Lab 7- Schematic Diagram And Compenent Of Icp-ms

SCHEMATIC DIAGRAM AND COMPENENT OF ICP-MS:

Figure 1: Schematic of ICP-MS major components: sample introduction system, plasma torch, and mass spectrometer.

Figure 2: shown the schematic diagram of Inductively Coupled Plasma Mass Spectrometry Mass(ICPMS).

There are three(3) major compenent of ICP-MS which is sample introduction system, plasma torch and mass spectrometre. However, there is eight(8) of diffrent ICP-MS design available today that share many similiar compenent, which is nebulizer, spray chamber, plasma torch, interface cones, vacuum chamber, ion optics, mass analyzer, also detector. However, the

engineering design and implementation of these compenent can vary significantly from from one instrument to another. Below is the explanation for each compenent and its functions:

1) Nebulizers The most common design used for ICP-MS is the pneumatic nebulizer, which use mechanical forces of a gas flow (normally argon at a pressure of 20-30psi) to generate the sample aerosol. Some of the most popular design of pneumatic nebulizers include the concentric, microconcentric, microflow, and cross-flow. They are usually made from glass, but other nebulizer materials, such as various kinds of polymers, are becoming more popular. Particularly for highly corrosive samples and specialized applications. Nebulizer converts liquids into an aerosol, and that aerosol can then be swept into the plasma to create the ions. Once sample enters nebulizers, the liquid is then broken up into a fine aerosol by the pneumatic action of a flow of gas (~1L/min) “smashing” the liquid into tiny drop.

2) Spray chamber There are basically two design that are used which is double-pass and cyclonic spray chambers. The double pass is by far the most common, with the cyclonic type rapidly gaining in popularity. The function of spray chamber is to refect the larger aerosol droplets and also to smooth out nebulization pulses produced by

peristaltic pump, if it used. After that, some ICP-MS spray chambers are externally cooled for thermal stability of the sample and to reduce the amount of solvent going into the plasma.

3) Plasma torch Basic compenent to used to generate the source is a plasma tourch, radiofrequency(RF) coil, and power supply. The plasma tourch consist of three concentric tubes, which are normally made from quartz. The three tube is outer tube, middle tube and sample injector. The torch can be either one piece, in which all three tubes are connected, or it can employ a demountable design in which the tubes and the samples injector are separates. The sample injector is often made from other materials beside quartz, such as alumina, platinum, or sapphire. It highly corrosive material need to be analyzed. The most suitable gas to use

for all three flows is Argon. However, there are analytical benefits

to using other gas mixture, especially in nebulizer flow. The plasma used in an ICP-MS is made by partially ionizing argon gas (Ar → Ar+ + e−). The energy required for this reaction is obtained by pulsing an alternating electric current in wires that surround the argon gas

4) Interface cone-sampling ion. The role of the interface region, is to transport the ions efficiently, consistently, and with electrical integrity from the plasma. Which is at atmospheric pressure (760 torr), to the mass spectrometer analyzer region, which is at approximately 10-6 torr. This is the first achieve by directing the ions into the interface region. The interface consists of two or three metallic cones(depending on the design)

with very small orifices, which are maintained at a vacuum of ~1-2 torr with a mechanical roughing pump.

5) Vacuum chamber The distance from the interface to the detector of an ICP-MS is typically 1 meter or less. If an ion is to travel that distance, it cannot collide with any gas molecules. This requires removal of nearly all of the gas molecules in the space between the interface and the detector. This task is accomplished using a combination of a turbomolecular pump and mechanical roughing pump, which comprise the main components of the vacuum system. The turbomolecular pump works like a jet turbine and is capable of rapidly pumping a chamber to a pressure of 1 x 10-5 Torr,or less. The roughing (mechanical) pump backs the turbomolecular pump and evacuates the interface region.

6) Ions optics The ions optics, are positioned between the skimer cone (or cone) and the mass separation device. They typically consist of one or more electrostatically controlled lens compenents maintained at vacuum of approximately 10 -3 torr with a turbo molecular pump. They are not traditionally optics that we associate with ICP emission or atomic absorption, but are made up of a series of metallic plates, barrels or oin mirror. The function of the ion optics systems is to take ions from the hostile environment of the plasma at atmospheric pressure via the interface cones and steer them into the mass analyzer, which is under high vacuum.

7) Mass Spectrometer

The mass spectrometer separates the singly charged ions from each other by mass, serving as a mass filter. Three main types of mass spectrometers are used in commercial ICP-MS systems: quadrupole, time-of-flight, and magnetic sector. For overall performance and economic value, most laboratories choose an ICP-MS with a quadrupole mass spectrometer. A quadrupole works by setting voltages and radio frequencies to allow ions of a given mass-to-charge ratio to remain stable within the rods and pass through to the detector. Ions with different mass-to-charge ratios are unstable in the cell and are ejected. To cover the full mass range, the electronics rapidly change the conditions of the quadrupole to allow different mass-to-charge ratio ions to pass through.

8) Ion Detector. The ions exiting the mass spectrometer strike the active surface of the detector and generate a measurable electronic signal. The active surface of the detector, known as a dynode, releases an electron each time an ion strikes it. The ion exiting the quadrupole strikes the first dynode which releases electrons and starts the amplification process. The electrons released from the first dynode strike a second dynode where more electrons are released. This cascading of electrons continues until a measurable pulse is created. By counting the pulses generated by the detector, the system counts the ions that hit the first dynode. The detectors used in commercial instruments are capable of a wide dynamic range using a dual mode, which includes both digital and analog modes. Rapid data acquisition rates allow the ICP-MS to be used in the analysis of nano-particles, including the counting of individual nano-particle.

REFRENCE

Robert Thomas. 2013. Practical Guide to ICP-MS, A Tutorial as Beginners. 3rd ed. CRC Press Taylor

“The

Francis Group.

30-Minute

Guide

to

ICP-MS”

dlm.

https://www.perkinelmer.com/CMSResources/Images/44-74849tch_icpms thirtyminuteguide.pdf.

2004-2011