Evaluation of a reagent-injection flow injection technique for sample background absorption elimination: determination of chloride in cigarettes

The applicability of reagent-injection flow injection (FI) technique in elimination of background absorption was evaluated by using the FI determination of water-soluble chloride in cigarettes, based on the mercury thiocyanate method, as a model. Some parameters of the proposed reagent-injection FI method were optimized and the proposed procedure had a linear range of 0–7.5 mg l−1 Cl, a detection limit of 0.02 mg l−1 Cl, a sampling rate of 60 h−1 and a relative standard deviation of 0.1% at 5 mg l−1 Cl. Eight cigarette samples were analyzed by this proposed reagent-injection FI method and the referential membrane dialysis FI procedure. The relative errors were <4.3%, and paired t-test shows that there are no significant differences between these two methods. As no dialysis unit was needed, the reagent-injection FI method has much simpler flow system than the existed CFA and FI methods.