Defining Key Terms

There has been plenty of confusion about the laboratory side of compliance with ASTM D6751 specification for biodiesel and the BQ-9000 reduced specification, otherwise known as the critical testing criterion. With many companies touting their high-quality biodiesel product, or touting a specific process or analytical instrument to produce or discern ASTM-grade biodiesel, the phrase ASTM-grade biodiesel itself has become an industry buzzword, with unfortunate consequences. Being in the analytical chemistry analyzer business for more than 22 years, and selling complete laboratories specifically to the biodiesel industry for the past five years, I would like to set the record straight as to the future use of the term ASTM-grade biodiesel and the critical testing criterion.

Like many other words or phrases in the English language, once they start to become overused, it slowly loses its exact meaning. The phrase "you know," for example, used to be defined as "you understand." Now you hear it overused all the time, and most of the time it means "um-m-m." I am afraid that the phrases "ASTM grade biodiesel," "reduced specification" and "critical testing criterion" are falling prey to this same overuse syndrome as "you know." You know?

The ASTM D6751 specification requires every single test be run on each production batch of biodiesel before it can be called ASTM-grade. That specification includes flash point (ASTM D93) or alcohol content (EN 14110); water and sediment (ASTM D2709); kinematic viscosity (ASTM D445); sulfated ash (ASTM D874); sulfur (ASTM D5453); copper strip corrosion (ASTM D130); cetane number (ASTM D613); cloud point (ASTM D2500); carbon residue (ASTM D4530); acid number (ASTM D664); cold soak filterability (ASTM D6751-Annex A1); free and total glycerin (ASTM D6584); phosphorus content (ASTM D4951); calcium and magnesium, combined (EN14538); sodium and potassium, combined (EN14538); vacuum distillation (ASTM D1160); and oxidation stability (ASTM 14112). There are alternate methods allowed, but those listed are the referee if any dispute should arise. Each and every one of the tests above are the required by almost every state in the union as a minimum to be called biodiesel. If you are marketing your biodiesel outside the U.S., then several other tests would also be required.

If a company claims that its process can provide ASTM-grade biodiesel from waste vegetable oil that has a sulfur content of 38 ppm, without somehow removing that sulfur with a pretreatment process, then they are not being truthful in their claims. Petroleum companies have spent millions of dollars for treatment technologies to get rid of the excess sulfur to make the ultra-low sulfur diesel that the U.S. EPA requires, and biodiesel companies will not be exempt from those same requirements if they are using higher sulfur-content feedstock.

The only way around these stringent specifications are if your facility becomes a BQ-9000 certified producer. In the BQ-9000 regulations, once your process passes all the ASTM D6751 specifications listed above on the first seven batches produced, and if your feedstock remains the same, then you can start running the reduced specification or the critical testing criterion for every batch and only test monthly or yearly on the remaining tests.

The critical testing criterion includes eight tests: flash point or alcohol content; water and sediment; sulfur; cloud point; acid number; cold soak filterability; free and total glycerin; and oxidation stability. If you change your feedstock, you are back to square one in the BQ-9000 process of being enabled to run the critical testing criterion only.

Some analytical instruments companies are claiming that their infrared technology analyzer is able to discern all the critical testing criterion. They are also not being truthful in their claims. The only way to analyze for sulfur down to the maximum 15 ppm specification limit is by using the referee method ASTM D5453 UV-Fluorescent technology (and some alternate method listed in ASTM D6751, which does not include IR). Analyzers using IR technology simply cannot do elemental analysis. The whole science behind IR is based on molecular bonds, thus elemental analysis is impossible with IR.

I propose that we use the phrases critical testing criterion and ASTM-grade biodiesel the way they are defined by ASTM and BQ-9000. We should be very careful not to fall in the "you know" syndrome when it comes to our nation's fuel in the future. You know?


Mark Fashian is president of Biodiesel Analytical Solutions and director of Mcgyan Biodiesel LLC. Reach him at (740) 369-5475 or [email protected].