The measurement of Hoffmann analytes, since it has been requested in Canada and then in some of the US states and in Brazil, has become necessary.

If a number of studies have already been published on the influence of some cigarette design tools on the Hoffmann analytes, no systematic study has been made on the role of cigarette paper main parameters, (porosity and citrate), and on filter ventilation.

To conduct this systematic study, we have used a face centred central composite design. This type of matrix allows a global analysis on the parameters studied, taking into account possible relationship of the second order.

For the 3 levels of variations requested in these type of study we have used :

• cigarette paper porosity : 20 ; 50 ; 80.
• amount of Na/K citrate : 0.6 ; 1.3 ; 2.0.
• levels of filter ventilation : 0 ; 20 ; 40.

It led to the manufacture of 17 different cigarettes, including repeatability experiments with 3 replicates at the central point of the design.

As the influence of the level of citrate in cigarette paper on CO and CO/Tar could be more complicated than a second order relationship, we have added at the centre point (50 Coresta, 20% ventilation), 2 levels of citrate : 0 and 2.5%.

The blend used in this study is a standard American blend. Cigarette were smoked for all Hoffmann analytes, including tar, nicotine and carbon monoxyde.

The methods used for the smoke analyses are :

• Nitric oxyde : chemoluminescence,
• Phenolic compounds : HPLC/Fluorescence,
• Heterocycles, unsaturated compounds, aromatic amines and PAH : GC/MS.
• Carbonyls : HPLC - DNPH derivatives
• TSNA : GC - TEA
• Ammonia : Ion Chromatography
• Hydrogen cyanide : ion selective electrode
• Heavy metals : AAS, ICP

The data analysis from the matrix study allows to :

• Optimise the cigarette design by using surface response, and model the Yi content of the different analytes as a function of porosity (X1), amount of citrate (X2) and filter ventilation(X3),
• Compare the effects of the different factors and their interactions,
• Establish correlations between the Hoffmann analytes and Tar, nicotine, CO , when changes in cigarette paper and filter ventilation are used .This will allow to save work in our laboratories.