Development of monolithic sorbent cartridges (m-SPE) for the extraction of non-steroidal anti-inflammatory drugs from surface waters and their determination by HPLC

Effect of crosslinker/porogen ratio on sponge-nested polymer monoliths for solid-phase extraction

Polymer monoliths can be polymerised within different molds, but limited options are available for the preparation of free-standing polymer monoliths for analytical sample preparation, and in particular, solid-phase extraction (SPE). Commercial melamine-formaldehyde sponges can be used as supports for the preparation of polymer monoliths, due its flexibility, giving various shapes to monoliths. Herein, the crosslinker/porogen ratio of highly porous sponge-nested divinylbenzene (DVB) polymer monoliths has been evaluated. Monoliths prepared using different crosslinker/porogen ratios were applied to the extraction of bisphenol F, bisphenol A, bisphenol AF, and bisphenol B. Monoliths containing 50 wt % DVB and 50 wt % porogens presented the highest recovery of bisphenols. Under the optimised conditions, the developed method showed a linear range between 2.5 µg L-1 and 150 µg L-1 for BPA and BPAF, and between 5 µg L-1 and 150 µg L-1 for BPB and BPF. The limits of detection (LOD, S/N = 3) and limits of quantification (LOQ, S/N = 10) ranged from 0.36 µg L-1 to 1.09 µg L-1, and from 1.20 µg L-1 to 3.65 µg L-1, respectively. The recoveries for spiked bisphenols (10 µg L-1) in tap water and water contained in a polycarbonate containers were between 82 % and 114 %.

Modification of cellulose substrate by in situ synthesis of metal-organic framework-5 for thin film microextraction of some non-steroidal anti-inflammatory drugs and their measurement by high-performance liquid chromatography-ultraviolet detector

This work, reports the successful preparation a thin film by a simple and inexpensive process for quantification of a model analytes in the urine sample using HPLC-UV. To this end, cellulose paper was employed as a substrate for the in-situ synthesis of MOF-5, to increase the resistance of the prepared film. The prepared film can be reused 26 times with no reduction in its performance. The thin film prepared by MOF-5 modified cellulose substrate was utilized in thin film microextraction (TFME) method for the extraction and preconcentration of naproxen, aspirin, tolmetin, and celecoxib. Under optimal conditions, the linear dynamic range of the target analytes was 2-500 µg L-1 with correlation coefficients (R2) ranging from 0.9961 to 0.9990. Also, the limits of detection (LODs), the limits of quantification (LOQs) and relative standard deviation (RSD%) of the proposed method for selected analytes ranged between 0.57 and 0.77 µg L-1, 1.7 to 2.3 and 3.5 % to 6.2 %, respectively. Moreover, relative recoveries varied from of 94 % to 108 %, indicating the absence of matrices effect in the proposed method. Eventually, the TFME was successfully used for the extraction of selected analytes from urine samples.

Evaluation of organo-vermiculites as sorbent phases for solid-phase extraction of ibuprofen from water

The study of ibuprofen (IBU) preconcentration was carried out making use of a homemade column for solid-phase extraction (SPE), using vermiculite (VT) or organo-vermiculites (OVTs) as sorbent phases. Aqueous samples (50.0 mL) percolated the column and IBU was sorbed onto the VT or OVT and then desorbed using acetonitrile. Employing this SPE system and OVT, calibration curves were generated for IBU, by spectrophotometric quantification using the α-naphthylamine method. R2 values higher than 0.9950 and LOD between 12 and 18 μg L-1 were observed, for real enrichment factors of 21 and 31, by using OVTs. The analytical protocol was applied to three water samples, which were spiked with IBU solutions to evaluate the precision and accuracy of the method. Recoveries between 77 and 110% at three different IBU concentrations and RSD lower than 18% were observed, even by using the spectrophotometric method. The protocol developed in this study demonstrated that the OVT was appropriate to work as a preconcentration phase for IBU determination in water samples.

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.

Magnetic Solid-Phase Extraction Based on Magnetite-Multiwalled Carbon Nanotubes of Non-Steroidal Anti-Inflammatories from Water Followed by LC-ESI-MS/MS

An analytical method based on liquid chromatography-electrospray ionization-tandem mass spectrometry detection (LC-ESI-MS/MS) has been developed for the determination of pharmaceutical compounds in water samples. Five non-steroidal anti-inflammatory drugs (NSAIDs) namely Naproxen, Ketoprofen, Piroxicam, Diflunisal and Celecoxib were investigated. Magnetic solid phase extraction (MSPE) was used for sample pre concentration of water samples and magnetic carbon nanotubes (Fe3O4-MWCNTs) were considered as solid phase extraction sorbent. Important parameters influencing the extraction efficiency such as nature and volume of eluent, sample pH and adsorbent mass were optimized. The developed MSPE method involved 75 mg of Fe3O4-MWCNTs sorbent, 5 mL of water sample at pH = 4 and 5 mL of 10% ammonia in methanol in the elution step. Under the optimized extraction conditions, linearity, detection and quantification limits and reproducibility were evaluated. The proposed method was successfully applied to the analysis of NSAIDs in surface waters, and mean recoveries of all the NSAIDs were above 90% with relative standard deviations < 17%. The detection and quantification limits were comprised between 0.05-3.6 ng.mL-1 and 0.2-11.9 ng.mL-1, respectively.

