sample blocked the 0.45 um filter
I follow a sample preparation procedure from customer and want to filter 2ml liquid sample with 0.45um filter then I got totally jammed and couldn't get even one drop liquid out.
The filter I used was from Fisher scientific item# F2504-5. I also attached a photo of the filter I received.
My question is 1) is the filter I used correct? If not, any suggestion? 2) shall I pre-filter the sample with 1 micron filter paper?