Similar to the traditional or HC HPLC method, this improved
HPLC method provides good linearity (r2 ≥
0.999) for all the studied
phenols in the concentration ranges tested (Table S1). The calibration
curve and the linear regression equation for each compound
were shown in Fig. S4 in Supplementary data. For tobacco smoke
analysis, the reference (KY3R4F) cigarettes were used as controls
during method validation. Although the two tested PFP columns
can separate all the phenol compounds in pure standards (see
Fig. 2), the results shown that the Luna PFP (2) column has better
retention and resolution for these analytes in real tobacco samples
as demonstrated in Fig. S5 in Supplementary data, possibly due
to the smaller pore size and higher hydrophobic value (H) [19] of
Luna PFP (2) phase compared to that of Purpuit PFP phase. There
are interferences from sample matrix components eluted in the
front of the analyte peaks with the Pursuit PFP column, especially
for sidestream smoke samples (Fig. S5). Therefore, the Luna PFP (2)
column was used for further method validation and sample analyses.
The analyte peaks in tobacco samples were identified by their
retention times as compared to those in the calibration standards
and further confirmed by the spiked analyte peaks using laboratory
fortified matrix (LFM) samples as shown in Fig. 1. It should
be noted that although guaiacol is not analyzed by the HC methods
[11,12], this compound can be determined by both GC–MS and
HPLC methods as described in a recent publication [9]. In this study,