Graphene oxide-based dispersive solid-phase extraction combined with in situ derivatization and gas chromatography–mass spectrometry for the determination of acidic pharmaceuticals in water

Non-steroidal anti-inflammatory drugs (NSAIDs) in the environment: Updates on pretreatment and determination methods

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used in human and animal health care to reduce persistent inflammation, pain and fever because of their anti-inflammatory, analgesic and antipyretic effects. However, the improper discharge and disposal make it becomes a major contaminant in the environment, which poses a big threat to the ecosystem. For this reason, accurate, sensitive, effective, green, and economic techniques are urgently required and have been rapidly developed in recent years. This review summarizes the advancement of sample preparation technologies for NSAIDs involving solid-phase extraction, solid-phase microextraction, liquid-phase microextraction, QuEChERS, and matrix solid-phase dispersion. Meanwhile, we overview and compare analytical technologies for NSAIDs, including liquid chromatography-based methods, gas chromatography-based methods, capillary electrophoresis, and sensors, particularly the development of liquid chromatography-based methods. Furthermore, we focus on their progress and conduct a comparison between their advantages and disadvantages.

Cellulose-based adsorbents for solid phase extraction and recovery of pharmaceutical residues from water

Cellulose has attracted interest from researchers both in academic and industrial sectors due to its unique structural and physicochemical properties. The ease of surface modification of cellulose by the integration of nanomaterials, magnetic components, metal organic frameworks and polymers has made them a promising adsorbent for solid phase extraction of emerging contaminants, including pharmaceutical residues. This review summarizes, compares, and contrasts different types of cellulose-based adsorbents along with their applications in adsorption, extraction and pre-concentration of pharmaceutical residues in water for subsequent analysis. In addition, a comparison in efficiency of cellulose-based adsorbents and other types of adsorbents that have been used for the extraction of pharmaceuticals in water is presented. From our observation, cellulose-based materials have principally been investigated for the adsorption of pharmaceuticals in water. However, this review aims to shift the focus of researchers to the application of these adsorbents in the effective pre-concentration of pharmaceutical pollutants from water at trace concentrations, for quantification. At the end of the review, the challenges and future perspectives regarding cellulose-based adsorbents are discussed, thus providing an in-depth overview of the current state of the art in cellulose hybrid adsorbents for extraction of pharmaceuticals from water. This is expected to inspire the development of solid phase exraction materials that are efficient, relatively cheap, and prepared in a sustainable way.

Molecularly imprinted wax

The development of an elution-free solid-phase extraction (SPE) process is of special interest in sample pretreatment. Due to the phase-change merits at relatively low temperatures and easy dissolution in n-hexane, wax spheres show great potential in this field. However, the conventional wax spheres possess a low affinity towards the target analytes when they are used as SPE adsorbents. In this study, using octadecanoic acid as the functional monomer and wax as the matrix, molecularly imprinted wax (MIW) spheres were successfully prepared. The obtained MIW spheres displayed remarkable molecular recognition ability and high selectivity towards the template. Interestingly, the as-synthesized molecularly imprinted wax (MIW) could be dissolved in n-hexane or melted by heating for subsequent fluorescence and mass spectrum analysis without the target elution process. Moreover, the melted MIW exhibited high repeatability, sensitivity and specificity for solid-state fluorescence detection. We believe that the imprinting method presented in this study will open a new window in analytical chemistry.

Occurrence, detection and ecotoxicity studies of selected pharmaceuticals in aqueous ecosystems- a systematic appraisal

Pharmaceutical compounds (PCs) have globally emerged as a significant group of environmental contaminants due to the constant detection of their residues in the environment. The main scope of this review is to fill the void of information on the knowledge on the African occurrence of selected PCs in environmental matrices in comparison with those outside Africa and their respective toxic actions on both aquatic and non-aquatic biota through ecotoxicity bioassays. To achieve this objective, the study focused on commonly used and detected pharmaceutical drugs (residues). Based on the conducted literature survey, Africa has the highest levels of ciprofloxacin, sulfamethoxazole, lamivudine, acetaminophen, and diclofenac while Europe has the lowest of all these PC residues in her physical environments. For ecotoxicity bioassays, the few data available are mostly on individual groups of pharmaceuticals whereas there is sparsely available data on their combined forms.

