In this issue...

News from the Lab  Articles Online  Analytical Quick Tip  Joke of the Month  Sources of Uncertainty

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125  mL Custom Solutions
New bottle size for tailor-made standards!
Inorganic Ventures now offers 125mL custom blends for all ICP, ICP-MS, and Ion Chromatography applications. Now you can enjoy the same ultra-pure solutions in a more convenient size.

Dichloroacetate Standard
New CRM for EPA Method 300.1
Inorganic Ventures has designed a new 500µg/mL dichloroacetate standard for use with EPA Method 300.1. Available in 125mL and 500mL bottles.

Off the Mark - Humor
Science cartoons come to ivstandards.com
Select science-related Off the Mark cartoons (by Mark Parisi) are now featured in IV's Chemist's Corner. A new cartoon will appear every other month. Enjoy the lighter side of chemistry for a change!

Segregate your volumetric flasks, graduated cylinders, and glass pipettes into those dedicated to measuring HNO₃ and those dedicated to measuring HCl. Trace HCl in your sample may cause unexpected problems (precipitate Ag⁺ and Hg₂⁺², interfere with ⁷⁵As as ⁴⁰Ar³⁵Cl, etc.).

In the following example, the standard deviations are calculated from the % Relative Errors for each measurement. We have identified the sources of error for each of our test methods and have incorporated the calculations for the uncertainty of each measurement into a spreadsheet that has been written for each test method type (i.e. - there are many gravimetric procedures, but only one spreadsheet is needed).

In figure 1 below, the Error, % is termed in our procedures as the Relative Error and is not converted to % units. For example, if you weigh a 0.1 gram weight on a four-place balance, the Relative Error is 0.0001 / 0.1 = 0.001. However the Error, % is 0.1 (i.e. - the Relative Error multiplied by 100).

Figure 1 - Calculations and Results:

The Relative Errors are calculated by the analyst and entered in the database worksheet. The worksheet then multiplies the Relative Error by the Mean to get the error in absolute terms such as µg/mL. The Random Error of measurement is then added to this error using the square root of the sum of the squares of all the Relative Errors identified in the worksheet. The final uncertainty is calculated by multiplying this value by 2 and dividing by the square root of the number of measurements.

The above passage was taken from Understanding Error Budgets. Read the full article here.

Articles Online  more articles

Elemental and Matrix Compatibility
Part 1 of our all-new ICP Operations guide covers the basics of elemental matrix compatibility. Nitric acid, sulfuric acid, hydrofluoric acid, hydrochloric acid, and other common matrices are discussed.

Ashing Technique for Metals
Dr. Gaines recommends an ashing technique to determine the presence of seven metals in solid raw material samples.

Coal Sample Digestions
Dr. Gaines suggests his preferred method to digest coal samples for the analysis of various elements.

Joke of the Month  more humor

Q:  What did the Mass Spectrometer say to the Gas Chromatograph?

A:  Breaking up is hard to do.