This window displays when Manual
Tune > Parameters is selected.
Select to open the valve and admit PFTBA tuning compound into the analyzer chamber. Deselect to close the valve. The following operations automatically turn the MS OFF and set the system to leave the Cal Valve closed when MS is next turned ON.
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MS On |
Turns on the MS, but does not collect data. |
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MS Off |
Turns off the MS. The MS will automatically turn off if 5 minutes has elapsed without collecting any data. |
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Ion Polarity |
Displays the polarity of the electronics based on the type of ionization mode being used. This information comes from the tune file. |
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Although the emission current from the filament may be set, the default setting is recommended as optimal. The higher the current, the more electrons are emitted. If the emission current is set low, it will result in less ionization, which may reduce sensitivity. If the current is set high, there will be more fragmentation of the sample, and the filament will burn out more quickly. |
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Sets the ground-referenced energy of the electron beam in eV. 70 eV is strongly recommended for EI mode. The voltage should typically be set to 70 eV to produce classical spectra of organic molecules. Reducing the voltage will result in softer ionization (less fragmentation) of organic molecules and a noticeable reduction in sensitivity. As the voltage is decreased, overall sensitivity is decreased in a linear manner. Most organic molecules have ionization potentials between 10 and 20 eV, so 10 eV is a practical minimum electron energy if the production of the ions is the objective. When reducing the voltage, do not exceed the emission current shown in the following table or filament life will be shortened.
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Set this value to 1 to select the top filament and set this value to 2 to select the bottom filament. This setting allows replacement of a bad filament with an installed spare without opening the analyzer. |
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Sets the voltage of the repeller (part of the ion source). The repeller is a positive voltage that repels the ions, pushing them out of the source. If the voltage is set too low, too few ions will leave the source, resulting in poor sensitivity and poor high mass response. If it is set too high, too many ions at too high a velocity will leave the source. This results in precursors (poor mass filtering) and poor low mass resolution. |
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Sets the voltage of the ion focus lens (part of the ion source). Ion focus affects ion abundance. Generally, the offset is ramped during tuning to find the ion focus offset that results in the best ion abundance. |
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Sets the entrance lens gain, a value used to determine a mass dependent voltage that is applied to the entrance lens. The entrance lens is the final lens through which ions pass before they enter the mass filter. During tuning this voltage is ramped over mass 1 for stune or mass 1 and 3 for atune to find the settings that provides the maximum abundance. |
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Sets a fixed voltage that is added to the source entrance lens voltage. Increase the voltage to increase abundance of ions at low masses without substantially decreasing the abundance of ions at high masses. |
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Sets the voltage of the source ion body. |
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Displays the actual and setpoint temperature of the ion source. The temperature may be set in the Manual Tune Parameters window. See Analyzer Temperature Guidelines (597x) for restrictions and recommendations. |
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Sets the value of the mass axis gain, which is a multiplicative factor used in the equation to calibrate the mass axis. Mass axis gain adjusts the reported value of a given mass to the correct number. The mass that appears in a report has had a linear correction applied to it. This may be thought of as a calibration curve where the uncorrected mass is plotted along the x axis and the reported mass is plotted along the y axis. The calibration curve is a straight line with a slope that is proportional to the mass gain. Mass gain has a greater effect on mass assignments at the high end of the mass scale than at the low end. |
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Sets the value of the mass axis offset, which is added to the Mass Gain to calibrate the mass axis. |
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Affects the width of the mass peaks by adjusting the ratio of dc voltage to RF voltage on the mass filter. A higher value gives narrower peaks, but affects peaks at high masses more than those at low masses. |
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| Width offset | Affects the width of the mass peaks by adjusting the ratio of dc voltage to RF voltage on the mass filter. A higher value gives narrower peaks at all masses. | ||||||||||||||
Width 219 affects the width of mass peak at 219 m/z. The value entered for this parameter is approximately the value of the correction applied at mass 219. For instance, if a peak width adjustment has been performed and the values are:
then entering a value of -0.03 for the Wid219 parameter, followed by a peak width adjustment, should result in the peak widths of all masses being set very close to 0.60 m/z.
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Sets the polarity of the direct current applied to the quadrupole mass filter. This parameter is set at the optimum polarity at the factory and should not be changed for normal use. |
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Set this value to On to enable the high energy dynode and Off to disable it. |
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Sets the voltage of the electron multiplier (part of the detector). Increasing the voltage increases the signal sensitivity. Increasing EM Volts increases the abundance by raising the signal coming out of the mass spectrometer. Raising EM Volts also decreases the life span of the multiplier. Operate the multiplier at the lowest voltage that provides adequate sensitivity. To prolong its life, turn off (0 volts) the multiplier (and all other voltages) until the solvent peak has passed. (If a solvent delay is specified, these voltages are turned off until the end of the solvent delay). For the same reason, reduce EM Volts if you are analyzing a highly concentrated sample or are operating in CI mode. |
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Sets the voltage of the extraction lens (part of the EXT ion source). |
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Displays the actual and setpoint temperature of the quadrupole. The temperature may be set in the Manual Tune Acquisition Parameters window. See Analyzer Temperature Guidelines (597x) for restrictions and recommendations. |
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Source temperature (°C) |
Displays the actual temperature of the source. |
Turbo speed (%) |
Displays the actual speed of the turbo pump. |
Quad temperature (°C) |
Displays the actual temperature of the Quadrupole. |
Quad manifold (Torr) |
Displays the actual pressure of the analyzer. |