Dispersive liquid–liquid microextraction combined with ultra-high performance liquid chromatography for the simultaneous determination of 25 sulfonamide and quinolone antibiotics in water samples

Development of a new synchronous fluorescence spectrometry combined with Al3+ sensitized for simultaneous and rapid determination of trace flumequine, ciprofloxacin and doxycycline hydrochloride residues in wastewater

Antibiotics are a new type of environmental pollutants. Due to its wide application in many fields, antibiotic residues are ubiquitous in the wastewater environments. Given their potential threat on water ecosystem functioning and public health, the detection of antibiotic residues in wastewater environments has become very necessary. Based on the complexation of Al3+ with flumequine (FLU), ciprofloxacin (CIP) and doxycycline hydrochloride (DOX), their molecular conjugated area were increased and fluorescence intensity were enhanced, combined with synchronous fluorescence spectrometry (SFS) had good selectivity and high sensitivity, a novel method of Al3+ sensitized synchronous fluorescence spectrometry for the determination of FLU, CIP and DOX residues in wastewater was established. When the wavelength difference (Δλ) was selected 115.0 nm, synchronous fluorescence spectra of the three antibiotics could be well separated and the interference of wastewater matrix were eliminated primely. The new SFS made good use of spectral separation instead of conventional chemical separation, and the actual wastewater sample could be directly determined after simple filtration. The experiment results showed that the concentrations of FLU, CIP and DOX in the range of 0.5000-800.0 ng·mL-1, 0.5000-640.0 ng·mL-1 and 10.00-3500 ng·mL-1 had a good linear relationship with fluorescence intensity. The detection limits of three antibiotics were 0.02054 ng·mL-1, 0.03956 ng·mL-1 and 0.8524 ng·mL-1, respectively. Recovery rates of three antibiotics in wastewater samples were 90.72%-98.23%, 88.68%-95.08% and 85.94%-96.70%. The new SFS established in this experiment had the advantages of simple, rapid, sensitive, accurate and good selectivity. Simultaneous and rapid detection of FLU, CIP and DOX residues in wastewater was successfully realized. It had good application prospects in real-time water quality monitoring.

Determination of Multiclass Antibiotics in Fish Muscle Using a QuEChERS-UHPLC-MS/MS Method

The surging global demand for fish has increased aquaculture practices, where antibiotics have become indispensable to prevent diseases. However, the passive incorporation of these compounds into the diet may have adverse effects on human health. In this work, the QuEChERS method combined with ultra-high-performance liquid chromatography tandem mass spectrometry was applied for the determination of 10 multiclass antibiotics (5 quinolones, 2 sulfonamides, 2 diaminopyrimidines, and 1 macrolide) in muscle tissue of farmed fish (European sea bass and gilt-head sea bream). The applied method demonstrated acceptable recovery values, mostly between 70 and 120%, with limits of quantification of the method meeting the established EU maximum residue limits. The analysis of twenty fish samples in duplicate revealed that most antibiotics were not present, with the only exception of oxolinic acid and tilmicosin in European sea bass, which were below the limit of quantification of the method.

Three robust Cd(II) coordination polymers as bifunctional luminescent probes for efficient detection of pefloxacin and Cr2O72- in water

The accurate and rapid detection of antibiotics and heavy-metal-based toxic oxo-anions in water media employing coordination polymers (CPs) as luminescent probes has attracted a lot of attention. Three new Cd(II)-based ternary CPs derived from first-presented L ligands, including [Cd(DCTP)(L)(OH)]n (1), [Cd(TBTA)(L)(OH)]n (2), and [Cd(NPHT)(L)(H2O)]n (3) (L = 2-((1H-imidazol-1-yl)methyl)-5,6-dimethyl-1H-benzo[d]imidazole, H2DCTP = 2,5-dichloroterephthalic acid, H2TBTA = tetrabromoterephthalic acid and H2NPHT = 3-nitrophthalic acid), were successfully assembled and characterized. 1 and 2 show 2D hcb layers, which can be further extended into a 3D supramolecular framework via classic hydrogen bonding interactions. 3 features a 1D double chain that ultimately spreads into a 2D network through weak hydrogen bonding interactions. With the advantages of high stability and excellent luminescent properties, the three CPs display high sensitivity, selectivity, and good anti-interference for the sensing of pefloxacin (PEF) and Cr2O72- ions (LOD values toward PEF: 3.82 × 10-7 mol L-1 for 1, 4.06 × 10-7 mol L-1 for 2, and 1.36 × 10-8 mol L-1 for 3, and toward Cr2O72- ions: 5.97 × 10-7 mol L-1 for 1, 5.87 × 10-7 mol L-1 for 2, and 8.21 × 10-8 mol L-1 for 3). These CPs are the first examples of bifunctional luminescent sensors to detect PEF and Cr2O72- in aqueous solutions. The luminescence quenching mechanisms are explored in detail.

