Ideal element detector

The ideal high-throughput analytical technique would be efficient in terms of required resources and would be scalable to accommodate an arbitrarily large number of samples. In addition, this scalability would be such that the dependence of the cost of the equipment to perform the experiments would scale in a less than linear manner as a function of the number of samples that could be studied. The only way to accomplish this is to have one or more aspects of the experimental setup utilize an array-based approach. Array detectors are massively multiplexed versions of single-element detectors composed of a rectangular grid of small detectors. The most commonly encountered examples are CCD cameras, which are used to acquire ultraviolet, visible and near-infrared (IR) photons in a parallel manner. Other examples include IR focal plane arrays (FPAs) for the collection of IR photons and channel electron multipliers for the collection of electrons. 

Detecting single nano-objects in a far-held laser spot requires carefully optimized setups, discussed in several reviews and books [3, 19]. Hereafter, we assume ideal conditions, perfect optical elements (detectors, sources, hlters, etc.), to concentrate on the fundamental limitations to signal-to-noise ratio in optical single-molecule studies. We consider three main detection techniques applied to individual small absorbers, emitting or not photoluminescence direct absorption, huorescence and photothermal contrast. 

Their Spectraspan VI that appeared on the market in 1984 appears to be an ideal element selective detector for HPLC, though very few papers have thus far utilized that specific model in HPLC-DCP studies. It is arguable that MDLs via HPLC-DCP must, by the very nature of the DCP, always be Inferior to the HPLC-ICP system. We have not found this always to be the case, and Indeed in a very recent HPLC-DCP study of various chromium containing species, the HPLC-DCP MDLs appeared somewhat better (lower) than those reported by HPLC-ICP methods (22). We have already suggested some possible explanations for these observations, though nobody has yet made a full, direct comparison of HPLC-DCP HPLC-ICP MDLs for even a few metal species. 

TOF-MS (time of flight MS), with its high mass-resolving power is capable of generating mass data of sufficient accuracy and precision to establish the elemental composition of an analyte. The high accuracy, fast response time, and ease of peak deconvolution capability make TOF-MS an ideal online detector to interface with high-resolution separation techniques. The hyphenation of TOF-MS with CE... 

This work is dedicated to an analysis of the possible improvements of the performance of photonic detectors with a goal to use them at room temperature and to approach them as much as possible to the previously described idealized IR detector element. The presentation is limited to photoconductive and photovoltaic intrinsic detectors, although for the most part it can be generalized to any type of... 

Nevertheless, it was clear from the prior literature, especially the work of Uden et al., that the DCP could be an almost ideal element specific detector for various forms of chromatography [22-24]. What has limited its general popularity has been its single source availability, and the fact that there has usually been a single supplier of the instrumentation and replacement parts, at least until very recently. 

The Mattauch-Herzoggeometry (Fig. 3.20) enables detection of several masses simultaneously and is, therefore, ideal for scanning instruments [3.49]. Up to five detectors are adjusted mechanically to locations in the detection plane, and thus to masses of interest. Because of this it is possible to detect, e. g., all isotopes of one element simultaneously in a certain mass range. Also fast, sensitive, and precise measurements of the distributions of different isotopes are feasible. This enables calculation of isotope ratios of small particles visible in the image. The only commercial instrument of this type (Cameca Nanosims 50) uses an ion gun of coaxial optical design, and secondary ion extraction the lateral resolution is 50 nm. 

EC detection is a promising alternative for capillary electrophoresis microchips due to its inherent characteristics, allowing a proper miniaturisation of the devices and compatibility with the fabrication processes, in case of an integrated detection. Moreover, the low cost associated permit the employment of disposable elements. As the EC event occurs on the surface of electrodes and the decrease in size usually results in new advantages (see Chapter 32), the possibilities of incorporating EC detectors are broad. The simplicity of the required instrumentation, portable in many cases, suit well with the scaling-down trend. Moreover, as the sample volume in conventional micro-channel devices is less than 1 nL, a very highly sensitive detector should be constructed to analyse even modest concentrations of sample solutions. Since sensitivity is one of the accepted characteristics of EC detection EC-CE microchips approach to the ideal analytical devices. 

The ideal route would be one in which the pyroelectric detector material is laid down in thin film form by a route compatible with the production of the silicon ROIC. There are obvious parallels with the development of FeRAMS (see Section 5.7.5) and the substantial effort now devoted to their development will have a positive impact on the manufacture of pyroelectric arrays. Challenges he in the requirement to process the deposited films at temperatures not too high for the underlying integrated circuit, and the need to engineer the temperature diffusion characteristics within the element and its surroundings so as to optimise image definition. 

The second major environmental application of FFF has been the use of an element-specific detector, usually in series with a UV detector, to provide elemental composition data along with the PSD. Graphite-furnace atomic absorption spectrometry has been used off-line on fractions collected from the FFF run. However, the multi-element detection, low detection limits and capability to function as an online detector have made inductively coupled plasma mass spectrometry (ICP-MS) the ideal detector for FFE85-86 The sample introduction system of the ICP-MS is able to efficiently transport micron-sized particles into the high-temperature plasma,... 

The use of an atomic emission detector (AED) coupled to a GC may provide under ideal conditions information about the empirical formula of the analyte corresponding to a GC peak. However, it was found that the AED responses of C, Cl and O of a series of phenols is related to the working condition of the AED. The elemental response of Cl is independent of molecular structure, but those of C and O are not, probably due to formation of CO in the plasma. The O response is also affected in nitrophenols, probably due to NO2 formation. A novel detector, based upon hyperthermal negative surface ionization, shows up to 100-fold higher sensitivity than that of the FID for alcohols and phenolic compounds. ... 

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