Determination of antimicrobial residues and metabolites in the aquatic environment by liquid chromatography tandem mass spectrometry

Antimicrobials are used in large quantities in human and veterinary medicine. Their environmental occurrence is of particular concern due to the potential spread and maintenance of bacterial resistance. After intake by the organisms, the unchanged drug and its metabolized forms are excreted and enter wastewater treatment plants where they are mostly incompletely eliminated, and are therefore eventually released into the aquatic environment. The reliable detection of several antimicrobials in different environmental aqueous compartments is the result of great improvements achieved in analytical chemistry. This article provides an overview of the more outstanding analytical methods based on liquid chromatography tandem mass spectrometry, developed and applied to determine antimicrobial residues and metabolites present in surface, waste, and ground waters.      

Tandem Guest-Host-Receptor Recognitions Precisely Guide Ciprofloxacin to Eliminate Intracellular Staphylococcus aureus

Staphylococcus aureus (S. aureus) is able to hide within host cells to escape immune clearance and antibiotic action, causing life-threatening infections. To boost the therapeutic efficacy of antibiotics, new intracellular delivery approaches are urgently needed. Herein, by rational design of an adamantane (Ada)-containing antibiotic-peptide precursor Ada-Gly-Tyr-Val-Ala-Asp-Cys(StBu)-Lys(Ciprofloxacin)-CBT ( Cip-CBT-Ada ), we propose a strategy of tandem guest-host-receptor recognitions to precisely guide ciprofloxacin to eliminate intracellular S. aureus. Via guest-host recognition, Cip-CBT-Ada is decorated with a β-cyclodextrin-heptamannoside ( CD-M ) derivative to yield Cip-CBT-Ada/CD-M , which is able to target mannose receptor-overexpressing macrophages via multivalent ligand-receptor recognition. After uptake, Cip-CBT-Ada/CD-M undergoes caspase-1 (an overexpressed enzyme during S. aureus infection)-initiated CBT-Cys click reaction to self-assemble into ciprofloxacin nanoparticle Nano-Cip . In vitro and in vivo experiments demonstrate that, compared with ciprofloxacin or Cip-CBT-Ada , Cip-CBT-Ada/CD-M shows superior intracellular bacteria elimination and inflammation alleviation efficiency in S. aureus-infected RAW264.7 cells and mouse infection models, respectively. This work provides a supramolecular platform of tandem guest-host-receptor recognitions to precisely guide antibiotics to eliminate intracellular S. aureus infection efficiently.     

Multiclass method for the quantification of 92 veterinary antimicrobial drugs in livestock excreta,wastewater, and surface water by liquid chromatography with tandem mass spectrometry

A simple multiresidue method was developed for detecting and quantifying 92 veterinary antimicrobial drugs from eight classes (β‐lactams, quinolones, sulfonamides, tetracyclines, lincomycins, macrolides, chloramphenicols, and pleuromutilin) in livestock excreta and water by liquid chromatography with tandem mass spectrometry. The feces samples were extracted by ultrasound‐assisted extraction with a mixture of acetonitrile/water (80:20, v/v) and edetate disodium, followed by a cleanup using solid‐phase extraction with an amino cartridge. Water samples were purified with hydrophilic–lipophilic balance solid‐phase extraction column. Urine samples were extracted with acetonitrile and edetate disodium. Detection of veterinary antimicrobial drugs was achieved by liquid chromatography with tandem mass spectrometry using both positive and negative electrospray ionization mode. The recovery values of veterinary antimicrobial drugs in feces, urine, and water samples were 75–99, 85–110, and 85–101% and associated relative standard deviations were less than 15, 10, and 8%, respectively. The limits of quantification in feces, urine, and water samples were 0.5–1, 0.5–1, and 0.01–0.05 μg/L, respectively. This method was applied to determine real samples obtained from local farms and provides reliable quantification and identification results of 92 veterinary antimicrobial drugs in livestock excreta and water.     

Determination of pharmaceuticals in environmental and biological matrices using pressurised liquid extraction—Are we developing sound extraction methods?

