Agilent Technologies G6600-90006 Special Operating Modes, Using the 255 NCD in Nitrosamine Mode

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Special Operating Modes

Using the 255 NCD in Nitrosamine Mode

By default, the 255 NCD is configured to detect nitrogen. To change from nitrogen to nitrosamine mode, first turn off and unplug the Controller. Remove the cover, find jumper P6 and the positions labelled High Setpoint and Low Setpoint located on the printed circuit board near the left front of the Controller. Move the jumper position from the High Setpoint to the Low Setpoint position. This changes the temperature control range to 350-500 °C to be used for nitrosamine analysis. Refer to see Figure 9 on page 37 for a schematic drawing of the 255 NCD in nitrosamine mode.

Hydrogen is not used in the nitrosamine mode. Turn off and disconnect the hydrogen inlet gas. Using the supplied tee, couple the oxidant outlet with the two Burner inlets. Use of oxygen is recommended at 5-10 mL/min because the Burner can easily be cleaned by raising the Burner temperature to about

900-1000 °C in flowing oxygen. Alternatively, helium or argon can be used, however, these gases will not permit in situ cleaning at elevated temperature.

The presence of catalyst in the quartz combustion tube will generally yield the highest sensitivity for nitrosamines. However, for some sample types that contain potentially interfering nitrogen compounds, such as nicotine, it may be desirable to remove the catalyst to obtain better selectivity. This is achieved by removing the quartz combustion tube and using a straight 1/16" rod or tube to push the catalyst out of the tube (save the catalyst for reuse or recovery as it contains 90+% platinum). Replace the combustion tube and optimize the burner temperature as desired (in general it is desirable to increase the pyrolysis temperature by 50-100 °C when the catalyst is not used). Refer to the “Tube Replacement for the NCD” on page 102 for additional instruments with regard to tube removal and replacement.

Using the SCD in High Sensitivity Mode for Nonhydrocarbon Gaseous Samples

There are circumstances in which it may be desirable to operate the SCD in a non-typical manner. These could include the analysis of very low levels of sulfur species in a nonhydrocarbon gas matrix, such as helium, carbon dioxide, or even hydrogen. It should be possible to measure low ppb or high ppt levels of sulfur species.

In the case of a hydrogen matrix, the sample matrix itself can suffice as the lower source of hydrogen for Dual Plasma operation in a non-chromatographic mode. For instance, a flow rate of nominally 20 SCCM of the sample, a hydrogen calibration gas and a “clean” hydrogen source can be alternately introduced to the Burner. The sample and calibration gas would be introduced into the normal column connection. The side port of the splitter fitting would be plugged and the clean hydrogen source would be plumbed to the lower hydrogen inlet port. The upper hydrogen and air flow rates would be adjusted to nominally 30 and 65 SCCM, respectively.

In the case of nonhydrocarbon gaseous samples, the potential for coking is not a concern, so a Dual Plasma is not necessary. Some improvement in sensitivity

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Operation and Maintenance Manual

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Contents Operation and Maintenance Manual Acknowledgements WarrantySafety Notices Manual Part NumberEnglish WA R N I N GIs not in use Español Français Deutsch Italiano Dutch Veiligheidsvoorzieningen niet meerFollowing symbols are used on the equipment Contents Installation OverviewFront Panel Controls and Initial Startup OperationMaintenance Pump MaintenanceTroubleshooting IndexOperation and Maintenance Manual Introduction Operation and Maintenance Manual System Description Specifications Technical Information 355 SCDTechnical Information 255 NCD Physical Specifications Power requirementsVoltage Theory of Operation Sulfur Chemiluminescence DetectorNitrogen Chemiluminescence Detector Dual Plasma Controller Dual Plasma Burner with the 355 SCDDescription of Major Components Dual Plasma BurnerCross-Section of the Dual Plasma Burner for the 355 SCD Cross-Section of the Dual Plasma Burner for the 255 NCD Ozone Generator Chemiluminescence Reaction Cell and Photomultiplier Tube355 SCD Left Side 355 SCD Right Side 255 NCD Left Side View Pressure Transducer Vacuum PumpFID Adapter Optional Chemical TrapOil Coalescing Filter NCD Reaction CellNCD Photomultiplier Tube and Cooler Schematic for 355 SCD Schematic for 255 NCD, in Nitrogen Mode Schematic for 255 NCD, in Nitrosamine Mode Operation and Maintenance Manual Installation Overview Power Requirements Selecting a LocationEnvironmental Considerations Combustion Gas RequirementsTwo-stage pressure regulators Venting Gases Required Installation Tools Unpack and Inspect the InstrumentSet Up the Vacuum Pump Installing the Edwards RV5 Pump Oil-Sealed Vacuum PumpWA R N I N G Ard RV5 Oil-Sealed Vacuum Pump and Associated Traps Front Side RV5 Oil- Sealed Vacuum Pump and Associated Traps Top Setting the Gas Ballast Position RV5 Installing the Welch Dry Piston Vacuum Pump Operation Notes Welch Pump Welch Dry Piston Pump Operation and Maintenance Manual Connect the Power Cord SCD 230 V Unit Rear Panel DiagramInstall the Dry Compressed Air or O2 Supply Install the Signal Output Cables Install the Dual Plasma Burner Additional informationInstall the Dual Plasma Controller Dual Plasma Controller Rear PanelInstall Column Connections Capillary ColumnsPacked Columns and Columns with an Outside Diameter 0.8 mm Install the Transfer Line Front Panel Controls and Initial Startup Power Controls Detector Front Panel ControlsSignal Controls Display Output ControlsDual Plasma Controller Controls Dual Plasma Controller Front PanelInitial Startup Vacuum TestRecorder Test Detector Interface Setup Initial CheckoutIgnition Operation Start-Up Procedure Column Bleed Detector OperationDetector Stability and Response CokingContaminated Gases Fluctuating PressuresTypical Operating Conditions Typical Operating ConditionsDetection Limits Expected Detection Limits for Chromatographic ConditionsInstrument Shut-Down Daily ShutdownComplete Shutdown Using the 255 NCD in Nitrosamine Mode Special Operating ModesOperation and Maintenance Manual Operation and Maintenance Manual Maintenance Pump Maintenance Operating Life of Components for Edwards RV5 Vacuum PumpCleaning the Detector Changing the Oil Mist Filter RV5 Reaction Cell Cleaning EquipmentReaction Cell, PMT Housing and PMT Socket WA R N I N G Flow Sensor Calibration Detector Sensitivity MDLSCD Proper Ferrule Orientation to the Large Ceramic Tube Orientation of the Double Taper Ferrule Tightening the Heater Swivel Nut Operation and Maintenance Manual NCD Proper Ferrule Orientation to the Large Quartz Tube Burner Assembly Detail Tube Replacement for the SCD Positioning the Upper Tube in the Union Fitting 100 Operation and Maintenance Manual Operation and Maintenance Manual 101 Tube Replacement for the NCD Operation and Maintenance Manual 103 NCD Tube Replacement Detail Troubleshooting Solving Detector Problems Vacuum Pump Fuse Power ProblemsDetector Fuse Dual Plasma Controller FusesFuse Positions on the Power Supply Board Ozone Generation Problems High Voltage TransformerPlugged Restrictor Lines Response Problems Temperature Reading Problems Diagnosing General Problems Troubleshooting Detector IssuesDetector gases Troubleshooting Pump Issues Troubleshooting Burner Issues Index Agilent Technologies, Inc
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