米糠油、椰子油和人造奶油中脂肪酸的HPLC-ELSD分析

由于紫外线吸收率低，脂肪酸通常在短紫外线波长下或通过RI检测器进行测量，这需要很长时间才能建立稳定的基线。柱前衍生法是脂肪酸的另一种众所周知的方法，但操作复杂。ELSD被认为是一种有效的脂质分析方法，提供了高灵敏度和稳定的基线，同时也消除了复杂的样品预处理。由于样品的碳链越短，挥发性越大，ELSD通常被认为是不充分的，难以测量脂肪酸。Application Note 2/4Application NoteAnalysis of fatty acids in rice bran oil， coconut oil and margarine UASGO Analysis of fatty acids in rice bran oil， coconut oil and margarin e by HPLC-ELS D Due to the poor UV absorbance ， fatty acids hav e been commonly measured at a shor t UV wavelength or by Rl detector， which takes a long time to establish a stable baseline. The method of pre -column derivatization is another well known approach for fatty acids， but the operation is compl i cated. ELSD is recognized as an effective method for the lipid analysis providing high sensitivity and a stab l e bas e l ine while also eliminat i ng t h e complex sample pre-preparation.As the sample becomes more volat i le with a shorter carbon chain， ELSD is normally considered inadequate and di ff icult to me a sure the fatty ac i d. This report describes the analysis using the E L S-2041， which is equipped with th e cooling capability in the evaporator， of the saturated and unsat u rated fatty acids of C10~ C18. Keyword ： HPLC， Saturated， Uns a turat e d， Fatty acid， C18 Column， ELSD， Capric ac i d， Lauric acid，Linolenic acid， Myristic acid， Linoleic acid， Palmi t ic acid， Oleic acid， Elaidic acid， Stearic acid， rice bran oil， coconut oil ， margarine PU-2089 Experimental Equipment： Conditions： P u m p ： PU-2089 Autosampler： AS-2057 Column oven： CO-2060 Detector： E L S-2041 Column： Develosil ODS HG-5 (4.6 mmlDx150 mmL， 5 pm) Eluent： A： 0.1% Acetic acid in Acetonitrile， B： 0.1% Acetic acid， C： 0.1% Acetic acid in Acetone Gradient condition： (A/B/C)， 0 min (85/15/0)， 20 min(85/15/0)， 20.05 min (5/0/95)， 30 min (5/0/95)，30.05 min (85/15/0) 1cycle： 45 min Flow rate： 1.0mL/min Column temp.： 40°C ELSD condition： Nebulizer temp.： 30℃ Evaporator temp.： 18℃ Gas flow rate； 1.4 SLM Injection volume： 10 pL 8 Fatty acids + Elaidic acid Standard sample ： 8 Fat t y acid s + Elaid i c acid R esults and Discussion Figu r e 1 s h ows t he chr o m a t o g r a m of a s t an d a r d mix t u r e o f 9 fa t t y a c i d s i n cl u d i n g a tr a n s f a t t y ac i d . A g oo d se p ar a t i on with i n 20 minu te s wa s a c h i e v e d fo r b o th s a t u r a ted a n d u ns at ur a t e d fa tt y a cids o f C 10~C 18， i n cl u d i n g th e E l a i d ic ac id o f t ran s f a tt y aci d . F i g u re 1. C hromatog r am of the standard mix t ure o f 9 fatty ac i ds i n c lu d ing a t r a n s fatty acid . 1： C apric acid [C 10] 0.5 mg/mL， 2： L auric a c id [C12] 0.2 mg/mL ， 3： L i n o len ic acid [C18：3] 0.1 m g /mL ， 4： My ri stic a c id [C14] 0.1 m g/m L ， 5： Li n o l e ic acid [C18：2] 0.2 mg/mL， 6： Palmitic acid [C 16]0.1 m g/mL， 7： O l eic acid [C18：1]0.2 mg/mL， 8： E l aid i c acid 0.2 mg/mL，9： St earic acid [C 18]0.1 mg/mL Th e c h r oma t o g r ams o f r i ce b ran o i l an d c oco n u t o i l are s h o w n i n f i gure 2 a n d 3， re s p e c t i ve l y . Fig u re 2. C hromatog r am o f rice bra n o il . Th e peak na m es are t h e same as in f i g u re 1. S a mple p r eparation： 1.0 g r ice bra n oi l was dissolved i n 10 mL of acet o ne. The sol u t i o n was t h en f i ltered t hrou g h a 0.45 um f i l ter. Figure 3. Chr o matogram of coco n u t oil Th e pea k names ar e the s ame as i n figu re 1. Sam pl e pr e pa ratio n ： 1.0 g c o co n u t oil was disso l ved in 10 mL of aceton e . The solut i o n was t h e n f i l t ered th r ough a 0.45u m f i l ter. A tr a ns f a tt y ac i d ， k n o w n a s t h e uns a t u r a te d f a tt y a c i d with t h e d ou b l e bo n d o f tr a n s t y p e ， i s n o t co n t a i n e d i n n a t ur a l veg e t a b l e o i l . I t is g en e r at e d du r i n g t he m a n ufa c tu rin g pr o ce ss of h y d r o g en a t e d o i l ，su c h as m arg ar i n e or sh o r t ening ， w h en h y d ro g en i s a d de d . S inc e the p o ssi bil i t y o f c au s i n g the h e a l t h i mp a ir m e n t， s u c h a s h e a r t d ise a se， h a s b e e n no ti c e d d ur i n g r e c en t ye ar s ， mo r e c ou n t r i e s a r e r egula t i n g t h e usa g e o f p r od u c t s which co n t ai n tr a n s f a tty ac id s. T h e c h r omat o g r a ms o f marg a r i n e it self a n d m ar ga r i n e ad de d w i t h E l a i di c a c id a r e sh o w n i n f i gur e 4 a n d 5， r es p ec t ive l y. F i g u re 4. Chr o matogram of Margari n e. T h e pea k n a m es are t h e same as i n fig u re 1. Sample p re p ara t ion： 0.5 g margarin e was d i ssolve d in 10 m L of acetone. F ig ur e 5. C h r o matogra m o f Mar ga r i n e add e d wit h Elaidic a ci d . The peak names are t he same as i n figure 1. Sample preparat i on： Ela i di c acid was added t o sa mp le of f ig ure 4 to adjust t h e co n centra t ion of Elaid i c ac i d to be 0.2 mg /m L.