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New Wool Ensures More Accurate Semivolatiles Analyses


By Scott Grossman, Innovations Chemist

  • Lower detection limits for 2,4-dinitrophenol with new wool for semivolatiles.
  • Improve data accuracy with complete sample transfer.
  • Extend column lifetime by reducing matrix contamination.

Ensuring success for semivolatiles analysis is dependent on several issues. The column is an important factor; however, even with a high performance column, other parameters can significantly impact final results. Liner choice is one of the most important noncolumn factors that affects end data and to take full advantage of the column's performance the analytes need to reach the column without degradation or discrimination. How much of the sample is transferred, how reproducible the transfer is, and how representative the data will be of the original sample are all influenced by injection port factors. In this article, we will demonstrate how liners with Semivolatiles Wool—a new wool, specifically designed for semivolatiles analysis—can be used to optimize the injection port for more complete sample transfer, increased accuracy, and lower detection limits.

For semivolatiles analysis, many analysts operate their inlets in the splitless mode using a single gooseneck liner to protect the vaporized sample cloud and prevent analyte breakdown during the relatively long dwell time in the hot injection port. Wool can be used in the liner to promote sample vaporization, minimize molecular weight discrimination, improve chromatography, and extend column lifetime by preventing matrix contaminants from entering the column. However, wool must be chosen with care as some types may have active sites, which can interact with target analytes and negatively affect both peak shape and response. For example, some active phenolic compounds, such as 2,4-dinitrophenol (DNP), can be completely adsorbed and not detected at all, depending on the wool that is used.

Restek's new Semivolatiles Wool was developed specifically for semivolatiles analysis. Liners with Semivolatiles Wool were compared to MS Certified Liners packed with wool, and the Semivolatiles Wool liners were found to have greater response for 2,4-dinitrophenol, allowing it to be detected at much lower levels (Figure 1). Semivolatiles Wool liners also demonstrated greater inertness through consistent results in initial analyses, i.e., very little priming was observed (Table I). While inertness was initially tested using a flame ionization detector (FID), results for mass spectrometry (MS) were also excellent (Figure 2). More than twice the required response factor for 2,4-dinitrophenol was routinely achieved when analyzing just 1ng on-column by MS (Figure 3).

An inert sample pathway allows complete sample transfer and using Semivolatiles Wool liners is key to ensuring accurate, reproducible semivolatiles data when using a wool-packed liner. This new wool outperforms analogous MS Certified Liners and can help extend column lifetime and lower detection limits for active semivolatile compounds.

Figure 1  Active compounds, such as 2,4-dinitrophenol, can be seen at lower levels with Restek's Semivolatiles Wool liners.

1. 3-Nitroaniline
2. 2,4-Dinitrophenol
3. Pentachlorophenol
4. Phenanthrene
Comparison of 2,4-Dinitrophenol response with Semivolatiles wool and MS Certified wool
Column Rxi®-5Sil MS, 30 m, 0.25 mm ID, 0.25 µm (cat.# 13623)
Sample Phenols/Anilines/Pesticides Test Mix (cat.# 35245)
Conc.: 10 ng on-column
Inj. Vol.: 1.0 µL splitless (hold 0.75 min.)
Liner: Gooseneck Splitless (4mm) w/Semivolatiles Wool (cat.# 20798-231.1)
Inj. Temp.: 250 °C
Oven Temp: 50 °C (hold 3.5 min.) to 180 °C at 35 °C/min. (hold 3.5 min.) to 300 °C at 20 °C/min. (hold 0.5 min.)
Carrier Gas He, constant flow
Flow Rate: 1.2 mL/min.
Detector FID @ 330 °C
Notes FID:
Hydrogen: 30mL/min.
Air: 400mL/min.
Nitrogen: 25mL/min.

10ng 2,4-dinitrophenol (DNP) on-column, single gooseneck liner with wool, FID analysis with phenanthrene internal standard.

