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Novel nanocomposites and their application as monolith columns

a nanocomposites and monolithic technology, applied in the field of new nanocomposites and their application as monolith columns, can solve the problems of insufficient separation performance, many organic chromatographic materials shrink and swell, and most organic chromatographic materials do not have the mechanical strength of typical chromatographic silicas, etc., to achieve novel physical characteristics, enhance capillary wall adhesion, and increase shrinkage resistance

Inactive Publication Date: 2007-06-21
WATERS TECH CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012] The present invention provides novel hybrid inorganic / organic materials and methods for their preparation. In particular, the invention provides nanocomposite monolith materials having increased resistance to shrinkage and novel physical characteristics. The nanocomposites of the invention have enhanced capillary wall adhesion as compared to prior art monolith materials. The improved adhesion of the monoliths of the invention enables the preparation of capillary columns with an internal diameter (I.D.) ≧150 μm.

Problems solved by technology

However, organic chromatographic materials generally result in columns with low efficiency, leading to inadequate separation performance, particularly with low molecular-weight analytes.
Furthermore, many organic chromatographic materials shrink and swell when the composition of the mobile phase is changed.
In addition, most organic chromatographic materials do not have the mechanical strength of typical chromatographic silicas.
However, a further problem associated with silica particles and polymer particles is packed bed stability.
As a result, such tightly packed columns afford high column backpressures that are not desirable.
Moreover, bed stability problems for these chromatography columns are still typically observed because of particle rearrangements.
The presence of large macropores allows liquid to flow directly through with very little resistance resulting in very low backpressures even at high flow rates.
However, due to the shrinkage of the silica skeleton, silica capillaries with an I.D. larger than 50 μm showed much lower efficiency, and in all cases 5-15% of the length of each capillary end had to be cut off to remove large voids caused by shrinkage that formed between the monolith and capillary wall before the capillary could be used.
However, these hybrid-type silica monoliths capillaries still had large voids caused by shrinkage that formed between the monolith and capillary wall and required cutting of 5-15% of the length of each capillary end before use.
Although Zare's work has been successfully applied in electrochromatography, poor column efficiency, poor adhesion between the capillary wall and the monolith structure, and inhomogeneity of the monolith structure were observed in pressure driven separations.(6) Moreover, as a consequence of the utilization of photopolymerization rather than thermal polymerization, the polyimide coating of the glass capillary must be removed prior to use.
This unprotected fused silica tubing becomes very fragile and is easily broken.
Current monolith columns have significant shrinkage, resulting in poor wall adhesion, and consequently, only columns with an I.D. of less than 150 μm have been prepared.

Method used

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  • Novel nanocomposites and their application as monolith columns
  • Novel nanocomposites and their application as monolith columns
  • Novel nanocomposites and their application as monolith columns

Examples

Experimental program
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Effect test

example 1

[0164] A Harvard Apparatus Model ‘33’ Dual Syringe Pump(Harvard Apparatus Inc., Hollistion, Mass., or equivalent) and 10 mL Pharmaseal® syringe (American Pharmaseals Laboratory, Glendale, Calif., or equivalent) were used in all capillary filling and purging steps.

[0165] A fused silica capillary column (ca. 2 m in length) was treated by the following five steps: (1) the column was purged with 1N NaOH at a flow rate of 50 μL / min for at least 5 minutes, sealed via compression fittings and heated to 90° C. for 17 hours; (2) the column was purged with 1N HCl water solution at a flow rate of 50 μL / min for at least 5 minutes; (3) the column was rinsed with water, acetone, and then toluene at a flow rate of 50 μL / min for 10 minutes each (total volume ˜500 μL, >10 times column volume); (4) the column was filled with a mixture of 0.5 mL (3-methacryloxypropyl)trimethoxysilane / 0.5 mL pyridine / 10 mL toluene at a flow rate of 50 μL / min for 5 minutes, sealed at both ends of the column and the col...