An Automated Solid-Phase Extraction-UPLC-MS/MS Method for Simultaneous Determination of Sulfonamide Antimicrobials in Environmental Water

The large-scale use of sulfonamide antimicrobials in human and veterinary medicine has seriously endangered the ecological environment and human health. The objective of this study was to develop and validate a simple and robust method for the simultaneous determination of seventeen sulfonamides in water using ultra-high performance liquid chromatography-tandem mass spectrometry coupled with fully automated solid-phase extraction. Seventeen isotope-labeled internal standards for sulfonamides were used to correct matrix effects. Several parameters affecting extraction efficiency were systematically optimized, and the enrichment factors were up to 982-1033 and only requiring about 60 min per six samples. Under the optimized conditions, this method manifested good linearity (0.05-100 μg/L), high sensitivity (detection limits: 0.01-0.05 ng/L), and satisfactory recoveries (79-118%) with acceptable relative standard deviations (0.3-14.5%, n = 5). The developed method can be successfully utilized for the determination of 17 sulfonamides in pure water, tap water, river water, and seawater. In total, six and seven sulfonamides were detected in river water and seawater, respectively, with a total concentration of 8.157-29.676 ng/L and 1.683-36.955 ng/L, respectively, and sulfamethoxazole was the predominant congener.

Poly-(MMA-IL) filter paper: A new class of paper-based analytical device for thin-film microextraction of multi-class antibiotics in environmental water samples using LC-MS/MS analysis

A paper-based polymeric ionic liquid (p-Poly-(MMA-IL)) was successfully developed by grafting the polymeric ionic liquid on the surface of commercial filter paper (FP) by using the dipping method, presenting a new cost-effective film. The newly developed p-Poly-(MMA-IL) FP was then applied as a paper-based thin-film microextraction (p-TFME) analytical device to extract 14 compounds as representative of five groups of antibiotic drugs, which were sulfonamides, tetracyclines, fluoroquinolones, penicillin and macrolides in environmental water samples. Besides, p-Poly-(MMA-IL) FP, p-Poly-(MMA) FP, and unmodified filter paper were successfully characterised by FTIR, NMR, FESEM, TGA, and XRD techniques. They underwent significant parameters optimisation, which affected the extraction efficiency. Under optimal conditions, the proposed (p-Poly-(MMA-IL) FP-TFME) device method was evaluated and applied to analyse multi-class antibiotic drugs in environmental water samples by using a liquid chromatography-mass spectrometry (LC-MS). The validation method showed that a good linearity (0.1 μg L^-1 - 500 μg L^-1) was noted (R² > 0.993, n = 3). Detection and quantification limits were within 0.05 μg L^-1 - 4.52 μg L^-1 and 0.15 μg L^-1 - 13.6 μg L^-1, respectively. The relative standard deviation (RSD) values ranged at 1.4%-12.2% (intra-day, n = 15) and 4.4%-11.0% (inter-day, n = 10). The extraction recoveries of environmental water samples ranged from 79.1% to 126.8%, with an RSD of less than 15.4% (n = 3). The newly developed paper-based polymeric ionic liquid (p-Poly-(MMA-IL) FP) for analysis of multi-class antibiotic drugs under the p-TFME analytical device procedure was successfully achieved with limited sample volume and organic solvent, fast extraction, and feasible in daily analysis. The detection concentration and relative RSD of multi-class antibiotics determined in various environmental water samples by the proposed method (n = 5) were within 0.44 μg L^-1 - 54.41 μg L^-1 and 0.69%-15.56%, respectively. These results signified the potential of the p-Poly-(MMA-IL) FP-TFME device as an efficient, sensitive and environmentally friendly approach for analysing antibiotics.

Combining environmental, health, and safety features with a conductor like Screening Model for selecting green solvents for antibiotic analyses

Extraction and chromatographic techniques for analyzing pharmaceutically active compounds necessitate large quantities of organic solvents, resulting in a high volume of hazardous waste. The concept of green solvents focuses on protecting the environment by reducing or even eliminating the use of toxic solvents. The main objective of this critical review article is to build a framework for choosing green solvents for antibiotic analyses. The article briefly discusses the chemical properties of ciprofloxacin, sulfamethoxazole, tetracycline, and trimethoprim, and the current state of methodologies for their analyses in water and wastewater. It evaluates the greenness of solvents used for antibiotic analyses and includes insights on the comparison between conventional and green solvents for the analyses. An economic and environmental health and safety analysis combined with a Conductor-like Screening Model for Real Solvent (COSMO-RS) molecular simulation technique for predicting extraction efficiency was used in the evaluation. Methyl acetate and propylene carbonate tied for the greenest solvents from an environmental and economic perspective, whereas the COSMO-RS approach suggests dimethyl sulfoxide (DMSO) as the most suitable candidate. Although DMSO ranked third environmentally and economically, after methyl acetate and propylene carbonate, it would be an ideal replacement of hazardous solvents if it could be manufactured at a lower cost. DMSO showed the highest extraction capacity, as it can interact with antibiotics through hydrophobic interaction and hydrogen bonding. This article can be used as a green solvent selection guide for developing sustainable processes for antibiotic analyses.

Complementarity of two approaches based on the use of high-resolution mass spectrometry for the determination of multi-class antibiotics in water. Photodegradation studies and non-target screenings

The development of analytical methodologies to monitor different antibiotic families in water and the implementation of alternatives for their efficient elimination are a great challenge. The aim of this research was to develop a method based on solid-phase extraction followed by ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry to analyse multi-class antibiotics, including macrolides, cephalosporins, fluoroquinolones, sulfonamides and diaminopyrimidines, in waters. Several parameters affecting the extraction such as the sample pH, type of sorbent and cartridge, elution volume and breakthrough volume were optimized. The method was validated in real samples, and matrix effect was assessed, demonstrating that the use of isotopically labelled surrogate compounds was mandatory to avoid standard addition calibration for each individual samples. Urban and hospital wastewater samples, as well as natural waters, were analysed, confirming the presence of 12 of the 14 target compounds at concentrations up to 3.5 µg L-1. Non-target analysis based on data-independent workflow was also performed, enabling the identification of 94 pollutants. Preliminary photodegradation experiments were also assessed, revealing the total removal of many target compounds after the first 5-10 min of UVC irradiation. In addition, 20 by-products formed after photolysis could be identified using a non-target approach.

