Abstract
This paper studies the interference of aluminum,such as iron, manganese, copper, zinc, magnesium, titanium, silicon, gallium, adopts the matrix interference correction and uses the interference coefficient method, and compares the method with the chemical method, with satisfactory results. The recovery rate of the method is between 92.9%and 105%, and the precision is between 0.8 2%and 2.32%. The method is fast, simple and reliable, and is suitable for the daily inspection of import and export aluminum ingots.
Key words inductively coupled plasma atomic emission spectra,aluminum ingot, matrix matching method, interference coefficient method.
Preface
China is one of the worlds main importer,and aluminum ingots as an important industrial raw material, widely used in machinery, aviation, profile alloy, food packaging, wire, cable, refractory, catalyst carrier, flame retardant, precision electronic industry and advanced science and many other industrial and scientific research departments, the aluminum ingot impurity content will directly or indirectly affect the conductive material conductive and thermal conductivity, the quality and performance of various profile of alloy, refractory and catalyst carrier and flame retardant properties and use of[1], so the good import and export of aluminum ingot quality is particularly important. At present, the common methods for the determination of impurity elements in aluminum ingots include atomic absorption spectroscopy TISH1306,photometry and polarography TISH1352-TISH1365, emission spectrum TISH1303, photoelectric spectroscopy TISH1305, chemical ISO79 3-795 and national standard GB6987, and some of these methods are single element analysis with complicated analysis procedures and long cycle. No direct determination of impurity elements in aluminum ingot by ICP-AES method has been reported before. Due to the high excitation temperature of ICP light source, rich spectrum lines, a wide range of optional spectrum lines, and can be analyzed at the same time, has been widely used in the analysis test, but also in order to adapt to the actual needs of fast and accurate import and export test of aluminum ingot, so we use ICP-AES studied the method of simultaneous determination of eight impurity elements in the aluminum ingot, used the matrix matching method for matrix interference correction,and deducted the analytical deviation caused by spectral interference between elements. The recovery rate was between 92.9% and 105%, and the relative standard deviation is 0.82%-2.32%. The ICP-AES method was compared with other chemical methods. The results showed that this method is fast, simple and accurate, which has important practical meaning for the spectral analysis of daily inspection of import and export aluminum ingot.
Experimental section
Instrument and apparatus
Type LEEMAN PS3000 ICP-AES, resolution 0 .0075 nm, three-channel peristaltic pump; Sample increase amount: 1.0 mL / min; integration time: 3-5s;
High- frequency oscillation generator, frequency of 40 . 6 8 MHz;
Double-platinum net atomizer;
Spectral system: middle step grating, focal length of 0.75m;
Observation height: automatically make Peak Both of manganese (259 .373nm) with the instrument, and adjust the best observation area of manganese, as a compromise observation height;
Method: single sequential scanning, multiple simultaneous determination.
High- frequency oscillation generator, frequency of 40 . 6 8 MHz;
Double-platinum net atomizer;
Spectral system: middle step grating, focal length of 0.75m;
Observation height: automatically make Peak Both of manganese (259 .373nm) with the instrument, and adjust the best observation area of manganese, as a compromise observation height;
Method: single sequential scanning, multiple simultaneous determination.
Working conditions
Coupling power: 1.0kW, argon cooled gas flow: 14L / min, argon auxiliary gas flow: 0.2L / min, nebulizer pressure: 2.744 105 Pa (40 PSI).
Reagent
Hydrochloric acid is analytically pure;
The experimental water is distilled water and ion exchange;
High purity aluminum (Al-05) : purity of 99. 999% ( made by Shenyang Standard Sample Research Institute);
Standard sample ( Al- 00 ) : the purity is 99. 7 39 9 % ( made of Shandong Metallurgical Design and Research Institute);
Fe, Mg, Cu, Zn, Al, Ti, Si, Mn, Ga reserve solution: all are national standard solutions with a concentration of 1000 or 500 μg / mL;
Fe, Mg, Cu, Zn, Ti, Si, Mn, Ga analytical standard solutions, all series concentrations of 0.00,1.00,2.00,5.00,10.00 μg / mL, each standard solution containing aluminum matrix matching the analyzed samples, i. e. 1g of aluminum per 100 mL of the analytical standard solution.
The experimental water is distilled water and ion exchange;
High purity aluminum (Al-05) : purity of 99. 999% ( made by Shenyang Standard Sample Research Institute);
Standard sample ( Al- 00 ) : the purity is 99. 7 39 9 % ( made of Shandong Metallurgical Design and Research Institute);
Fe, Mg, Cu, Zn, Al, Ti, Si, Mn, Ga reserve solution: all are national standard solutions with a concentration of 1000 or 500 μg / mL;
Fe, Mg, Cu, Zn, Ti, Si, Mn, Ga analytical standard solutions, all series concentrations of 0.00,1.00,2.00,5.00,10.00 μg / mL, each standard solution containing aluminum matrix matching the analyzed samples, i. e. 1g of aluminum per 100 mL of the analytical standard solution.
Pre ple pretreatment
Weigh 1g aluminum ingot sample (accurate to ± 0.0001g) into a 250mL beaker, add 15mL of concentrated hydrochloric acid and 15 mL of water, heat to the sample to dissolve, move to a 100 mL of volumetric bottle to scale, shake well and wait to be measured. Make the blank along with the test sample.
