Simultaneous determination of 13 quinolones from feeds using accelerated solvent extraction and liquid chromatography

Immobilized imidazolium-based ionic liquids in C18 for solid-phase extraction

In this work, two solid-phases based on imidazolium-based ionic liquids were obtained and characterized for solid-phase extraction of fluoroquinolones. The process of immobilization was performed replacing a toxic reagent by UV-irradiation to get a harmless process. The obtained solid-phases were characterized by nuclear magnetic resonance spectroscopy and elemental analysis. Each solid-phase was packed in a cartridge and was used in solid-phase extraction processes for norfloxacin and ciprofloxacin, after the optimization of some parameters such as the elution solvent, the eluent volume and, the sample volume to be used during the loading step. The developed solid-phases with immobilized ionic liquids were successfully implemented for the studied compounds and indicate high probabilities to be useful in solid-phase extractions of other fluoroquinolones.

Multi-drug ultraperformance liquid chromatography/tandem mass spectrometry method to quantify antimicrobials in feeding stuffs at carry-over level

RATIONALE

Carry-over is an undesirable contamination from medicated to non-medicated during the production of feedingstuffs. In 2014 the European Parliament and the Council started working to produce a new regulatory act that will fix tolerable levels of drugs by carry-over in non-target feed to have a harmonized practice to evaluate this contamination by veterinary drugs.

METHODS

We developed a rapid and effective multi-analyte method coupling ultraperformance liquid chromatography to tandem mass spectrometry (UPLC/MS/MS) for the detection of 37 drugs belonging to different classes of antimicrobials (sulfonamides, tetracyclines, macrolides, quinolones, pleuromutilins and streptogramins) in feeds at carry-over levels. The method was in-house validated in the concentration range 0.25-2.0 mg kg^-1 , according to the Regulation (UE) 2017/625 requirements and the guideline included in the Commission Decision 2002/657/EC for official methods.

RESULTS

The UPLC/MS/MS method allows the determination of the antimicrobials in 15 min, by providing results compliant to the criteria established by the European Commission legislation. All the analytes showed a limit of detection (LOD) in the range 2.0-5.0 μg kg^-1 and a limit of quantification (LOQ) at 10.0 μg kg^-1 ; oxytetracycline, doxycycline, spiramycin and virginiamycin have a higher LOD and LOQ (15.0 μg kg^-1 ; 30.0 μg kg^-1 , respectively). Recoveries were satisfactory ranging from 90.4% to 103.1%.

CONCLUSIONS

The method is characterized by an effective clean-up of all drugs without the use of large sample size and organic solvent extraction.

Sequential injection analysis for the determination of fluoroquinolone antibacterial drug residues by using eosin Y as complexing agent

A sequential injection analysis (SIA) method was developed for the rapid and sensitive determination of fluoroquinolone residues, including norfloxacin, ciprofloxacin and enrofloxacin, in fish samples. The method is based on the reaction between fluoroquinolone drug and eosin Y in Britton-Robinson buffer (pH 2.0), forming pink colored complexs with maximum absorptions at 522, 525 and 527 nm for norfloxacin, ciprofloxacin and enrofloxacin, respectively. Linearity ranges were found to be 0.05-10.0 mg L^-1 (r² = 0.9996), 0.1-10.0 mg L^-1 (r² = 0.9995) and 0.05-10.0 mg L^-1 (r² = 0.9997) for norfloxacin, ciprofloxacin and enrofloxacin, respectively. The detection limit was found to be in the range of 0.013-0.019 mg L^-1. The method was tested and validated for various parameters according to main guidelines. The proposed SIA method was successfully applied for the determination of fluoroquinolone drug residues in fish samples with the sampling rate of 47 h^-1. The results demonstrated that the method is accurate, precise and reproducible, while being simple, rapid, economical and less time consuming. It can be suitably applied for the estimation of fluoroquinolone drug residues in routine quality control.