Table I  Higher, more consistent responses with Restek's Semivolatiles Wool allow lower detection limits for active compounds.

Restek's Liner with Semivolatiles Wool
Replicate 2,4-DNP Area Phenanthrene Area Response Factor
1 25.1 125.9 0.199
2 26.2 125 0.210
3 29.4 135.9 0.216
4 30.7 140 0.219
    Average RF =   0.211
    STD =   0.009
    %RSD =   4.19
Competitor's MS Certified Liner with Wool
Replicate 2,4-DNP Area Phenanthrene Area Response Factor
1 7.4 162.3 0.046
2 11.8 165 0.072
3 13.5 165 0.082
4 14.8 165.6 0.089
    Average RF =   0.072
    STD =   0.019
    %RSD =   26.51

Figure 2  The inertness of Semivolatiles Wool liners, coupled with the inertness and resolution of Rxi® technology, results in excellent peak shape, resolution, and response for semivolatiles.

1. 1,4-Dioxane
2. N-Nitrosodimethylamine
3. Pyridine
4. 2-Fluorophenol (SS)
5. Phenol-d6 (SS)
6. Phenol
7. Aniline
8. Bis(2-chloroethyl) ether
9. 2-Chlorophenol
10. 1,3-Dichlorobenzene
11. 1,4-dichlorobenzene-d4 (IS)
12. 1,4-Dichlorobenzene
13. Benzyl alcohol
14. 1,2-Dichlorobenzene
15. 2-Methylphenol
16. Bis(2-chloroisopropyl) ether
17. 4-Methylphenol/3-Methylphenol
18. N-Nitrosodi-N-propylamine
19. Hexachloroethane
20. Nitrobenzene-d5 (SS)
21. Nitrobenzene
22. Isophorone
23. 2-Nitrophenol
24. 2,4-Dimethylphenol
25. Benzoic acid
26. Bis(2-chloroethoxy)methane
27. 2,4-Dichlorophenol
28. 1,2,4-Trichlorobenzene
29. Naphthalene-d8 (SS)
30. Naphthalene
31. 4-Chloroaniline
32. Hexachlorobutadiene
33. 4-Chloro-3-methylphenol
34. 2-Methylnaphthalene
35. 1-Methylnaphthalene
36. Hexachlorocyclopentadiene
37. 2,4,6-Trichlorophenol
38. 2,4,5-Trichlorophenol
39. 2-Fluorobiphenyl (SS)
40. 2-Chloronaphthalene
41. 2-Nitroaniline
42. 1,4-Dinitrobenzene
43. Dimethyl phthalate
44. 1,3-Dinitrobenzene
45. 2,6-Dinitrotoluene
46. 1,2-Dinitrobenzene
47. Acenaphthylene
48. 3-Nitroaniline
49. Acenaphthene-d10 (IS)
50. Acenaphthene
51. 2,4-Dinitrophenol
52. 4-Nitrophenol
53. 2,4-Dinitrotoluene
54. Dibenzofuran
55. 2,3,5,6-Tetrachlorophenol
56. 2,3,4,6-Tetrachlorophenol
57. Diethyl phthalate
58. 4-Chlorophenyl phenyl ether
59. Fluorene
60. 4-Nitroaniline
61. 4,6-Dinitro-2-methylphenol
62. N-Nitrosodiphenylamine (Diphenylamine)
63. 1,2-Diphenylhydrazine (as Azobenzene)
64. 2,4,6-Tribromophenol (SS)
65. 4-Bromophenyl phenyl ether
66. Hexachlorobenzene
67. Pentachlorophenol
68. Phenanthrene-d10 (IS)
69. Phenanthrene
70. Anthracene
71. Carbazole
72. di-n-Butyl phthalate
73. Fluoranthene
74. Benzidine
75. Pyrene-d10 (SS)
76. Pyrene
77. p-Terphenyl-d14 (SS)
78. 3,3'-Dimethylbenzidine
79. Butyl benzyl phthalate
80. Bis(2-ethylhexyl) adipate
81. 3,3'-Dichlorobenzidine
82. Benz[a]anthracene
83. Bis(2-ethylhexyl)phthalate
84. Chrysene-d12 (IS)
85. Chrysene
86. Di-n-octyl phthalate
87. Benzo[b]fluoranthene
88. Benzo[k]fluoranthene
89. Benzo[a]pyrene
90. Perylene-d12 (IS)
91. Dibenz[a,h]anthracene
92. Indeno[1,2,3-cd]pyrene
93. Benzo[ghi]perylene
C = Toluene
Semivolatile Organics by EPA Method 8270 on Rxi<sup>®</sup>-5Sil MS (30m, 0.25mm ID, 0.25 µm) w/Single Gooseneck packed with Semivolatiles Wool
Column Rxi®-5Sil MS, 30 m, 0.25 mm ID, 0.25 µm (cat.# 13623)
Sample 8270 MegaMix® (cat.# 31850)
Benzoic acid (cat.# 31879)
8270 Benzidines Mix (cat.# 31852)
Acid Surrogate Mix (4/89 SOW) (cat.# 31025)
Revised B/N Surrogate Mix (cat.# 31887)
1,4-dioxane (cat.# 31853)
SV Internal Standard Mix (cat.# 31206)
Diluent: methylene chloride
Conc.: 10 ng on-column
Inj. Vol.: 1.0 µL pulsed splitless (hold 0.25 min.)
Liner: Gooseneck Splitless (4mm) w/Application-Specific Wool (cat.# 20798-231.1)
Inj. Temp.: 250 °C
Pulse Pressure: 25 psi (172.4kPa)
Pulse Time: 0.3 min.
Purge Flow: 60 mL/min.
Oven Temp: 40 °C (hold 1 min.) to 280 °C at 25 °C/min. to 320 °C at 5 °C/min. (hold 1 min.)
Carrier Gas He, constant flow
Flow Rate: 1.2 mL/min.
Detector MS
Mode: Scan
Transfer Line Temp.: 280 °C
Analyzer Type: Quadrupole
Source Temp.: 250 °C
Tune Type: DFTPP
Ionization Mode: EI
Scan Range: 35-550 amu
Instrument Agilent 7890A GC & 5975C MSD

