Powders, atomic emission spectroscopy

Recent work by Mikulec et al. [117] has exploited an unusual property of porous silicon and used this material as an explosive matrix for atomic emission spectroscopy. Freshly prepared, hydride-terminated substrates soaked in aqueous solutions of Gd(N03)3 were detonated with mechanical or electrical triggers in a flashy, exothermic reaction not unlike the combustion of black powder (Figure 16.17). The estimated high ( 2000 K) local temperature created by the explosion was employed to generate emission spectra for alkali metals and heavy metals deposited upon the substrates from solution or suspension. Detonation was completed for a range of porous specimens and did not depend upon either the crystalline identity of the precursor or the morphology of the etched material however, oxidized substrates exhibited a lesser propensity to explode. The intensity of the explosion was... 

Many analytical techniques now require very small sample sizes, for example, Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) and ICP-Mass Spectrometry (ICP-MS) methods may utilise only 0.10-0.5 g of powder which must of course be representative of the original sample. Unless the collected sample is small and finely divided, representivity at this small sample size can only be achieved by fine milling the sub-samples of the coarse powder. 

As a double-check, the concentration of boron in aU DSDP samples was redetermined by ICP atomic emission spectroscopy (ICP-AES). The chert samples were ground in a corundum mortar (Diamonite ) to pass a 200 mesh sieve, and were brought into solution following a modified version of the procedure of Nakamura et al (1992). About 200 mg of sample powder was reacted with HF, HNO3 and mannitol in sealed PFA Teflon ... 

Common techniques for the characterization of the electrocatalysts include High Resolution Electron Microscopy (HRTEM), Extended X-ray Absorption Fine Stracture Spectroscopy (EXAFS), Energy Dispersive Spectroscopy (EDS), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), Near Edge X-ray Absorption Spectroscopy (XANES), X-Ray Powder Diffraction (XRPD), Infrared and Raman Spectroscopy (IR, RS). 

Sample introduction into the plasma is a critical part of the analytical process in atomic emission spectroscopy (AES). Since the ICP is the most commonly used source, the sample introduction schemes described below will focus more on it than the other sources mentioned previously. Sample is carried into the plasma at the head of a torch by an inert gas, typically argon, flowing in the centre tube at 0.3-1.5 L min". The sample may be an aerosol, a thermally or spark generated vapour, or a fine powder. Other approaches may also be taken to facilitate the way the analyte reaches the plasma. These procedures include hydride generation and electrothermal vaporization. 

AAS = atomic absorption spectroscopy ATOF-MS = aerosol time-of-flight mass spectrometry 2,6-ndc = 2,6-naphthalenedicarboxylate bdc = 1,4-benzenedicar-boxylate bpdc = 1,3,5-benzenetricarboxylate bpydc = 2,2 -bipyridine-5,5 -dicarboxylate btb = 4,4, 4"-benzene-1,3,5-triylbenzoate btc = 1,3,5-benzenetricarboxylate 3D = three-dimensional dabco = l,4-diaza[2.2.2]bicyclo-octane EDX = energy-dispersive X-ray spectroscopy EXAFS = extended X-ray fine structure Fc = ferrocenyl ICP-AES = inductively coupled plasma atomic emission spectroscopy MOF = metal-organic framework PSD = postsynthetic deprotection PSM = Postsynthetic modification PXRD = Powder X-ray diffraction 1,4-ndc = 1,4-naphthalenedicarboxylate SALE = solvent-assisted linker exchange SBU = secondary building unit ... 

The Atomic emission spectrometry (ICP-AES) results on the solids confirm the chemical purity of Py, Cp, Qz, Cal and Dol samples. The Po sample contains calcium which, after conversion into calcite, gives approximately 10wt% of this mineral. Sid sample contains 10.3 wt% Mn and 1.86 wt% Mg, in agreement with measurements using a Scanning Electron Microscopy coupled to Energy Dispersive X-Ray Spectroscopy (SEM-EDS) analysis again this explains the difference between the measured and theoretical density of the Sid powder. 

Zinc is present in a number of pharmaceuticals, the most important of which is life-sustaining insulin. Many topical preparations contain zinc as the oxide, sulfate, or stearate as an astringent or antipruritic. Some foot powders contain the antifungicidal zinc undecenoate, and zinc pyrithione is used in antidandruff shampoos. After dissolving them in acid, the topical products can be easily analyzed by either atomic emission or atomic absorption spectroscopy (49), since they contain a relatively high concentration of zinc. However, atomic absorption is approximately four orders of magnitude more sensitive than atomic emission for the determination of zinc (Table 2) and offers superior precision for the analysis of injectable insulin (50), where zinc concentrations can be as low as 4 ppm (39). 

Various techniques can be used for quantitative analysis of chemical composition, including (i) optical atomic spectroscopy (atomic absorption, atomic emission, and atomic fluorescence), (ii) X-ray fluorescence spectroscopy, (iii) mass spectrometry, (iv) electrochemistry, and (v) nuclear and radioisotope analysis [41]. Among these, optical atomic spectroscopy, involving atomic absorption (AA) or atomic emission (AE), has been the most widely used for chemical analysis of ceramic powders. It can be used to determine the contents of both major and minor elements, as well as trace elements, because of its high precision and low detection limits. 

See also Atomic Absorption Spectrometry Flame Electrothermal. Atomic Emission Spectrometry Inductively Coupled Plasma. Color Measurement. Forensic Sciences Paints, Varnishes, and Lacquers. Gas Chromatography Pyrolysis. Infrared Spectroscopy Industrial Applications. Liquid Chromatography Size-Exclusion. Paints Water-Based. Spectrophotometry Organic Compounds. X-Ray Absorption and Diffraction X-Ray Diffraction - Powder. X-Ray Fluorescence and Emission Wavelength Dispersive X-Ray Fluorescence Energy Dispersive X-Ray Fluorescence. 

Inductively coupled plasma-atomic emission spectrometry allows the determination of anionic surfactants (LAS and AS) and inorganic compounds (phosphate, silicate, zeolite, sulfate). Other techniques, such as X-ray fluorescence spectroscopy and X-ray powder diffraction, have been used for the qualitative analysis of inorganic detergents. For surface analysis, optical light microscopy, scanning electron microscopy, and transmission electron microscopy characterize particles, deposition of surfactant, or other detergent ingredients on fabric. 

Spectroscopy is the study of the interactions of electromagnetic radiation, or light, with matter in order to gain information about the atoms or bonds present within the system. There are many different types of spectroscopic techniques however, most of the techniques are based on the absorption or emission of photons from the material being studied. The applications of spectroscopy span a variety of disciplines and can allow scientists to, among countless other things, determine the elemental composition of a nearby dwarf star, the chemical identity of an unknown white powder sample, whether a transfected gene has been expressed, or the types of individual bonds within a molecule. 

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