Precision selectivity

Assuming maximum corrosion resistance is required, then an anticorrosive primer will be needed, with best protection coming from a crosslinked epoxy stoving primer. Most other properties are dominated by the finish, which will be based on a high molecular weight-polymer, either linear or (more usually) crosslinked. The precise selection of the polymer depends on the balance of properties required, but will be constrained by the type and rate of curing necessary. 

The use of formation and decay rates as measured parameters results in improved precision, selectivity, and throughout, which facilitates application to routine analyses. 

A simple and rapid RP-HPLC method was developed for the determination of retinoid in galenicals. Commercial preparations were diluted, filered and used for separation. Measurements were carried out in an ODS column (150 X 4.6 mm i.d. particle size 3 /xm). Solvents A and B were methanol-10 mM ammonium acetate (75 25, v/v) and methanol-THF (84 16, v/v), respectively. The flow rate was 0.8ml/min. Gradient conditions were 0-25 min, 0 per cent B 35 min, 100 per cent B, isocratic for 10 min. Typical chromatograms are shown in Fig. 2.37. The repeatability of peak area ranged between 0.48 -3.2 per cent for UV-DAD and 0.57 - 3.1 per cent for fluorescence detection. The reproducibility varied between 0.26 - 4.6 per cent. It was found that the method is precise, selective, sensitive and linear, therefore, it can be employed for the routine quality control of this class of drags [85],... 

The USP 24 General Notices state that alternative methods may be used to determine that products comply with the pharmacopoeial standards for the advantages in accuracy, sensitivity, precision, selectivity, adaptability to automation or computerized data reduction, or any other special circumstances. Such alternative or automated methods shall be validated However, when disputed, the compendial method is conclusive as it is the official or referee test. In addition, USP Chapter (61) Microbial Limit Tests states that automated methods may be substituted provided they are validated and give equivalent or better results, whereas USP Chapter (71) Sterility Tests states that alternative procedures may be employed to demonstrate that an article is sterile, provided the results obtained are at least of equivalent reliability. 

The fundamental parameters for bioanalytical validations include accuracy, precision, selectivity, sensitivity, reproducibility, stability of the drug in the matrix under study storage conditions, range, recovery, and response function (see Section 8.2.1). These parameters are also applicable to microbiological and ligand-binding assays. However, these assays possess some unique characteristics that should be considered during method validation, such as selectivity and quantification issues. 

As in traditional methods that use univariate calibrations, the description of a method of analysis that uses multivariate calibration must also include the corresponding estimated figures of merit, including accuracy (trueness and precision), selectivity, sensitivity, linearity, limit of detection (LOD), limit of quantification (LOQ) and robustness. In this chapter, only the most common figures of merit are described. For a more extensive review, see [55]. Also, for a practical calculation of figures of merit in an atomic spectroscopic application, see [12]. 

As shown in this review, precisely selective processes are brought about on the uniform sites. These results arouse the hope that effective catalysts with desired selectivity can be prepared by designing active sites on solid surfaces that fulfill the prerequisites for a given reaction. 

All the six cases very clearly indicate that homeopathic potencies can cure or ameliorate very serious cases in a relatively short time provided the selection of the remedy is right. One can note here very precise selection of a single remedy for an ailment. 

Bio analytical Methodology Bioanalytical methods for BA and BE studies should be accurate, precise, selective, sensitive, and reproducible. A separate FDA guidance entitled Bioanalytical Method Validation (May 2001) is available to assist sponsors in validating bioanalytical methods. 

The fundamental parameters for this validation include accuracy, precision, selectivity, sensitivity, reproducibility, and stability [58], Other parameters are limits of detection (LODs) and quantification (LOQs), linear dynamic range (LDR) [56], In the case of LC-MS/MS based procedures, appropriate steps should be taken to ensure the lack of matrix effects throughout the application of the method, as outlined by several authors [55, 60-64]. 

