Post-Column Additive Mixing in LC-MS for Compound-Specific Ionization
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Solution Overview
Problem
Conventional liquid chromatograph mass spectrometry (LC-MS) methods face challenges in achieving high ionization efficiency for various compounds, leading to suboptimal detection sensitivity, particularly when dealing with samples containing compounds with different characteristics.
Innovation Solution
A method and device for LC-MS that uses two additive supply sections to mix reagents with specific properties into the eluate post-column, adjusting flow rates based on compound characteristics to enhance ionization efficiency in the atmospheric pressure ion source, utilizing reagents that affect charge state and droplet formation/vaporization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single reagent is added to the mobile phase or eluate, then the ionization efficiency for certain compounds may be improved, but the ionization efficiency for various compounds with different characteristics cannot be optimized simultaneously
Solution Approach 1:
The invention divides the reagent addition system into multiple independent channels (first reagent addition section and second reagent addition section), each capable of adding different reagents to the eluate. This segmentation allows different reagents to be optimally selected for different compounds, thereby improving ionization efficiency for various compounds simultaneously while enhancing detection sensitivity
Solution Approach 2:
The atmospheric pressure ion source is designed to handle multiple reagent types and configurations, serving universal functions for diverse compound analysis. The system can adaptively select and combine different reagents based on sample characteristics, making the ionization system versatile for analyzing various compounds with different characteristics
2Measurement precision
If the amount of reagent addition is increased, then ionization efficiency may improve, but the amount of eluate introduced into the atmospheric pressure ion source increases which may reduce effectiveness
Solution Approach 1:
The invention adds reagents at specific locations (post-column addition to eluate) rather than uniformly throughout the system. By introducing reagents locally at the eluate outlet before the atmospheric pressure ion source, the system achieves effective ionization enhancement without unnecessarily increasing the total volume of eluate processed
Solution Approach 2:
The system enables precise control of reagent addition parameters (type, amount, timing) to optimize ionization efficiency. By adjusting reagent concentration and flow rates independently in different addition sections, the system achieves high ionization efficiency without excessive eluate volume introduction
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
Improves ionization efficiency and detection sensitivity by combining reagents like DMSO and 2-propanol, allowing for higher ionization efficiency and detection of compounds that were previously undetectable, especially for high-molecular biological compounds.
Implementation Method 1
a so-called 'atmospheric pressure ionization (API) method', such as an electrospray ionization (ESI) method, atmospheric pressure chemical ionization (APCI) method or atmospheric pressure photoionization (APPI) method, is employed to ionize compounds in an eluate
Implementation Method 2
a reagent which affects the charge state of the eluate is used as the first additive
Implementation Method 3
In order to improve the ionization efficiency, it is important to promote atomization and vaporization of the sprayed droplets
Implementation Method 4
the eluate is sprayed through a spray nozzle into an ambience of substantially atmospheric pressure, and the compounds in the fine droplets produced by the spraying process are ionized
Data Source
Figure 1
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AI summary
In an LC/MS analysis of a sample containing various compounds, additive supply pumps 164A and 164B in a post-column adding unit 16 draw and supply different kinds of additives A and B from containers 163A and 163B, respectively. The additives are mixed into an eluate through T-joints 162 and 161. A preferable combination of the additives is the combination of DMSO which produces the effect of gathering charge states and 2-propanol which produces the effect of promoting atomization or vaporization of droplets. By mixing the two additives into the eluate while mixing them at an appropriate flow-rate ratio according to a previously determined flow-rate program, the ionization efficiency can be nearly optimized for each compound during the process of generating ions by spraying electrically charged droplets of the eluate from an ESI spray 21. Consequently, the detection sensitivity becomes higher than conventional levels.