Chase brand micro-hematocrit tubes are manufactured from soda lime glass, packed in plastic vials with reclosable snap-lock caps to maintain cleanliness. Ends may be sealed by flame, sealing clay or patented caps. They are available in borosilicate glass as a special order. Heparinized capillary tubes are treated to prevent blood clotting. Ammonium Heparin does not interfere with sodium identification.
