IC Determination of Sorbate, Phosphate and Citrate in Reclaimed Tobacco

The reclaimed tobacco sample (0.150 0 g) was extracted by oscillation for 20 min with 50.0 mL of water to dissolve sorbate, phosphate and citrate from tobacco into water. The solution was filtered through 0.45 μm filtering membrane, and the acidity of the filtrate was adjusted to pH 11.0 with 0.25 mol·L^-1 NaOH solution. An aliquot of 5 mL of the filtrate was purified by passing through activated RP column. The first 3 mL of the eluate from the RP column were discarded and the latter 2 mL were collected for IC analysis. AS11-HC chromatographic column was chosen as stationary phase and 50 μL of the purified sample solution was introduced for IC separation. KOH solution was used as mobile phases passing through the column at various definite time intervals for gradient elution. Self-cyclic inhibition conductance detector was used for determination. Linearity ranges found were between 0.2-4.0 mg·L^-1 for sorbate, and between 2.0-40 mg·L^-1 for phosphate and citrate, with their detection limits (3s) of 0.022, 0.015, 0.010 mg·L^-1 respectively. 3 substantial samples were analyzed by the proposed method, giving values of RSDs (n=5) in the range of 0.18% to 0.74%. On the base of the 3 samples, standard solutions were added and analyzed by this method to test for recovery, giving results of recovery in the range of 97.3% to 103%.