System and method of matrix accelerated vacuum-assisted sorbent extraction for improved sample preparation prior to GCMS analysis
Techniques disclosed herein can improve the extraction of chemicals prior to analysis by GC or GCMS. A liquid or solid sample can be placed in a sample container of a closed system under vacuum that further includes a sample extraction device. The assembly can be placed in a 3-zone heater that can separately control the temperature of the bottom of the sample container, the top of the sample container, and the sample extraction device. Vapor flux from the bottom of the sample container into the headspace of the sample container can deliver compounds of interest to the sample extraction device, whereas matrix compounds can re-condense in the headspace of the sample container to avoid delivery to the sample extraction device. Extraction can continue until substantial transfer of compounds of interest to the sorbent occurs, followed by thermal desorption of the extract into a GCMS for analysis.
1 . A closed system for preparing a sample under vacuum, the system comprising:
a sample container configured to hold the sample, wherein a bottom of the sample container is positioned within a zone A and a headspace of the sample container is positioned within a zone B;
a sorbent positioned within a zone C, wherein the zone C is positioned in an area of the closed system that does not overlap zone A and/or zone B, wherein the sorbent is configured to extract the sample from a vapor of a matrix of the sample;
a first heater disposed in zone A;
a computer temperature control system configured to induce boiling of the matrix of the sample by controlling the first heater and applying a first temperature to a first portion of the sample container at the zone A,
wherein the computer temperature control system comprises at least one or more heat sinks, fans, or electronic cooling systems configured to maintain a second temperature within a zone B between the zone A and a zone C, the zone B including a second portion of the sample container, via a combination of the computer temperature control system and condensation of the matrix of the sample in the zone B, wherein the second temperature is less than the first temperature;
a second heater disposed in zone C; and
wherein the computer temperature control system is additionally configured to prevent the condensation and sustain the vapor of the matrix of the sample by controlling the second heater and applying a third temperature at the zone C, that is greater than the second temperature, to the sorbent; and
a vacuum-tight seal formed between the sample container, a vacuum sleeve, and a sample extraction device, creating a closed system in which mass cannot enter or exit the closed system once initial headspace compounds have been evacuated.
2 . The system of claim 1 , wherein the sorbent is disposed in a sample extraction device, the sample extraction device configured to be removed from the system for analysis of one or more compounds of the sample.
3 . The system of claim 1 , wherein the computer temperature control system is further configured to control the first heater to periodically modify the first temperature.
4 . The system of claim 1 , wherein the system does not include transfer lines between the sample container and the sorbent.
5 . The system of claim 1 , wherein the system does not include a physical stirring apparatus.
6 . The system of claim 1 , wherein the sorbent is configured to collect one or more compounds of the sample and repel a matrix of the sample.
7 . The system of claim 1 , wherein the sample extraction device contains the sorbent.
8 . The system of claim 7 , wherein the sample extraction device includes a port or a seal configured to be coupled to a vacuum source while a vacuum is being pulled in the system.
9 . A method of preparing a sample in a closed system under vacuum, the method comprising:
at the closed system, the system comprising a sample container, a sorbent positioned within a zone C, wherein the sorbent is configured to extract the sample from a vapor of a matrix of the sample, a computer temperature control system, while the sample is disposed in the sample container and a bottom of the sample container is positioned within a zone A and a headspace of the sample container is positioned within a zone B, a first heater positioned in the zone A, and a second heater positioned in the zone C:
controlling the first heater, with the computer temperature control system, a first temperature to a first portion of the sample container to include boiling of the matrix of the sample at the zone A;
maintaining, with the computer temperature control system, a second temperature within a zone B between the zone A and the zone C, the zone B including a second portion of the sample container, via a combination of the computer temperature control system and condensation of the matrix of the sample in the zone B, wherein the computer temperature control system comprises one or more heat sinks, fans, or electronic cooling systems, wherein the second temperature is less than the first temperature; and
controlling the second heater, with the computer temperature control system, a third temperature that is greater than the second temperature to the sorbent at the zone C such that the vapor of the matrix of the sample is sustained in zone C, the zone C being above the zone A and the zone B and does not overlap zone A and/or zone B; and
forming a vacuum-tight seal between the sample container, a vacuum sleeve, and a sample extraction device, creating a closed system in which mass cannot enter or exit the closed system once initial headspace compounds have been evacuated.
10 . The method of claim 9 , further comprising:
drawing, via a vacuum pump, a vacuum in the system; and
after drawing the vacuum, maintaining the vacuum in the system, wherein the first, second, and third temperatures are applied while the vacuum is maintained in the system.
11 . The method of claim 10 , wherein the vacuum is drawn through a port or a seal of the sample extraction device including the sorbent.
12 . The method of claim 9 , further comprising:
periodically modifying the first temperature with the computer temperature control system.
13 . The method of claim 9 , further comprising:
collecting, via the sorbent, one or more compounds of the sample; and
repelling, via the sorbent, a matrix of the sample.
14 . The method of claim 13 , further comprising:
after collecting the one or more compounds of the sample:
removing a sample extraction device that includes the sorbent from the system; and
analyzing the one or more compounds of the sample.