Analysis of antibiotics in urine and wipe samples from environmental and biological monitoring—Comparison of HPLC with UV-, single MS- and tandem MS-detection

Multi-class/residue method for determination of veterinary drug residues, mycotoxins and pesticide in urine using LC-MS/MS technique

BACKGROUND

Veterinary drugs are widely used in animals to prevent diseases and are a complex set of drugs with very different chemical properties. Multiclass and multi-residue methods for simultaneous detection of residues from veterinary drugs and contaminants in urine are very rare or non-existent. Therefore, the aim of this study was to develop and validate a sensitive and reliable quantitative LC-MS/MS method for simultaneous determination of a wide range of veterinary drug and pesticide residues and mycotoxins in bovine urine. This involved 42 veterinary drug residues (4 thyreostats, 6 anabolic hormones, 2 lactones, 10 beta agonists, 15 antibiotics, 5 sulphonamides), 28 pesticides and 2 mycotoxins. Stable isotopically labelled internal standards were used to facilitate effective quantification of the analytes. Analysis was performed in both positive and negative ionization modes with multiple reaction monitoring transitions over a period of 12 min.

RESULTS

The parameters validated included linearity, limit of detection (LOD), limit of quantification (LOQ), detection capability (CCβ), decision limit (CCα), stability, accuracy and precision. The process followed guidelines of the regulation 2021/808/EC. The calibration curves were linear with coefficient of correlation (R2) from 0.991 to 0.999. The LODs were from 0.01 to 2.71 µg/L, while the LOQs were from 0.05 to 7.52 µg/L. The CCα and CCβ were in range 0.05-12.11 µg/L and 0.08-15.16 µg/L. In addition, the average recoveries of the spiked urine samples were from 71.0 to 117.0% and coefficient of variation (CV) < 21.38% (intraday and interday).

CONCLUSION

A new isotopic LC-MS/MS method has been developed, validated and applied for identification and quantification of 72 residues of veterinary drugs and pesticides and other contaminants such as mycotoxins in bovine urine. The most appropriated sample preparation procedures involved sodium acetate buffer, enzymatic hydrolysis using β-glucuronidase and cleanup solid phase extraction with OASIS SPE cartridges. The parameters were satisfactorily validated fulfilling requirements under Regulation 2021/808/EC. Consequently, the method could be used in routine analysis of bovine urine samples for simultaneous detection of veterinary drug and pesticide residues as well as contaminants such as mycotoxins.

Metal-organic framework-based nanomaterials as opto-electrochemical sensors for the detection of antibiotics and hormones: A review

Increasing trace levels of antibiotics and hormones in the environment and food samples are concerning and pose a threat. Opto-electrochemical sensors have received attention due to their low cost, portability, sensitivity, analytical performance, and ease of deployment in the field as compared to conventional expensive technologies that are time-consuming and require experienced professionals. Metal-organic frameworks (MOFs) with variable porosity, active functional sites, and fluorescence capacity are attractive materials for developing opto-electrochemical sensors. Herein, the insights into the capabilities of electrochemical and luminescent MOF sensors for detection and monitoring of antibiotics and hormones from various samples are critically reviewed. The detailed sensing mechanisms and detection limits of MOF sensors are addressed. The challenges, recent advances, and future directions for the development of stable, high-performance MOFs as commercially viable next-generation opto-electrochemical sensor materials for the detection and monitoring of diverse analytes are discussed.

A selective analysis of sulfamethoxazole - Trimethoprim in tablet formulations using graphene oxide-zinc oxide quantum dots based nanocomposite modified glassy carbon electrode

