Determination Of Tetracyclines In Milk Research Articles

Evolution of a natural TetR protein and development of a Fe3O4 assisted semi-homogeneous fluorescent method for determination of tetracyclines in milk

Compared with antibody, the recognition spectrum of a receptor is broader, and its recognition ability can be improved using simple mutagenesis technique. Compared with conventional immunoassay, the magnetic bead based immunoassay is simpler and can be recycled. Compared with colorimetric and luminescent immunoassays, fluoroimmunoassay is simpler because it does not require a substrate. So a method combines these merits is desirable. In this study, two amino acids in the binding pocket of a natural Escherichia coli TetR protein were mutated to produce a mutant, and the molecular docking showed the binding energies and the numbers of contact acid for 10 tetracyclines all increased. The mutant was coupled with Fe3O4 to synthesize a magnetic complex, and a fluorescent tracer was synthesized by coupling quantum dot and minocycline with bovine serum albumin. Under the assistance of 96-well bottom magnet, a semi-homogeneous method based on the two materials was developed on conventional microplate for determination of the 10 tetracyclines in milk. Results showed once assay was finished within 20 min, the limits of detection (drug concentration showing 10% inhibition) for the 10 drugs were in the range of 0.32–0.94 ng/mL, and the magnetic complex could be regenerated for 6 times. Furthermore, the sensitivities were improved for 4–6 folds in comparison with the use of natural TetR. Therefore, this method is simple, sensitive, time-saving and recyclable, and it can be used for routine screening of the 10 tetracyclines in milk.

Sensitive and selective determination of tetracycline in milk based on sulfur quantum dot probes.

A novel fluorescent probe based on sulfur quantum dots (SQDs) was fabricated for sensitive and selective detection of tetracycline (TC) in milk samples. The blue emitting SQDs were synthesized via a top–down method with assistance of H2O2. The synthesized SQDs showed excellent monodispersity, water solubility and fluorescence stability, with a quantum yield (QY) of 6.30%. Furthermore, the blue fluorescence of the obtained SQDs could be effectively quenched in the presence of TC through the static quenching effect (SQE) and inner filter effect (IFE) between TC and SQDs. Under the optimum conditions, a rapid detection of TC could be accomplished within 1 min and a wide linear range could be obtained from 0.1 to 50.0 μM with a limit of detection (LOD) of 28.0 nM at a signal-to-noise ratio of 3. Finally, the SQD-based fluorescent probe was successfully applied for TC determination in milk samples with satisfactory recovery and good relative standard deviation (RSD). These results indicate that the SQD-based fluorescent probe shows great potential in practical analysis of TC in real samples with high rapidity, selectivity, and sensitivity.

A synergistic effect of hydrophobic deep eutectic solvents based on terpenoids and carboxylic acids for tetracycline microextraction.

Hydrophobic deep eutectic solvents were investigated for tetracycline microextraction. It was found that a deep eutectic solvent consisting of thymol and octanoic acid provided a synergistic effect on tetracycline extraction. In this paper, a novel liquid-liquid microextraction procedure for the HPLC-DAD determination of tetracyclines in milk samples was proposed.

A highly sensitive tetracycline sensor based on a combination of magnetic molecularly imprinted polymer nanoparticles and surface plasmon resonance detection.

A method is reported for in-situ detection of the antibiotic tetracycline (TC). It is based on a combination of extraction of TC by magnetic molecularly imprinted polymers nanoparticles (MMIPs NPs) and detection by surface plasmon resonance (SPR). The TC-captured MMIPs NPs were flowed over the surface of the SPR chip that was modified with mercaptoethylamine. The SPR signal undergoes a strong increase through the use of MMIPs NPs. It increases linearly in the 5.0-100pg·mL-1 TC concentration range, and the detection limit is as low as 1.0pg·mL-1 (at S/N = 3). This method shows selectivity to TC compared with structurally analogues. In order to demonstrate the power of the method, it was applied to the analysis of milk spiked with TC. These results were validated by comparing them to those of an enzyme-linked immunoassay. The average recovery is in the range of 95.7-104.6%. Graphical abstract Schematic representation of a surface plasmon resonance assay for the sensitive determination of tetracycline in milk using the magnetic molecularly imprinted polymers nanoparticles that can extract tetracycline and amplify the SPR signal.

