ED-XRF

Energy Dispersive X-Ray Fluorescence (ED-XRF)

Make: Thermo Fishers; Model – ARL Quant’ X

Principle: A secondary fluorescence photon is emitted by the sample, under the bombardment of primary photons emitted by the X-ray tube. The secondary photon enters the detector. It is converted to an electrical impulse. The height of this pulse is directly proportional to the energy of the incoming photon.

Instrument Picture:

Accessories: Option to do analysis in vacuum and helium atmosphere.

Applications:

Typical uses of EDXRF include the analysis of

1. Aerosol particulate filters
2. RoHS / WEEE screening for toxins in plastics
3. Forensics and trace element analysis
4. Nutritional supplements
5. Magnetic media and semiconductors
6. Soil contamination and other environmental screening
7. Monitoring corrosion of cooling water
8. circuits Cement, feed and alternative fuels
9. Metallurgical slags and mining ores
10. Waste sludges and used oils
11. Thin films on filters
12. Gemstones, precious metals and jewelry

Instrument parameters:

Excitation:

X-ray Optics – 80^o geometry between X-ray tube, sample and detector, distance from sample to PCD – 28.5 mm, X-ray tube target 54.1 mm.

X-ray tube – End window Bremsstrahlung, Rh target, 50 watt, 76 micrometer Be window, air cooled.

X-ray generator – Voltage range, 4 to 50 kV in 1 kV increments. Current range, 0-1.98 mA in 0.02 mA increments, Maximum 50 Watt output

X-ray stability – 0.25 % RSD over any 8 hour period

Filters: Automated 8 position filter selection, Al, Cellulose, 2 Cu and 3 Pd filters

Filter Collimators: 1mm and 8.8 mm

Chamber: Automated control of air, Vaccum, helium

Detector: Si (Li) 15 mm² area, 155eV FWHM resolution for 5.9 keV X-ray at 1500 cps

Window: ≤ 7.6 mocron (0.3 mil) Beryllium (Be)

Cooling: Thermoelectric (Peltier ) and Air

Preamplifier: Electron resen

Performance

1. Elements determined: Sodium through Uranium

2. Concentration range: Parts per million to percent

3. Accuracy: Dependent on standards quality and concentration. Expected is 0.5 to 5.0 % relative

4. Precision: Dependent on concentration and analysis time. Expected is 0.5 to 5.0 %.

5. Calibration: Typically monthly

Samples Physical Properties:

Type: Solids, Powders, filtrates, liquids and thin films

Size: Standard single sample holds 1 ¼ inch (32 mm) dia sample cups or large, irregular samples up to the chamber size, i.e. 350 mm (W) x 450 (L) mm x 200 mm (H).

Calibration Curves:

Strengths:

1. Non destructive analysis

2.  Covers wide range from ppm to % level

3. It covers the periodic table from Na to U

4. Direct analysis of Solids and liquids.

Limitations:

1. Detection limits are poor for below ppm levels.

2. It won’t cover the light elements of periodic table.

3. To get homogeneous solid standards is difficult.