ADV06-15_1-412

• 21 •

2008 vol. 3

Option 2: Comprehensive PGI Method

Although the thin film Rxi®-5Sil MS column allows for fast analysis of sul-

fonate esters, the smaller, more polar alkyl halides are not well retained. To

take advantage of the halogen constituents on the alkyl halides, a thick film

Rtx®-200 column was used to develop a comprehensive method for both

volatile alkyl halides and less volatile sulfonate esters. Since the Rtx®-200 col-

umn has a fluorinated stationary phase, the alkyl halides are well-retained

(Figure 3). Note that all of the alkyl halides elute at a low temperature and

some of the more volatile compounds elute prior to the sample solvent (ace-

tonitrile). Because of this, the solvent cut time must be carefully measured.

The Rtx®-200 column is also selective for sulfonate esters, providing baseline

resolution for 20 out of 22 of the compounds analyzed (Figure 4). Additionally,

the increased polarity of the fluorinated Rtx®-200 phase allows for the use of

splitless injection of more polar sample solvents, such as methanol.

Conclusion

Since potential genotoxic impurities are of increasing concern for both regu-

latory bodies and consumers, the importance of effective methods for detec-

tion and quantitation of these compounds is growing. As a result of collabo-

ration between Merck and Restek, two easy, sensitive options are now avail-

able for the analysis of PGIs in API using inert, selective columns from Restek.

Figure 3

Small, polar alkyl halides are well-retained on the fluorinated Rtx®-200 column, as are less volatile sulfonate esters.

Product Listing

Rtx®-200 Columns (fused silica)

(Crossbond

trifluoropropylmethyl polysiloxane)

ID df (µm)

temp. limits

length cat. #

price

0.18mm 0.20 -20 to 310/330°C 20-Meter 45002

0.25mm 1.00 -20 to 290/310°C 30-Meter 15053

Get More!

For more information on these

methods, visit us online:

www.restek.com/pgimethods

1. 1-chloropropane

2. bromoethane

3. 2-chloropropane

4. 1-bromopropane

5. 2-bromopropane

6. 1-bromobutane

7. dimethyl sulfate (DMS)

8. methyl methanesulfonate (MMS)

9. ethyl methanesulfonate (EMS)

10. isopropyl methanesulfonate (iPMS)

11. diethyl sulfate (DES)

12. di-isopropyl sulfate (DPS)

13. di-

-propyl sulfate (DNS)

14. dibutyl sulfate (DBS)

15. methylbenzene sulfonate (MBS)

16. ethylbenzene sulfonate (EBS)

17. methyl toluenesulfonate (MTS)

18. ethyl toluenesulfonate (ETS)

19.

-butyl benzenesulfonate (nBBS)

20.

-propyl toluenesulfonate (nPTS)

21. isopropyl toluenesulfonate (iPTS)

22.

-butyl toluenesulfonate (nBTS)

*ortho isomer of ETS

Column:

Rtx

-200, 30m, 0.25mm ID, 1.0µm (cat.# 15053)

Sample:

100µg/mL each compound in 90:10 acetonitrile:water

Inj.:

1µL, split (10:1), 4mm single gooseneck inlet liner w/ wool (cat.# 22405)

Inj. temp.:

220°C

Carrier gas:

helium, constant flow

Flow rate:

1.0mL/min.

Oven temp.:

40°C (hold 8.3 min.) to 70°C @ 70°C to 115°C @ 40°C to

250°C @ 30°C to 300°C @ 15°C (hold 3 min.)

Det:

Transfer line temp.: 280°C

Scan range:

20-250m/z

Ionization:

Mode:

scan

GC_PH01076

Rxi®-5Sil MS Columns (fused silica)

(Crossbond®, selectivity close to 5% diphenyl/95% dimethyl

polysiloxane)

ID df (µm)

temp. limits

length cat. #

price

0.18mm 0.18 -60 to 330/350°C 20-Meter 43602

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