Microextraction procedures for preconcentration of Fe (III) in water and food samples prior to colorimetric detection: a comparative study

Two extraction procedures, namely dispersive liquid-liquid microextraction (DLLME) and dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFOD), have been compared for the spectrophotometric determination of Fe (III). In both procedures, Fe (III) was extracted after complexation with gallic acid in the presence of cetyltrimethylammonium bromide (CTAB). Tetrachloroethylene and 1-undecanol were used as extraction solvents in DLLME and DLLME-SFOD, respectively, while acetone was used as dispersing solvents. The effects of various experimental parameters (solution pH, the concentration of ligand and CTAB, as well as nature and amount of extraction and disperser solvents) on the extraction efficiency were investigated. Under optimum conditions, the calibration graphs were linear in the range of 50.0–650.0 and 8.0–800.0 μg L−1 and the detection limits were 15.0 and 5.0 μg L−1 for DLLME and DLLME-SFOD, respectively. The presence of NaCl, up to 1.0% (w/v) did not impact the extraction procedures. The analyte was good tolerated in the presence of most concomitant ions. The procedures were applied for the determination of Fe (III) in standard reference materials and real samples with good recoveries (95.5–99.0%) for DLLME-SFOD while poor recoveries (68.0–82.5%) were obtained when DLLME was applied. The analytical figures of the procedures were comparable with those listed in the literature and it could be concluded that DLLME-SFOD may be considered one of the best tools used for preconcentration of Fe (III), owing to its simplicity, time-saving and the possibility of using in conventional analytical laboratories.

Graphical abstract

Determination of quinolone antibiotics in environmental water using automatic solid-phase extraction and isotope dilution ultra-performance liquid chromatography tandem mass spectrometry

The widespread use of quinolones in humans and animals has become a major threat to public health. In this study, a simple, rapid, sensitive, and high throughput method based on automatic solid-phase extraction and isotope dilution ultra-performance liquid chromatography tandem mass spectrometry was described for the determination of trace quinolones in environmental water. The proposed automated solid-phase extraction method was initially optimized, and the optimum experimental conditions found were 1 L water sample with 0.5 g/L Na₂EDTA (pH 3) extracted and enriched by CNW Poly-Sery HLB cartridge at a flow rate of 50 mL/min and eluted by 8 mL of methanol. The linearity of the method ranged from 0.05 to 100 μg/L for 15 quinolones, with correlation coefficients ranging from 0.9993 to 0.9999. The limits of detection were in the low ng/L level, ranging from 0.005 to 0.051 ng/L. Finally, the optimized method was applied for determining trace levels of 15 quinolones in Wahaha pure water, tap water, river water, and seawater samples with good recoveries of 93 %-119 % and satisfactory relative standard deviations of 0.1 %-13.9 %. Fourteen quinolones were detected, and ofloxacin was the predominant congener in river water and seawater.

QuEChERS-based analysis and ecotoxicological risk of select antibiotics in dumpsite leachates, hospital wastewater and effluent receiving water in Ibadan, Nigeria

There is currently a dearth of information on the determination, occurrence and ecotoxicological risk of antibiotics in dumpsite leachates and hospital wastewater in Africa. A quick, easy, cheap, effective, rugged and safe (QuEChERS) protocol which combines extraction and clean-up in one step was optimized for the determination of antibiotics sulfadoxine, sulfamethazine and trimethoprim in dumpsite leachates and hospital wastewater. The occurrence and ecotoxicological risk of target antibiotics were investigated in wastewater from two hospitals, effluent receiving water and leachates from three dumpsites in Ibadan, Nigeria. Recoveries in hospital wastewater ranged from 53 to 116% while recoveries ranged from 50 to 89% in leachates. Method limits of quantification ranged from 0.7 to 12.1 µg L^-1 in hospital wastewater and from 6.2 to 38.8 µg L^-1 in leachates. Intra-day precisions (% RSD) were ≤ 21%. High concentrations of target antibiotics were measured: up to 475 µg L^-1 for sulfamethazine in leachates, 118 µg L^-1 for trimethoprim in hospital wastewater and 117 µg L^-1 for sulfadoxine in effluent receiving water. Sulfadoxine presented high risk to algae, daphnid and fish in hospital wastewater, effluent receiving water and leachates. This work highlights the need for adequate and sound management of wastes containing pharmaceuticals in Nigeria.