Self-supported 3D reduced graphene oxide for solid-phase extraction: An efficient and low-cost sorbent for environmental contaminants in aqueous solution

A 3D reduced graphene oxide (3D-rGO), a self-supported, efficient, and low-cost sorbent, was synthesised and employed in a solid-phase extraction (SPE) cartridge. As a proof of concept, it was applied to remove diclofenac from aqueous solution. After applying statistical methods to systematically investigate key parameters for optimizing the 3D-rGO cartridge performance, it reached removal and elution efficiencies of 100 % and 90 %, respectively. This SPE cartridge presented advantages compared to traditional ones as the smaller amount of material into the cartridge (mass twenty times smaller), in addition to the ability of eliminating sorbent preconditioning, reducing the use of solvents, and making the process environmentally friendly with a faster operation. Also, it presented improved reproducibility after several cycles of reuse, and finally a lower cost of production unveiled by a cost-benefit analysis. Analysis with scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, Raman, and Fourier transform infrared spectroscopy in attenuated total reflectance mode suggested that the 3D framework morphology with a high content of carbon at the surface and some residual oxygen-containing groups are the protagonists in this performance. Therefore, 3D-rGO has the potential to be a highly efficient sorbent in analytical procedures using SPE for environmental contaminants in water and effluent samples.

Development of a magnetic dispersive solid phase extraction method by employing folic acid magnetic nanoparticles as an effective, green, and reliable sorbent followed by dispersive liquid-liquid microextraction for the extraction and preconcentration of seven pesticides from fruit juices

Folic acid magnetic nanoparticles have been prepared and utilized as an effective and reliable sorbent in magnetic dispersive solid phase extraction combined with dispersive liquid-liquid microextraction for the extraction of seven pesticides from different juices before their determination by gas chromatography-flame ionization detector. The sorbent is prepared through ball milling process using a proper mixture of folic acid and magnetic iron oxide. Characterization of the sorbent was done with X-ray diffraction pattern, scanning electron microscopy, and vibrating sample magnetometry. In the current study, limits of detection were in the range 0.12-0.33 μg L^-1. Relative standard deviations at a concentration of 40 μg L^-1 of each analyte were in the ranges of 2.15-5.14% for intra-day (n = 6) and 3.78-6.91% for inter-day (n = 4) precisions. Extraction recoveries and enrichment factors were obtained in the ranges of 70-88 % and 566-708, respectively. The performance of the method was evaluated by determination the selected pesticides in different samples. Graphical Abstract.

Occurrence of contaminants of emerging concern in surface waters from Paraopeba River Basin in Brazil: seasonal changes and risk assessment

This study describes the application of gas chromatography coupled to mass spectrometry (GC-MS) to evaluate the occurrence of 12 CECs-contaminants of emerging concern (bisphenol A, diclofenac, 17β-estradiol, estriol, estrone, 17α-ethinylestradiol, gemfibrozil, ibuprofen, naproxen, 4-nonylphenol, 4-octylphenol, and acetaminophen) in surface waters from Paraopeba River Basin, Minas Gerais State, Brazil. The analytical procedure was validated and applied to 60 surface water samples collected across four sampling campaigns along the upper and middle watershed. Methods for CECs determination involved sample filtration, and solid-phase extraction (SPE) with subsequent derivatization of the target compounds prior to their analysis by GC-MS. The LOQ varied from 3.6 to 14.4 ng/L and extraction recoveries ranged from 46.1 to 107.1% for the lowest spiked concentration level (10 ng/L). The results showed a profile of spatial distribution of compounds, as well as the influence of rainfall. Ibuprofen (1683.9 ng/L), bisphenol (1587.7 ng/L), and naproxen (938.4 ng/L) occurred in higher concentrations during the rainy season, whereas during the dry season, the concentrations of bisphenol (1057.7 ng/L), estriol (991.0 ng/L), and estrone (978.4 ng/L) were highlighted. The risk assessment of human exposure shows that for most contaminants, the concentration is well below the estimated thresholds for chronic toxicity from water intake. However, estradiol and 17α-ethinylestradiol showed concentrations in the same order of magnitude as the guide values estimated for babies.

