catalog coloane chirale gc

8/2/2019 Catalog Coloane Chirale GC

1/24

Inside:

Definitions of

Chirality and ChiralChromatography

Chiral ColumnsOffer UniqueSelectivity

Optimizationof ChiralSeparations

Chiral SpecificApplications ofEssential Oils,Flavors, and

Pharmaceuticals

A Guide to theAnalysis of Chiral

Compounds by GC

Technical Guide


2/24

2

The Rt-DEXsm and Rt-DEXsechiral capillary columns offer

extensive enantiomeric separationof monoterpenes, monoterpene

alcohols, and monoterpene ketonesthat cannot be matched by

permethylated -cyclodextrincolumns. Rt-DEXsp and Rt-

DEXsa are secondary columnsthat best resolve specific flavor and

fragrance chiral components. TheRt-DEXcst provides excellent

resolution of some complex flavorcompounds and has demonstrated

great potential with pharmaceuticalsubstances as well.

Index:

Definitions of Chirality andChiral Chromatography ......3

Chiral Columns OfferUnique Selectivity ...............5

Optimization of ChiralSeparations ..................... 10

Chiral Specific Applicationsof Essential Oils, Flavors, andPharmaceuticals .............. 14

A team of researchers at the

University of Neuchteldeveloped -cyclodextrins with

superb enantiomeric

selectivity. They joined forces

with Restek, a manufacturer of

top quality columns, to provide

a unique line of commercially

available -cyclodextrin

stationary phases with

enhanced capabilities for

chiral capillary gas

chromatography.

Dr. Raphael Tabacchi

Born in Ticino, Switzerland,

Dr. Tabacchi has been a

professor for Analytical and

Organic Structure at the

University of Neuchtel,

Switzerland, since 1978. His

research interests focused

upon natural product

chemistry, and development

of HPLC and GC stationary

phases. He has developed -cyclodextrins with unique

substitutions to create novel

chiral phases for capillary

GC.

Dr. Georges Claude Saturnin

Born in St. Joseph,

Martinique, Dr. Saturnin

became a Senior Assistant

and Assistant Professor in

1990 at the University of

Neuchtel. He is involved in

the development of HPLC

phases. His focus is the

synthesis of these new

cyclodextrin materials that

characterize the new chiral

columns.

Lori Bitzer

After completing her

Chemistry degree at West

Virginia University in 1995,

Lori joined Restek as a Fused

Silica Manufacturing

Chemist. She is involved with

the design and production of

new products including

capillary chiral columns. Lori

ensures product quality and

consistency that are

characteristic of all Restek

products.

Sherry Sponsler

Sherry is an Applications

Chemist and has been with

Restek since 1990. She

conducts method and product

development for analysis of

foods, flavors and fragrances,

as well as some pharmaceuti-

cal samples. Frequent

communication with

customers has helped Sherry

to identify many important

chiral applications in these

industries. She has demon-

strated many of these key

separations, especially for

fragrances and amphet-

amines, using the new

cyclodextrin capillary

columns.

Maurus Biedermann

Maurus has been with Dr.

Konrad Grobs GC/LCGC

group at the Kantonales

Laboratory Zurich (Official

Food Control Authority in

Switzerland) since 1990 and

has participated in the

development of several

LCGC methods for food

analysis. During his

sabbatical at Restek, he

demonstrated the ability of

these new and unique chiral

phases for many applications

such as the authenticity of

essential oils, natural

flavor extracts, and the

analysis of drugs for

enantiomeric composition.

Claire-Lise Porret

Born in Neuchtel, Switzer-

land, Ms. Porret was

previously a technician at

Nestl and joined Dr.

Tabacchis team in 1991. She

is also involved in the

synthesis of organic

compounds and with the

development of GC and

HPLC stationary phases.


3/24

3

Linalool is a chiral compound because it contains an assymmetric carbon

center. The mirror images are not superimposable and so they are enanti-omers.

S configuration

Enantiomers can be distinguished by configuration. Following groups from

high to low priority in the clockwise direction is denoted R, and S for the

counterclockwise direction.

R configuration

Figure 1A

Linalool oxides have two chiral centers at carbon numbers 2 and 5 and

exist as four enantiomers.

Figure 1B

2S, 5R(+)-cis-linalool oxide

2R, 5S(-)-cis-linalool oxide

2S, 5S(-)-trans-linalool oxide

2R, 5R(+)-trans-linalool oxide

WHAT ARE CHIRALCOMPOUNDS?

Any carbon atom that is bonded tofour different functional groups is

termed a chiral or an assymetric car-bon. Molecules containing one ormore of these carbon centers are con-sidered chiral molecules. Chiral cen-ters can exist in two forms calledenantiomers. These two forms arenon-superimposable mirror images ofeach other, but both have similarproperties. For example, both enan-tiomers will have the same boilingpoint, densities, and reaction rates asachiral molecules. They do, however,generally possess different aroma andflavor characteristics; more impor-

tantly, they possess differences intoxicity and biological activity.

Enantiomers are also known as opti-cal isomers because they rotate planepolarized light in different directions.

Optical isomers that rotate plane po-larized light to the right, or clockwise,are termed dextrorotary {denoted as(d) or (+)}, Optical isomers that rotatein the left direction are termed levoro-tary {denoted (l) or (-)}.

Enantiomers can be denoted by thespecific configuration around thechiral center. Groups on the carboncenter are assigned a priority basedon atomic number of the first bondedatom (Cahn-Ingold-Prelog rules). Thegroup with the highest atomic num-

ber is rated first. If priority cannot beestablished with the first atom, workoutward until priority differences canbe determined. Once priorities havebeen established for all four groups,specific configuration can be deter-

mined. An R configuration is desig-nated when the priority around theassymmetric carbon is in a clockwisedirection, whereas a counterclockwisedirection is denoted as S. (Figure 1A)1

A chiral compound can possess mul-tiple chiral centers and many combi-nations of configurations. Linalooloxides possess two chiral centers, re-sulting in four enantiomers. (Figure1B) Note that configuration (R or S) isindependent from optical activity (+ or-) or interaction with plane-polarized

light.

CH3(CH2)3CH2 CH2(CH2)3CH3CHCH2 CH2CH

OH HO

WHAT ARE CHIRAL

COMPOUNDS?

Any carbon atom that is

bonded to four different groups

is termed a chiral or an

assymetric carbon. Molecules

containing one or more of

these carbon centers are con-

sidered chiral molecules.

Chiral centers can exist in two

forms called enantiomers.

These two forms are non-

superimposable mirror imagesof each other, but both have

similar properties.


