An inductively coupled plasma-mass spectrometry (ICP-MS) device works by impacting ions on a dynode of an electron multiplier. The electron multiplier acts as a detector. When the ions impact the dynode, electrons are released and are amplified until a measurable pulse is produced. The ICP-MS software then relates the intensities of the measured pulses to those from standards, which make up the calibration curve, to determine the concentration of the element.
When using standards to generate the calibration curve, a reliable calibration curve is not always attained. What's the best way to generate these calibration curves so as to determine the concentrations of elemental metallic species, for instance?
Hi there
In ICP-MS a reliable calibration curve is not always obtained for many reasons but very unlikely because of the detector.
Most reasons for a bad calibration are isobaric and polyatomic interferences (in common quadrupole instruments)
The use of collision or reaction cells do limit those problems
Matrix effects can be reduced by matching your standards with the sample matrix.
The use of standard addition calibration curves and CRM for quality control almost ensure problem free analysis
I hope this helps
J. C. Tarafdar attached some files, It is best information in this please find and read details
ICP-MS is a sophisticated instrument. So you should have clear knowledge about the working system of this instrument.
1.Firstly, to generate a good calibration curve in ICP-MS, the sample passing route is need to clean from contamination. So you should need to clean from sample introduction system to sample passing route such as sampling cone, skimmer cone etc in regular basis. Otherwise, your curve will not be good. Also the DE-ionized water used for rinsing purpose must be changed everyday, otherwise it may affect your curve.
2. Secondly, you need to use internal standard with sample and standard . Otherwise, although your curve may be seem good without internal standard, but you would not confirm that, the curve is correct. In this case you will get a false result.
Recommended book/paper : AWWA , USEPA , Agilent website about ICP-MS etc.
Thank you.
In addition to the recommendations mentioned above (like use of internal standard, use of collision cell devices etc.) you should keep in mind that the intrinsic quality of ICP-MS analyses is the handling of extremely low concentrations. Due to these very low concentrations calibration series prepared in glassware vessels are heavily hampered on the one hand by adsorption by the glass walls. Cleaning thoroughly enhances adsorption by the glass surface; on the other hand without thorough cleaning glass is also useless in this case. Also, acidification of solutions (ICP-MS: 1 N HNO3) in this very low concentration range does not warrant absolute prevention of bias by adsorption to the glass walls. Even PTFE vessels showed bias effects when I had to analyze Barium in a concentration range up to 2 ppb (possibly due to material aging). However, preparation of calibration curves can be managed successfully by switching totally to the use of PFA vessels (perfluoroalkoxy copolymer). Therefore, labs using ICP-MS have generally to be equipped with a good stock of PFA material (without which the production of calibration curves is rather an adventure).
D. W. Zachmann
The glass-wares need for ICP-MS analysis must be ultra-clean. Otherwise, it may affect your calibration curve.
The chemicals need for ICP-MS analysis must be ultra-pure.
You can buy ultra-pure chemicals from Sigma-Aldrich or other renowned chemical company.
The acids need for analysis such as nitric acid, hydrochloric acid etc. must be ultra-pure. To purify acid, you can use sub-boiling distillation system.
The locally available ultra-pure acid is actually not ultra-pure in nature. It is not totally free from metal impurity. In this situation, you can remove metal impurity by using sub-boiling distillation system. Milestone's sells this system.
Recommended paper : Milestone website
Mashiur Rahman
- Badges
- Science method
- Similar topics
- Chemistry
- General Biochemistry
- Biochemical Techniques
- Analytical Chemistry