Ethanol HPLC: Making Standards More Specialized

by Tom Bryan (Ethanol Producer Magazine) With an impeccable production partner, deep roots in ethanol and a customer base looking for tailored HPLC products, Enertech Solutions is elevating reference materials through customization and robust accreditation.

The HPLC is the heart of every ethanol lab; it’s the eyes and ears of the entire process and gives daily critical information that directs the entirety of plant operations. Ethanol plants use HPLC to monitor environmental compliance, process conditions and the progression of ethanol fermentations—the conversion of sugars to ethanol, ethanol breakdown to acetic acid, yeast health and more. The process tracks analyte molecules as they separate and flow through an HPLC column; the analyte is characterized by comparative analysis to a manufactured reference standard. Reference materials have been used for decades, but until recently didn’t always offer the precise results ethanol producers wanted. The problem with established catalog standards, Smith says, is that a one-size-fits-all approach was too often not meeting the needs of an increasingly diversified ethanol industry producing not only fuel ethanol, but specialized alcohols and a wide range of high-value coproducts.

It is very difficult for an ethanol plant to carry out an optimization to get even 0.2% more alcohol out of a batch if the facility’s reference standards have the slightest variability. “But that’s what we make possible,” he says. “Those very tight optimizations call for reference materials that are absolutely dead-on accurate.”

To be clear, there is not a crisp line between a catalog standard and a custom-manufactured one, says Bezhig McMurtrie, a former ethanol plant lab manager who now works in sales and customer support at Enertech. “Actually, from the moment a producer accepts formulation, that new standard is officially their catalog item,” she says. “But, if over time that standard no longer fits their needs, it can be changed. So, think of it as a catalog standard that’s flexible.”

For those not familiar with the HPLC process, Biggerstaff explains that it’s not just a matter of designing singular reference standards for ethanol producers, but whole calibration sets that synchronize with a plant’s analytical objectives and fermentation profiles. “Early on, a standard calibration routine with, say, 13 components to it, would simply have higher and higher concentrations [of the same makeup], so everything kind of scaled the same in those calibration sets. That was standard operating procedure,” he says. “But actual fermentations have very high starch and sugar and very low ethanol when they start. Later, the ratios change with each level, so that they end up being high ethanol, low sugars. We’ve designed calibration sets to mimic the fermentation process so the actual responses and accuracies for those runs and calibration points are essentially dead on to what’s happening in the fermenter. That was not being offered to ethanol producers previously.”

McMurtrie concurs, saying that when she was working in ethanol production, and an early customer of Enertech’s reference standards, her lab followed the exact model described by Biggerstaff, dropping sugars from high to low and ethanol from low to high—across a five-level calibration set, achieving an ideal R2 of 1.0. “It was phenomenal for a fermentation set with that many components,” she says. “And there was nothing like it on the market.”

McMurtrie adds, “There should never be mystery peaks in reference standards, yet we see that with some of the products available to the industry. When they show up, they can interfere with the integration of intended analytes.”

McMurtrie also explains that most reference standards on the market are still made with the average fermentation profile in mind, but it’s hard to find an “average” plant these days. “Everyone in the ethanol industry knows each plant is very unique, in so many ways,” she says. “Custom standards allow producers to focus on specific components and ranges that are relevant to their own products and operation.”

McMurtrie adds that this includes not only HPLC standards but also standards for gas chromatography (GC) for denaturant, fusel oils and other impurities that are needed in the U.S. Pharmacopeia (USP) market, as well as ion chromatography (IC) standards.

Advantaged by Accreditations
The reference standards Enertech delivers to ethanol plants are not only tailored and custom formulated to the needs of today’s producers, but backed by very high levels of accreditation, pre-delivery analysis and manufacturing quality control.

In addition, the company adheres to ISO 17034 for the actual manufacturing of the reference materials. “And what that says is that we’re making products in essentially the same manner and level of quality as NIST—which is the gold standard,” Biggerstaff says. “So, the whole process is highly documented. Everything is traceable. Everything is analyzed.” READ MORE