href links not validating properly

some of my links dont seem to validate, they are inserted using tinymce, i think it may be inserting the speech marks incorrectly ie:

“_blank” the first ” is sometimes seen as the wrong way round in the code…hope that makes sense (although they both look the same here)

<a title="a web site" href="https://www.awebsite.org.uk" target="_blank">www.awebsite.org.uk</a>