The quantitative effect of microextractor cell geometries on supercritical fluid extraction (SFE) efficiencies of polycyclic aromatic hydrocarbons (PAHs) and methoxychlor from octadecyl-bonded sorbents has been evaluated and compared to similar effects seen upon increasing the supercritical fluid density. For the PAHs studied, correlations between the fused ring number and the relative increase in recoveries have been established. SFE recoveries can be increased by greater than a factor of two by decreasing the diameter to length ratio from 1:20 to 1:1. The relative recovery increase upon decreasing the diameter to length ratio of the extraction vessel is dependent on the analyte extractability, increasing in proportion to the fused ring number for the PAHs. Recoveries increased linearly as a function of supercritical fluid density for the PAHs studied. The change in the relative recovery upon increasing the supercritical carbon dioxide density again was dependent on the analyte type, decreasing linearly with fused ring number. Although fluid density generally had the greatest effect on achievable SFE recoveries, the cell geometry had effects of a similar order of magnitude, highly dependent on the initial extractability of the analyte.
