通过坚固、可靠的
Rxi-SVOCms 色谱柱
- 高惰性保持校准通过和样品运行。
- 临界物质对分离效果出色,从而提高分析准确度。
- 柱间性能一致。
- 色谱柱寿命长 。
Restek 新型 Rxi-SVOCms 色谱柱,专为半挥发物分析而设计,可确保性能一致,保持校准通过的时间更长,因此在需要重新校准仪器或更换色谱柱之前可以运行更多样品。色谱柱采用新型聚合物和去活化学品,惰性高,具有严格控制的选择性,对各种分析物(酸性、碱性和中性)的分析性能卓越。
Rxi-SVOCms 色谱柱经过专门调整,可改善挑战性 SVOC(如五氯苯酚、吡啶和联苯胺)的峰形,并可确保难分析的多环芳烃 (PAH) 的分离度更优。如图 1 所示,即使是最麻烦的反应性分析物,也能获得高度对称的峰形和良好的响应。此外,对于苯并[b]荧蒽和苯并[k]荧蒽这些必须进行色谱分离的同重多环芳烃以及茚并[1,2,3-cd]芘和二苯并[a,h]蒽也可获得出色的分离度(≥85% 峰谷)。
对于因色谱柱性能变化、频繁校准失败和色谱柱寿命短而拖慢工作节奏的环保行业化学家,改用坚固耐用的 Rxi-SVOCms 色谱柱可确保在更长时间内满足数据要求,并最大限度减少停工时间。
图 1:Rxi-SVOCms 色谱柱的色谱性能出色,即使分析易出现问题的化合物也能可靠地获得良好的峰形和较好的分离度。如可能,建议采用分流进样,因为这可以最大限度地减少进样口污染对样品转移至分析柱的影响。

Peaks | tR (min) | |
---|---|---|
1. | (IS) 1,4-Dioxane-d8 | 1.87 |
2. | N-Nitrosodimethylamine | 2.00 |
3. | Pyridine | 2.03 |
4. | (SS) 2-Fluorophenol | 2.67 |
5. | (SS) Phenol-d6 | 3.29 |
6. | Phenol | 3.30 |
7. | Aniline | 3.36 |
8. | Bis(2-chloroethyl) ether | 3.40 |
9. | 2-Chlorophenol | 3.46 |
10. | 1,3-Dichlorobenzene | 3.59 |
11. | (IS) 1,4-Dichlorobenzene-D4 | 3.63 |
12. | 1,4-Dichlorobenzene | 3.65 |
13. | Benzyl alcohol | 3.72 |
14. | 1,2-Dichlorobenzene | 3.78 |
15. | 2-Methylphenol | 3.80 |
16. | Bis(2-Chloroisopropyl)ether | 3.84 |
17. | 4-Methylphenol | 3.93 |
18. | 3-Methylphenol | 3.93 |
19. | N-Nitrosodi-N-propylamine | 3.95 |
20. | Hexachloroethane | 4.07 |
21. | (SS) Nitrobenzene-D5 | 4.10 |
22. | Nitrobenzene | 4.11 |
23. | Isophorone | 4.32 |
24. | 2-Nitrophenol | 4.40 |
25. | 2,4-Dimethylphenol | 4.42 |
26. | Benzoic acid | 4.46 |
27. | Bis(2-chloroethoxy)methane | 4.51 |
28. | 2,4-Dichlorophenol | 4.61 |
29. | 1,2,4-Trichlorobenzene | 4.70 |
30. | (IS) Naphthalene-D8 | 4.76 |
31. | Naphthalene | 4.78 |
Peaks | tR (min) | |
---|---|---|
32. | 4-Chloroaniline | 4.82 |
33. | Hexachlorobutadiene | 4.89 |
34. | 4-Chloro-3-methylphenol | 5.26 |
35. | 2-Methylnaphthalene | 5.43 |
36. | 1-Methylnaphthalene | 5.53 |
37. | Hexachlorocyclopentadiene | 5.59 |
38. | 2,4,6-Trichlorophenol | 5.70 |
39. | 2,4,5-Trichlorophenol | 5.73 |
40. | (SS) 2-Fluorobiphenyl | 5.79 |
41. | 2-Chloronaphthalene | 5.91 |
42. | 2-Nitroaniline | 6.00 |
43. | 1,4-Dinitrobenzene | 6.13 |
44. | Dimethyl phthalate | 6.18 |
45. | 1,3-Dinitrobenzene | 6.20 |
46. | 2,6-Dinitrotoluene | 6.24 |
47. | 1,2-Dinitrobenzene | 6.29 |
48. | Acenaphthylene | 6.31 |
49. | 3-Nitroaniline | 6.40 |
50. | (IS) Acenaphthene-D10 | 6.45 |
