April 2008 Editor's Picks: Leistritz and Millrock Technology

Leistritz
Extruder processes small batches
The “Nano-16” twin-screw extruder from Leistritz (Somerville, NJ) incorporates a microplunger feeder that enables the unit to process 20–100-g batches. Charles Martin, general manager of Leistritz, explains that the microplunger feeder, a piston, uses positive displacement to feed small samples consistently at low rates. The extruder’s staging of unit operations and feeding are similar to those of a continuous process, Martin says. The machine runs continuously at rates ≤1000 g/h.

The device’s gearbox can drive 18- or 16-mm screws. Using a 16-mm screw produces an OD/ID ratio of 1.18 and a free volume of 0.9 cm3/diameter. The low free volume decreases the material’s residence time at low rates in the instrument, says Martin.

Unlike many small-volume extruders, the Nano-16 machine produces results that are scalable to production levels. The unit matches the shear rates of typical production-scale extruders, Martin says.

Millrock Technology
Freeze dryer is hydrogen-peroxide sterilizable
Millrock Technology’s (Kingston, NY) “Max” series freeze dryers feature an option that enable them to be sterilized with hydrogen peroxide. T.N. Thompson, president of Millrock, says that this validatable sterilization method is more cost effective than steam sterilization because it requires no additional equipment. In addition, hydrogen-peroxide sterilization achieves “the same log reduction in biological activity” as steam sterilization, says Thompson.

Unlike comparable products, the Max series freeze dryers feature programmable logic control. Thompson notes that many machines this size incorporate microprocessor control instead, which is more limited. The machines can be provided with 21 CFR Part 11 software to meet regulatory requirements.

The freeze dryers have about 20 ft² of shelf area and a maximum condensing capacity of 30 L. Biotechnology firms can perform sterile production runs with the Max series units, Thompson says.