In this study, simultaneous analysis on electrochemical detection of SMX and TMP in tablet formulation has been made using graphene oxide (GO) and ZnO QDs (GO-ZnO QDs) based nanocomposite modified glassy carbon electrode (GCE). The functional group presence was observed using FTIR study. The electrochemical characterization for GO, ZnO QDs and GO-ZnO QDs was studied using cyclic voltammetry using [Fe(CN)₆]^3- medium. In order to estimate the electrochemical redox behavior of SMX and TMP from tablet, the developed electrodes GO/GCE, ZnO QDs/GCE and GO-ZnO QDs/GCE are initially tested for electrochemical activity towards the SMX tablet in BR pH 7 medium. Later their electrochemical sensing has been monitored using square wave voltammetry (SWV). On observing the characteristic behavior of developed electrodes, GO/GCE exhibited detection potential of +0.48 V for SMX and +1.37 V for TMP whereas, ZnO QDs/GCE with +0.78V for SMX and for TMP 1.01 V respectively. Similarly, for GO-ZnO QDs/GCE, its 0.45 V for SMX and 1.11 V for TMP are observed using cyclic voltammetry. The obtained potential results on detecting SMX and TMP are in good agreement with previous results. Under optimized conditions, the response has been monitored with linear concentration range 50 μg/L to 300 μg/L for GO/GCE, ZnO QDs/GCE and GO-ZnO QDs/GCE in SMX tablet formulations. Their detection limits for the individual detection using GO-ZnO/GCE for SMX and TMP are found to be 0.252 ng/L and 19.10 μg/L and for GO/GCE it was 0.252 pg/L and 2.059 ng/L respectively. It was observed that ZnO QDs/GCE could not provide the electrochemical sensing towards SMX and TMP which may be due to the ZnO QPs can act as a blocking layer impeding the electron transfer process. Thus, the sensor performance lead to promising biomedical applications in real-time monitoring on evaluating selective analysis with SMX and TMP in tablet formulations.

Rapid electrochemical recognition of trimethoprim in human urine samples using new modified electrodes (CPE/Ag/Au NPs) analysing tunable electrode properties: experimental and theoretical studies

Pharmaceutical effluents are a serious environmental issue, which require to be treated by a suitable technique; thus, the electrochemical process is actively considered as a viable method for the treatment. In this work, new carbon paste electrodes (CPEs) were fabricated by compressing gold and silver nanoparticles (NPs), namely, CPE/Ag NPs, CPE/Au NPs, and CPE/Ag/Au NPs and then completely characterized by different analytical methods. The performance of the electrodes was studied after determining their surface area (×10^-6 cm²) as 4.17, 5.05, 5.27, and 5.12, producing high anodic currents for K₄[Fe(CN)₆] compared to the commercial electrode. This agrees with the results of impedance study, where the electron transfer rate constants (k_app, ×10^-3 cm s^-1) were determined to be 28.7, 42.6, 41.0, and 101.4 for CPE, CPE/Ag NPs, CPE/Au NPs, and CPE/Ag/Au NPs, respectively, through the Bode plot-phase shifts. This is consistent with the charge transfer resistance (R_CT, Ω), resulting as 171 for CPE/Ag/Au NPs < 395 for CPE/Ag NPs < 427 for CPE/Au NPs and < 742 for CPE. Therefore, these electrodes were employed to detect trimethoprim (TMP) since metallic NPs contribute good crystallinity, stability, conduciveness, and surface plasmon resonance to the CPE, convalescing the sensitivity; comprehensively, they were applied for its detection in real water and human urine samples, and the limit of detection (LOD) was as low as 0.026, 0.032, and 0.026 μmol L^-1 for CPE/Ag NPs, CPE/Au NPs, and CPE/Ag/Au NPs, respectively. In contrast, unmodified CPE was unable to detect TMP due to the lack of efficiency. The developed technique shows excellent electrochemical recovery of 92.3 and 97.1% in the urine sample. Density functional theory (DFT) was used to explain the impact of the metallic center in graphite through density of states (DOS).

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.

An Easy Procedure to Quantify Anticoagulant Rodenticides and Pharmaceutical Active Compounds in Soils

A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction was validated for the extraction of seven coumarin anticoagulant rodenticides (ARs) and 36 pharmaceutical active compounds (PhACs) residues in soil samples using liquid chromatography tandem mass spectrometry (LC-MS/MS). The aim of this work was to develop a method for the monitoring of these compounds in agricultural lands as well as in forensic applications for the determination of ARs poisoning. As far as is known, this is the first time that a QuEChERS-based method is used for the extraction of ARs in soil, as well as on such a quantity of PhACs. A matrix effect study was carried out on samples of soil devoted to agriculture in the midland area of the Canary Islands (clay loam type). It was in house validated (accuracy, precision, and linearity) at seven spiked levels between 0.5 and 50 ng g⁻¹. The limits of quantification (LOQ) ranged between 0.5 and 50.0 ng g⁻¹ and the limits of detection (LOD) ranged from 0.024 to 6.25 ng g⁻¹. The method was then successfully used for both the determination of the target analytes in the soils from the agricultural plots that had been irrigated with regenerated water, and in the soil collected from underneath wild bird carcasses (which had been the subject of forensic investigation).

