Detection of azithromycin residue in broiler feathers by liquid chromatography-tandem mass spectrometry.

In the study, a sensitive and reproducible method for the quantitative analysis of azithromycin in broiler feather samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. Feather samples were rinsed after being wrapped in medical gauze, then chopped and then added to 5% (v/v) ammonia in methanol solution for ultrasonic extraction. The extract was purified by the combination of commercial polymeric microparticles (Oasis MCX) and Fe3O4 nanoparticles. The LC separation was performed on an Agilent Eclipse plus C18 column. Multiple reaction monitoring was used for the selective detection of azithromycin. The good linearity curve of azithromycin in feather sample was in the range from 1.0 µg kg-1 to 100.0 µg kg-1 with 0.9935 of correlation coefficient. And the limit detection and limit of quantification was 0.5 µg kg-1 and 2.0 µg kg-1 in spiked feather samples. The recoveries of azithromycin were 85.2-94.7% with the relative standard deviation less than 10%. The established method is simple, rapid, sensitive and specific, and could meet the need of government and enterprises to monitor the illegal use of azithromycin in livestock and poultry breeding.

Carbamoylated azithromycin incorporated zirconia hybrid monolith for enantioseparation of acidic chiral drugs using non-aqueous capillary electrochromatography.

Carbamoylated derivatives of two antibiotics, namely, clindamycin phosphate (CLIP) and erythromycin (ERY) were successfully employed as co-precursors, in combination of zirconium tetrabutoxide as a precursor, to prepare chiral organic-zirconia hybrid monoliths (i.e., CLIP-ZHMs and ERY-ZHMs, respectively) via a single-step in-situ sol-gel approach in our previous works. Their superiority over chiral organic-zirconia/silica monoliths, prepared by post-modification approach, in terms of better enantioresolution and enhanced stability inspired us to prepare ZHMs based on an another antibiotic, azithromycin (i.e., AZI-ZHMs). Monolithic columns were employed for capillary electrochromatographic enantioseparation of acidic chiral drugs in mobile phases consisting of acetonitrile (ACN) and methanol (MeOH) as organic modifiers, and acetic acid (AcOH) and triethylamine (TEA) as electrolytes. The effects of composition of mobile phase and applied voltage on chiral separation were investigated by using ketoprofen as a representative analyte. Baseline resolutions were obtained for six acidic drugs in mobile phase consisting of 80/20 (v/v) ACN/MeOH with 300mM AcOH and 10mM TEA at a 10kV applied voltage and 25°C capillary temperature. The relative standard deviations for resolution values regarding column to column and batch to batch repeatability were less than 2.5% (for n=3) under optimized conditions, indicating satisfactory stability of the columns and reproducibility of the column preparation process.

An optimal LC-MS/MS method for determination of azithromycin in white blood cells: application to pediatric samples.

BACKGROUND: Studies suggest that particular antimicrobial and anti-inflammatory properties of azithromycin (AZM) can be related to its extensive accumulation in white blood cells (WBCs). However, available methods for determination of AZM in WBCs require large blood volumes unsuited to a pediatric context. Therefore, an LC-MS/MS method was developed for determination of AZM in WBCs. RESULTS: WBCs were isolated from 500 µl of whole blood by lysing red blood cells. Then, lysis of WBCs was performed with methanol/buffer containing AZM-d3-(13)C as internal standard. After reversed phase LC, detection was performed under multiple reaction monitoring conditions in positive electrospray mode. Linearity ranged from 0.5 to 200 ng per WBC sample. Within-run and overall accuracy and precision ranged from 95.3 to 101.1% and from 1.6 to 4.7%, respectively. All validation parameters fulfilled international requirements. CONCLUSIONS: This method can be easily performed on small samples and provides reliable data, including in children and neonates.

A concise review of HPLC, LC-MS and LC-MS/MS methods for determination of azithromycin in various biological matrices.

Azithromycin is one of the best selling antibiotics in the world. It belongs to the new macrolide family of azalides. It is derived from erythromycin and it differs from erythromycin in having a 15-membered ring and a methyl substituted nitrogen inserted at the 9a position in the aglycone ring. This structural modification confers favourable microbiological and pharmacokinetic characteristics on azithromycin and greater acid stability compared with erythromycin. It is mainly used to treat respiratory infections, sexually transmitted diseases, cutaneous and soft-tissue infections, etc. This review provides a comprehensive overview of various HPLC, LC-MS and LC-MS/MS methods for quantitation of azithromycin in different biological matrices. In addition, it provides general information on extraction steps, internal standard selection, conditions for chromatographic separation, brief validation data and applicable conclusions for reported methods in a defined pattern.

Quantitative determination of azithromycin in human plasma by ultra performance liquid chromatography-electrospray ionization mass spectrometry and its application in a pharmacokinetic study.

A selective, rapid and sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the quantitative determination of azithromycin in human plasma and its application in a pharmacokinetic study. With roxithromycin as internal standard, sample pretreatment involved a one-step extraction with diethyl ether of 0.5 mL plasma. The analysis was carried out on an ACQUITY UPLC BEH C(18) column (50 mm x 2.1 mm, i.d., 1.7 microm) with gradient elution at flow rate of 0.35 mL/min. The mobile phase was 50 mM ammonium acetate and acetonitrile. The detection was performed on a triple-quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode via electrospray ionization (ESI). Linear calibration curves were obtained in the concentration range of 1-1000 ng/mL, with a lower limit of quantification of 1 ng/mL. The intra- and inter-day precision (RSD) values were below 15% and accuracy (RE) was -1.3% to 5.7% at all QC levels. The method was applicable to clinical pharmacokinetic study of azithromycin in healthy volunteers following oral administration.

Azithromycin extraction from municipal wastewater and quantitation using liquid chromatography/mass spectrometry.

Azithromycin is a broad spectrum antimicrobial agent that is approved in the United States for use in humans. Due to azithromycin's low rate of metabolism it is likely to be found in wastewater treatment plants, where its broad spectrum of antimicrobial activity could lead to development of resistance in bacteria. A liquid-liquid extraction using K2CO3 and methyl-t-butyl ether (MTBE) was used to extract azithromycin from 10 ml aliquots of wastewater. Liquid chromatography was performed using a Luna C18(2) (30 mm x 2.0 mm) column with a mass spectrometer friendly mobile phase containing 50:24:2:24 acetonitrile, methanol, tetrahydrofuran, and 0.04 M ammonium hydroxide. The mass spectrometer used an electrospray source with positive ionization and an ion trap detector. A linear standard curve from 5 to 200pg/ml was validated and used to quantitate azithromycin in wastewater.