Plasma Spectroscopy Analysis Using Thallium Internal Standard
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Solution Overview
Problem
Variations in plasma emission amounts for identical concentrations of heavy metal ions in urine samples due to endogenous substances, particularly creatinine, lead to inaccuracies in quantification using existing methods.
Innovation Solution
A plasma spectroscopy analysis method that involves diluting urine samples with high creatinine concentrations to a range of 75 mg/dL to 180 mg/dL, adding a known concentration of thallium as a control metal species, and using the thallium's plasma emission to correct the analyte metal species' emission, thereby standardizing the measurement and reducing the impact of sample characteristics on quantification accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma spectroscopy is used to quantify heavy metal ions in urine samples, then the quantification process is simplified and rapid, but the accuracy deteriorates due to variations in plasma emission amounts caused by endogenous substances like creatinine
Solution Approach 1:
The patent introduces an internal standard element (thallium) as an intermediary reference substance with known concentration. This internal standard serves as a mediator to compare and normalize the plasma emission signals of heavy metal ions, thereby compensating for variations caused by endogenous substances in the urine sample while maintaining the rapid quantification capability of plasma spectroscopy
Solution Approach 2:
The patent changes the parameter of emission amount by comparing the plasma emission signal of the analyte against the emission signal of the internal standard at known concentrations. This parameter transformation converts absolute emission measurements into relative ratios, eliminating the effect of sample matrix variations and improving quantification accuracy
2Device complexity
If urine samples with high creatinine concentration are analyzed directly, then the sample preparation is simplified, but the measurement precision deteriorates due to suppression of plasma emission by endogenous substances
Solution Approach 1:
The internal standard element acts as an intermediary reference that is added to all samples including those with high creatinine. By comparing the analyte signal to the internal standard signal, the method compensates for emission suppression effects without requiring complex sample preparation to remove endogenous substances
Solution Approach 2:
The method enables the sample matrix itself (including endogenous substances) to serve as part of the measurement system. The internal standard co-experiences the same matrix effects as the analyte, allowing the system to self-correct for variations through ratio calculation, thereby maintaining measurement precision without simplifying sample preparation
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 method improves the accuracy of quantifying mercury or lead in urine samples by standardizing plasma emission, effectively eliminating the effects of endogenous substances and enhancing the reliability of the quantification process.
Implementation Method 1
the urine sample is diluted such that the creatinine concentration is from 75 mg/dL to 180 mg/dL
Implementation Method 2
applying an electric current across a pair of electrodes disposed in the measurement container to concentrate the analyte metal species and the control metal species present in the urine sample in a vicinity of at least one of the electrodes
Implementation Method 3
applying an electric current across the pair of electrodes after the concentration process so as to generate plasma, and detecting emitted light from the analyte metal species and the control metal species arising due to the plasma
Implementation Method 4
detecting emitted light from the analyte metal species and the control metal species arising due to the plasma
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A urine sample (60) assumed to contain mercury or lead is diluted, and then a known concentration of thallium is added to the diluted urine sample (60). The resulting mixture is introduced to a measurement container (10), and an electric current is applied across a pair of electrodes (20, 30) in the measurement container (10) such that the mercury or lead and the thallium in the urine sample (60) are concentrated in a vicinity of one of the electrodes (20, 30). An electric current is then applied across the pair of electrodes (20, 30) to generate plasma, and emitted light from the mercury or lead and the thallium is detected. An analysis emission amount that is a net emission amount at an analysis wavelength that is a wavelength corresponding to the mercury or lead is corrected using a control emission amount that is a net emission amount at a control wavelength that is a wavelength corresponding to the thallium. The corrected value is compared to a calibration curve obtained by advance measurements of known concentrations of the mercury or lead in order to quantify the mercury or lead in the urine sample (60).