![]() ![]() Flame microsampling is accomplished using a micropipet to place 50–250 μL of sample in a Teflon funnel connected to the nebulizer, or by dipping the nebulizer tubing into the sample for a short time. For example, continuously aspirating a sample that has a high concentration of dissolved solids-sea water, for example, comes to mind-may build-up a solid de- posit on the burner head that obstructs the flame and that lowers the absorbance. Note that some of the elements have complex spectra. Set the monochromator EXACTLY to the wavelength peak approaching from the low wavelength side. Ensure that the hollow cathode lamp is operating correctly at the recommended lamp current. 4.9.2 Antimony - In the presence of lead (1,000 mg/L), a spectral interference may occur at the 217.6-nm resonance line. ![]() Use of an ionization suppressor (1,000 µg/mL of K as KCl) as described in Sec. 1.5/37mm Hollow Cathode Lamps are available in a variety of elements. 4.9.1 Aluminum - Aluminum may be as much as 15 ionized in a nitrous-oxide/acetylene flame. Continuous aspiration is sample intensive, typically requiring from 2–5 mL of sample.įlame microsampling allows us to introduce a discrete sample of fixed volume, and is useful if we have a limited amount of sample or when the sample’s matrix is incompatible with the flame atomizer. path before attempting to align the hollow cathode lamp and adjust the monochromator. Varian-Type Hollow Cathode Lamp ( 37mm or 1.5 Base). Both the UV glass and borosilicate windows can be fused. glass for wavelengths between 240 to 400nm, and high quality quartz for shorter wavelengths. ![]() The most common means for introducing a sample into a flame atomizer is a continuous aspiration in which the sample flows through the burner while we monitor absorbance. Other cup materials such as nickel, aluminium and brass may. The relative size of each zone depends on many factors, including the choice of fuel and oxidant, and their relative proportions. Single Element Lamp 1.5 (37mm) Diameter 2 Pin Socket Wavelength: 309.3nm Maximum Current: 15mA Fits in Varian, Analytic Jena, GBC, Shimadzu, Thermo Unicam. Profile of typical flame using a slot burner. The diagram show below is the picture of Hollow cathode lamp. The tube is sealed and neon and argon are filled at a pressure of 1 to 5 torr.ġ5. So, these lamps give highly specific radiation. The use of other methods like monochromators gives radiation with a bandwidth of 1nm. At what pressure should the gases in the sealed tube be maintained in the Hollow cathode lamp?Įxplanation: It consists of a cylindrical cathode and an anode made of tungsten. The advantage of a Hollow cathode lamp is that it provides radiation with a bandwidth of 0.001 to 0.01nm. Positive ions collide with negatively charged cathode surface and metal atoms from cathode are ejected.ġ4. ![]() Which of the following options explains the process of ‘sputtering’ that occurs in Hollow Cathode Lamp?Ī) Positive ions collide with cathode surface and metal atoms from cathode are ejectedī) Negative ions collide with cathode surface and metal atoms from anode are ejectedĬ) Positive ions collide with negative ions and metal atoms from anode are ejectedĭ) Positive ions collide with negative ions and photons are ejectedĮxplanation: When potential is applied across the electrode, the gas filled in tube ionises and flow of current occurs. Which of the following is the function of the chopper in Atomic Absorption Spectroscopy?ī) To break the steady light into pulsating lightĭ) To reduce the sample into atomic stateġ3. The protective shield can be made of glass too.ĥ. How can the intensity of radiation be increased in Hollow cathode lamp?Ī) Addition of non-conductive protective shield of micaī) Addition of nitrogen to neon or argon in the lampĬ) Increasing the pressure of the filling gasĮxplanation: The intensity of radiation is increased in Hollow cathode lamp by the addition of non-conductive protective shield of mica. In Atomic Absorption Spectroscopy, with what material is the cathode in Hollow cathode lamp constructed?Įxplanation: The cathode in Hollow cathode lamp is constructed of the element to be investigated. ![]()
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