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Identifying samples

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Besides time, the most basic sample identification is the inlet port number (selector valve position). If the imported ChemStation or CRDS data include the port number, this will be included in the run name. Besides port number, the run name may also include the run type and sample_id:


When the port number is not imported, the sample.log must be used to assign a port number to each run for ChemStation or to each time the selector valve rotates for CRDS. The run type, port number and sampld_id are used from the first place it is found in the order below:

  • sample.log
  • run name
  • ports.log

The ports.log

The ports log is used to identify samples plumbed to each inlet port (air, standard, tank) during each time period. This is useful for automated runs where the sample plumbed to each inlet port is fixed for long periods. This is normally the case for CRDS or GCs operating in the field.

#date    time    port   sample     regulator    type     comment
 090101  0000     3     10m           -         air
 090101  0000     5     50m           -         air
 090101  0000     1     J-101      AP-12345     std
 100615  1230     1     J-102      AP-12345     std

The format of the ports.log is fixed and the header is a comment.

The sample.log

When the port number is not part of the imported data, the sample.log can be used to set the port number for each GC run. For CRDS data, the sample.log only need contain an entry each the selector valve changes position.

date    time    port
130101  1200      1
130101  1210      3

For GC data which are not identified by the ports.log, for example for a lab GC making flask runs, then the sample identification must be included in the sample.log. See Run types and calibration for definition of run types.

date    time    port   type    sample
130101  1200      1    tank    T-123
130101  1210      3    std     S-101

Additional information, such as sample volume, pressure and temperature may also be included:

date    time    port   type    sample  volume  psamp  tsamp  pamb  tamb
130101  1200      1    tank    T-123
130101  1210      3    std     S-101

The format of the sample.log is defined by the header. (Field names which may be used are defined in the config/gcwerks-results.key file.)

File locations

A separate file must be created for each month of sample.log data. The sample.log header may be different in each file, but within each file the columns must be the same.


The ports.log may be contained in a single file (if not too long), or may be organized in monthly or yearly files: