BS EN ISO 3924:2016 pdf download.Petroleum products —Determination of boilingrange distribution —Gas chromatography method.
6.5Flow / pressure controllers.
6.5.1 lf a packed column is used, the chromatograph shall be equipped with constant-flow controllerscapable of maintaining the carrier gas flow constant to ±1 % over the full operating temperature range.6.5.2 lf a wide-bore capillary column is used, the chromatograph shall be equipped with a controllerof carrier gas flow or pressure appropriate for the inlet used.
6.6 Micro-syringe, this apparatus is used to introduce the sample into the chromatograph. Sampleinjection may be either manual or automatic. Automatic sample injection is preferred because it givesbetter retention time precision.
7 Sampling
Unless otherwise specified, samples shall be taken by the procedures described in lSo 3170 orIS0 3171.
Preparation of apparatus
8.1 Column preparation,any satisfactory method that will produce a column meeting therequirements of 6.2 may be used.The column shall be conditioned at the maximum operatingtemperature to reduce baseline shifts due to bleeding of the column substrate.
8.1.1 Packed columns, an acceptable method of column conditioning. which has been found effectivefor columns with an initial loading of 10 % liquid phase, consists of purging the column with carrier gas atthe normal flow rate while holding the column at the maximum operating temperature for 12 h to 16 h.
8.1.2 Capillary columns, capillary columns may be conditioned using the following procedure.
a) Install the column following the manufacturer's instructions. Set the column and detector gas
flows.Ensure that the system is leak free.
b) Allow the system to purge with carrier gas at ambient temperature for at least 30 min. Then
increase the oven temperature by approximately 5 C/min to 10 °C/min to the final operatingtemperature and hold for approximately 30 min.
c)Cycle the chromatograph through its temperature programme several times until a stable baseline
is obtained.
NOTE1 Capillary columns with cross-linked and bonded phases are available from many manufacturers andare usually preconditioned.These columns have much lower column bleed than packed columns.
NOTE2 The column is not always connected to the FID when making a first conditioning of the column toovercome that initial column bleed affects the detector's sensitivity.