An effervescence-assisted dispersive liquid-liquid microextraction based on three-component deep eutectic solvent for the determination of fluoroquinolones in foods

An effervescence-assisted dispersive liquid-liquid microextraction approach using three-component deep eutectic solvent based on short-chain and medium-chain carboxylic acids and terpenoid was developed for the first time. The microextraction procedure was applied to the determination of fluoroquinolone antibiotics in foods (milk and shrimp samples) by high-performance liquid chromatography with fluorometric detection. In this microextraction procedure three-component deep eutectic solvent acted as a proton donor agent and an extractant. The carbon dioxide bubbles caused by the fast reaction between precursor of deep eutectic solvent (short-chain carboxylic acid) and effervescent agent (sodium carbonate) promoted the dispersion of the extractant in an aqueous sample phase. Various carboxylic acids were studied as hydrogen bond donors for the formation of deep eutectic solvents and proton donor agents for the generation of CO₂ bubbles. Two natural terpenoids (menthol and thymol) were studied as the hydrogen bond acceptors for the formation of three-component solvent. The extraction system based on heptanoic acid and thymol (1:2, mol/mol) containing formic acid (proton donor for generating CO₂ bubbles) provided maximum extraction recovery (86-99%) and a higher extraction efficiency of analytes compared to their extraction into individual hydrophobic precursors of the system. The LODs, calculated from the blank tests based on 3σ, were varied from 0.03 to 0.06 μg L^-1 and from 0.3 to 0.6 μg kg^-1 for fluoroquinolone antibiotics in milk and shrimp samples, respectively. The proposed approach provided effective dispersion of extractant speeding up the extraction process and fast separation of phases without any external energy assistance.

A magnetic ionic liquid based vortex-assisted dispersive liquid-liquid microextraction coupled with back-extraction for the enrichment of fluoroquinolone antibiotics

In the present work, a magnetic ionic liquid (MIL) ([Co(DMBG)₂][Co(hfaca)₃]) was designed and synthesized with both the cation and anion respectively containing a paramagnetic component. With the prepared MIL as the extraction solvent, a vortex-assisted dispersive liquid-liquid microextraction (VA-DLLME) method was developed and combined with back-extraction for the enrichment of five fluoroquinolone antibiotics (FQs). The MIL can be easily collected and separated from the aqueous phase under an external magnetic field due to the strong magnetic susceptibility and red color. Some experimental factors affecting the extraction efficiency were investigated, and the optimum extraction efficiency was obtained in a basic solution (pH=9) for the extraction process and with 2% (v/v) formic acid as the back-extraction solvent. Under the optimized extraction and back-extraction conditions, the proposed method was validated and exhibited good linearity with coefficients of determination (R²) above 0.9956 in the range of 2.5-800 ng·mL^-1 and 5.0-800 ng·mL^-1, low limits of detection (LODs) within 0.75-1.5 ng·mL^-1 and satisfactory intra-day and inter-day precisions with relative standard deviations (RSDs) respectively less than 10.6% and 8.6%. Finally, the method was applied for the determination of five FQs in four samples of tap water, milk, honey and chicken, and good precision with RSDs of 0.5-9.5% and acceptable recoveries (73.8-114.3%) were obtained.

Lab-In-Syringe automation of deep eutectic solvent-based direct immersion single drop microextraction coupled online to high-performance liquid chromatography for the determination of fluoroquinolones

Lab-In-Syringe direct immersion single drop microextraction is proposed as an automated sample pretreatment methodology and coupled online to HPLC with fluorescence detection for the determination of fluoroquinolones in environmental waters. For the first time, a drop of a natural deep eutectic solvent (NADES), synthesized from hexanoic acid and thymol, has been used as an extractant in automated single-drop microextraction. The extraction procedure was carried out within the 5 mL void of an automatic syringe pump. A 9-position head valve served the aspiration of all required solutions, air, waste disposal, and hyphenation with the HPLC instrument. Sample mixing during extraction was done by a magnetic stirring bar placed inside the syringe. Only 60 μL of NADES were required omitting toxic classical solvents and improving the greenness of the proposed methodology. By direct injection, linear working ranges between 0.1 and 5 μg L^-1 were achieved for all fluoroquinolones. The limit of quantification values and enrichment factors ranged from 20 ng L^-1 to 30 ng L^-1 and 35 to 45, respectively. Accuracies obtained from the analysis of spiked surface water and wastewater treatment plant effluent analysis at two concentration levels (0.5 and 4 μg L^-1) ranged from 84.6% to 119.7%, with RSD values typically <3%.

Simultaneous Determination of Sulfonamides Antibiotics in Environmental Water and Seafood Samples Using Ultrasonic-Assisted Dispersive Liquid-Liquid Microextraction Coupled with High Performance Liquid Chromatography

The residues and abuse of antibiotics have seriously endangered ecological balance and human health; meanwhile, antibiotics determination is very difficult because of their low levels and multiple categories in complicated matrices. Appropriate sample pretreatment is usually imperative to enrich (ultra)trace antibiotics and eliminate matrix interference prior to chromatographic analysis. Dispersive liquid-liquid microextraction (DLLME) has become an ideal pretreatment technique owing to its simplicity, effectiveness, low-consumption, etc. In this work, an ultrasonic-assisted DLLME (UA-DLLME) was developed for the simultaneous extraction of seven sulfonamides (SAs) antibiotics in environmental water and seafood samples coupled with HPLC-DAD determination. Several parameters affecting UA-DLLME efficiency were systematically optimized, and consequently the SAs were separated and detected within 14.5 min. The obtained limits of detection (LODs) and limits of quantification (LOQs) ranged from 0.7-7.8 μg/L and 2.4-26.0 μg/L for three water samples (seawater, aquaculture wastewater and lake water) and two seafood samples (pomfrets and shrimps). High recoveries (80.0-116.0%) with low relative standard deviations (0.1-8.1%) were achieved for all the tested samples at three spiked levels. Notably, sulfadimethoxine was found at 24.49 μg/L in one seawater sample. The facile, robust and benign DLLME-HPLC method demonstrated promising perspectives for multiresidue analysis of antibiotics.

