Tuning criteria

Table 3.1.6 Tuning criteria (Agilent Technologies systems, perfluorotributylamine) ... 

DFTPPO Tuning Criteria for LC/MS System Performance Check Table 2.19.4... 

Several compounds, including many deuterated and fluoro derivatives, have been used in the published literature. These include fluorobenzene, pentafluo-robenzene, l,2-dichlorobenzene-d4, l-chloro-2-fluorobenzene, 1,4-difluoroben-zene, l,2-dichloroethane-d4, 1,4-dichlorobutane, and 2-bromo-l-chloropropane. U.S. EPA has set the tuning criteria for bromofluorobenzene and decafluorotriph-enylphosphine as tuning compounds for volatile and semivolatile organic compounds. (See Chapter 1.4)... 

Proscribed Tuning Criteria for USEPA Method 8270 Using Decafluorotriphenyl Phosphine... 

The tables use three different tuning criteria-integral of absolute error (lAE), integral of square of error (ISE) and integral over time of the absolute error (ITAE). Not used by Smith and Murrill, another function can be defined - integral over time of the square of the error (ITSE). Each of these is a form of penalty function representing the size and duration of error. The tuning methods aim to minimise the penalty. 

We may wish to apply very different tuning criteria. It may be more important to minimise disturbances to the manipulated flow than it is to maintain the level close to SP. This type of controller performance is known as averaging rather than tight level control. Averaging control can dramatically reduce the impact that flow disturbances have on a process. 

Process model is known An approximate model of the process may be obtained by the step response test noted earlier (see Section 12.4.2.4) (or from first prindples). When an approximate modd of the process is known we may obtain the tuning parameters directly. We use here the example of the first-order plus dead time process, since its dynamics are so representative of the polymer equipment dynamics. Here we have chosen for the tuning criteria to minimize the integral of the time-weighted absolute error (ITAE) [Eq. (96)] [7]. 

Before sample analysis, the tuning of the MS was checked by using the autotune function and run the BFB check sample. The used ISQ MS met the tuning criteria for BFB listed in the method (see Figure 4.7). 

The quantitation was based on an internal standard method, using an isotopi-cally labelled analogue of toluene. A surrogate standard was also added to the samples in order to control the long-term spectral balance stability and to check the MS tuning criteria. 

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