Investigation of applicability of a mid-infrared spectroscopic method using an attenuated total reflection accessory and a new near-infrared transmission method for determination of faecal fat

In many laboratories, the titrimetric method of Van de Kamer is used for th e 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 reflection (ATR) accessory, and a new near-infr ared (NIR) spectroscopic method. For the NIR method, sealed plastic bags co ntaining the stool samples were used as transmission cells. Standardization was obtained using a previously described MIR method, with a NaCl flow-cel l, as reference method. Partial least-squares regression was used for the c alibration of each method. Full cross-validation of the calibration set was used for the internal validation of each method. Fifteen per cent of the s tool samples could not be estimated with the ATR method within reasonable a ccuracy limits compared with the reference. The standard error of predictio n 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 b e done with triplicate measurements of each sample and the use of an extern al validation set.