51. | Acenaphthene | 6.48 |
52. | 2,4-Dinitrophenol | 6.50 |
53. | 4-Nitrophenol | 6.55 |
54. | 2,4-Dinitrotoluene | 6.63 |
55. | Dibenzofuran | 6.65 |
56. | 2,3,5,6-Tetrachlorophenol | 6.73 |
57. | 2,3,4,6-Tetrachlorophenol | 6.77 |
58. | Diethyl phthalate | 6.88 |
59. | 4-Chlorophenyl phenyl ether | 6.99 |
60. | Fluorene | 6.99 |
61. | 4-Nitroaniline | 7.00 |
62. | 4,6-Dinitro-2-methylphenol | 7.03 |
Peaks | tR (min) | |
---|---|---|
63. | N-Nitrosodiphenylamine | 7.10 |
64. | N,N-Diphenylhydrazine | 7.15 |
65. | (SS) 2,4,6-Tribromophenol | 7.23 |
66. | 4-Bromophenyl phenyl ether | 7.47 |
67. | Hexachlorobenzene | 7.53 |
68. | Pentachlorophenol | 7.72 |
69. | (IS) Phenanthrene-D10 | 7.92 |
70. | Phenanthrene | 7.94 |
71. | Anthracene | 7.99 |
72. | Carbazole | 8.15 |
73. | di-n-Butyl phthalate | 8.49 |
74. | Fluoranthene | 9.12 |
75. | Benzidine | 9.24 |
76. | (SS) Pyrene-D10 | 9.32 |
77. | Pyrene | 9.34 |
78. | (SS) p-Terphenyl-d14 | 9.49 |
79. | 3,3'-Dimethylbenzidine | 9.98 |
80. | Butyl benzyl phthalate | 10.00 |
81. | Bis(2-ethylhexyl) adipate | 10.09 |
82. | 3,3'-Dichlorobenzidine | 10.62 |
83. | Benz[a]anthracene | 10.66 |
84. | (IS) Chrysene-D12 | 10.67 |
85. | Chrysene | 10.71 |
86. | Bis(2-ethylhexyl) phthalate | 10.71 |
87. | Di-n-octyl phthalate | 11.68 |
88. | Benzo[b]fluoranthene | 12.30 |
89. | Benzo[k]fluoranthene | 12.34 |
90. | Benzo[a]pyrene | 12.89 |
91. | (IS) Perylene-D12 | 13.00 |
92. | Indeno[1,2,3-cd]pyrene | 15.32 |
93. | Dibenz[a,h]anthracene | 15.40 |
94. | Benzo[ghi]perylene | 15.95 |
Column | Rxi-SVOCms, 30 m, 0.25 mm ID, 0.25 µm (cat.# 16623) |
---|---|
Standard/Sample | |
8270 MegaMix standard (cat.# 31850) | |
8270 Benzidines mix (cat.# 31852) | |
Benzoic acid (cat.# 31879) | |
Revised SV internal standard mix (cat.# 31886) | |
Revised B/N surrogate mix (cat.# 31888) | |
Acid surrogate mix (cat.# 31063) | |
Diluent: | Dichloromethane |
Conc.: | 20 µg/mL |
Injection | |
Inj. Vol.: | 1 µL split (split ratio 10:1) |
Liner: | Topaz 4.0 mm ID single taper inlet liner with wool (cat.# 23303) |
Inj. Temp.: | 250 °C |
Split Vent Flow Rate: | 12 mL/min |
Oven | |
Oven Temp.: | 60 °C (hold 0.5 min) to 285 °C at 25 °C/min to 305 °C at 3 °C/min to 330 °C at 20 °C/min (hold 5 min) |
Carrier Gas | He, constant flow |
Flow Rate: | 1.2 mL/min |
Detector | MS | ||||||||
---|---|---|---|---|---|---|---|---|---|
