On-line solid phase extraction using organic–inorganic hybrid monolithic columns for the determination of trace β-lactam antibiotics in milk and water samples

Advances in solid-phase extraction techniques: Role of nanosorbents for the enrichment of antibiotics for analytical quantification

Antibiotics are life-saving medications for treating bacterial infections; however it has been discovered that resistance developed by bacteria against these incredible agents is the primary contributing factor to rising global mortality rates. The fundamental cause of the emergence of antibiotic resistance in bacteria is the presence of antibiotic residues in various environmental matrices. Although antibiotics are present in diluted form in environmental matrices like water, consistent exposure of bacteria to these minute levels is enough for the resistance to develop. So, identifying these tiny concentrations of numerous antibiotics in various and complicated matrices will be a crucial step in controlling their disposal in those matrices. Solid phase extraction, a popular and customizable extraction technology, was developed according to the aspirations of the researchers. It is a unique alternative technique that could be implemented either alone or in combination with other approaches at different stages because of the multitude of sorbent varieties and techniques. Initially, sorbents are utilized for extraction in their natural state. The basic sorbent has been modified over time with nanoparticles and multilayer sorbents, which have indeed helped to accomplish the desired extraction efficiencies. Among the current traditional extraction techniques such as liquid-liquid extraction, protein precipitation, and salting out techniques, solid-phase extractions (SPE) with nanosorbents are most productive because, they can be automated, selective, and can be integrated with other extraction techniques. This review aims to provide a broad overview of advancements and developments in sorbents with a specific emphasis on the applications of SPE techniques used for antibiotic detection and quantification in various matrices in the last two decades.

Functionalized monolithic columns: Recent advancements and their applications for high-efficiency separation and enrichment in food and medicine

The chromatographic column is the core of a high-performance liquid chromatography (HPLC) system, and must have excellent separation efficiency and selectivity. Therefore, functional modification materials for monolithic columns have been rapidly developed. This study is a systematic review of the recently reported functionalized monolithic columns. In particular, the study reviews the types of functional monomers under different modification conditions, as well as the separation and detection techniques combined with chromatography, and their development prospects. In addition, the applications of functionalized monolithic columns in food analysis, biomedicine, and the analysis of active ingredient of Chinese herbal medicines in recent years are also discussed. Also reviewed are the functionalized monolithic columns for qualitative and quantitative analysis. It provided a reference for further development and application of organic polymer monolithic columns.

Rapid and sensitive analytical method for the determination of amoxicillin and related compounds in water meeting the requirements of the European union watch list

The presence of antibiotics in the aquatic environment is becoming one of the main research focus of scientists and policy makers. Proof of that is the inclusion of four antibiotics, amongst which is amoxicillin, in the EU Watch List (WL) (Decision 2020/1161/EU)) of substances for water monitoring. The accurate quantification of amoxicillin in water at the sub-ppb levels required by the WL is troublesome due to its physicochemical properties. In this work, the analytical challenges related to the determination of amoxicillin, and six related penicillins (ampicillin, cloxacillin, dicloxacillin, penicillin G, penicillin V and oxacillin), have been carefully addressed, including sample treatment, sample stability, chromatographic analysis and mass spectrometric detection by triple quadrupole. Given the low recoveries obtained using different solid-phase extraction cartridges, we applied the direct injection of water samples using a reversed-phase chromatographic column that allowed working with 100% aqueous mobile phase. Matrix effects were evaluated and corrected using the isotopically labelled internal standard or correction factors based on signal suppression observed in the analysis of spiked samples. The methodology developed was satisfactorily validated at 50 and 500 ng L ^- 1 for the seven penicillins studied, and it was applied to different types of water matrices, revealing the presence of ampicillin in one surface water sample and cloxacillin in three effluent wastewater samples.

