In this issue...

News from the Lab  Articles Online  Analytical Quick Tip  Joke of the Month  Developing a Sampling Plan

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When taking aliquots of standards for dilution and mixing, always weigh the aliquot and calculate the mL taken using the certified density of the standard. This precaution will save time in the long run.

In the development of a sampling procedure, the first step is to reexamine the problem definition. The analyst must review how the final results will be used and obtain an understanding of the characteristics of the sample population.

For example, the question "Has this industrial site been contaminated with Pb and Hg?" addresses the immediate concern and prompts the analyst to start thinking about other issues. This thought process would bring about additional questions, such as "Have Pb and Hg compounds been used on this site?" and "What type(s) of compounds were used?"and "Where were these compounds stored?". These questions lead the analyst to an assessment of the scope of the sample population. In some cases, the whole site would be sampled. At other times, the sampling would be limited to specific areas. The analyst can then recommend a sampling procedure using methods already published on soil sampling and tailored to answering the specific question. The analyst may determine that only 3-5 samples are needed in an area where drums that contained Pb and Hg compounds were placed. The other extreme would be to propose a random sampling over a 20 acre site, where 20 samples are pulled in a equally spaced geometric fashion. Other concerns pertain to the ‘normal' levels of Pb and Hg in the soil for that area where state and local environmental agencies would be contacted for baseline data.

By knowing the objective, the analyst is in a position to recommend sampling procedures that are designed to obtain a reliable answer.

The above passage was taken from the 'Sampling and Sub-sampling' section of our Reliable Measurements guide.

More Information:

» Determination of Sampling and Sub-Sampling Errors
» Contamination Issues During Sampling

Articles Online  more articles »

Spectral Interferences: Types, Avoidance, and Correction
Part eight of our ICP Operations guide covers spectral interference correction for ICP-OES and ICP-MS.

Key Instrument Parameters
Part nine of our ICP Operations guide discusses the key ICP and ICP-MS parameters that require adjustment on a regular basis.

Analyzing Cement
Dr. Gaines offers insights regarding analysis of the mineral composition of concrete.

As Line Interferences from Fe
Dr. Gaines offers his suggestions when dealing with interferences on the As emission lines caused by high levels of Fe.

Joke of the Month  more humor »

Titanium is the most amorous metal. When it gets hot, it'll combine with anything.