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Analytical Test Methods for Polymer Characterization
Published in Nicholas P. Cheremisinoff, Elastomer Technology Handbook, 2020
Nicholas P. Cheremisinoff, Boyko Randi, Leidy Laura
In inductively coupled plasma atomic emission spectroscopy (ICP) the sample is vaporized and the element of interest atomized in an extremely high temperature (~7000°C) argon plasma, generated, and maintained by radiofrequency coupling. The atoms collide with energetically excited argon species and emit characteristic atomic and ionic spectra that are detected with a photomultiplier tube. Separation of spectral lines can be accomplished in two ways. In a sequential or scanning ICP (Figure 28), a scanning monochromator with a movable grating is used to bring the light from the wavelength of interest to a single detector. In a simultaneous or direct reader ICP (Figure 29), a polychromator with a diffraction grating is used to disperse the light into its components wavelength. Detectors for the elements of interest are set by the vendor during manufacture. Occasionally a scanning channel is added to a direct reader to allow measurement of an element not included in the main polychromator.
Inductively Coupled Plasma Optical Emission Spectrometry
Published in Grinberg Nelu, Rodriguez Sonia, Ewing’s Analytical Instrumentation Handbook, Fourth Edition, 2019
Both the qualitative and quantitative information about a sample is obtained from the lights or radiations emitted by the excited atoms and ions. Because the excited species in the plasma emit light at more than one wavelength, the emission from the plasma discharge is referred to as polychromatic. The polychromatic radiation has to be sorted out into individual wavelengths so that the emission from each and every atom and ion can be identified and quantified without interferences or overlaps from emission at adjacent wavelengths. The separation of light according to their wavelengths is generally achieved using a monochromator, which is used to measure light one wavelength at a time, or a polychromator, which is used to measure light at more than one wavelength simultaneously. After the separation of the light, the actual detection of the light is done using a photosensitive device such as a photomultiplier tube (PMT) in the old days or more state-of-the-art devices such as photodiode array (PDA), charge coupled device (CCD), and charge injection device (CID) nowadays.
Reclaimed Wastewater Monitoring — Sampling and Analysis
Published in Donald R. Rowe, Isam Mohammed Abdel-Magid, Handbook of Wastewater Reclamation and Reuse, 2020
Donald R. Rowe, Isam Mohammed Abdel-Magid
The elements and metals listed in Table 8.6 and 7 can also be detected by using the inductively coupled plasma (ICP) technique. ICP techniques are applicable over a broad linear range and are quite sensitive for some elements and metals. In general, detection limits for ICP methods are higher than those for the atomic absorption methods.6 However, each element or metal must be considered separately depending upon the sensitivity, detection limit, and optimum concentration range for that element or metal. The ICP technique can be used to determine trace elements in a solution simultaneously, or sequentially for multielement samples.41 The principles involved in the ICP technique are presented in the following excerpt from Standards Methods.6An ICP source consists of a flowing stream of argon gas ionized by an applied radio frequency field typically oscillating at 27.1 MHz. This field is inductively coupled to the ionized gas by a water-cooled coil surrounding a quartz “torch” that supports and confines the plasma. A sample aerosol is generated in an appropriate nebulizer and spray chamber and is carried into the plasma through an injector tube located within the torch. The sample aerosol is injected directly into the ICP, subjecting the constituent atoms to temperatures of about 6000 to 8000 K. Because this results in almost complete dissociation of molecules, significant reduction in chemical interferences is achieved. The high temperature of the plasma excites atomic emission efficiently. Ionization of a high percentage of atoms produces ionic emission spectra. The ICP provides an optically “thin” source that is not subject to self-absorption except at very high concentrations. Thus linear dynamic ranges of four to six orders of magnitude are observed for many elements.The efficient excitation provided by the ICP results in low detection limits