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Chapter 5
Sample preparation
5.1 Analysis of Prepared Samples
Analysis of bagged bulk samples
Sometimes it is convenient to measure samples in plastic bags. Without further
preparation of the sample, you can screen the site by testing each bag. Because you
are testing through a bag, test results will tend to be lower than test results obtained
from direct analysis. This effect will vary depending on the element analyzed and the
thickness of the plastic through which the sample is tested. Bagged samples can be
retested and/or be further prepared and then retested, allowing samples of particular
interest to be more accurately analyzed.
5.1.1 Sample Collection
Examine the site for differences in soil characteristics before sampling. Valid
results depend on a sufficient and appropriate selection of sites to sample. Incorrect
sample collection may give rise to misleading or meaningless results, regardless of the
analysis method. Delineate sections with different characteristics and treat them as
different areas. It may be desirable to subdivide larger areas even if they have the
same characteristics to ensure a thorough examination.
Make certain to label each bag thoroughly. Common information included on
each bag includes the person and/or the company who collected the sample, the
location and area where the sample was taken, and the date the sample was collected.
Prepared sample analysis is the most accurate method for determining the
concentration of elements in a bulk medium using the instrument. Sample preparation
will minimize the effects of moisture, large particle size, variations in particle size and
sample non-homogeneity.
Note: More sample preparation (drying, milling and sifting) will
yield greater accuracy. The drier, finer, and more
homogeneous the particles, the better the
measurements.
5.1.2 Preparing Bulk Soil Samples
TrueX recommends a specific sample protocol. Following this protocol for
preparing and testing samples is vital for achieving a level of accuracy comparable
with laboratory results.
The equipment you need to prepare samples. Among these are a mortar and pestle,
