A Dumfries mum and daughter are using their shared love of chemistry to help keep NHS and care workers safe in the Covid-19 battle.Julie and Annabel MacGregor are working together to create a liquid form of Bitrex (denatonium benzoate) – the most bitter compound known to man – so that it can be sprayed to test PPE masks are fit for purpose.It is so bitter that anyone tasting it through a mask would immediately know the facial equipment could be penetrated by coronavirus.It is commonly used as a safety additive to stop children swallowing household, garden and car products.Julie, who is principal teacher for the science and technology faculty at St Joseph’s College, answered a call for chemistry teachers in the region to help Annan company