A SIMPLE MECHANICAL MIXER FOR SMALL VISCOUS LIPID-CONTAINING SAMPLES

The construction and performance characteristics of a simple device fo r rapid and convenient hydration and mixing of small volumes (10-500 m u l) of viscous hydrated lipid samples for use in X-ray diffraction/sc attering and other applications are described. The mixer has been used successfully over the past several years in studies of the equilibriu m properties of lipid mesophases and of the kinetics and mechanism of phase transitions. It is a low dead-volume (3.6-11.2 mu l) device that was built to facilitate maximal transfer of homogeneously hydrated li pid from the mixer into 1 mm diameter X-ray capillaries with minimal l oss of water during transfer and sample manipulation. The device consi sts of inexpensive, commercially available parts, the most important o f which are two microsyringes joined by a small-bore coupling needle. Also described in this report is a technique for determining the water content of the small volume, hydrated samples prepared with the mixer and an accessory for conveniently heating and/or degassing samples du ring mixing. Inadvertent sample healing that occurs during mixing is d escribed, (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.