Selective and fast removal and determination of β-lactam antibiotics in aqueous solution using multiple templates imprinted polymers based on magnetic hybrid carbon material

Selective and fast adsorption of five broad-spectrum β-lactam antibiotics included amoxicillin, cephalexin, cefazolin, penicillin G and oxacillin was achieved by novel surface molecular imprinting polymers (MIPs) with magnetic hybrid carbon material as the substrate. The characteristics of MIPs were studied by scanning electron microscope, Fourier transform infrared spectrometer, thermogravimetric analysis, etc. And through a series of adsorption experiments to examine the kinetics, isotherms, thermodynamics, selectivity and reusability for sorption of β-lactam antibiotics onto the MIPs. The adsorption equilibriums were accomplished in about 60 min with adsorption capacities of 4.57-24.55 mg g^-1, while the adsorption process was preferably fitted with pseudo-second-order kinetic model and Freundlich model. The imprinting factors ranged from 1.88 to 9.94 indicated the MIPs possessed excellent recognition ability, and its good reusability was demonstrated after five times adsorption-desorption cycles without a large drop in adsorption capacity. Furthermore, a new detection method was developed by combining of MIPs with solid phase extraction and high performance liquid chromatography (MIPs-SPE-HPLC). Under the optimal SPE conditions, the limits of detection (LODs) for the five BLAs were 0.24-0.56 µg L^-1, with RSDs of 0.76-5.39%. The synthesized MIPs and the proposed MIPs-SPE-HPLC method can be applied for the efficient, simultaneous separation and detection of BLAs.

Occurrence and distribution of selected antibiotics in the surface waters and ecological risk assessment based on the theory of natural disaster

With increasing population growth and resource depletion, ecological health is a hotspot and urgent topic. Our study investigated the occurrence and distribution of five antibiotics, i.e., metronidazole (MET), sulfamethoxazole (SMZ), ciprofloxacin (CFX), norfloxacin (NFX), and enrofloxacin (EFX), in the surface water from Erlong Lake, China. With the seasonal and spatial variations of antibiotics, this study developed an interdisciplinary approach for the ecological risk of antibiotics considering the natural, human, and socioeconomic elements of watershed based on the risk theory of natural disaster. This approach integrates the geographic information system (GIS) spatial analysis tool, natural disaster theory, "driving force"-"pressure"-"state"-"impact"-"response" (DPSIR) model, and ordered weighted averaging (OWA) operators in terms of various environmental factors, representing a new ecological risk paradigm for environmental managers or decision-makers to identify environmental change. A total of 69 samples were collected in wet, dry, and normal seasons from 2017 to 2018, and laboratory analyses revealed that four antibiotics (MET, SMZ, CFX, and NFX) were widely detected in the lake. The mean concentrations decreased in the order of MET (1041.7 ng L^-1) > SMZ (771.4 ng L^-1) > CFX (646.4 ng L^-1) > NFX (179.0 ng L^-1) > EFX (15.3 ng L^-1), with their levels in natural surface waters higher than those in other studies. Antibiotic concentrations were higher in dry seasons than in other seasons, and the concentrations were strongly correlated with EC (electrical conductivity), pH, DOC (dissolved organic carbon), and TP (total phosphorus) according to redundancy analysis (RDA). Significant seasonal variations were found in CFX and EFX (ANOVA, p < 0.001). For the whole watershed, the ecological extremely and heavily vulnerable levels were concentrated in the central and northwest regions of the watershed, i.e., Changling county and Lishu county. Hence, the ecological distributions of extreme risk and heavy risk posed by the five selected antibiotics were assessed by using the mixture hazard quotient methods and DPSIR model which were also located in these counties in different seasons. The antibiotic results of ecosystem risk assessment can support decision-makers in identifying and prioritizing the necessary taking of specific measures and different risk attitudes to preserve the quality of ecological health for a city or multiple counties.