Mode: | Scan | ||||||||
Scan Program: | |||||||||
| |||||||||
Transfer Line Temp.: | 280 °C | ||||||||
Analyzer Type: | Quadrupole | ||||||||
Source Type: | Inert | ||||||||
Drawout Plate: | 6 mm ID | ||||||||
Source Temp.: | 330 °C | ||||||||
Quad Temp.: | 180 °C | ||||||||
Electron Energy: | 70 eV | ||||||||
Tune Type: | DFTPP | ||||||||
Ionization Mode: | EI | ||||||||
Instrument | Agilent 7890A GC & 5975C MSD | ||||||||
Sample Preparation | Samples were aliquoted into amber 2 mL, 9 mm short-cap, screw-thread vials (cat.# 21143) containing glass Big Mouth inserts (cat.# 21782) and sealed with 2.0 mL, 9 mm short-cap, screw-vial closures (cat.# 23842). |
稳定校准提高样品通量
校准失败意味着生产率损失,因为必须暂停样品分析以进行耗时的维护和重新校准。Rxi-SVOCms 色谱柱惰性增强,可克服这一缺
点。如表 I 所示,考虑所有化合物和色谱柱,可得六个色谱柱初始校准的平均响应因子 %RSD 仅为 6%。响应因子 %RSD 极低且一致,
可确保校准通过持续时间更长,在需要重新校准之前能运行更多样品。如图 2 所示,即使分析不同浓度的吡啶和五氯苯酚也可
观察到一致的峰形和保留时间,这些化合物容易出现问题,在非高惰性色谱柱上往往会拖尾并常难以达到校准标准。
表 I:性能稳定意味着重新校准次数更少,有更多的时间可用于运行样品,从而提高了实验室生产率。绿色表示通过初始校准(n = 6 个色谱柱)。
Compound |
Calibration Range (µg/mL) |
Average %RSD of Response Factors |
N-Nitrosodimethylamine |
1 - 120 |
4.70% |
Pyridine |
1 - 120 |
6.10% |
(SS) 2-Fluorophenol |
1 - 120 |
1.70% |
(SS) Phenol-d6 |
1 - 120 |
2.10% |
Phenol |
1 - 120 |
3.20% |
Aniline |
1 - 120 |
3.10% |
Bis(2-chloroethyl)ether |
1 - 120 |
2.40% |
2-chlorophenol |
1 - 120 |
2.80% |
1,3-dichlorobenzene |
1 - 120 |
2.60% |
1,4-Dichlorobenzene |
1 - 120 |
2.10% |
Benzyl alcohol |
1 - 120 |
3.30% |
1,2-Dichlorobenzene |
1 - 120 |
2.70% |
2-Methylphenol |
1 - 120 |
3.30% |
Bis(2-chloroisopropyl)ether |
1 - 120 |
2.40% |
4-Methylphenol/3-methylphenol |
1 - 120 |
3.30% |
N-nitroso-di-n-propylamine |
1 - 120 |
3.80% |
Hexachloroethane |
1 - 120 |
3.00% |
(SS) Nitrobenzene-D5 |
1 - 120 |
1.60% |
Nitrobenzene |
1 - 120 |
2.60% |
Isophorone |
1 - 120 |
3.40% |
2-Nitrophenol |
1 - 120 |
7.00% |
2,4-Dimethylphenol |
1 - 120 |
3.70% |
Benzoic acid |
2.5 - 120 |
25.00% |
Bis(2-chloroethoxy)methane |
1 - 120 |
3.60% |
2,4-Dichlorophenol |
1 - 120 |
4.10% |
1,2,4-Trichlorobenzene |
1 - 120 |
2.80% |
Naphthalene |
1 - 120 |
3.20% |
4-Chloroaniline |
1 - 120 |
3.90% |
Hexachlorobutadiene |
1 - 120 |
3.70% |
4-Chloro-3-methylphenol |
1 - 120 |
4.40% |
2-Methylnaphthalene |
1 - 120 |
3.40% |
1-Methylnaphthalene |
1 - 120 |
3.60% |
Hexachlorocyclopentadiene |
1 - 120 |
6.90% |
2,4,6-Trichlorophenol |
