Simultaneous Determination Of Preservatives And Sweeteners In Food By HPLC Combined With Solid-phase Extraction

Background:In recent years,with the rapid development of social economy and the improvement of people's living and cultural level,there are higher requirements for the taste,quality and appearance of food.Therefore,more and more food additives are used on the market.In order to pursue economic benefits,some bad enterprises will use and abuse food additives beyond the standard.The existing research shows that the long-term over standard food additives will cause different degrees of damage to the health of the human body,and preservatives and sweeteners are the most important items in the detection of food additives,which have the characteristics of large amount of food use and wide range of use detection.At present,the national standard detection methods for a variety of preservatives and sweeteners are usually single detection or simultaneous detection of one or two,the detection time is relatively long,and the detection efficiency is relatively low.In recent years,it can be seen that some scholars have used the ultra-high performance liquid chromatography-mass spectrometry to detect a variety of preservatives and sweeteners in food at the same time.However,because the ultra-high performance liquid chromatography-mass spectrometry is relatively expensive,and some small and medium-sized laboratories do not have the corresponding conditions to equip,so this detection method has not been available in the market at present Therefore,it is necessary to establish a rapid,efficient and simple method for the analysis and detection of food chemical additives.As we all know,in a complete sample detection and analysis process,sample pre-processing technology is very important.Sample pre-processing accounts for 60%of the whole analysis process time,and 30%of the data error also comes from sample pre-processing.In recent years,nano materials have the characteristics of large surface area,good chemical stability and easy to reuse,which has attracted the attention of researchers.They are used as SPE adsorbents for practical sample analysis.Objective:A high performance liquid chromatography?HPLC?method for the simultaneous determination of six preservatives and sweeteners in food was established.At the same time,the role of Fe₃O₄nanometer material as solid extraction agent in improving the detection efficiency of food additives was discussed.Methods:Weigh and take appropriate amount of standards respectively and dissolve them with methanol to prepare benzoic acid,sorbic acid,methyl p-hydroxybenzoate,dehydroacetic acid,acesulfame and saccharin sodium standard stock solution with concentration of 1.0mg·mL^-1?dehydroacetic acid is dissolved with 20 g·L^-11 sodium hydroxide solution?.Dilute the prepared standard stock solution with ultra pure water step by step to a mixed standard solution with a concentration of100,50,20,10,5?g·mL^-1;filter the filtrate through a 0.45?m filter membrane for on-board measurement.ZORBAX SB-C₁₈?4.6 mm×250mm,5?m?was used as the column,and 0.1 mol·L^-11 ammonium dihydrophosphate methanol was used as the mobile phase for gradient elution;the column temperature was 30?,the flow rate was 1 mL·min^-1,and the detection wavelength was 230 nm.Fe₃O₄ nanoparticles were prepared by hydrothermal method.15 mg of Fe₃O₄ nanoparticles were weighed and put into a 15 mL centrifuge tube.1mL of mixed standard solution with a concentration of 5.0?g·mL^-11 was added.The mixture was mixed with a constant temperature mixer for 2 min and extracted by ultrasound for 6 min,and after the extraction is complete,a magnet was put at the bottom of the centrifuge tube.Under the action of the magnet,Fe₃O₄ nanoparticles will slowly gather at the bottom,and then the supernatant layer will be removed.Then,2 mL of methanol solution containing 20%acetic acid was used to elute Fe₃O₄ nanoparticles?1 mL twice,each time?.The eluate was collected and dried with nitrogen?55??,then dissolved with 0.5 mL of methanol,filtered with 0.22?m organic filter membrane,and finally 10?L was analyzed and detected by Agilent 1260HPLC.The chromatographic column is Symmetry Shield RP₁₈?4.6 mm×250 mm,5?m?,the mobile phase is 0.02 mol·L^-11 ammonium acetate?a?-methanol?b??V/V?=90:10,the flow rate is 1.0 mL·min^-1,the column temperature is 25?,the injection volume is 10?L,and the detection wavelength is 230 nm.Results:Using the HPLC method established in this experiment,six synthetic preservatives and sweeteners can be separated in 25 minutes,in the range of 5.0?g·mL^-1-100.0?g·mL^-1.There is a good linear relationship between the mass concentration and the peak area,and the correlation coefficient is 0.99983-1.00000.The accuracy,repeatability and stability of the method are all good,RSD is less than 2.46%?n=6?,and the average recovery is 93.6%-104.6%,the detection limit of acesulfame,saccharin sodium,benzoic acid,sorbic acid,dehydroacetic acid and methyl p-hydroxybenzoate is 0.63?g·mL^-1?0.09?g·mL^-1?0.08?g·mL^-1?0.07?g·mL^-1?0.62?g·mL^-1?0.16?g·mL^-1?S/N=3?,the limit of quantification is 2.08?g·mL^-1?0.28?g·mL^-1?0.25?g·mL^-1?0.24?g·mL^-1?2.05?g·mL^-1?0.51?g·mL^-1?S/N=10?.Five kinds of carbonated drinks were randomly selected and analyzed according to the established method to obtain the results of food additive content detection consistent with the peak time of standard products.Fe₃O₄ nanoparticles were used as solid-phase extractant to enrich food additives in complex matrix samples?soy sauce?.After optimizing the pre-treatment conditions of solid-phase extraction,such as the quality of adsorbent,adsorption time,solution pH,eluent solvent and resolution time,benzoic acid,sorbic acid and saccharin sodium were analyzed by HPLC.The results show that the three additives can be separated in 10 minutes,and the peak shape is good.In the range of 0.5-100?g·mL^-1,the linear relationship is good,the correlation coefficient R²>0.9999,the average recovery rate is 89.9%-106.4%,and the RSD is 0.41-2.53%.The method has good repeatability,precision and can meet the needs of practical sample determination.Conclusion:In this paper,a HPLC method for simultaneous determination of six food additives in carbonated beverage was established by optimizing the chromatographic conditions.Low detection limit;At the same time,it is simple,sensitive and fast.Fe₃O₄ nanoparticles are used as solid-phase extraction adsorbent in the sample pretreatment of complex matrix.The magnetic separation method reduces the time-consuming steps such as filtration and centrifugation in the sample pretreatment,improves the work efficiency,and is a better new method for the analysis and detection of food additives.