Basic Training 4th Annual ICP Conference

15.15 ICP-OES Measurement

Concerns with measurement: The technique of ‘Standard Additions’

• The technique of standard addi5ons is a tedious but more reliable approach for matrix correc5on. • For unknown matrices it may well be the fastest approach. • When using standard addi5ons on unknown matrices, it is possible to have severe spectral and background correc5on problems. It is cau5oned here that at least two spectral lines should be used and the spectral region carefully scanned and studied. • AEempt to make the addi5ons approximately 2x and 3x, where x is the analyte concentra5on.

16.1 ICP-MS Measurement

Resolu'on: Equal abundance Peaks are considered to be resolved if the magnitude of the valley between two adjacent peaks (h v ) is less than 10 % of the mean (h m ) of the magnitude of the peaks:

(h v

) < 0.1 (h m )

NOTE: This is for neighboring peaks of ~ the same intensity

ResoluIon (R) is defined as the mean mass (m M

) divided by the peak separaIon (Δm):

R = m M ÷ Δm Most commercial quadrupole mass spectrometers are capable of 0.8 amu mass resoluIon i.e R≈300 (at 10% of the valley definiIon and having equal adjacent peak intensiIes). ORen the resoluIon is said to be 0.8 amu indicaIng the mass difference that can be resolved at 10% valley definiIon. Here R ≈ 238 ÷ 0.8 = 297.5 ≈ 300