4/24

4

Figure 2Resteks chiral columns demonstrate exceptional lifetime and stability for

more than 250 injections without loss of resolution.

min. 10 20 30

min. 10 20 30

1,2

3

4

89

5

67

10 11

12

13

14

15

1,2

3

4

8

5

67

10 11

12

13

14

15

9

Chiral chromatography is the

separation of enantiomeric

compounds. Common liquid

stationary phases do not

possess adequate selectivity

for enantiomeric separation.

Addition of derivatized

cyclodextrin macromolecules

to common stationary phases

creates capillary columns with

the ability to separate

many enantiomers.

1. (-) -pinene2. (+) -pinene3. decane4. (-) 2,3-butanediol5. (+) 2,3-butanediol

30m, 0.32mm ID, 0.25m Rt-DEXsa (cat.# 13108)Oven temp.: 40C (hold 1 min.) to 230C @ 2C/min.;

Carrier gas: hydrogen; 80cm/sec. set @ 40C; Detector: FID set @ 220C

WHAT IS CHIRALCHROMATOGRAPHY?

Chiral chromatography is the separa-tion of enantiomeric compounds.

Common liquid stationary phasesused in gas chromatography resolvecomponents from one another, butthey do not possess adequate selec-tivity for enantiomeric separation.Addition of derivatized cyclodextrinmacromolecules to common station-ary phases creates capillary columnswith the ability to separate enanti-omers as well.

The permethylated derivative of beta-cyclodextrin in cyanopropyl-dim-ethylpolysiloxane liquid stationary

phase is commonly used for such ste-reochemical separations, but it exhib-its limited applications. Beta-cyclodextrins derivatized with alkylsubstituents can enhance the enan-tiomeric resolution of various com-pound classes. Resteks five capillarycolumns incorporate various combi-nations of alkylated beta-cyclodex-trins into a cyanopropyl-dimethylpolysiloxane liquid stationary phaseto achieve significant separation.

These columns also exhibit stability

and extended lifetime. From the firstinjection to the 250th injection on achiral column, enantiomeric separa-tion is maintained with almost no lossin resolution (Figures 2A and B).

A: 1st injection

B: 250th injection

6. undecane7. nonanal8. 1-octanol9. 2,6-dimethylphenol

10. (+) phenylethanol

11. (-) phenylethanol12. methyl decanoate13. dicyclohexylamine14. methyl undecanoate15. methyl dodecanoate


5/24

5

Figure 3The Rt-DEXsm column provides

the best chiral separation ofisoborneol and-terpineol.

Figure 4The Rt-DEXsm column offers

complete resolution of-ionone.

30m, 0.32mm ID, 0.25m Rt-DEXsm (cat.# 13104)Oven temp.: 40C (hold 1 min.) to 230C @ 2C/min. (hold 3 min.);


min. 30 40

(+/-) isoborneol

(+/-) terpineol

min. 30 40

-ionone

Figure 6The Rt-DEXse column resolves

limonene enantiomers.

min. 18 20

limonene

Figure 5The Rt-DEXse column resolves optical isomers of

ethyl-2-methylbutyrate, styrene oxide, and camphor

with some overlap.

min. 10 20 30

ethyl-2-methylbutyrate

styrene oxide

camphor

R S

S (-)

R (+)

30m, 0.32mm ID, 0.25m Rt-DEXse(cat.# 13106)

Oven temp.: 40C (hold 1 min.) to 230C @2C/min. (hold 3 min.); Carrier gas: hydrogen;

80cm/sec. set @ 40C; Detector: FID set @ 220C

RESTEKS CHIRAL COLUMNS OFFER UNIQUESELECTIVITY

Each of the five chiral columnsposesses a specific combination ofalkyl substituents on the derivatized-cyclodextrins. These unique combi-nations provide a wide range ofutilitization for each type of chiral

column. Table I, on page 8, indicatesthat certain columns provide betterresolution of specific compounds.

Rt-DEXsm

Of the chiral columns evaluated, onlythe Rt-DEXsm separates all of the 25tested compounds, with 19 beingbaseline resolved. This column pro-vides the best enantiomeric separa-tion of-pinene, isoborneol,-ionone,linalool oxides, hexobarbital, and me-

phobarbital (Figures 3 and 4).

Rt-DEXse

The Rt-DEXse is similar in perfor-mance to the Rt-DEXsm, but it pro-vides better resolution for limonene,linalool, linalyl acetate, ethyl-2-methylbutyrate, 2,3-butane-diol, andstyrene oxides. Sometimes extensiveseparation results in overlap of enan-tiomeric pairs, as shown in Figures 5and 6.

SR


6/24

6

Rt-DEXsm and

Rt-DEXse

Cis and trans linalool oxides, linalool,and linalyl acetate are commonlyfound together in lavender oils, andresolution of all enantiomers is desir-able. The Rt-DEXsm separates thelinalool oxides, but it does not resolvelinalyl acetate. Conversely, Rt-DEXse separates linalool and linalylacetate, but does not resolve all of thelinalool oxides. Combining both to-gether in a dual column system willprovide resolution for all of theseenantiomers (Figure 7).

Rt-DEXsp

Rt-DEXsp is a specialized columnthat best resolves menthol. It wouldbe useful in addition to the Rt -DEXsm or Rt-DEXse column foranalyzing complete profiles of mintoils (Figure 8).

Rt-DEXsa

The Rt-DEXsahas a significantly dif-ferent selectivity than the other chiralcolumns. It provides the best separa-

tion of 1-octen-3-ol, carvone, cam-phor, 1-phenylethanol, -citronellol,and rose oxides (Figure 9).

Figure 7ACis and trans linalool oxide

enantiomers separated on anRt-DEXsm column.

Figure 7BLinalool and linalyl acetate

enantiomers are resolved ontheRt-DEXse column.

Figure 8Menthol enantiomers are best resolved on the

Rt-DEXsp column.

min. 20 30

linalool oxides

30 min. 20

linalool

linalyl acetate

menthol

min. 30

Figure 9A1-octen-3-ol and carvone

enantiomers are best resolved

onan Rt-DEXsa column.

Figure 9BAn Rt-DEXsa column provides

baseline chiral resolution for-citronellol.

Figure 9CAn Rt-DEXsa column

separates racemic cis and

trans rose oxides.