1 - 120 |
5.90% |
2,4,5-Trichlorophenol |
1 - 120 |
6.20% |
(SS) 2-Fluorobiphenyl |
1 - 120 |
1.10% |
2-Chloronaphthalene |
1 - 120 |
2.80% |
2-Nitroaniline |
1 - 120 |
7.80% |
1,4-Dinitrobenzene |
1 - 120 |
11.10% |
Dimethyl phthalate |
1 - 120 |
3.40% |
1,3-Dinitrobenzene |
1 - 120 |
10.80% |
2,6-Dinitrotoluene |
1 - 120 |
7.80% |
Acenaphthylene |
1 - 120 |
4.10% |
1,2-Dinitrobenzene |
1 - 120 |
8.10% |
3-Nitroaniline |
1 - 120 |
5.80% |
Acenaphthene |
1 - 120 |
3.30% |
2,4-Dinitrophenol |
2.5 - 120 |
17.30% |
4-Nitrophenol |
1 - 120 |
7.90% |
Dibenzofuran |
1 - 120 |
3.50% |
2,4-Dinitrotoluene |
1 - 120 |
11.60% |
2,3,5,6-Tetrachlorophenol |
1 - 120 |
10.40% |
2,3,4,6-Tetrachlorophenol |
1 - 120 |
7.30% |
Diethyl phthalate |
1 - 120 |
4.50% |
4-Chlorophenyl phenyl ether |
1 - 120 |
3.60% |
Fluorene |
1 - 120 |
4.40% |
4-Nitroaniline |
1 - 120 |
9.10% |
4,6-Dinitro-2-methylphenol |
2.5 - 120 |
15.10% |
N-nitrosodiphenylamine |
1 - 120 |
4.60% |
Diphenylhydrazine |
1 - 120 |
4.60% |
(SS) 2,4,6-Tribromophenol |
1 - 120 |
5.50% |
4-Bromophenyl phenyl ether |
1 - 120 |
5.50% |
Hexachlorobenzene |
1 - 120 |
4.30% |
Pentachlorophenol |
1 - 120 |
10.60% |
Phenanthrene |
1 - 120 |
3.70% |
Anthracene |
1 - 120 |
4.80% |
Carbazole |
1 - 120 |
5.30% |
di-n-Butyl phthalate |
1 - 120 |
7.90% |
Fluoranthene |
1 - 120 |
5.10% |
Benzidine |
1 - 120 |
9.30% |
(SS) Pyrene-D10 |
1 - 120 |
1.50% |
Pyrene |
1 - 120 |
4.30% |
(SS) p-Terphenyl-d14 |
1 - 120 |
1.80% |
3,3'-Dimethylbenzidine |
1 - 120 |
9.50% |
Butyl benzyl phthalate |
1 - 120 |
8.60% |
Bis(2-ethylhexyl)adipate |
1 - 120 |
10.50% |
3,3'-Dichlorobenzidine |
1 - 120 |
8.50% |
Benz[a]anthracene |
1 - 120 |
3.20% |
Chrysene |
1 - 120 |
3.70% |
Bis(2-ethylhexyl)phthalate |
1 - 120 |
10.40% |
Di-n-octyl phthalate |
1 - 120 |
13.20% |
Benzo[b]fluoranthene |
1 - 120 |
5.60% |
Benzo[k]fluoranthene |
1 - 120 |
4.90% |
Benzo[a]pyrene |
1 - 120 |
6.30% |
Indeno[123-cd]pyrene |
1 - 120 |
7.20% |
Dibenz[a,h]anthracene |
1 - 120 |
7.50% |
Benzo[ghi]perylene |
1 - 120 |
6.40% |
Average %RSD: |
6.00% |
图 2:高惰性 Rxi-SVOCms 色可给出出色的峰形 和一致的保留时间,即使对于低含量的易分析失败的反应性 化合物也是如此,例如吡啶(碱性胺)和五氯苯酚(酸性苯酚)。
Rxi-SVOCms 色谱柱坚固耐用、寿命长,可轻松恢复性能
高度复杂的环境样品的组分积累是一项常规挑战,但这不一定是色谱柱无法逾越的障碍。柱化学成分的改进确保了即使在非常苛刻的条件下也能保持 Rxi-SVOCms 色谱柱性能持久。在图 3 中,我们给色谱柱重复进样脏样品,监测校准性能,并在每 30 次进样后切断受污染部分。即使在 300 次进样后,也可通过快速切割色谱柱轻松恢复性能,其中只有不到 10% 的化合物未能通过切割后校准检查证明了这一点。通过简单的日常维护即能恢复性能,这意味着可分析更多的样品、减少停机时间和色谱柱更换次数。
