Boron Testing Methods

U.S. Borax has nearly a century of experience in laboratory research and analysis. At our Quality Lab in Boron, California, we routinely test our borate products to ensure accuracy of the boron content. To do this, we use titration to measure wt.% of B2O3.

Why Titration?

Our products have a high concentration of boron. Titration is better suited than other methods for measuring boron in this high concentration range:
  • When determining the percentage of B2O3 in sodium borate and boric acid product samples, with high concentrations of boron, the most accurate method is titration.
  • Titration is also a quicker way to determine B2O3 content. Because we run a 24-hour operation, we are able to fulfill more test requests at a faster rate than with other testing methods.

Why Not ICP?

Inductively coupled plasma (ICP) method is intended to measure trace amounts of various elements in samples. The amount of dilution required to run high boron concentration products via ICP introduces errors that impact accuracy and precision. Experts recommend that multiple elements can be measured simultaneously by ICP-OES, but boron should be measured independently (PDF courtesy of the Office of Indiana State Chemist)—thus removing the time savings benefit of ICP-OES.
In addition, ICP has some fundamental flaws when it comes to boron that make it difficult to obtain accurate and precise measurements:
  • Boron is a sticky element within the ICP tubing which can cause carry over or “memory” effects that can create erroneously over reporting results
  • The boron signal is commonly interfered with by iron (a ubiquitous element)
  • ICPs by nature have many settings and variables that make it difficult to compare between labs (eg physical components, wavelength selection, exposure times, and quantification parameters)
  • There is no internationally accepted ICP-OES method that results in high accuracy and precision, especially for samples with high boron concentration

Recommendations for Testing

AOAC International logo
We encourage labs to use the AOAC’s official titration method 949.03 (PDF) to compare results with U.S. Borax certificates of authority.

Further Testing Questions?

U.S. Borax, part of Rio Tinto, is a global leader in the supply and science of borates—naturally-occurring minerals containing boron and other elements. We are 1,000 people serving 650 customers with more than 1,800 delivery locations globally. We supply around 30% of the world’s need for refined borates from our world-class mine in Boron, California, about 100 miles northeast of Los Angeles.  Learn more about Rio Tinto.

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