Mixed-Mode Chromatographic Packing With pH-Stable Polymer Coating
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Solution Overview
Problem
Conventional silica-based chromatographic columns face limitations such as pH instability, irreversible adsorption of basic solutes, and limited selectivity for highly polar and ionic compounds, particularly in mixed-mode chromatography, leading to poor peak shape and reduced chromatographic performance.
Innovation Solution
A method for synthesizing chromatographic packing material by forming a functionalised silicone-based polymer layer on substrate particles through a series of reactions involving silicone-based polymers, hydrophobic compounds, and amine-containing compounds, creating a stable and selective stationary phase with enhanced selectivity and pH stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silica-based stationary phases are used in conventional chromatography, then good hydrophobic retention and physical strength are achieved, but pH stability deteriorates under acidic and alkaline conditions
Solution Approach 1:
The patent employs a composite stationary phase consisting of a polymeric coating layer applied to a silica support. This composite structure combines the physical strength of silica with the pH stability of polymers, allowing the material to withstand both acidic and alkaline conditions while maintaining structural integrity. The polymeric layer acts as a protective barrier that prevents direct interaction between the silica surface and extreme pH environments.
Solution Approach 2:
The invention modifies the chemical composition parameters of the stationary phase by incorporating specific functional groups (carboxylic acid, sulfonic acid, phenolic hydroxyl) into the polymeric coating. These compositional changes enable the material to maintain stability across a broader pH range (pH 1-13) compared to conventional silica phases, which typically fail outside pH 2-8.
2Manufacturing precision
If end-capping techniques are used to mask acidic silanols, then peak symmetry improves for basic solutes, but selectivity for polar and ionic compounds deteriorates
Solution Approach 1:
The patent introduces different functional groups at specific locations within the polymeric coating structure. The coating contains carboxylic acid groups for ion-exchange interactions with basic solutes, sulfonic acid groups for enhanced polar interactions, and phenolic hydroxyl groups for hydrogen bonding. This spatial and functional differentiation allows the stationary phase to simultaneously achieve good peak symmetry for basics and high selectivity for polar/ionic compounds.
Solution Approach 2:
The polymeric stationary phase is designed with multiple functional groups that provide diverse separation mechanisms within a single phase. The combination of ion-exchange (carboxylic and sulfonic acids), hydrogen bonding (phenolic hydroxyls), and hydrophobic interactions creates a universal stationary phase capable of separating various analyte types including polar, ionic, and basic compounds with high efficiency.
3Area of stationary object
If monofunctional silylating agents are used to form monolayer coatings, then surface coverage is achieved, but chemical stability deteriorates compared to polymeric coatings
Solution Approach 1:
The patent uses a polymeric coating material that forms a thick, cross-linked layer on the silica surface, rather than a thin monolayer. This polymeric composite provides superior chemical stability due to its cross-linked network structure and bulk properties, while still achieving complete surface coverage through the coating process. The polymeric nature allows for better resistance to hydrolysis and chemical degradation compared to monofunctional silylating agent coatings.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting packing material provides improved selectivity and peak shape for charged analytes, maintaining chromatographic integrity across varying pH conditions, addressing the limitations of conventional silica-based columns.
Implementation Method 1
forming silicone-based polymer encapsulated substrate particles comprising pendant functional groups by reacting functional groups on the substrate particles with a silicone-based polymer product comprising pendant functional groups
Implementation Method 2
functionalising the silicone-based polymer encapsulated substrate particles by reacting the pendant functional groups on the silicone-based polymer encapsulated substrate particles with at least one hydrophobic compound
Implementation Method 3
functionalising the first functionalised silicone-based polymer encapsulated substrate particles by reacting the first functionalised silicone-based polymer encapsulated substrate particles with at least one amine containing compound
Implementation Method 4
The selectivity of a stationary phase for analytes is mainly governed by the column chemistry, which is key in LC separation. The column chemistry is routinely controlled by modifying the surface of the stationary phase
Implementation Method 5
The resulting packing material provides improved selectivity and peak shape for charged analytes, maintaining chromatographic integrity across varying pH conditions
Data Source
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AI summary
The present invention relates to the field of chromatographic sample separation that includes liquid chromatography and solid phase extraction and, in particular, it relates to material and the synthesis of material for use as a stationary phase in chromatographic sample separation. The invention further relates to uses of the material, in particular in the separation of hydrophilic and hydrophobic peptides, non-glycosylated and N-linked glycosylated peptides, deamidated and oxidized peptides. The invention also relates to chromatographic columns and solid phase extraction columns containing the material as a stationary phase.