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US5374755A Expired / Lapsed US ⏱️ 0.0 years remaining

Liquid chromatography stationary phases with reduced silanol interactions

Assignee: Waters Technologies Corp
•
Filing: 1992-07-17
•
Granted: 1994-12-20
•
Expires: 2012-07-17
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Abstract

Abstract Novel carbamate compounds, novel silylcarbamate compounds and novel reversed phase materials comprising a silica substrate modified with a modified novel silylcarbamate compound are disclosed which may, for example, be used as stationary phases for liquid chromatography applications. Attached to the carbamate group are several reversed or normal phase producing groups such as cyanoalkyl, tertiary butyl, dibutyl, octyl, dodecyl, tetradecyl, octadecyl or benzyl. The new stationary phases may be endcapped with a short chain alkyl silane. One particular advantage of these stationary phases is decreased interaction with basic samples due to shielding of the unreacted silanol groups on the silica surface. The new phases are particularly useful in the chromatographic analysis of basic samples or more generally for samples having an undesirable interaction with the unmodified silanols.

Inventors

  • 👤 Uwe D. Neue
  • 👤 Carsten L. Niederlaender
  • 👤 John S. Petersen

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-01 21:04
CPC Classifications
B; B01; B01J; B01J20/00; B01J20/30; B01J20/32; B01J20/3214; B01J20/3225; B01J20/3227; B01D; B01D15/00; B01D15/08; B01D15/26; B01D15/32; B01D15/325; B01J20/281; B01J20/286; B01J20/3202; B01J20/3204; B01J20/3231; B01J20/3242; B01J20/3244; B01J20/3246; B01J20/3257; B01J20/3259; B01J20/3261; C; C07; C07C; C07C271/00; C07C271/06; C07C271/08; C07C271/10; C07C271/12; C07C271/22; C07F; C07F7/00; C07F7/02; C07F7/08; C07F7/12; C07F7/18; C07F7/1804

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 73 words
A surface modified silica of the formula III, ##STR11## wherein l, m, o, r, s, t and u are 0 or 1, n is 0,1, 2 or 3 p is 0,1,2,3 or 4 and q is an integer from 0 to 19; R 3 is selected from the group consisting of hydrogen, alkyl, cyano and phenyl; and R 4 and R 6 are selected from the group consisting of oxygen, methyl and ethyl.
Claim 2
Dependent Claim 73 words
A surface modified silica of the formula III, ##STR11## wherein l, m, o, r, s, t and u are 0 or 1, n is 0,1, 2 or 3 p is 0,1,2,3 or 4 and q is an integer from 0 to 19; R 3 is selected from the group consisting of hydrogen, alkyl, cyano and phenyl; and R 4 and R 6 are selected from the group consisting of oxygen, methyl and ethyl.
Claim 3
Dependent Claim 72 words
A silica having a surface to which is bonded 1 to 7 μeq/M 2 of Si(R 7 ) v (CH 2 ) 3 O(CO)N(CH 2 ) p H(CH 2 ) q R 3 , wherein R7 is methyl or ethyl, v is 0,1 or 2, p is 0,1,2,3 or 4, q is an integer of 0 and 19 and R 3 is selected from the group consisting of cyano, phenyl and hydrogen.
Claim 4
Dependent Claim 72 words
A silica having a surface to which is bonded 1 to 7 μeq/M 2 of Si(R 7 ) v (CH 2 ) 3 O(CO)N(CH 2 ) p H(CH 2 ) q R 3 , wherein R7 is methyl or ethyl, v is 0,1 or 2, p is 0,1,2,3 or 4, q is an integer of 0 and 19 and R 3 is selected from the group consisting of cyano, phenyl and hydrogen.
Claim 5
Dependent Claim 23 words
The silica of any or of claims 1 or 2, when said modified silica surface is endcapped with a short alkyl chain silane.
Claim 6
Dependent Claim 49 words
The process of effecting chromatographic separations of a sample in a column which comprises: packing said column with a modified silica of any one of claims 1 or 2, injecting a sample in said column and separating compounds in said sample by flow of a solvent through said column.
Claim 7
Dependent Claim 17 words
The process of claim 4 wherein said modified silica is endcapped with a short alkyl chain silane.

References Cited (Backward Citations)

US4474704A Cited
US4448694A Cited
US4812512A Cited
US4824950A Cited
US4894468A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1997-12-19 1998-06-20 1998-12-20 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 2001-12-19 2002-06-20 2002-12-20 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2005-12-19 2006-06-20 2006-12-20 $7700.00 Window Closed / Lapsed

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