High-throughput amperometric determination of tetracycline residues in milk and quality control of pharmaceutical formulations: flow-injection versus batch-injection analysis

This paper demonstrates a potential use of the reduced graphene-oxide modified electrode associated with FIA and BIA systems for rapid, simple and sensitive determination of tetracycline in milk and pharmaceutical formulations samples.

ИСПОЛЬЗОВАНИЕ ЭЛЕКТРОДА, МОДИФИЦИРОВАННОГО ПОЛИВИНИЛПИРРОЛИДОНОВОЙ ПЛЕНКОЙ С ВКЛЮЧЕННЫМ ОСАДКОМ ЗОЛОТА, ДЛЯ ВОЛЬТАМПЕРОМЕТРИЧЕСКОГО ОПРЕДЕЛЕНИЯ ТЕТРАЦИКЛИНА В МОЛОКЕ

ИСПОЛЬЗОВАНИЕ ЭЛЕКТРОДА, МОДИФИЦИРОВАННОГО ПОЛИВИНИЛПИРРОЛИДОНОВОЙ ПЛЕНКОЙ С ВКЛЮЧЕННЫМ ОСАДКОМ ЗОЛОТА, ДЛЯ ВОЛЬТАМПЕРОМЕТРИЧЕСКОГО ОПРЕДЕЛЕНИЯ ТЕТРАЦИКЛИНА В МОЛОКЕ

A receptor-based chemiluminescence enzyme linked immunosorbent assay for determination of tetracyclines in milk

This study for the first time reported a receptor based chemiluminescence immunoassay for analysis of tetracyclines. During the experiments, the gene of TetR protein was transformed into Rosetta-gami(DE3) to express a receptor, and its recognition mechanism for 5 tetracyclines was studied by using molecular docking technique. Results showed that hydrophobic interaction and Pi-Pi bond were the main intermolecular forces responsible for TetR-tetracyclines binding, and the D ring was the main receptor binding position in tetracyclines molecules. Then the receptor was used as recognition reagent to develop a direct competitive enzyme linked immunosorbent assay for determination of the 5 drugs in milk, and the light signal was induced with 4-(imidazol-1-yl)phenol enhanced luminol-H2O2 system. The limits of detection for the 5 drugs in milk were in the range of 5–16 pg/mL, and the recoveries from the standards fortified blank milk were in the range of 71.7%–95.8%. Therefore, this method could be used as a simple, rapid, and ultra-sensitive tool to monitor the residues of tetracyclines in milk.

Determination of Tetracyclines in Milk, Eggs and Honey Using in-situ Ionic Liquid Based Dispersive Liquid–Liquid Microextraction

In this study, in-situ ionic liquid based dispersive liquid−liquid microextraction method for enrichment of tetracyclines before liquid chromatographic analysis has been improved. A 1-benzyl-3- methylimidazolium chloride was used as an ionic liquid. To increase extraction efficiency, some optimization parameters (amount of ammonium hexafluorophoshate, extraction time, centrifugation time, ratio of ionic liquid/salt) were investigated. At optimized conditions, enrichment factors of four tetracycline antibiotics (tetracycline, chlortetracycline, methacycline, doxycycline) were between 25 and 98. The residues of tetracyclines were not found in the studied real samples. For the accuracy of the method, the concentration of 50 and 250 μg/L of standard tetracycline mixture solutions were spiked to the blank real milk, honey and egg samples and the percentage recoveries were obtained in the range of 75.8–109.7%.

Determination of Tetracyclines in Milk by Graphene-Based Solid-Phase Extraction and High-Performance Liquid Chromatography

ABSTRACTA graphene-based solid-phase extraction (SPE) column was prepared for the isolation of tetracyclines from milk followed by determination by high-performance liquid chromatography. Graphene provided better separation for tetracyclines than amine-modified graphene and carboxyl-modified graphene. The optimized graphene-based SPE column showed high absorption capacities (greater than 4,660 ng) and high recoveries (exceeding 92%) for tetracycline, oxytetracycline, chlortetracycline, and doxycycline and was successfully reused at least fifty times. The limits of detection in milk were from 10 to 20 ng/mL, with recoveries between 82.3 and 103.6%. Furthermore, the system showed superior performance than two commercial SPE cartridges with respect to recovery, purification, and reusability. Therefore, this approach is suitable for the determination of tetracyclines in milk.

