diff --git a/internal-dev/obi-ext.owl b/internal-dev/obi-ext.owl
index 2b0fca47..b2ce413f 100644
--- a/internal-dev/obi-ext.owl
+++ b/internal-dev/obi-ext.owl
@@ -431,6 +431,12 @@
     <owl:Class rdf:about="http://purl.enanomapper.org/onto/ENM_8000279">
         <rdfs:subClassOf rdf:resource="http://purl.obolibrary.org/obo/OBI_0000070"/>
         <rdfs:label xml:lang="en">NP crossing ICP-OES</rdfs:label>
+	<rdfs:subClassOf>
+            <owl:Restriction>
+                <owl:onProperty rdf:resource="http://www.bioassayontology.org/bao#BAO_0000208"/>
+                <owl:someValuesFrom rdf:resource="http://purl.enanomapper.net/onto/ENM_8553741"/>
+            </owl:Restriction>
+        </rdfs:subClassOf>
     </owl:Class>