Sampling Methodology
RACA-Med: Organic Residues Analyses
Sampling an Agora G 198 amphora in Pompeii
In order to process samples with GC-MS we need to have pottery powder.
To obtain this powder and avoid post-depositional contamination, when it is possible we take a fragment of the pottery and we sub-sample it in the laboratory (ideal situation). Before sampling in the field however we clean the surface of the pottery with a clean scalpel. The sample (fragment of the pottery is placed in alluminium foil and taken to the laboratory. Do not touch the alluminium foil nor the pottery with hands. Once in the laboratory, samples are mechanically cleaned with a Dremmel and pulverized in mortar.
If it is not possible to take a fragment of the pottery (usually due to the fact that amphorae are complete)we sample in the field (not recommended). In this case we take out all possible content of the amphora in the laboratory. After this, we clean very well the area that is going to be sampled as well as the area where it is possible that scraped powder could be in contact. We place alluminium foil in the best situation to collect all the powder obtained, and avoid the powder to be in tough with dirty surfaces. We use a clean scalpel (cleaned with acetone and chloroform) and we scrape the interior surface of the amphora until obtaining the needed quantity of powder (should be 3 gr at least).
A Dremmel drill can be used. However, it is very important to be careful that the powder will not get in contact with dirty surfaces. The point (diamante is usually adequate) has to be cleaned with acetone and chlorophorm before use. Whenever possible it is very important to take a control sample of the stratigraphic unit where the samples were recovered, to be able to check for post-depositional contamination.
In order to process samples with GC-MS we need to have pottery powder.
To obtain this powder and avoid post-depositional contamination, when it is possible we take a fragment of the pottery and we sub-sample it in the laboratory (ideal situation). Before sampling in the field however we clean the surface of the pottery with a clean scalpel. The sample (fragment of the pottery is placed in alluminium foil and taken to the laboratory. Do not touch the alluminium foil nor the pottery with hands. Once in the laboratory, samples are mechanically cleaned with a Dremmel and pulverized in mortar.
If it is not possible to take a fragment of the pottery (usually due to the fact that amphorae are complete)we sample in the field (not recommended). In this case we take out all possible content of the amphora in the laboratory. After this, we clean very well the area that is going to be sampled as well as the area where it is possible that scraped powder could be in contact. We place alluminium foil in the best situation to collect all the powder obtained, and avoid the powder to be in tough with dirty surfaces. We use a clean scalpel (cleaned with acetone and chloroform) and we scrape the interior surface of the amphora until obtaining the needed quantity of powder (should be 3 gr at least).
A Dremmel drill can be used. However, it is very important to be careful that the powder will not get in contact with dirty surfaces. The point (diamante is usually adequate) has to be cleaned with acetone and chlorophorm before use. Whenever possible it is very important to take a control sample of the stratigraphic unit where the samples were recovered, to be able to check for post-depositional contamination.