Mass Spectrometer Headspace Sampling via Pressure Reduction

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Solution Overview

Problem

Existing headspace methods for mass spectrometry are limited by the saturation vapor pressure of samples, leading to low sample gas density in the headspace, inefficient ionization, and increased operational complexity due to heating requirements and sample carry-over issues.

Innovation Solution

Decreasing the pressure inside the sample vessel containing the sample allows for increased sample gas density and efficient ionization by connecting it to an ionization housing with a lower pressure, utilizing a vacuum chamber for mass analysis and employing dielectric barrier discharge plasma for soft ionization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the pressure in the headspace part is increased to atmospheric pressure or higher, then the sample can be analyzed at standard conditions, but the density of sample gas in the headspace decreases and ionization efficiency is reduced

Engineering Contradiction:

Improveionization efficiencyVSAvoidsample gas density

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The invention changes the pressure parameter from atmospheric pressure to reduced pressure (vacuum conditions) in the headspace part. This parameter change increases the density of sample gas molecules in the headspace while maintaining efficient ionization, resolving the contradiction between sample gas density and ionization efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a vacuum environment (inert environment without air) in the headspace part by removing air molecules. This eliminates competing air molecules that would reduce sample gas density and ionization efficiency, while allowing direct ionization of sample molecules

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Quantity of substance

If heating is applied to increase saturated vapor pressure of the sample, then the amount of sample gas in the headspace increases, but energy consumption increases and condensation issues occur

Engineering Contradiction:

Improveamount of sample gasVSAvoidenergy consumption

Core Design Contradiction:

Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

Instead of changing temperature (heating) to increase sample gas amount, the invention changes the pressure parameter. By reducing the pressure in the headspace, the sample gas density increases without requiring additional energy input for heating, eliminating the trade-off between sample gas amount and energy consumption

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the thermal method (heating) with a mechanical method (vacuum pumping) to increase sample gas density. This substitution eliminates energy consumption for heating while achieving the same goal of increasing available sample gas for ionization

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If conventional headspace methods are used, then the analysis can be performed at atmospheric pressure, but sample carry-over and operational complexity increase

Engineering Contradiction:

Improveoperational simplicityVSAvoidvacuum system requirements

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The invention merges the headspace sampling function with the vacuum system. The vacuum pump serves dual purposes: maintaining the reduced pressure environment and removing air from the headspace. This integration simplifies operation by eliminating separate heating and air removal steps, while the vacuum infrastructure handles sample carry-over removal

Inventive Principle:

Principle #5Merging (Combining)

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

This approach enhances the sensitivity of mass spectrometry by increasing the sample gas density in the headspace, reducing ion fragmentation, and minimizing sample carry-over, while maintaining a balance between sensitivity and operational costs.

Implementation Method 1

decreasing the pressure inside of the sample vessel that contains the sample

Methodology Applied

Scientific EffectVacuum: Vacuum

Implementation Method 2

the pressure inside of the sample vessel is lower than the pressure inside of the ionization source

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 3

employing dielectric barrier discharge plasma for soft ionization

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 4

ionizing the sample efficiently

Methodology Applied

Scientific EffectIonization: Ionisation

Implementation Method 5

dielectric barrier discharge plasma

Methodology Applied

Scientific EffectDielectric barrier discharge:

Implementation Method 6

a mass spectrometer ionizes substances in a gas phase by an ionization source, introduce ions into a vacuumed part, and subject them to mass analysis

Methodology Applied

Scientific EffectMass spectrometry:

Data Source

PatentEP2562787B1Mass spectrometer and mass analyzing method

Publication Date: 2018.03.28 HITACHI HIGH TECH CORP

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AI summary

A mass spectrometer for efficiently ionizing a sample 7 with less carry-over. The ratio of the amount of sample gas to that of a whole headspace gas is increased by decreasing the pressure inside of a sample vessel in which the sample 7 is sealed thereby efficiently ionizing the sample 7.