Multielement speed

ICP-OES is one of the most successful multielement analysis techniques for materials characterization. While precision and interference effects are generally best when solutions are analyzed, a number of techniques allow the direct analysis of solids. The strengths of ICP-OES include speed, relatively small interference effects, low detection limits, and applicability to a wide variety of materials. Improvements are expected in sample-introduction techniques, spectrometers that detect simultaneously the entire ultraviolet—visible spectrum with high resolution, and in the development of intelligent instruments to further improve analysis reliability. ICPMS vigorously competes with ICP-OES, particularly when low detection limits are required. 

Chapters 7 and 8 describe two major techniques for the monitoring of trace elements in environmental samples atomic absorption (AA) and inductively coupled plasma-atomic emission spectroscopy (ICP). AA is most ideally suited for analyses where a limited number of trace metal concentrations are needed with high accuracy and precision. ICP has the advantage of multielement analysis with high speed. 

The FAAS method offers similar detection limits to NAA and is suitable for the determination of low levels of lead. Equipment costs are reasonable and the instrumentation is commonplace in many analytical laboratories. A large number of metallic elements, over a wide concentration range, extending down to ultra-trace level, can be analyzed, thus making the technique versatile and useful for other forensic applications as well as FDR detection. Apart from cost, the main advantages are simplicity, speed of analysis, and in house operation. One disadvantage of FAAS is that it is not capable of simultaneous multielement analysis. 

Another factor which influences the speed in performing an analysis is calibration of the instrument. Calibration is especially time-consuming in cases where different elements are run on every analysis but even in cases where the same elements are determined time after time, the frequency of instrument calibration required to maintain a desired level of accuracy is an important consideration. Since manual data collection is not feasible in multielement determinations, the ideal system would undoubtedly be computerized. The computer would handle all data collection steps, the construction of calibration curves by mathematical curve-fitting methods, and the calculation of concentrations from these curves. 

Other reports deal with individual elements, such as Ni [1, 86, 87] or Fe [11,84]. The efficiency [71—73] of flame methods (AAS) has been compared with flameless techniques (NFAAS) (Table 6). Because of their significance there have been attempts to determine the elements P [38] and S [78] directly with AAS. This, however, requires a device which can measure ultraviolet lines (ca. 180 nm) with sufficient sensitivity. Good results can also be achieved by gas chromatographic separation and successive AAS determination [92] and simultaneous multielement analysis with a Vidicon-detector has been tried [68] because the speed with which the information is gained can be very important in practice. Some work [39, 53] reports on the problem of molecular bands which can appear when working with... 

EUTRON ACTIVATION ANALYSIS IS A VERY SENSITIVE TECHNIQUE for trace element determinations in various samples. If there are no elements that mutually interfere, the purely instrumental version of this method is often chosen for its established advantages such as accuracy, speed, sensitivity, simultaneous multielement determination, and sample preservation (1). For these reasons, instrumental neutron activation analysis (INAA) was applied to samples taken from a series of metal-working residues excavated at Tel Dan, Israel, from 1985 to 1986. 

Thus [Cu] was thus calculated to be 11.3 ppm for this orchard leaf sample which was NBS certified as 12 ppm. The sampling procedure required only a few seconds for each of the measurements, and only three scans or less are needed for this type of procedure. Precision is typically of the order of +0.5% and combined with the system s speed the technique is obviously suitable for multielement quantitative determinations, and those applications requiring high sample throughput. 

The most common type of emissions spectrometer used today is of the multielement type. This type of instrument has the speed advantage that the plant chemist wants as opposed to a sequential type of spectrophotometer. A multielement type can measure up to 60 elements at a time. When an arc or spark type of instrument is used, it is necessary to integrate and average the signal produced to obtain reproducible line intensities. 

The advent of inexpensive computing power has changed dramatically the way voltammetric determinations are performed. In particular, automated multielement determination schemes and high speed flow systems are now available for convenient and effective trace metal determination in biological samples. 

One of the main attractions of ICPMS lies with the lower detection limits attainable with mass spcclromct-ric detection than with optical detection. These limits in many cases equal and sometimes exceed those that can be realized by electrothermal atomic absorption methods. The ICPMS procedure, of course, offers the great advantages of speed and multielement capability. 

X-ray fluorescence offers a number of impressive advantages. The spectra are relatively simple, so. spectral line interference is minimal. Generally, the X-ray mcthixl is nondestructive and can be used for the analysis of paintings, archaeological specimens, jewelry, coins, and other valuable objects without harm to the sample. Furthermore, analyses can be performed on samples ranging from a barely visible speck to a massive object. Other advantages include the speed and convenience of the procedure, which permit multielement analyses to be completed in a few minutes. Finally, the accuracy and precision of X-ray Huorcscence methods often equal or exceed those of other methods. ... 

A set of DC-RF voltage on the rods will steer the analyte ions of interest electrostatically through the center of the quadrupole mass filter until the exit and they will be converted to an electrical pulse by the detector while other ions of different mass-to-charge ratios will stop in the quadrupole. In a multielemental analysis, the mass scan process is repeated one after another for all analyte ions of different mass-to-charge ratio until all the analytes in a multielement analysis have been measured. Quadrupole scan rates are typically on the order of 2,500 atomic mass units (amu) per second and can cover the entire mass range of 0-300 amu in about 0.1 s. However, real-world analysis speeds are much slower than the above. 

Due to the tendency of microelectronic devices to reduce their sizes it is necessary to take into account the peculiarities of sohd-state reactions between Ni nanofilms and siheon substrate. Industrial implementation of metaUic silicides requires the reduction of contact layers and resistance of source/sink transitions while producing high-speed multielement integrated microcircuits. This is the NiSi that is most frequently used in manufacture of CMOS (Complementary... 

Although most instruments offer cool plasma capability, there are subtle differences in the way it is implemented. It is therefore very important to evaluate the ease of setup and how easy it is to switch from cool to normal plasma conditions and back in an automated multielement run. Also, remember that there will be an equilibrium time in switching from normal to cool plasma conditions. Make sure you know what this is, because an equivalent read-delay will have to be built into the method, which could be an issue if speed of analysis is important to you. If in doubt, set up a test to determine the equilibrium time by carrying out a short stability run while switching back and forth between normal and cool plasma conditions. 

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