Quality assurance (QA) programs in the internal, on-site laboratories at fuel ethanol plants are the primary and most immediate feedback for monitoring plant efficiencies and internal QA practices. In the course of working with clients, questions have been posed regarding the accuracy and precision of the procedures and results generated by the laboratories. Not only do individual plants want to ensure their own results are accurate, but there is also interest in being able to benchmark lab results against those from other laboratories. With this in mind, Phibro Ethanol Performance Group offers a round robin program for interested customers to allow them to anonymously monitor the quality of their own results while benchmarking those results against others.&nbsp;
In the laboratory round robin program, a pretested control sample of known composition is prepared and sent to a group of participating laboratories to use in conducting their standard series of analytical tests. Client laboratories are sent a sample containing the typical sugars, acids, glycerol and ethanol components routinely analyzed by HPLC (high performance liquid chromatography). &nbsp;The HPLC instrument separates, identifies and quantifies the components of interest from a sample in most fuel ethanol plant laboratories.
In the first two round robins organized by Phibro EPG, the participating laboratories were given a time frame to analyze the control samples and send in the results. Phibro tabulated the participant&rsquo;s results, and compared those to the numbers for the control sample. The report included the concentration of each constituent analyzed by all participants and a summary of statistics from the data. Charts were produced for the mean, the upper and lower control limits (2-sigma from the mean) and the prepared (or true) values of each component. Results were reported anonymously, identified by a number known only by the participant rather than by name.&nbsp;
Participation in round robins provides laboratories with an opportunity to address several questions they may have about their analyses, including:
1. How accurate are my results versus the other participants and the actual control result?
2. Does my method, including such things as calibration practices or type of instrument, introduce a bias from the known value or does it provide results in a range similar to the other participants?
3. Do I misidentify or fail to detect constituents in the sample when compared to the other participants?
The Phibro team went beyond a simple representation of the tabulated results to compare other factors that may impact results, using a color-coded key to reflect the types of equipment and calibration practices in use at participating laboratories. The factors compared for the HPLC round robin included:
&bull; The instrument manufacturer. &bull; The column manufacturer. &bull; The length of column, whether long or short. &bull; The frequency of calibration. &bull; The source of the HPLC calibration standard, whether purchased from a commercial source or prepared in the lab.
The accompanying charts answer common questions about how some of those factors impact results. The top chart, for instance, compares the results to see whether a short or long column provides a better determination of the glucose polymers (dextrin or DP4+, maltotrios and maltose). The middle chart begins to answer the question of whether the frequency of equipment calibration affects the accuracy of lab results.
Based on feedback from the first two rounds, Phibro EPG plans to expand the scope of the round robin studies to include additional microbiological and chemical analyses conducted at fuel ethanol plants. This program is a key initiative as part of Phibro&rsquo;s ongoing customer support program to assist in optimizing customers' plant operations. &nbsp;It is the goal of Phibro EPG that future round robins will continue to provide clients with a resource to supplement internal laboratory testing and become an integral part of their own quality assurance programs.
Author: Wayne Mattsfield Manager, Analytical and Microbiological Services Phibro Ethanol Performance Group 651-641-2821 Wayne.Mattsfield@phibrochem.com&nbsp;

Most ethanol plant labs analyze sugars, acids, glycerol, and ethanol components using HPLC (high performance liquid chromatography). The HPLC instrument separates, identifies, and quantifies the components of interest.

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The green line in the chart above is the value of the control sample. The chart shows DP4+ (Dextrin) results in wt % by column length. The broken red line is the mean of all results, and the broken blue lines are the upper and l

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These two charts show lactic acid results in wt%, the one above by frequency of instrument calibration, shows increased calibration frequency did not improve the quality of the results. The chart below compares the same results by the ma

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Quality assurance programs in ethanol plant labs is the primary and most immediate feedback tool for monitoring plant efficiencies and internal practices, but only when procedural accuracy and precision are in place and working right.

Round Robins Give Lab Managers Feedback on Test Methods

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