图 3:重复暴露于高度复杂的样品后,可通过切割完全恢复色谱柱性能。之后,坚固耐用的 Rxi-SVOCms 色谱柱重新焕发了生机,可继续运行样品而无需更换色谱柱和重新校准。
耐用性测试实验设计(300 个样品)
每天进样 30 次柴油微粒提取物 (NIST SRM 1975),每 10 次进样后运行一次持续校准验证 (CCV)。每日第三次 CCV 后,切割色谱柱,更换衬管、隔垫和进样口分流平板。这一步骤序列重复 10 天,且在第二个色谱柱上重复整个实验。
- 蓝线 涵盖所有 CCV 进样,并展示了由于样品基质污染导致性能先受损(如预期的那样),后经维护完全恢复。
- 绿线仅描绘了维护后 CCV 进样,展示了校准性能的稳定性。
制造时保持各色谱柱性能一致
从专有聚合物化学到最终 QC 测试,Rxi-SVOCms 色谱柱的每个制造流程都经过严格控制和严格测试。因此,色谱柱的柱间性能非常一致,您可通过安装的每根色谱柱获得相同的色谱。Rxi-SVOCms 色谱柱还具有保留时间稳定(即使是 2,4-二硝基苯酚这种经常出现问题的活性化合物也是如此)以及柱流失极低的特点(图 4)。
图 4:每根 Rxi-SVOCms 色谱柱保留时间一致且柱流失低,因此您收到的每根色谱柱都能具有可靠的色谱性能。

Peaks | |
---|---|
1. | 4-Picoline |
2. | 2-Ethylhexanoic acid |
3. | 1,6-Hexanediol |
4. | 4-Chlorophenol |
5. | n-Tridecane |
6. | 1-Methylnaphthalene |
Peaks | |
---|---|
7. | 1-Undecanol |
8. | n-Tetradecane |
9. | Dicyclohexylamine |
10. | Acenaphthene-d10 |
11. | 2,4-Dinitrophenol |
12. | Pentachlorophenol |
13. | Benzidine |
Column | Rxi-SVOCms, 30 m, 0.25 mm ID, 0.25 µm (cat.# 16623) |
---|---|
Standard/Sample | Low-level activity test mix |
Diluent: | Dichloromethane |
Conc.: | 200 µg/mL |
Injection | |
Inj. Vol.: | 1 µL split (split ratio 200:1) |
Liner: | Topaz 4.0 mm ID Precision inlet liner with wool (cat.# 23305) |
Inj. Temp.: | 250 °C |
Split Vent Flow Rate: | 236 mL/min |
Oven | |
Oven Temp.: | 125 °C (hold 12.5 min) to 340 °C at 20 °C/min (hold 4 min) |
Carrier Gas | He, constant flow |
Linear Velocity: | 32 cm/sec @ 125 °C |
Dead Time: | 1.5885 min @ 125 °C |
Detector | FID @ 350 °C |
---|---|
Make-up Gas Flow Rate: | 40 mL/min |
Make-up Gas Type: | N2 |
Hydrogen flow: | 40 mL/min |
Air flow: | 400 mL/min |
Data Rate: | 50 Hz |
Instrument | Agilent 7890B GC |
Sample Preparation | Samples were aliquoted into amber 2 mL, 9 mm short-cap, screw-thread vials (cat.# 21143) containing glass Big Mouth inserts (cat.# 21782) and sealed with 2.0 mL, 9 mm short-cap, screw-vial closures (cat.# 23842). |
可靠分离具有挑战性的环境 PAH 化合物
多环芳烃 (PAH) 是使用半挥发物方法过程中最难分离的一些化合物。要实现准确报告痕量结果,色谱柱需要具有高度选择性且柱效高,这样才能够可靠分离紧密洗脱的化合物。如图 5 所示,Rxi-SVOCms 色谱柱优化分离了 23 种优先污染物,(包括苯并[b]荧蒽和苯并[k]荧蒽),它们须进行色谱分离才能实现单独报告。
图 5:Rxi-SVOCms 色谱柱可优化分离紧密洗脱的优先 PAH 污染物,包括仅通过 MS 无法区分的临界同重素。

Peaks | tR (min) | |
---|---|---|
1. | Naphthalene | 6.27 |
2. | 2-Methylnaphthalene | 7.09 |
3. | 1-Methylnaphthalene | 7.20 |
4. | Biphenyl | 7.65 |
5. | 2,6-Dimethylnaphthalene | 7.84 |
