How much costs the 99% pure chemical compound compared to the 95% one?

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Key Takeaways

✔ Compound price is determined by the required specification—not by purity alone.

✔ Increasing purity from 95% to 99% can require disproportionately greater purification effort and significantly higher costs.

✔ The type of impurity is often more important than the total impurity level.

✔ Different industries require different impurity profiles depending on the intended application.

✔ Defining critical impurities and functional specifications enables more efficient and cost-effective custom synthesis projects.

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Quick Summary

• Compound purity alone does not determine the price of a chemical compound.
• Purification costs increase disproportionately at higher purity levels.
• The nature of impurities is often more important than their percentage.
• Different applications require different impurity specifications.
• Defining a chemical specification instead of only requesting a purity level leads to better technical and commercial outcomes.

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A common question we are facing nearly every day. At first sight, the answer should not be that difficult. Everyone certainly expects that the price will be (somewhat) higher. In fact the expectations range from about 4% to a ballpark figure of a low two digit number.  However – in reality – the answer also can be something like 300%!

This needs to be explained.

Most people outside chemistry really struggle to understand this background.

• First, there is the generally applying “Pareto Principle” roughly saying that the last 20% of any task completion require 80% of the total resources and vice versa.

https://en.wikipedia.org/wiki/Pareto_principle

This principle was not specifically defined for the purification of chemical compounds, but it mirrors the general fact that each subsequent (purification) step is more tedious than the preceding one. Think of cleaning a dirty pan: the removal of 90% of the coarse dirt is easy, the removal of the last stains might take …

So, increasing the purity from 95 to 99% is substantially more expensive than to go from 91 to 95%.

This is only part of the truth:

• Second, we have to dig deeper into the term “purity”. One has to accept that this is a (very) “relative” one. 95% means 5% impurities. Impurities are by definition any foreign substance – regardless of their nature and relevance. And exactly, here, the real answer to the initial question can be found: “It depends”

Some impurities are being regarded as more “critical” than others. This evaluation differs from product to product and – with a given product – varies from application to application.

Everything clear now?

An example:

A 95% sodium chloride containing 5% water is absolutely OK for biotech – no need for purification. The same sodium chloride, however, might be absolutely useless for the electronics industry. The purification here (simply a “drying” step) may cost 20 €/kg to reach 99%.

Another 95% sodium chloride may contain 1% sodium cyanide and 4% water. It would be too toxic biotech. In electronics the water still might be more critical than the azide. The purification to 99% via drying is already more expensive (all water needs to get removed – not just 4 of 5 perc. points) – this may cost 60 €/kg. In addition, the result is different (1% azide instead of water). An alternative would be to remove all azide and most of the water – one gets the same quality as with a), however causing much more costs… let’s assume 190 €/kg.

So, the answer to the initial question:

• define critical and non-critical components and
• request the price of a SPECIFICATION (not of a purity).

How application-specific requirements are translated into a testable chemical specification and a reliable pathway to recurring batches is explained on the ChiroBlock page Custom Synthesis of Established Compounds to Specification and Reliable Supply.

https://hellobio.com/purity-guide-for-life-scientists

Interactive Graphic – What Influences the price more? Purity or Quantity?

Adjust the parameters and see the effect on costs:

Relative Investment Index 100

Moderate Baseline

Base 4 Quantity +4 Purity +8

Adjust the assumptions

Explore the Price Effect

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Required Purity

98.0%

80% 95% 98% 99.9%

LowIncreasingStrong

Requested Quantity

10 g

50 mg 100 mg 500 mg 1 g 2 g 5 g 10 g 100 g 500 g 1 kg 5 kg 10 kg

50–100 mg have almost no additional effect. From 500 mg to 100 g, quantity increases moderately; 500 g marks the first scale-up effort, and larger effects follow above 500 g.

Purity is the stronger cost driver.

At 98.0% purity and 10 g, purity adds more relative cost than quantity.

Purity effect: high Quantity effect: very low

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