• No : 4756
  • Displayed Date : 2021/01/12 10:11
  • Updated DTM : 2021/01/12 15:39
  • Print

(GCMS) Starting the Instrument

(GCMS) Starting the Instrument
Category : 

Answer

This section explains how to start up and shut down an installed instrument.
For instruments that do not have a CID, skip that section.
 
1. Turn on the carrier gas.
  1.1 Carrier gas
    1) After verifying that the carrier gas is helium with a purity of at least 99.995 %, make sure that the carrier gas lines are connected as shown in the diagram below.
    2) Open the main valve of the carrier gas cylinder.
    3) Ensure that the supply pressure, or the pressure at GC carrier gas inlet, is 300 - 980 kPa (about 3 - 9.8 kgf/cm2).
    NOTE: When changing gas cylinders, make sure that there are no leaks from the connection at the gas cylinder.
    
 
  1.2 CID gas
    1) After verifying that the CID gas is argon with a purity of at least 99.99 %, make sure that the CID gas lines are connected as shown in the diagram below.
    2) Open the main valve of the CID gas cylinder.
    3) Ensure that the supply pressure is 350 - 450 kPa (about 3.5 - 4.5 kgf/cm2).
    NOTE: When changing gas cylinders, make sure that there are no leaks from the connection at the gas cylinder.
 
2. Confirm the insert
  Inspect the injection port glass insert using the following procedure to determine whether the glass insert is appropriate for the application.
    1) Turn the lever counterclockwise while holding the injection port. Raise the injection port slowly.
   
    CAUTION: Raise the injection port slowly by left hand to prevent damage of glass insert.
    CAUTION: Pay attention not to damage the installation surface of O-ring on the injection inlet.
    2) Remove the glass insert with forceps, and verify that it is appropriate for the application. Refer to the figure below. Check the silica wool to make sure that it is clean and positioned properly.
 
    3) If the silica wool is contaminated, remove the wool, and clean or replace it. Pack an appropriate amount of clean silica wool at the specified location. For split injection this is about 10 mg and for splitless about 4 mg.
    4) Install the glass insert and O-ring as described below. Refer to the figure of the upper injection port assembly as necessary.
      a) Temporarily slide the O-ring onto the glass insert so that it is about 4 mm from the top, as shown in the diagram below. Guide the glass insert into the injection port until it touches the bottom. The O-ring will be about 3 mm from the top of the insert when properly positioned.
      b) Install the injection port fitting into the groove.
      c) Turn the lever clockwise while holding the injection port.
   
 
3. Install the column holder and capillary column.
  Attaching the Column Hanger
  Attach the column hanger to the connecting holes as follows:
    1) Squeeze the tabs at the top of the hanger so the ends of the hanger can be inserted into the connecting holes. The standard column mounting position is on the back side of the hanger. When connecting two columns, mount one in front and the other in back.
   
 Connecting the Capillary Column to the Injection Port
    NOTE: The ClickTek connector, one of the GC-2030 optional parts, cannot be used for the GCMS NX series.
    1) Push the capillary column through the Vespel ferrule and nut. Refer to Figure “Using the Column Fitting Jig”.
    2) Insert the end of the capillary column into the column fitting jig (P/N S225-01453-95) of Tool Kit (option), so that the capillary column protrudes about 1 cm from the end of the jig as indicated in Figure “Using the Column FItting Jig”Secure it by tightening the nut. Cut the protruding end of capillary column.
    3) Mark the capillary column beneath the tightened nut with tape as shown in Figure “Making the Column with Tape”.
    4) Remove the capillary column from the jig without moving the tape, and wipe the capillary column with acetone. Insert the column into the injection port and secure it by hand tightening the nut. If the ferrule is new, use the wrench to turn the nut an additional full turn. If the ferrule has been previously used, use the wrench to tighten the nut by turning it 20 to 40 degrees.
    5) Remove the tape used to mark the column.
 
    Vespel ferrule:
      Parts Number: 670-15003-03(for 0.25 mm column) (option)
      Parts Number: 670-15003-04(for 0.32 mm column) (option)
      Parts Number: 670-15003-07(for 0.53 mm column) (option)
    Column mounting jig: Parts Number: 225-01453-95 (option)
    Nut: Parts Number: 670-11009 (option)
    Capillary column cutter: Parts Number: 221-50595-91 (option)
 
    
    NOTE: A graphite ferrule is crimped by the jig, so that it is attached to the column, whereas a Vespel ferrule is not crimped and will slide on the column. To ensure proper positioning of the column, mark the column beneath the Vespel ferrule and nut with tape. Ensure that the tape is removed after installation.
   
 
  Connecting the capillary column to the MS
    1) Push the capillary column through the Vespel ferrule and nut. Refer to Figure “Using the Column Mounting Jig”.
    2) Insert the end of the capillary column into the column fitting jig (P/N S225-01453-94) of Tool Kit (option), so that the capillary column protrudes about 1 cm from the end of the jig as indicated in Figure ”Using the Column Mounting”. Secure it by tightening the nut. Cut the protruding end of capillary column.
    3) Mark the capillary column beneath the tightened nut with tape as shown in Note.
    4) Remove the capillary column from the jig without moving the tape, and wipe the capillary column with acetone. Insert the column into the MS interface and secure it by hand tightening the nut. If the ferrule is new, use the wrench to turn the nut an additional full turn. If the ferrule has been previously used, use the wrench to tighten the nut by turning it 20 to 40 degrees.
    5) Remove the tape used to mark the column.
    