1-octen-3-ol

carvone(-)(S)

(+)-c

is

(+)(R)

(+)-trans

30 40min. 20 52 53min. 51 25 26min. 24 27

(+)-trans

(+)-c

is(-)-c

is

R

S

RS

(+)(-)

(+/-)

(-)(+)

(-)-c

is

(-)-trans

30m, 0.32mm ID, 0.25m Rt-DEXsp (cat.# 13110)Oven temp.: 60C (hold 1 min.) to 200C @

2C/min.; Carrier gas: hydrogen; 80cm/sec. set @40C; Detector: FID set @ 220C

(-)-trans

30m, 0.32mm ID, 0.25m7A: Rt-DEXsm (cat.# 13104)7B: Rt-DEXse (cat.# 13106)

Oven temp.: 40C (hold 1 min.)to 230C @ 2C/min. (hold 3min.); Carrier gas: hydrogen;

80cm/sec. set @ 40C;Detector: FID set @ 220C

30m, 0.32mm ID, 0.25mRt-DEXsa (cat.# 13108)

Oven temp.: 40C (hold 1 min.)to 230C @ 2C/min. (hold 3min.); Carrier gas: hydrogen;



7/24

7

1. (+/-)-pentalactones

2. (+/-)-hexalactones3. (+/-)-heptalactones4. (+/-)-octalactones5. (+/-)-nonalactones6. (+/-)-decalactones7. (+/-)-dodecalactones

Figure 10All of the irone isomers are resolved

without overlapping of the enantiomericpairs on the Rt-DEXcst column.

Figure 11The Rt-DEXcst column provides maximumresolution of the-lactones and-lactones.

A. -lactones on the Rt-DEXcstcolumn

B. -lactoneson the Rt-DEXcstcolumn

min. 40

1. (-)-(2R,6R)-trans--irone2. (+)-(2S,6S)-trans--irone3. (+)-(2R,6R)-trans--irone4. (-)-(2S,6S)-trans--irone5. (+)-(2R,6S)-cis--irone6. (+)-(2R,6S)-cis--irone7. (-)-(2S,6R)-cis--irone8. (-)-(2S,6R)-cis--irone9. (+)-(2R)--irone

10. (-)-(2R)--irone

1

3

4

85

6

7

10

2

9

min. 100 120

1

3

4

5

2

140

1. (+/-)-heptalactones2. (+/-)-octalactones3. (+/-)-nonalactones4. (+/-)-decalactones5. (+/-)-dodecalactones

min. 100 120

1

34 5

2

140

6

7

30m, 0.32mm ID, 0.25mRt-DEXcst (cat.# 13102)

Oven temp.: 60C (hold 1 min.) to 200C@ 1C/min.; Carrier gas: hydrogen;



Oven temp.: 40C (hold 1 min.) to230C @ 2C/min. (hold 3 min.);

Carrier gas: hydrogen; 80cm/sec. set @ 40C;Detector: FID set @ 220C

Rt-DEXcst

This column is optimum for semi-volatile chiral compounds becauselower boiling components show peakbroadening (discussed in the Optimi-

zation of Chiral Separations section).All of the irone isomers (found in irisflowers) are resolved without overlap-ping of the enantiomeric pairs (Figure10). This is also the best column forresolution of the - and -lactones(Figures 11A and B).

The Rt-DEXcst column is good forseparating the enantiomers of somebarbiturates and TFA-derivatives ofamphetamines as well. This is dis-cussed in further detail on pages 22and 23.

Visit Restek on-line at

www.restek.com,

or call 800-356-1688,

ext. 4, for technical

assistance.





8/24

8

Table IResolution of common chiral compounds on Resteks cyclodextrin columns.

ns = no separation of enantiomers

t = peak tailing

b = peak broadening

ad= adsorption of nonderivatized drug compound

* = cis and trans linalool oxides analyzed @ 9.0 psi head pressure

To demonstrate the abilities of the fivedifferent types of chiral columns, weanalyzed twenty-five chiral com-pounds commonly found in flavors,fragrances, and pharmaceuticalanalyses. The extent to which two

enantiomers are resolved (or any twopeaks) can be determined by the reso-lution equation and are known asresolution factors, sometimes de-

noted R. An R value of 1.5 indicatesbaseline resolution. Resolution fac-tors for all chiral compounds on allthe -cyclodextrin columns were com-pared to those obtained on the exist-ing Rt-DEXm (permethylated

cyclodextrin) column.Table I showsthe degree of enantiomeric separationby resolution factor for all twenty-fivecomponents on each column. The col-

umn that has the largest resolutionfactor provides the best separation ofa particular compound. These valuescan easily be compared to help deter-mine which column is optimum forspecific chiral components. Charts 1

6 illustrate the degree of enantiomericseparation of each compound on eachchiral column.

Compounds Formula m.w.

Terpenes 1. -pinene C10H16 136

2. limonene C10H16 136

Alcohols 3. 1-octen-3-ol C8H16O 128

4. linalool C10H18O 154

5. -terpineol C10H18O 154

6. terpinen-4-ol C10H18O 154

7. isoborneol C10H18O 154

8. -citronellol C10H20O 156

9. menthol C10H20O 156

10. 2,3-butanediol C4H10O2 90

11. 1-phenylethanol C8H10O 122

Ketones 12. carvone C10H14O 150

13. camphor C10H16O 152

14. -ionone C13H20O 192

Lactones 15. -nonalactone C9H16O2 156

16. -undecalactone C11H20O2 184

17. -decalactone C10H18O2 170

Esters 18. ethyl-2-methylbutyrate C7H14O2 130

19. linalylacetate C12H20O2 196

Epoxides 20. styreneoxide C8H8O 120

21. trans-linalooloxides C10H18O2 170

21. cis-linalooloxides

Drugs 22. hexobarbital C12H16O3N2 236

23. mephobarbital C13H14O3N2 246

24. fenfluramine C12H16F3N 231

25. fenfluramine TFAA der. C14H15F6NO 327

Column Resolution FactorsRt-DEXsm Rt-DEXse Rt-DEXsp Rt-DEXsa Rt-DEXcst Rt-DEXm

3.50 0.80 ns ns 0.90b 3.30

5.10 7.30 3.20 ns 2.70b 1.40

1.10 ns 0.50 2.30 0.60b 0.50t

3.30 6.00 4.30b 3.70 2.60t 1.00

5.30 5.50 2.20 4.00 4.30t 1.70

2.40 2.20 ns ns 1.20t 1.80t

4.00 3.30t ns ns 1.90t 2.00

0.90 0.80 ns 1.00t ns ns

1.10 1.10 2.20 ns 1.10 1.60t

7.50 8.10 2.20 4.60 4.00 2.60

7.30 6.40 1.10 7.80 6.30 6.60

1.30 ns ns 2.50 1.10 ns

1.80 2.10t 1.30b 4.30 2.50t ns

6.40 3.20 1.30 4.40 ns 3.20

4.70 5.00 3.40 4.40 5.90 1.00

2.90 2.90 1.70 3.70 4.50 ns

0.90 ns ns 2.10 2.70 ns

1.30 3.50 1.10b ns ns ns

0.60 2.20 1.20 0.10 ns ns

4.80 10.20 6.50 1.00 1.40t 2.50t

10.10 2.40 ns 1.50 4.30b 6.80*

6.20 3.60 ns 1.00 3.50b 4.20*

11.30 4.70 0.90 ns 8.90 6.30

8.40 3.80 0.60 ns 6.20 6.10

1.80 2.90t ad ad ns ad

1.20 ns ns 2.40 3.40 ns


9/24

9

Charts 1-6 illustrate the unique separation capabilities of each cyclodextrin column.