Pharmacokinetic comparison with different assays for simultaneous determination of cis-, trans-cefprozil diastereomers in human plasma

The purpose of this study was to compare pharmacokinetic (PK) parameters obtained using two newly developed assays, HPLC-UV and UPLC-ESI-MS/MS. Selection of assay and results obtained therefrom are very important in PK studies and can have a major impact on the PK-based clinical dose and usage settings. For this study, we developed two new methods that are most commonly used in biosample analysis and focused on PK parameters obtained from them. By HPLC-UV equipped with a Luna-C₈ column using UV detector, cefprozil diastereomers were separated using water containing 2% (V/V) acetic acid and acetonitrile as a mobile phase. By UPLC-ESI-MS/MS equipped with a HALO-C₁₈column, cefprozil diastereomers were separated using 0.5% (V/V) aqueous formic acid containing 5 mM ammonium-formate buffer and methanol as a mobile phase. Chromatograms showed high resolution, sensitivity, and selectivity without interference by plasma constituents. Both intra- and inter-day precisions (CV, %) were within 8.88% for HPLC-UV and UPLC-ESI-MS/MS. Accuracy of both methods was 95.67%–107.50%. These two analytical methods satisfied the criteria of international guidance and could be successfully applied to PK study. Comparison of PK parameters between two assays confirmed that there is a difference in the predicted minimum plasma concentrations at steady state, which may affect clinical dose and usage settings. Furthermore, we confirmed possible correlation between PK parameters and various biochemical parameters after oral administration of 1000 mg cefprozil to humans.

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Development of UPLC-ESI-MS/MS and HPLC-UV methods for cefprozil diastereomers.

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Comparison of PK parameters obtained using two newly developed assays.

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Possible correlation between PK parameters and various biochemical parameters.

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.

Analysis of the retention of tetracyclines on reversed-phase columns: Chemometrics, design of experiments and quantitative structure-property relationship (QSPR) study for interpretation and optimization

In this study, design of experiments was applied for the analysis of 6 reversed phase U-HPLC columns used for the separation of four tetracyclines (TCs): tetracycline, doxycycline, chlortetracycline and oxytetracycline in different elution conditions. In a first part, a fractional factorial design (2^4-1) was used to study the influence of four chromatographic parameters: column temperature, pH, flow rate and composition of the mobile phase (i.e. nature of the solvent used as the organic modifier), on the quality of the separation, which was evaluated in terms of peak width and resolution between two pairs of TCs. This experimental design revealed that the nature of the solvent: acetonitrile (ACN) or methanol (MeOH), and the mobile phase flow rate were the two main factors actually having the most influence on the quality of the separation. Moreover, these two factors presented an antagonistic influence according to the response considered: peak width or peak resolution. In order to understand this behavior, a Doehlert design was performed in the second part. It consisted in modeling the evolution of responses as a function of the two main factors: nature of the composition of the mobile phase (mix of ACN and MeOH, from 100% ACN to 100% MeOH) and mobile phase flow rate (from 0.3 to 0.8 mL min^-1). For all the reversed phase columns studied, an inversion of the elution order of TCs and an increase of the retention factors was observed according to the composition of the organic mixture at the end of the gradient. To understand the modification of the interactions implied in the various retention modes related to the selectivity of the organic solvents used, a quantitative structure-property relationship (QSPR) study was achieved. In this final study, the molecular descriptors of each TCs were connected to its retention factor.

UPLC-MS/MS method validation of ciprofloxacin in human urine: Application to biodegradability study in microbial fuel cell

To enable the reliable quantification of ciprofloxacin in human urine, a sensitive and selective assay based on liquid chromatography-tandem mass spectrometry was developed. The chromatographic separation of the ciprofloxacin was carried out on a Zorbex Eclipse C₁₈ column using methanol and ammonium acetate as a mobile phase by the gradient elution method. The developed assay covered a wide range of concentrations (1.56-100 ng/mL) with a lower limit of detection of 0.76 ng/mL. Quantification was performed using the multiple reaction monitoring transitions 331.8/231 for ciprofloxacin and 362/318 for ofloxacin (internal standard). This assay was validated for linearity, accuracy, precision and recovery. The validated method was then applied to the biodegradability of ciprofloxacin (99%) from human urine in the microbial fuel cell.

