As a strong carcinogen, Benzopyrene is able to cause cancers in skin, lung and digestive tract. Among 200 discovered polycyclic aromatic hydrocarbons and their derivatives, benzopyrene has the highest carcinogenicity and pollution degree. Oil crops in the drying, baking and refining processes and animal and vegetable oil after heated by high temperature are extremely vulnerable to benzopyrene contamination. The contaminated animal and vegetable oil seriously poses a serious threat to human health. In this paper, a simple and fast sample pretreatment method is created through the Cleanert® BAP solid-phase extraction column to guarantee accuracy and reproducibility of the detection of benzopyrene in the oil.
Weigh about 0.300 g grease sample, dissolved in 5 mL n-hexane and fully mixing on the vortex mixer.
Conditioning 30 mL n-hexane. (Attention: continuous adding n-hexane into the column and keep n-hexane above the upper sieve plate of column to avoid air entering the column.)
Loading sample: add the dissolved grease sample onto the Cleanert® BAP cartridge, attention that the upper sieve plate cannot dry.
Elution: add 80 mL n-hexane and receive with 150 mL spin steaming bottle until 80 mL of n-hexane is completely dropped natural. In order to ensure the recovery rate, the elution volume of n-hexane can be increased, and the maximum volume up to 120 mL.
Rotary evaporation: rotate evaporation the eluent in 45 °C water bath to dry, if there are still oil droplets can't dry out, it indicate that the grease content in the sample is higher, and purification is incomplete, it need to add 80 mL n-hexane into of oil droplets to made new sample, and using a new column to repeat the purification process;
Concentration: leaching spin steaming bottle three times with a total amount of 10 mL n-hexane, merge eluent to nitrogen blowpipe and blow dry with nitrogen. Add 300 μL n-hexane to nitrogen blowpipe, thoroughly mixing above the vortex mixer.
Avoid n-hexane evaporation during vortex process. Transfer 300 μL n-hexane above into insert-pipe of 1.5 mL sample bottles and load sample for analysis.
HPLC column: Venusil® ASB C18 250 mm × 4.6 mm, 5.0 μm (P/N: VS952505-0)
Flow rate: 1.0 mL/min
Mobile phase: acetonitrile:water = 88:12
Emission wavelength: 406 nm; excitation wavelength: 384 nm
Results and Discussion
This method using Cleanert® BAP SPE cartridge for the purification treatment of benzo (a) pyrene in a vegetable oil and the recovery rate of 5 μg/kg addition level is 99.49%. The chromatogram results of using Venusil® ASB C18 are shown in Figure 1-3.
Table1 Recovery rate of benzo (a) pyrene