Monday, 7 March 2011

Du-sty Du-sty Du Nuöy Ring

So I went to the lab today. I was just hanging around checked some emails. I as working on a paper when one of my colleagues stopped me. Since I was doing nothing at the time and I am a senior person in the lab I had no way of getting out of not helping with a problem. Even worse he wanted to use one of the tensiometers in our lab to measure the surface tension of his samples. Actually this was a tensiometer that was sitting in the back of the room on an expensive nonvibrating table. It had a fairly old computer but the whole system could not have been that old. It was an old Du Nuöy ring method with a platinum Du Nuöy ring encased in a cylindrical glass and plastic case. A thin layer of dust was on the top of the device.

I looked at this thing. This was the first time I saw it. This device was like that ugly lamp in the room that you inherited from your Aunt Hilda but nobody really turns it on or wants to use it. This device was not even plugged into the wall. My colleague and I set it up even managing to get rid of the dust off the device. We cleaned out the cup which had something dried on it. We then proceeded to turn on the computer. A log file opened and communicated with this Du Nuöy ring Tensiometer.

'So what do you want to measure?' He told me he had extracted and purified these oxidized phospholipids from cells that with lipid peroxidation. It had taken him a week to do the experiment. He wanted to measure the property of them using this Du Nuöy tensiometer. We filled the cup with 10 ml of water. We wanted to calibrate the thing. When we calibrated it was reading a value completely off from the value of the buffer of 72.8 dynes/cm.

So I took the ring out and looked at it. 'Just as I expected it is bent.' I called another colleague over who was senior to me and took out this kit for rebending the ring. Yeah the instrument has a freakin' kit that you need to rebend this fragile platinum ring. 'Why don't we just order a new one?' 'They are 800 euros my colleague replied.' After 40 minutes we managed to get a decent value for water.

My colleague then started to put his valuable lipids to try to get Critical Micelle Concentration ((CMC)the concentration where they are start to form micelles). The most accurate way is by measuring the surface tension. You can also measure the dynamic light scattering but we prefer this method in our lab. So he spreads in increments his precious lipids onto the water. And we start to measure. Add some more, measure. We have to waste a lot on this method because of the volume and it was taking forever. To get the CMC value with the ring you have waste a lot of lipids and you have to do it a number of times.

My boss was in the back of the room watching what we are doing. Sometimes he just watches to see if we are doing things correctly. It is science and sometimes you can do things by trial and error. However, he does want us to get our work done nicely and accurately. He kind of smiled like a father smiles when his son does not have the experience to do something the easy way but just likes to see them struggle at it to see if you can figure it out. Like the time I was struggling moving a huge couch when my father said it had wheels underneath. Often I do not figure it out.

So my boss came over. 'What are you doing?', he said in a slight Finnish accent. The explanation was fairly obvious but we explained it to him. 'Why don't you use the Delta-8?' The Delta-8 was an eight probed tensiometer that works with a slightly different technology, the Padday method. The Delta-8 sat on the opposite side of the room. It was sleek, easy to use and it was constantly being used someone in the lab. Neither me or my colleague had experience using it though. My colleague decided to use one that he heard about in some old journals from the 1970s. My boss showed us in about 10 minutes how to use it. The Delta-8 works with 96 well plates so you can vary the concentrations and you do not need to use that much lipids. Best of all it is self cleaning! We reproduced results 12 minutes after to find the CMC was 23 mM. A result that will go in the paper. I hate wasting time but sometimes science is time well wasted.