Before assessing the other validation parameters (trueness, recovery, precision, selectivity, specificity, detection capability, stability, and applicability/mgged-ness), the appropriateness of the calibration model should be evaluated. The correctness of the analytical determination of elements in food and food products depends indeed on the choice and the evaluation of the calibration model. The calibration model gives the mathematical relationship between the signal of the measuring system and the concentration in the sample. Several authors have published guidelines concerning calibration in analytical chemistry [5-7]. 

Parameters usually examined in the validation process are limit of detection, limit of quantitation, bias, precision, selectivity, linearity, range and ruggedness. Limits will be set for each relevant parameter, and if these are achieved during the performance tests the results are documented and the method is said to be fit for purpose and now is a validated method for a given scope (see Section 2.3). 

NPC is ideally suited for the analysis of compounds prone to hydrolysis because it employs nonaqueous solvents for the modulation of retention. An example of the use of NPC in the analysis of a hydrolysable analyte was demonstrated by Chevalier et al. [28] for quality control of the production of benorylate, an ester of aspirin. A major issue in benorylate production is the potential formation of impurities suspected of causing allergic side effects therefore monitoring of this step is critical to quality control. The presence of acetylsalicylic anhydride prohibited the use of RPLC since it can be easily hydrolyzed in the water-containing mobile phase. However, an analytical method based on the use of normal-phase chromatography with alkylnitrile-bonded silica as the stationary phase provided an ideal solution to the analysis. Optimal selectivity was achieved with a ternary solvent system hexane-dichloromethane-methanol, containing 0.2 v/v% of acetic acid to prevent the ionization of acidic function and to deactivate the residual silanols. The method was validated and determined to be reproducible based on precision, selectivity, and repeatability. 

Criteria compounds, matrix, detection limit, precision, selectivity, accuracy, concentration range, qualitative or quantitative, fiu oughput, regulatory day requirements, e.g., 21 CFR Part 11 (6). 

The USP 24 General Notices states that alternative methods may be used to determine that products comply with the pharmacopeial standards for advantages in accuracy, sensitivity, precision, selectivity, and adaptability to automation or computerized data reduction... 

Another recent innovation deals with the chemistry of the capillary wall. For example, capillaries have been improved by coating their inner surfaces with novel chemistries, or by adding a replaceable dynamic coating solution, allowing better resolution of analytes (109-114). Carrier solutions or background electrolytes can be enriched with a variety of additives, permitting the separation of closely related substances at baseline resolution (see Refs. 115-118 and Sec. II). These improvements have lead to better precision, selectivity, and accuracy of separated analytes. Precision and accuracy is improved for both peak migration and peak area counts for the simple and complex analytes. 

A 5—500 pi aliquot of the aqueous sample is precisely selected (Fig. 1.3a) and introduced into the flow manifold. This is especially relevant for the analysis of biological fluids, cell tissues, blood sera, dew and other volume-limited samples, as well as for in vivo assays. Moreover, sampling strategies relying on mini-probes become more practical. In spite of the low sample volume, reliable results are obtained even for very low analyte concentrations. 

Method Approx. Range (mol/L) Approx. Precision (%) Selectivity Speed Cost Principal Uses... 

The recent developments of COX-2 specific NSAIDs has remarkably reduced and almost eliminated the plethora of side effects intimately associated with the traditional NSAIDs. In fact, several natural products have been duly isolated, purified, and identified as precisely selective COX-2 inhibitors. Now, with the availability of COX-2 based NSAIDs in the market, it has become rather important to strike a bonafide comparison of CADD methods for determining the relative binding affinities of COX-2 inhibitors. 

The availability of an accurate, precise, and specific bioanalytical technique for the quantification of active drug moieties in plasma, hlood, or other hiological fluids is an essential prerequisite for the evaluation of the relationship between dose, concentration, and effect of hiotech drugs. In analogy to small molecules, these analytical techniques have to he validated and have to meet prespecified criteria regarding accuracy, precision, selectivity, sensitivity, reproducihihty, and stahihty, for example, those recommended hy the US Food and Drug Administration [10-12]. Additional requirements for bioanalytical method validation for macromolecules have recently been published [11]. 

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