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Hot Topics in Analytical & Chromatography - August 2009
In this issue, we address the following topics:
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 Helium Shortage - With recent disturbances in the worldwide availability of helium, GC analysts may wish to consider whether hydrogen should be their carrier gas choice.
In addition to decreased costs, the use of hydrogen as a carrier gas also results in increased speed when compared to helium, as shown in the chromatograms below.
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Helium carrier gas at 20 cm/sec, constant |
Hydrogen carrier gas at 45 cm/sec, constant
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| Peak IDs |
| 1. |
Naphthalene |
| 2. |
Acenaphthylene |
| 3. |
Acenaphthene |
| 4. |
Fluorene |
| 5. |
Phenanthrene |
| 6. |
Anthracene |
| 7. |
Fluoranthene |
| 8. |
Pyrene |
| 9. |
Benzo(a)anthracene |
| 10. |
Chrysene |
| 11. |
Benzo(b)fluoranthene |
| 12. |
Benzo(k)fluoranthene |
| 13. |
Benzo(a)pyrene |
| 14. |
Indeno(1,2,3-cd)pyrene |
| 15. |
Dibenzo(a,h)anthracene |
| 16. |
Benzo(g,h,i)perylene |
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| Conditions |
| Column: |
Equity-5, 15 m x 0.10 mm I.D., 0.10 µm (28083-U) |
| Oven: |
100 °C (1 min.), 35 °C/min. to 325 °C (5 min.) |
| Inj.: |
250 °C |
| Det.: |
FID, 350 °C |
| Injection: |
1 µL, 200:1 split |
| liner: |
4 mm I.D., split, cup design |
| Sample: |
each analyte at 200 ppm in methylene chloride |
Additional Information:
- The full benefits (increased speed and decreased cost) plus safety considerations of switching from helium to hydrogen are detailed in Application Note 184 (206Kb PDF).
- Features, benefits, capacities, and requirements of several makes/models of hydrogen gas generators can be found in the Gas Generators Brochure (435Kb PDF).
- Practical considerations, theoretical discussions, a listing of columns in Fast GC dimensions, multiple chromatograms, plus a list of literature for additional reading can be found in the Fast GC Brochure (2.5Mb PDF).
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 Resveratrol by SPME-GC - Recent research suggests that the consumption of resveratrol, found in red wine, may reduce the risk of certain cancers, heart disease, and other age-related disorders.
The ability of SPME-GC to perform the extraction, derivatization, and analysis of resveratrol spiked in red wine was investigated, with the resulting chromatography displayed below.
Resveratrol extraction and derivatization was carried out on a polyacrylate SPME fiber. Separation was performed on the SLB-5ms capillary GC column.
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Analysis of Resveratrol in (Spiked) Red Wine |
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| Peak IDs |
| 1. |
cis-Resveratrol |
| 2. |
trans-Resveratrol |
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| Conditions |
| Sample/matrix: |
3 mL of red wine (California merlot) spiked with resveratrol at 100 µg/L then diluted 3:1 in 12% ethanol:water |
| SPME fiber: |
85 µm polyacrylate |
| Extraction: |
Immersion for 15 min. at room temperature while stirring at 400 rpm, fiber gently blotted with a Kimwipe to remove excess water, then derivatization by immersion in a 4 mL vial containing 5 µL of Sylon-BFT (fresh vial for each analysis that was allowed to equilabrate 60-90 minutes prior to use) for 20 min. |
| Desorption process: |
280 °C for 2 min. |
| Column: |
SLB-5ms; 30 m x 0.25 mm I.D., 0.25 µm (28471-U) |
| Oven: |
100 °C (1 min.), 10 °C/min. to 325 °C (3 min.) |
| MSD interface: |
325 °C |
| Scan range: |
m/z 40-450 |
| Carrier gas: |
helium, 1 mL/min., constant |
| liner: |
0.75 mm I.D., SPME |
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 Melamine by GC - Melamine contamination in food has become an issue in recent years after the discovery of its presence and that of related compounds in pet food and baby formula.
The applicability of the SLB-5ms GC column for the US Food and Drug Administration method was investigated. The resulting chromatogram for spiked dog food is shown below.
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Melamine and Related Compounds in (Spiked) Dog Food on the SLB-5ms Capillary GC Column |
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| Peak IDs |
| 1. |
Cyanuric acid |
| 2. |
Ammelide |
| 3. |
2,6-Diamino-4-chloropyrimidine (I.S.) |
| 4. |
Ammeline |
| 5. |
Melamine |
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| Conditions |
| Column: |
SLB-5ms; 30 m x 0.25 mm I.D., 0.25 µm (28471-U) |
| Oven: |
115 °C (3 min.), 10 °C/min. to 325 °C (6 min.) |
| Inj.: |
250 °C |
| MSD interface: |
325 °C |
| Scan range: |
SIM |
| Carrier gas: |
helium, 1 mL/min., constant |
| Injection: |
1 µL, splitless |
| Liner: |
4 mm I.D. single taper |
| Sample: |
TMS derivatives of melamine and related compounds (extract of dog food spiked with each analyte at 10 µg/g, with I.S. added at 1000 ng/mL, in pyridine:sylon BFT) |
Additional Information:
- Method information was obtained from “GC-MS Screen for the Presence of Melamine, Ammeline, Ammelide and Cyanuric Acid” US FDA Laboratory Information Bulletin No. 4423, October 2008
- Additional information concerning the SLB-5ms line of columns can be found at sigma-aldrich.com/slb
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