Sensitive determination of four tetracycline antibiotics in pig plasma by field-amplified sample stacking open-tubular capillary electrochromatography with dimethylethanolamine aminated polychloromethyl styrene nano-latex coated capillary column

• A new dimethylethanolamine amination polychloromethyl styrene nano-latex (DMEAPL) was synthesized.
• DMEAPL coated capillary column (ccc-DMEAPL) was prepared and it provided the steady EOF within acidic pH range.
• Sensitive determination of tetracycline antibiotics (TCs) in pig plasma were developed by field-amplified sample stacking OT-CEC with ccc-DMEAPL.

This paper described the preparation and application of a new dimethylethanolamine aminated polychloromethyl styrene nano-latex (DMEAPL) coated capillary column (ccc-DMEAPL) in the determination of four tetracycline antibiotics (TCA) including tetracycline (TC), oxytetracycline (OTC), doxycycline (DC) and chlorotetracycline (CTC) in pig plasma. The ccc-DMEAPL column was characterized with steady EOF values of ca. 1.5–5.2 × 10−5 cm2/V s at pH 1.8–6.3. The optimized conditions for field-amplified sample stacking open-tubular capillary electrochromatography (FASS-OT-CEC) were as following: background electrolyte, 10 mmol/L Na2HPO4 + 15 mmol/L citric acid (pH 3.2); ccc-DMEAPL, 50 μm i.d. × 50 cm (effective length 41.5 cm), separation voltage, 18 kV; column temperature, 25 °C; UV detection wavelength, 270 nm; water-plug injection: 30 mbar × 10 s; sample electrokinetic injection, 10 kV × 20 s. The four TCA were extracted with the solution of 10 mmol/L Na2HPO4 + 15 mmol/L citric acid + 4 g/L EDTA-2Na (pH 3.2). The FASS-OT-CEC method was validated in terms of linearity, sensitivity, selectivity, precision and accuracy. The LODs ranged from 3 to 7 ng/mL, the recoveries for the four TCA were all more than 80%. The developed method was successfully applied for the determination of TCs in the actual pig plasma samples.