SUMMARY. In many laboratories, the titrimetric method of Van de Kamer is used for the analysis of faecal fat content of patients suspected of steatorrhoea. We investigated the applicability of a mid-infrared (MIR) spectroscopic method, using an attenuated total re¯ection (ATR) accessory, and a new near-infrared (NIR) spectroscopic method. For the NIR method, sealed plastic bags containing the stool samples were used as transmission cells. Standardization was obtained using a previously described MIR method, with a NaCl¯ow-cell, as reference method. Partial least-squares regression was used for the calibration of each method. Full cross-validation of the calibration set was used for the internal validation of each method. Fifteen per cent of the stool samples could not be estimated with the ATR method within reasonable accuracy limits compared with the reference. The standard error of prediction of the NIR method was 1´1 g/dL. We conclude that the new NIR method is a promising technique for routine use. However, further experiments need to be done with triplicate measurements of each sample and the use of an external validation set.

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Laser‐light scattering measurements can be used for investigations of solid dissolution in a liquid. In this paper the dissolution of gypsum in water is followed by scattering and conductance measurements. Both types of measurement are carried out simultaneously. The sensitivity of the scattering technique and its special applicability in solubility determinations is discussed.