Recently we have had two customers worried about possible mold contamination in their vials. To keep the HDC alive they must be kept in a nutrient solution, which does provide a potential environment for fungal growth. The laboratory works under very strict conditions to ensure that opportunistic fungal contamination is almost impossible, and we are proud of the fact that virtually no vials actually arrive with any sort of contamination.

Upon investigation of our recent customer concerns, it has become apparent that some people have been informed that HDC are completely invisible to the naked eye, which is actually incorrect. The HDC are actually quite visible and observation of the HDC had been mistaken as the presence of mold.  We would like to thank Michael for supplying the below photo of a vial of 60 HDC, where the HDC can plainly be seen as small, white floating objects. THIS IS A NORMAL VIAL OF HDC! Often the HDC will sink to the bottom of the vial and clump together which you can sometimes see when you first receive your vials.  (The vial wall is thicker at the bottom which can make it more difficult to see the HDC.) If anyone sees similar white matter floating in their vials as shown in the photo, they should not be concerned. Mold growth looks quite different: there would be a single, much larger growth that looks similar to a clump of cotton wool which has been soaked in water.

We would like to reiterate that due to the precautions we take in vial preparation, mold growth is exceptionally rare. Of course, if  you ever have any concerns, never hesitate to contact the laboratory directly.