Sample concentration: Glucuronidase alone (0.1 % w/v), Glucuronidase/polymer mixture (0.1 : 2% w/v enzyme: polymer, pH 3.9, ionic strength 10 mM), Albumin/Acacia 1% w/v, PVP 1, 3 or 6% w/vSolvent: WaterCarrier, Filmogen: Albumin/acacia, dextran, HPMC, PVP