ASTM E594 for Testing FIDs Used in Gas or Supercritical Fluid Chromatography
1. Scope
1.1 This practice serves as a guide for the testing of the performance of a flame ionization detector (FID) used as the detection component of a gas or supercritical fluid (SF) chromatographic system.
1.2 This recommended practice is directly applicable to an FID that employs a hydrogen-air or hydrogen-oxygen flame burner and a d-c biased electrode system.
1.3 This recommended practice covers the performance of the detector itself, independently of the chromatographic column, the column-to-detector interface (if any), and other system components, in terms that the analyst can use to predict overall system performance when the detector is made part of a complete chromatographic system.
1.4 For general gas chromatographic procedures, Practice E 260 should be followed except where specific changes are recommended herein for the use of an FID. For definitions of gas chromatography and its various terms see Recommended Practice E 355.
1.5 For general information concerning the principles, construction, and operation of an FID, see Refs (1, 2, 3, 4).
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific safety information, see Section 5.
2. Referenced Documents
2.1 ASTM Standards:
E 260 Practice for Packed Column Gas Chromatography
E 355 Practice for Gas Chromatography Terms and Relationships
E 1449 Standard Guide for Supercritical Fluid Chromatography Terms and Relationships
2.2 CGA Standards:
CGA P-1 Safe Handling of Compressed Gases in Containers
CGA G-5.4 Standard for Hydrogen Piping Systems at Consumer Locations
CGA P-9 The Inert Gases: Argon, Nitrogen and Helium
CGA V-7 Standard Method of Determining Cylinder Valve Outlet Connections for Industrial Gas Mixtures
CGA P-12 Safe Handling of Cryogenic Liquids
HB-3 Handbook of Compressed Gases
3. Terminology
3.1 Definitions:
3.1.1 drift - the average slope of the baseline envelope expressed in amperes per hour as measured over 1/2 h.
3.1.2 noise (short-term) - the amplitude expressed in amperes of the baseline envelope that includes all random variations of the detector signal of a frequency on the order of 1 or more cycles per minute (see Fig. 1).
3.1.2.1 Discussion - Short-term noise corresponds to the observed noise only. The actual noise of the system may be larger or smaller than the observed value, depending upon the method of data collection or signal monitoring from the detector, since observed noise is a function of the frequency, speed of response, and the bandwidth of the electronic circuit measuring the detector signal.
3.1.3 other noise - Fluctuations of the baseline envelope of a frequency less than 1 cycle per minute can occur in chromatographic systems.
3.1.4 Discussion - The amplitude of these fluctuations may actually exceed the short-term noise. Such fluctuations are difficult to characterize and are not typically to be expected. They are usually caused by other chromatographic components such as the column, system contaminants, and flow variations. These other noise contributions are not derived from the detector itself and are difficult to quantitate in a general manner. It is, however, important for the practicing chromatographer to be aware of the occurrence of this type of noise contribution.