Multi-templates surface molecularly imprinted polymer for simultaneous and rapid determination of sulfonamides and quinolones in water: effect of carbon-carbon double bond

In this work, the effect of a carrier modified with a carbon-carbon double bond (C=C) on preparing multi-templates surface molecularly imprinted polymer MIP (C=C@MIP) for simultaneous detection of sulfonamides and quinolones was investigated. The results showed that the adsorption capacities of the C=C@MIP were obviously higher than those of MIP, which is the carrier without modified C=C, suggesting that C=C played a key role in preparing MIP with higher adsorption capacities. Then, C=C@MIP was used as adsorbents for solid-phase extraction (SPE) and coupled with high-performance liquid chromatography (HPLC) for the simultaneous determination of sulfonamides and quinolones in water. The method showed excellent applicability, with the adsorption capacities of 19.92, 16.38, 12.92, 18.37, 14.49, 12.01, 16.98, 23.33, and 14.29 mg/g for SDZ, STZ, SMZ, SMX, SDM, ENRO, OFL, LOME, and GATI, respectively. The spiked recoveries and relative standard deviations (RSDs) of sulfonamides and quinolones using C=C@MIP were 81.59-100.7 % and 3.75-7.37 %, respectively. The limits of detection (LODs) for SDZ, STZ, SMZ, SMX, SDM, ENRO, OFL, LOME, and GATI were 0.013, 0.012, 0.012, 0.013, 0.014, 0.012, 0.013, 0.015, and 0.015 μg/L, respectively.

Hydrophobic magnetic nanoparticle assisted catanionic surfactant supramolecular solvent microextraction of multiresidue antibiotics in water samples

A novel extraction technique i.e. hydrophobic magnetic nanoparticle (MNP)-assisted in situ supramolecular solvent (SUPRAS) microextraction was proposed, and it was applied for the analysis of sulfonamides (SAs) and fluoroquinolones (FQs) in aqueous samples, coupled with high performance liquid chromatography-UV detection (HPLC-UV). In this extraction method, hexafluoroisopropanol-mediated salt-free catanionic surfactant based SUPRAS in situ microextraction was initially carried out; then, the SUPRAS was quickly adsorbed by the hydrophobic magnetic nanoparticles and gathered by an external magnetic field. This can greatly shorten the separation time and overcome the dependence on centrifugation, and also perform a secondary extraction of free analytes (not extracted by SUPRAS) from water samples. The magnetic separation ability of different hydrophobic MNPs was evaluated by adsorbing supramolecular aggregates from the water sample. The effective parameters affecting the extraction efficiency of the analytes were investigated and optimized using the one variable at a time method. About 3 min was required to realize the extraction of analytes with an enrichment factor (EF) of 12-53 for SAs and 79-118 for FQs. Compared with the centrifugation-assisted SUPRAS microextraction, the hydrophobic MNP-assisted SUPRAS microextraction obtained much better extraction and preconcentration efficiency. The proposed novel extraction method with HPLC-UV provided LODs of 0.21-0.76 ng mL-1 for SAs and 0.10-0.18 ng mL-1 for FQs. Good linearity was obtained with correlation coefficients ranging from 0.9962 to 0.9999. The intra- and inter-day recoveries of the target antibiotics were in the range of 92.0-111.3% with RSD% below 10.4%. The method was successfully applied to determine SAs and FQs in real water samples, such as lake water, river water, reservoir water, and wastewater.

A selective and efficient microfluidic method-based liquid phase microextraction for the determination of sulfonamides in urine samples

Liquid phase microextraction (LPME) into a microfluidic has undergone great advances focused on downscaled and miniaturized devices. In this work, a microfluidic device was developed for the extraction of sulfonamides in order to accelerate the mass transfer and passive diffusion of the analytes from the donor phase to the acceptor phase. The subsequent analysis was carried out by high performance liquid chromatography with UV-DAD (HPLC-DAD). Several parameters affecting the extraction efficiency of the method such as the supported liquid membrane, composition of donor and acceptor phase and flow rate were investigated and optimized. Tributyl phosphate was found to be a good supported liquid membrane which confers not only great affinity for analytes but also long-term stability, allowing more than 20 consecutive extractions without carry over effect. Under optimum conditions, extraction efficiencies were over 96 % for all sulfonamides after 10 minutes extraction and only 10 µL of sample was required. Relative standard deviation was between 3-5 % for all compounds. Method detection limits were 45, 57, 54 and 33 ng mL^-1 for sulfadiazine (SDI), sulfamerazine (SMR), sulfamethazine (SMT) and sulfamethoxazole (SMX), respectively. Quantitation limits were 0.15, 0.19, 0.18 and 0.11 µg mL^-1 for SDI, SMR, SMT SMX, respectively. The proposed microfluidic device was successfully applied for the determination of sulfonamides in urine samples with extraction efficiencies within the range of 86-106 %. The proposed method improves the procedures proposed to date for the determination of sulfonamides in terms of efficiency, reduction of the sample volume and extraction time.