6. | Acenaphthylene | 8.17 |
7. | Acenaphthene | 8.38 |
8. | 2,3,5-Trimethylnaphthalene | 8.85 |
9. | Fluorene | 9.01 |
10. | Dibenzothiophene | 10.02 |
11. | Phenanthrene | 10.18 |
Peaks | tR (min) | |
---|---|---|
12. | Anthracene | 10.24 |
13. | 1-Methylphenanthrene | 10.94 |
14. | Fluoranthene | 11.64 |
15. | Pyrene | 11.91 |
16. | Benz[a]anthracene | 13.45 |
17. | Chrysene | 13.50 |
18. | Benzo[b]fluoranthene | 15.13 |
19. | Benzo[k]fluoranthene | 15.18 |
20. | Benzo[a]pyrene | 15.69 |
21. | Indeno[1,2,3-cd]pyrene | 17.77 |
22. | Dibenz[a,h]anthracene | 17.82 |
23. | Benzo[ghi]perylene | 18.26 |
Column | Rxi-SVOCms, 30 m, 0.25 mm ID, 0.25 µm (cat.# 16623) |
---|---|
Standard/Sample | Custom PAH SIM standard |
Diluent: | Dichloromethane |
Conc.: | 40 µg/mL |
Injection | |
Inj. Vol.: | 1 µL split (split ratio 20:1) |
Liner: | Topaz 4.0 mm ID single taper inlet liner with wool (cat.# 23303) |
Inj. Temp.: | 250 °C |
Split Vent Flow Rate: | 24 mL/min |
Oven | |
Oven Temp.: | 40 °C (hold 0.5 min) to 280 °C at 20 °C/min to 330 °C at 6 °C/min (hold 4 min) |
Carrier Gas | He, constant flow |
Flow Rate: | 1.2 mL/min |
Detector | MS | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Mode: | SIM | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
SIM Program: | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Transfer Line Temp.: | 280 °C | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Analyzer Type: | Quadrupole | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Source Type: | Extractor | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Extractor Lens: | 6 mm ID | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Source Temp.: | 330 °C | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Quad Temp.: | 150 °C | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Tune Type: | DFTPP | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Ionization Mode: | EI | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Instrument | Agilent 7890B GC & 5977A MSD | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Sample Preparation | 200 ppm standard diluted 5x, then analyzed at 20:1 split. Samples were aliquoted into amber 2 mL, 9 mm short-cap, screw-thread vials (cat.# 21143) containing glass Big Mouth inserts (cat.# 21782) and sealed with 2.0 mL, 9 mm short-cap, screw-vial closures (cat.# 23842). |