The Bio–Rad CHEF Mapper XA system incorporates patented FIGE and AFIGE* technologies for superior resolution in the range of 100 bp to 10 Mb, in addition to the features of the CHEF–DR II and the CHEF–DR III systems. The CHEF Mapper XA system also includes algorithms for deriving separation conditions. This system is ideal for both the PFGE novice and the seasoned expert. Each CHEF Mapper XA system is supplied with a power module, embedded auto–algorithm for protocol optimization, interactive algorithm program disk, electrophoresis cell, cooling module, variable–speed pump, and accessory kit. Automation The CHEF Mapper XA system offers two ways to optimize your separations. The unique auto–algorithm can automatically select optimal separation conditions, integrating 11 key variables and implementing starting separation conditions. Protocols can be refined using the Windows operating system–based interactive algorithm, which lets you specify several run variables simultaneously to derive optimal separation protocols. Customization Busy laboratories need equipment that can store and readily access key separation conditions. The CHEF Mapper XA system can store up to 99 programs. Application Versatility The CHEF Mapper XA system is the most flexible of the PFGE units. The CHEF Mapper XA system achieves higher resolution with greater speed and accuracy than any other PFGE system, making it ideal for all PFGE applications. The CHEF Mapper XA system lets you choose any pulse angle from 0 to 360°, which allows optimal separation of both chromosomal and plasmid DNA with one system. Accurate sizing of fragments requires an expanded linear range of separation. Switch–time ramps increase the mobility of fragments by gradually changing the switch times during the course of a run. Nonlinear (for example, concave or convex) ramps change the switch–time increments from the start to the end of a run. These nonlinear ramps separate fragments linearly from 50 to 700 kb, yielding more precise fragment size measurements. The multistate mode of the CHEF Mapper XA system enhances resolution in selected fragment size ranges. Each vector (angle of pulse) can be assigned its own voltage (field intensity) and its own switch time (duration of pulse). Up to eight different states can be combined into one run to optimize the separation of subsets of fragments in the sample. The application of secondary pulses of defined voltage, duration, angle, and frequency can enhance the separation and resolution of very large DNA molecules by releasing DNA caught in the gel matrix.