Analytical procedure linearity

The linearity of an analytical procedure is its ability (within a given range) to obtain test results, which are directly proportional to the concentration (amount) of analyte in the sample. 

The range of an analytical procedure is the interval between the upper and lower concentration (amounts) of analyte in the sample (including these concentrations) for which it has been demonstrated that the analytical procedure has a suitable level of precision, accuracy and linearity. 

Residue study protocols typically either include quality specifications for analytical procedures or refer to a written analytical method that includes such specifications. The protocol for an LSMBS should also include analytical quality specifications, either directly or by reference to a method. Analytical specifications usually include minimum and maximum recovery of analyte from fortified control samples, minimum number of such fortifications per set of samples, minimum linearity in calibration, minimum stability of response to injection of calibration solutions, and limits of quantitation and of detection. 

All solutions of Eqs. (3) such as that by Yu and Sparrow (Yl) yield the velocity profiles in each phase as a function of the interfacial position h and the pressure drop. The volumetric flow rates Qt and Q are obtained by integrating each velocity profile over the respective phase cross-sectional area. The ratio of the flow rates can then be determined as a function of only the interfacial position, and since the volumetric flow rates are known, this yields an implicit fourth order equation for the interfacial position h. The holdups Rt and Rn can be calculated once the interfacial position is known. Since each equation for the volumetric flow rates is linear with respect to the pressure drop, once the interfacial position is known the pressure drop may be easily computed. An analytical procedure for determining pressure drop and holdup for turbulent gas-laminar liquid flows has been developed by Etchells (El) and verified by comparison with experimental data in horizontal systems (A7). 

Perhaps the most discouraging type of deviation from linearity is random scatter of the data points. Such results indicate that something is seriously wrong with the experiment. The method of analysis may be at fault or the reaction may not be following the expected stoichiometry. Side reactions may be interfering with the analytical procedures used to follow the progress of the reaction, or they may render the mathematical analysis employed invalid. When such plots are obtained, it is wise to reevaluate the entire experimental procedure and the method used to evaluate the data before carrying out additional experiments in the laboratory. 

Sample preconcentration was performed by means of an automated on-line SPE sample processor Prospekt-2 (Spark Holland, Emmen, The Netherlands). Oasis HLB cartridges (Waters, Barcelona, Spain) were used to preconcentrate cannabi-noids present in the water samples whereas isolation of the rest of the compounds was done in PLRPs cartridges (Spark Holland). Before extraction, influent samples were diluted with HPLC water (1 9, v/v) to reduce matrix interferences and to fit some analyte concentrations, e.g., cocaine (CO) and benzoylecgonine (BE), within the linear calibration range. A sample volume of 5 mL was spiked with the internal standard mixture (at 20 ng/L) in order to correct for potential losses during the analytical procedure, as well as for matrix effects. Elution of the analytes to the LC system was done with the chromatographic mobile phase. 

One of the best tools for metabolite profiling is the hybrid QTRAP MS/MS system (Applied Biosystems).119-121 While the hybrid QTRAP MS/MS was initially considered a premier tool for metabolite identification, it has more recently been seen as a tool for quantitation and metabolite profiling. Li et al.122 described the use of a hybrid QTRAP MS/MS system for discovery PK assays plus metabolite profiling in the same analytical procedure. Because QTRAP MS/MS may be used as a triple quadrupole MS system, it can be used as part of a quantitative HPLC/MS/MS system. Because QTRAP MS/MS also has linear ion trap capabilities, it can be used for metabolite screening and characterization—essentially it combines the capabilities of a triple quadrupole mass spectrometer and a linear ion trap mass spectrometer. 

Analytical data generated in a testing laboratory are generally used for development, release, stability, or pharmacokinetic studies. Regardless of what the data are required for, the analytical method must be able to provide reliable data. Method validation (Chapter 7) is the demonstration that an analytical procedure is suitable for its intended use. During the validation, data are collected to show that the method meets requirements for accuracy, precision, specificity, detection limit, quantitation limit, linearity, range, and robustness. These characteristics are those recommended by the ICH and will be discussed first. 

HPLC is the leading Analytical procedure used for the verification of pharmaceutical cleaning validation programs. HPLC provides a linear, sensitive method for quantitating low levels of residues making the chromatographic finish the most reliable part of the cleaning verification. 

Analytical procedure Accuracy Repeatability Intermediate precision Specificity Detection limit Quantitation limit Linearity Range Compound(s) Reference(s)... 

ISO defines validation as Conformation by examination and provision of objective evidence that the particular requirements for a specified intended use are fulfilled. This is decided by using a number of performance characteristics. These are specificity, linearity, range, accuracy, precision, detection limit (DL), quantitation limit (QL), and robusmess. System suitability testing (SST) is an integral part of many analytical procedures. Definitions of these terms based on the recommendations of the ICH Guideline Q2 (Rl) are given in Table... 

The specified range is normally derived from linearity studies and depends on the intended application of the procedure. This is established by confirming that the analytical procedure provides an acceptable degree of linearity, accuracy, and precision within the extremes of the specified range. 

Wahl et al.15 suggest an analytic procedure similar to analytic Hartree-Fock methods whereby each molecular orbital is expanded as a linear combination of some simple basis functions over which all the one- and two-electron integrals can be efficiently calculated. We have... 

We find that the eg distortions derived from the Ham quenching and the intensity distribution in the progression differ by less than ten per cent, thus confirming the soundness of our analytical procedure. In order to get the actual displacements in Cr-X bond lengths, A(Cr-X)e j and A(Cr-X)ax, for the equilibrium geometry of the luminescent T2 state, the AQ values have to be linearly transformed (17). For the > component of T2g the values in the last two columns of Table II are obtained. The result for the Cs2NaYClg lattice is visualized in Figure 7. 

Check it out. Linear algebra texts describe an analytical procedure using determinants, but computational chemistry employs a numerical iterative procedure called Jacobi matrix diagonalization, or some related method, in which the off-diagonal elements are made to approach zero. 

An analytical procedure for the determination of ciprofloxacin in serum without previous extraction has been developed by Djurdjevic et al. [11]. The determination was carried out at pH 3, using iron(III) nitrate as the chromogenic agent with the addition of sodium dodecyl sulfate. Absorbance values were measured at 430 nm. The linearity range was between 0.5 and 20pg/mL, with a detection limit of 0.2pg/mL. 

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