Abstract:
β-agonists (clenbuterol, salbutamol and terbutaline) are adrenergic drugs, which
were originally developed for the treatment of chronic obstructive pulmonary diseases,
especially asthma. Additionally, these drugs benefit the meat-producing industry by
enhancing muscle accretion and diminishing muscle protein breakdown. Therefore, β-
agonist drugs have been used as growth promoters in livestock. However, the misuse of
β-agonist drugs as growth promoters have been banned because they cause sickness and
heart complications to humans. Analysis of β-agonist residues in meat is, therefore,
essential for consumer protection.
This work emphasizes the method of development of non-aqueous capillary
electrophoresis-mass spectrometry NACE-MS for the analysis of three β-agonist residues
(e.g., salbutamol, clenbuterol and terbutaline) in porcine muscle. The method was
validated and compared with high performance liquid chromatography (HPLC)-MS-MS.
NACE-DAD was first optimized using two factorial design. The optimum NACE-DAD
condition was obtained from 18 mM ammonium acetate in methanol: acetonitrile: glac.
acetic acid (66:33:1 by volume) using the injection at 50 mbar for 4 s, voltage of 28 kV
and temperature of 24 ºC. The NACE-DAD method sensitivity was enhanced using a
high sensitivity detection cell (bubble cell) or a MS detector. The MS interface was
achieved using an electrospray interface using sheath liquid consisting of of 5 mM
ammonium acetate in methanol (80 % v/v), delivered at a flow rate of 2 μL/min.
The injection conditions were 50 mbar and 10 kV for 12 s, spray tip potential was 2300,
Nozzle Potential was 130 and seconds per spectrum scanning (spectrum acquisition
setting) was 3.00. The method was validated with high performance liquid (HPLC)-MSMS
and data showed that NACE-MS provided wider linearity range, and comparable
precision and recoveries. The NACE-MS provided the lower limit of detection, LOD (0.3
vs 1.6 ppb), shorter analysis time (18 vs. 25 min) and lower cost than HPLC-MS-MS (9
fold cheaper). However, the NACE-MS method should be improved to enhance the
reliability of the assay since the ion suppression from porcine muscle could act upon the
results.
The NACE-MS was applied for the determination of porcine muscle in
comparison with HPLC-MS-MS method and the values reported by the Ministry of Public
Health, Thailand. The data obtained no statistical differences between the two methods
and the values reported from the Ministry of Public Health, Thailand (P > 0.05),
at 95% confidence level, calculated from salbutamol.