Ultrasound-assisted surfactant/ionic liquid aqueous two-phase system extraction prior to high performance liquid chromatography for the determination of tetracyclines in milk and honey samples

In this work, an ultrasonic-assisted surfactant/ionic liquid aqueous two-phase system (ATPS) extraction method was developed to extract six tetracycline antibiotics from food samples before their chromatographic determination using high performance liquid chromatography. The ATPS was formed with 1-allyl-3-methyl-imidazolium bromide, Triton X-100, and dipotassium hydrogen phosphate. The parameters including type and amount of surfactant, ionic liquid and salt, pH of sample solution, and sonication time were optimized. Under the optimized conditions, linear calibration curves of the six tetracyclines were obtained in the range of 10--500 $\mu $g L$^{-1}$ with $>$ r$^{2} =$ 0.990 (n $=$ 9). The proposed green analytical extraction method was applied to the analysis of tetracycline antibiotics in milk and honey samples with recovery of 50%--110% and 68%--117%, respectively.

HPLC determination of tetracycline antibiotics in milk with post-column derivatization and fluorescence detection

The conditions for sensitive and selective determination of tetracyclines in milk in the form of their complexes with Mg2+ via the HPLC method with post-column derivatization and fluorescence detection are found. It is shown that the fluorescence of tetracycline-Mg2+ complexes in microemulsions is 1.8 times more intense than that in aqueous acetonitrile medium. The detection limits of tetracycline, oxytetracycline, and doxycycline are 5, 8 and 25 ng mL–1, respectively.

Determination of tetracyclines by novel singlet-oxygen mediated cerium(IV) chemiluminescence

ABSTRACTNovel chemiluminescence mechanisms of cerium(IV) and five tetracyclines in the absence and presence of Tween 80 are reported. The role of tetracyclines in the present chemiluminescence system was studied in detail by ultraviolet spectra and the singlet oxygen 1O2 probe 2-methyl-6-(4-methoxyphenyl)-3, 7-dihydroimidazo[1,2-a]-pyrazin-3-one hydrochloride. It is the first report that cerium(IV) reacted with tetracyclines producing singlet oxygen 1O2 after breaking the organic skeleton and decomposition of peroxyacetic acid in the absence of the surfactant Tween. Furthermore, by examining the effects of sodium azide and the chemiluminescence spectra, the results indicated that the maximum chemiluminescence emission at approximately 480 nm was due to dimer emission of singlet oxygen 1O2 from the reaction between cerium(IV) and tetracyclines as well as the reaction of cerium(IV) and Tween 80, respectively. Moreover, the chemiluminescence signals were unaffected when the reaction was performed under anaerobic condition, indicating that dissolved oxygen was independent of this system. Under the optimal conditions, the analytical characteristics and parameters of the cerium(IV)-Tween 80-tetracyclines chemiluminescence system were investigated. The present method was successfully employed for the determination of tetracyclines in milk.

Экспресс-определение тетрациклинов в молоке методом масс-спектрометрии высокого разрешения

Экспресс-определение тетрациклинов в молоке методом масс-спектрометрии высокого разрешения

Sorption and chromatographic determination of tetracycline in milk and dairy products

The sorption of tetracycline on natural zeolite is studied: the optimum process conditions, distribution coefficient, and sorption capacity were determined. A method for determining this antibiotic in milk and dairy products is proposed, based on the preliminary sorption concentration of tetracycline on zeolite followed by analyte determination by HPLC with UV detection. The advantages of this procedure are the low cost [ARC1]of analysis, and the simplicity and rapidity of execution. The procedure can be used in the practice of laboratories performing chemical analysis of foodstuffs.

Determination of tetracycline in milk by using nucleotide/lanthanide coordination polymer-based ternary complex

The meta-organic coordination polymers have been emerged as fascinating nanomaterials because of their tunable nature. In this work, we employed lanthanide coordination polymer self-assembled from adenosine monophosphate (AMP) and europium ion (Eu3+) as receptor reagent and citrate (Cit) as ancillary ligand to construct a fluorescent sensor for the detection of tetracycline (Tc) in milk. The co-coordination of Cit and Tc with Eu3+ on the surface of the coordination polymer AMP/Eu leads to the formation of ternary complex which emitted strong fluorescence due to the removal of coordinated water molecules and an intramolecular energy transfer from Tc to Eu3+. The fluorescent intensity of Eu3+ displayed a good linear response to Tc concentrations in the range of 0.1–20μM with a detection limit of 60nM. This method was successfully applied to determine the levels of Tc in milk, which is the first application of coordination polymer as a fluorescent sensor in real sample. Compared with other Eu3+-based fluorescent methods for Tc detection, the presented method allows simple, direct analysis of Tc without requiring special reaction media or complicated prepreparation processes. This straightforward strategy could be extended to the preparation of other lanthanide coordination polymer-based fluorescent probes for applications in biosensing, imaging, drug delivery, and so on.

