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Section No 8 <br /> Revision No 0 <br /> Date September 5, 1991 <br /> Page 4 of 5 <br /> Calibration should be checked for each series of measurements in the <br /> field and adjusted accordingly During instrument operation, it is important <br /> to note that salinity levels affect the measurement of dissolved oxygen <br /> Correspondingly, the salinity of the water being evacuated should be known or <br /> estimated, and readings adjusted appropriately as described in the operating <br /> manual In addition, accurate measurements of dissolved oxygen require that <br /> the probe or solution being monitored be kept in constant motion <br /> 8 1 5 Gas Chromatograph <br /> 8 1 5 1 Operation Principles - The calibration procedures presented for <br /> ® gas chromatography will be used with the Hewlett-Packard (HP) 5890A/19394 gas <br /> chromatographic system or the Photovac field gas chromatographic system The <br /> operating principles for both systems are similar A sample is injected into <br /> a packed or capillary column and is carried through the column by an inert <br /> gas The column serves to separate the individual constituents infected into <br /> the column Exiting the column, the separated constituents are detected by <br /> a detector, which produces an electrical signal proportional to the quantity <br /> of material present This signal is fed to a strip chart recorder and/or <br /> integrator Integrator or recorder output are then used in conjunction with <br /> previously injected standards of known concentrations to identify and <br /> quantitate the chemical constituents present <br /> 8 1 5 2 Calibration Procedures - Minimum calibration protocols for the <br /> field gas chromatography work include the following <br /> 8-4 <br />