Inductively Coupled Plasma Spraying ICPS

Samples to be examined by inductively coupled plasma and mass spectrometry (ICP/MS) are commonly in the form of a solution that is transported into the plasma flame. The thermal mass of the flame is small, and ingress of excessive quantities of extraneous matter, such as solvent, would cool the flame and might even extinguish it. Even cooling the flame reduces its ionization efficiency, with concomitant effects on the accuracy and detection limits of the ICP/MS method. Consequently, it is necessary to remove as much solvent as possible which can be done by evaporation off-line or done on-line by spraying the solution as an aerosol into the plasma flame. 

For inductively coupled plasma atomic emission spectroscopy (ICP-AES) the sample is normally in solution but may be a fine particulate solid or even a gas. If it is a solution, this is nebulized, resulting in a fine spray or aerosol, in flowing argon gas. The aerosol is introduced into a plasma torch, illustrated in Figure 3.21. 

The typical ICP-MS instrument (Fig. 3.1) consists of a sample introduction system (a nebulizer and spray chamber), an inductively coupled plasma source, a differ-... 

Figure 1 Schematic diagram of a typical commercial inductively coupled plasma mass spectrometry (ICP-MS) instrument (A) liquid sample, (B) peristaltic pump, (C) nebulizer, (D) spray chamber, (E) argon gas inlets, (F) load coil, (G) sampler cone, (H) skimmer cone, (I) ion lenses, (J) quadrupole, (K) electron multiplier detector, (L) computer.

The elements Al, Mn, and Sr were determined by means of a Perkin-Elmer Optima 4300DV inductively coupled plasma emission spectrometry (ICP-AES) instrument (axial mode), equipped with an AS-90 Plus autosampler, a cross-flow nebulizer, and a Scott-type spray chamber in Ryton. The instrumental operating parameters are listed in Table 10.1. 

Other elements were measured by a Perkin-Elmer SCIEX ELAN 6100 DRCII Inductively Coupled Plasma Mass Spectrometry (ICP-MS) instrument equipped with a cyclonic spray chamber, a concentric nebulizer and a dynamic reaction cell (DRC). In the vented (standard) mode, no reaction gas is present in the cell and the instrument shows the typical characteristics of a quadrupole-based ICP-MS apparatus. When the gas is introduced into the cell an ion-molecule reaction takes place that can be tailored so as to eliminate spectroscopic interferences. Experimental conditions are summarized in Table 10.2. 

Instead of an electronic furnace, an r.f. inductively coupled plasma (ICP) is also used to generate high temperatures. This method is named a spray lCP technique and has been applied for a wide variety of oxides.Another variation of the spray pyrolysis is the spray- drying method that uses slurry or sol of metal... 

An inductively-coupled plasma (ICP) is an effective spectroscopic excitation source, which in combination with atomic emission spectrometry (AES) is important in inorganic elemental analysis. ICP was also considered as an ion source for MS. An ICP-MS system is a special type of atmospheric-pressure ion source, where the liquid is nebulized into an atmospheric-pressure spray chamber. The larger droplets are separated from the smaller droplets and drained to waste. The aerosol of small droplets is transported by means of argon to the torch, where the ICP is generated and sustained. The analytes are atomized, and ionization of the elements takes place. Ions are sampled through an orifice into an atmospheric-pressure-vacuum interface, similar to an atmospheric-pressure ionization system for LC-MS. LC-ICP-MS is extensively reviewed, e.g., [12]. 

Fig. 1 The inductively coupled plasma-mass spectrometer (ICP-MS) used as a detector for high-performance liquid chromatography (HPLC). The liquid sample passes through the capillary into a nebulizer where it is changed into an aerosol. The aerosol passes through a spray chamber and into the plasma. The analytes pass into the mass spectrometer. The CE interface is not in detail in this figure.

Analysis of Gasoline and Diesel Fuel Samples by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES), Using Pneumatic Nebulizer and Standard Spray Chamber... 

An analytical scheme was developed [3] to characterize both the concentration and nature of the selenium species present in the various streams measmed (Fig. 1). Because an in-depth discussion of all of the techniques would be beyond the scope of this paper, the reviewed work will focus on the efforts to measure total selenium as well as selenite, selenate, and selenocyanate. A Sciex Elan Model 6000 Inductively Coupled Plasma-Mass Spectrometer system equipped with a water-cooled spray chamber was used for all of the selenium measurements. The operating conditions used for the ICP-MS are presented in Table 2, while conditions for the IC are presented in Table 3. 

Inductively coupled plasma atomic absorption (ICP/AA) spectroscopy is used to determine the concentration of analytes in solution. It can measure concentrations as low as a few parts per billion. This method is commonly used to measure the atomic concentrations of mineralogical samples. The analytes must be in solution to be sprayed into a chamber and excited by a plasma. Upon relaxation energy is released with a specific wavelength. The wavelength corresponds to what atoms are present. The intensity of the energy is related to the concentration of the analjde present. ICP is quantitative, but it must be referenced against a set of standards that are used for comparison. 

Laser-ablation, inductively coupled-plasma mass spectrometry (LA-ICPMS) is an instrumental technique in which a laser-ablahon cell and ophcal microscope supplant the spray chamber/nebulizer apparatus of a standard ICP-MS instrument. Subsamples of questioned material are ablated from a solid sample via laser (often a pulsed Nd-YAG tuned to 266 or 213 nm). Ablated specimens are transported in a stream of Ar to a plasma torch for ionization and mass discrimination as per solution ICP-MS. Only minimal sample prep is required, and few restrictions are placed on the nature of questioned solid samples (Brundle et al. 1992 Vickerman 1998). While laser spot sizes can be reduced to several micrometers, sensitivity is degraded as a result, and usual spatial resolutions are on the order of 10-100 pm. Matrix-matched standards are also necessary for accurate trace-element and isotopic quantitative analyses in LA-ICPMS. Depending on the quality of such primary standards, LA-ICPMS accuracies are typically 1-10%, with limits-of-detection in the parts-per-billion (ppb) range (O Table 62.1). 

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