Determination of polycyclic aromatic hydrocarbons in surface waters by high performance liquid chromatography previous to preconcentration through solid-phase extraction by using polymeric monoliths

A simple, sensitive and reproducible solid-phase extraction method using plastic cartridges containing a monolithic sorbent (m-SPE), coupled to reverse phase liquid chromatography analysis, aiming to determine fifteen polycyclic aromatic hydrocarbons in surface water samples, was developed. The sorbent was easily prepared through a thermal polymerization reaction by using a mixture of n-butyl methacrylate as non-polar monomer and ethylene glycol dimethacrylate as crosslinker contained in a typical Polypropylene syringe cartridge. The effect of different parameters (type of hydrophobic monomer, elution solvent, sample volume, sorbent amount and sorbent load capacity) on the extraction efficiency was optimized. The optimal conditions were achieved by using n-butyl methacrylate as monomer, tetrahydrofurane (THF) as solvent for sorbent cleaning, THF:acetone (1:1) as elution solvent, 25.00 mL of sample volume, 600 µL of the polymerization mixture and 60 µg L^-1 as sample loading capacity. Finally, the sorbent charge capacity, the reusability of the cartridges and the extraction efficiency of the m-SPE monolith, as compared with a typical C8 cartridge, were evaluated. Under the optimized experimental conditions, enrichment factors were between 76 and 103, relative recovery factors from 78 to 103%, accuracy values in the range of 58 to 98%, and inter-batch reproducibility values from between 2 and 10%, were obtained. The limits of detection and quantification were obtained by two different procedures: the signal to noise (S/N) ratios (3 and 10, respectively) and the IUPAC convention. The lowest LOD and LOQ values, obtained with the S/N ratios, were between 0.02 and 1.00 µg L^-1, respectively whereas with the IUPAC convention the values were between 0.07 and 5 µg L^-1. Using this procedure, several PAHs could be detected in the surface water sample taken from a river stream located in La Plata city (Buenos Aires Province, Argentina).

Extraction and determination of tussilagone from Farfarae Flos with online solid-phase extraction-high-performance liquid chromatography using a homemade monolithic cartridge doped with porous organic cage material

A solid-phase extraction cartridge was fabricated using diallyl isophthalate as the monomer with the addition of porous organic cage material via in situ free-radical polymerization in a stainless-steel column. The resulting monolithic adsorbent exhibited a relatively uniform porous structure, a high specific surface area of 113.98 m² /g, and multiple functional chemical groups according to the characterization results. An online solid-phase extraction-high-performance liquid chromatography procedure was fabricated to extract and determine tussilagone from Farfarae Flos. The results show that the complex sample matrices can be removed in the solid-phase extraction procedure. Simultaneously, tussilagone can remain, which can be subsequently switched to an octadecylsilane bonded analytical column. The methodological validation showed that the correlation coefficient was 0.9999 with a linear range of 0.6-200.0 µg/mL, the limit of detection was 0.2 µg/mL, the limit of quantification was 0.6 µg/mL, accuracy was 100.3-100.6%, and relative standard deviation of precision was ≤1.9%. The present monolithic cartridge exhibits good reusability of not more than 100 times. The real sample of Farfarae Flos was determined with a tussilagone content of 0.74 mg/g.

Degradation, solubility and chromatographic studies of Ibuprofen under high temperature water conditions

Ibuprofen (IBP) is an emerging environmental contaminant having low aqueous solubility which negatively affects the application of advanced oxidation and adsorption processes. It was determined that as the temperature increased to 473 K, the mole fraction solubility increased considerably from 0.02 × 10^-3 to 212.88 × 10^-3 (10600-fold). Calculation of the thermodynamic properties indicated an endothermic process, Δ_solH > 0, with relatively high Δ_solS values. Spectroscopic, thermal and chromatographic analyses established the IBP stability at subcritical conditions. In the second part of the study, the degradation of IBP in H₂O₂-modified subcritical was studied and the effect of each process variable was investigated. The optimum degradation of 88% was reached at an IBP concentration of 15 mg L^-1, temperature of 250 °C, 105 min treatment time and 250 mM H₂O₂. The process was optimized by response surface methodology and a mathematical model was proposed and validated. Temperature was determined as the most influential parameter, followed by H₂O₂ concentration. At temperatures higher than 230 °C, a small but noticeable reduction in degradation % suggested that the OH· radicals are consumed at a higher rate than they are produced, through side reactions with other radicals and/or IBP by-products. Finally, potential by-products were determined by gas chromatographic-mass spectrometric analysis and potential by-products were proposed.

Exploration of a Molecularly Imprinted Polymer (MIPs) as an Adsorbent for the Enrichment of Trenbolone in Water

The presence of endocrine disruptors in surface waters can have negative implications on wildlife and humans both directly and indirectly. A molecularly imprinted polymer (MIP) was explored for its potential to enhance the UV-Vis determination of trenbolone in water using solid-phase extraction (SPE). The synthesized MIP was studied using Fourier transform infrared spectra (FTIR) and scanning electron microscopy (SEM). Using the MIP resulted in a preconcentration and enrichment factor of 14 and 8, respectively. Trenbolone binding on the MIP was shown to follow a Langmuir adsorption and had a maximum adsorption capacity of 27.5 mg g−1. Interference studies showed that the MIP selectivity was not compromised by interferences in the sample. The MIP could be recycled three times before significant loss in analyte recovery.