Product Description
ASTM D2622 ASTM D7757 ASTM D6481 MEDXRF spectrometer Monochromatic Excitation Energy Dispersive X-ray Fluorescence Analyzer MEDXRF Light Element Spectrometer
Ultra-low Detection Limits (300s)
Si: 0.7ppm
P: 0.4ppm
S: 0.15ppm
Cl: 0.08ppm
Technology
Monochromatic Excitation Energy Dispersive X-ray Fluorescence (MEDXRF) analysis technology.
High diffraction efficiency logarithmic spiral rotation double-concave (LSDCC) artificial crystal.
High count rate (2Mcps) and resolution (123eV) Silicon Drift Detector (SDD).
Optimized kV, mA, and target material combinations of micro-focus thin beryllium window X-ray tube.
Complies with standards
GB/T 11140
ISO20884
ASTM D2622
ASTM D7039
ASTM D7220
ASTM D7757
ASTM D7536
ISO 15597
ASTM D6481
ASTM D2622 ASTM D7757 ASTM D6481 MEDXRF spectrometer Monochromatic Excitation Energy Dispersive X-ray Fluorescence Analyzer MEDXRF Light Element Spectrometer
Overview
The GA-D240 model Monochromatic Excitation Energy Dispersive X-ray Fluorescence (MEDXRF) light element (Si, P, S, Cl) spectrometer, referred to as the GA-D240 MEDXRF light element spectrometer, is our company's first monochromatic excitation XRF spectrometer. It is developed based on decades of experience in the research of X-ray fluorescence spectrometers, building upon our existing DM series X-ray fluorescence sulfur analyzers, X-ray fluorescence multi-element analyzers, and wavelength dispersive X-ray fluorescence multi-channel spectrometers. It incorporates the following technologies and components, which provide the 50W tube-based energy spectrometer GA-D240 with excellent reproducibility and stability, ultra-low detection limits, and have indeed raised the detection level to a new standard.
Monochromatic Excitation Energy Dispersive X-ray Fluorescence (MEDXRF) Analysis Technology
The detection limit LOD (limit of detection) of an X-ray fluorescence spectrometer refers to the corresponding quantity of three times the standard deviation of the instrumental background signal generated by the matrix blank, that is:
In the formula, Rb represents the background (baseline) count intensity, NN is the count intensity of the low-concentration sample with known concentration CC, and TT is the measurement time. From Equation (1), it can be seen that the detection limit is inversely proportional to the sensitivity (N-Rb)/C(N−Rb)/C and directly proportional to the square root of the background RbRb. To reduce the detection limit with a constant measurement time, it is necessary to increase sensitivity and/or decrease the background.
Figure 1. Schematic diagram of MWDXRF analysis technology
Traditional XRF, whether EDXRF or WDXRF, cannot achieve a lower detection limit mainly because the scattering of continuous bremsstrahlung in the X-ray tube's emission spectrum results in a high continuous scattering background in the fluorescence spectrum.
The Monochromatic Excitation Beam Energy Dispersive X-Ray Fluorescence (ME-EDXRF) analysis technique employs optical components to monochromatize the emission spectrum of the X-ray tube, thereby greatly reducing the continuous scattering background in the fluorescence spectrum. At the same time, it minimizes the reduction, or even enhances if possible, the intensity of the monochromatic line or narrow energy band of the X-rays required for excitation, thus significantly lowering the detection limit. Compared to traditional EDXRF, it has reduced the detection limit by 1 to 2 orders of magnitude, and it is also much lower than that of high-power (e.g., 4kW) WDXRF.
Figure 2. XRF Spectrum of the Sample
ASTM D2622 ASTM D7757 ASTM D6481 MEDXRF spectrometer Monochromatic Excitation Energy Dispersive X-ray Fluorescence Analyzer MEDXRF Light Element Spectrometer
High diffraction efficiency logarithmic spiral rotation point-to-point focusing artificial monochromatic crystals
There are many methods to monochromatize the emission spectrum of an X-ray tube, including the filter method, secondary target method, and diffraction method. Among them, the doubly curved crystal (DCC) used in the diffraction method is the most effective and efficient for monochromatization.
Diffraction must satisfy Bragg's Law:
nλ=2dsinθ (2)
That is to say, the wavelength of the rays emitted from the source must meet Equation (2) to be diffracted, thus providing it with excellent monochromatization. Moreover, because the DCC can focus a point source, it has a large collection solid angle, which results in extremely high efficiency. Additionally, focusing also allows for a very small spot size on the sample, enabling a small-area semiconductor detector such as Si-PIN or SDD to receive most of the fluorescent rays from a smaller surface area of the sample. This means that the DCC also enhances the detection efficiency.
Figure 3. The solid line represents the emission spectrum of the X-ray tube, while the red line represents the characteristic X-ray incident spectrum after monochromatization by LSDCC.
