The carbon isotopic composition of dissolved organic carbon (δ
13C
DOC) in speleothems, based on high-precision U-Th ages, has great potential to reconstruct past ecology, microbial activity, and carbon cycling. Identifying the reliability of the pretreatment and measurement of speleothem δ
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The carbon isotopic composition of dissolved organic carbon (δ
13C
DOC) in speleothems, based on high-precision U-Th ages, has great potential to reconstruct past ecology, microbial activity, and carbon cycling. Identifying the reliability of the pretreatment and measurement of speleothem δ
13C
DOC is therefore essential to putting it into practice. Actually, we have previously verified the reliability of the method for speleothem δ
13C
DOC measurements. However, it was only based on the final δ
13C
DOC values of homogeneous speleothem powder and is unable to evaluate the effects of different experimental conditions and the impacts of adding acid on δ
13C
DOC if using speleothem as the study samples. In this study, we used an organic reagent (potassium sorbate) as the study sample and designed a conditional experiment that simulates the protocols for speleothem δ
13C
DOC analysis and presented the resulting data to inspect the effects of the experimental processes on the analysis of δ
13C
DOC. The results show that the standard deviation of duplicate samples is 0.1‰, which is close to that of the previous work for organic reagents and water samples, and the results were not affected by different experimental conditions and operation steps (such as adding orthophosphoric acid, digestion time, and storage duration of resulting CO
2 in storage vessels), suggesting that this method is robust to detect the speleothem δ
13C
DOC. Considering the range and standard deviation of results, we proposed that the δ
13C
DOC record could be used in various studies when the amplitudes of the δ
13C
DOC record are larger than 0.1‰, especially greater than 0.4‰.
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