| In order to improve food trait and its colour, taste, smell, reform antisepsis and process technic, some preservatives and sweeters are often added into foods, such as benzoic acid, sobic acid, sodium saccharin, sodium cyclamate. The components will interfere painstaking effort vein and procreation system, do harm to one's health. In national standard, the benzoic acid, sobic acid, sodium saccharin are determinated with the method of HPLC matched with an ultraviolet detector, but the Sodium cyclamate has no absorption in ultraviolet region, it was single derivated usually for being determinated with gas chromatography or high-performance liquid chromatography, and the process of the determinating was tedious and arduous. Also, the simultaneous determination of the Sodium cyclamate and the other sweeters and preservatives was limited, and the reports without being derivated of simultaneously determinating four components were not found. The price of the high-performance liquid chromatography is high and isnot suitable for rapid determinating the single Sodium cyclamate in middle and small labarotry. So it's important to build a HPLC method, in which four componects in food can be simultaneously analyzed, and a method which is suitable for simply, quickly and accurately determinating the Sodium cyclamate in common labaoratry.In this research, a high-performance liquid chromatographic method was described for the simultaneous determination of sodium cyclamate, saccharine sodium, benzoic acid, sorbic acid in food. The effect of operation conditions of HPLC such as the component of the mobile phase, the concentration of ammonium acetate, column and RID detector temperature, detector sensitivity were investigated. Isocratic elution was used for the baseline separation of the four additives in 7 minutes. The separation was performed on a reversed-phase Novo pak-C18 column, using a RID detector. Methanol:ammonium acetate in the mobile phase is 3:97. Column temperature was 30℃. RID detector sensitivity,64. Under the best condition, the calibration curves were linear between 0.7-200.0μg/mL. The correlation coefficient range from 0.9995-0.9999. The detection limits of the HPLC were 0.2-1.3μg/ml. The detection limits of the methods lies in that:sodium cyclamate:6.5μg/g; Sodium saccharin: 1.0μg/g; Benzoic acid:1.0μg/g; Sobic acid:1.0μg/g. The recoveries of four elements were 89.0%-104.5%. The relative standard deviation were 2.1 - 3.5%. Four elements were simultaneously determinated in 7minutes, and the method was used for determinating the really sample with good, accuate and satisfed results. An ultraviolet-visible spectrophotometric method has been decided according to the reaction of cyclamate with nitrite in acid medium followed by reaction of the excess of nitrite with iodide to form the triiodide anion, with absorption maximum wavelength at 350 nm. The best experimental condition has been confirmed:the concentration of HCl was 2.5 mol/L with its volume 1.0 mL, the concentration of NaNO2 was 2.0 mmol/L with its volume 1.6 mL, reaction time ten minutes in the gloomy place, the concentration of KI was 0.05mol/L with its volume 2.0 mL, reacting 10 min. Under the best condition, the detection limit for sodium cyclamate was 0.3μg/mL, the calibration curve was linear in the range of 1.0-14.0μg/mL, the detection limits of the methods lies in Sodium cyclamate:7.5μg/g. The linear eqution A= 0.5702c-0.0006, the linear relation coffecience r=0.9984 and the average recovery 102.3%-103.3%, the relative standard deviations were 0.71%-1.3%。The methods built for determinating sodium cyclamate in food has the feather of low cost, pupular and reliable utility in common laboratory for daily determination.
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