DCCs are categorized based on their curvature into semi-focusing (Johann), fully focusing (Johansson), and logarithmic spiral types. The semi-focusing type only partially meets the diffraction conditions, hence the characteristic X-ray incident spectrum monochromatized by the semi-focusing DCC is the least effective. The fully focusing type completely satisfies the diffraction conditions and achieves point-to-point focusing. However, the manufacturing process of fully focusing DCCs is extremely complex; in addition to bending, they must undergo a process of being ground into an R-curve surface. Natural crystals such as Si and Ge are brittle and very difficult to grind, and artificial crystals cannot be ground at all. Moreover, natural crystals typically diffract X-rays in a very narrow spectral region, resulting in only a portion of the target material's characteristic X-rays being diffracted and a low integral diffraction efficiency.
The GA-D240 utilizes a logarithmic spiral rotation double-concave artificial crystal, the DM30L, which is a patented product developed by the company's technical elite after two years of dedicated research. The logarithmic spiral DCC also fully satisfies the diffraction conditions. Although the focusing is not point-to-point but rather point-to-plane, this plane is quite small, typically around 2mm, so it can be considered as point-to-point. It uses DM artificial crystals, which have an integral diffraction efficiency 3 to 10 times higher than that of natural crystals. Additionally, it only requires bending without the need for grinding and splicing, making it easier to manufacture.
ASTM D2622 ASTM D7757 ASTM D6481 MEDXRF spectrometer Monochromatic Excitation Energy Dispersive X-ray Fluorescence Analyzer MEDXRF Light Element Spectrometer
High-Resolution (123eV) and High Count Rate (2 Mcps) Silicon Drift Detector (SDD)
There are various types of X-ray detectors, including proportional counters, Si-PIN detectors, and Silicon Drift Detectors (SDDs). The resolution of a detector is represented by the full width at half maximum (FWHM) of the characteristic peak. The net count of the characteristic peak is independent of the FWHM, but its background count is directly proportional to it. Therefore, the higher the resolution, the lower the detection limit. The FWHM of a proportional counter is about 8 times that of a semiconductor detector, so the detection limit is approximately √8 times higher. The resolution of Si-PIN is slightly worse than that of SDD, and its resolution drops sharply at high count rates, making SDD the best detector option.
The GA-D240 utilizes the VITUS H20 CUBE (top-grade) SDD detector produced by the German company KETEK. It has a resolution of less than 123eV, an effective detection area of 20mm², and a count rate of 2 Mcps.
Figure 5. Silicon Drift Detector (SDD)
Optimized kV, mA, and Target Material Combination for Micro-Focus Thin Beryllium Window X-ray Tube
The closer the X-ray energy used to excite the sample is to the absorption edge of the element required for analysis, the higher the excitation efficiency. The DM30L crystal only diffracts the high-intensity characteristic X-rays from the X-ray tube's emission spectrum, which are emitted by the target material. Therefore, the rational selection of target material can achieve the highest excitation efficiency. The standard model of GA-D240, capable of measuring elements below Cl, thus chooses Ag as the target material.
After selecting the target material, with the maximum power of the X-ray tube being constant, such as 50W, an optimized combination of tube voltage (kV) and current (mA) can achieve the maximum excitation efficiency. Since point-to-point focusing is used, a micro-focus X-ray tube must be employed. Due to the low characteristic X-ray energy of the target material, a thin beryllium window X-ray tube must be used.
The GA-D240 utilizes a 50W micro-focus thin beryllium window X-ray tube, with the standard model selecting Ag as the target and optimizing the combination of kV and mA.
Figure 6. Micro-Focus Thin Beryllium Window X-ray Tube
Calibration
Seven samples containing Si, P, S, Cl with known concentrations are used to calibrate the instrument, resulting in the working curve shown in Figure 7
Figure 7. Working Curve for Samples Containing Si, P, S, Cl
The correlation coefficients γ of these working curves are all greater than 0.999, indicating that the GA-D240 spectrometer has an extremely small linear error.
ASTM D2622 ASTM D7757 ASTM D6481 MEDXRF spectrometer Monochromatic Excitation Energy Dispersive X-ray Fluorescence Analyzer MEDXRF Light Element Spectrometer
Accuracy
To further test the accuracy of the analysis, five samples with varying sulfur content were prepared from diesel and light oil. Each sample was placed into two different sample cups for the sulfur accuracy test:
Table 2. Accuracy Results of Sulfur Analysis Determined by Five Unknown Samples
| Sample cup number |
Sample number one(ppm) |
Sample number two(ppm) |
Sample number three(ppm) |
| 1 |
1.15 |
5.31 |
10.32 |
| 2 |
1.08 |
4.92 |
9.89 |
| 3 |
0.90 |
5.05 |
10.11 |
| 4 |
0.93 |
4.78 |
9.67 |
| 5 |
1.01 |
4.88 |
9.51 |
| 6 |
1.03 |
5.16 |
9.90 |
| 7 |
0.97 |
5.26 |
9.81 |
| average value |
1.01 |
5.05 |
9.89 |
| standard deviation |
0.086 |
0.201 |
0.269 |
| RSD |
8.6% |
4.00% |
2.69% |
Table 2 displays the obtained concentration results (ppm) and their comparison with the nominal values. These results demonstrate that the GA-D240 spectrometer can achieve excellent accuracy for sulfur at low concentration levels.
