Production and stability testing of incurred reference materials for the anabolic steroid trenbolone in bovine urine†

Abstract

The production of stable reference materials with incurred residues of veterinary drugs is necessary for the validation of methods of analysis, including the determination of critical performance characteristics. A reference material for trenbolone in bovine urine was produced and the long-term stability was tested. From a pilot 16 week stability study on seven batches containing different additives it was concluded that the use of preservatives does not improve the stability of the residue. A final batch of reference material of 800 vials each containing 5 ml of urine with a target concentration of 5 micrograms l-1 was prepared. The homogeneity and long-term stability of the material were tested. The material was found to be homogeneous. Based on the results of a 52 week stability study it was concluded that the material is stable, using the current analytical methodology. For the development of reference materials, highly accurate and precise analytical methods are necessary. However, the current analytical methodology is not suitable for full evaluation and certification. Currently, a new LC-MS method is being developed. After validation of this method, the stability and homogeneity study will be repeated.

Ultrasound-enhanced enzymatic hydrolysis of conjugated female steroids as pretreatment for their analysis by LC–MS/MS in urine

“…Methods reported by this organism have described reference hydrolysis steps developed at 37 C using acetate buffers that enable the process time to be shortened to two hours. 14 One alternative to enhance enzymatic hydrolysis is assistance with ultrasonic energy, 15 still an emerging field. The mechanism through which ultrasound enhances enzymatic reactions has not been elucidated.…”

Immunofiltration as sample cleanup for the immunochemical detection of β-agonists in urine

“…Twenty lyophilised reference blank bovine urine samples (code BOV01-BOV20) were obtained from the bank of reference samples prepared by the European Community Reference Laboratory (CRL) the National Institute of Public Health and Environmental Protection (RIVM, Bilthoven, The Netherlands). 13 These samples were taken from a broad range of animals including veal calves, fattening bulls, heifers, pregnant cows and mature bulls. Each sample was reconstituted in 5 ml of deionised water.…”