ADV06-15_1-412

trans

Fat: Resolving

cis

and

trons

FAME Isomers

ByJulie Kowalski, Innovations Chemist

• Highly polar Rt-2560 column resolves ind ividual

cis

and

trans

FAME isomers.

• Analytical reference mixes for quantifying FAMEs in foods and dietary supplements.

• Use column and reference mixes to meet new

trans

fat labeling regulations.

Concern over the detr imental effects of diets high

Figure 1

Food Industry FAME Mix (cat.# 35077) resolved on an

trans

fats has prompted the US Food and Drug

Rt-2560 column.

Administra tion (FDA) to require

trans

fat content

Compound

19. C18:2

(trans-9,12)

to be reported separa tely on food labels after

1. C4:0

20. C18:2

(cis-9,12)

2. C6:0

21.C20:0

Januar y 2006. The FDA estimates that by 2009 this

3. C8:0

22. Cl8:3

(cis-6,9,12)

rule will save $900 million to $1.8 billion per year

4. CI0:0

23. C20:1

(cis-ll)

5. Cll:0

24. C18:3

(cis-9,12,15)

in medical costs and lost productivity. The mone6. C12:0

25. C21:0

tar y savings will far more than offset the FDA-esti7. C13:0

26.C20:2

(cis-ll,14)

8. C14:0

27. C22:0

mat ed $140-250 million in on e-time costs of

9. C14:1

(cis-9)

28. C20:3

(cis-8,11,14)

determ ining amounts of

tran s

fats, revising

10. C15:0

29. C22:1

(cis-B)

Nutrition Facts panels, and voluntari ly redu cing

amo unts of

trans

fats' that the food industry will

incur to comply with the rule.

The highly polar Rt-2560 biscyanopropyl station

ary phase has the selectivity needed for resolving

cis

and

trans

FAME isomers to comply with the

FDA guidelines. Individual

cis

and

trans

isomers

are resolved on a 100-meter Rt-2560 GC column

(cat.# 13199), making this the column of choice

for analyzing par tially hydrogenated fats. The

trans

isomers elute before the

cis

isomers (Figure 1), a

reverse of the elution order on Carbowax's-based

phases such as FAMEWAX™or Rtx®-Wax. AOAC

method 996.06

specifies the determination of

'-"------''--- - total fat content based on the fatty acid conte nt

30. C20:3 (cis-ll,14,17)

31. C20:4

(cis-5,8,11,14)

32. C23:0

33. C22:2

(cis-13,16)

34. C24:0

35. C20:5

(cis-5,8,11,14,17)

36. C24:1

(cis-15)

37. C22:6

(cis-4,7,10,13,16,19)

131415111920

11. Cl5:1

(cis-l0)

1324262f301"

10 11

12. Cl6:0

13. Cl6:1

(cis-9)

14. Cl7:0

15. Cl7:1

(cis-l0)

16. C18:0

17. Cl8:1

(trans·9)

18. Cl8:1

(cis-9)

after conversion of the fatty acids to the methyl

GCJF00649

Rt-2560,100m, 0.25mm 10, 0.2IJm(cat.# 13199)

Sample:

Food Industry FAMEMix(cat.# 35077),

esters, and is the accepted analytical meth od for

determining total fat con tent for nu tritional label30mg/ mL total FAMEs in methylene chloride

ing. A 100-meter Rt-2560 column meets th e

Inj.:

2.01JLsplit (split ratio 200:1), 4mminlet liner (cat.# 20814)

Inj. temp.:

225°C

requi rement s of this pro cedur e, and also allows

Carrier gas:

hydrogen, constant flow

Flow rate:

1.2mL/ min.

quantification of the total

trans

fat content.

Oven temp.:

100°C(4 min. hold)

to 240°C@ 3°C/min. (10min. hold)

To calibrate the GC system for these assays, we recDet.:

FlO @ 250°C

ommend a carefully formulated FA1\t1E mixture,

such as our 37-component Food Industry FA1\t1E

References

Mix (cat.# 35077, Figure

or our 28-componen t

http:/ / www.cfsan.fda.gov/ - dms/qatrans2.html# s5q1

NLEA FA1\t1E Mix (cat.# 35078). Each of these

'Official Methodsof Analysis,17th edition, AOAC1nternational, 2000.

mixes includes a gravime tric certificate of analysis

to help ensure accura te quantification. To ensure

correct ident ification s of individual C18:1

cis

~.-

.trans

isomers, use our

cis/trans

FAME Mix (cat.#

35079), as shown in Figure 1.

free

literature

An Rt-2560 column is the column of choice when

HighResolutionAnalyses of Fatty AcidMethyl Esters (FAMEs)

determini ng

trans

fat content and total fat content

by Gas Chromatography

in food products. Whatever your fatty acid analylit. cat.# 59584A

sis requirements, Restek can provide the consisFree on request from Restek, or from your Restek distributor.

tent -performance analytical columns and refer

ence materials that will help you to accurately

characterize your materials.

2006

vol.

• 16 •

Website :

www.chromtech.net.au

E-mail :

info@chromatech.net.au

TelNo : 03 9762 2034 . . . in AUSTRALIA