QuEChERS Approach for the Analysis of Three Fluoroquinolone Antibiotics in Wastewater: Concentration Profiles and Ecological Risk in Two Nigerian Hospital Wastewater Treatment Plants

Hospital wastewater is regarded as a primary and very important source of antibiotics in the aquatic environment. Studies on the analysis, occurrence, and ecological risk assessment of fluoroquinolone antibiotics in wastewater are still limited in Africa. A quick, easy, cheap, effective, rugged, and safe extraction method was optimized and applied for determination of three fluoroquinolone antibiotics (ciprofloxacin, norfloxacin, and ofloxacin) in wastewater from two Nigerian hospital wastewater treatment plants (WWTPs) and effluent receiving water. Separation, detection, and quantification of target fluoroquinolone antibiotics were performed by high-performance liquid chromatography. Ecological risk of the three fluoroquinolone antibiotics was evaluated for three trophic levels: fish, daphnid, and algae. The method LODs were 4.1 µg L^-1, 7.0 µg L^-1, and 18.5 µg L^-1 for ciprofloxacin, norfloxacin, and ofloxacin, respectively. Satisfactory recoveries and precisions were achieved, in addition to the correlation coefficients of greater than 0.993. Target fluoroquinolones were quantified in influents up to 228 µg L^-1 (UCH influent) for ciprofloxacin, 561 µg L^-1 (Ijaiye influent) for norfloxacin, and 198 µg L^-1 (UCH influent) for ofloxacin. Norfloxacin had the highest concentration (386 µg L^-1) in effluent receiving water. All three fluoroquinolones posed low risk to fish, whereas ciprofloxacin and norfloxacin presented moderate risk to daphnid and algae. To the best of our knowledge, this work presents the first data on the occurrence and risk assessment of the target fluoroquinolones in wastewater from Nigerian hospital WWTPs. The findings revealed the importance of developing local and nationwide surveys of fluoroquinolone antibiotics in the Nigerian aquatic environment.

Collection and Separation of Fleroxacin and Ciprofloxacin in Ultrasound-Assisted Ionic Liquid Salting-Out Microextraction System

An ultrasound-assisted ionic liquid (IL) salting-out microextraction system was developed and applied for the extraction of quinolone antibiotics from urine. A precipitate was formed from the salt and IL, and it acted as the sorbent for the analytes. The precipitate containing the analyte was separated by filtration, redissolved, and the solution then was evaporated. The resulting extract was redissolved for high-performance liquid chromatographic analysis. Several parameters, including type and volume of IL, the type and amount of salts, sample pH, temperature and extraction time were optimized. Under the optimal experimental conditions, the limits of detection for fleroxacin and ciprofloxacin were 3.12 and 4.97 μg L-1, respectively. When the present method was applied to real urine sample analysis, the analyte recoveries ranged from 82.3 to 106.8%. This ultrasound-assisted IL salting-out microextraction system had the characteristics of high recoveries, shorter separation time and easy-to-perform collection procedure, which yielded the method to have potential for wide application.

Ionic Liquid-based Hollow Fiber Liquid–Liquid–Liquid Microextraction Combined with Capillary Electrophoresis for the Determination of Sulfonamides in Aquaculture Waters

Ionic liquid-based hollow-fiber liquid–liquid–liquid microextraction (IL-HF-LLLME) coupled to capillary electrophoresis (CE) has been developed for the determination of six sulfonamides (SAs) in aquaculture waters. A series of extraction parameters was optimized to enhance the extraction efficiency, which included type and pore size of hollow fiber, type and composition of extraction solvent, pH value of donor phase, the concentration of acceptor phase and the mass ratio of donor phase to acceptor phase along with extraction temperature and time. Under optimal conditions, the IL-HF-LLLME-CE method provided a wide liner range for six SAs from 2 to 1,000 μg L−1 (r2 ≥ 0.9995), the limits of the detection from 0.25 to 0.48 and the enrichment factors from 122 to 230, respectively. Relative standard deviations for intra- and interday precision were 1.4–5.3% and 1.8–7.5% (n = 5), respectively. The proposed method was successfully applied for the determination of trace-level SAs in seven real-world aquaculture water samples with good recoveries (80.4–100.7%). Also, sulfamerazine and sulfamethoxazole were detected at the level of 0.52–1.60 μg L−1 in two water samples. Due to its good sensitivity, simple operation, short analysis time and eco-friendliness, the developed method has a great application potential in analysis of trace SA residues in aquaculture waters.

Supramolecular Solvent Based Liquid-Liquid Microextraction for Preconcentration of Selected Fluoroquinolone Antibiotics in Environmental Water Sample Prior to High Performance Liquid Chromatographic Determination

Background and Objective:

A rapid, simple and environmental friendly supramolecular solvent (SUPRAS) based liquid-liquid microextraction method for preconcentration of ciprofloxacin (CIPRO), danofloxacin (DANO) and enrofloxacin (ENRO) from wastewater was developed.

Methods:

This microextraction technique was coupled with high-performance liquid chromatography equipped with a diode array detector (HPLC-PDA) for detection and separation of the antibiotics. The SUPRAS composed of decanoic acid and tricaprylymethylammonium chloride. Optimum conditions for the extraction and preconcentration of all the antibiotics were obtained using surface response methodology (RSM) based on Box-Behnken design.

Results:

Under optimum conditions, the limits of detection (LOD) and limit of quantification (LOQ) ranged from 0.06-0.14 µg L−1 and 0.22-0.47 μg L−1, respectively with the preconcentration factors ranging from 153-241. The linear dynamic ranges were between LOQ and 850 µg L−1 with correlation coefficients ranging from 0.9928 to 0.9999. The intra-day (n = 15) and inter-day (n = 5) precisions (expressed in terms of %RSD) for 50 µg L−1 of CIPRO, DANO and ENRO were in the range of 3.3–4% and 4.1–5.8%, respectively.