Sample bottle coated with sorbent as a novel solid-phase extraction device for rapid on-site detection of BTEX in water

Solid-phase extraction (SPE) is a popular technique for environmental sample pretreatment. However, SPE usually requires complex sample pretreatment processes, which is time-consuming and inconvenient for real-time and on-site monitoring. Herein, a solvent-free, rapid, and user-friendly SPE device was developed by coating the polydimethylsiloxane (PDMS)/divinylbenzene (DVB) sorbent on the inner wall of a sample bottle. The extraction process and desorption process were both carried out in the bottle. The analytes trapped in the sorbent were thermally desorbed and simultaneously sucked out from the bottle by an air sampling tube equipped on field-portable GC-MS. Different to previous work, the sample pretreatment process didn't require any complicated and time-consuming steps, such as centrifugation or filtration. The total analysis time for each sample was less than 25 min, which was feasible for rapid on-site detection, and thus avoided the losses and contamination of samples in conventional sample storage and transportation processes. Under optimal conditions, the proposed SPE method exhibited wide linear ranges, low detection limits (0.010-0.036 μg L^-1, which were much lower than the maximum levels restricted by the US Environmental Protection Agency and the Chinese GB3838-2002 standard), good intra-bottle repeatability (6.13-7.17%, n = 3) and satisfactory inter-bottle reproducibility (4.73-6.47%, n = 3). Finally, the method was successfully applied to the rapid detection of BTEX in the field. The recoveries of BTEX in spiked water samples ranged from 89.1% to 116.2%. This work presents a novel SPE approach for rapid on-site monitoring in water samples.

Facile Synthesis of Porous Carbon for the Removal of Diclofenac Sodium from Water

In this work, a series of porous carbon materials (PCs) were obtained at different carbonization temperatures (800, 900, 1000, and 1100 °C) by a simple and fast solvent-free method. Moreover, the feasibility of PCs as reliable and efficient adsorbents to capture diclofenac sodium (DCF) from the water was evaluated. Notably, porous carbon (PC) prepared at 1000 °C (PC-1000) was found to be the best candidate for the adsorption of DCF. Remarkably, adsorption equilibrium was achieved within 3 h, which followed a pseudo-second-order kinetic model with a high correlation coefficient (R ² > 0.994). Furthermore, experimental data obtained from adsorption isotherm indicated that the capture of DCF onto PC-1000 followed the Langmuir adsorption model (R ² > 0.997), wherein its maximum adsorption capacity was calculated to be 392 mg/g. In addition, based on the results obtained from the zeta potential of PC-1000 under different pH and the adsorbed quantity of DCF along with functional groups created on the surface of PC-1000, electrostatic and H-bonding interactions were proposed as the possible adsorption mechanisms. Due to its high stability and excellent reusability, PC-1000 has been testified as a promising candidate for removing DCF from contaminated water.

Novel nanofibers mat as an efficient, fast and reusable adsorbent for solid phase extraction of non-steroidal anti-inflammatory drugs in environmental water

Core-shell polyaniline/polyacrylonitrile nanofibers mat (PANI/Pan NFsM) was prepared for extraction of hydrophilic non-steroidal anti-inflammatory drugs (NSAIDs) in environmental water. Superior adsorption and desorption performance of PANI/Pan NFsM was confirmed by both static and dynamic adsorption/desorption experiments. These properties proved PANI/Pan NFsM was a potentially efficient and fast solid phase extraction (SPE) adsorbent for NSAIDs. Under the optimized conditions, only 3 mg of PANI/Pan NFsM could easily extract eight target analytes in 10 mL of water sample without any pre-treatment, and the analytes retained on NFsM could be easily eluted by 500 μL of 1% acetic acid methanol for direct UPLC-MS/MS analysis. In addition, each piece of PANI/Pan NFsM could be reused for at least 20 times without performance decline. Possible adsorption mechanisms were also proposed. Practical feasibility was validated through the actual sample analysis.

Analysis of diclofenac in water samples using in situ derivatization-vortex-assisted liquid-liquid microextraction with gas chromatography-mass spectrometry

A novel micro-extraction technique for a rapid and sensitive analysis of diclofenac (DCF) in water samples has been developed. DCF was derivatized and extracted simultaneously using vortex-assisted liquid-liquid micro-extraction (VALLME) prior to gas chromatography with mass spectrometry detection. The effects of extraction solvent volume, extraction and derivatization time and ionic strength of the sample were studied using 23 factorial experimental design. The optimum extraction conditions were as follows: 200 μL of chloroform, 25 μL of N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) derivatization reagent, vortex extraction and derivatization time 5 min at 3000 rpm. The extraction recovery for different fortification levels was 98 %. Also, the proposed micro-extraction method exhibited results comparable with the solid phase extraction of real water samples. The proposed one-step VALLME and derivatization method is simpler and faster than the conventional extraction and derivatization methods used for the determination of DCF in real water samples.

