HPLC-DAD and LC-ESI-MS analysis of doxycycline and related impurities in doxipan mix, a medicated premix for incorporation in medicated feedstuff

Quantitative determination of tetracyclines in medicated feed for food-producing animals by HPLC-DAD

Tetracyclines are a group of antibiotic substances largely administered through medicated feed to control diseases in food-producing animals. Fine dosing of antibiotics contained in medicated feed is crucial for the success of the treatment as well as minimising potential threats such as the spread of antimicrobial resistance and the transfer of antibiotic residues in food. A rapid analytical method based on HPLC with diode array detection (HPLC-DAD) was developed to quantify oxytetracycline, chlortetracycline and doxycycline in medicated feed. The reported method underwent in-house validation and was found to be suitable for the quantification of three target tetracyclines within the concentration range of 40-1000 mg kg-1 in official routine analysis. The method was applied to 103 official samples in the framework of the Italian National Plan on animal feed during the years 2021-2023 and nine non-compliant concentrations were identified in swine and fish feed samples.

All-in-one coupling of 3D hybridized nanocarbon microelectrode for portable monitoring of doxycycline hyclate

The simultaneous balance of electrode materials and electrode structures can energize the development of innovative electrochemical sensors. In this work, a 3D nanocarbon layer of hybrid heteroatoms and metal atoms (CN/Fe) with excellent electrical properties and abundant active sites was self-constructed on the surface of a quartz-based nanofiber by high-temperature pyrolysis. Further, the nanofiber tip was selected as the sensing region to develop an electrochemical sensing platform with high sensitivity, miniaturization, and portability. A common broad-spectrum antibiotic (Doxycycline hyclate, DOX) was used as a model to evaluate the designed miniaturized sensing platform, and the stability, reproducibility, and applicability of the microsensor were verified in a variety of real samples, including algal solution, milk, human serum, and cell culture media. The results show that the proposed sensing platform has a detection limit as low as 82 nM in aqueous environments. Furthermore, it is further shown that coupling the design of electrode materials and electrode structures facilitates the development of electrochemical sensors with more practical applications. This concept will open up new avenues for the development of electrochemical sensors that meet many application scenarios.

High performance thin layer chromatography (HPTLC) method development and validation for determination of doxycycline hyclate in capsule and tablet formulations

According to World Health Organization (WHO) 10% of the medicines in the Low and Middle Income Countries (LMICs) are of poor quality posing a major public health threat. One way to circumvent such problem is the development and deployment of rapid, economical and efficient analytical methods. Hence this research aims to develop a High-Performance Thin Layer Chromatography (HPTLC) method for the determination of doxycycline hyclate. A rapid and simple HPTLC method with densitometry detection at 360 nm to determine doxycycline hyclate in capsules and tablet formulations was developed and validated. HPTLC was performed on glass plates coated with C18 reverse phase silica gel 60 F254 and pretreated with 0.27 M ethylenediaminetetraaceticacid (EDTA) solution. The mobile phase was dichloromethane: methanol: acetonitrile: 1% aqueous ammonia in the ratio of 10:22:53:15 (v/v). The linearity range lies between 200 and 1,000 ng/spot with correlation coefficient of 0.997. The Rf value is 0.5 ± 0.02%. Recoveries were in the range of 94.50–100.5%. Limit of detection and limit of quantitation values for doxycycline hyclate were 40 and 160 ng/spot respectively. The developed method was validated as per ICH guidelines. Thus, it was found to be accurate, precise, specific and robust. In forced degradation study, doxycycline hyclate was found to degrade in acidic and alkaline media, and through oxidative stress. The drug was found to be relatively stable to heat and photo degradation. The method was successfully applied for the routine quantitative analysis of dosage forms containing doxycycline hyclate. The developed method offered comparable results (as confirmed by F-test) with that of the HPLC pharmacopoeial (BP) analysis method.

Comparison of HPLC–DAD and LC–MS Techniques for the Determination of Tetracyclines in Medicated Feeds Using One Extraction Protocol

Four antibiotics, oxytetracycline, tetracycline, doxycycline, and chlortetracycline were separated and quantified in medicated feed. Tetracyclines from feed samples were extracted with 0.01 M citric buffer and acetonitrile (pH 3.0) and further purified with 0.45 µm syringe filters. The purified extract was separated on commercial RP-C18 column and analyzing using liquid chromatograph (LC) with two different detectors: diode array detector (DAD) and mass spectrometry (MS). These methods provided average recoveries from 72.2 to 101.8% for high pressure liquid chromatography (HPLC) with diode array detection and from 45.6 to 87.0% for liquid chromatography with mass spectrometry. The limit of detection in medicated feed ranged from 4.2 to 10.7 mg kg−1 for HPLC–DAD and 5.6 to 10.8 mg kg−1 for LC–MS. Our experiment showed that using the same extraction mixture we do not obtain the same recovery values for the analyzed compounds using two different detection techniques such as DAD and MS.

