Modular Microcentrifuge Tube Ice Rack System by scocioba

Last crawled date: 3 years ago

Everyone in molecular biology uses an ice bucket to chill their samples during routine procedures like PCR. If your lab is well funded you might even have a fancy ice rack that sells for upwards of $80 and keeps your samples in stable contact with ice/water. For those on a shoe-string budget like myself, a cheap and simple alternative was needed. Enter the Modular Microcentrifuge Ice Rack System.
The system is very simple. All it requires is a print of the lid, water, and a styrofoam cup. I use a shallow Dart cup that came with some mexican take-out. It measures approx 4" wide at the mouth, 2" tall, and tapers to a base of about 3". This lid holds 9 1.5mL microcentrifuge tubes but I will be making more lids that cater to a wider range of tubes including the 50mL, 15mL, and even 0.2mL PCR tubes.
Now for the dorky part: Data!
After freezing about 250mL of tap water in the system for 3 hours, I did a triple repeat of an experiment that measured the rate at which 1mL of distilled water cooled from room temp to a steady state. I used a VWR Multi-Thermometer that is NIST traceable for the measurements and wrote down the temp every minute for ten minutes. The thermometer was allowed to sit in the sample at room temperature for one minute prior to insertion into the system and taking the initial reading. I included a picture of the graphed data for your viewing pleasure.
The systems works great and cools to the required 2-6C in about 4 minutes and can hold the temperature for at least 1 hour. I would recommend a longer time in the freezer prior to use to ensure complete ice formation. The lid itself is designed to fit snugly onto the cup lip and may require a little wiggling to get it on. Any 4" mouthed cup will do. I designed the lid so that the tubes never make contact with the water so there is no condensation or chance of contamination due to water ingress. Enjoy!
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