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Rare Earth Detection Column | ICP-MS Scheme for Rare Earth Impurities in Neodymium Iron Boron Samples
Date: 2025-12-23Read: 0
In the previous issue, Agilent specifically introduced a scheme for determining rare earth impurity elements in neodymium iron boron alloys using 5800 ICP-OES. Although inductively coupled plasma mass spectrometry (ICP-MS) analysis of rare earth elements has a lower detection limit (~ng/L), some rare earth elements suffer from overlapping interference between oxide/hydroxide mass spectrometry. For example, in neodymium iron boron samples143Nd16O interference159Tb，146Nd16O1H interference163Dy，148Nd16O1H interference165Ho，150Nd16O1H interferes with 167Er. Due to the difficulty of removing neodymium oxide/hydroxide completely in conventional ICP-MS analysis, it can affect the accurate quantification of rare earth impurities in neodymium iron boron samples.
Due to the second ionization energy of rare earth elements ranging from 10 eV to 13 eV, they can undergo secondary ionization in argon plasma, forming a double charge (z=2) and generating a mass spectrometry signal at m/2. Therefore, they can be analyzed159Tb++The163Dy++The165Ho++The167Er++Avoid interference from neodymium oxide/hydroxide during the process.Agilent ICP-MS has a semi mass number analysis function, based on which the content of Tb, Dy, Ho, and Er elements can be analyzed at m/z=79.5, 81.5, 82.5, and 83.5.
Figure 1 Half Mass Mass Mass Spectrometry
Main parameters and conditions of the instrument
Table 1 Main Parameter Conditions of Agilent ICP-MS
parameter |
value |
RF power (W) |
1600 |
Sampling depth (mm) |
6 |
Helium flow rate (mL/min) |
5.5 |
Eight pole bias voltage (V) |
-18 |
Kinetic energy discrimination voltage (V) |
5 |
Interference level test
When conducting interference experiments using optimized instrument and method conditions, analyze and test 100 µ g/mL Nd single standard in He gas mode“159Tb，165Ho，167Er，163Dy "and“79.5Tb，81.5Dy，82.5Ho，83.5The test results of these two groups, Er, and observe the interference level. According to the data results in Table 2, under the dual charge measurement, the interference of hydroxides (Dy, Ho, Er) can be reduced by about 10 times, and the interference of oxides (Tb) can be reduced by more than 50 times. The sum of the interference ratios of Nd on Tb, Dy, Ho, Er is less than 0.004%, which can meet the analysis requirements of rare earth impurity elements in neodymium iron boron.
Table 2 Comparison of Interference Levels under Different Modes (Unit: µ g/L)
79.5Tb |
81.5Dy |
82.5Ho |
83.5Er |
|
Nd（100µg/mL） |
0.736 |
2.088 |
0.204 |
0.809 |
159Tb |
163Dy |
165Ho |
167Er |
|
Nd（100µg/mL） |
44.985 |
23.163 |
1.897 |
8.338 |
Sample analysis results and precision
Dilute rare earth element standard stock solution at a concentration of 10 μ g/mL step by step to prepare a concentration of 0 μg/L、0.2μg/L、1μg/L、2μg/L、10μg/L、200μg/L Draw a calibration curve for the standard solution, test the blank solution 12 times, calculate the instrument detection limit based on three times the standard deviation of the measured concentration result (µ g/L), and multiply the instrument detection limit by the sample pre-treatment dilution factor (DF=5000) to calculate the method detection limit. The detection limit of all rare earth element methods is less than 0.035 μ g/g; At the same time, seven neodymium iron boron measurement solutions were processed in parallel according to the sample processing method. After drawing the calibration curve, the solutions were analyzed, and the sample results and precision of parallel sample measurements were calculated. The data showed that the precision of all element measurements was less than 10%.
Table 3 Detection Limit and Precision
Instrument detection limit |
Method Detection Limit |
content |
precision |
|
µg/L |
µg/g |
µg/g |
% |
|
74.5Sm |
0.004 |
0.021 |
3.36 |
5.56 |
77.5Gd |
0.004 |
0.022 |
21.82 |
2.96 |
79.5Tb |
0.002 |
0.010 |
2.56 |
2.37 |
81.5Dy |
0.007 |
0.035 |
110.72 |
1.31 |
82.5Ho |
0.003 |
0.013 |
1.30 |
3.42 |
83.5Er |
0.002 |
0.008 |
1.82 |
6.51 |
89Y |
0.001 |
0.004 |
2.12 |
1.57 |
139La |
0.001 |
0.004 |
19.63 |
1.63 |
140Ce |
0.001 |
0.007 |
186.54 |
1.32 |
153Eu |
0.001 |
0.004 |
NA |
NA |
169Tm |
0.0005 |
0.002 |
0.06 |
7.27 |
172Yb |
0.001 |
0.004 |
0.35 |
3.33 |
175Lu |
0.001 |
0.004 |
1.64 |
2.18 |
Accuracy testing
After drawing the calibration curve, analyze the solution and add 1 μ g/L of the tested element to one of the samples. Measure the concentration of the added standard and calculate the recovery rate. The results show that the recovery rate of all elements is between 80-100%.
Sample solution |
Solution spiked with 1 µ g/L |
spike recovery rate |
|
µg/L |
µg/L |
% |
|
74.5Sm |
0.66 |
1.54 |
88.2 |
77.5Gd |
4.33 |
5.19 |
86.9 |
79.5Tb |
0.48 |
1.32 |
84.0 |
81.5Dy |
21.77 |
22.70 |
93.1 |
82.5Ho |
0.22 |
1.07 |
84.9 |
83.5Er |
0.36 |
1.16 |
80.1 |
89Y |
0.43 |
1.38 |
94.9 |
139La |
3.92 |
4.87 |
94.9 |
140Ce |
36.98 |
37.96 |
97.5 |
153Eu |
0.002 |
0.97 |
96.5 |
169Tm |
0.01 |
1.01 |
99.9 |
172Yb |
0.07 |
1.06 |
98.5 |
175Lu |
0.33 |
1.31 |
98.4 |
Conclusion
The use of Agilent ICP-MS half mass measurement mode can effectively reduce the interference of oxides and hydroxides of major elements in neodymium iron boron samples, achieving accurate determination of rare earth element impurities in neodymium iron boron under ICP-MS helium gas,And the detection limit of the analytical method is less than 0.035 μ g/g for all elements, the measurement accuracy RSD% is less than 10%, and the spiked recovery rate is 80-120%. This method is accurate and reliable, with the advantage of low detection limit, and is effectively applicable for the analysis and detection of rare earth impurity elements in neodymium iron boron samples.