Polypyrrole-Modified Nylon 6 Nanofibers as Adsorbent for the Extraction of Two β-Lactam Antibiotics in Water Followed by Determination with Capillary Electrophoresis

A solid phase membrane adsorbent—a nylon 6 nanofibers membrane coated by polypyrrole (PPy-PA6-NFsM)—was firstly synthesized and used for extraction of two β-lactam antibiotics (oxacillin and cloxacillin) in urban river water. Then the analytes were detected by capillary electrophoresis with a diode array detector (CE-DAD). The synthesized nanofibers membrane was characterized by scanning electron microscopy and a Fourier transform infrared spectrometer. The experimental conditions were optimized, including the amount used of PPy-PA6-NFsM, pH of the sample solutions, adsorption volume, and desorption conditions. Under the optimal extraction and separation conditions, the detection limits were found to be 2.0 ng/mL for both oxacillin and cloxacillin. The proposed method was applied to the determination of the two β-lactams in water samples of an urban river. The recoveries of these two β-lactams were found to be in the range 84.2–96.4%, demonstrating that PPy-PA6-NFsM has a high extraction capability for these two antibiotics. The relative standard deviations, ranging from 2.26% to 5.29% for intraday measurements and from 2.38% to 7.02% for inter-day determinations, were derived respectively.

Separation/Preconcentration Techniques for Rare Earth Elements Analysis

The main aim of this chapter exactly characterizes the contribution. The analytical chemistry of the rare earth elements (REEs) very often is highly complicated and the determination of a specific element is impossible without a sample pre-concentration. Sample preparation can be carried out either by separation of the REEs from the matrix or by concentrating the REEs. The separation of REEs from each other is mainly made by chromatography.

At the beginning of REE analysis, the method of precipitation/coprecipitation was applied for the treatment of REE mixtures. The method is not applicable for the separation of trace amounts of REEs. The majority of the methods used are based on the distribution of REEs in a two-phase system, a liquid–liquid or a liquid–solid system. Various techniques have been developed for the liquid–liquid extraction (LLE), in particular the liquid phase micro-extraction. The extraction is always combined with a pre-concentration of the REEs in a single drop of extractant or in a hollow fiber filled with the extractant. Further modified techniques for special applications and for difficult REE separation have been developed. Compared to the LLE, the solid phase micro-extraction is preferred. The method is robust and easy to handle, in which the solid phase loaded with the REEs can be used directly for subsequent determination methods. At present, very new solid materials, like nanotubes, are developed and tested for solid phase extraction.

New trends in sample preparation techniques for environmental analysis

Environmental samples include a wide variety of complex matrices, with low concentrations of analytes and presence of several interferences. Sample preparation is a critical step and the main source of uncertainties in the analysis of environmental samples, and it is usually laborious, high cost, time consuming, and polluting. In this context, there is increasing interest in developing faster, cost-effective, and environmentally friendly sample preparation techniques. Recently, new methods have been developed and optimized in order to miniaturize extraction steps, to reduce solvent consumption or become solventless, and to automate systems. This review attempts to present an overview of the fundamentals, procedure, and application of the most recently developed sample preparation techniques for the extraction, cleanup, and concentration of organic pollutants from environmental samples. These techniques include: solid phase microextraction, on-line solid phase extraction, microextraction by packed sorbent, dispersive liquid-liquid microextraction, and QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe).

Analysis of drugs in plasma samples from schizophrenic patients by column-switching liquid chromatography-tandem mass spectrometry with organic-inorganic hybrid cyanopropyl monolithic column

This study reports on the development of a rapid, selective, and sensitive column-switching liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to analyze sixteen drugs (antidepressants, anticonvulsants, anxiolytics, and antipsychotics) in plasma samples from schizophrenic patients. The developed organic-inorganic hybrid monolithic column with cyanopropyl groups was used for the first dimension of the column-switching arrangement. This arrangement enabled online pre-concentration of the drugs (monolithic column) and their subsequent analytical separation on an XSelect SCH C18 column. The drugs were detected on a triple quadrupole tandem mass spectrometer (multiple reactions monitoring mode) with an electrospray ionization source in the positive ion mode. The developed method afforded adequate linearity for the sixteen target drugs; the coefficients of determination (R(2)) lay above 0.9932, the interassay precision had coefficients of variation lower than 6.5%, and the relative standard error values of the accuracy ranged from -14.0 to 11.8%. The lower limits of quantification in plasma samples ranged from 63 to 1250pgmL(-1). The developed method successfully analyzed the target drugs in plasma samples from schizophrenic patients for therapeutic drug monitoring (TDM).