Preconcentration of Trace Neonicotinoid Insecticide Residues Using Vortex-Assisted Dispersive Micro Solid-Phase Extraction with Montmorillonite as an Efficient Sorbent

In this work, we investigated montmorillonite for adsorption of neonicotinoid insecticides in vortex-assisted dispersive micro-solid phase extraction (VA-d-μ-SPE). High-performance liquid chromatography with photodiode array detection was used for quantification and determination of neonicotinoid insecticide residues, including thiamethoxam, clothianidin, imidacloprid, acetamiprid, and thiacloprid. In this method, the solid sorbent was dispersed into the aqueous sample solution and vortex agitation was performed to accelerate the extraction process. Finally, the solution was filtered from the solid sorbent with a membrane filter. The parameters affecting the extraction efficiency of the proposed method were optimized, such as amount of sorbent, sample volume, salt addition, type and volume of extraction solvent, and vortex time. The adsorbing results show that montmorillonite could be reused at least 4 times and be used as an effective adsorbent for rapid extraction/preconcentration of neonicotinoid insecticide residues. Under optimum conditions, linear dynamic ranges were achieved between 0.5 and 1000 ng mL^-1 with a correlation of determination (R²) greater than 0.99. Limit of detection (LOD) ranged from 0.005 to 0.065 ng mL^-1, while limit of quantification (LOQ) ranged from 0.008 to 0.263 ng mL^-1. The enrichment factor (EF) ranged from 8 to 176-fold. The results demonstrated that the proposed method not only provided a more simple and sensitive method, but also can be used as a powerful alternative method for the simultaneous determination of insecticide residues in natural surface water and fruit juice samples.

Identification, characterization and distribution of terpene indole alkaloids in ethanolic extracts of Catharanthus roseus using high-performance liquid chromatography/electrospray ionization quadrupole time-of-flight tandem mass spectrometry and the study of their geographical variation

RATIONALE

Catharanthus roseus is a well-known dicotyledonous medicinal plant containing diverse classes of bioactive terpene indole alkaloids (TIAs), in particular the anticancer agents vinblastine and vincristine. In view of the commercial importance of these compounds there is an urgent need to develop an accurate and reliable method for the screening of TIAs from C. roseus.

METHODS

A method for the separation and characterization of these compounds was developed using high-performance liquid chromatography coupled with positive electrospray ionization quadrupole time-of-flight tandem mass spectrometry (HPLC/ESI-QTOF-MS/MS). Chromatographic separation of TIAs was carried out using a Thermo Betasil C8 column (250 mm × 4.5 mm, 5 μm) at 25°C using 0.1% formic acid in water and acetonitrile.

RESULTS

Diagnostic fragmentation pathways for vinpocetine, vindesine, catharanthine, vinblastine, vindoline and vincristine were established on the basis of their product ions. A total of 72 TIAs were detected of which 11 were unambiguously identified by comparison with their standards, and the remaining 61 were tentatively identified. The geographical distribution of the TIAs in ethanolic extracts of 30 samples of C. roseus collected from five states of India was studied using principal component analysis (PCA).

CONCLUSIONS

The developed analytical method together with diagnostic fragment patterns were used to rapidly and effectively identify targeted and untargeted TIAs in C. roseus. A PCA study of the results obtained was used to discriminate among the C. roseus samples.

A molecularly imprinted polymer coupled with high-performance liquid chromatography-UV for the determination of albendazole in plasma and urine samples: CCD-RSM design

The present study attempted to develop a fast and sensitive ultrasound-assisted-dispersive-micro-solid phase extraction method for the separation and preconcentration of albendazole from plasma and urine samples.

Facile synthesis of amine-functional reduced graphene oxides as modified quick, easy, cheap, effective, rugged and safe adsorbent for multi-pesticide residues analysis of tea

