In this issue...

News from the Lab  Articles Online  Analytical Quick Tip  Joke of the Month  Stabilization of Mercury (Hg)

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Improved E-ordering
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Our Quick-Buy online ordering system has been improved. Order rundowns and e-mailed confirmations now include complete product descriptions and pricing.

New Standards
For use with EPA methods and QC analyses
We're offering two new standards for EPA Method 200.7 and updated standards for the new ILMO5.3 Method. See our new products for specific product details.

When working with Os, only mix the standard (which comes in HCl) with water and HCl. Do not use nitric acid. Nitric acid will slowly oxidize the Os to OsO₄, which is volatile (giving high results by ICP) and very toxic. The use of a dedicated waste container is also recommended.

With a growing interest in making Hg determinations using cold vapor atomic absorption (CVAA), ICP-MS and anodic stripping voltammetry (ASV), the stability of low-level Hg in samples as well as standards is receiving a lot of attention. Researchers at the National Exposure Research Laboratory, Exposure Dose Research Branch in Las Vegas (EDRB-LV), have found that adding AuCl₃ to the collected sample will preserve “all forms of mercury” in samples. They also reference NIST’s use of AuCl₃ for the successful preservation of trace Hg in SRM 1641B showing stability for ten years. These findings suggest that ppb levels of Hg in standards as well as samples can be preserved using the AuCl₃. An additional benefit is claimed to improve the stability of Ag. They also report that the addition of the AuCl₃ does not result in any interferences using CVAA, ASV, or ICP-MS.

The preservation matrix recommended is 2% HNO₃ + 1-ppm AuCl₃. Currently, most samples are preserved using just nitric acid. Inorganic Ventures’ laboratory has found that ppb Hg standards are stable in dilute HCl for periods greater than 1 year (this study is ongoing). The EDRB-LV findings are particularly encouraging for the ICP-MS operator who would like to analyze ppb to ppt Hg levels without using an HCl matrix, thereby avoiding or reducing the ⁴⁰Ar³⁵Cl interference upon ⁷⁵As.

Inorganic Ventures offers a 1000 µg/mL Gold as AuCl₃ in dilute HNO₃:  CGAUN1-1 (100 mL bottle) and CGAUN1-5 (500 ml bottle).

More Information:

»  Mercury Preservation Techniques (courtesy of EPA)
»  Mecury Stability Facts

Articles Online  more articles »

Compatibility and Precision Issues
Part six of our ICP Operations guide covers common compatibility issues that ICP operators face concerning the sample introduction system.

Linearity and Detection Limits
Part seven of our ICP Operations guide discusses key ICP performance characteristics including linear working ranges and detection limits.

Sample Size for Steel Analysis
Dr. Gaines provides tips for obtaining the best sample size for low-alloy steel analysis by ICP.

Determination of Hg in Sediment
Dr. Gaines offers a few tips for the determination of mercury and lanthanides in river sediment samples.

Joke of the Month  more humor »

Q: What did one titration say to the other?

A: "Let's meet at the endpoint."