Although Qiagen lists full biffer compositions for its anion exchange-based DNA purification kits (Midi, Maxi, etc), manual for minipreps do not mention buffer compositions and Qiagen technical support has long refused to disclose them.

Resuspension (P1) and Lysis (P2) are conventional alkaline lysis buffers listed in the Maxi prep manual:

P1: 50 mM Tris-HCl, pH 8.0, 10 mM EDTA, add RNAse A to 100 µg/ml.

P2: 200 mM NaOH, 1% SDS

The secret buffer compositions can be found in the US patent number 6383392:

N3 (Neutralization buffer): 4.2 M GuHCl, 0.9 M KAc, pH 4.8

PB (wash/binding buffer): 5.0 M GuHCl, 30% isopropanol

Note: the exact composition of the wash buffer PE is not given in the patent explicitely but hinted at in the Example 14: wash with 10 mM Tris, pH 7.5, 80% ethanol. Since PE is supplied as 5X concentrate to be diluted with pure ethanol, it implies that the concentrate is actually a 50 mM Tris. This isn't critical becase it is ethanol that plays essential role. I have substituted PE with just 70% ethanol in water for my minipreps and did not see any differences whatsoever..