Rapid Detection Technology Research Of Preservatives In Export Vegetables

Vegetable is one of the essential food in people’s daily diet. It can provide many kinds of vitamins and minerals. But vegetables are susceptible to the infection of fungi, bacteria and other microorganisms during field production, resulting in mildew corruption after picking, so the preservatives after vegetables picking plays an important role.Preservatives are often made into various preparations spraying on the surface of vegetables, or directly soaking vegetables in, or adding into the vegetable packing materials, but these measures are easy to cause vegetables and processed vegetables retaining preservatives.Vegetable preservatives are mainly divided into natural preservatives and chemical preservatives. Natural preservatives contain tea polyphenols,chitin and its derivatives, lysozyme, antibacterial agents of spices, etc..Compared with natural preservatives, chemical preservatives have the advantages of simple equipment, low investment and low cost, so they are widely used in vegetable production and storage. However, most of the chemicals are toxic and residual, which have adverse effects on human health. The amount and the residual amount of chemical preservatives need to be kept in a certain range to ensure food safety. People do not only evaluate preservative effect by agricultural products and improving the effectiveness of the economic benefits, but also focusing on the no damage to the environment and healthily social benefits. Therefore, the detection ofpreservative residues in vegetables has a very important significance. In the national standards, the kinds of the vegetable preservatives residues which are quantified are not many, and the quantitative limit is relatively high. Thus, the detection of more kinds of vegetables, low limit of quantification, simultaneous detection of a variety of preservative residues become development needs, which can not only ensure the vegetable healthy, but also be a large number of loss of reduction in manpower and material resources.Chongqing production of vegetables not only meet the local needs, but also export to China Hongkong and Taiwan, Korea, Japan and other places.Inland vegetable export in long distance transportation of perishable moldy,non-standard use or abuse of vegetable preservatives may lead to the excessive preservative harming people’s health. A large number of testing projects and a long test cycle not only cause inconvenience to the acquisition of fresh vegetables and raw materials, exporting customs clearance, but also led to a decline in the quality of vegetables and economic losses and so on. How to shorten the period of vegetable inspection and put forward a new requirement for rapid detection.Part Ⅰ Simultaneous determination of 16 preservatives in exportvegetables by GC-MSObjective: Establish a method for the rapid detection of 16 kinds of preservative residues in vegetables by Quick, Easy, Cheap, Effective,Rugged, Safe(Qu EChERS) and gas chromatography mass spectrometry(GC-MS). Methods: Leafy, eggplant fruit, beans, melons, and tubers vegetables were used as raw materials. The samples were extracted with acetonitrile. The extracts was purified by QuEChERS, and then detected by GC-MS with external standard method. Quartz capillary column: DB-5MS column(30 mm×0.25 mm, 0.25 μm); carrier gas: high purity helium;flow rate: 1.2 mL/min; sample volume: 1 μL without diverting sampling;inlet temperature: 250 ℃; ion source: EI source, the ionization energy of70 eV; ion source temperature: 230 ℃; pole temperature: 150 ℃; interface temperature: 280 ℃; solvent delay: 5 min. Results: There were good linear relationships in the range of 0.02~2 mg/L(0.9990~0.9997). The limits of detection of 16 preservatives were 0.004~0.965 μg/kg. The limits of quantitation of 16 preservatives were 0.013~3.217 μg/kg. At spiking levels of 0.05, 0.1 and 0.25 mg/L in different matrices, average recoveries were between 70.0%~120.0% with the RSD between 0%~16.9%.Conclusion: This method is rapid, simple, sensitive, and can meet the detection requirements of 16 kinds of preservative residues in vegetables.Part Ⅱ Simultaneous determination of 18 preservatives in exportvegetables by UPLC-MS/MSObjective: Establish a UPLC-MS/MS method for the determination of 18 preservatives in vegetables. Methods: Leafy, eggplant fruit, beans,melons, and tubers vegetables were used as raw materials. The samples were extracted with hexane-ethyl acetate(1:2,V/V). The extracts was purified by dispersive-SPE, and then detected by UPLC-MS/MS with external standard method. The analytes were separated on a ACQUITY UPLC BEH C18(50 mm×2.1 mm, 1.7 μm), positive and negative ion electrospray mode was eluted by gradient with acetonitrile and 2 mmol/L ammonium acetic. And the flow rate was 0.3 mL/min, the column temperature was 40 ℃ and the injection volume was 1 μL. Conditions of MS/MS in positive mode: electrospray voltage 5500 V; atomization gas pressure 50 Pa; air curtain gas pressure 30 Pa; assist gas pressure 50 Pa;ion source temperature 550 ℃; collision room entrance voltage 10 V.Conditions of MS/MS in negative mode: electrospray voltage-4500 V;atomization gas pressure 50 Pa; air curtain gas pressure 30 Pa; assist gas pressure 50 Pa; ion source temperature 550 ℃; collision room entrance voltage-10 V. Results: Good linear relationship(0.9904~1.0000) was observed within the concentration range of 5.0~100.0 μg/L. The limits of detection of 18 preservatives were 0.04~4.16 μg/kg. The limits of quantitation of 18 preservatives were 0.13~13.85 μg/kg. At spiking levels of 10, 20 and 50 μg/L in different matrices, average recoveries were between 76.0%~120.0% with the RSD between 0.3%~14.8%. Conclusion:The method is reliable, sensitive with wide linearity range, and strong practicability, which can be used for qualitative and quantitative analysis of 18 preservatives in vegetables.