Why Spark OES Requires Argon Gas?
Optical Emission Spectrometry (Spark OES), an important instrument for analyzing the composition of metal and alloy. Spark OES detected the percentage of elements in the ferrous and non-ferrous alloy, includes it's major metal matrix and other elements. The energy of spark burns the a thin surface of the metal sample, and generate the plasma. The excited atoms and ions in the plasma is detected by a spectrometer in the Spark OES instrument. Since each elements has it's characteristic peaks in certain wavelength(s) in the spectrum, one can analyze the composition of elements in the alloy, as well as their percentage. By the percentage of elements been detected, the grade of alloy is defined. Some Spark OES even designed PMT illuminate source for specific and increase its accuracy of specific elements. Such as GNR's S9 Atlantis Spark OES, the top level Spark OES.
The Reasons of Using Argon Gas
- Below are the reasons of using high purity argon as the shielding :
- Argon is an inert gas and won’t react with the elements in the alloy during the sparking period.
- Isolate the atmosphere by flushing the surface so that the spectrometer won’t detect the elements in the atmosphere.
- Spectrometer can detect the element, which has its characteristic peak below the wavelength 200nm correctly.
- In the composition of alloy, the element Argon is not ignored.
- Price of Argon is relatively inexpensive, typically, the price of inter gases from cheapest one to most expensive one:
Argon <Helium < Neon < Krypton or Xenon
Common Usage of Three Inert Gases
Helium: ultra-low temperature cooling, vapor deposition, balloons of diving suits filling.
Neon: neon light or mercury lamp filling, plasma research, laser beam (He-Ne)
Argon: metal welding, OES spectrometer.
Why Not Using Inexpensive Nitrogen?
Some alloy are composed of nitrogen and it is needed to be analyzed. And nitrogen can react with metals in under high temperature, and result residues. (e.g. Magnesium Nitride.)
Is It The Same Principle of TIG Welding?
It is different. TIG welding uses argon as a shielding gas to oxidation on the welding point. Spark OES uses argon gas to isolate the elements in the atmosphere, which are also the composition of the alloy.
Why Are Some Spark OES Consumes More Argon Gas?
Since argon gas had been used as shielding gas on the discharge electrode, some Spark OES shares the argon to purge the optics chamber in the spectrometer. It will also consume the argon gas. However, some special designed Spark OES can largely reduce the consumption of argon gas to the minimum, such as GNR's Spark OES.
The Stronger Argon Gas Flushing, The Better Result?
Not really. Too strong flushing will generate air entrainment result. The strength of GNR Spark OES had been optimized to the best air pressure while manufacturing.
What is Spark OES?
Spark OES is Optical Emission Spectroscopy. It is a technology based on optical emission spectroscopy. By a high-energy spark to be discharged on the metal surface and burn it, the plasma is generated. By detecting the plasma, and analyzing the spectrum of metal or alloy, one can determine the composition in the specific metal. Since there is only a few micrograms of metal is burned from the sample, Spark OES is a non-destructive analytical methods, and widely used in
ACTTR Technology presents GNR's advanced spectrometer product. G.N.R. srl is the few of Spark OES suppliers, who is still develope the most advanced Spark OES instrument in the world, and keep improving the technology. The most advanced design provide the users the best and most user-friendly Spark OES.
What's The Environment Needed For AAS Setup?
The laboratory for AA-7020 atomic absorption spectrometer needs at least the area of 12m2, there the sun light can not approach to the instrument. The water supply system and water drainage system is needed. In addition to the air conditioner, no any other heat sources. No dust, the walls and roofs preferably painted, and avoid the crumbs or dust from it. No large power supply facility, nor strong vibration machinery near by the laboratory.
What Are The Gases Needed in An AAS?
Flame Atomic Absorption Spectrometer (F-AAS)
The gas needed includes fuel and oxidant. The fuel is acetylene, and the oxidant can be compressed air or nitrous oxide. And the combination will be "acetylene + air" or "acetylene + nitrous oxide", to ignite the flame.
Specifications of gases needed are shown in the following table:
|
Gas required |
[Fuel] |
[Oxidant] |
[Oxidant] |
|
Purity |
99.9% |
O2, 21%; N2 78%; Ar 0.9%; CO2 300ppm; CH4 < 5ppm |
99.5% |
|
Minimum Pressure |
55 kPa (8 psi) |
330 kPa (47 psi) |
330 kPa (47 psi) |
|
Maximum Pressure |
96 kPa (14 psi) |
370 kPa (53 psi) |
370 kPa (53 psi) |
|
Minimum Flow Rate |
12 L/min |
24 L/min |
24 L/min |
Graphite Furnace Atomic Absorption Spectrometer (GF-AAS)
There are two kinds of gas are required by GF-AAS, the inert gas and auxiliary gas. Inert gas can be high-purity, oxygen-free nitrogen; or a high-purity, oxygen-free argon. The pressure have to be controlled in the range of 70-200kPa (10-30 psi). Insufficient pressure will affect the operation of the instrument. General use of the gas flow rate has to be about 3L / min (approximately 4–5 units on the flow meter).
