Improved technique for storage of tear microvolumes.

The authors have developed an improved technique for storage of fluid microvolumes prior to osmolality measurement. To date, tear samples have been stored in a column of Cargilles B immersion oil contained within a capillary tube, sealed at one end with Critoseal. Covering the open end of this tube with Parafilm now provides reliable storage of 0.5-microliter samples for up to 24 hr; using water-saturated Cargilles B immersion oil within the capillary tube, and covering the open end of the tube with Parafilm now provides reliable storage of 0.1-microliter samples for up to 18 hr.