sample solution of pH 8, extraction and desorption times of 2 and 1 min, respectively, 100 μL of 3% (v/v) acetic acid in acetonitrile as eluent, and 100 mg of the adsorbent. Under these conditions, the linear dynamic ranges were 0.5-100 μg/L with good correlation coefficients (0.998-0.999). The detection limits were in the range of 0.3-0.4 μg/L and the relative standard deviations were less than 2.4 (n = 5) for the three parabens. Finally, this fast and efficient method was further employed for determination of target analytes in cream, toothpaste, and environmental wastewater samples and satisfactory results were obtained.

Specific detection of viable Listeria monocytogenes in Spanish wastewater treatment plants by Fluorescent In Situ Hybridization and PCR

Listeria monocytogenes detection in wastewater can be difficult because of the large amount of background microbiota and the presence of viable but non-culturable forms in this environment. The aim of this study was to evaluate a Fluorescent In Situ Hybridization (FISH) assay combined with Direct Viable Count (DVC) method for detecting viable L. monocytogenes in wastewater samples, as an alternative to conventional culture methods. 16S rRNA sequence data were used to design a specific oligonucleotide probe. In order to assess the suitability of the method, the assays were performed on naturally (n = 87) and artificially (n = 14) contaminated samples and results were compared to those obtained with the isolation of cells on selective media and with a PCR method. The detection limit of FISH and PCR assays was 104 cells/mL without enrichment and 10 cells/mL after enrichment. A total of 47 samples, including 3 samples from effluent sites, yielded FISH positive results for L. monocytogenes. Using DVC-FISH technique, the presence of viable L. monocytogenes cells was detected in 23 out of these 47 FISH positive wastewater samples. PCR and culture methods yielded 27 and 23 positive results, respectively. According to these results, FISH technique has the potential to be used as a sensitive method for the detection and enumeration of L. monocytogenes in environmental wastewater samples.