GC–MS ANALYSIS OF LIPIDS IN PREHISTORIC ROCK PAINTS AND ASSOCIATED OXALATE COATINGS FROM THE LOWER PECOS REGION, TEXAS*

Authors


† Corresponding author. Current address: Rhodes College, 2000 North Parkway, Memphis, Tennessee 38112, USA (russj@rhodes.edu).

Abstract

The presumption that lipids were used as binders/vehicles in pictograph paints from southwestern Texas was tested using gas chromatography–mass spectrometry (GC–MS). A one-step transesterification/derivatization procedure was used to convert bound and unbound fatty acids to fatty acid methyl esters for the analysis. Approximately 30 organic compounds were detected in the natural rock coating that encapsulates the paints, but there were no compounds unique to the paints. Moreover, the C16:0 and C18:0 concentrations in the paint samples were similar to the concentrations of these fatty acids in the rock coating, indicating that the compounds are native to the patina. Thus, lipid binders were either not used in the original paint mixture or have since degraded.

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