Method and equipment for measuring global volatile substances

• US 6,397,658 B1
• Filed: 05/15/2000
• Issued: 06/04/2002
• Est. Priority Date: 11/15/1997
• Status: Expired due to Fees

• Current Assignee: Brechbühler AG
• Original Assignee: Brechbühler AG
• Inventors: Villettaz, Jean-Claude, Azodanlou, Ramin, Luisier, Jean-Luc
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): CYGAN, MICHAEL T
• Application Number:
  US09/554,592
• Time in Patent Office: 750 Days
• Field of Search: 73/615.9, 73/617.7, 73/645.6, 73/191.2, 73/233.4, 738/631.2, 738/632.1, 738/632.3, 73/64, 73/44, 422/69, 422/88, 422/89
• US Class Current: 73/19.12
• CPC Class Codes: G01N 1/405 by adsorption or absorption
• CPC Class Codes: G01N 2001/2229 Headspace sampling, i.e. vapour over liquid
• CPC Class Codes: G01N 2030/009 Extraction
• CPC Class Codes: G01N 2030/062 extracting sample from raw material
• CPC Class Codes: G01N 2030/121 cooling; cold traps

Abstract

Measurement of volatile substances in a global manner with no prior separation of the different compounds, wherein the volatiles produced are collected by adsorption on an adsorbent surface, the collected substances are next desorbed directly in a detector, or desorbed and conveyed by means of an inert gas through a capillary tube to a detector, for analysis of the signals obtained.

Claims

1. Method for measuring volatile substances in a global manner, without prior separation of the different compounds, which comprises:

placing a sample to be analyzed in a container with a head space over the sample in the container so that volatile substances are produced in the head space from the sample;

collecting the volatile substances produced in the head space after an equilibration time on a means for collecting the volatile substances which includes adsorption on at least one adsorbent surface introduced into the head space, wherein the means for collecting the volatile substances is based on at least one SPME (Solid Phase Micro Extraction system) and includes an injector with a septum;

removing said adsorbent surface from the head space and transporting the adsorbent surface with collected substances into a desorption system and transferring said collected substances to a detector by one of

desorbing said collected substances directly in said detector, and

desorbing and conveying said collected substances by means of an inert gas through a capillary tube,

wherein said detector detects the volatile substances and produces at least one signal therefrom;

obtaining at least one of a mathematical and statistical analysis of the signal obtained, wherein the analysis is reproducible and correlates with a sensory analysis.

2. Method according to claim 1, wherein the volatile substances comprise the smell of food.

3. Method according to claim 1, wherein the adsorbent surfaces are heated in order to desorb the volatile substances.

4. Method according to claim 1, wherein said signal is transferred from the detector to an evaluation system and the results are expressed in graphical form.

5. Method according to claim 1, wherein the signal is analyzed by measuring at least one of the intensity and shape thereof.

6. Method according to claim 1, wherein the collected substances are conveyed through a capillary tube with substantially no separation thereof.

7. Device for measuring volatile substances in a global manner without prior separation of the different compounds, which comprises:

a container for receiving a sample to be analyzed with a head space therein over the sample in the container for volatile substances produced from the sample;

means for collecting the volatile substances after an equilibration time, including at least one adsorbent surface introduced into the head space, wherein the means for collecting the volatile substances is based on at least one SPME (Solid Phase Micro Extraction system) and includes an injector with a septum;

a desorption system spaced from the container for receiving the adsorbent surface with collected substances;

a detector for receiving the collected volatile substances and producing a signal therefrom; and

an evaluation system for receiving said signal and obtaining at least one of a mathematical and statistical analysis of the signal.

8. Device according to claim 7, wherein said desorption system comprises a thermal desorber desorption unit.

9. Device according to claim 8, wherein said desorption unit is programmable.

10. Device according to claim 7, wherein said detector is at least one of a flame ionization detector, thermal conductivity detector, differential resistivity detector, phosphorous nitrogen detector, electron capture detector, and mass spectrometry detector.