Rt-DEXsm

12

10.5

9

7.5

6

3

1.5

0

4.5

1252 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

21

21

22

23

24

Rt-DEXse

Rt-DEXsp Rt-DEXsa

Rt-DEXcst Rt-DEXm

Compound Number*

Resolution

Factor

Compound Number*

Resolution

Factor

Compound Number*

Resolution

Factor

Compound Number*

Resolution

Factor

Compound Number*

ResolutionF

actor

Compound Number*

ResolutionF

actor

*Refer to Table I for compound identification.

12

10.5

9

7.5

6

3

1.5

0

4.5

1252 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

21

21

22

23

24

12

10.5

9

7.5

6

3

1.5

0

4.5

1252 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

21

21

22

23

24

12

10.5

9

7.5

6

3

1.5

0

4.5

1252 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

21

21

22

23

24

12

10.5

9

7.5

6

3

1.5

0

4.5

1252 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

21

21

22

23

24

12

10.5

9

7.5

6

3

1.5

0

4.5

1252 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

21

21

22

23

24


10/24

10

Figure 12BFaster linear velocities provide maximum

resolution of chiral pairs.

Figure 12AHigher Trennzahl values are obtained at 40 cm/sec

with hydrogen carrier gas.

Rt-DEXsa: 40C (80C for lactones) to 200C @2C/min. (hold 1 min.). Hydrogen carrier gas.

Rt-DEXsa: 40C to 200C @ 2C/min. (hold 1 min.).Hydrogen carrier gas.

OPTIMIZATION OFCHIRAL SEPARATIONS

Although the new-cyclodextrin col-umns can resolve a variety of chiral

compounds, certain parameters mustbe opt imized to obtain maximumseparation and column performance.Variation in linear velocity and tem-perature ramp rate can greatly affectthe resolution of enantiomers. De-pending on the type of chiral column,initial GC oven temperature can affectpeak width. Column sample capacityvaries with different compounds, andoverloading results in broad tailingpeaks and reduced enantiomericseparation.

Linear Velocity (Column Flow)

The resolution between the enantio-meric pairs can be improved by in-creasing the linear velocity. This is es-pecially important if the resolutionfactor is below two for optical isomers(see Table I). Trennzahl values aremeasurements of column separationefficiency, which are often optimumat a linear velocity of 40 cm/sec withhydrogen carrier gas. This is illus-trated in Figure 12A. Although opti-

mal linear velocity can be different foreach chiral compound and column,the typical optimum linear velocity formaximum enantiomeric separation isaround 80 cm/sec with hydrogencarrier gas, as illustrated with sixchiral compounds on the Rt-DEXsacolumn in Figure 12B. This is twicethe linear velocity required to achievemaximum efficiency as indicated bythe Trennzahl values of 1-octen-3-olenantiomers in Figure 12A.

1-octen-3-ol

linalool

-ionone

-nonalactone

-undecalactone

-decalactone

30 40 80 120

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

30 40 80 120

30

25

20

15

10

5

0

Linear Velocity (cm/sec)

TrennzahlValue

Linear Velocity (cm/sec)

Resolution

Factor


11/24

11

Figure 13BLower temperature ramp rates provide maximum

resolution of chiral pairs.

Figure 13ATrennzahl values increase with enantiomeric resolution factors as

temperature ramp rates decrease.

Rt-DEXsa: 40C (80C for lactones) to 200C @2C/min. (hold 1 min.). Hydrogen carrier gas.

Rt-DEXsa: 40C to 200C @ 2C/min. (hold 1 min.).Hydrogen carrier gas.

1-octen-3-ol

linalool

-ionone

-nonalactone

-undecalactone

-decalactone

1.5C/min.

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

5.0

5.5

2.0C/min. 2.5C/min. 3.0C/min.

30

25

20

15

10

5

0

1.5C/min. 2.0C/min. 2.5C/min. 3.0C/min.

Temperature Program

The resolution between the enantio-meric pairs can be improved by usingslow temperature ramp rates. Thebest temperature ramp rates are 1-

2C/min. Trennzahl values improvealong with enantiomeric resolution asthe temperature ramp rate is de-creased (Figures 13A and B).

Temperature Program Rate

TrennzahlValue

Temperature Program Rate

Resolution

Factor

Remember, to optimize

chiral separation use:

1) Faster linear velocities

(80 cm/sec.) with hydrogencarrier gas.

2) Slower temperature ramprates (1-2C/min.).

3) Appropriate minimumoperating temperature(40 or 60C).

4) On-column concentrationsof 50ng or less.


12/24

12

Minimum Temperature

For maximum resolution of chiralcompounds with low boiling points(below 100C), initial temperatures of35-40C are recommended for the Rt-

DEXsm, Rt-DEXse, and Rt-DEXsacolumns. In contrast, the same vola-tile compounds exhibit a very broadpeak shape on the Rt-DEXsp and Rt-DEXcst columns at these initial oventemperatures. Linalool oxides arevolatile compounds that exhibit peakbroadening and almost no resolutionon the Rt-DEXcst column with aninitial oven temperature of 40C (Fig-ure 14A). The peak shapes and over-all resolution of the linalool oxides im-prove when initial temperature isincreased to 70C, even though the in-

dividual enantiomers of both the cisand trans isomers are not separated(Figure 14B). Higher initial tempera-tures do not always completely elimi-nate peak broadening for some com-ponents. However, the improvementin solvent peak shape indicates aphysical transition of the cyclodextrinmacromolecules from a crystallinestructure to a liquid at this highertemperature. Thus the recommendedminimum operating temperature ofRt-DEXsp and Rt-DEXcst columnsis 60C.

Figure 14ALinalool oxides exhibit extreme peak broadening and poor resolution on the

Rt-DEXcst column with an initial oven temperature of 40C.

Figure 14BLinalool oxides exhibit improved peak shape and resolution on the

Rt-DEXcst column when initial oven temperature is increased to 70C.

cis & trans linalool oxides

15min. 20 25

cis & trans linalool oxides

15min. 20 25

30m, 0.32mm ID, 0.25m Rt-DEXcst (cat.# 13102)Oven temp.: 70C (hold 1 min.) to 200C @

2C/min.; Carrier gas: hydrogen; 80cm/sec. set @ 40C;Detector: FID set @ 220C

30m, 0.32mm ID, 0.25m Rt-DEXcst (cat.# 13102)Oven temp.: 40C (hold 1 min.) to 200C @

2C/min.; Carrier gas: hydrogen; 80cm/sec. set @ 40C;Detector: FID set @ 220C

Higher initial

temperatures do not

always completely elimi-

nate peak broadening

for some components.

