Automated Direct Insertion Probe for Finnigan TRACE MS Mass Spectrometer from Thermo Electron Corp.
Figure 1 - AutoProbe System Attached to the Thermo Finnigan TRACE MS from Thermo Finnigan
The AutoProbe is software controlled and fully integrated within the Thermo Finnigan Xcalibur MS software. A series of PC windows are integrated into Xcabibur to permit the setup of the AutoProbe and the setup of the operational parameters for the AutoProbe. All parameters and methods are saved as part of the Xcalabur methods. The AutoProbe is set up in Xcalibur as an accessory instrument in the Instrumentation Configuration Window. The method parameters for the operation of the AutoProbe, including ramp rates and times of other system parameters, are entered into data screens controlled within the Xcalibur system software.
AutoProbe Software and PC Control
The AutoProbe System has four levels of software that control its entire operation. SIS developed software for the first three levels. The four levels include:
(1) Embedded Software - This resides on the embedded C-programmable microprocessor controller inside the AutoProbe instrument. It directly controls the various hardware components of the AutoProbe, including the servo controller for the linear actuator, the DEP filament current controller, the isolation and rough-pump valves, the vacuum gauge sensor, and the pneumatic valves for the ball valve.
(2) PC-based Instrument Control Software - This controls the AutoProbe instrument from the PC. It does this by communicating with the embedded software (1) via a serial communications link. The PC software sends commands (such as sample run requests) to the embedded software and reads back status data such as the filament current, vacuum readings, the probe position, and operating states. C++, wxWindows, and COM technologies were used. CTC developed their own software for controlling the autosampler. In a typical operation, this layer of software is transparent to the user.
(3) Virtual Instrument Modules - Each instrument of the AutoProbe System is associated with a plug-in module called an "Xcalibur virtual instrument (VI)." These virtual instruments allow instrument vendors to integrate their own instrument control software (2) into the Thermo Finnigan Xcalibur software package (4). Virtual instruments can be thought of as (software) abstractions of instrument hardware. They conform to various standards such as how instruments are configured, methods are set up, and instrument operations are synchronized. Therefore, the entire AutoProbe system is seamlessly integrated into Xcalibur according to the Xcalibur instrument model. SIS developed a VI for the AutoProbe, while CTC and Thermo Finnigan provide the autosampler and MS VI's respectively.
(4) System Control and Analysis Software -Thermo Finnigan Xcalibur software integrates the setup and operation of the virtual instruments (3). It provides a uniform interface for setting up methods and sequences, running samples, collecting data, doing library searches, analyzing results, and printing reports. It also provides an Open Access mode of operation.
As a result of this software integration, the AutoProbe is seamlessly integrated into the Xcalibur software package. The AutoProbe is controlled within the Xcalibur screens and the AutoProbe system status is shown in the Xcalibur system screens.
PC Windows for the Operation of the AutoProbe
In order for the AutoProbe system to operate within the Xcalibur system, Xcalibur must know which devices are being utilized. This is determined in the Xcalabur Instrument Configuration Window. For the operation of the AutoProbe, the PAL Autosampler, SIS AutoProbe and MS systems are selected and configured via the window shown below.
Figure 2 - Xcalabur Instrument Configuration Window
The three instruments are added as shown above.
1. TRACE MS (or PolarisQ or TRACE DSQ)
2. PAL Autosampler
3. SIS AutoProbe
Pressing the SIS AutoProbe Icon above and then pressing "Configure". The following window appears. This window is used to select the appropriate serial communication port. clicking "Test" will verify the communication link to the AutoProbe System.
Figure 3 - AutoProbe configuration - select communications port
Selecting the "Advanced" tab on the above window brings up the following window.
Figure 4 - AutoProbe Configuration Window - Advanced AutoProbe Setup
The settings in the Advanced screen will probably not need to be changed, but they can be changed if necessary.
