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Subject sample throughput

Unstable radionuclei result on subjecting the nuclei of some elements to neutron bombardment. During the decay process, in which the radionuclei return to more stable forms, characteristic radiation is emitted. The energy of the radiation is characteristic of the element, and its intensity forms the basis for quantitative elemental analysis. The advantages of NAA for trace analysis include low detection limits, good sensitivity, multi-element capability and relative freedom from matrix effects. However, for successful application of this technique skilled personel are required and because of the low sample throughput the amount of work involved in the analysis of column fractions, for example, is prohibitively high. In addition, it may take up to several weeks before the results are available. Further, only few laboratories have easy access to a neutron source. [Pg.166]

In the following pages we first give brief accounts of the developments in microelectronics, computers and data processing which underpin virtually all modem analytical methods. Secondly some novel methods, which indicate the breadth of the subject and the trends towards high sample throughput and/or complexity of analysis will be described. Finally a major specific analytical problem, re-presenative of many likely to be encountered in the foreseeable future will be discussed. In the space available, selectivity and brevity is essential. Our object is to indicate trends, not to be comprehensive. [Pg.4]

Most organic compounds when subjected to infra-red radiation present characteristic absorption bands. The spectral data are compared to those obtained for standard reference wines used to calibrate the instrument. The concentration of the analytes is calculated using multiple linear regression the apparatus is computerised and can be linked to an automatic sampler. The analyte should exhibit strong absorption bands for the method to be exploitable, and it is thus only suitable for major wine or must constituents, essentially ethanol and sugars. The major qualities of this technique are simplicity of operation, high sample throughput and the lack of necessity for sample preparation - the only required sample re-treatment is the removal of carbon dioxide from musts in fermentation. [Pg.664]

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. [Pg.154]

As measurements do not require a heating up procedure of the sample as in TIMS, measurements require about 50% of the time, which increases sample throughput. This is a considerable advantage for studies involving compartmental modeling, taking into account that such studies involve usually 10-20 subjects who generate dozens of samples to be analyzed. [Pg.455]

While the benefits of flow-based methods such as the reduction of the analysis time and higher sample throughput are greatly appreciated in the analytical sciences, their applications in the determination of parabens are greatly limited. For comparison, flow-based techniques are widely applied in the analysis of other preservatives such as sulfites and nitrites [30,31]. Thus, more investigations and publications on this subject are called for. The applications of this technique in the analysis of foodstuffs are limited to simple techniques such as flow injection and sequential injection analysis. However, the use of novel hyphenated flow-based techniques would bring about a breakthrough in the determination of parabens in various consumer products. Moreover, there should be a shift to the use of mass spectrometric detectors from the selective detectors such as chemiluminescence and UV-Vis. [Pg.190]

Capillary gas chromatography allows the analysis of complex mixtures of compounds to be carried out. However, the analysis time per sample is inherently long in order to obtain high resolution of the components, and this limits the throughput of samples. Slurry samples are biotic and therefore subject to continuing changes which are reflected... [Pg.315]

Fig. 4. Illustration of the multiplex allele specific diagnostic assay. At the top of the panel, radioactive ohgonucleotide probes (indicated by stars) are selected by hybridization to amphcons from patient samples affixed to membrane filters. When a putative mutation-bearing allele hybridizes to a radioactive probe, it can be eluted from the filter and subjected to sequencing using chemical or radioactive dideoxy-terminator methods. This permits unequivocal identification of a large number of mutations at a high throughput. Fig. 4. Illustration of the multiplex allele specific diagnostic assay. At the top of the panel, radioactive ohgonucleotide probes (indicated by stars) are selected by hybridization to amphcons from patient samples affixed to membrane filters. When a putative mutation-bearing allele hybridizes to a radioactive probe, it can be eluted from the filter and subjected to sequencing using chemical or radioactive dideoxy-terminator methods. This permits unequivocal identification of a large number of mutations at a high throughput.

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