Chemistry picture of the week: Filtering


In Australia, apart from the final talk of a PhD and obviously thesis submission, the most important event of one’s postgraduate degree is the first year confirmation. The confirmation occurs at the end of your first year, and is essentially a review of your work by your supervisor and a panel of other academics in the school. The academics’ job is to decide whether you’re suitable to be confirmed as a PhD candidate and to continue your research at the university. At the university I completed my undergraduate and honours, this was largely a formality — even the laziest of students always passed their confirmations and were allowed to continue. At the University of Melbourne, I have heard of students failing and having to resubmit. At the start of 2015, I saw two of my co-workers stressing out over their confirmations. Their nervousness was obvious — I even caught them practicing their talks in an isolated instrument room at the back of the lab. And this year, it’s my turn.

I’m a fairly fast writer once I get on a roll, so I’m not too concerned about the 30-odd pages we’re supposed to produce as the written report. I think if I leave that for the month of February, I’ll still have plenty of time — especially as I try to be organised with my data as I’ve talked about before. What I am currently concerned with is amassing as much hard data for my report as I can — so when I make a statement about my chemistry, I can refer to an experiment or measurement I’ve conducted to try to qualify or quantify that statement. As such, the last couple of weeks of December and the first weeks of 2016 have been largely spent avoiding attempts to synthesise new materials, instead repeating old reactions to yield plenty of material to conduct measurements and further experiments on. That means that my last month or so of work has consisted of a lot of filtering.

Most chemical reactions synthetic chemists perform are done in a solvent, which is a liquid such as water or ethanol that dissolves other chemicals. In many cases, the desired product is a solid, which means that you require a method to separate the solid from the remaining liquid. Enter filtering. Filtering may be familiar from filter coffee, which is made by passing boiling water through a filter paper holding coffee grounds. The end result is the extract of coffee without the solid coffee beans. Filtering works in the reverse: you start with a mixture of solid and liquid, and pass the mixture through a filter paper which catches the solid and deposits the liquid. To speed up the process, we use vacuum filtering, which pulls the liquid through much faster and also dries the remaining solid.

Here’s a secret, though: it’s deathly boring, particularly when you’re filtering tiny amounts and are trying to make sure you don’t lose any of your product. When it’s small crystals, you want to drop as much solid at a time onto the filter paper and always drop it on the same, small spot so that the solid can catch more solid. It’s a slow, painstaking process when you have vials and vials and vials to empty using this method. Afterward, I do get to look at my beautiful shiny crystals under the microscope to note the appearance of the bulk product, which does give a bit of satisfaction to the whole process. In the worst case scenario (which happens frustratingly often given how science tends to require a lot of trial and error), I end up wasting this little bit of product on an experiment that gives me no useful results, and I have to remake the material — which means filtering time is again upon me.

Amassing useful results for my confirmation report is difficult work, but it is immensely rewarding to watch the troves of data gathering and forming the beginnings of an interesting “story.” Every little piece gives me more insight into how my system works, and I really do love that. That sense of satisfaction is what makes it worth doing the repetitive, sometimes frustrating tasks it takes to get there.

For comments or queries, you can reach me at, in the comments or on Twitter as @Lady_Beaker, where I tweet about the everyday happenings of my PhD.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s