Further, if there is a PAL auto sampler installed, the inert gas is also needed to be used in the pressurizing. Lacking of the inert gas, will prevent furnace operation.
Auxiliary gas is a second inert gas, the difference is that the gas is used to assist poured into a graphite furnace. General recommendations of using the auxiliary gas, in longer drying process, the cheaper nitrogen is recommended. In the ashing process, argon provides a better response. It's better to use argon.
Specifications of gases listed in the following table:
|
Gas required |
Nitrogen (high-purity O.F.N.) |
Argon (high purity grade) |
|
Purity |
Nitrogen 99.99% |
Argon 99.99% |
|
Gas Composition Recommendation |
Oxygen <10 ppm Methane <5ppm Carbon dioxide 0.1ppm Moisture at 15 °C <12ppm |
Oxygen <10 ppm Nitrogen <50ppm Carbon dioxide <5ppm Carbon monoxide <1ppm Hydrocarbons as CH <1ppm Hydrogen <1ppm Moisture at 15°C <12ppm |
|
Minimum Pressure |
70 kPa (10 psi) |
70 kPa (10 psi) |
|
Maximum Pressure |
200 kPa (30 psi) |
200 kPa (30 psi) |
|
Flow Rate |
3 L/min |
3 L/min |
Which Things to Know in Buying an AAS?
If you intended to comply with the relevant regulations, and to purchase a flame type atomic absorption spectrometer, it would be better to refer to the standard, "NIEA M111.01C", which is issued by NIEA Taiwan, and follow up the suggestions in the document.
The equipment you need for a complete include: FAAS, burner head, hollow cathode lamp, graphic display & recorder, pipette or micro-pipette, valves, analytical balance.
ACTTR Technology recommends a good combination, one-stop shopping for you. Not only allows you to meet the NIEA M111.01C specifications, as well as a good performance/price ratio, and you can own a flame with graphite furance combination type AAS, with auto switch function between FAAS and GFAAS in 2 seconds.
Atomic Absorption Spectrometer
AA-7020 standard version, a single-beam atomic absorption spectrometer (short optical path design, even for arsenic, selenium, also has a very low detection limit), with elements of light + deuterium lamp (for background removal), dual frequency light sources.
In the AA-7020 optical system design, not only with adjustable slit and photomultiplier tube, which can detect the wavelength range, but also a wider range of wavelength, than the normal, 190-900 nm.
AA-7020 has been configured with both flame and graphite furnace space inside the body in the mechanical design. Fully equipped complete functions of AAS at once, and you do not have to worry about the future requirment and purchase and set up the equipment again. Both the furnaces can be switched within two seconds, manually or automatically, calibration unnecessary, after switching, the experiments can be carried out immediately.
With AS-600 common type autosampler (for both flame & graphite furnace), executes the automatic wavelength selection, automatic changing slit, automatic switching element lamp, automatic switch on/off deuterium lamp, automatically switches atomizer, after necessary parameters are set up for each sample. Reach objective analysis of various elements automatically, far more than the definitions in NIEA M111.01C.
Burner Head
AA-7020 burner head and the spray chamber, the entire furnace are made by titanium metal. It is casting, durable, with long life. The burner monitoring function, can avoid wrong burner type is used while the nitrous oxide is applied.
Hollow Cathode Lamps
AA-7020 can be installed with six hollow cathode tubes, switch it, once only a sample of a single element lamp exposure after atomized.
Graphic Display and Recorder
AA-7020 free PC application software, powerful, not only with graphical display and a detailed record function - records the offset, atomic incompletion, leakage carbonization process, sensitivity, peak signal and so on. Also designed for exclusive features designed QC quality control, the whole sample group records can be stored by the parameters of standard deviation (SD), the relative standard deviation (RSD), the correlation coefficient, baseline drift, sensitivity correction, the sample cap, and more.
Pipette or Micro-pipette
We have all kinds of pipette (quantitative straw) or micro pipette (micropipette) with various capacities pipette tip available for purchasing.
Valve
We can set up the double meter gas valve for you, while the AAS is installed. Depending on your purchase order & experimental requirements, we can configure brass or stainless steel valve for you.
Analytical Balances
ACTTR Technology has a variety of analytical balance, satisfied with the definition of 0.1mg weighting accuracy in NIEA M111.01C.
ACTTR Technology also provides the related service of laboratory planning, equipment installation, on-site performance testing, after-sales maintenance, accessories, supplies, spare parts and other services, please contact to us for more information.