Conclusion:

Lastly, the developed method was used for the extraction, preconcentration and quantification of selected CIPRO, DANO and ENRO in influent and effluent wastewater samples.

Recent Trends in Fast Liquid Chromatography for Pharmaceutical Analysis

Background:

Liquid chromatography is the workhorse of analytical laboratories of pharmaceutical companies for analysis of bulk drug materials, intermediates, drug products, impurities and degradation products. This efficient technique is impeded by its long and tedious analysis procedures. Continuous efforts of scientists to reduce the analysis time resulted in the development of three different approaches namely, HTLC, chromatography using monolithic columns and UHPLC.

Methods:

Modern column technology and advances in chromatographic stationary phase including silica-based monolithic columns and reduction in particle and column size (UHPLC) have not only revolutionized the separation power of chromatographic analysis but also have remarkably reduced the analysis time. Automated ultra high-performance chromatographic systems equipped with state-ofthe- art software and detection systems have now spawned a new field of analysis, termed as Fast Liquid Chromatography (FLC). The chromatographic approaches that can be included in FLC are hightemperature liquid chromatography, chromatography using monolithic column, and ultrahigh performance liquid chromatography.

Results:

This review summarizes the progress of FLC in pharmaceutical analysis during the period from year 2008 to 2017 focusing on detecting pharmaceutical drugs in various matrices, characterizing active compounds of natural products, and drug metabolites. High temperature, change in the mobile phase, use of monolithic columns, new non-porous, semi-porous and fully porous reduced particle size of/less than 3μm packed columns technology with high-pressure pumps have been extensively studied and successively applied to real samples. These factors revolutionized the fast high-performance separations.

Conclusion:

Taking into account the recent development in fast liquid chromatography approaches, future trends can be clearly predicated. UHPLC must be the most popular approach followed by the use of monolithic columns. Use of high temperatures during analysis is not a feasible approach especially for pharmaceutical analysis due to thermosensitive nature of analytes.

Screening of pesticides and veterinary drugs in small streams in the European Union by liquid chromatography high resolution mass spectrometry

Water samples from 29 small waterways located in 10 different countries in the European Union were screened for the presence of a large number of pesticides (275) and veterinary drugs (101). Solid phase extraction was combined with liquid chromatography coupled to Orbitrap high resolution tandem mass spectrometry to quantify the levels of pesticides in the samples and to detect the presence of veterinary drugs. All the sampled European rivers and canals included in this investigation were contaminated with mixtures of pesticides and, in most of the cases, with several veterinary drugs at the time of sampling, without a clear national or regional pattern. In total, 103 different pesticides, 24 of them banned in the EU, and 21 veterinary drugs were found in the analysed samples. Herbicides were the main contributor to the total amount of pesticides found in the samples, with terbuthylazine present in all the samples. The maximum individual concentration recorded was of dimethenamid at 59.85 μg L^-1. The maximum combined pesticide concentration was found in a sample from the Wulfdambeek canal, Belgium, with 94.02 μg L^-1 comprised of a mixture of 70 different pesticides. European regulatory standards defining acceptable concentration levels were exceeded for at least one pesticide in 13 of the 29 samples analysed, with the neonicotinoid insecticides imidacloprid and clothianidin most frequently present above such limits. The majority of the veterinary drugs detected were antimicrobials, most being antibiotics. The β-lactam antibiotic dicloxacillin was present in two thirds of the analysed samples. The application of this consistent research approach across Europe allowed the identification of a significant threat to the aquatic environment associated with pesticide contamination, and in some cases veterinary drugs, at the time of sampling in the water bodies tested.

Rapid screening of sulfonamides in dietary supplements based on extracted common ion chromatogram and neutral loss scan by LC-Q/TOF-mass spectrometry

There is an increasing amount of dietary supplements that are adulterated with diuretics and anti-diabetic drugs; this has become a global problem due to the wide distribution of dietary supplements and the serious negative health effects of the adulterants. In this study, a rapid screening method was developed for detection and confirmation of 35 sulfonamides in supplements by ultra-high performance liquid chromatography quadrupole/ time of flight mass spectrometry. For effective extraction of sulfonamides from dietary supplements, four extraction protocols including HLB and WAX solid-phase extraction, Quick Easy Cheap Effective Rugged and Safe method, and pH-controlled liquid–liquid extraction were evaluated, and pH-controlled liquid–liquid extraction method was shown to be the most effective with high recovery efficiency and low matrix effect. Rapid separation of 35 sulfonamides was achieved with the UHPLC C18 column (150 × 2.1 mm, 1.7 um) within 7 min using ammonium acetate aqueous solution (pH 8) and acetonitrile as the mobile phase. From the MS/MS spectra of sulfonamides, common ions (m/z 77.9650 [SO₂N]⁻ and m/z 79.9812 [SO₂NH₂]⁻) and neutral molecule loss fragments (HCl and SO₂) were observed according to their structural characteristics. Extracted common ion chromatograms and neutral loss scan of these characteristic fragments could effectively apply for rapid screening of sulfonamides in various types of supplements. A reduced mass tolerance window of ±5 ppm was useful for detecting targeted and untargeted sulfonamides and could avoid false positive and false negative results. Overall calibration curves within dynamic range for all targets were shown to be linear with a correlation coefficient R² > 0.995 and limits of detection ranged from 0.04 to 11.18 ng/g for all sulfonamides. The established method was successfully applied for screening and confirmation of sulfonamides in various supplements. The developed method will be helpful for the identification of sulfonamide diuretics and anti-diabetics in dietary supplements, promoting public health and consumer safety.

