Solid-Phase Extraction and Large-Volume Sample Stacking-Capillary Electrophoresis for Determination of Tetracycline Residues in Milk

Abstract

Solid-phase extraction in combination with large-volume sample stacking-capillary electrophoresis (SPE-LVSS-CE) was applied to measure chlortetracycline, doxycycline, oxytetracycline, and tetracycline in milk samples. Under optimal conditions, the proposed method had a linear range of 29 to 200 µg·L−1, with limits of detection ranging from 18.6 to 23.8 µg·L−1 with inter- and intraday repeatabilities < 10% (as a relative standard deviation) in all cases. The enrichment factors obtained were from 50.33 to 70.85 for all the TCs compared with a conventional capillary zone electrophoresis (CZE). This method is adequate to analyze tetracyclines below the most restrictive established maximum residue limits. The proposed method was employed in the analysis of 15 milk samples from different brands. Two of the tested samples were positive for the presence of oxytetracycline with concentrations of 95 and 126 µg·L−1. SPE-LVSS-CE is a robust, easy, and efficient strategy for online preconcentration of tetracycline residues in complex matrices.

Advances in the Analysis of Veterinary Drug Residues in Food Matrices by Capillary Electrophoresis Techniques

“…Islas et al recently set-up a SPE step followed by a large-volume sample stacking (LVSS) approach before a CZE-UV analysis of TC. LVSS consisted of a stacking procedure with an on-line series of polarity switches (PS) and enabled an improvement in sensitivity and reproducibility, particularly useful for low-concentration analytes in complex matrices, such as milk samples (Figure 1) [62]. The same pre-concentration approach (SPE-LVSS-PS) was previously used to determine five TC residues (metacycline-MTC, OTC, TC, CTC, and DC) in water samples, reaching a high sensitivity (ng/L) in a short time (10 min) [63].…”

“…Solid phase extraction (SPE)-large-volume sample stacking (LVSS)-capillary electrophoresis (CE) method applied to milk sample for the detection of tetracyclines (TCs). Electropherograms of (a) standard TC sample (10 mg/L) analyzed by CE, (b) standard TC sample (1 mg/L) analyzed by LVSS-CE, (c) blank milk sample, and (d) real milk sample analyzed by SPE-LVSS-CE method[62].…”

Recent progress of sample stacking in capillary electrophoresis (2016–2018)

“…SPE in combination with LVSS‐CE was used by Islas et al. to analyze chlortetracycline, doxycycline, oxytetracycline and tetracycline in milk. The BGE consisted of 30 mM sodium phosphate, 2 mM Na 2 EDTA, NaOH and 2% 2‐propanol at pH 12.0.…”

Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2016–2018)

“…Fundamental to this approach is that the electrophoretic mobilities of the analytes must be opposite to that of the EOF. LVSS with polarity switching has been broadly used for highly sensitive analysis of a wide variety of analytes including antibiotics (e.g., chlortetracycline, doxycycline, oxytetracycline, and tetracycline) in milk and environmental water samples ; camptothecin alkaloids (e.g., Camptothecin, 9‐methoxycamptothecin, 9‐aminocamptothecin, 10‐hydroxy‐camptothecin, and 7‐ethyl‐10‐hydroxycamptothecin), a potential antitumor drug isolated from the bark and fruit of a Chinese tree ; active ingredients (rutin, hyperoside, and chlorogenic acid) in herbal medicine ; and food‐borne pathogen, Salmonella typhimurium in water samples. Although LVSS with polarity switching is very popular, meticulous current monitoring makes automation of LVSS using commercial CE system a challenging task.…”