Reproducibility and robustness

Precision measures how close data points are to each other for a number of measurements under the same experimental conditions. According to the ICH, precision is made up of three components repeatability, intermediate precision, and reproducibility. The term ruggedness, which has been used in the USP, incorporates intermediate precision, reproducibility, and robustness. 

The main drawback in chiral separation methods using derivatized CDs is that these selectors are mainly available as complex mixtures that contain a large number of isomers differing in their degree of substitution, which may result in batch-to-batch selectivity differences.The use of pure single enantiomers or very reproducible mixtures is thus required to obtain reproducible and robust methods. 

CE has recently emerged as a powerful tool in carbohydrate analysis with enhanced resolution for isobaric isomers, shorter analysis times, and high sensitivity with EIE detection, as well as better assay reproducibility and robustness over the traditional methods. 

Several successful attempts were done to transfer classical CEIA to a microchip-based format. This kind of miniaturization is a trend that can overcome the limitations of CE in high-throughput systems. On-chip CE offers both parallel analysis of samples and short separation times. Koutny et al. showed the use of an immunoassay on-chip (32). In this competitive approach fluorescein-labeled cortisol was used to detect unlabeled cortisol spiked to serum (Fig. 8). The system showed good reproducibility and robustness even in this problematic kind of sample matrix. Using serum cortisol standards calibration and quantification is possible in a working range of clinical interest. This example demonstrated that microchip electrophoretic systems are analytical devices suitable for immunological assays that can compete with common techniques. 

Protein microarrays have many potential applications in high-throughput analysis of protein function. However, simple, reproducible, and robust methods for array fabrication are required. Here we discuss the background to different routes to array fabrication and describe in detail one approach in which the purification and immobilization procedures are combined into a single step, dramatically simplifying the array fabrication process. We illustrate this approach by reference to the creation of an array of p53 variants, and discuss methods for assay and data analysis on such arrays. 

Determination of Nerve Agents In contrast to those rather unusual methods, GC coupled to diverse detection systems, e.g. flame ionization detector (FID), nitrogen-phosphorus detector (NPD), flame photometric detector or mass spectrometer, as well as liquid chromatographic (LC) methods, represent the most common techniques for OP determination especially for biological samples. These methods offer high resolution, sufficient limits of detection, good reproducibility, and robust hardware devices. For more detailed information readers are referred to recent review articles (Hooijschuur et al, 2002 John et al, 2008). 

A quick search in the PubMed database shows that the number of scientific publications in the microarray area grew exponentially since its introduction in 1995 and remained at 7000 in recent years. Despite its revolutionary growth in the research area, the microarray technique has been slow in penetration in the molecular diagnostic market, as it accounted for only 10% of the whole molecular diagnostic market in 2010 (7). The rather serious concerns about the reproducibility and robustness of microarray data, discussed previously, deterred receiving regulatory approval as well as obtaining success in... 

These techniques will enable the analytical scientist to demonstrate control of the analytical method and provide the necessary selectivity, speed, reproducibility, and robustness. 

As illustrated by several examples, experimental design methods proved to be very useful in the development of reproducible and robust CE methods for the analysis of related substances in drugs. This includes the analysis of complex mixtures of substances isolated from natural sources and the simultaneous separation of chiral and achiral impurities as well as compounds with multiple... 

The regulatory thresholds set by the European Economic Community (EEC), the World Health Organization (WHO) and the Environmental Protection Agency (EPA) for drinking water and water to be treated for drinking requires sensitive, reproducible, and robust analytical methods. 

A two-tier approach is often utilized by residue control laboratories whereby samples are first screened to identify the suspected positive (non-compliant) samples, which are subject to further quantitative and confirmatory analysis. Screening methods should be inexpensive and rapid and permit a high sample throughput. The basic criteria that should be met are a detection capability below the RL, a low incidence of false-negative (compliant) results (<5%), and a high degree of repeatability, reproducibility, and robustness. A low incidence of false-positive results is also important to reduce the costs incurred by additional confirmatory analysis. False-positive results in screening analysis can occur for a number of reasons, such as if the test is sensitive to other structurally related compounds naturally present in the matrix or to co-contaminants. 

The column is often called the heart of the HPLC separation process, and the availability of stable, high performance stationary phases and columns is critical to the development of mgged, reproducible and robust methods. Modem commercial columns can differ widely among suppliers and these differences can sometimes affect the development process of the desired HPLC method. Specifically, different columns can vary in terms of plate numbers (Af), retention characteristics (X) and resolution (i s). For these reasons, column and stationary phase manufactures have developed technologies to help ensure that these separation materials are produced in a more consistent and reproducible maimer. An excellent reference by Snyder etal. [1] provides a comprehensive overview of modem stationary phases and column technology. 

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