Results and Discussion
Selection of the analytical line wavelength
The standard solution and blank solution of the elements to be tested are scanned at each wavelength to obtain the scan profile map of these elements at these wavelength, and then input the interference element solution to obtain the correspondings can peak shape map. Computer store these maps and display them simultaneously. From the outline and intensity values of the spectrum line and background, we can intuitively see the type and degree of interference, and the appropriate analysis line and background correction position can be easily selected.
Table 1 element analysis line wavelength, buckle background point
| element | wavelength (nm) | Background BKP 1 (nm) | Background BKP 2 (nm) |
| M n | 259 ．373 | 259 ．352 | 259 ．394 |
| Mg | 279 ．079 | 279 ．057 | 279 ．101 |
| Cu | 327 ．396 | 327 ．370 | 327 ．422 |
| Ti | 338 ．376 | 338 ．349 | 338 ．403 |
| Zn | 213 ．856 | 213 ．831 | 213 ．881 |
| Fe | 238 ．204 | 238 ．185 | 238 ．223 |
| Si | 251 ．611 | 251 ．582 | 251 ．640 |
Selection of ICP working parameters
The change of generator power and ato mization gas flow has different effects on the reliability ratio of different spectral lines. In order to detect multiple elements simultaneously, the compromise operating conditions areadopted.
Detection limit, recovery rate and precision of the method
With 15% HCl as the blank, repeated measurement for 11 times, with 3 times the standard deviation as the detection limit, as shown in Table 2.
Table 2 Detection limit, recovery rate and relative standard deviation of the method
| element | Limit of detection(μg/ mL) | Percent recovery(%) | Relative standard deviation(%) |
| Mn | 0 ．0021 | 104 ．0 | 0 ．91 |
| Mg | 0 ．0711 | 92 ．9 | 2 ．32 |
| Cu | 0 ．0264 | 100 ．0 | 1．91 |
| Ti | 0 ．0009 | 100 ．0 | 0 ．74 |
| Zn | 0 ．0006 | 105 ．0 | 1．06 |
| Fe | 0 ．0045 | 104 ．8 | 0 ．89 |
| Si | 0 ．0222 | 102 ．9 | 1．24 |
| Ga | 0 ．0006 | 96 ．7 | 0 ．82 |
Interference situation
In this experiment, the matrix matching method was used to eliminate the error of the analysis results caused by Al matrix interference.
Elimination of matrix interference
In this experiment, the matrix matching method was used to eliminate the error of the analysis results caused by Al matrix interference.
Elimination of interference between impurity elements
Due to the relatively low content of Mn, Mg, Ti, Cu, Ga, and Zn in the aluminum ingot, their phases were found in the interference test
It basically does not affect each other, while the content of Si and Fe is relatively high,but Si basically does not affect the determination of impurity elements, so the influence of Fe on the determination of impurity elements is mainly considered.It is known from the interference condition test that the Fe above 10μg/mL has an influence on the determination of Mn and Zn, and the interference coefficient method must be used to deduct the analysis deviation caused by the spectral interference between the elements, so as to obtain a more accurate analysis results.
Table 3. Interference coefficient between the elements
| To be tested elements | Interference elements | Interference factor (10-3) |
| Zn | Fe | 0 ．397 |
| Mn | Fe | 1 ．048 |
The interference coefficient refers to the value measured by the pure solution of the interference element per unit concentration at the wavelength of the element to be measured. Correct the treatment of the spectral interference of the measured elements by measuring the interference coefficient, as shown in Table 3.
Comparison of test results of ICP-OES and chemical methods
The actual sample and the standard samples were determined by ICP-OES method and chemical method,respectively.The test results are shown in Table 4.As shown in Table 4,the determination results of the two methods are basically consistent.
Conclusion
This method is fast, simple, accurate and reliable inspection results, and can meet the needs of daily inspection and analysis of impurity elements in the import and export aluminum ingot.
Table 4 Comparison of ICP-OES and chemical methods
| Sample number Element | ICP-OES method(%) | Standard value (%) | Standard value(%) |
| Mn | 0.0026 | 0.0022 | 0.0025 |
| Mg | 0.0013 | 0.0012 | 0.0014 |
| Cu | 0.0027 | 0.0027 | 0.0027 |
| Ti | 0.0015 | 0.0015 | 0.0015 |
| Zn | 0.0042 | 0.0040 | 0.0040 |
| Fe | 0.1362 | 0.135 | 0.13 |
| Si | 0.1214 | 0.120 | 0.118 |
| Ga | 0.0290 | --- | 0.03 |
| Mn | 0.0023 | 0.0022 | --- |
| Mg | 0.0062 | 0.0060 | --- |
| Cu | 0.0010 | 0.0009 | --- |
| Ti | 0.0006 | 0.00059 | --- |
| Zn | 0.0011 | 0.0016 | --- |
| Fe | 0.2444 | 0.246 | --- |
| Si | 0.0891 | 0.075 | --- |
| Ga | 0.0068 | 0.0081 | --- |
| Mn | 0.0023 | 0.0023 | --- |
| Mg | 0.0060 | 0.0060 | --- |
| Cu | 0.0012 | 0.0011 | --- |
| Ti | 0.0006 | 0.0006 | --- |
| Zn | 0.0012 | 0.0016 | --- |
| Fe | 0.2394 | 0.242 | --- |
| Si | 0.0885 | 0.077 | --- |
| Ga | 0.0066 | 0.0078 | --- |
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