A novel sorbent for the determination of clenbuterol in bovine liver

The use of three C-18 sorbents in matrix solid phase dispersion (MSPD) for the determination of clenbuterol in bovine liver fortified at 5 ng g(-1) is described. MSPD grade C-18 sorbents give rise to more efficient blending and packing of the material for subsequent washing and analyte elution in comparison with a non-MSPD grade C-18 sorbent. Following enzymatic deconjugation of the liver extracts, radioimmunoassay is used as the method of determination. The mean recovery of clenbuterol with all sorbents is comparable and within the range 86-96% in two intra-assay studies (n = 3). The liver extracts in each case are highly coloured. The variation in recovery is observed to be lowest with MSPD grade C-18 (end-capped). This sorbent was used in further studies to evaluate the use of solid phase extraction (SPE), post MSPD, with normal phase aminopropyl or mixed mode cation exchange columns for extract purification. The mean recovery of clenbuterol (n = 4, inter-assay study) following MSPD and normal phase SPE clean-up was 95 +/- 15% and 89 +/- 9% at fortification levels of 1 and 2.5 ng g(-1), respectively.