How to use phase-contrast microscopes like a pro

Our step-by-step guide to getting your wastewater samples under the microscope, by Frank J. DeOrio

Let’s face it, microscope slides are not always the easiest things to use; they are small, fiddly, and we often have to re-do the sample a number of times before it’s ready to go under the microscope. Having prepared tens of thousands of wet-mount slides in my years, and been asked for the right technique almost as much, here are my top tips for preparing them.

Our top 12 tips to manage your microscope and sample:

1. Firstly, have a clean cover slip and slide.
2. Use a pipette to grab a sample of the settled Mixed Liquor Suspended Solids (“MLSS”, or more well known as sludge, bugs, or biomass. Put finger on top of pipette until the immersed end of a wide tip pipette reaches the bottom of sludge sample. Release your finger to allow sludge into the pipette. Replace your finger on top of pipette and remove the pipette from the sampler beaker. A long tipped disposable eyedropper may also be used, but make sure that you dip down into the settled mass for your sample.
3. Place one drop of MLSS from the pipette to the middle of the glass slide.
4. Pick up cover slip by two corners.
5. Pull cover slip along glass slide towards drop of MLSS.
6. As soon as cover slip touches drop of MLSS allow coverslip to fall onto glass slide.
7. Blot away excess liquid that may still be on the slide with a lab tissue.
8. Pick up glass slide. Place on microscope stage.
9. Move stage up to within approximately 1/8 inch of objective on 10 X (100X magnification).
10. Use the coarse, and then fine adjustments on the microscope to bring the MLSS into the field of focus.
11. Turn to 40 X (400X magnification) and repeat as described above to prepare to capture your image.
12. Capture your well-focused image either by your attached camera equipment, or by using your cell phone camera with a cell phone camera adapter.

The key to using your microscope is having well-prepared samples, and a clear view so you can see what’s happening under magnification. Check out our blog post for how to identify and manage the lifeforms in your plant using a microscope.

And while you’re here… opseyes makes the identification of filamentous easy. Simply upload four photos of your sample to our website, and we’ll identify your bugs and tell you what you need to do to fix any issues. And best of all? You can try it for free (no credit card details needed). Just make an account and you’re ready to go.