This part of ISO 17226 specifies a method for determining the emission of formaldehyde from leathers. This method is based on high performance liquid chromatography (HPLC). It is selective and also allows the emission of other low molecular aldehydes and ketones to be observed. This part of ISO 17226 deals with the release of formaldehyde to the gas phase. Therefore, the obtained results are not comparable with the results of methods described in ISO 17726-1 and ISO 17226-2 which are based on extraction with liquid water.