While ultracentrifuge technology has existed since the early 1900s, the past fifty years have seen a dramatic increase in the utility of analytical and preparative ultracentrifugation within the laboratory setting. The California-based company Beckman has established firm leadership in ultracentrifugation after its initial acquisition of Spinco’s (Specialized Instruments Corp.) vacuum ultracentrifuge product-line in the 1950s. Since then, ultracentrifuges have undergone significant improvements, some of which have been incorporated into the new Optima L-XP series from Beckman Coulter.
The Optima L-XP is a vacuum ultracentrifuge with a dynamic temperature regulation system and a footprint of approximately 4’x2’, and rises approximately 3’ off the ground, a convenient operating height for most users due to a shallow recess that holds the sample rotor. The Optima package can include several different rotor types ranging from fixed-angle, near-vertical angle, to swinging-bucket rotors. Each family of rotors has multiple models for a varying range of volumes, averaging at approximately 40 mL. The unit is delivered with the rotors separately packaged in cardboard, and the assembly process is straightforward and easy.
Operation of the Optima L-XP is convenient and controlled through a 7” graphical touch screen interface which allows the operator to select RPM settings up to 80,000 RPM, temperatures between 0°C and 40°C, time settings, and even acceleration and deceleration rates for the ultracentrifuge. After the sample tubes are carefully balanced and loaded, they can be transferred directly to the proprietary metal rotor- it is even possible to spin the sample tubes without tube caps in the appropriate rotors. This is a convenient option since the sample tubes fit tightly within the rotor wells when the caps are used; this makes extracting the tubes without a special “cap key” very difficult. Without the tube caps in place, it becomes possible to grip the exposed threading on the neck of the bottle. Importantly, the Optima L-XP is equipped with a rotor safety function- “Dynamic Rotor Inertia Check” (DRIC), which can sense imbalances in the rotor that may lead to catastrophic failure and equipment damage before the ultracentrifuge is allowed to run at critical revolutions per minute.
The Optima L-XP is marketed with an accessory set which includes a variety of sample tubes designed to fit the rotors. While samples can be loaded into the tubes with some care, it is entirely possible that the tube and the rotor wells themselves will accumulate sample matter. In the case of the Optima L-XP, the rotors and tubes are relatively easy to maintain and clean compared to other similar equipment. Over the course of a year, the operating lever on the sealing chamber door has broken, making it impossible to fully close and secure the chamber for operation. The latch lever was replaced quickly by Beckman Coulter- however, expect the door lever to be stressed with use due to its position on the significantly robust door, which can only be shut and opened by manipulating the lever control.
We use the Optima L-XP for protein isolation procedures in protein biology due to the fact that its automatic temperature regulation feature can delay undesirable protease activity and denaturation, and its fully programmable and automated operation can make previously difficult processes much simpler. The measured acceleration and deceleration functions of the L-XP have resulted in consistent and clean separation of sediments and liquid media from homogenized samples, pelleting suspended matter for isolation of supernatant or pellet in protein isolation procedures.
In short, the Beckman Coulter Optima L-XP is a thoughtfully designed vacuum ultracentrifuge for investigators looking for the top of the line in ultracentrifugation.