Detection resolution

The array system is discussed in Chapter 29. With array detection, resolution of m/z values depends both on the analyzer and the collector. Historically, the method for recording ions dispersed in space was to use a photographic plate, which was placed in the focal plane such that all ions struck the photographic plate simultaneously but at different positions along the plate, depending on m/z value. This method of detection is now rarely used because of the inconvenience of having to develop a photographic plate. 

As compared to GC, pSFC possesses inferior figures of merit (efficiency, speed, sensitivity, detection, resolution), but allows a greater sample capacity and is more widely applicable. pSFC can be used as an orthogonal separation technique to verify the accuracy of GC methods. pSFC should be thought of as an extension of LC because of similarities in equipment and approach. The... 

Results should be presented in a way that makes them usable by other investigators. Data are best presented in well-organized tables (section 6.1), along with relevant technical data, such as who measured each parameter, measuring error, limit of detection, resolution, results of duplicate and triplicate measurements, and measuring methods applied. A major part of data tables may be included in the appendices of a report. 

Figure 7. Fluorescence decays of a-type bands in the vlh = 1380 cm-1 spectrum of anthracene. The shifts of the bands from the excitation energy are given in the figure. Since these bands are relatively isolated spectrally, low detection resolution was used to maximize the signal. From top to bottom R = 24,16, and S A.

Ideal for high magnification because of its excellent detection resolution for protein labeling. 

Detection resolution measures the degree to which the label localizes to the P antibody site in the cell. The highest detection resolution occurs when the label is bound directly to the 1° antibody. Direct immunocytochemistry with fluorescent label uses no antibodies or molecules to bridge the label to the D antibody. Graphically, the highest detection resolution occurs with the label attached directly to the 1° antibody (Fig. 9.1a, arrow). 

Low resolution occurs when enzymes (i.e., HRP), localized in the microscope generate a reaction product that spreads from the site of the enzyme and decreases the detection resolution. An example of lowest detection resolution would be ABC immunocytochemistry, because an enzyme is the label and it is bridged to the primary antibody by avidin-biotin (Fig. 9.1a, number 2, Low resolution). Any additional molecules that bind to the 1° antibody and bridge the label away from the 1° antibody will decrease the detection resolution. In planning experiments, resolution is important when antigens are localized to a discrete location. 

To help evaluate possible labels and methods, use Table 9.1. Note that the number ratings in Table 9.1 are based on the author s experience and should only be used to compare methods within this table. Detection resolution is the ability to localize the label to the exact site of the primary antibody. The direct immunocytochemistry method does this and is rated as a detection resolution of 10 (Table 9.1, Fig. 9.1a, arrow). With detection methods that have lower detection resolution the number decreases (Table 9.1, Fig. 9.1a, numbers). 

Table 9.1 Detection sensitivity and detection resolution of application methods...

Application method Label types Detection resolution Detection sensitivity Number of incubation steps ... 

Detection sensitivity and detection resolution are measured on a 1-10 scale, with 10 being best and 1 worst... 

In another example, if the goal is to locate neuronal cell bodies containing a specific neurotransmitter, a high detection sensitivity and low detection resolution method would allow the label to diffuse throughout the entire cell. Then the location of specific neurotransmitter molecules within the cell is not important rather location of a cell that contains neurotransmitter is important. The bottom line is to assess the importance of detection resolution and detection sensitivity in selecting a detection method. 

What detection resolution is needed Consider the experiment and the need for localization of label to a specific organelle, nucleus, or cell. For localization to a vesicle, methods with detection resolutions of seven or higher will be needed, while localization to a cell could use detection resolutions as low as 1. A method with low or poor detection resolution results in a label that covers a larger area than the location of the 1° antibody. With high detection resolution, the label approaches the size of the 1° antibody. There is an inverse relationship between the detection resolution and the detection sensitivity. A method with high detection resolution will have low detection sensitivity. 

Detection resolution - a measure of the degree to which the label localizes to the 1° antibody site in the cell. 

Resolution for detecting adjacent elements can be improved, if (1) heavy particles are used (2) detection angles are chosen to be close to 180°, and (3) bombarding energy Eq is sufficiently high. The detection resolution is, however reduced for heavier projectiles e.g., if M = 180 and M = 190 are to be distinguished under the same experimental conditions, the FWHM for a-particles should be <0.5%, however with neon projectiles, the FWHM of about 2% is sufficient. 

The above are approximate conditlone. Fine tuning may be required to meet the criteria (detectability, resolution, etc.) specified in the test method. The items in italics are fixed operating conditions and must be used as indicated. 

Detection, resolution and identification of the weak chain-end resonances in the presence of the much larger signals from the polymer backbone, using simple ID- ( H, and and 2D- (HMQC and HMBC) NMR experiments, was a problem. To surmount this problem, they took advantage of the unique NMR characteristics of the phosphorus-containing chain-end structure when compared with the hydrocarbon-based structure of the rest of the polymer. The atoms on the chain end, exhibit / coupling to which has 100% natural abundance and nuclear spin I = 1/2. These couplings can be used to produce a variety of multidimensional triple-resonance 2D- and 3D-NMR... 

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