Precision
Sulfur repeatability tests were conducted on three types of gasoline samples, with each type placed into seven different sample cups:
Table 1. Reproducibility Test Data for Sulfur Analysis of Gasoline Samples
| Sample cup number |
Sample number one(ppm) |
Sample number two(ppm) |
Sample number three(ppm) |
| 1 |
1.15 |
5.31 |
10.32 |
| 2 |
1.08 |
4.92 |
9.89 |
| 3 |
0.90 |
5.05 |
10.11 |
| 4 |
0.93 |
4.78 |
9.67 |
| 5 |
1.01 |
4.88 |
9.51 |
| 6 |
1.03 |
5.16 |
9.90 |
| 7 |
0.97 |
5.26 |
9.81 |
| average value |
1.01 |
5.05 |
9.89 |
| standard deviation |
0.086 |
0.201 |
0.269 |
| RSD |
8.6% |
4.00% |
2.69% |
These results indicate that at low concentration levels, excellent repeatability for sulfur can be achieved using the GA-D240 spectrometer.
Features
Rapid Simultaneous Analysis - Rapid analysis of required elements simultaneously, with content results generally given in tens of seconds.
Low Detection Limits - Utilizing advanced MEDXRF technology and LSDCC core technology, achieving the world's lowest detection limits with extremely high reproducibility and repeatability.
Long-term Stability - Equipped with a variable gain digital multichannel analyzer, featuring PHA automatic adjustment, drift correction, and deviation correction functions, ensuring excellent long-term stability.
Eco-friendly and Energy-saving - Radiation protection meets exemption requirements. Analysis does not contact or destroy samples, is pollution-free, does not require chemical reagents, nor does it require combustion.
Easy to Use - Operated by a touch screen. Samples are directly placed into the sample cups, and after being put into the instrument, simply press the [Start] button to truly achieve one-click operation.
High Reliability - Integrated design with high integration, strong environmental adaptability, strong anti-interference capability, and high reliability.
High Cost Performance - No need for steel cylinder gas, extremely low operating and maintenance costs. The price is half that of similar foreign products, making it a truly high cost-performance product.
Applicability
Suitable for refineries, testing and certification agencies, oil depots, and laboratories to measure a variety of oil products (such as gasoline, diesel, heavy oil, residual fuel oil, etc.), additives, additive-containing lubricating oils, and products in the refining process, with a measurement range from 0.5ppm to 10%.
Also suitable for the simultaneous measurement of elements below Cl in any material across various industries.
ASTM D2622 ASTM D7757 ASTM D6481 MEDXRF spectrometer Monochromatic Excitation Energy Dispersive X-ray Fluorescence Analyzer MEDXRF Light Element Spectrometer
Product Parameters
Main technical index
| Measurement Element |
Si, P, S, Cl (any element combination from B to Cl can be selected) |
| X-ray tube |
Voltage: ≤50keV
Current: ≤2mA
Power ≤50W
Target: Ag (Mo, Rh, Pd, Cr, etc., are optional) |
| Detector |
SDD, Effective Area: 20mm², Resolution: ≥123eV, Count Rate: ≤2Mcps, Incident Window: 8um Beryllium (AP3.3 is optional) |
| LOD(300s) |
Si: 1.2ppm, P: 0.7ppm, S: 0.26ppm, Cl: 0.14ppm (Standard type, 1 LSDCC crystal)
Si: 0.7ppm, P: 0.4ppm, S: 0.15ppm, Cl: 0.08ppm (Enhanced type, 3 LSDCC crystals) |
| Measuring range |
3 times the detection limit to 9.99% |
Linearity Error for Measuring
Linearity Error for Measuring |
Requirements for Measuring S:Meets GB/T11140, ISO20884, SH/T0842, ASTMD2622, D7039, D7220, etc.Measuring Si:Meets ASTMD7757, SH/T0706, SH/T0058, etc.Measuring Cl:eets ASTMD7536, ISO15597, etc.Measuring P:Meets ASTMD6481, SH/T0296, SH/T0631, etc. |
| System analysis time |
1~999s,Recommended value: 300s for micro measurement and 60s for major measurement |
| Operating Conditions |
Ambient Temperature: 5-40ºC, Relative Humidity: ≤85% (at 30ºC), Power Supply: 220V±20V, 50Hz, ≤200W |
| Measurement Atmosphere |
Self-inflating system or ammonia |
| Dimensions and Weight |
330mm x 460mm x 350mm, 25kg |
Note
If customers believe that the standard model of the GA-D240 does not meet their requirements, they may approach our company, and we will try our best to accommodate their needs. For instance, if a lower detection limit is required, our company can increase the number of crystals from one to three, thereby reducing the detection limit to 1/1.73 of the original. If there is a need to measure elements with atomic numbers below F, our company can select an SDD with an AP3.3 incident window for the customers. Should customers require the measurement of trace amounts of Al and Si on a high sulfur matrix, our company can replace the standard Ag target with a Mo target to meet the customer's requirements.
ASTM D2622 ASTM D7757 ASTM D6481 MEDXRF spectrometer Monochromatic Excitation Energy Dispersive X-ray Fluorescence Analyzer MEDXRF Light Element Spectrometer
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