Amine-functional reduced graphene oxide (amine-rGO) with different carbon chain length amino groups were successfully synthesized. The graphene oxides (GO) reduction as well as amino grafting were achieved simultaneously in one step via a facile solvothermal synthetic strategy. The obtained materials were characterized by X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectrometry and X-ray photoelectron spectroscopy to confirm the modification of GO with different amino groups. The adsorption performance of catechins and caffeine from tea acetonitrile extracts on different amine functional rGO samples were evaluated. It was found that tributylamine-functional rGO (tri-BuA-rGO) exhibited the highest adsorption ability for catechins and caffeine compared to GO and other amino group functional rGO samples. It was worth to note that the adsorption capacity of catechins on tri-BuA-rGO was 11 times higher than that of GO (203.7mgg^-1 vs 18.7mgg^-1). Electrostatic interaction, π-π interaction and surface hydrophilic-hydrophobic properties of tri-BuA-rGO played important roles in the adsorption of catechins as well as caffeine. The gravimetric analysis confirmed that the tri-BuA-rGO achieved the highest efficient cleanup preformance compared with traditional dispersive solid phase extraction (dSPE) adsorbents like primary-secondary amine (PSA), graphitized carbon black (GCB) or C18. A multi-pesticides analysis method based on tri-BuA-rGO is validated on 33 representative pesticides in tea using gas chromatography coupled to tandem mass spectrometry or high-performance liquid chromatography coupled with tandem mass spectrometry. The analysis method gave a high coefficient of determination (r²>0.99) for each pesticide and satisfactory recoveries in a range of 72.1-120.5%. Our study demonstrated that amine functional rGO as a new type of QuEChERS adsorbent is expected to be widely applied for analysis of pesticides at trace levels.

Novel Isocyanate-Modified Carrageenan Polymer Materials: Preparation, Characterization and Application Adsorbent Materials of Pharmaceuticals

The present study focused on the synthesis and application of novel isocyanate-modified carrageenan polymers as sorbent materials for pre-concentration and removal of diclofenac (DCF) and carbamazepine (CBZ) in different aqueous matrices (surface waters and wastewaters). The polymer materials were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermal Gravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). The effects on the adsorption behavior were studied, and the equilibrium data were fitted by the Langmuir and Freundlich models. The maximum adsorption capacity (Q_max) was determined by Langmuir–Freundlich model and was ranged for iota-carrageenan (iCAR) from 7.44 to 8.51 mg/g for CBZ and 23.41 to 35.78 mg/g for DCF and for kappa-carrageenan (kCAR) from 7.07 to 13.78 mg/g for CBZ and 22.66 to 49.29 mg/g for DCF. In the next step, dispersive solid phase extraction (D-SPE) methodology followed by liquid desorption and liquid chromatography mass spectrometry (LC/MS) has been developed and validated. The factors, which affect the performance of D-SPE, were investigated. Then, the optimization of extraction time, sorbent mass and eluent’s volume was carried out using a central composite design (CCD) and response surface methodology (RSM). Under the optimized conditions, good linear relationships have been achieved with the correlation coefficient (R²) varying from 0.9901 to 0.995. The limits of detections (LODs) and limits of quantifications (LOQs) ranged 0.042–0.090 μg/L and 0.137–0.298 μg/L, respectively. The results of the recoveries were 70–108% for both analytes, while the precisions were 2.8–17.5% were obtained, which indicated that the method was suitable for the analysis of both compounds in aqueous matrices.

The choice of ultrasound assisted extraction coupled with spectrophotometric for rapid determination of gallic acid in water samples: Central composite design for optimization of process variables

A sensitive procedure namely ultrasound-assisted (UA) coupled dispersive nano solid-phase microextraction spectrophotometry (DNSPME-UV-Vis) was designed for preconcentration and subsequent determination of gallic acid (GA) from water samples, while the detailed of composition and morphology and also purity and structure of this new sorbent was identified by techniques like field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and Energy-dispersive X-ray spectroscopy (EDX) techniques. Among conventional parameters viz. pH, amount of sorbent, sonication time and volume of elution solvent based on Response Surface Methodology (RSM) and central composite design according to statistics based contour the best operational conditions was set at pH of 2.0; 1.5mg sorbent, 4.0min sonication and 150μL ethanol. Under these pre-qualified conditions the method has linear response over wide concentration range of 15-6000ngmL^-1 with a correlation coefficient of 0.9996. The good figure of merits like acceptable LOD (S/N=3) and LOQ (S/N=10) with numerical value of 2.923 and 9.744ngmL^-1, respectively and relative recovery between 95.54 and 100.02% show the applicability and efficiency of this method for real samples analysis with RSDs below 6.0%. Finally the method with good performance were used for monitoring under study analyte in various real samples like tap, river and mineral waters.

Application of Ni:ZnS nanoparticles loaded on magnetic multi-walled carbon nanotubes as a sorbent for dispersive micro-solid phase extraction of phenobarbital and phenytoin prior to HPLC analysis: experimental design

Ni:ZnSNPs loaded on magnetic MWCNTs are introduced for dispersive micro-solid phase extraction for the first time.