VNU JO U R N A L OF SCIENCE Nat., Sci & Tech., T XX N01, 2004 RESEARCH ON IDENTIFYING PAHS IN VEGETABLE OIL PRODUCED FROM SOME PLANTS IN OPEN ENVIRONMENT Do Q u a n g H u y , Le N h u T h a n h H anoi U niversity o f Science, V ietnam N a tio n a l U niversity S u m m a r y Some of vegetable oils were used to identify the Polycyclic Aromatic Hydrocarbons (PAHs) Contamination of PAHs in vegetable oils was due to technological processes or environmental sources PAHs were detected in vegetable oils, including raw coconut oil from Philippine, soya bean and oliverapeseed oil from Vietnam Concentration of PAHs was found in coconut oil, the maximum concentration was 22.048 |ig/kg PAHs’ concentration in soya bean, olive-raspeseed oils was low, it was reduced during refining Benzo(a)pyrene wasn’t detected in all samples, the maximum concentration of other PAHs was 10.640 ng/kg PAHs concentration in raw vegetable oils were higher than refined oils I n t r o d u c t io n The p ollu ta n ts were tr a n s p o r t e d into land and w a te r th ro u g h the air, and acc u m ulate d in plants This was one of the re aso n t h a t cause s PAHs in some seeds and fruits - m aterial for oil production With the target of controlling food quality a nd explaining the a p p e a n c e of PAHs in cooking oil, we have carried out a res ea rch to set up a method to identify PAHs q u a n ti t y in some kinds of cooking oil, olive oil, soybean oil a nd coconut oil The r e s u l t shows t h a t t h e r e were PAHs in some of them The r ela tio n ship betw een p lan tin g e n v iro nm en t an.d producing process with the a p p e a n c e of PAHs in vegetable oil has been being explained E x p e r im e n t a l 2.1 M a te r ia ls , c h e m ic a ls a n d i n s t r u m e n t s The w coconut oil, soya bean and olive-rapeseed oil was investigated S t a n d a r d solution of PAHs in cyclohexane was used Solution s t a n d a r d of n a p h th a le n e , ace n ap h th y le ne , ace naph thene , phenanthrene, an th ce n e, flu oran then e, fluorene, pyrene, benz o(a)anthracene, chrysene, benzo(bjka)fluoranthenes, benzo(e)pyrene, benzo(a)pyrene, perylene, indeno(123cd)pyrene, dib en z (ah)a nth ce n e, benzo(ghi)perylene ta in in g 500 pg/àl P h e n a n t h r e n e - d l O , p e r y l e n e - d l a nd benzo(e)pyrene-dl2 wa s supplied by Supelco, c on ta in ing ng/àl each was p r e p a r e d in cyclohexane I n t e r n a l s t a n d a r d solution of n a p h t h a l e n e - d 8, a c e n a p h t h y le n e - d i o , p h e n a n t h r e n e - d i o , p e r y l e n e - d l and b e n zo(e )pyrene-dl2, 0,1 àg/ml each was p r e p a r e d in cyclohexane All these 63 Do Q u a n g H uy, Le N h u T h a n h 64 solutoins were stored a t 5°c The solvents for ex tra ct a nd clean up were cyclohexane, d im ethylform am ide, ethylac etate , n-hexane Silica gel, 70-230 mes h for column c h ro m a to g r a p h y was removed i m p u r itie s possibly p resen t by h ea tin g overnight at 50°c Before use, standardize by adding 10 % (v/v) of distilled water, after agitation allow to s t a n d for h Bio-Bead S-X3, 200-400 mesh was also used in cleaning proceduce The H e w l l e t - P a r k a r d 5973 m as s sp ectrom eter interfaced with Agilent 6890 GC was used HP-5, 30 m X 0,25mm fused silica column wa s use d with h e liu m as the carrier gas a t 1.2ml/min, p r e s su re 6.31psi Splitless injection 250°c was employed The oven t e m p e r a t u r e was p ro g ram m ed 70°c, min, 5°c/min, 280°c, and keeping a t 280°c unt il all com ponents were eluted The m ass sp e ctro m eter p a r a m e t e r s used were as follows: electron impa ct energy 70 eV, source t e m p e r a t u r e 250°c, t r a n s f e r line 280°c In the SIM mode, th e ions monitored were m/e 136, 68 ( n a p h t h a l e n e - d 8), m/e 128, 129 (nap h th a le n e), m/e 162, 164 (acenaphthyle ne-dlO), m/e 151, 152 (acenaphthylene), m/e 153, 154 (ac enaphthene), m/e 164, 166 (fluorene), m/e 186,188 (p h e n a n th r e n e - d lO ), m/e 176,178 (p h e n a n th r e n e , a n th ce n e), m/e 200, 202 (fluoranthene, pyrene), m/e 226,228 (benzo(a)anthracene, chrysene), m/e 250, 252 (benzo(bjka)fluoranthenes, benzo(e)pyrene, benzo(a)pyrene, perylene), m/e 260, 264 (peryl ene-dl 2, benzo(e)py re ne-dl2), m/e 276, 277 (indeno(123-cd)pyrene, benzo(ghi)perylene), m/e 278, 279 (dibenz(ah)anthracene), Figure 2.2 C le a n u p p r o c e d u r e 25 gram of vegetable oil in 250 ml s e p a r a t i n g funnel, add ml i n te r n a l s t a n d a r d solution was solved in 100ml cyclohaxane The m ix ture was extr a cted by dimethylform am ide : H 20 (9:2, v/v) t h ree tim es with portions of 50 ml, 25 ml, 25 ml The extract of sa m ple was diluted with 100 ml of % N a 2S solution After adding 50 ml cyclohexane, the m itu re was e xtracted again with 25 ml of dimethvlfor m am ide : w a t e r (9:2; v/v) The e x tr a c t was w a sh e d with distilled w a t e r and t h e n dried with a n h y d r o u s sodium sulfate The e x tr a c t was c o n ce n tra te d on a rotary evap o rator to ml a t 40°c C h r o m a to g r a p h y column (500 m m X 0.6 m m i.d.) was packed a gram of: silica gel (content 10 % of water) Load p r e p a r e d e x tr a c t on th e column 90 ml of cyclohexane wa s used as a solvent to clean up a nd elute PAHs from column Discard 10 ml of first fraction (FI), a n d concentrate 80 ml of secơnd fration to ml (F2) Bio-Bead S-X3 column ( 300 m m X 20 mm) was used to clean up a g a i n th e F2 solution The m ix tu re of cyclohexane : e th y lac eta te (1:2, v/v) was u sed as a solvent to clean up and elute PAHs from column Flow r a t e of th e m ix tu re of cyclohexane : eth ylacetate (1:2, v/v) wa s ml/min Adding ml of e th y lac eta te to F2 solution, load this solution on the column Collect th e 50 - 120ml fractiort a nd c o n cen tr ate on a Research on id e n tify in g p a h s in vegetable oil fro d u c e d f r o m 65 rotary e v a p o r a to r to ml T r a n f e r a residue into a sa m ple vial, dr ynes s u n d e r nitrogen st r e a m , a n d dissolve in 100 àl toluene This solution was used to identify PAHs on GC-MS R e s u lt s a n d d i s c u s s i o n A sa m p le of r a w coconut oil wa s produced in Philippine was analyzed to identify PAHs The sa m ple h a s not been refined, still h a s distinctive smell and colour of th e i n p u t m aterial CM O si CO CD i c ễc «o 2c II II 4.0e4- U - CL Q_ < Soo CN 0CD II Is c § N - (O CO 0 o Ọ CNCỘ 0)