Liquid samples plasma emission spectroscopy

Atomic absorption spectrometry with flame (AA-F) or electrothermal atomization furnace (AA-ETA), inductively coupled plasma-emission spectroscopy (ICP-ES), inductively coupled plasma-mass spectrometry (ICP-MS), and high-performance liquid chromatography-mass spectrometry (LC-MS) are state-of-the-art analytical techniques used to measure metals in biological fluids. They are specific and sensitive and provide the cfinical laboratory with the capability to measure a broad array of metals at clinically significant concentrations. For example, ICP-MS is used to measure several metals simultaneously. Photometric assays are also available but require large volumes of sample and have limited analytical performance. Spot tests are also... 

Spectrochemical methods Higher yield ion sources for mass spectrometry Hyphenated techniques, gas or liquid chromatogr hy with inductively coupled plasma emission spectroscopy Minimization of sample preparation... 

To examine a sample by inductively coupled plasma mass spectrometry (ICP/MS) or inductively coupled plasma atomic-emission spectroscopy (ICP/AES) the sample must be transported into the flame of a plasma torch. Once in the flame, sample molecules are literally ripped apart to form ions of their constituent elements. These fragmentation and ionization processes are described in Chapters 6 and 14. To introduce samples into the center of the (plasma) flame, they must be transported there as gases, as finely dispersed droplets of a solution, or as fine particulate matter. The various methods of sample introduction are described here in three parts — A, B, and C Chapters 15, 16, and 17 — to cover gases, solutions (liquids), and solids. Some types of sample inlets are multipurpose and can be used with gases and liquids or with liquids and solids, but others have been designed specifically for only one kind of analysis. However, the principles governing the operation of inlet systems fall into a small number of categories. This chapter discusses specifically substances that are normally liquids at ambient temperatures. This sort of inlet is the commonest in analytical work. 

In Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), a gaseous, solid (as fine particles), or liquid (as an aerosol) sample is directed into the center of a gaseous plasma. The sample is vaporized, atomized, and partially ionized in the plasma. Atoms and ions are excited and emit light at characteristic wavelengths in the ultraviolet or visible region of the spectrum. The emission line intensities are proportional to the concentration of each element in the sample. A grating spectrometer is used for either simultaneous or sequential multielement analysis. The concentration of each element is determined from measured intensities via calibration with standards. 

Emission spectroscopy utilizes the characteristic line emission from atoms as their electrons drop from the excited to the ground state. The earliest version of emission spectroscopy as applied to chemistry was the flame test, where samples of elements placed in a Bunsen burner will change the flame to different colors (sodium turns the flame yellow calcium turns it red, copper turns it green). The modem version of emission spectroscopy for the chemistry laboratory is ICP-AES. In this technique rocks are dissolved in acid or vaporized with a laser, and the sample liquid or gas is mixed with argon gas and turned into a plasma (ionized gas) by a radio frequency generator. The excited atoms in the plasma emit characteristic energies that are measured either sequentially with a monochromator and photomultiplier tube, or simultaneously with a polychrometer. The technique can analyze 60 elements in minutes. 

Introducing samples to the plasma via liquids reduces sensitivity because the concentration of the analyte is limited to the volume of solvent that the plasma can tolerate. An electro-thermal method seems an obvious choice to increase the detection limit as it will vaporise entirely most neat samples or using an increased concentration of sample in a suitable solvent. The sample is placed on a suitable open graphite rod in an enclosed compartment and heated rapidly (Figure 2.15). The electronics required for ICP-OES-ETV (inductively coupled plasma-optical emission spectroscopy-electro-thermal volatilisation) is similar to that for A AS and detection limits are better than ICP-AES. 