example 2

[0167] Pluronic® F38 (Example 2a—0.622 g, Example 2b—0.596 g) and urea (Example 2a—0.517 g, Example 2b—0.515 g) were added to 5 mL of a 15 mM acetic acid solution at room temperature in a glass vial. The solutions were deoxygenated by nitrogen gas purging for at least 2 minutes before Vazo® 64 (1-2 mg) was added, and then the solution was cooled to 0° C. In a separate glass vial, a 2 mL silane mixture (4 / 1 TMOS:MAPTMOS v / v) was prepared and then cooled to 0° C. Next, the silane mixture was added slowly to the acetic acid solution. The combined solutions were stirred at 0° C. for 1 h and then at room temperature (rt) for 1.75 h.

[0168] The resulting solutions were delivered into two separate 50 μm (I.D.)×40 mm (L) capillary columns that were surface treated as described in Example 1 with the exception that step (1) was run for 2 hours. The columns were then sealed at both ends with two compression screws and were heated at 45° C. in an oven for 18.5 h.

[0169] Monolith morphology of t...

example 3

[0170] As described in Example 2, Pluronic® F38 and urea were added to 5 mL of an acetic acid solution at room temperature. The solutions were deoxygenated by nitrogen gas purging for at least 2 minutes before Vazo® 64 was added. The stirred solutions were cooled to 0° C. for a specific time, and 2 mL of a 0° C. silane mixture (4 / 1 TMOS:MAPTOS v / v) was added slowly to the acetic acid solution. The combined solutions were stirred at 0° C. for a prescribed time and then at rt for an additional time period.

[0171] The resulting solutions were delivered into separate 150 μm (I.D.)×40 mm (L) capillary columns that had been surface treated as described in Example 1. The columns were then sealed at both ends with two compression screws and were heated at 65° C. for a prescribed time and then at an elevated temperature (Example 3a,b 120° C.; Example 3c-j 105° C.; Example 3k-o 110° C.; Example 3p-t 125° C.) for an additional time period.

[0172] Monolith morphology of the cross-sections of ea...

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Abstract

Novel materials for chromatographic separations, processes for their preparation, and separation devices containing the chromatographic materials. In particular, hybrid inorganic / organic monolith materials comprising a polymerized scaffolding nanocomposite (PSN), wherein the nanocomposite contains a scaffolding functionality capable of chemically interacting with a surface of a second material are described. The hybrid inorganic / organic materials have enhanced wall adhesion and increased resistance to shrinkage as compared to prior art monolith materials. The improved adhesion of the monoliths enable the preparation of capillary columns with an internal diameter (I.D.) ≧50 μm.

Description

RELATED APPLICATION [0001] This application claims the benefit of U.S. provisional patent application Ser. No. 60 / 474,068 filed May 28, 2003, the disclosure of which application is incorporated herein in its entirety by this reference.BACKGROUND OF THE INVENTION [0002] Packing materials for liquid chromatography (LC) are generally classified into two types: organic materials, e.g., polydivinylbenzene; and inorganic materials typified by silica Many organic materials are chemically stable against strongly alkaline and strongly acidic mobile phases, allowing flexibility in the choice of mobile phase pH. However, organic chromatographic materials generally result in columns with low efficiency, leading to inadequate separation performance, particularly with low molecular-weight analytes. Furthermore, many organic chromatographic materials shrink and swell when the composition of the mobile phase is changed. In addition, most organic chromatographic materials do not have the mechanical ...

Claims

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Application Information

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IPC IPC(8): B32B1/02C08L83/00
CPCB01J20/285B01J2220/82B01J2220/86B82Y30/00C08G77/20Y10T428/26B01D15/206B01D15/22B01J20/26B05D7/22C08J5/005B01D15/265Y10T428/31612Y10T428/31663
Inventor O'GARA, JOHN E.DING, JULIAWALSH, DANIEL
Owner WATERS TECH CORP
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