However, the improve-

ment in solvent peak

shape indicates a physi-

cal transition of the

cyclodextrin macromol-

ecules from a crystalline

structure to a liquid at

this higher temperature.


13/24

13

Figure 15ALinalool and linalyl acetate have

symmetrical peak shapes and

excellent chiral separation on theRt-DEXse column at 25ng percomponent on-column.

linalool

min. 30 35 40

linalyl acetate

linalool

min. 30 35 40

linalyl acetate

linalool

min. 30 35 40

linalyl acetate

Figure 15CExcessive overload of chiral com-

pounds on cyclodextrin columns

results in extreme peak tailing andcomplete loss in resolution.

Figure 15BLinalool shows signs of overload

with slight peak tailing, and linalyl

acetate has a small loss inresolution when sample load is

increased to160ng.

R S

RS

RS

R

S

RS

R,S

30m, 0.32mm ID, 0.25mRt-DEXse (cat.# 13106)







Oven temp.: 40C (hold 1 min.)to 200C @ 2C/min.;Carrier gas: hydrogen;80cm/sec. set @ 40C;

Detector: FID set @ 220C

OverloadingandTailing

Some chiral compounds show over-loading at lower concentrations thanachiral compounds. One reason is thedifferent amounts of cyclodextrin (5-

50%) dissolved in the stationaryphase. Unlike the classical frontingpeaks of normal stationary phases,the characteristic of an overloadedpeak on cyclodextrin stationaryphases is indicated by a tailing peak.Overloading chiral compounds re-sults in loss of resolution, even whencolumn capacity has not been ex-ceeded. Figure 15Ashows the enan-tiomeric separations of linalool andlinalyl acetate on the Rt-DEXse. Theamount for each component in thecolumn is about 25 ng. Figure 15B

shows the same components at ahigher concentration of 160ng on-col-umn. Note that the linalool enanti-omers are beginning to tail, and thereis a small loss in chiral resolution forlinalyl acetate. Even though the maxi-mum sample capacity for 0.32mm IDcapillary columns is normally 400-500ng per component, the peakshapes of chiral compounds indicateoverload at one-third of the sampleamount. Again, there is much lesscyclodextrin for which a chiral com-pound can interact. Figure 15C

shows pronounced overloading ofthese compounds at 5g on-column.Extreme tailing and complete loss inresolution are the result.


14/24

14

CHIRAL SPECIFIC APPLICATIONS OF ESSENTIALOILS, FLAVORS, AND PHARMACEUTICALS

ESSENTIAL OILS

Chiral capillary GC has proven to be a convenient method for characterizingessential oils and differentiating natural flavors from those of synthetic origin.Chiral compounds from natural origins usually exist as one predominant op-tical isomer. Also, the inspection of enantiomeric ratios can characterize re-gional differences between oils. Although sometimes a result of processing, thepresence of racemic pairs (one-to-one ratios of each enantiomer) most oftenindicates adulteration or unnatural origin.

Since most chiral compounds natu-rally exist as one predominant isomer,resolution is more challenging, espe-cially for components in higher con-centrations. For primary constituentsin essential oils, select a chiral col-

umn that provides a resolution factorvalue greater than two to overcomepossible loss of resolution.

Since essential oils are mixtures ofmany compounds, coelution of peaksand overlapping of certain opticalpairs are sometimes hard to avoid.Not all of the chiral compounds foundin an essential oil or flavor extract mayseparate on the same column. Con-necting two different columns to-gether is possible, but the elution or-der of some enantiomers may reverse

with this combination, resulting inloss of separation. Dual columnanalysis is a logical alternative to ob-tain a more complete enantiomericprofile and to provide confirmationalidentification of individual constitu-ents. To reduce analysis time, bothcolumns can be installed into thesame injection port for simultaneousconfirmation. (Consult Resteks Chro-matography Products Guide for moreinformation about dual columnanalysis.)

For primary constituents

in essential oils, select

a chiral column that

provides a resolution

factor value greater than

two to overcome possible

loss of resolution.


15/24

15

Lemon Oil

TheRt-DEXsmis the optimum col-umn for obtaining chiral profiles ofLemon and other citrus oils since itprovides enantiomeric separation for

the main terpene constituents like -and -pinenes, sabinene (these enan-tiomers overlap with those of -pinene) and limonene (Figure 16).

Rosemary Oil

Chiral constituents in this oil include-pinene, -pinene, camphene, li-monene, linalool, camphor, terpinen-4-ol, -terpineol, borneol, andisoborneol. Baseline enantiomericseparation is easily achieved for all ofthese compounds on the new Rt-DEXsm column. The commonpermethylated-cyclodextrin columncannot completely resolve the optical

isomers of limonene, linalool, andcamphor (Figure 17).

Figure 17The Rt-DEXsm, the most versatile-cyclodextrin column for essential oil

analysis, resolves enantiomers of-pinene, -pinene, camphene, limonene,

linalool, camphor, terpinen-4-ol, -terpineol, borneol, and isoborneol inrosemary oil.

10 020.nim

1

30 40

2

3

3

4

4 1. (-/+)-pinene2. (+/-)camphene3. (+/-)-pinene4. (-/+)limonene5. eucalyptol (cineole)6. linalool7. camphor8. (-/+)terpinen-4-ol9. isoborneol

10. borneol11. -terpineol

66

7

7

8

899 10

10

1111

5

30m, 0.32mm ID, 0.25m Rt-DEXsm (cat.# 13104);Oven temp.: 40C (hold 1 min.) to 200C @ 2C/min. (hold 3 min.);

Carrier gas: hydrogen; 80cm/sec.; Detector: FID set @ 220C

Figure 16The Rt-DEXsm column provides chiral resolution of the primary

terpenes in Artificial Lemon oil.

15min. 10 20 25

1

30 35 40 45

1

2

2

3

3

44

1. (-/+)-pinene2. sabinene3. (+/-)-pinene4. (-/+)limonene



The Rt-DEXsm is the

optimum column for

obtaining chiral profiles

of Lemon and other

citrus oils.


www.restek.com,

or call 800-356-1688,


assistance.


16/24

16

Figure 18The Rt-DEXsm column is optimumfor the separation of (+/-) - and

-pinene, limonene, and menthonein peppermint oil.

Figure 19AAnalyze spearmint oil on theRt-DEXsm column to obtain

maximum separation of (+/-) -and-pinene, limonene, and

menthone enantiomers.

