In a nutshell, the spectrophotometer operates as follows: One loads the sample, and then takes measurements using different wavelengths of ultraviolet light. A wavelength of 260 nm will indicate the presence of DNA, a wavelength of 280 nm will indicate protein contamination, and a wavelength of 320 nm is used to measure the turbidity of the sample, i.e. other possible contaminants. From these measurements, the operator can then use mathematical formulas to calculate the DNA purity and DNA concentration of the sample. This allows the operator to determine if his extraction protocols have been successful at removing DNA from his source material.
The Helios spec that we have in the lab was originally purchased more than a decade ago, and subsequently the knowledge needed to operate it has been lost. Therefore, I've spent most of my time this week educating myself as to the nuances of this particular brand. It's been a bit of a search, as the model was discontinued in 2011, and online technical support is no longer available. We still have the instruction manual, but it has little more information in it other than programming. Nothing is available in the manual about actually installing reading protocols. However, with a little diligence I have figured it out and am prepared to now use it to measure my samples.
Therefore, the remainder of my lab time this week will be spent extracting DNA from my E. coli cultures and then running them through the spectrophotometer to verify the protocol's success. More on that methodology and any successes or failures will follow on this blog next week. Until then, please enjoy the photo below of the machine that has taken all of my attention this week.
Cheers!
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