Disclosed are high concentration reagents for use in preparing DNA samples in low volume reactions. Such reagents include, for example, DNA end repair buffers for use in low volume DNA blunting and phosphorylating reactions, DNA adenylating buffers for use in a low volume DNA adenylating reaction, and DNA ligation buffers for use in low volume DNA adaptor ligation reactions with adaptors. Also disclosed are customized reagent plates and kits containing one or more of these low volume buffers for use in low volume DNA blunting, phosphorylating, adenylating, and ligation reactions. Methods of using the high concentration reagents (low volume buffers) and the customized reagent plates for preparing DNA sequencing libraries in low volume reactions are also disclosed.