ICP Emission Spectrometer Photomultiplier Stabilization
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Solution Overview
Problem
The existing ICP emission spectrometers face accuracy issues due to the time required for the photomultiplier's amplification factor to reach a steady state after changes in voltage, leading to temporary poor accuracy in quantitative results.
Innovation Solution
An ICP emission spectrometer with a detector controller that applies an idle voltage and idle voltage application time similar to the analysis voltage and time, ensuring the photomultiplier's amplification factor becomes constant before analysis, thereby ensuring accurate quantitative analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the voltage applied to the photomultiplier is changed to measure a wider range of light intensity, then the measurement range is improved, but the amplification factor does not reach a steady state immediately, causing temporary poor accuracy in quantitative results
Solution Approach 1:
The system applies a predetermined voltage to the photomultiplier tube before sample introduction to allow the amplification factor to reach a steady state in advance. This preliminary action ensures that when the actual measurement begins, the detector is already stabilized, thus maintaining measurement accuracy while enabling the use of different voltage levels for extended measurement ranges.
2Adaptability or versatility
If the voltage applied to the photomultiplier is changed, then the dynamic range is improved, but approximately three minutes to five minutes are required for the amplification factor to stabilize, causing loss of time
Solution Approach 1:
The system applies a predetermined voltage to the photomultiplier tube before sample introduction to allow the amplification factor to reach a steady state in advance. This preliminary action ensures that when the actual measurement begins, the detector is already stabilized, thus maintaining measurement accuracy while enabling the use of different voltage levels for extended measurement ranges.
Solution Approach 2:
The system maintains continuous voltage application to the photomultiplier tube, switching between predetermined voltage levels based on sample concentration expectations. This continuous operation eliminates repeated stabilization periods, as the detector remains in a ready state throughout the measurement process, thereby reducing time loss while maintaining wide dynamic range capability.
3Measurement precision
If multiple samples with different concentrations are prepared to determine the gain calibration curve, then the accuracy of gain determination is improved, but the device complexity and cost increase due to requiring a light source lamp
Solution Approach 1:
The system uses the plasma source itself to generate the spectral lines needed for gain calibration, rather than requiring a separate light source lamp. By utilizing the ICP plasma to produce atomic emission lines at known wavelengths and intensities, the system creates an internal reference that eliminates the need for external calibration lamps, thereby reducing device complexity while maintaining calibration accuracy.
Solution Approach 2:
The ICP plasma source serves multiple functions: it acts as both the excitation source for sample analysis and the reference source for gain calibration. This multi-functionality eliminates the need for separate calibration equipment, reducing device complexity and cost while maintaining the ability to accurately determine gain calibration curves across different concentration ranges.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for quick and accurate quantitative analysis by stabilizing the photomultiplier's amplification factor, reducing the coefficient of variation of measurement results from 1% to 0.2%, ensuring improved accuracy.
Implementation Method 1
an inductively coupled plasma generation unit configured to atomize or ionize an analysis-targeted element using inductively coupled plasma to obtain atomic emission lines
Implementation Method 2
atomize or ionize an analysis-targeted element using inductively coupled plasma to obtain atomic emission lines
Implementation Method 3
a spectroscope configured to detect the atomic emission lines by diffracting light after receiving the atomic emission lines through a light incident window
Implementation Method 4
a detector configured to detect the light passing through the spectroscope
Data Source
AI summary
An ICP emission spectrometer is schematically configured to include an inductively coupled plasma generation unit, a light condensing unit, a spectroscope, a detector, and a controller. The detector includes a photomultiplier and has a detector controller and an input unit. The photomultiplier has voltage dividing resistors, which make an amplification factor not to become constant immediately due to a change in an application voltage applied to the photomultiplier, but the detector controller controls an idle voltage and an idle voltage application time so that a multiplication factor becomes constant, during a period from when analysis conditions are input to the input unit in advance until a sample containing an analysis-targeted element is introduced into the inductively coupled plasma generation unit.