diff --git a/R/calc_vol.R b/R/calc_vol.R
index b9ad4f0..e8dea07 100644
--- a/R/calc_vol.R
+++ b/R/calc_vol.R
@@ -72,7 +72,8 @@ calc_vol <-
     if(from == "smiles") {
       compound_sdf_list <- lapply(input, ChemmineR::smiles2sdf)
     }
-    
+    #TODO use ChemmineR::validSDF() to check for any invalid inputs
+    # Warn and return NA for any that aren't valid??
     fx_groups_df_list <-
       lapply(compound_sdf_list, get_fx_groups)
     names(fx_groups_df_list) <- input