    NOTE: To prevent background noise, always use a Vespel ferrule to connect the column to the MS. A graphite ferrule is crimped by the jig, so that it is attached to the column, whereas the Vespel ferrule is not crimped and will slide on the column. To ensure proper positioning of the column, mark the column beneath the Vespel ferrule and nut with tape. Ensure that the tape is removed after installation.
   
    NOTE: A driftpin is provided in the tool kit (optional) to maintain nuts (SSNE 16/012) used to mount capillary columns.
    A driftpin is provided to remove the ferrule lodged inside the mounting nut (SSNE16/012) when the nut is re-used. In order to reduce wear on the interface screw, only reuse it two or three times..
   
 
4. Turn on the instrument.
    1) Ensure that breaker controlling the instrument power supply is on, and turn on the GC main power switch.
    2) Turn on the computer, monitor and printer, and start Windows.
    3) Turn on the MS. The power LED in the upper left corner of the MS will illuminate.
 
5. Start GCMSsolution.
    1) Double-click the [GCMS Real Time Analysis] icon. The [Login] dialog box is displayed.
    2) Enter your user name and password. The first time that the software is accessed, use the default user name "Admin" and leave the password blank.
      After entering the necessary information, click the [OK] button.
      The [GCMS Real Time Analysis] program starts.
 
6. Start the vacuum system
  CAUTION: If the instrument has been shut down for an extended period of time and the ambient temperature is low, the rotary pump oil may become very viscous. When the oil viscosity is too high and the rotary pump is operated, an excessive load is placed on the rotary pump motor. The breaker for the main power supply may trip, shutting down the instrument.
  When the instrument has been turned off and maintained in a cold environment, increase the ambient temperature and start up the instrument after the rotary pump temperature is at least as high as the minimum temperature specification (18 °C).
  CAUTION: Verify that the knob on the MS front panel door is tight before starting the vacuum system.
  CAUTION: Do not tighten the knob on the MS front panel door after starting the vacuum system. Otherwise, it may be impossible to loosen the knob after the instrument is shut down.
  CAUTION: When replacing a column with one of a larger internal diameter, a large volume of carrier gas may flow into the MS and prevent the vacuum system from starting. Before starting the vacuum system, adjust the pressure for the carrier gas and make sure that the flow into the column is less than 15 mL/min (less than 5 mL/min for CI/NCI).
    1) Click the [Vacuum Control] icon in the Assistant Bar. The [Vacuum Control] dialog box is displayed
    
    2) Click [Option].
    The [Option] sub-window is displayed.
   
    3) Set the items to execute.
    See below for details of each item.
   Vacuum Restart Mode: Specifies whether or not to automatically start the vacuum system when the power distribution recovers after temporary system shutdown caused by power outage, etc. Note, however, that the vacuum system will not start regardless of the setting, if the vacuum system has already stopped before instrument shutdown due to power outage.
    Vacuum Leak Check: Allows for checking vacuum leakage by comparing the intensities of nitrogen (m/z 28) and water (m/z 18), after automatic start of the vacuum system is completed. The guideline value for the intensity ratio varies depending on the accessory/peripheral equipment.
    NOTE: The setting is available only when the ion source is EI and the carrier gas is He. In other cases, see "Checking for Leaks" to check for vacuum leakage.
      Set the value using the following guideline.
      ・AOC-20, AOC-5000/6000: Intensity ratio of 2
      ・Other accessory/peripheral equipment: Intensity ratio of 5
      NOTE: When using the advanced flow technology system (such as detector splitting system or backflush), the intensity for m/z 28 may be larger than when using the standard system. Therefore, it is not recommended to use this function for leak check.
    Stabilization Waiting: Auto-tuning is usually executed to stabilize the vacuum degree of MS for about two hours for qualitative analysis and four hours for quantitative analysis after the vacuum system start. This item allows for setting the waiting time for stabilization.
    4) Click [OK].
      The [Option] window is closed.
    5) Click the [Auto Startup] button.
      The Startup indicator flashes, the progress bar is displayed, and the vacuum system startup sequence initiates. The various components start up in sequence, as noted in the progress bar, and when the vacuum system is ready for operation, "Vacuum Completed." is displayed.
      When the vacuum leakage check or stabilization waiting is set, the operation is automatically executed upon completion of the automatic start of the vacuum system.
    
    6) Check the result.
    
    NOTE: When the result of vacuum leakage check fails, it is possible that there is an air leak.
      Search for the location of the leak, referring to  "Checking for Leaks".
    NOTE: After the vacuum system starts operating, the degree of vacuum may temporarily be insufficient, so a "Vacuum level deterioration. Ion gauge is immediately switched off." message may be displayed. In this case, wait about 1 hour. Then open the [Monitor Settings] window, and in the [Higher Vacuum] area, click (ion gauge). If no error message is displayed, you may use the system as is.
    7) Close the [Vacuum Control] dialog box.