Solvent-terminated dispersive liquid-liquid microextraction: a tutorial

Solvent-terminated dispersive liquid-liquid microextraction (ST-DLLME) is a special mode of DLLME in which a demulsifying solvent is injected into the cloudy mixture of sample/extractant to break the emulsion and induce phase separation. The demulsification process starts by flocculation of the dispersed microdroplets by Ostwald ripening or coalescence to form larger droplets. Then, the extractant either floats or sinks depending on its density as compared with that for the aqueous sample. The demulsifier should have high surface activity and low surface tension in order to be capable of inducing phase separation. The extraction efficiency in ST-DLLME is controlled by the same experimental variables of normal DLLME (n-DLLME) such as the type and volume of the extractant as well as the disperser. Other parameters such as pH and the temperature of the sample, the stirring rate, the time of extraction and the addition of salt are also important to consider. Along with these factors, the demulsifier type and volume and the demulsification time have to be optimized. By using solvents to terminate the dispersion step in DLLME, the centrifugation process is not necessary. This in turn improves precision, increases throughput, decreases the risk of contamination through human intervention and minimizes the overall analysis time. ST-DLLME has been successfully applied for determination of both inorganic and organic analytes including pesticides and pharmaceuticals in water and biological fluids. Demulsification via solvent injection rather than centrifugation saves energy and makes ST-DLLME easier to automate. These characteristics in addition to the low solvent consumption, the reduced organic waste and the possibility of using water in demulsification bestow green features on ST-DLLME. This tutorial discusses the principle, the practical aspects and the different applications of ST-DLLME.

Microwave assisted solid phase extraction for separation preconcentration sulfamethoxazole in wastewater using tyre based activated carbon as solid phase material prior to spectrophotometric determination

This work was chiefly encouraged by the continuous consumption of antibiotics which eventually pose harmful effects on animals and human beings when present in water systems. In this study, the activated carbon (AC) was used as a solid phase material for the removal of sulfamethoxazole (SMX) in wastewater samples. The microwave assisted solid phase extraction (MASPE) as a sample extraction method was employed to better extract SMX in water samples and finally the analysis of SMX was done by the UV-Vis spectrophotometer. The microwave assisted solid phase extraction method was optimized using a two-level fractional factorial design by evaluating parameters such as pH, mass of adsorbent (MA), extraction time (ET), eluent ratio (ER) and microwave power (MP). Under optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) were 0.5μgL^-1 and 1.7μgL^-1, respectively, and intraday and interday precision expressed in terms of relative standard deviation were >6%.The maximum adsorption capacity was 138mgg^-1 for SMX and the adsorbent could be reused eight times. Lastly, the MASPE method was applied for the removal of SMX in wastewater samples collected from a domestic wastewater treatment plant (WWTP) and river water.

Identification of antibiotics in wastewater: current state of extraction protocol and future perspectives

The release and occurrence of antibiotics in the aquatic environment has generated increased attention in the past few decades. The residual antibiotic in wastewater is important in the selection for antimicrobial resistance among microorganisms and the possibility of forming toxic derivatives. This review presents an assessment of the advancement in methods for extraction of antibiotics with solid phase extraction and liquid-liquid extraction methods applied in different aquatic environmental media. These advanced methods do enhance specificity, and also exhibit high accuracy and recovery. The aim of this review is to assess the pros and cons of the methods of extraction towards identification of quinolones and sulphonamides as examples of relevant antibiotics in wastewater. The challenges associated with the improvements are also examined with a view of providing potential perspectives for better extraction and identification protocols in the near future. From the context of this review, magnetic molecular imprinted polymer is superior over the remaining extraction methods (with the availability of commercial templates and monomers), is based on less cumbersome extraction procedures, uses less solvent and has the advantage of its reusable magnetic phase.

Selective determination of sulfonamides from environmental water based on magnetic surface molecularly imprinting technology

In the study, a simple and selective method based on magnetic separation technology is presented for the extraction of sulfonamides (SAs) from environmental water, followed by liquid chromatography-tandem mass spectrometry. In this method, magnetic surface molecularly imprinted polymers (Fe₃O₄@SiO₂@MIPs) with super-paramagnetic property and high selectivity toward SAs were developed as magnetic adsorbents. The Fe₃O₄@SiO₂@MIPs were then applied to the selective extraction of SAs from environmental water. The extraction and enrichment were accomplished simultaneously in a single step by simply stirring the mixture of adsorbents and water samples. The Fe₃O₄@SiO₂@MIPs were characterized by scanning electron microscopy, Fourier-transform infrared spectrometry, and vibrating sample magnetometry. The adsorption thermodynamics and kinetics were employed to study the adsorption mechanism of the Fe₃O₄@SiO₂@MIPs. And the matrix effect of the method was evaluated. Calibration curves obtained by analyzing matrix-matched standards show excellent linear relationship (R = 0.9994-0.9999) in the concentration range of 10-1000 ng L^-1, and the limits of detection are in the range of 1.4-2.8 ng L^-1. The relative standard deviations of intra- and inter-day obtained are in the range of 2.8 to 7.8 and 3.1 to 7.9%, respectively. The proposed method was successfully applied to determine SAs in six environmental water samples, and SAs were detectable in four of them with the concentration from 10.5 to 120.2 ng L^-1.