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 a nd packing of the material for subsequent washing and analyte elution in co mparison with a non-MSPD grade C-18 sorbent. Following enzymatic deconjugat ion of the liver extracts, radioimmunoassay is used as the method of determ ination. The mean recovery of clenbuterol with all sorbents is comparable a nd within the range 86-96% in two intra-assay studies (n = 3). The liver ex tracts in each case are highly coloured. The variation in recovery is obser ved to be lowest with MSPD grade C-18 (end-capped). This sorbent was used i n 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-as say 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.