Depending of organic matter type, hot (80 deg C), 2.5N HCl for half an hour would do it. Filter and wash thoroughly; the source does not like Cl-.

If handling "sediments" (i.e., "old", resistant organic matter), there should be no problem. We have used that extensively for sulphates and carbonates in Palaeozoic black shales with good results.

Recent or modern organic matter, however, may be more labile, and I have no direct experience on that.

Good luck,


Hi all,
Can anyone suggest a protocol for removing (large amounts of) gypsum from sediments prior to d13C analysis of organic C?
Gabe Bowen
Gabriel J. Bowen
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