Four Specific Hapten Conformations Dominating Antibody Specificity: Quantitative Structure-Activity Relationship Analysis for Quinolone Immunoassay

Antibody-based immunoassay methods have been important tools for monitoring drug residues in animal foods. However, because of limited knowledge about the quantitative structure-activity relationships between a hapten and its resultant antibody specificity, antibody production with the desired specificity is still a huge challenge. In this study, the three-dimensional quantitative structure-activity relationship (3D QSAR) was analyzed in accordance with the cross-reactivity of quinolone drugs reacting with the antibody raised by pipemidic acid as the immunizing hapten and compared with the reported cross-reactivity data and their hapten structures. It was found that the specificity of a quinolone antibody was strongly related to the conformation of the hapten used and that hapten conformations shaped like the letters "I", "P", and "Φ" were essential for the desired high specificity with low cross-reactivity, but that the hapten conformation shaped like the letter "Y" led to an antibody with broad specificity and high cross-reactivity. Almost all of the antibodies against quinolones could result from these four hapten conformations. It was first found that the concrete conformations dominated the specificity of the antibody to quinolone, which will be of significance for the accurate hapten design, predictable antibody specificity, and better understanding the recognition mechanism between haptens and the antibodies for immunoassays.

Review of Properties and Analytical Methods for the Determination of Norfloxacin

The first-generation quinolones have their greatest potency against Gram-negative bacteria, but newly developed molecules have exhibited increased potency against Gram-positive bacteria, and existing agents are available with additional activity against anaerobic microorganisms. Norfloxacin is a broad-spectrum antimicrobial fluoroquinolone used against Gram-positive and Gram-negative organisms (aerobic organisms). There are different analytical methods available to determine norfloxacin applied in quality control of this medicine in order to ensure its effectiveness and safety. The authors present an overview of the fourth generation of quinolones, followed by the properties, applications, and analytical methods of norfloxacin. These results show several existing analytical techniques that are flexible and broad-based methods of analysis in different matrices. This article focuses on bionalytical and pharmaceutical quality-control applications, such as thin-layer chromatography, microbiological assay, spectrophotometry, capillary electrophoresis (CE), and high-performance liquid chromatography (HPLC).

A flow injection chemiluminescence method for determination of nalidixic acid based on KMnO₄-morin sensitized with CdS quantum dots

A simple and sensitive flow injection chemiluminescence (CL) method was developed for determination of nalidixic acid by application of CdS quantum dots (QDs) in KMnO4-morin CL system in acidic medium. Optical and structural features of L-cysteine capped CdS quantum dots which were synthesized via hydrothermal approach were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and ultraviolet-visible (UV-Vis) spectroscopy. Moreover, the potential mechanism of the proposed CL method was described using the results of the kinetic curves of CL systems, the spectra of CL, PL and UV-Vis analyses. The CL intensity of the KMnO4-morin-CdS QDs system was considerably increased in the presence of nalidixic acid. Under the optimum condition, the enhanced CL intensity was linearly proportional to the concentration of nalidixic acid in the range of 0.0013 to 21.0 mg L(-1), with a detection limit of (3σ) 0.003 mg L(-1). Also, the proposed CL method was utilized for determination of nalidixic acid in environmental water samples, and commercial pharmaceutical formulation to approve its applicability. Furthermore, corona discharge ionization ion mobility spectrometry (CD-IMS) method was utilized for determination of nalidixic acid and the results of real sample analysis by two proposed methods were compared. Comparison the analytical features of these methods represented that the proposed CL method is preferable to CD-IMS method for determination of nalidixic acid due to its high sensitivity and precision.

Pharmacological effects of berberine and its derivatives: a patent update

INTRODUCTION

A number of plant-derived agents are used in many therapeutic areas. Berberine, an important protoberberine alkaloid, is present in a number of medicinal plants that have been widely used in traditional Chinese medicine for hundreds of years. Modern research has shown that berberine and its derivatives display several pharmacological effects through various mechanisms.

AREAS COVERED

This review discusses recent and mostly Chinese patents that report the synthesis of berberine, berberine derivatives and berberine salts, and methods of preparation for formulations (traditional Chinese medicine) containing herbal components rich in berberine, along with their applications. The review covers several therapeutic effects of berberine, its derivatives and pharmaceutical formulations against cancer, obesity, diabetes, inflammation, atherosclerosis, Alzheimer's disease, rheumatoid arthritis and cardiovascular diseases. In addition, the mechanisms underlying the pharmacological effects are discussed.

