You have contamination. This could be from your micropipettes, your water, buffer, etc. Throw away your reagents, clean your work area, don't use the same micropipettes for DNA and PCR products, and try again. I'd start with just one primer pair and see if you can solve the contamination issue before using all 15 primer sets. Good luck!

It is unclear to me because there is no size standard. I find it hard to believe that 15 different sets of primers are all contaminated unless you have used them all before and been very careless so I am wondering if you have a serious primer dimer problem often caused by poor primer design, using too much primer and leaving the reaction mix for too long before starting cycling. Try a primer set with dilutions of primer to 1/50th of your current amount on a sample that has worked before and preferably using a hot start enzyme if you can borrow some and see if the small bands that you have disappear. Also check your dilutions to get the working dilution of your primers

Thank you Paul Rutland and Katie A S Burnette !

Good catch Paul Rutland . I didn't notice that there wasn't a size standard for comparison. The bands look either over-exposed or very bright (hard to tell). Those very well could be primer dimers. Paula Suarez-Henriques What size products were you expecting?

Hi Paula Suarez-Henriques

What is your target size of your pcr product. If all blanks are amplified, there is every possibility of contamination or primer dimer problems. You better check your working protocols and careful about contamination.

Thanks

Hi

I think you have contamination rather than primer dimer. i would not expect primer dimer formation by the 15 different sets of primer.

Katie A S Burnette Md. Mahiuddin Zahangir Omar Elhenshir , hello and thanks again, my products size range from 75 to 99 nt. I did throw away all my reagents and cleaned the flow, sterilised everything that could be sterilised and started again.