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Method 102 Revision I 5.2.1.3 Rotate the gas sampling valve. This causes the sample to enter the gas chromatographic analyzer. 5.2.2 The procedure for the freeze -out method follows: 5.2.2.1 Immerse the sample trap in liquid nitrogen (LN "� and allow the temperature to stabilize (approximat91y 5 min). 5.2.2.2 After flushing the syringe with about 40 ml, of the sample withdraw exactly 40 mL from the sample bag with the syringe. 5.2.2.3 Transfer the sample into the trap. 5.2.2.4 Backfill the syringe with 40 m.L. of helium and flush the 40 mL through the trap; then flush helium through the trap for 2 minutes at 100 mL/min.. 5.2.2.5 Stop the helium flushing process. 5.2.2.6 Isolate the cryogenic trap by using the isolation valve, which prevent the escape of the sample. 5.2-2.7 Remove the LN containing from the trap and replace it with a Dewar containing hot water at- about 80 degC. 5.2.2.8 Allow the trap to warm up. 5.2.2.9 Actuate the sampling valve, thereby causing the carrier gas stream to flush the sample into the gas chromatograph. 5.3 With the suggested stainless steel column (see item 3.5), typical operating conditions for both loop and freeze - out methods are: Helium flaw: 20 mL/min Heating bath temperature for cryogenic trap: 80 degC Column temperature: ambient Detector temperature: 150 degC 5.4 Concentrations of benzene may be calculated by using a chromatograp'nic da -111"a system or any other suitable elect- ronic integrating device. 6 Calculation 6.1 The benzene concentration in ppb is calculated by the data system using the external standard method: Concentration = Area x Calibration Factor