15min. 10 20 25 30 35 40 45

1

2

3

3

4

1. (-/+) -pinene2. (+/-) -pinene3. (-/+) limonene4. (+/-) menthone5. (+/-) menthol (no sep.)

5

{

{

{

15min. 10 20 25 30 35 40 45

1. -pinene2. -pinene

3. limonene4. menthone5. menthol (no sep.)6. carvone (no sep.)

1

2

33

4

5

{

{

{

6

Figure 19BThe optical isomers of carvone best

separate on the Rt-DEXsa column.

30m, 0.32mm ID, 0.25m Rt-DEXsm (cat.# 13104); Oven temp.: 40C (hold 1 min.) to200C @ 2C/min. (hold 3 min.); Carrier gas: helium; 60cm/sec.; Detector: MSD set @ 220C

30m, 0.32mm ID, 0.25m Rt-DEXsm (cat.# 13104); Oven temp.: 40C (hold 1 min.) to200C @ 2C/min. (hold 3 min.); Carrier gas: helium; 60cm/sec.; Detector: MSD set @ 220C

MidwesternSpearmint

(d)

(l)

RacemicCarvoneStandard

(d)(l)

min. 38 39 40

30m, 0.32mm ID, 0.25m Rt-DEXsa(cat.# 13108); Oven temp.: 40C

(hold 1 min.) to 200C @ 2C/min.;Carrier gas: helium; 60cm/sec. set @ 40C;

Detector: MSD set @ 220C

Peppermint Oil providedby AM Todd.

Spearmint Oil providedby AM Todd.

Peppermint Oil

The Rt-DEXsm column is optimum for the separation of (+/-) - and -pinene,limonene and menthone. Since menthone and menthol enantiomers are ma-jor constituents of peppermint oil, reducing the sample size to prevent over-loading of these components and provide better enantiomeric resolution may

be necessary.

An alternative solution is to use an Rt-DEXsp as a secondary column since itprovides better resolution of menthol. However, do not use this column in adual column system with an Rt-DEXsm. The minimum temperatures of thesephases differ by 20C, which would minimize volatile terpene separation onthe Rt-DEXsm (Figure 18).

Spearmint Oil

The Rt-DEXsm column yields maxi-mum separation of (+/-) - and -pinene, limonene and menthoneenantiomers in spearmint oil. The

enantiomeric ratios of the primarychiral constituents in an artificialspearmint oil can be seen in the chro-matogram shown in Figure 19A.

Al though the op tical isomers ofcarvone best separate on the Rt-DEXsa column, -pinene and li-monene do not. For the separation ofcarvone, use a dual column systemcomprised of 30-meter Rt-DEXsmand Rt-DEXsa columns, since bothhave a minimum operating tempera-ture of 40C. Figure 19B compares

carvone in natural sources of spear-mint oil to a racemic standard on theRt-DEXsa column.

min. 38 39 40


17/24

17

Figure 20ALinalool and linalool oxides in lavender oils are stereochemically

separated on the Rt-DEXsm column.

Figure 20BTheRt-DEXse column resolves enantiomers of

linalyl acetate in lavender oils.

20 05040301.nim

20 05040301.nim

1a. (-)-limonene1b. (+)-limonene2. (+)-trans-linalool oxide3. (-)-cis-linalool oxide

4a. (-)- (R)-linalool4b. (+)-(S)-linalool5. (+/-)camphor6. R,S linalyl acetate

1b

2 3

4a

5{

6

1a

Lavender oils provided by Belmay.

Lavender oils provided by Belmay.

30m, 0.32mm ID, 0.25m Rt-DEXse (cat.# 13106);Oven temp.: 40C (hold 1 min.) to 200C @ 2C/min. (hold 3 min.);




1a. (-)-limonene1b. (+)-limonene2. (+)-trans-linalool oxide3. (-)-cis-linalool oxide

4a. (-)- (R)-linalool4b. (+)-(S)-linalool5. (+/-)camphor

6a. (-)-(R)-linalyl acetate6b. (+)-(S)-linalyl acetate

1a

1b

+

eucalyptol

2 3

4a

{5

6a6b


www.restek.com,or call 800-356-1688,


assistance.

Lavender Oil

The Rt-DEXsm column separatesthe enantiomers of the primary chiralcompounds found in lavender oil, in-cluding linalool. Both the cis and

trans enantiomeric pairs of thefuranoid linalool oxides, which con-tribute characteristic odors to laven-der oils and Clary sage oil, are sepa-rated on this column. (R)-Linalool ispresent in at least 85% enantiomericexcess. (2R)-Configured linalool ox-ides are present in about 77% enan-tiomeric excess in authentic Lavenderoils.2 Both the cis and trans (R)-lina-lool oxides are essentially enantio-merically pure in this oil, as shown inFigure 20A(peaks 2 and 3).

Linalyl acetate is another primaryconstituent in lavender oils. The (R)-(-) enantiomer is predominant in au-thentic lavender oils.3 A dual columnsystem comprised of both the Rt-DEXsm and Rt-DEXse columnscan be used to resolve the enanti-omers of linalyl acetate as well (peak6 in Figure 20B). Note that the (-)-(R)-enantiomer constitutes >92% oflinalyl acetate in this lavender oil.

4b

4b


18/24

18

6b

7

1a. (+)-(2R,4S)-cis-rose oxide1b. (-)-(2S,4R)-cis-rose oxide2a. (-)-(2R,4R)-trans-rose oxide2b. (+)-(2S,4S)-trans-rose oxide3. isomenthone4. menthone

5a. (-)-(R)-linalool5b. (+)-(S)-linalool6a. (-)-(S)--citronellol6b. (+)-(R)--citronellol7. geraniol8. citronellyl formate

Figure 21AThe Rt-DEXsa column provides chiral resolution for cis and trans rose

oxides, linalool, and-citronellol in Chinese Geranium oil.

Figure 21BThe Rt-DEXsa column reveals authenticity of Rose oil Maroc.

1a

40 060503.nim

40 060503.nim

1b

2a2b

3

4

5a 5b

6a

8

1. (-)-(2S,4R)-cis-rose oxide2. (-)-(2R,4R)-trans-rose oxide

3a. (-)-(R)-linalool3b. (+)-(S)-linalool4. phenylethyl alcohol

5a. (-)-(S)--citronellol5b. (+)-(R)--citronellol6. geraniol

6

1

2

3a

4 5a

5b

3b

Geranium oils provided by Belmay.