The one value that may need to be changed here is the Filament "Load" Position. This "Load" position adjustment allows you to position the probe directly under the syringe needle during sample loading. If the alignment of the needle is not correct, the linear position of the probe can be adjusted here to position the syringe needle precisely over the center of the DEP probe tip filament coil.
The "Max Rough Pump Injection Pressure" is the vacuum level to which the isolation valve pump must reach before the isolation valve opens and the probe proceeds in to the source. It is recommended that the value of 200 millitorr be used. The next line, "Max Rough Pump Pressure Time" is the time limit that the vacuum pump has to achieve the above set pressure. It is recommended that this time be set to 120 seconds. If the set vacuum pressure is not reached in the operation of the probe within the 120 seconds time (2.0 minutes), the probe will withdraw from the isolation valve and a vacuum leak warning message will be displayed in the status panel of Xcalibur on the AutoProbe Manual control window.
The screen shown below permits the AutoProbe method to be set up and saved. The AutoProbe method consists of 3 heating steps - Solvent Elimination - Sample Analysis - Bakeout.
Figure 5 - AutoProbe Window for entering AutoProbe method parameters
Solvent Elimination. Before the sample is analyzed, a small current can be passed through the DEP filament wire to slightly heat the wire and remove the sample solvent. If solvent removal is not required, then uncheck the "solvent elim." checkbox. This step of solvent removal can be done either in atmosphere (before the probe is injected into the vacuum system), or in the vacuum inside the mass spec (before the probe is mated up against the MS source). If the solvent removal is to be done inside the vacuum, then check the "Do solvent elimination in vacuum" checkbox, otherwise the default is for solvent removal to occur at the sample load position (at atmospheric pressure).
Sample Analysis. The DEP filament wire can be run at a constant current rate or with a ramp. Up to three different ramp steps are available. These multiple current ramps can be used in some applications to separate analytes in a sample based on boiling points. Just check the current steps desired in the boxes on the left.
Good results can be obtained by running the filament at a single ballistic constant high current of between 500 and 900 mA. This will provide for a quick heating and desorption of the samples into the mass spec source in the minimum amount of time. The result will be sharp total ion chromatograms and therefore the highest level of sensitivity.
Bakeout. The bakeout mode is used to clean the DEP probe tip between samples to prevent cross contamination of samples. After sample analysis, the probe retracts about 1.5 inches out of the source and the bakeout method occurs in the mass spec vacuum. Normally an isothermal setting of between 800 and 1000 mA for 15 seconds will thoroughly clean the DEP probe tip wire.
The Manual Control Window permits the control or operation of the AutoProbe manually. In some instances it may be necessary to move the probe against the MS source in order to seal the source tightly or align the syringe needle with the DEP wire coil. This can be accomplished in the Manual Control window.
Figure 6 - PC Window for the Manual Control of the AutoProbe
One of the unique features of the Thermo Finnigan Xcalibur software is the ability to operate the mass spectrometer in an Open Access Mode. The Open Access System permits inexperienced chemists and technicians to submit samples directly to the mass spectrometer for analysis. The samples are then analyzed automatically and the results reported back to the chemist with little or no interaction of the mass spectrometer operator. The results are increased productivity from the mass spectrometer lab with less technical staff requirements.
The AutoProbe was integrated into this Open Access mode of operation within the Xcalibur software system. For a sample to be analyzed, the chemist fills out a simple form on a PC screen including the submitters name and sample name. He then selects a method of analysis from one of several standard methods preestablished by the supervisor. After completing the form, the user is instructed where to place his sample. The samples are then analyzed automatically with no operator intervention. The chemist has the option of having the results e-mailed back to him.
Figure 7 - Operation of the AutoProbe in Open Access
For additional details click onto the detailed descriptive material on the AutoDesorb system below. The application notes below demonstrate the operation of the AutoProbe for the analysis of samples. For additional pricing and ordering information, contact John Manura at Scientific Instrument Services, or call (908) 788-5550 ext: 800.
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Yttria coated filament at start
Yttria coated filament after 16,000 cycles