Determination of testosterone esters and nortestosterone esters in animal blood serum by LC-MS/MS.

A sensitive and robust confirmatory method for determination of steroid esters in blood serum is essential for reliable monitoring of possible illegal use of steroid hormones as growth promoters in meat production. A previously used sample preparation methodology was improved. The procedure consists of protein precipitation and removal of phospholipids by dispersive SPE Supel™ QuE Z-Sep (Sigma-Aldrich) followed by clean-up on alumina column and LC-MS/MS measurement.

Determination of testosterone esters and estradiol esters in bovine and porcine blood serum.

Monitoring of steroid esters in blood serum is desirable in order to detect the possible illegal use of natural hormones as growth promoters. A method for the determination of testosterone propionate, testosterone benzoate, testosterone isocaproate, testosterone decanoate and estradiol benzoate in bovine and porcine blood serum was developed. The procedure consists of protein precipitation and removal of phospholipids using a HybridSPE®-Phospholipid column followed by clean-up on a hydrophilic modified styrene polymer Supel-Select HLB column and LC-MS/MS measurement.

Persistence of chloramphenicol residues in chicken muscle tissue after a therapeutic dose administration.

One-day-old chickens were individually orally treated with chloramphenicol at a dose of 100 mg per kg of body weight per day for three consecutive days. After the final treatment, the groups of six birds were sacrificed in seven-day intervals up to 42 days. The muscle tissue collected from the breasts and legs of each bird was individually examined for the presence of chloramphenicol residues using a GC/MS-NCI analytical method, which was validated according to Commission Decision 2002/657/EC.

Observation of residues in tissues of chickens exposed to low dietary concentrations of chloramphenicol.

To investigate potential residues in tissues arising from naturally occurring low levels of chloramphenicol in plant material, feeding studies were conducted with chickens. A common chicken feed was prepared containing 0, 10, 50 and 200 μg kg chloramphenicol and levels were confirmed by LC-MS/MS. Four separate groups of broiler chickens, eight animals in each group, were fed all their 35-day life with this contaminated feed.

Development and validation of an LC-MS/MS method for the determination of six gestagens in kidney fats.

A method for the determination of residues of six steroids with gestagenic action (altrenogest, medroxyprogesterone acetate, megestrol acetate, melengestrol acetate, acetoxyprogesterone and chlormadinone acetate) in animal fat tissue was developed. The procedure consists of methanol extraction, clean-up on an alumina column and LC-MS/MS measurement. The method has been validated according to Decision 2002/657/EC.

Determination of chloramphenicol in urine, feed water, milk and honey samples using molecular imprinted polymer clean-up.

A method for determination of low concentrations of chloramphenicol in urine, feed water, milk and honey was developed. A comparison was carried out between a routinely used analytical method based on solid phase extraction (SPE-C18) for cleaning the extract and the new procedure for the sample preparation using columns based on the molecular imprinted polymers (MIP) principle. The extracts obtained from the MIP clean-up procedure were clean enough for chromatografic analyses.