| ObjectiveFumonisins are a group of structurally related mycotoxins produced by a number of Fusarium species. The most prevalent of these mycotoxin in contaminated corn is FB1, which is believed to be the most toxic. FB1 has been detected in maize and maize-based products all over the world. FB1 is known to be the cause of equine leukoencephalomalacia and porcine pulmonary edema syndrome.Available epidemiological evidence has suggested a link between dietary fumonisin exposure and human oesophageal cancer in some locations with high disease rates.There are not investigations about Fumonisin B1 Contamination in foodstuff of our native Country, domestic and overseas professors mostly study on the FB1 contamination of home-grown corn in high-risk, low-risk areas for esophageal, and parts of our native country. This investigation was done to find out Fumonisin B1 Contamination of Maize in six provinces in our native Country and offer basic datas for establishing FB1 standard in corns,protecting human's health and promoting international trade.MethodGrind corn laboratory sample to yield material of such size that can 90％is retained between 250μm-500μm mesh screens.Weigh 50g test portion into 250 ml plastic centrifuge bottle.Add 100 ml methanol-H2O solution, C(g), and homogenize 3 min at 60％full speed setting. Alternatively, blender may also be used at the same speed settings, but period o5 min should be allowed for complete extraction. Centrifuge mixture 10 rain at 500×g and filter supernate through fluted filter paper. Filtrate should have apparent pH ca 5.8. If necessary, adjust pH to 5.8-6.5 with 1M NaOH. Fit SPE cartridge to SPE manifold. Condition cartridge by washing successively with 5 ml methanol, C(a), followed by 5 ml methanol-H2Osolution, C(g).Apply 10ml filtered extract to cartridge, while maintaining flow rate≤2 ml/min.Wash cartridge with 5 ml methanol-H2O solution followed by 3ml methanol.Do not let cartridge dry. Elute fumonisins with 10 ml acetic acid-methanol solution, C(e), at flow rate≤1 ml/min. Collect eluate in 20 ml glass collection vial. Sequentially transfer aliquot of eluate to 4 mL glass vial, while evaporating solvent to dryness under stream of N2 at ca 60℃. Rinse collection vial with 1 ml methanol and add rinsing solvent to 4 ml vial, washing sides of vial to concentrate residue at its base. Evaporate additional methanol to dryness to ensure that all acetic acid has evaporated. Dried residues may be retained up to 1 week at 4℃prior to LC analysis.Transfer 25μl fumonisin standard working solution, C(m), to base of small test tube. Add 225μl OPA reagent, C(k), mix, and inject 10μl into LC system within 1 min after addition of OPA reagent. Adjust sensitivity settings of fluorescence detector so fumonisin B1 standard-OPA derivative yields at least 80％recorder response.Redissolve residue from Din 200μl methanol. Transfer 25μl solution to base of small test tube and add 225μl OPA reagent.Mix and inject 10μl solution into LC system within 1 min of adding OPA reagent.All fumonisin peaks should be on scale. Peak identity should be confirmed by comparison of retention times in extracts with those observed for individual fumonisin standard. If fumonisin chromatographic peaks exceed those of fumonisin standard solution,make additional dilutions of extracts with methanol and repeat derivatization with OPA reagent.ResultsThe limited concentration of detection of the HPLC was 2ng/ml.Its Specificity, stability, repeatability and reproducibility could fufill requirements. In corn samples from Henan,FB1 was detectable in 97.71％of the samples, five provinces are all 100％. The level of FB1 in corn samples from Sichuan(19565.21ng/g) is the highest, The rest of five provinces are Guangxi(11261.40ng/g),Guangdong(4808.37ng/g),Hubei(2293.66ng/g),Henan(975.80ng/g),Jilin(901.85ng/g) in turns.But according to th e median concentrations, The level of FB1 in corn samples from Sichuan(8176.94ng/g) is the highest, The rest of five provinces are Guangxi (5504.84ng/g),Guangdong (3733.76ng/g),Hubei(1006.01ng/g),Jilin(795.75ng/g),Henan(315.56ng/g)in turns. Fumonisins B1 levels in Maize in six provinces in our native Country in the range from 2ng/g to 71121.39ng/g (Median:2105.93ng/g, mean: 6633.11ng/g).According to the analysises by the Wilcoxon signed rank test,the level of FB1 in corn samples from Sichuan was significantly higher than from Hubei (P＜0.05),Jilin and Henan (P＜0.01). Guangxi and Guandong was also significantly higher than Jilin and Henan (P＜0.01).ConclusionThe range of fumonisins B1 levels in Maize is from 2ng/g to 71121.39ng/g (Median: 2105.93ng/g, mean:6633.11ng/g) in six provinces in our native Country.And our research finds the FB1 contamination in maize of our native country is more and more severe from North to South.
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