30m, 0.25mm ID, 0.25m Rt-DEXsa (cat.# 13109);Oven temp.: 60C to 110C @ 1C/min. (hold 30 min.);


30m, 0.25mm ID, 0.25m Rt-DEXsa (cat.# 13109);Oven temp.: 60C to 110C @ 1C/min. (hold 30 min.);


Geranium Oil

Chiral constituents in geranium oilsinclude cis and trans rose oxides,linalool, and -citronellol. The Rt-DEXsa column provides chiral reso-

lution for all of these compounds. Inauthentic samples of geranium oil,(-)-(4R)-configured diastereomers ofcis- and trans-rose oxides predomi-nate over their (+)-enantiomers.3 The(-)-(S) form of-citronellol is 74-80%of the enantiomeric ratio.4 Note thatcis- and trans-rose oxides and -cit-ronellol are racemic in this particu-lar commercial geranium oil, asshown in Figure 21A. These racemiccompounds indicate that this oil isnot authentic.

Rose Oil

As with geranium oils, (-)-(2S,4R)-cisand (-)-(2R,4R)-trans rose oxides and(-)-(S)--citronellol are specific indica-tors of genuine rose oils.5 Note theenantiomeric purity of these com-pounds in Rose Oil Maroc, as shownin Figure 21B.


www.restek.com,

or call 800-356-1688,


assistance.


19/24

19

Figure 22The Rt-DEXse column can differentiate Bergamot extract

from Bergamot flavor.

(R)-limonene

13min. 8 18

(R)-lina

loo

l

(R)-lina

lylace

tate

(R)-lina

loo

l

(R)-limonene

(R)-lina

lylace

tate

13min. 8 18

(S)-lina

loo

l

(S)-limonene

(S)-lina

lylace

tate

30m, 0.32mm ID, 0.25m Rt-DEXse (cat.# 13106);Oven temp.: 40C (hold 1 min.) to 200C @ 4C/min.;

Carrier gas: helium; 60cm/sec. set @ 40C; Detector: MSD set @ 220C

FLAVORS

Bergamot oil and a few of the popularfruit flavorings such as raspberry,strawberry, and peach were exam-ined. The composition of extracts from

natural sources were compared tothose from commercially available fla-vored teas and drinks. Some targetchiral compounds examined werelinalool and linalyl acetate in berga-mot oil, -ionone and -decalactone inraspberry, and -lactones in peach

extracts.

Bergamot Flavor

A genuine cold-pressed bergamot oilshould contain only the (R)-isomers oflinalool and linalyl acetate.6 The enan-tiomeric purity of (R) limonene shouldalso be considered.7 Chromatogram Ain Figure 22 is a natural source ofbergamot oil . Only the (R)-enanti-omers of limonene, linalool and linalylacetate were present. ChromatogramB illustrates an extract from an arti-ficially flavored tea. Both sampleswere analyzed on an Rt-DEXse col-umn. The presence of racemic linalooland linalyl acetate indicates bergamotflavor of unnatural origin.

A: Bergamot Extract

B: Bergamot Flavor

(S)-limonene


20/24

20

Figure 23The-lactones are analyzed for the adulteration of

peach flavor on the Rt-DEXsa column.

190 min. 38

-d

eca

lac

tone

-d

odeca

lac

tone

R

R

S+

30m, 0.32mm ID, 0.25m Rt-DEXsa (cat.# 13108); Oven temp.: 60C (hold 2 min.)to 100C @ 15C/min., then to 220C @ 3C/min.;

Carrier gas: helium; 60cm/sec. set @ 60C; Detector: MSD set @ 220C.

-u

ndeca

lac

tone

R

-u

ndeca

lac

tone

R S

R

-d

eca

lac

tone

-o

ctalac

tone

R S

Peach Flavor

Both - and -lactones are present inpeaches, but only the -lactones areanalyzed for the adulteration of peachflavor. Gamma-decalactone occurs in

the 89% (R) : 11%(S)- enantiomers innatural Peach flavor.8 In Figure 23,Chromatogram A is a peach extract.A signif icant amount of the (R)--decalactone was present, along withthe (S)-enantiomer, which coelutedwith an unknown. A small amount of(R)--dodecalactone was also de-tected. Chromatogram B is an extractfrom a beverage with all naturalpeach flavor. Gamma-decalactonewas no t present, but racemic -undecalactone was found in a 1:1 ra-tio. This was the same result with an-

other peach-flavored beverage.Chromatogram C is from an all natu-ral-flavored beverage, with peachand vanilla flavors. Although only the(R)-enantiomer of-decalactone waspresent, the amount is very small.Both -octalactone and -undecalac-tone were found to be racemic, indi-cating adulteration.

A: Peach Extract

B: Peach Flavor

C: Peach/Vanilla Flavor

The-lactones are

inspected for the

adulteration of

peach flavor.

S


21/24

21

Raspberry Flavor

Alpha-ionone from raspberries occursas an enantiopure (R)(+)-enantiomer,illustrated on an Rt-DEXsa columnin Figure 24A. Chromatogram B rep-

resents anaturally flavored rasp-berry iced tea. A racemic mixture of-ionone was present, indicating thatit is not a completely natural rasp-berry flavor. Thus, -ionone serves asa good marker compound for deter-mining raspberry authenticity.

Figure 24The Rt-DEXsa column resolves isomers of-ionone to

determine raspberry authenticity.

-i

onone

20min. 10 30

-i

ono

ne

-d

eca

lac

tone

R

R

S

S

40

20min. 10 30 40

30m, 0.32mm ID, 0.25m Rt-DEXsa (cat.# 13108);Oven temp.: 60C (hold 2 min.) to 200C @ 3C/min.;


-i

onone

A: Raspberry Extract

B: Raspberry Flavor

Alpha-ionone serves as a

good marker compound

for determining

raspberry authenticity.

30m, 0.32mm ID, 0.25m Rt-DEXsa (cat.# 13108);Oven temp.: 60C (hold 2 min.) to 200C @ 3C/min.;



22/24

22

Figure 25The optical isomers of TFA-fenfluramine and its metabolite are

well resolved on the Rt-DEXcst column.

Figure 26The Rt-DEXcst column can resolve the enantiomers of

common barbiturates.

20min. 15 25 30 35 40

20min. 10 30 5040

Figure 27The Rt-DEXcst column simultaneously resolves the enantiomers of

TFA-amphetamine and TFA-methamphetamine.

12min. 10 14 16 18 20 22 24

30m, 0.32mm ID, 0.25mRt-DEXcst (cat.# 13102);

Oven temp.: 60C (hold 1 min.) to220C @ 3C/min.; Carrier gas:hydrogen; 80cm/sec. set @ 60C;

Detector: FID set @ 220C.

30m, 0.32mm ID, 0.25mRt-DEXcst (cat.# 13102);

Oven temp.: 90C (hold 1 min.) to200C @ 2C/min. (hold 3 min.);

Carrier gas: hydrogen; 80cm/sec. set@ 60C; Detector: FID set @ 220C.