EXPERT OPINION

Modification of the functional groups of berberine has a significant effect on the pharmacological activity. However, studies on altering the atoms and size of the berberine skeleton are rare. Thus, it may be beneficial to initiate a drug development program focused on inserting heterocyclic rings of different sizes into berberine. Furthermore, structural modification to improve the safety, efficacy and selectivity is necessary to promote the use of berberine-based drugs in clinical settings.

Complement fixing polysaccharides from Terminalia macroptera root bark, stem bark and leaves

The root bark, stem bark and leaves of Terminalia macroptera were sequentially extracted with ethanol, 50% ethanol-water, and 50 °C and 100 °C water using an accelerated solvent extractor. Ten bioactive purified polysaccharide fractions were obtained from those crude extracts after anion exchange chromatography and gel filtration. The polysaccharides and their native extracts were characterized with respect to molecular weight, chemical compositions and effects in the complement assay. The chemical compositions showed that the polysaccharides are of pectic nature. The results indicated that there was no great difference of the complement fixation activities in the crude extracts from the different plant parts when extracting with the accelerated solvent extraction system. The purified polysaccharide fractions 100WTSBH-I-I and 100WTRBH-I-I isolated from the 100 °C water extracts of stem and root bark respectively, showed the highest complement fixation activities. These two fractions have rhamnogalacturonan type I backbone, but only 100WTSBH-I-I contains side chains of both arabinogalactan type I and II. Based on the yield and activities of the fractions studied those from the root bark gave highest results, followed by those from leaves and stem bark. But in total, all plant materials are good sources for fractions containing bioactive polysaccharides.

Analysis of fluoroquinolones in animal feeds by liquid chromatography with fluorescence detection

An analytical method for the analysis of six fluoroquinolones (FQs) in animal feeds was developed. The sample treatment consists of a simple and rapid extraction of the analytes by manual shaking with an acetonitrile-water mixture containing hydrochloric acid without further sample cleanup. Matrix effects were minimized by diluting the extract with water. Determination was carried out by liquid chromatography using fluorimetric detection. The method was validated in-house in four different feed matrices (poultry, cow, pig, and lamb feed). Mean recoveries ranging from 80 to 105%, with relative standard deviations below 12%, were achieved from spiked animal feed samples on the 0.2-2.0 μg/g level. No relevant differences were observed between the studied feeds, this ensuring that the method was reliable for a wide variety of feed matrices. Decision limit and detection capability values are below 0.08 and 0.13 mg/kg, respectively, for most FQs. The results obtained demonstrate the feasibility of the analytical method developed for a routine use to control the illegal use of these substances in feeding stuffs.

Determination of Enoxacin in Tablet by Flow Injection Chemiluminescence

A new flow injection chemiluminescence (CL) method for the determination of Enoxacin（ENX）was described. The method was based on the weak CL reaction of Ce(Ⅳ)-SO32- sensitized by Pr3+- ENX. The relative CL intensity was linear with the concentration of ENX in the range of 3×10-8 g•mL-1~5.0×10-7 g•mL-1. The detection limit is 1.0×10-8 g•mL-1 .The rSuperscript textelative standard deviation (RSD) for the determination of 4.0×10-7 g•mL-1 ENX is 3.5% (n=11). The method has been successfully applied to the analysis of ENX in tablet

Development of a multi-class method for the quantification of veterinary drug residues in feedingstuffs by liquid chromatography-tandem mass spectrometry

A simple multi-residue method was developed for detecting and quantifying 33 analytes from 13 classes of antibiotics (tetracyclines (3), quinolones (7), penicillins (3), ionophore coccidiostats (7), macrolides (3), sulfonamides (1), quinoxalines (2), phenicols (2), lincosamides (1), diaminopyrimidines (1), polypeptides (1), streptogramins (1) and pleuromutilins (1)) in animal feeds. Extraction and clean-up procedures were optimized with spiked piglet feed. Samples were extracted by ultrasonic-assisted extraction with a mixture of methanol/acetonitrile/McIlvaine buffer at pH 4.6 (37.5/37.5/25, v/v/v) containing 0.3% of EDTA-Na(2), followed by a clean up using a dispersive solid-phase extraction (d-SPE) with PSA (primary secondary amine). Detection of antibiotics was achieved by liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS) within 28 min using both positive and negative ESI mode. Average recoveries ranged from 51% (oxytetracycline) to 116% (tilmicosin) with associated relative standard deviations of 7.3% and 9.0% and an overall mean of 87%. Limits of quantification ranged from 3.8 ngg(-1) (lincomycin) to 65.0 ngg(-1) (bacitracin). Following optimization, the method was further verified for bovine and lamb feeding stuffs; negative matrix effects were evaluated and overcome by a standard addition method.

