ENVIRONMENTAL METHODS (UNITED STATES)
The USEPA Office of Solid Waste (SW-846 Methods) -
Applying BLLE to the performance-based 8000 series methods requires an initial demonstration of capability (IDOC) and a method detection limit study (MDL) meeting or exceeding the particular analytical method (8270, 8081, 8082, 8151, 8141, etc.) requirements. This requirement is necessary for any technique employed. Excellent results are particularly easily obtained with this automated technique.
The USEPA Office of Water (Clean Water Act Methods) -
The management of the USEPA Office of Water has particularly acknowledged use of the BLLE procedure under the flexibility provisions of the 600 series methods as an extension of the separatory funnel.
The following is an excerpt from a January 14, 2015 letter from the Clean Water Act Alternate Test Procedure (ATP) Coordinator (the federal USEPA official in charge of wastewater method approval processes) regarding Method 625 specifically :
"Based on review of the information sent to me regarding the use of the Summit Environmental Technologies (SET) sponsored bottle extractor for use in collection and liquid-liquid extraction of aqueous samples when performing analyses by EPA Method 625, I concur with your understanding that the use of the bottle extractor would fall under the flexibility to modify methods allowed at 40 CFR § 136.6.
A user wishing to use the Summit Environmental Technologies (SET) sponsored bottle extractor when performing analyses for CWA compliance monitoring must comply with 40 CFR § 136.6,(b) Method modifications: “The user must notify their permitting authority of the intent to use a modified method. Such notification should be of the form ‘‘Method 625 has been modified within the flexibility allowed in 40 CFR 136.6”.
The organization that uses the modified method must also document the results of all QC tests and keep those records, along with a copy of the method write-up or addendum, for review by an auditor as specified at § 136.6,(b)(2)(ii) Requirements for documentation..
As mentioned previously in this email, my office has recently completed a revision of EPA Method 625. This revision, EPA Method 625.1, is planned for inclusion in the next MUR which is scheduled for publication on the Federal Register in early 2015. EPA Method 625.1 includes language that will expressly allow the use of alternate extraction procedures provided that certain requirements specified in the method are met (e.g., documented method detection limit studies, documented precision and accuracy studies and meeting all other QC acceptance criteria specified in the method). However, until EPA Method 625.1 goes through the rule-making process (proposal, responding to any public comments and promulgation of the final method in the Federal Register) use of the method for compliance monitoring purposes would need to be approved as a limited use ATP by the appropriate Regional ATP Coordinator".
Regards,
Lem
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Lemuel (Lem) Walker, Jr.
Clean Water Act ATP Coordinator
U.S. Environmental Protection Agency
Office of Science and Technology
Engineering and Analysis Division (EAD)
1200 Pennsylvania Avenue, NW
Mail Code - 4303T
Washington, DC20460
The USEPA Clean Water Act Alternative Test Procedure (ATP) Coordinator is expressly stating that the new methods (625.1, 608.3, etc.) are written to provide guidance to promote the use of innovative new procedures (naming BLLE specifically). Clean Water Act officials are acknowledging the importance of promoting new technologies following the performance-based approach of the Office of Solid Waste.
These new methods have now passed through Final Rule - The Administrator, Scott Pruitt, signing into law the final rule on August 7, 2017.
If you use a modification to an approved 40 CFR Part 136 method and document the modification as described at 40 CFR 136.6, you will no longer receive or require a letter from EPA. The March 12, 2007 Methods Update Rule that promulgated § 136.6, as modified by the May 18, 2012 Methods Update Rule allows the regulated community more flexibility to modify approved methods without EPA review, provided certain requirements are met.
This regulation allows the analytical community greater flexibility to modify approved methods to lower the costs of measurements, overcome matrix interferences, or otherwise improve the analysis without EPA review. Laboratories that modify Part 136 methods may be private, public or commercial and may conduct analyses for one or more clients or facilities
The following are some excerpts from Method 625.1 (Dec 2016):
Section 1.6 - "This method is performance-based. It may be modified to improve performance (e.g., to overcome interferences or improve the accuracy of results) provided all performance requirements are met".
Section 1.6.1 - "Examples of allowed method modifications are described at 40 CFR 136.6" (Section 4iii of 136.6 states that "Changes between automated and manual sample preparation, such as digestions, distillations, and extractions; in-line sample preparation is an acceptable form of automated sample preparation for CWA methods.
Section 8.1.2 - "In recognition of advances that are occurring in analytical technology, and to overcome matrix interferences, the laboratory is permitted certain options (Section 1.6 and 40 CFR 136.6(b)) to improve separations or lower the costs of measurements. These options may include alternate extraction, concentration, and cleanup procedures (e.g., solid-phase extraction; rotary-evaporator concentration; column chromatography cleanup), changes in column and type of mass spectrometer (40 CFR 136.6(b)(4)(xvi))".
Section 10.1 - “This section contains procedures for separatory funnel liquid-liquid extraction (SFLLE) and continuous liquid-liquid extraction (CLLE). SFLLE is faster, but may not be as effective as CLLE for recovery of polar analytes such as phenol. SFLLE is labor intensive and may result in formation of emulsions that are difficult to break. CLLE is less labor intensive, avoids emulsion formation, but requires more time (18-24 hours) and more hood space, and may require more solvent. The procedures assume base-neutral extraction followed by acid extraction. For some matrices and analytes of interest, improved results may be obtained by acid-neutral extraction followed by base extraction. A single acid or base extraction may also be performed. If an extraction scheme alternate to base-neutral followed by acid extraction is used, all QC tests must be performed and all QC acceptance criteria must be met with that extraction scheme as an integral part of this method. Solid-phase extraction (SPE) may be used provided requirements in Section 8.1.2 are met.
The USEPA Office of Water (Drinking Water Methods) -
Method 508 and 515.1 have provisions for an 'automated mechanical tumbler extraction' as well as separatory funnel extraction. BLLE has been demonstrated to exceed the QC requirements of these methods using the required solvents and reagents of Section 11.2 in each of these methods.
Section 10.4 of Method 508 states specifically:
"The analyst is permitted to modify GC columns, GC conditions, GC detectors, continuous extraction techniques, concentration techniques (i.e., evaporation techniques), internal standards or surrogate compounds. Each time such method modifications are made, the analyst must repeat the procedures in Section 10.3"
Since the current language of the drinking water methods does not currently specifically state the use of BLLE, there is some risk that an auditor may object to its use for a 500 series method, even if side by side studies are shown to be superior.