for many elements. This, coupled with the extended dynamic range, permits effective multielement determination of metals. The light emitted from the ICP is focused onto the entrance slit of either a monochromator or a polychromator that effects dispersion. A precisely aligned exit slit is used to isolate a portion of the emission spectrum for intensity measurement using a photomulti-plier tube. The monochromator uses a single exit slit/photomultiplier and may use a computer-controlled scanning mechanism to examine emission wavelengths sequentially. The polychromator uses multiple fixed exit slits and corresponding photomultiplier tubes; it simultaneously monitors all configured wavelengths using a computer-controlled readout system. The sequential approach provides greater wavelength selection while the simultaneous approach can provide greater sample throughput.6
Corrosion of mild steel under insulation – the effect of dissolved metal ions
Published in Corrosion Engineering, Science and Technology, 2020
Q. Cao, M. Esmaily, R. L. Liu, N. Birbilis, S. Thomas
Inductively coupled plasma – optical emission spectroscopy (ICP-OES) was used to determine the ionic concentrations of the extracts from the moist insulation. Six identical dry insulation blocks (each with a dimension of 5 × 4 × 2 cm3) were submerged into test bottles filled with solutions with different pH (pH = 3, 5, 7, 9, 11 and 13). These solutions were prepared using RO water with sulphuric acid (H2SO4) and sodium hydroxide (NaOH) for pH adjustment. After 5, 10, 20 and 30 days of immersion, 2 mL of aqueous extracts were collected from each test bottle and then diluted to 14 mL followed by acidification using 5% nitric acid (HNO3) before ICP-OES analysis. The PerkinElmer Avio 200 ICP Optical Emission Spectrometer, under the control of Syngistix software was used for the analysis. Signals were collected by an array of photomultiplier tube detectors, a monochromator (1 m focal length) and polychromator (50 cm focal length Pschen-Rungen type).
Development of Real-Time Software for Thomson Scattering Analysis at NSTX-U
Published in Fusion Science and Technology, 2019
Roman Rozenblat, Egemen Kolemen, Florian M. Laggner, Christopher Freeman, Greg Tchilinguirian, Paul Sichta, Gretchen Zimmer
The real-time hardware can acquire data of eight polychromators, i.e., eight spatial channels. Each polychromator is equipped with up to six spectral filters and associated avalanche photodiodes (APDs) to measure the spectrum of the scattered light. The signals of the APD detectors are digitized with an SIS3316-250–14 analog-to-digital converter (ADC) that operates at 250 Msamples s−1 with 14-bit resolution.15 The ADC is connected to a server via a Solarflare16 Ethernet card. There are four SIS3316 cards with 16 channels each, which allows for the digitization of the eight spatial channels and other required signals for the TS analysis. The cards continuously digitize to a circular buffer, whose readout is triggered by laser pulses. When the cards are triggered, the peak values of the detected pulse are extracted in the first step of the real-time Multi-Pulse Thomson Scattering (MPTS) analysis software. The real-time server that is used to process the TS calculation is a ServeDirect server with 32 Gbytes Memory, Intel Xeon 2.2 GHz with 20 cores. The output of the real-time MPTS server is done through an analog output (AO) 16AO64 PCIE card, which has up to 64 channels with 16-bit resolution.17
Elemental Characterization of Neutron-Irradiated Tungsten Using the GD-OES Technique
Published in Fusion Science and Technology, 2019
Nathan C. Reid, Lauren M. Garrison, Chase N. Taylor, Jean Paul Allain
By sputtering the surface of the sample, ionizing the eroded material, and measuring the optical emission of the excited atoms, GD-OES can measure elemental information in a sample. An emission spectrum from electronic transitions occurring by sputtered atoms in the glow discharge plasma is picked up by the optical elements in a polychromator. Each element is defined by the spectral lines that it produces when in the excited state. Lines are ordered by the type of excitation,aThe number of photons that are emitted is directly proportional to the number of excitations. (Fewer photons are emitted as the order of emission gets larger.) Quantification of the light that is detected by each element-dedicated PMT can be converted from a voltage signal to an elemental concentration. shown in Table I. The polychromator scheme is developed so that no two lines overlap.