Performance-based methods

For use with design option B, performance based method, para. PL-3.7.1(b)(2). 

This is a performance-based method that avoids the use of chlorofluorocarbon solvent. The method is applicable to aqueous matrices, using -hexane as the extraction solvent and gravimetry as the determinative technique. Because hexane is a hydrocarbon solvent, and if this solvent is employed for extraction, the method performance cannot be evaluated by IR measurement. The substances that may be determined by this method are relatively nonvolatile hydrocarbons, vegetable oils, greases, waxes, animal fats, and related materials. The method permits the use of other extraction solvents also, provided that the QC criteria are met. 

Under the PBMS approach, prescriptive analytical methods of today will give way to performance-based methods that are focused on the analysis of project-specific contaminants of concern under project-specific QC requirements. These QC requirements will be selected based on the need of the regulatory program that requires data collection and will support the production of valid data of known and documented quality. 

This does not mean that the EPA will give the laboratories a free hand in conducting analysis. The laboratories embarking on the development of the PBMS will have to validate the new performance-based methods according to the EPA requirements and submit their validation documentation to the EPA for approval prior to using them for project work. The EPA guidance for PBMS may be found at http //www.epa.gov/epaoswer/haswaste/test/pbms.htm. 

In general, performance-based methods shall be used in surveillance and operational monitoring. They shall be described clearly, be properly validated and give laboratories the flexibility to select from several options when possible and meaningful. Irrespective of what method is applied in chemical monitoring, certain minimum performance... 

Should it take a decade or two for a newly developed method to become EPA approved The future appears not to emulate the past as the second broad mental framework is taking hold the agency calls it performance-based method (PBM). 

Performance-based methods are an empowering concept. PBMs enable analysts and the laboratories that they work in to become more creative and encourage attempts to develop alternative methods to perform TEQA. Many of these alternative approaches are much more cost-effective while yielding the same outcome. In other words, the performance of the method is the same, a deliverable outcome, and the inputs are much reduced in cost and labor. Alternative methods of sample preparation will be discussed in Chapter 3. 

At around the same time, much of the rest of the world was putting together regional or local performance-based method standardisation i.e. statistical performance characteristics were specified instead of analytical techniques. 

In the previous section we described several internal methods of quality assessment that provide quantitative estimates of the systematic and random errors present in an analytical system. Now we turn our attention to how this numerical information is incorporated into the written directives of a complete quality assurance program. Two approaches to developing quality assurance programs have been described a prescriptive approach, in which an exact method of quality assessment is prescribed and a performance-based approach, in which any form of quality assessment is acceptable, provided that an acceptable level of statistical control can be demonstrated. 

In a performance-based approach to quality assurance, a laboratory is free to use its experience to determine the best way to gather and monitor quality assessment data. The quality assessment methods remain the same (duplicate samples, blanks, standards, and spike recoveries) since they provide the necessary information about precision and bias. What the laboratory can control, however, is the frequency with which quality assessment samples are analyzed, and the conditions indicating when an analytical system is no longer in a state of statistical control. Furthermore, a performance-based approach to quality assessment allows a laboratory to determine if an analytical system is in danger of drifting out of statistical control. Corrective measures are then taken before further problems develop. 

Williams, J. C., 1989, A Data-Based Method for Assessing and Reducing Human Error to Improve Operational Performance, Proceedings of the 1988 IEEE Fourth Conference on Human Factors and Power Plants, Monterey, CA, June 5-9, pp 436-450, IEEE. 

This is accomplished using the ECFC and the Critical Human Achon Profile (CHAP), a fask analysis-based method used to identify the most critical actions necessary for the performance of the task. Change Analysis is a technique for investigating the role of change in accident causation. It will be described in Section 6.8.6. 

Quantum-chemical calculations which utilize the density functional theory (DFT) are now perhaps amongst the most frequently performed because of their relatively low cost and high accuracy. Structural results obtained from DFT based methods are often as good as those derived from MP2 calculations. It is well documented that DFT methods, especially those involving hybrid functionals such as B3LYP, B3P86 and B3PW91, yield reliable... 

Comparisons of the accuracy and efficiency for three numerical procedures, the direct summation, DC-FFT-based method and MLMI, are made in this section. The three methods were applied to calculating normal surface deformations at different levels of grids, under the load of a uniform pressure on a rectangle area 2a X 2fo, or a Hertzian pressure on a circle area in radius a. The calculations were performed on the same personal computer, the computational domain was set as -1.5a=Sx 1.5a and -1.5a=Sy 1.5a, and covered... 

High performance spectroscopic methods, like FT-IR and NIR spectrometry and Raman spectroscopy are widely applied to identify non-destructively the specific fingerprint of an extract or check the stability of pure molecules or mixtures by the recognition of different functional groups. Generally, the infrared techniques are more frequently applied in food colorant analysis, as recently reviewed. Mass spectrometry is used as well, either coupled to HPLC for the detection of separated molecules or for the identification of a fingerprint based on fragmentation patterns. ... 

Whilst for the analysis of plant material for cannabinoids both GC and HPLC are commonly used, in analytical procedures the employment of GC-based methods prevails for human forensic samples. Nonetheless, the usage of HPLC becomes more and more of interest in this field especially in combination with MS [115-120]. Besides the usage of deuterated samples as internal standards Fisher et al. [121] describe the use of a dibrominated THC-COOH (see 7.5). The usage of Thermospray-MS and electrochemical detection provide good performance and can replace the still-used conventional UV detector. Another advantage in the employment of HPLC rather than GC could be the integration of SPE cartridges, which are needed for sample preparation in the HPLC-system. 

I 75 Prediction of LogP with Property-based Methods Tab. 15.2 Performance of algorithms. 

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