Interfering signals, elimination

Simulations were made for all three frequencies, determining the g-values principally at 94 GHz, and showing transferability of parameters between frequencies. It was demonstrated (from the model compounds) that interfering signals from Mn(II) at 94 GHz could be eliminated using field-swept echo spectra and making use of the different 7) or r2 relaxation times for the components of the spectra. 

Instruments that have burners and require nebulisation of dilute aqueous sample solutions generally have low background noise in the signal. With graphite furnaces, incomplete atomisation of the solid sample at elevated temperatures can produce interfering absorptions. This matrix effect does not exist in an isolated state and thus cannot be eliminated by comparison with a reference beam. This is notably the case for solutions containing particles in suspension, ions that cannot be readily reduced and organic molecules, all of which create a constant absorbance in the interval covered by the monochromator. 

Most of these potential sources of error have actually been eliminated, or at least minimized, in commercial analyzers by proper hardware and software implementation, e.g., proper washing and cleansing procedures, signal stability criteria, corrections of the residual potential or simply by declaring limits , i.e., the types of sample, interfering substances, vial types to be avoided, by limiting the number of reports per hour, adjusting within-day and between-day imprecision and the lifetime of the electrodes. 

By using well-selected matrix modifiers, background signals may be reduced, or even eliminated, before the atomization step takes place. Modifiers can be used in two different ways they either facilitates the vaporization of the interfering... 

Disposable cuvettes are used only once to eliminate the possibility of lysozyme carryover. All microcentrifuge tubes and pipette tips are autoclaved, and buffers and BSA solutions are not used beyond 7 days. The M. lysodeikticus suspension is prepared 18-24 hr before use and set at 37° with shaking, to hydrate fully. It was found that substrate prepared just before use settled much faster and interfered with the signal at the low concentrations of enzyme used. 

Homogeneous immunoassay (HOIA) does not require physical separation of the free and antibody-bound antigen because the measured physical signal derived form the antibody-boimd, labeled material may be significantly different from that of the unbound entity. There may be an enhancement or an inhibition of enzyme activity upon binding of the antibody to the antigen. HOIA are simple to perform and automation can be carried out easily. Elimination of the separation step avoids a major source of imprecision in the assay. However selectivity may be compromised since interfering substances are not eliminated in the separation step. 

The application of chromatographic or electrophoretic systems leads to the separation of not only several substrates but also of sample constituents, which could infiuence the enzyme activity or lead to enz5rme-independent signals [75]. An alternative approach to eliminate these interferences is the restriction of the access of interfering compoimds to the enzyme and the transducer. This can be achieved by adapting the... 

The reflectometric evaluation procedure of the Ektachem system differs considerably from that of other dry chemistry systems. Ulbricht s sphere is not required in this reflectometric measurement. Measurement is effected from the underside of the slides. The arrangement of the measurement makes it possible to eliminate interfering substances that can influence the reflectometric measurement signal by their colour only. 

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