Aptamer-mediated colorimetric method for rapid and sensitive detection of chloramphenicol in food

We report an aptamer-mediated colorimetric method for sensitive detection of chloramphenicol (CAP). The aptamer of CAP is immobilized by the hybridization with pre-immobilized capture probe in the microtiter plate. The horseradish peroxidase (HRP) is covalently attached to the aptamer by the biotin-streptavidin system for signal production. CAP will preferably bind with aptamer due to the high binding affinity, which attributes to the release of aptamer and HRP and thus, affects the optical signal intensity. Quantitative determination of CAP is successfully achieved in the wide range from 0.001 to 1000 ng/mL with detection limit of 0.0031 ng/mL, which is more sensitive than traditional immunoassays. This method is further validated by measuring the recovery of CAP spiked in two different food matrices (honey and fish). The aptamer-mediated colorimetric method can be a useful protocol for rapid and sensitive screening of CAP, and may be used as an alternative means for traditional immunoassays.

Synthesis and characterization of triazole based supramolecule for interaction with cefuroxime in tap water and blood plasma

In this study a new calix[4]arene triazole 5 was successfully synthesized using click reaction and characterized through UV-visible, FT-IR, ¹H NMR spectroscopes and Mass Spectrometry. The supramolecular interaction of compound 5 towards commonly used drugs has been carried out using UV-Visible spectroscopy. The supramolecule 5 showed characteristic enhancement in the absorbance intensity after mixing with Cefuroxime at pH (2-12). Compound 5 displayed considerably good interactions with cefuroxime in the presence of other drugs. Compound 5 exhibits linear relationship with cefuroxime concentration in the range of (10-80µM) with regression value of 0.9954. The standard deviation for 50µM Cefuroxime was found to be 0.01 and the limit of detection for cefuroxime was calculated to be 2µM. Job's plot experiments showed 1:1 (5: cefuroxime) binding stoichiometry between compound 5 and cefuroxime. Supramolecule 5 displayed fairly good spectrophotometric recognition of Cefuroxime in human blood plasma and tap water thus showing that the ingredients of tap water and plasma sample was inert in the recognition of cefuroxime.

Novel label-free and high-throughput microchip electrophoresis platform for multiplex antibiotic residues detection based on aptamer probes and target catalyzed hairpin assembly for signal amplification

Novel label-free and multiplex aptasensors have been developed for simultaneous detection of several antibiotics based on a microchip electrophoresis (MCE) platform and target catalyzed hairpin assembly (CHA) for signal amplification. Kanamycin (Kana) and oxytetracycline (OTC) were employed as models for testing the system. These aptasensors contained six DNA strands termed as Kana aptamer-catalysis strand (Kana apt-C), Kana inhibit strand (Kana inh), OTC aptamer-catalysis strand (OTC apt-C), OTC inhibit strand (OTC inh), hairpin structures H1 and H2 which were partially complementary. Upon the addition of Kana or OTC, the binding event of aptamer and target triggered the self-assembly between H1 and H2, resulting in the formation of many H1-H2 complexes. They could show strong signals which represented the concentration of Kana or OTC respectively in the MCE system. With the help of the well-designed and high-quality CHA amplification, the assay could yield 300-fold amplified signal comparing that from non-amplified system. Under optimal conditions, this assay exhibited a linear correlation in the ranges from 0.001ngmL^-1 to 10ngmL^-1, with the detection limits of 0.7pgmL^-1 and 0.9pgmL^-1 (S/N=3) toward Kana and OTC, respectively. The platform has the following advantages: firstly, the aptamer probes can be fabricated easily without labeling signal tags for MCE detection; Secondly, the targets can just react with probes and produce the amplified signal in one-pot. Finally, the targets can be simultaneously detected within 10min in different channels, thus high-throughput measurement can be achieved. Based on this work, it is estimated that this detection platform will be universally served as a simple, sensitive and portable platform for antibiotic contaminants detection in biological and environmental samples.

Mass Spectral Profile for Rapid Differentiating Beta-Lactams from Their Ring-Opened Impurities

High performance liquid chromatography tandem mass spectrometry (HPLC MS) has been widely used for β-lactam antibiotics determination. However, its application to identify impurities of these frequently used drugs is not sufficient at present. In this job, characteristic profiles of the collision induced dissociation (CID) spectra of both β-lactams and ring-opened β-lactams were extracted from the MS data of six β-lactam antibiotics and their forty-five impurities, and were confirmed by the MS data reported in the literature. These characteristics have been successfully applied to rapid differentiation of β-lactam and ring-opened β-lactam impurities in cefixime, cefdinir, and cefaclor. However, these characteristic profiles can only be obtained under low activating voltage. They did not display in the high energy activated CID spectra. Diagnostic fragmentations for determining the localization of double bond and substituents on the thiazine ring and the side chain were also observed. In addition, several characteristic fragmentations are hopeful to be used to differentiate the configurations of C-2 on the thiazine ring of ring-opened impurities, which is generally disadvantageous of mass spectrometry. Taken together, forty-five impurities were identified from the capsules of cefixime, cefdinir, and cefaclor.

