Week Seven – NanoDrop!

Really not a lot happened this week. On Monday, I operated a NanoDrop machine to record the protein concentrations of some interstitial fluid samples (exciting). On Tuesday, I got my annual check-up and MenB vaccine for college, which absolutely knocked me out for several days. Some things came up with my graduate student mentor, so I ended not coming back to the center for the rest of the week. On Thursday, at the eye doctor, I found out my eyesight had deteriorated once again. 

So, the NanoDrop machine. A kind of advanced spectrophotometer, it measures the absorbance of liquid samples by recording the loss of light intensity as a sent beam travels from the emitter to the detector. The machine then does some fancy calculations and incorporates a few corrections to arrive at a protein concentration. The coolest thing, though, is that it can, through the transmittance of different wavelengths, distinguish proteins, nucleic acids, and contaminants. Even those that absorb at the same wavelengths! (I assume some must be different for it to work correctly.) 

As with the operaton of any scientific instrument, calibration is crucial. I didn’t actually calibrate the NanoDrop machine (which is a somewhat lengthy process), but I “blanked” it every 30 minutes or so of operation. That means I loaded 1 μL of molecular biology grade water (“No DNase, RNase, or protease activity detected” per the Thermo Fisher website), pressed the “Blank” button, and let it do its thing. I assume the accuracy of measurement can drift slightly due to outside conditions, like humidity and temperature, and that’s why it’s recommended to re-blank every 30 minutes if processing a lot of samples. 

For my Tuesday work, I pipetted roughly 1 μL of sample onto a small glass surface (above the detector), gently pulled the arm of the machine (which contains the emitter) down so it was aligned with the detector, and waited around 5 seconds for the machine to communicate its results. 0.315 (mg of protein per mL of sample). Time to clean both surfaces that touch the sample (the pedestal and the corresponding portion of the arm) with deionized water and lint-free wipes, the same as for your glasses. Again, with a different sample. 0.183. Again. Error: broken column detected. I thought that meant a bubble appeared, but apparently it can signify too little sample volume has been loaded. Redo and, voila: 0.087. 

I recorded the data each time in a table on a sheet of paper and that was my Tuesday. Better than doing my taxes, however, since that was Tax Day. 

“Ultrapure™ DNase/RNase-Free Distilled Water.” Thermo Fisher Scientific – US, 2023, https://www.thermofisher.com/order/catalog/product/10977015?gclid=CjwKCAjw6IiiBhAOEiwALNqncYczzP_MfK3Y_fo5EQ0ESm17aZ3BFBi0bLzns55b9A_sVM_AeT26-bhoCYIMQAvD_BwE&ef_id=CjwKCAjw6IiiBhAOEiwALNqncYczzP_MfK3Y_fo5EQ0ESm17aZ3BFBi0bLz-ns55b9A_sVM_AeT26bhoCYIMQAvD_BwE%3AG%3As&s_kwcid=AL%213652%213%21572074520820-%21e%21%21g%21%21molecular+biology+grade+water%2111199571103%21118288779988&cid=bi-d_mol_pch_r01_co_cp1358_pjt00-00_bid00000_0se_gaw_nt_pur_con.