--- a/validate_affy_metadata.py	Thu Feb 14 13:28:26 2019 -0500
+++ b/validate_affy_metadata.py	Fri Feb 15 08:57:22 2019 -0500
@@ -76,7 +76,7 @@
             accumulated_msgs = add_error_msg(accumulated_msgs, "The input file contains more than 97 lines (must be 1 header line and no more than 96 data lines).")
             stop_error(accumulated_msgs)
         items = line.split("\t")
-        if len(items) != 30:
+        if len(items) != 32:
             accumulated_msgs = add_error_msg(accumulated_msgs, "Line %d contains %s columns, (must be 30)." % (i, len(items)))
             stop_error(accumulated_msgs)
         # Required and validated.
@@ -161,6 +161,14 @@
         # Required and validated.
         healing_time = items[29]
         accumulated_msgs = validate_decimal(i, healing_time, accumulated_msgs)
+        # Optional.
+        dna_extraction_method = items[9]
+        # Optional.
+        dna_concentration = items[31]
+        # If dna_concentration has a value, then it must be decimal.
+        if len(dna_concentration) > 0:
+            accumulated_msgs = validate_decimal(i, dna_concentration, accumulated_msgs)
+       
 
 if len(accumulated_msgs) > 0:
     stop_error(accumulated_msgs)