Capillary Makeup Gas Flow Rate - HP 5890 Series II Plus Reference Manual

Detector Systems
This chapter provides information for the five HP 5890 SERIES II
(hereafter referred to as HP 5890) detector systems:
Flame Ionization Detector (FID)
Nitrogen•PhosphorusDetector (NPD)
Electron Capture Detector (ECD)
Thermal Conductivity Detector (TCD)
Flame Photometric Detector (FPD)

Capillary makeup gas flow rate

Detectors are designed to operate best with a carrier flow rate of at least
20 ml/min, typical of packed column applications. Carrier flow rates less
than about 10 ml/min (typically capillary applications) require capillary
makeup gas to ensure a total flow rate (carrier + makeup) of at least
20 ml/min. The TCD is an exception, requiring a total flow rate of only
5 ml/min.
For the FID, NPD, and TCD, HP Series 530
used without capillary makeup gas, as long as carrier flow rate is between
10 and 20 ml/min. Some loss of detector sensitivity may occur at lower
flow rates.
For the ECD, capillary makeup gas should be used even with HP Series
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530
flow rate (at least 25 ml/min).
Makeup gas is added directly to H for an FID or NPD within the
detector flow manifold; for an ECD or TCD, it is added into the column
effluent stream via a capillary makeup gas adapter fitted into the
detector column inlet.
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capillary columns, because the large cell size requires high total
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capillary columns may be