One of the questions we receive from time to time at GoldBio is whether purity really matters when it comes to chemicals. We can understand that question. There is a huge variety of “grades” with different purities available for almost every chemical on the market. Additionally, the grades/purities from one supplier do not always match exactly with that of a second supplier, so we know that it can be very difficult to compare otherwise seemingly equivalent products. What really are the differences between common grades such as Ultra Pure, ACS, Biotechnology, Reagent or HPLC? And which one should you use?

In a small lab, the answer is typically, “use whatever is already available!” But if you are designing an experiment from scratch or want the experiment done right, you want to make sure that the reagents you’re using are the right ones for the job. There are differences between the grade types that might be important for specific applications. For instance, “Ultra Pure” is a grade that signifies that the chemical has a purity exceeding more common grades. “ACS” is a grade for chemicals that specifically conform to the requirements of the American Chemical Society (for that chemical). However, Biotechnology Grade or Tissue Culture Grade might have an equal level of chemical purity (98-99% in some cases) as the Ultra Pure or ACS, but they are further purified to remove more specific contaminants, such as nucleases or bacteria, which could cause havoc in specific experiments. In those situations, are you really sure you want to use that ACS grade chemical (that’s been on the shelf for 3+ years and opened several dozen times) for your tissue culture experiment that might take you the better part of 3 months to conclude? Trust me, it really is better if you get the appropriately graded chemical.

Of course, chemical purity is still important. For instance, Goldbio’s Luciferin is 99.7-99.8% pure, the highest purity luciferin available on the market!** Most other suppliers have a minimum purity of only 98% (and sometimes, as low as 95%)! Maybe that doesn’t sound like much, but let’s do the math anyway. If 1 gram of 98.0% luciferin is dissolved in 25 ml buffer (a fairly standard dilution for in vivo assays) there would be 0.02 g of any potential contaminants. Again, that doesn’t sound like much, but that actually equates to 0.8 g per liter. If our theoretical contaminant has a molecular weight of 1000 g/mole, then the contaminant would be at a concentration of 800µM! That’s more than high enough to inhibit some enzymes in a cell.

Luciferin purity is principally quantified by HPLC, and any impurities which may be left in the chemical are typically labeled as “unknown impurities”. The sensitivity and reliability of HPLC make common impurities fairly easy to distinguish and separate, so any unknown impurities may give you reason to pause. Of course, these unknown impurities may or may not be detrimental to an experiment. But just like in the previous example, are you really sure you want to trust a reagent with a lot of unknown impurities? Can you really be sure that potential impurities in your luciferin will be benign and have no side-effects on your 6-12 month mouse or rat study?

At GoldBio, we understand that question. It is why we strive to provide reagents, like luciferin, that are the best quality for your experiments. It is why we test our reagents personally to guarantee their efficacy. And that is why you trust GoldBio to provide those reagents for your research.

It’s just good science.

We would love to hear from you, so if you have any questions about any of our products, you can email us at:!

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