Specific resolution

Chiral Hplc Columns. There are about 40 commercially available chiral columns which are suitable for analytical and preparative purposes (57). In spite of the large number of commercially available chiral stationary phases, it is difficult and time-consuming to obtain good chiral separation. In order to try a specific resolution meaninghilly, a battery of chiral hplc columns is necessary and this is quite expensive. 

For SEC separations of polymers, column efficiency is better characterized by specific resolution, R,p, and efficiency, T, than by theoretical plate count. Peak resolution, R is calculated according to (7) ... 

A sample independent parameter is the so-called specific resolution, R,p, which can be obtained from the peak resolution by normalizing the values according to the molar masses of the samples used for testing (24) ... 

TABLE 12.4 Specific Resolution (R,p) Calculations for PLgel Mixed Gel Columns... 

Column type Peak variance (o) Calibration slope (D) Specific resolution (R,p)... 

Calculating the Efficiency Required to Achieve a Specific Resolution... 

Another approach to defining the separation capacity of a column is by its peak capacity (the number of peaks than can be resolved at any specific resolution, usually R, i, in a given separation time). For SEC the pe2dc capacity, PCgc, is given approximately by... 

Peedc-to-peak resolution in SEC can be calculated by the ratio of peak separation at the peak maxiaut to the sum of the baseline peak widths. This general definition of resolution is less useful in SEC, where a measure of the ability of the column to separate solutes of different molecular weight is required. For this purposes, we define a new term, the specific resolution factor, R, which relates peak resolution to sample molecular weight, assuming all measurements are made within the linear region of the molecular weight calibration curve, equation (4.41)... 

The concept of "specific resolution" (Rsp) developed by Yau and coworkers (15) reflects the dual influence of efficiency and slope on resolution ... 

For example, a single estimate for total PCB s has been historically collected in the NHATS program. Current advances in chemical analysis protocols now allow for the determination of isomer specific resolution of PCB s. Given the 209 PCB s that are now possible to detect, an adequate evaluation of the data without the use of pattern recognition techniques seems impossible. From a QA/QC perspective, these methods can facilitate the detection of outliers and aid in the interpretation of human chemical residue data. The application of statistical analysis must keep abreast with these advances made in chemisty. To handle the complexity and quantity of such data, the use of more sophisticated statistical analyses is needed. 

On-line size exclusion chromatographic (SEC) analyses were performed with a Waters Model 401 differential refractometer (DR), a Waters Model 480 ultraviolet (UV) variable wavelength spectrophotometer and a Foxboro Miran lA infrared (IR) photometer, equipped with a zinc selenide ultramicro flowcell of 1.5 mm nominal pathlength and 4.5 /xl volume, purchased from the same supplier. A set of ten Mycrostyra-gel (Waters Associates) columns, regenerated by Analytical Sciences Inc. (ASI) and of nominal porosities 100, 500 (two) 10 (two), 10 (three), 10 and lO X, in the order given and a mobile phase flow rate of 1 ml/min was used. The column set had a specific resolution of 19.7 in 1,4-dioxane, as determined by the method of Yau(2). 

Specificity Resolution from most likely impurities Resolution from impurities and excipients... 

This X-band Overhauser DNP technique has also been developed to study proteins and their interactions with site-specific resolution, employing site-directed mutagenesis and spin-labelling methods128 to... 

The above statement has lot of details in reference to what is a SIM The statement starts with method validation (refer to Chapter 9). Next, most methods need to be specific (specificity, resolution of active from related substances, peak purity), reproducible (precision), quantitative (recovery, linearity, LOD, LOQ), and able to monitor a change in chemical, physical, and/or microbiological properties of drug products over time (refer to sections on stability testing and mass balance). 

However, the specific resolution, R p, provides a better basis for characterizing a... 

Yau et al. [15] developed the concept of specific resolution factor, / ,p, that can be used for direct comparison of resolution power of unit length of various columns ... 

Many laboratories have gathered extensive experience in the application of ion chromatography (IC) for the analysis of inorganic and organic anions. Small carboxylate anions. Groups lA and IIA cations, and heavy metal ions have been identified in tobacco and tobacco smoke by this method. Several of these applications have been presented as tobacco journal (250) and tobacco conference [TCRC (2951), TSRC(1273)] papers. At the 1999 TSRC, Perini (20A85) presented a method associated with IC called transition metal IC (TMIC). TMIC can be used for specific resolution and specia-tion of transition metal ions in tobacco and related matrices. Perini showed that TMIC could be used to detect and spe-ciate at least nineteen transition metal ion. 

The specific resolution factor, Rsp in SEC, relates peak separations to sample molecular weight, assuming all measurements are made within the linear region of the molecular weight calibration curve, Eq. (4.30)... 

Resolution in size-exclusion chromatography is a function of both the calibration curve and column performance. To normalize resolution to a molecular-wei t difference of a decade, the specific resolution has been defined as... 

The attributes of a SEC column packing material are listed in Table 2. As indicated, the support must be optimized with respect to specific resolution, efficiency, column pressure, and mechanical, chemical, and thermal stability. Recovery of mass and activity is particularly important in the analysis and purification of biopolymers. It also plays a role in the analysis of nonbiochemical synthetic polymers on silica-based SEC columns. In addition to recovery losses by adsorption, the recovery for both groups of polymers can also be reduced by polymer degradation as a result of, for instance, mechanical shear. 

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