Why is an internal standard often used in quantitative analysis by ICP-MS?
Internal calibration is widely used in ICP-MS analyses mostly to compensate for physical interferences, to correct for variations in the instrument response as the analysis proceeds (signal drift), and to calculate the analyte concentrations of the samples.
Can ICP-MS quantify molecules?
Meanwhile, most elements of the periodic table including metals, metalloids, semimetals, non-metals, or halogens can be accurately determined by ICP-MS, allowing their application as surrogate standards for the quantification of all kinds of molecules whenever the stoichiometry of the used element tag is known.
How is ICP data calculated?
Multiply the concentration by the total extraction volume and the dilution factor, then divide by the sample weight = concentration in mg kg-1. Determine the MDL by multiplying the DL by the typical sample extraction volume and the dilution factor, then dividing by the typical sample weight = concentration in mg kg-1.
How do you choose internal standard concentration?
The proper internal standard should be chemically similar to the compound(s) that you are analyzing, but is not expected to be naturally present in your sample. It is best to choose compounds that have the same functional groups, boiling points, and activity as your target compounds.
How do you calculate concentration from internal standards?
A linear equation (y=mx + b) is obtained. Concentration of the analyte is calculated by solving for x when y is the ratio of analyte signal/internal standard signal in the unknown sample. Either one standard or several standards, to create a calibration curve, may be used.
How effective is internal standardization in ICP-OES analysis?
Recommendation (d) – The use of internal standardization is very effective in many cases but may introduce–or not correct for–all errors. This statement does not apply to isotope dilution ICP-MS that is considered to be a primary analytical technique. Matrix effects are arguably the subtlest danger to the ICP-OES analyst.
Do you trust calibration curves for ICP-MS?
In general I do not trust calibration curves. For ICP-MS, I do standard additions and I do not force 0 through 0, but rather I subtract the blank from the sample and sample + spike signals. However, there are different types of blanks:
What are the calibration options for ICP measurements?
Slight differences in the matrix can cause a considerable systematic error. The most common calibration technique options for ICP measurements are calibration curve and standard additions.
What is the output of an ICP-MS?
The output of an ICP-MS is numerical, and usually provided in counts per second. For any quantitative analysis, regardless of the technique, the instrument response is largely meaningless without reference to a known value.
