Calibration Considerations Using Atomic Spectroscopy. “We’re not exactly rocket scientists”. And, luckily we don’t have to be. Why do we Calibrate? Direct vs. Indirect Methods. Direct Measurement Method: The Measurement of a Physical Property. Instruments rarely need to be calibrated.
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And, luckily we don’t have to be.
If you are reporting negative answers,
you could have a contamination problem!
How clean are your pipettes?
2% Nitric acid run through 5mL pipets and scanned on ICPMS
Total No. of Elements
Low Density PE-LDPE
High Density PE-HDPE
Si,B,NaImpurities in Container Materials
Every Standard needs a Container, but Be Careful
FEP (FLUORINATEDETHYLENEPROPYLENE)PFA (PERFLUOROALKOXY)FLEP (FLUORINATED HIGH-DENSITY POLYETHLYENE)PMP (POLYMETHYLPENTENE)PP (POLYPROPYLENE)HDPE (HIGH-DENSITY POLYETHYLENE)LDPE (LOW-DENSITY POLYETHYLENE)
Min. color retention time of KMnO4 mins
100/mlLaboratory Pure Water
ASTM Water Specifications
The Direct-Q ultrapure water system produces 18.2 Megohm-cm reagent water containing less than 30 ppb Total Organic Carbon directly from potable tap water. The system is ideal for scientists needing 5 to 15 L/day of ultrapure water for the preparation of culture media, buffers, blanks and standard solutions.
$203/500mlContaminates in Nitric Acid from Major Suppliers (ppb)
Check parts of the instrument that contact the sample.
Hg was not stable long enough to measure (minutes).Au was the next most unstable element, showing instability at the 2, 20, and 100 ppb levels at 3 days.
Pd showed instability only at the 2 and 10 ppb levels at 3 days.Pt and Ta showed instability only at the 2 and 10 ppb levels at 137 days.Ag showed instability only at the 10 and 100 ppb levels at 137 days.Mo, Sn, and Hf showed instability only at the 2 ppb level at 375 days.Ir showed instability only at the 2 ppb level at 300 days.All other elements showed no instability at 2-100 ppb for 375 days, including:Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Sc, Tb, Th, Tm, U, Yb, Y, Re, Rh, Ru, Te, Ge, Nb, Ti, W, Zr, Sb, As, Ba, Be, Bi, B, Cd, Ga, In, Pb, Se, Tl, V, Al, Ca, Cs, Cr+3, Co, Cu, Fe, Li, Mg, Mn, Ni, K, Rb, Na, Sr, and Zn.
Paul Gaines, Ph.D.Author of Reliable Measurements and other guides
5% relative Error from Certified Value
Detection Limits for Pb in Calcium Matrix
No analysis is complete until the final results have been correctly calculated and properly reported. The report should give the best values obtained and also indicate the probable accuracy or reliability of the results.
A single result can express the degree of uncertainty by the number of
MEAN (n=3) SD %RSD
27.6 ug/L 0.35ug/L 1.27%
MEAN (SD) Known QC % Recovery
19.3 (0.22) ug/L 20.0 ug/L 96.5%
%Recovery = 100 – (Known-Measured)/Known *100