Wednesday, December 1, 2010

Finding The Optimal Analytical Test Part 2

Barbara Kanegsberg
Ed Kanegsberg
Previously we discussed how regulators at the South Coast Air Quality Management District (SCAQMD) and the Independent Lubricant and Manufacturers Association (ILMA) evaluated and selected a test method to be used in SCAQMD Rule 11441 to determine the VOC level of metalworking fluids. Thermographic Analysis (TGA) was selected rather than Gas Chromatography with a flame ionization detector (GC/FID), SCAQMD Method 313L, or EPA Method 24 because TGA shows greater reproducibility and is more readily adapted to the fluids under consideration.
In the fall of 2009, as John Burke, Director of Engineering Services at Houghton International Inc., Valley Forge, PA, explains, ASTM was engaged as a neutral, consensus- driven agency to modify an existing ASTM TGA test, E1868-09.2 The ASTM activity was both rigorous and turbo-charged, because SCAQMD had to come up with a method in support of improving air quality that could be rationally communicated to the Federal regulators. Modified ASTM E1868-103 is now in place.
Burke points out that, compared with GC/FID, TGA is a relatively simple method. A fixed amount of material is added to a wing pan; the temperature is ramped up; and losses are determined gravimetrically. However, the devil is in the details and E1868-10 is no exception. Details include whether or not to begin data collection during the warm-up period, the three-dimensional configuration and material of construction of the wing pan, and the amount of liquid to be tested. Materials handling prior to test must also be specified; for example, Burke notes that fluids with a high solvent content can show evaporative losses prior to testing. “We used ASTM 691,4 including replicate samples and multiple labs to determine that we had a robust method. The tests were successful; they will be published.”
Naveen Berry, Planning and Rules Manager at SCAQMD, Diamond Bar, CA, notes that “if we had a standardized, reproducible method, we would have adopted Rule 1144 for all categories of metalworking fluids and lubricants in March 2009. “We held back on regulating metalworking fluids, especially oils and low viscosity oils with semivolatiles because the GC/FID test method was not ready for prime time. Together, industry and SCAQMD developed a TGA method that provides repeatable and reproducible results. SCAQMD is in the process of doing a second phase round robin with 313L. This will include academic, government, and private laboratories. According to our Board, for Rule 1144, we have yet to meet the robustness specified in ASTM E619. There are many variables that must be defined; GC analysis is a very fine art, as well as a science.”
Burke adds that the next step is to reformulate metalworking fluids based on the new limits. He notes that vegetable-based lubricants tend to be naturally lower in VOCs than are naphthenic lubricants and therefore could be good candidates; he notes that relative reactivity may eventually provide a more meaningful estimate of the impact of volatiles on air quality. A conference at SCAQMD is planned to discuss lubricant options and real-world findings for ultra low-VOC technology, as well as test methods.
Testing is an evolving and collaborative effort. Within your own organization, consider assembling what regulators term the “stakeholders” and obtain their input. There is no one optimal analytical test, so we suggest evaluating the options on a scientific and practical level.
Rule 1144 has improved air quality. Berry estimates that “we eliminated a little more than 3.5 tons per day from this category alone, which is almost the equivalent of shutting down three of the Southland’s major oil refineries. These were very cost-effective reductions. It is fortunate that the rule has been developed rationally, because there are encompassing implications. California is a trendsetter,” concludes Burke. “We believe the rule will morph away from California and will be adopted throughout the United States.”
  1. SCAQMD Rule 1144, “Metalworking Fluids and Direct Contact Lubricants,” Amended July 9, 2010
  2. ASTM E1868-09, Standard Test Method for Loss-On-Drying by Thermogravimetry,
  3. ASTM E1868-10 was developed as ASTM WK26130 - Revision of E1868 - 09.
  4. ASTM E691 Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

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