Whether a simple and rapid dialysis method developed for analyzing food sweeteners, which does not require filling the dialysis membrane tube with samples, can be applied to ten preservatives including benzoic acid, sorbic acid, dehydroacetic acid, salicylic acid, and six paraoxybenzoic acid esters was examined. In addition, it was examined whether this method can be applied to foods that swell significantly with the addition of water, a process not possible with the conventional dialysis method. A suspension prepared by mixing 5 g of shredded food with the dialysis solution was placed in a dialysis container. Into this, a dialysis membrane tube filled with 2 mL of dialysis solution was placed; the dialysate (60% methanol and 0.5% sodium chloride) was added to bring the final volume to 50 mL. Dialysis was performed at room temperature for 90 min with constant mixing. Subsequently, the solution in the dialysis membrane tubes was collected and analyzed using a liquid chromatography photodiode array mass spectrometer. Recovery rates of 75.7%–109.9% and relative standard deviations ≤5.7% were obtained in the addition-recovery test. The developed method applies to preservatives and sweeteners and can easily process foods that swell significantly, thus expanding its range of application over conventional dialysis methods.