What does ICP-MS stand for? Inductively Coupled Plasma Mass Spectrometry, or in my case it seemed to mean Intense, Complicated, Powerful, Maddening Science. Well, it definitely stands for the former…but it probably could be renamed as the latter for those who feel like they are a little overwhelmed. Today we had our first experience with the mass spectrometer….and what an experience it was!
What is a mass spectrometer you ask? Well, it is a machine that has the ability to detect low level concentrations of metals and some non-metals. In order to do this, the water sample is ionized (and turns into a mist) using an argon plasma (which glows green inside the machine). The ions are then separated depending on their mass and then quantified to show how much of each ion is present in the sample.
Much of the day was spent prepping and waiting for the mass spec to get up and running. First we organized our prepared vials and numbered them. Then we entered those numbers into the computer. Before we could put our samples into the mass spec, the machine needed to be tuned using a tuning solution (which contains a wide range of elements). As the tuning solution was being sampled, Audrey and I did what is called “tweaking the method”. As the readings of the tuning solution show up on the computer screen, they appear in graph format on the computer. Each element in the spectra has a specific mass, and in order to have accurate readings for the actual samples, the window that each element appears in needs to be shifted and narrowed. Once the method is complete, twenty samples followed by a water solution are run to ensure that everything is in running order. Finally, it is time to run your actual samples. The tray of vials is placed in the auto-sampler which is a clear box that has a sampling tube attached to the top. This is all automated, but it still needs to be watched over to ensure that all is going well. The sampling tube automatically sucks up some solution from each vial and goes through a wash cycle in between to ensure no contamination between samples. The data that the mass spec produces is then output to the computer indicating the counts per second for each present element indicating the concentrations of each element. Okay, don’t feel bad if you just glazed over that. I’m not sure if I fully understand it all still, and I’m the one who wrote it!
Crazy fact: Every six weeks WHOI goes through an amount of argon that costs $8,000! Now think of how expensive the machinery is! It’s a little daunting to be helping operate such equipment!