What is the difference between AMPure XP and SPRIselect beads of Beckman?

[sheshet]

Beckman has two types of SPRi beads- AMPure and SPRIselect, the later are much more expensive. According to their data sheets Ampure XP is used for PCR product purification while SPRIselect is used for size selection. However I know that many people use AMPure XP for double sided size selection. Does somebody knows what is the difference between AMPure XP and SPRIselect?
Is it the beads coating (similar to difference between AMPure and AMPure XP) or may be the buffer components (PEG? NaCl, other crowding agent)?
Does anybody know for sure what are the bufferes composed of?
Thanks

[kerplunk412]

I called Beckman to ask them this exact question, and I was told by a scientist there that the only difference is that the SPRISelect are QC'ed for size selection use and AMPure XP are not. So the components should be the same, but the SPRISelect are the only beads that are tested to perform size selection as advertised.

I would recommend going with AMPure XP and testing them with a 100 bp ladder or similar DNA sample, such as a plasmid digest, to make sure they are performing as advertised. It is good practice to perform this test with each new batch of AMPure you purchase.

I would also like to mention that Beckman tech support was very friendly and quickly got me to a person who could answer my question knowledgeably, so kudos to them for customer service.

[sheshet]

Thank you very much. I suspected the beads are the same but when I asked the same question the Beckman tech support they replied that those are different beads, however they refused to specify what the difference is! You were lucky to speak with knowledgeable person.
Do you know by chance what is the composition of the buffer?

[cbird]

Actually, there seems to be a difference between the reagents used. The AMPure XP reagent is 20% PEG in 2.5M NaCl. I do not know what the SPRI solution is (perhaps a different concentration of PEG), but the KAPA Illumina prep kits come AMPure XP beads and SPRI solution (no beads) that is added to the beads. So, the question is, is the SPRI solution 20% PEG in 2.5M NaCl?