In this issue:

News from the Lab  Articles Online  Analytical Quick Tip  IV Line Humor  Two Methods for CRM Certification

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NYAAEL & PaAAEL Exposition
Inorganic Ventures will be exhibiting at the 2008 NYAAEL & PaAAEL Exposition in Syracuse, New York. The exhibition will take place on the afternoon of July 21st. If you plan to attend, be sure to stop by our booth and pick up a set of lab coat pocket guards—a free (and useful) gift you won't find anywhere else!

New Utility for Distributors
We've developed a special utility to help official Inorganic Ventures distributors sell our products more effectively within their respective territories. Details will follow within the upcoming week. Our hope is that this tool will provide distributors with sales support for years to come.

Store all spectra on computer and collect the spectra for all lines of interest on each and every solution. This means that if you are interested in possibly using up to 6 lines for roughly 72 elements, then each solution spectrum totaling 72 x 6 = ~ 432 lines per solution and ~ 432 x 5 = 2160 spectra for each element need to be stored for future reference. Most ICP-MS applications would require far fewer data to be collected due to the reduced number of lines available and/or feasible.

According to ISO Guide 34:2000, a number of requirements exist for the certification of CRMs. The use of two independent methods is strongly suggested. The two methods should include one that is a 'primary' method. The second method can be secondary, but both methods must be validated, executed with a known QC standard, and compared using a statistical procedure that would determine if the means agree or disagree (independent method student T test).

In our case, agreement of the two methods is a requirement for release of the product. This agreement demonstrates the accuracy of the standard. The requirement of traceability to the International System of Units (SI) is where the use of one method (rather than the average of two) comes in for the purpose of reporting a certified value. The traceability requirement necessitates that the uncertainty be reported using ISO guidelines (Guide 35). The uncertainty calculation includes all sources of random and systematic error and must be 'provable' with an error budget and clear presentation of errors involved in the preparation of the CRM.

Consequently, a choice is left to the manufacturer as to which method to use for certification. It is common practice to use the method that has the lower uncertainty. The validity of this approach rests upon the accuracy of the uncertainty calculation, the inclusion of all possible sources of error, and a demonstration that the two methods used have Means that are statistically in agreement.

In short, there is no mathematical way of writing an equation that would make scientific sense from a traceability perspective based on an average of uncertainties.

Articles Online  more articles »

Sample Preparation Guide: Uranium and Thorium  · NEW ·
The ninth installment of our Sample Preparation Guide reviews detailed preparation tips for samples containing Thorium or Uranium.

Eliminating High and Erratic Blanks  · NEW ·
Dr. Gaines offers guidance to chemists using ICP-MS to help eliminate high and erratic blanks.

ICP Operations Guide  · COMPLETE ·
A clear 16-part online guide intended for anyone preparing samples and standards for measurement using ICP. Topics cover many day-to-day tasks required by all operators.

Reliable Measurements: A Guidebook for Trace Analysts  · COMPLETE ·
An essential 17-part online guide for chemical analysts. Topics cover all phases of sample collection, preparation, measurement, and data analysis.

Q: What do you do with a dead chemist?
A: Barium.

Submitted by Joan Darrow, Denver CO