The separation of yttrium from the lanthanides is performed by selective oxidation, reduction, fractionated crystallization, or precipitation, ion-exchange and liquid-liquid extraction. Methods for determination include arc spectrography, flame photometry and atomic absorption spectrometry with the nitrous oxide acetylene flame. The latter method improved the detection limits of yttrium in the air, rocks and other components of the natural environment (Deuber and Heim 1991 Welz and Sperling 1999).Other analytical methods useful for sensitive monitoring of trace amounts of yttrium are X-ray emission spectroscopy, mass spectrometry and neutron activation analysis (NAA) the latter method utilizes the large thermal neutron cross-section of yttrium. For high-sensitivity analysis of yttrium, inductively coupled plasma atomic emission spectroscopy (ICP-AES) is especially recommended for solid samples, and inductively coupled plasma mass spectroscopy (ICP-MS) for liquid samples (Reiman and Caritat 1998). 

During all the membrane separation experiments, feed and permeate were sampled periodically. Concentration of anserine and carnosine was analyzed with high-performance liquid chromatography (HPLC). Concentration of creatinine and sodium ion was determined with HPLC and ICP-AES (inductively coupled plasma-atomic emission spectroscopy), respectively. Then, rejection ability of a membrane against each component was calculated with Eq. 22.1 ... 

ICP emission spectroscopy is used primarily for the qualitative and quantitative analysis of samples that arc dissolved or suspended in aqueous or organic liquids. I he techniques for preparation of such solutions are similar lo tho.se described in. Section 9D-1 for flame absorption methods. With plasma emission, however, it is possible to analyze solid samples direclly. These procedures include incorporating electrothermal vaporization, la.ser and S[)ark ablation, and glow-discharge vaporization, all of which were described in Section 8C-2. Suspensions of solids in solutions can... 

Silicones have been extracted from environmental samples with solvents such as hexane, diethyl ether, methyl isobutylketone, ethyl acetate, and THF, using either sequential or Soxhlet techniques (690-695). Silicones of a wide range of molecular weights and polarities are soluble in THF. This feature, coupled with its volatility and miscibility with water, makes THF an excellent solvent for the extraction of silicones from wet samples, ie, soils and sediments. Trace levels of silicones extracted from environmental samples have been measured by a number of techniques, including atomic absorption spectroscopy (AA), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), pyrolysis GC-MS, as well as H and Si NMR spectroscopy (674,684,692,696-700). The use of separation techniques, such as gel permeation and high pressure liquid chromatography interfaced with sensitive, silicon-specific AA or ICP detectors, has been particularly advantageous for the analysis of silicones in environmental extracts (685,701-704). 

Figure 6.36 shows a variety of gas-phase techniques that have been used to synthesize 0-D nanoparticles. Radio frequency plasma sources have long been used for quantitative analysis by atomizing component species in liquid or solid samples - a technique referred to as inductively-coupled plasma atomic emission spectroscopy (ICP-AES). The extreme energy of an ICP may also be exploited to vaporize precursor sources to afford the growth of nanoparticles (Figure 6.36a). In this system, the nanoparticle size/morphology would be mostly controlled by the concentration of precursor in the plasma, and the rate of cooling - a function of its distance from the plasma source.

Principles and Characteristics Simultaneous multi-element analysis based on emission from a plasma generated by focussing a powerful laser beam on a sample (solid, liquid, or gas) is known as laser-induced breakdown spectroscopy (LIBS) and under a variety of semantic variations time-resolved LIBS (TRELIBS), laser ablation emission spectroscopy (LAES), laser ablation atomic emission spectrometry (LA-AES), laser ablation optical emission spectrometry (LA-OES), laser plasma emission spectrometry (L-PES), laser-induced plasma spectroscopy (LIPS), laser spark spectroscopy (LSS), and laser-induced emission spectral analysis (LIESA ). Commercial LIBS analysers were already available in the 60/70s the technique now enjoys a renaissance. 

In ICP-AES analysis, the liquid sample (i.e., solution) is nebulized into an inductively coupled plasma it has sufficient energy to break chemical bonds, liberate elements, and transform them into a gaseous atomic state for atomic emission spectroscopy. When this happens, a number of the elemental atoms will be excited and emit radiation. The wavelength of this radiation is characteristic of the element that emits it, and the intensity of radiation is proportional to the concentration of that element within the solution. The ICP-AES is used for both qualitative element identification and quantitative chemical composition determination. 

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