Abstract
QuEChERS (quick, easy, cheap, effective, rugged and safe) dispersive extraction was applied for the extraction of tetracyclines (oxytetracycline, tetracycline, chlorotetracycline and doxycycline) from milk. Target analytes were determined by an accurate and sensitive chromatographic analytical method, which was validated in terms of 2002/6572/EC decision. The analytes were separated on an Orbit 100C4 (5 μm, 250 × 4.0 mm) analytical column under a gradient mobile phase composed of a mixture of 0.01 M oxalic acid, 10−4 M Na2EDTA and acetonitrile. For the extraction of isolated compounds from sorbent, a methanol and 0.01 M oxalic acid mixture (1:1 v/v) was used, leading to relative recovery rates from 83.07% to 106.3% at concentration levels in the range 100–200 μg/kg. The within-laboratory reproducibility, expressed as a relative standard deviation, was <15.5%. Decision limits ranged between 100.3 μg/kg and 105.6 μg/kg and the detection capability varied between 100.6 μg/kg and 109.7 μg/kg. Ruggedness was evaluated by following the Youden approach, in terms of milk mass, sorbent mass, centrifugation time, vortex time, type and volume of organic solvents and evaporation temperature.
Highlights
Tetracyclines belong to the broad-spectrum antibiotics that are active against both gram-positive and gram-negative bacteria
Many sample preparation strategies have been developed for the isolation and clean-up of tetracycline residues in milk throughout the years, such as solid phase extraction (SPE) with various types of sorbents [4,5], solid phase microextraction (SPME) [6], hollow-fiber liquid phase microextraction (HF-LPME) [7] and ultrasound assisted dispersive extraction [8]
Quantitative analysis was performed on a HPLC system with a diode array detector (355 nm)
Summary
Tetracyclines belong to the broad-spectrum antibiotics that are active against both gram-positive and gram-negative bacteria. They are commonly used in veterinary medicine for the prevention and treatment of several infectious diseases or as feed additives to promote growth in farm animals [1]. Modern sample preparation techniques focus on the reduction of organic solvent consumption in less time. These include QuEChERS (acronym name for quick, easy, cheap, effective, rugged and safe) methodology, which was introduced in 2003 by Anastassiades et al [9] Target analytes are extracted by acetonitrile, followed by an included liquid-liquid partition after the addition of salts and a dispersive
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