Robustness of method

Robustness of methods based on broad-on-nar row approach (one of narrow standar ds is used as broad standard for correction of calibration function) is higher but some disadvantages also are observed. 

In this work there is proposed approach which allows using broad standar ds for calibration and system suitability test. The approach is based on main principle of using of standards i.e. maximal closeness of tested sample and standar d. It has been shoved that the approach allows achieving essential improvement of robustness of method for determination of MWD of dextrans. 

Crops with high acid content have to be tested separately, to demonstrate the robustness of methods with regard to changes in pH. In such cases, where extractions are performed at pH values which are lower than those of acidic crops (e.g., <3), the influence of sample acidity is not significant. It is assumed that under such circumstances an expert statement should be sufficient and may replace validation experiments with representative commodities of this matrix group. 

Advantages of this technique are the efficiency of development of methods, structured development profiles, and effective reporting of what was performed during the different method development iterations. In addition, it is possible to model the effect of parameter variation on the robustness of methods in addition to general chromatographic figures of merit apparent efficiency, tailing, resolution of critical pairs, backpressure of system, total run time. 

The conductor-like screening model (COSMO) is a continuum method designed to be fast and robust. This method uses a simpler, more approximate equation for the electrostatic interaction between the solvent and solute. Line the SMx methods, it is based on a solvent accessible surface. Because of this, COSMO calculations require less CPU time than PCM calculations and are less likely to fail to converge. COSMO can be used with a variety of semiempirical, ah initio, and DFT methods. There is also some loss of accuracy as a result of this approximation. 

Q-Chem also has a number of methods for electronic excited-state calculations, such as CIS, RPA, XCIS, and CIS(D). It also includes attachment-detachment analysis of excited-state wave functions. The program was robust for both single point and geometry optimized excited-state calculations that we tried. 

If uneontrolled, temperature ean have a signifieant effeet on reprodueibility and the robustness of separations. This ean eause major problems in metlrod transferability between laboratories and at its worst ean require a method to be reoptimised or revalidated. Most separations therefore require a tlrermostated environment. However, the important faetor is tire temperature witlrin the eolumn bed, not just the sunounding enelosure. Cireulating ah ovens, statie air ovens, metal bloek heaters and eireulating water baths ean all generate different effeetive temperatures even if set to the same nominal values. 

NEW APPROACH TO INCREASING OF ROBUSTNESS FOR METHOD OF DETERMINATION OF MOLECULAR WEIGHT DISTRIBUTION IN DEXTRANS... 

The main problem of determination of molecular weight distribution (MWD) of dextrans (polysachaiides which ai e used as active substances for infusion medicines) is low robustness of the existing method. It means that obtained results are strongly dependent on controlled and uncontrolled pai ameters of chromatographic system standai d substances for calibration loading on columns etc. It has been shoved on practical examples. 

The robustness of an analytical procedure is a measure of its capacity to remain unaffected by small, but deliberate, variations in method parameters this provides an indication of its reliability during normal usage. 

Municipal solid waste incinerators (MSWIs) are a robust treatment method for very different mixed waste types of different origin. The typical MSWI handles waste of a calorific value between 9 and 13 MJ/kg. They are the key technology for the treatment of integral household waste in countries such as Denmark, Sweden, the Netherlands and Germany. Some 7% of this integral household waste consists of plastics. Treatment of... 

An extensive introduction into robust statistical methods is given in Ref. 134 a discussion of non-linear robust regression is found in Ref. 135. An example is worked in Section 3.4. 

Expert opinion is a source, frequently elicited by survey, that is used to obtain information where no or few data are available. For example, in our experience with a multicountry evaluation of health care resource utilization in atrial fibrillation, very few country-specific published data were available on this subject. Thus the decision-analytic model was supplemented with data from a physician expert panel survey to determine initial management approach (rate control vs. cardioversion) first-, second-, and third-line agents doses and durations of therapy type and frequency of studies that would be performed to initiate and monitor therapy type and frequency of adverse events, by body system and the resources used to manage them place of treatment and adverse consequences of lack of atrial fibrillation control and cost of these consequences, for example, stroke, congestive heart failure. This method may also be used in testing the robustness of the analysis [30]. 

