In this issue:

News from the Lab  Articles Online  Analytical Quick Tip  IV Line Humor  Chemical Compatibility of Multi-element Blends

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When working with chemical standards, determine if the standard is photosensitive and/or store in the dark if there is a concern. This is an issue with some of the precious metals and is a function of matrix. Photosensitivity will increase in the presence of higher energy light (sunlight as opposed to artificial light) and trace or minor amounts of organics especially if there is an extractable proton alpha to an electron withdrawing functional group such as a carbonyl group. The presence of chloride may increase instability to photo reduction. A classic example is Ag⁺ in HCl solutions.

It's important for multi-element blends to be compatible with the containers in which they are prepared and stored. It's equally important that they are compatible with the introduction system of the instrument(s) used to analyze the blend and with the other analytes within the blend. Some points to consider:

• Is the matrix of the standard compatible with glass or quartz? Glass is not compatible with HF and caustic matrices.
  
  
• Are there possible reactions between the chemical components of the standard that may adversely alter the standard with time? Photo-reduction of Ag in high HCl matrices, ppt of Ag in trace Cl matrices, ppt of Pb and Ba with trace levels of sulfate or chromate, ppt of the alkaline and rare earths with F^- in HF matrices, ppt of fluorinated elements like Sn(F)_x^-y in the presence of elements that would complex with the fluoride and therefore 'pull it away' from the metal stabilized as the fluoride complex, etc.
  
  
• Does the standard contain components that could form volatile compounds? A classic example is the oxidation of osmium chloride to the very volatile and toxic OsO₄ when nitric acid is added. Volatile compounds may not be lost from the standard solution but will give false high readings due to a disproportionate amount of the element making it to the plasma where the nebulization efficiency is greater due to the added mode of transport to the plasma as the vapor state.
  
  

Excerpt from 'ICP Quality Issues' -- read the full article here.

Articles Online  more articles »

Sample Preparation Guide: Calcium  · NEW ·
The fifth installment of our Sample Preparation Guide features detailed preparation tips for samples containing calcium (Ca).

Chemical Stability of Standards  · NEW ·
How long are average standard solutions chemically stable? Dr. Paul Gaines provides the answer.

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.

IV Line Humor  more humor »

"Old chemists never die, they just stop reacting."
—submitted by Richard Gouin, Trois-Rivières, QC