Figure 3  Improve low level response for active compounds—more than twice the required RF for 2,4-DNP at just 1ng on column. (Extracted ion chromatogram)

1. 2,4-Dinitrophenol
2,4-Dinitrophenol on Rxi<sup>®</sup>-5Sil MS
Column Rxi-5Sil MS, 30 m, 0.25 mm ID, 0.25 µm (cat.# 13623)
Sample 8270 MegaMix® (cat.# 31850)
Conc.: 1 ng on-column
Inj. Vol.: 1.0 µL splitless (hold 0.2 min.)
Liner: Siltek® Gooseneck Splitless (4mm) w/ Semivolatiles Wool (cat.# 22406-231.5)
Inj. Temp.: 250 °C
Oven Temp: 35 °C (hold 1 min.) to 280 °C at 25 °C/min. to 310 °C at 5 °C/min. (hold 1 min.)
Carrier Gas He, constant flow
Flow Rate: 1.2 mL/min.
Detector MS
Mode: Scan
Transfer Line Temp.: 280 °C
Ionization Mode: EI
Scan Range: 35-500 amu

To order the new Semivolatiles Wool in prepacked liners, add the corresponding suffix number to the liner catalog number.

qty. IP Deactivated Liner 
with Semivolatiles Wool
each -231.1 (addl. cost)
5-pk. -231.5 (addl. cost)
25-pk. -231.25 (addl. cost)

By Amanda Rigdon, Pharmaceutical Innovations Chemist and Rick Lake, Pharmaceutical Market Development Manager

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