Minimising dead volume between cigarette and capture pad smoking machines has been shown to be critical in achieving total capture of total particulate matter (TPM) especially when smoking intensively. Less attention has been paid to dead volume in smoking experiments where the volatile component of mainstream smoke is captured in liquid impingers.

The objective of this study is to determine the impact of dead volume on the pressure drop of the capture system and how this changes the combustion conditions of the cigarette.

This was examined using two types of linear smoking machine (SM450 and SM450i with dead volumes of 19.73 and 11.26 ml respectively) and a puff capture device that could record the profile parameters as experienced by the test piece.

It was found that profile shape of puffs when impingers are added change from the “normal” smoking condition. Comparing no impinger with systems of increasing dead volume it was found that peak flow is reduced by 13% and 16% respectively, asymmetry increased for the largest dead volume from 1:1 symmetry to 5:4 asymmetry and that the peak maximum occurred at 1 s, 1.25 s and 1.35 s respectively.

The consequences for analytical measurement are discussed in the context of “peak clipping” and combustion temperature, notably that the elongation of peaks due to the elasticity of the drawn smoke present particular problems with some machine designs that utilise a single engine. Reducing the dead volume between smoking article and impinger system from traditional systems has a positive impact on the puff shape and peak velocity.