Pressurised liquid extraction (PLE) is now a well established and extensively applied extraction technique in environmental analysis for pollutants such as persistent organic pollutants (POPs). During the past decade, an emerging group of environmentally interesting analytes are pharmaceuticals that are continuingly released into the environment. This class is comprised with compounds of various properties. As the field of the analysis of these compounds grows, an increasing number of PLE methods for pharmaceuticals of varying quality are developed and published. This review summarises the critical PLE parameters during PLE method development and highlight them with examples from recently published papers utilising pressurised liquid extraction for the determination of pharmaceuticals in environmental and biological matrices. These recent methods are summarised and critically discussed with the aim to provide important reflections to alleviate in future PLE development for pharmaceuticals in environmental matrices.     

Antimicrobial activities,toxicity and phenolic composition of Asphodeline anatolica E. Tuzlaci leaf extracts from Turkey

The antimicrobial activity of acetone, methanol and aqueous extracts of Asphodeline anatolica E. Tuzlaci leaves was evaluated against American type culture collection, food and clinical isolates (Listeria monocytogenes and Staphylococcus aureus including methicillin-resistant strains-MRSA). Biofilm formation, toxicity and characterisation of the polyphenolic content were analysed. The acetone extract demonstrated a higher antibacterial activity against S. aureus including MRSA strains, L. monocytogenes and Pseudomonas aeruginosa than against other extracts. No effect was observed in biofilm formation. The extracts resulted non-toxic against Artemia salina Leach. The phytochemical screening of extracts indicated that they mainly contained six polyphenols identified as catechin 3-O-gallate, protocatechuic acid, diosmin, rutin, cirsimaritin and kaempferol glucoside. This study is the first report on antimicrobial activity and phenolic content of A. anatolica and contributes to enrich the literature data on the biological properties of this plant. A. anatolica leaves have a potential as source of natural antimicrobial compounds.     

Synthesis,characterization, and antimicrobial activities of barbital-based alkaline earth metal complexes: the X-ray crystal structure of [Ba2H(Barb)5] (Barb = 5,5-diethyl barbiturate)

Three barbital-based alkaline earth metal complexes, [Ca(Barb)₂]?·?3H₂O (1), [Ba₂H(Barb)₅] (2) and [Mg(Barb)₂]?·?2H₂O (3) (Barb?=?5,5-diethyl barbiturate sodium salt), were synthesized and characterized with elemental analysis, thermal analysis, and infrared, Raman, ultraviolet, and NMR (¹H and ¹³C) spectroscopies. Single-crystal X-ray diffraction studies reveal that 2 is a dimer. Each barium(II) is surrounded by an O₇N₂ donor set in an approximate monocapped square antiprism with Ba–O distances ranging from 2.6512(14) to 2.9168(15)?Å and Ba–N distances of 2.7601(15) and 3.2558(17)?Å. The complex forms polymeric networks in the solid state with different coordinating abilities of O and N donors and N–H···O hydrogen bonds. The antimicrobial activities of 1–3 were observed against different gram-positive and gram-negative bacteria, yeast, and molds. Variable antimicrobial activity against the different bacteria strains was observed and compared with that of standard antibiotics; minimum inhibitory concentration values ranged from 22 to 170?µg?mL^?1 for bacteria.     

Extraction and determination of sulfonamides, macrolides, and trimethoprim in sewage sludge

Pressurized liquid extraction (PLE) was optimized and validated for the determination of sulfonamide and macrolide antimicrobials and trimethoprim in sewage sludge samples. A mixture of water/methanol (50:50, v/v) was found as the most efficient extraction solvent. A temperature of 100 degrees C and a pressure of 100 bar were chosen for extraction. Two cycles of 5 min each efficiently extracted at least 97% of the total extractable amount of all studied analytes from activated sludge. The limits of quantification (S/N= 10) varied between 3 and 41 microg/kg dry weight (dw) and the relative recoveries ranged between 78 and 142%. Additionally, the influence of pH and different LC/MS/MS systems on the absolute recoveries was assessed. Of the investigated antimicrobials sulfapyridin, sulfamethoxazole, trimethoprim, azithromycin, clarithromycin and roxithromycin were detected in municipal sewage sludge samples. Concentrations in activated sludge ranged up to 197 microg/kgdw. In comparison, results obtained by ultrasonic solvent extraction were significantly lower for sulfonamides and in tendency lower for macrolides.     