A novel fluorescent sensor based on sulfur and nitrogen co-doped carbon dots with excellent stability for selective detection of doxycycline in raw milk

Sulfur and nitrogen co-doped carbon dots obtained from casein exhibited excellent sensitivity and selectivity for the detection of doxycycline.

Development and validation method for the determination of selected tetracyclines in animal medicated feedingstuffs with the use of micellar liquid chromatography

A chromatographic procedure for the determination of oxytetracycline (OTC), tetracycline (TC), chlorotetracycline (CTC), and doxycycline (DC) in medicated feedingstuffs was developed. Samples were extracted with 0.01 M citric buffer/acetonitrile (pH 3.0) and further purified with 0.45 μm syringe filters. The purified extract was separated on Thermo column C18, 150 × 4 mm, 5 μm and detection was carried out at 360 nm for OTC, and TC, 370 nm for CTC, and 350 nm for DC. TCs were eluted with a mobile phase of 0.03 M SDS/7% 1-butanol/0.02 M oxalic acid/NaOH at pH 2.5. This method provided average recoveries of 80.4% to 100.2%, with CVs of 0.5% to 6.6% in the range of 50 to 1500 mg/kg OTC, TC, CTC, and DC in feeds. The linearity for the four TCs was determined by high-performance liquid chromatography-diode array detector (HPLC-DAD) in the range 10-300 μg/mL (50-1500 mg/kg), with a linear correlation coefficient (R) > 0.99. The LOD and LOQ for TCs in pig and poultry feeds ranged from 4.0 to 10.7 and 4.7 to 12.6 mg/kg, respectively. The methodology was applied to the analysis of animal feedingstuffs collected from poultry and pig farms.

Quantification of doxycycline hyclate in tablets by HPLC-UV method

An accurate, sensitive, precise and rapid gradient reversed-phase high-performance liquid chromatographic method was successfully developed and validated for the determination of doxycycline hyclate in bulk drug and tablets. The best separation was achieved on a 250 × 4.6 mm, 5.0 µm particle size CN Luna column with water + 0.1% TFA-acetonitrile + 0.1% TFA, 60:40 (v/v) as the mobile phase at a flow rate of 1.0 mL/min. Ultraviolet detection was performed at 360 nm at ambient column temperature (25°C). The method was linear over the concentration range of 50-100 µg/mL (r = 0.9999) with limits of detection and quantification of 2.83 and 8.59 µg/mL, respectively. The drug was subjected to oxidation, acid, base and neutral degradation, photolysis and heat as stress conditions. Degradation products were found interfering with the assay of doxycycline hyclate, therefore the method can be regarded as suitable. The method was applied for the determination of doxycycline hyclate in standard and pharmaceutical products, with excellent recoveries. The method can be used for the quality control of doxycycline hyclate.

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.

HPLC and chemometrics-assisted UV-spectroscopy methods for the simultaneous determination of ambroxol and doxycycline in capsule

High-performance liquid chromatography (HPLC) and multivariate spectrophotometric methods are described for the simultaneous determination of ambroxol hydrochloride (AM) and doxycycline (DX) in combined pharmaceutical capsules. The chromatographic separation was achieved on reversed-phase C(18) analytical column with a mobile phase consisting of a mixture of 20mM potassium dihydrogen phosphate, pH 6-acetonitrile in ratio of (1:1, v/v) and UV detection at 245 nm. Also, the resolution has been accomplished by using numerical spectrophotometric methods as classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS-1) applied to the UV spectra of the mixture and graphical spectrophotometric method as first derivative of the ratio spectra ((1)DD) method. Analytical figures of merit (FOM), such as sensitivity, selectivity, analytical sensitivity, limit of quantitation and limit of detection were determined for CLS, PLS-1 and PCR methods. The proposed methods were validated and successfully applied for the analysis of pharmaceutical formulation and laboratory-prepared mixtures containing the two component combination.

Determination of doxycycline in pharmaceuticals and human urine by micellar electrokinetic capillary chromatography

Micellar electrokinetic capillary chromatography (MEKC) was performed at 25 degrees C and 30 kV (under a pressure of 15 mbar), using 30 mM borate buffer containing 60 mM sodium dodecysulfate (SDS) and 5% (v/v) methanol as background electrolyte (pH 9.0) to determine doxycycline. UV detection was at 350 nm. The method was shown to be specific, accurate (recovery was 100.3 +/- 1.0%), linear over the tested range (correlation coefficient 0.9995) and precise (RSD <1.9%). The method was used to determine doxycycline in tablets, capsules and human urine after oral application.