Study of robustness based on n-way models in the spectrofluorimetric determination of tetracyclines in milk when quenching exists

An important step in the validation of an analytical procedure is the study of its robustness. In the case of spectrofluorimetric determinations, quenching introduces specific problems which are approached in this paper for the particular case of tetracyclines determination in milk. Quenching can be detected with excitation emission matrices (EEM) signals and a three-way Parallel Factor (PARAFAC) decomposition and modelled by means of a four-way PARAFAC decomposition which reproduces the physical model of this effect. The robustness of the method is evaluated by including changes in seven experimental variables: trichloroacetic acid (TCA) volume solution used in the precipitation of milk proteins, revolutions per minute, time and temperature in the centrifugation step, pH and emission-excitation slit width in the fluorimetric analyte determination and the analyst. The robustness analysis is carried out by means of a Plackett-Burman experimental design as it is suggested by European Decision 2002/657/EC (European Decision (EC) No. 2002/657/EC of 12 August 2002, implementing Council Directive 96/23/EC, concerning the performance of analytical methods and the interpretation of results, Off. J.L 221, 17/8/2002, 8). The analyte concentration will be taken as response in the Plackett-Burman experimental design instead of the signal as it is habitual in these cases. Therefore, a three-way Partial Least Squares (3-PLS) calibration models with EEM signal is needed. When an analogous study is carried out for tetracycline (TC) in the absence of chlorotetracycline (CTC) as interferent, univariate calibration is employed, being able to conclude that in the robustness analysis, different factors are significantly active when quenching exists.

Biotin–avidin mediated competitive enzyme-linked immunosorbent assay to detect residues of tetracyclines in milk

Tetracycline (TC) antibiotics are widely used for prevention and control of disease because they inhibit the growth of bacteria. However, the presence of TC antibiotics residues in food causes harmful effects on consumer's health such as allergic reactions, liver damage and gastrointestinal disturbance, so that many countries have set MRLs (maximum residue levels). Therefore, it is necessary to detect tetracycline residues, to develop suitable analytical techniques to be used as routine screens and field detection. A new approach to the biotin–avidin mediated competitive ELISA is developed to determine tetracycline residues in milk. After optimization, the LOD and LOQ were 1.0 × 10 − 10 M (0.048 μg/L) and 1.0 × 10 − 9 M, respectively, and the working range from 3.16 × 10 − 10 M to 3.16 × 10 − 7 M toward TC in milk. No cross-reactivity was observed with the structurally similar compounds; chlortetracycline (13.7%), oxytetracycline (10%) and doxytetracycline (< 1%). Additionally percent recoveries of TC spiked in milk were quite satisfactory (∼ 90%). Comparing our results obtained in this work with others, it shows with the capability to detect TC ranging in MRLs (100 μg/L in milk) sufficiently with highly sensitivity in milk, and with simple pre-treatment. In addition, this method can apply to developing useful ELISA test kit for determination of TCs in milk.

Rapid Determination of Tetracycline in Milk by FT-MIR and FT-NIR Spectroscopy

The feasibility of measuring tetracycline at the ppb levels in milk was investigated by Fourier transform mid-infrared (FT-MIR) and Fourier transform near-infrared (FT-NIR) spectroscopic techniques. Milk samples spiked with different concentrations of tetracycline were scanned using FT-MIR and FT-NIR spectroscopy. Suitable spectral wave number regions were selected for principal least square (PLS) regression models development. Prediction errors were high when the calibration model was developed using the wide range of tetracycline concentrations (4 to 2000 ppb) in milk. Maximum correlation coefficient (R2) value of about 0.89 was obtained for the validation models developed using different concentration ranges. Prediction errors were high for FT-NIR method. Results indicated that FT-MIR spectroscopy could be used for rapid detection of tetracycline hydrochloride residues in milk.