Synthesis and characterization of some tetrazoles and their prospective for aerobic micro-fouling mitigation

Two series of tetrazole derivatives of the type N-(1H-tetrazol-5-yl)-1-(aryl)methanimine (101–106) and 1-(4-alkoxyphenyl)-N-(1H-tetrazol-5-yl)methanimine (107–111) were synthesized and characterized via conventional tools of analysis (elemental analysis, FT-IR and ¹H NMR spectroscopy). These two synthesized series were biologically evaluated for their potentials against some microbial biofilm causing strains (micro bio-foulants). Biological activities were evaluated by MIC values and cell viability percentages of them. In case of compounds (107–111), 107 was the most potent antimicrobial one, where its MIC values were 10.666667 µg/ml; 12.82222 µg/ml and 21.43666 µg/ml for Staphylococcus aureus, Escherichia coli and Candida albicans respectively, whereas compound 106, (of group 101–106), MIC values were 16 µg/ml for all the tested microorganisms. Viability assay showed that 107 activity percentages were 96.99456%, 92.32886% and 89.09558% against Gm +ve bacteria, Gm −ve bacteria and yeast respectively, whereas 106 activity percentages were 95.255569%, 90.204675% and 86.710956% against Gm +ve bacteria, Gm −ve bacteria and yeast respectively. Two antimicrobial mode of actions were proposed and discussed depending on the two evaluated tetrazole groups.     

A fully automated on-line preconcentration and liquid chromatography-tandem mass spectrometry method for the analysis of anti-infectives in wastewaters

We developed and validated a novel on-line preconcentration liquid chromatography-tandem mass spectrometry method for the determination of anti-infectives in wastewaters. The presented method preconcentrates 1 mL of sample in a load column using a switching-valve technique. The method was optimized with respect to sample load flow rate, volume of the load column wash and organic solvent content of the load column wash. The sample is cleaned using a 30% organic solvent washing step and then gradually eluted to an analytical column for separation. To compensate for matrix effects, quantitation was performed using standard additions. Confirmation of the presence of the detected compounds was done using a second selective reaction monitoring transition. Method intra-day precision was less than 9% and inter-day precision %R.S.D. varied between 2.5 and 23%. Limits of detection for the selected anti-infective compounds ranged from 13 to 61 ng L⁻¹. All the target anti-infectives were found in the city of Montréal WWTP effluent in concentrations ranging from 71 to 289 ng L⁻¹. This automated method eases the rapid quantitation of those trace contaminants using small sample volumes.     

Determination of personal care products in sewage sludge by pressurized liquid extraction and ultra high performance liquid chromatography–tandem mass spectrometry

This paper describes a method for the determination of a group of personal care products including four UV filters, four preservatives and two antimicrobials in sewage sludge. The method combines pressurized liquid extraction and ultra high performance liquid chromatography–tandem mass spectrometry. Most of the parameters that affect the extraction step such as temperature, pressure, static extraction time, number of cycles, purge time and flush volume were optimized using a fractional experimental design. In the chromatographic step, the compounds were detected by using tandem mass spectrometry with a triple quadrupole analyzer with electrospray ionization in positive and negative modes. The use of small diameter particles (1.8 μm) in the chromatographic column allowed the compounds to be eluted in 9 min. The entire process took a total of 39 min. All recoveries were higher than 72% except for 2,4-dihydroxybenzophenone (a UV filter), whose recovery was 30%. The repeatability and reproducibility between days expressed as RSD (%) (n = 3) were less than 8% and 13%, respectively. The LODs and LOQs were lower than 8 μg/kg and 12.5 μg/kg of dry weight (d.w.), respectively. When the method was applied to determine the compounds in sewage sludge from a domestic sewage treatment plant, triclosan (an antimicrobial) and octocrylene (a UV filter) showed the highest levels, 1490 μg/kg (d.w.) and 1842 μg/kg (d.w.), respectively. This paper describes for the first time the determination of parabens and two UV filters (octyldimethyl-p-aminobenzoic acid and benzophenone-3) in sewage sludge.