Volume 18 Signal Treatment and Signal Analysis in NMR, edited by D.N. Rutledge Volume 19 Robustness of Analytical Chemical Methods and Pharmaceutical Technological Products, edited by M.W.B. Hendriks, J.H. de Boer and A.K. Smilde Volume 20A Handbook of Chemometrics and Qualimetrics Part A, by D.L. Massart, B.G.M. 

It should be noted that all requirements listed in Table 10 apply to an individual analyte-matrix combination. There are no specific demands or proposals for investigations of the infiuence of various sample materials. This procedure does propose the study of other matrices together with further parameters infiuencing robustness of the method. 

The development of a robust analytical method is a complex issue. The residue analyst has available a vast array of techniques to assist in this task, but there are a number of basic rules that should be followed to produce a reliable method. The intention of this article is to provide the analyst with ideas from which a method can be constructed by considering each major component of the analytical method (sample preparation, extraction, sample cleanup, and the determinative step), and to suggest modern techniques that can be used to develop an effective and efficient overall approach. The latter portion emphasizes mass spectrometry (MS) since the current trend for pesticide residue methods is leading to MS becoming the method of choice for simultaneous quantitation and confirmation. This article also serves to update previous publications on similar topics by the authors. ... 

All aspects in the analytical process are equally important, and each step should be isolated in method development experiments and/or validation to ensure acceptable quality of results. A good way to evaluate robustness of a method is to alter parameters (e.g., solvent volumes, temperature, pH, sources of reagents) of each step to determine... 

In order to improve the convergence characteristics and robustness of the Gauss-Newton method, Levenberg in 1944 and later Marquardt (1963) proposed to modify the normal equations by adding a small positive number, y2, to the diagonal elements of A. Namely, at each iteration the increment in the parameter vector is obtained by solving the following equation... 

For models described by a set of ordinary differential equations there are a few modifications we may consider implementing that enhance the performance (robustness) of the Gauss-Newton method. The issues that one needs to address more carefully are (i) numerical instability during the integration of the state and sensitivity equations, (ii) ways to enlarge the region of convergence. 

Since most drug discovery projects deal with very sparingly soluble compounds, the usual CE sample concentration would lead to precipitation. The handling of real dmg candidate molecules is poorly developed in CE applications, in comparison to the most robust potentiometric method. 

A recent study published by Badema et al. in 2011 describes a combined method to investigate the toxicity of an industrial landfill s leachate which is based on a triad approach including chemical analyses, risk assessment, and in vitro assays [17]. Moreover, to verify the applicability and the robustness of the proposed method, the approach was applied on a real case study a controlled, ISO-14001 certified landfill for nonhazardous industrial waste and residual waste from the treatment of MSW in northern Italy for which data on the presence of leachate contaminants are available from the last 11 years. 

Consequently, it was proposed to define (Burns et al. [2005]) Robustness of an analytical procedure is the property that indicates insensitivity against changes of known operational parameters on the results of the method and hence its suitability for its defined purpose and Ruggedness of an analytical procedure is the property that indicates insensitivity against changes of known operational variables and in addition any variations (not discovered in intra-laboratory experiments) which may be revealed by inter-laboratory studies (Burns et al. [2005]). 

Relative robustness will have values between 0 (no robustness) and 1 (ideal robustness). Burns et al. [2005] defines the relative robustness of an analytical procedure as the ratio of the ideal signal for an uninfluenced method compared to the signal for a method subject to known operational parameters determined in an intra-laboratory experiment (Burns et al. [2005]). 

Hendricks MMWB, de Boer AH, Smilde AK (1996) Robustness of analytical chemical methods and pharmaceutical technological products. Elsevier, Amsterdam... 

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