(+)-fen

fluramine

(-)-fen

fluram

ine

(+)-norfen

fluram

ine

(-)-nor

fen

fluram

ine

(+/

-)-h

exo

barb

ita

l

(+/

-)-m

ep

ho

barb

ita

l

30m, 0.25mm ID, 0.25m Rt-DEXcst (cat.# 13103); Oventemp.: 120C (hold 1 min.) to

175C @ 1.5C/min.; Carrier gas:helium; 25cm/sec. set @ 120C;

Detector: MSD set @ 220C.

me

thamp

he

tam

ine

amp

he

tam

ine

DRUGS

Stereochemical properties of chiraldrugs have been found in many in-stances to be the controlling factorconcerning activity. One enantiomer

may provide a biological function. Theother may be inactive or exhibit an-other functionality, which could re-sult in side effects. In some cases, oneoptical isomer may be harmful. TheFDA requires drug manufacturers totest the individual enantiomers ofnew drugs for toxicity.

Fenfluramine

Fenfluramine is an appetite suppres-sant to promote weight loss with

obese patients.9 Although it is struc-turally similar to amphetamines, itdiffers somewhat pharmacologically.Norfenfluramine is a metabolite thatis found in urine and serum of pa-tients. The purpose of the chiral iso-lations, like many analyses in thepharmaceutical industry, is of propri-etary nature. The TFA derivatives ofboth fenfluramine and norfenflur-amine are separated into their enan-tiomers on the Rt-DEXcst column(Figure 25).

Barbiturates

Mephobarbital and Hexobarbital arebarbiturates with sedative, hypnoticand anticonvulsant properties.10 Be-cause psychological and physical de-pendence may occur with continuinguse, they are controlled substances inthe U.S. Code of Federal Regulations.The optical isomers of these barbitu-rates can be simultaneously resolvedon an Rt-DEXcst column (Figure26).

Amphetamines

Dextroamphetamine (d-amphet-amine), d,l-amphetamine, and d-methamphetamine are sympathomi-metic amines with central nervoussystem stimulant activity.11 They aresignificant drugs of abuse in theUnited States and are includedamong the drugs to be tested under

(+)

(-)

(+) (-)


23/24

23

1. John McMurray, Organic Chemistry, Brooks/Cole Pub., Monterey, CA, 1984.2. C. Askari and A. Mosandl, Phytochem. Anal., Vol.2 p.211 (1991).3. Uzi Ravid, Eli Putievsky, and Irena Katzir, Chiral Analysis of Enantiomerically pure (R)-(-) Linalyl

Acetate in some Lamiaceae, Myrtle, and petigrain Essential Oils,Flavour Fragrance J.Vol.9,Pp. 275-276 (1994).

4. Peter Kreis and Armin Mosandl, Chiral Compounds of Essential Oils. Part XIII. SimultaneousChirality Evaluation of Geranium Oil Constituents.Flavour and Fragrance Journal, Vol. 8. Pp.161-168. (1993).

5. Peter Kreis and Armin Mosandl, Chiral Compounds of Essential Oils. PartXII. AuthenticityControl of Rose Oils, Using Enantioselective Multidimensional Gas Chromatography.Flavourand Fragrance Journal, Vol. 7, Pp. 199-203 (1992).

6. W.A. Konig, C. Fricke, and Y. Saritas, Adulteration or Natural Variability? Enantiomeric GC inPurity Control of Essential Oils. University of Hamburg, Institute of Organic Chemistry.

7. H.P Neukum and D.J. Meier, Detection of Natural and Reconstituted Bergamot Oil in Earl Grey

Teas by separation of the Enantiomers of Linalool and Dihydrolinalool, Mitt. Gebiete Lebensm.Hyg., Vol. 84, Pp. 537-544 (1993).

8. Anna Artho and Konrad Grob, Determination of-Lactones Added to Foods as Flavors. How FarMust Nature-Identical Flavors be Identical with Nature ?, Mitte. Gebiete Lebensm. Hyg. Vol. 81,Pp. 544-558 (1990).

9. Physicians Desk Reference, 46th ed., Pp. 1867-1868 (1992).10. Physicians Desk Reference, 46th ed., Pp. 2061-2062 (1992).11. Physicians Desk Reference, 46th ed., Pp. 514-515 (1992).12. W. Haefely, E. Kyburz, M. Gerecke, and H. Mohler. Recent Advances in the molecular

pharmacology of bezodiazepine receptors and in the structure-activity relationships of theiragonists and antagonists.Adv. Drug Res.Vol. 14, Pp. 165-322 (1985).

13. J.T. Cody and R. Schwartzhoff, Interpretation of Methamphetamine and AmphetamineEnantiomer DataJ. Anal Toxicol. Vol. 17, Pp. 321-326 (Oct. 1993).

PRODUCT LIST

Rt-DEXsm (30m, 0.25m) Rt-DEXse (30m, 0.25m)

mm ID cat.# min. temp. max. temp. mm ID cat.# min. temp. max. temp.

0.25 13105 40C 230C 0.25 13107 40C 230C

0.32 13104 40C 230C 0.32 13106 40C 230C

Rt-DEXsa (30m, 0.25m) Rt-DEXsp (30m, 0.25m)

0.25 13109 40C 230C 0.25 13111 60C 230C

0.32 13108 40C 230C 0.32 13110 60C 230C

Rt-DEXcst (30m, 0.25m) Rt-DEXm (30m, 0.25m)

0.25 13103 60C 230C 0.25 13100 40C 230C

0.32 13102 60C 230C 0.32 13101 40C 230C

Stereochemical proper-

ties of chiral drugs have

been found in many in-

stances to be the control-

ling factor concerningactivity. One enantiomer

may provide a biological

function and the other

may be inactive or may

exhibit another function-

ality, which could result

in side effects.

the federal guidelines for workplacedrug testing.12 However, l-metham-phetamine (deoxyephedrine) is foundin over-the-counter decongestantsand is not a controlled substance.13

Enantiomeric separation of these

compounds, which is necessary foraccurate interpretation of drug tests,is easily achieved on the Rt-DEXcstchiral capillary GC column (Figure27).


24/24

PATENTS & TRADEMARKS

Restek patents and trademarks arethe property of Restek Corporation.Other trademarks appearing in

Restek literature or on its websiteare the property of their respectiveowners.

Restek U.S. 110 Benner Circle Bellefonte, PA 16823 814-353-1300 800-356-1688 fax: 814-353-1309 www.restek.com

Restek France phone: +33 (0)1 60 78 32 10 fax: +33 (0)1 60 78 70 90 e-mail: [email protected]

Restek GmbH phone: +49 (0)6172 2797 0 fax: +49 (0)6172 2797 77 e-mail: [email protected]

Lit. Cat.# 59889 1997 Restek Corporation.

catalog coloane chirale gc

Documents