The distribution of frother reporting to the concentrate along a bank of cells and the adsorption of collector to valuable particles are important as they determine the froth structure and flotation performance. An understanding of this is required in order to formulate better reagent addition strategies. Techniques to measure the frother concentration in samples taken from industrial flotation circuits, including dynamic surface tension measurements, have proven inconclusive due to the low concentrations used and the effects of hydrophobic particles. In this study, a method of measuring the concentration of non-adsorbed reagents on a laboratory scale has been developed. Batch flotation experiments were carried out on an industrial sulphide ore. The adsorption of the collector (SIBX) and frother (Dowfroth 200) to the solid particles was determined by measuring the concentration remaining in filtered liquid samples taken from the concentrate and tails. Analysis was carried out using UV spectrometry and TOC analysis. It was found that 20% of the frother is lost in the presence of the SIBX and that after 2 min, 63% of the SIBX had adsorbed to particles. The results also showed that an increase in the initial concentration of SIBX, and an increase in the conditioning time yielded a higher concentrate grade. (C) 2004 Elsevier Ltd. All rights reserved.