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It should be second-nature to a good laboratory technician to identify the key areas that need to be consistent to yield a consistently reproducible, standard laboratory method. Of course, the experience, attitude and training of the lab tech is of prime concern for any lab manager.
However, experience really comes into play when something goes horribly wrong and, if you have good staff, they will methodically identify possible causes of inconsistency leading to assay failure and work through them to determine the cause of variability – or even assay failure.
There are several key elements to consider when trying to hunt down where inconsistency has crept into a method.
1. Reaction Vessels
All tubes are not created equal. There are a wide range of suppliers for every conceivable reaction vessel on the market, from platinum crucibles, to microtubes. Whether they’re plastic, glass, or something more exotic, having a consistent supplier of the same vessel will be key.
If it’s a re-usable rather than a disposable reaction vessel, then the method of cleaning, and indeed the cleaning materials used will have an effect on any chemistries.
2. Chemical Stocks
The above brings us nicely onto the subject of chemicals. Just like reaction vessels are not all the same, neither are chemicals. Just because it says “sulfuric acid” on the bottle, doesn’t mean the one from eBay, and the one from someone like Sigma Aldrich are going to be the same. Make sure you have a consistent supplier of quality chemicals so that you can reduce the risk of any contamination.
And whilst on the subject of chemicals – make sure they are stored correctly. If they need to be kept cold, invest in a decent fridge, if they don’t like the light, don’t leave them on the window ledge!
3. Assay Mix
Even with the best reagents and the perfect reaction vessels, there are other, less subtle events that can affect consistency. Pipetting is a great example – whilst everyone understands the process, not everyone does it the same way every time. All it takes is one slip of the thumb during a pipetting step, and perhaps an extra microliter or two makes its way into the reaction, and the next time perhaps it comes up short. Less reagents, less substrates, lower consistency.
Make sure you buy the best. Of course, we’re going to be biased and say that means paying a visit to the Vitl website, but in reality, it’s a good rule of thumb to buy the best you can afford for practical purposes, not because you want the latest brand or the newest model. On top of that, once you’ve purchased your new instrument, keep it that way with regular servicing and maintenance.
Vitl Life Science Solutions is a global leader in the design, development and manufacture of high-quality laboratory and analytical instruments. Vitl products are suitable for applications such as, ELISA, DNA isolation, enzymatic reactions and sample incubation, and provide rapid and accurate results to researchers world-wide.