Development and validation of a rapid multi-class method for the confirmation of fourteen prohibited medicinal additives in pig and poultry compound feed by liquid chromatography-tandem mass spectrometry

A confirmatory method has been developed to allow for the analysis of fourteen prohibited medicinal additives in pig and poultry compound feed. These compounds are prohibited for use as feed additives although some are still authorised for use in medicated feed. Feed samples are extracted by acetonitrile with addition of sodium sulfate. The extracts undergo a hexane wash to aid with sample purification. The extracts are then evaporated to dryness and reconstituted in initial mobile phase. The samples undergo an ultracentrifugation step prior to injection onto the LC-MS/MS system and are analysed in a run time of 26 min. The LC-MS/MS system is run in MRM mode with both positive and negative electrospray ionisation. The method was validated over three days and is capable of quantitatively analysing for metronidazole, dimetridazole, ronidazole, ipronidazole, chloramphenicol, sulfamethazine, dinitolimide, ethopabate, carbadox and clopidol. The method is also capable of qualitatively analysing for sulfadiazine, tylosin, virginiamycin and avilamycin. A level of 100 microg kg(-1) was used for validation purposes and the method is capable of analysing to this level for all the compounds. Validation criteria of trueness, precision, repeatability and reproducibility along with measurement uncertainty are calculated for all analytes.

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.

Determination of fluoroquinolones in aquaculture products by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)

An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of fluoroquinolones-ciprofloxacin (CIPRO), danofloxacin (DANO), enrofloxacin (ENRO) and sarafloxacin (SARA)-in aquaculture products, specifically salmon, shrimp and tilapia. After initial sample extraction with an acidic acetonitrile solution, the extract was diluted with dichloromethane and centrifuged, then an aliquot was concentrated and applied to a C18 solid-phase extraction cartridge and concentrated for a second time. The resultant residue was dissolved in acetonitrile, diluted with water, and then further defatted with hexane. The fluoroquinolone residues were determined by UPLC with an HSS T3 C18 reverse-phase column using an ammonium hydroxide-formic acid buffer in an acetonitrile gradient with MS/MS detection using multiple reaction monitoring. Average recoveries for salmon tissue ranged from 73% for DANO to 95% for SARA, for shrimp from 71% for DANO to 109% for SARA, and from 62% for DANO to 111% for SARA in tilapia, fortified at the 1.0 ng g(-1) level. Standard curves were linear between 0.002 and 0.5 ng injected for all compounds. Detection limits of 0.2 ng g(-1) for CIPRO, DANO, ENRO, and SARA were easily obtainable. The operational errors, interferences, and recoveries for fortified samples demonstrate that this described method is suitable for routine use in a regulatory programme. The recommended method is simple, rapid, specific and reliable for the routine monitoring of fluoroquinolone residues in aquatic species such as salmon, tilapia and shrimp.

Chromatographic analysis of banned antibacterial growth promoters in animal feed

The issue of antimicrobial use in animals used as food is of global concern. Antimicrobials are used in animal agriculture to improve health and welfare of animals, meat quality, the economic efficiency of growth and production and public health by decreasing shedding of zoonotic pathogens. However, large quantities are often used without professional supervision. The growth-promotant (now reclassified as zootechnical feed additives) effect of low levels of antibiotics in animal feeds was first described in the late 1940s. Already in 1969 the Swann Committee recommended that use of antibiotics as a supplement in animal feedstuff should be restricted to those with little or no application as therapeutic agents for humans and animals, which would not impair the efficacy of therapeutic antibiotics through the development of resistant strains of organisms. Antimicrobials like avoparcin, ardacin, zinc bacitracin, virginiamycin, tylosin, spriramycin, carbadox and olaquindox were withdrawn within the period 1997-1999. Four others (monensin sodium, salinomycin sodium, avilamycin and flavophospholipol) were still permitted for use as growth promoters in animal feed to animals marketed in the European Union (EU). Since January 2006, they have been banned as well. This review focuses on the analytical methods developed to be an effective tool for monitoring compliance with the ban.