Spray-inductively coupled plasma

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. 

Figure 5.1 Main parts of an inductively coupled plasma mass spectrometer sample introduction systems (left column), e.g., Meinhard or MicroMist nebulizer with cyclonic spray chamber, ultrasonic nebulizer, microconcentric nebulizer and laser ablation system (all from CETAC Technologies), ion source (middle column) and several types of mass spectrometers, (a) Agilent 7500 from Agilent, (b) Platform from CV Instruments, or (c) Element from Thermo Fisher Scientific. (Parts of this figure were reproduced with permission from CETAC Technologies, Agilent, CV Instruments and Thermo Tisher Scientific, respectively.)...

For these techniques, a dissolved sample is usually employed in the analysis to form a liquid spray which is delivered to an atomiser e.g. a flame or electrically generated plasma). Concerning optical spectrometry, techniques based on photon absorption, photon emission and fluorescence will be described (Section 1.2), while for mass spectrometry (MS) particular attention will be paid to the use of an inductively coupled plasma (TCP) as the atomisation/ionisation source (Section 1.3). The use of on-line coupled systems to the above liquid analysis techniques such as flow injection manifolds and chromatographic systems will be dealt with in Section 1.4 because they have become commonplace in most laboratories, opening up new opportunities for sample handling and pretreatment and also to obtain element-specific molecular information. 

Thompson and Zao [170] have described a solvent extraction-inductively coupled plasma atomic emission spectrometric method for the determination of down to 0.02 - 0.03 xg/g of molybdenum in soils. The soil sample is pressure-leached with 6 M hydrochloric acid and at 120 °C for 15 minutes. The digest is then extracted with heptan-2-one to separate molybdenum from potentially interfering elements such as iron, aluminium, calcium and magnesium. This organic extract is then directly sprayed into an inductively coupled plasma atomic emission spectrometer operated at 1.65 to 1.7 kW power. 

Rivas, C., Ebdon, L. and Hill, S.J. (1996) Effect of different spray chambers on the determination of organotin compounds by high-performance liquid chromatography inductively coupled plasma spectrometry.J. Anal. At. Spectrom., 11, 1147-1150. 

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. 

Apparatus Use a suitable Inductively Coupled Plasma Emission Spectrophotometer set to 226.502 nm for cadmium and to 371.029 for yttrium (internal standard) with an axial view mode. (This method was developed using a Perkin-Elmer Model 3300 DV equipped with a sapphire injector, low-flow GemCone nebulizer, cyclonic spray chamber, and yttrium internal standard.) Use acid-rinsed plastic volumetric flasks and other labware. 

An inductively coupled plasma source is made up of a hot flame produced by inductive coupling in which a solution of the sample is introduced as a spray [102-104], This source consists of three concentric quartz tubes through which streams of argon flow. As shown in Figure 1.44, a cooled induction coil surrounds the top of the largest tube. This coil is powered by an RF generator that produces between 1.5 and 2.5 kW at 27 or 40 MHz typically. The gas at atmospheric pressure that sustains the plasma is initially made... 

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.

POLLMANN D., PlLGER C., Hergenroder R., Leis F., Tschopel P. and Broekaert J. A. C. (1994) Noise power spectra of inductively coupled plasma mass spectrometry using a cooled spray chamber, Spectrochim Acta, Part B 49 683-690. 

Schutyser P. and Janssens E. (1979) Evaluation of spray chambers for use in inductively coupled plasma atomic emission spectrometry, Spectrochim Acta, Part B 34 443-449. 

B Hymer C., Sutton K. and Caruso J. A. (1998) Comparison of four nebulizer-spray chamber interfaces for the high-performance liquid chromatographic separation of arsenic compounds using inductively coupled plasma mass spectrometric detection, J Anal At Spectrom 13 855-858. 

Spraying of ZrO(NO3)2 Solution into Plasma Argon, ultrahigh-temperature inductively coupled plasma. 

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