Multiresidue analysis of fluoroquinolone antimicrobials in chicken meat by molecularly imprinted solid-phase extraction and high performance liquid chromatography

This paper describes the synthesis of novel molecularly imprinted polymer (MIP) micro-beads for the selective extraction (MISPE) of six fluoroquinolone (FQ) antibiotics (enrofloxacin, ciprofloxacin, lomefloxacin, danofloxacin, sarafloxacin and norfloxacin) from chicken muscle samples and further analysis by high-performance liquid chromatography (HPLC) with fluorescence (FLD) or mass spectrometry (MS) detection. A combinatorial screening approach has been applied to select the optimal functional monomer and cross-linker formulation for polymer synthesis. The MIP prepared using enoxacin (ENOX) as the template - a mixture of methacrylic acid (MAA) and trifluoromethacrylic acid (TFMAA) as functional monomers and ethylene glycol dimethacrylate (EDMA) as the cross-linker - showed superior FQ recognition properties than the rest of the materials generated. MIP spherical particles were prepared using silica beads as sacrificial scaffolds. The polymers were packed in solid phase extraction (SPE) cartridges. The optimized MISPE-HPLC method allows the extraction of the antimicrobials from aqueous samples followed by a selective washing with acetonitrile/water (0.005% TFA, pH=3.0), 20:80 (v/v) and elution with 5% trifluoroacetic acid in methanol. Optimum MISPE conditions led to recoveries of the target FQs in chicken muscle samples ranging between 68 and 102% and precisions in the 3-4% range (RSD, n=18). The method has been validated according to European Union Decision 2002/657/EC, in terms of linearity, accuracy, precision, selectivity, decision limit (CCα) and detection capability (CCβ) by HPLC-FLD and HPLC-MS/MS. The limits of detection were improved using HPLC-MS/MS analysis and ranged between 0.2 and 2.7μgkg(-1) (S/N=3) for all the FQs tested.

Aptasensing of chloramphenicol in the presence of its analogues: reaching the maximum residue limit

A novel, label-free folding induced aptamer-based electrochemical biosensor for the detection of chloramphenicol (CAP) in the presence of its analogues has been developed. CAP is a broad-spectrum antibiotic that has lost its favor due to its serious adverse toxic effects on human health. Aptamers are artificial nucleic acid ligands (ssDNA or RNA) able to specifically recognize a target such as CAP. In this article, the aptamers are fixed onto a gold electrode surface by a self-assembly approach. In the presence of CAP, the unfolded ssDNA on the electrode surface changes to a hairpin structure, bringing the target molecules close to the surface and triggering electron transfer. Detection limits were determined to be 1.6 × 10(-9) mol L(-1). In addition, thiamphenicol (TAP) and florfenicol (FF), antibiotics with a structure similar to CAP, did not influence the performance of the aptasensor, suggesting a good selectivity of the CAP-aptasensor. Its simplicity and low detection limit (because of the home-selected aptamers) suggest that the electrochemical aptasensor is suitable for practical use in the detection of CAP in milk samples.

Simultaneous spectrophotometric estimation of nitazoxanide and ofloxacin in tablets

Two simple, accurate and precise spectrophotometric methods have been developed for simultaneous determination of nitazoxanide and ofloxacin in tablets. Method I is Q-absorbance ratio method which involves Q-absorbance at isobestic point (306.25 nm) and max (347.5 nm) of nitazoxanide, while method II is two wavelength method, where 244.6 nm and 273.0 nm were selected as 1 and 2 for determination of nitazoxanide and 294.3 nm and 388.1 nm were selected as 3 and 4 for determination of ofloxacin. Both drugs obeyed the Beer's law in the concentration range 2-30 μg/ml,correlation coefficient (r(2)<1). Both methods were validated statistically and recovery studies were carried out to confirm the accuracy. Commercial tablet formulation was successfully analyzed using the developed methods.