Plug for osmometry sample cup
A plug for an osmometry sample cup or vial is provided that seals the sample cup or vial to prevent significant evaporation of a sample solution in the cup or vial prior to obtaining an osmolality measurement.
1. A plug for an osmometry sample cup or vial, comprising:
a body extending longitudinally from a proximal end to a distal end, a passage extending longitudinally through an interior of the body from an opening at the proximal end to an opening at the distal end;
a diaphragm extending transversely across the passage in a distal region of the body, the diaphragm formed of a material penetrable by a tip of an osmometer temperature probe.
2. The plug of claim 1 , wherein the diaphragm has a thickness ranging from 0.005 to 0.025 inch.
3. The plug of claim 1 , wherein the diaphragm comprises an elastomeric material having a durometer hardness ranging from 40 to 80 Shore A or a thermoplastic material having a durometer hardness ranging from 45 to 75 Shore D.
4. The plug of claim 1 , wherein the diaphragm includes a weakened area.
5. The plug of claim 4 , wherein the weakened area of the diaphragm comprises one or more slits or holes.
6. The plug of claim 1 , further comprising a sealing element disposed circumferentially around an exterior surface of the longitudinal body at a proximal region of the longitudinal body.
7. The plug of claim 1 , further comprising a plurality of sealing elements disposed circumferentially around an exterior surface of the longitudinal body at a proximal region of the longitudinal body.
8. The plug of claim 1 , further comprising a plurality of guide ribs extending longitudinally along an exterior surface of the longitudinal body.
9. The plug of claim 8 , wherein the ribs are spaced symmetrically about the exterior of the longitudinal body.
10. The plug of claim 1 , further comprising a flange disposed about the proximal end of the body.
11. The plug of claim 1 , wherein the passage through the longitudinal body is tapered from the distal proximal opening to a mid-region of the longitudinal body.
12. The plug of claim 1 , wherein the body is formed of a thermoplastic elastomeric material or a silicone material.
13. The plug of claim 1 , wherein the plug is sized to accommodate an osmometer sample cup or vial having a sample volume ranging from 10 μL to 10 mL.
14. An osmometry sample cup assembly comprising:
an osmometry sample cup; and
the plug of claim 1 , wherein the plug is sized to fit within and seal the osmometer sample cup.
15. A method of performing an osmolality measurement on a sample solution, comprising:
placing a volume of the sample solution in a sample cup or vial;
sealing the sample cup or vial with the plug of claim 1 ;
penetrating the diaphragm in the plug with a temperature probe;
supercooling the sample;
initiating freezing of the sample; and
obtaining temperature measurements of the sample solution in the sample cup or vial.
16. The method of claim 15 , further comprising:
penetrating the diaphragm in the plug with the temperature probe after a time of greater than 1 minute.
17. The method of claim 15 , further comprising:
wiping the temperature probe clean as it is pulled out of the plug.
18. The method of claim 15 , wherein the sample solution is selected from the group consisting of blood, serum, plasma, urine, milk, and cell culture media.
19. The method of claim 15 , wherein the sample solution is an aqueous based solution.