One of the great advantages of elemental analysis is the relatively small sample weights that are required for analysis. The sample weights used will vary according to the application, the sample type, detection limits and precision that needs to be achieved. Detection limits will normally be in the order of 0.01% or better but lower detection levels or precision can often be achieved by changing the analytical mode, increasing the sample weight and/or increasing the gain to achieve a better signal to noise ratio.
Please see below our weight guide to the sample sizes we require (per run) for each type of determination. Larger samples are preferred because our analysts must be able to recover sufficient sample from the vial to transfer into small capsules. It is very useful for us to have more sample to allow us to run random QC check samples. This also ensures that we can keep our sample turn-around on schedule should we have any problems with our instrumentation or encounter other unforeseen failures. We can return unused sample upon request.
Sample preparation might be required to obtain the best representation at the recommended weight levels. Unless otherwise requested samples are analysed ’as received’.
Samples must be free from residual solvents or moisture to provide reliable results. Depending upon the sample type, samples should dehydrated by freeze drying or vacuum oven drying to constant weight. Samples should be finely ground using a mortar & pestle or a ball mill to ensure that the sample is representative at the target sample weight.
If inorganic carbon is present it can be eliminated by direct acidification with dilute hydrochloric acid or indirectly by exposure to concentrated sulphurous acid vapour. Where samples are submitted for total organic carbon we will pre-treat your samples in this way to remove any inorganic carbon. Total inorganic carbon (TIC) is determined by difference from the total carbon and total organic carbon values.
We are able to prepare or pre-treat your samples at additional cost. We are able to accurately determine loss of weight on drying (on a micro scale) where required. Please contact us to discuss any aspects of sample preparation that you may require.
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