Determination of ractopamine in animal hair: Application to residue depletion in sheep and residue monitoring

Rapid Screening of β-agonists in Animal Hair by Thermal Desorption Electrospray Ionization Mass Spectrometry

BACKGROUND

Even though the usage of β-agonists in livestock has been banned in many countries, β-agonists abuse is still out of control towing to the time-consuming and complicated determination technique.

OBJECTIVE

This study applied ambient thermal desorption electrospray ionization mass spectrometry (TD-ESI/MS) as a new strategy for rapidly screening 7 β-agonists. As it does not require pretreatment, this method allows in-site and real time detection.

METHODS

Samples were collected directly using a simple metal probe. Analytes on the probe were desorbed and ionized in TD-ESI, after which analyte ions were detected using a triple quadrupole mass analyser.

RESULTS

The results showed that thermal desorption temperature of 320 °C and nebulizer pressure of 3 psi demonstrated the highest sensitivity. Excellent linear relationships were obtained in concentrations ranging from 10 to 400 μg/kg. The limit of detection of the method was 1-10 μg/kg with relative standard deviation of 7.2%-14.6%. A positive sample was verified using high performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry, consistent with the results from TD-ESI/MS.

CONCLUSIONS AND HIGHLIGHTS

This method was the first to apply TD-ESI/MS to rapid analyse β-agonists in livestock hair which was proven to be accurate, fast and environmentally friendly. Because qualitative screening for each analysis was completed within approximately 1 min, it seems to contribute to prevent non-compliance animal-derived food flowing into the market.

Evaluation of β-agonists in blood meal: Validation of determination method and potential pathway for reentry into the environment

β-agonists, which have been illegally used in animal production in some countries, can induce bioaccumulation when blood is converted by rendering into blood meal. Unfortunately, available data on this topic are scarce, which result in lack of risk assessment. Therefore, in this research, a method for simultaneous determination of 22 β-agonists in blood meal by liquid chromatography coupled with tandem mass spectrometry using isotope dilution was developed. The recoveries of the developed method ranged from 68.6% to 118.8% with RSD at below 20%. the limit of detection (LOD) is blew 1 μg/kg. The change in agonist form added and incurred blood into blood meal and long stability of β-agonist in blood meal were studied. Then, we analyzed blood meal for 22 agonists using this method. The results suggest blood meal is a possible pathway for agonist reentry into animals. Potential risks of agonist residues in blood meal were examined. This study is the first to explore source of β-agonist residues in blood meal, change in processing produce and stability in stored stage.

Elimination and Concentration Correlations between Edible Tissues and Biological Fluids and Hair of Ractopamine in Pigs and Goats Fed with Ractopamine-Medicated Feed

Ractopamine (RAC), a β-adrenergic leanness-enhancing agent, endangers the food safety of animal products because of overdosing and illegal use in food animals. Excretion and residue depletion of RAC in pigs and goats were investigated to determine a representative biological fluid or surface tissue for preslaughter monitoring. After a single oral gavage of RAC, 64-67% of the dose was excreted from the urine of pigs and goats within 12-24 h. RAC persisted the longest in the hair of pigs and goats but depleted rapidly in the plasma, muscle, and fat. Urine and hair were excellent for predicting RAC residues in edible tissues of pigs, whereas plasma and urine were satisfactory body fluids for the prediction of RAC concentrations in edible tissues of goats. These data provided a simple and economical preslaughter living monitoring method for the illegal use and violative residue of RAC in food animals.