Microwave plasma torch

SOME NEW ADVANCES IN DEVELOPING MICROWAVE PLASMA TORCH SPECTROMETRY... 

Up to 30% hydrogen can be added to the carrier gas stream of a helium microwave plasma torch, in the determination of arsenic, bismuth and tin. The argon torch accepts up to 20% hydrogen LOD about 2.5 pg Sn/L, with linear dynamic range over 3 orders of magnitude23. 

Recently, Hieftje et al.15-16 equipped a small double-focusing mass spectrograph built in house with Mattauch-Herzog geometry with several ion sources (such as glow discharge, an inductively coupled plasma ion source or a microwave plasma torch) and a novel array detector for simultaneous ion detection. 

Diemer, J. and Heumann, K.G. (1997) Bromide/bromate speciation by NTI-IDMS and ICP-MS coupled with ion exchange chromatography. Fresenius J. Anal. Chem., 357,74-79. Duan, YX., Wu, M., Jin, Q.H. and Hieftje, G.M. (1995) Vapour generation of nonmetals coupled to microwave plasma-torch mass-spectrometry. Spectrochim. Acta B, 50,355-368. Ebdon, L., Hill, S. and Jones, R (1987) Interface system for directly coupled high performance liquid chromatography-flame atomic absorption spectrometry for trace metal determination./. Anal. At. Spectrom., 2, 205-210. 

Pack et al. described the coupling of GC separations to TOF-MS by utilization of a microwave plasma torch (MPT) [50]. This low-power microwave plasma source has exhibited excellent limits of detection for halogenated species. When such species are separated by GC, the simultaneous capabilities of TOF-MS allowed the monitoring of 12C and 35C1 simultaneously, thereby facilitating the determination of empirical formulas. Presumably, ion chromatographic separations, FIA systems, and other separations might also benefit from the capabilities of TOF-MS. 

In the case of a toroidal microwave discharge obtained in a microwave plasma torch, the frequency dependent noise stemming from the gas flow dynamics could also be found at a frequency of 150-250 Hz (Fig. 11) [39]. When using hydride... 

Fig. 104. Microwave plasma torch according to Jin et al. (Reprinted with permission from Ref. [456].)...

A microwave plasma torch can be operated very stably with argon as well as with helium and can be used as an ion source for time-of-flight mass spectrometry. Such a system, as described by Pack et al. [76], is very useful for element-specific detec-... 

A. C. and Hieftje G. M. (1994) Direct coupling of continuous hydride generation with microwave plasma torch atomic emission spectrometry for the determination of arsenic, antimony and tin, Spectrochim Acta, Part B 49 59-73. 

Pack B. W., Broekaert J. A. C., Guzowski J. P., Poehlmann J. and Hieftje G. M. (1998) Determination of halogenated hydrocarbons by helium microwave plasma torch time-of-flight mass spectrometry coupled to gas chromatography, Anal Chem 70 3957-3963. 

Engel U., Kehden A., Voces E. and Broekaert J. A. C. (1999) Direct solid atomic emission spectrometric analysis of metal samples by an argon microwave plasma torch coupled to spark ablation, Spectrochim Acta, Part B 54 1279-1289. 

C. (1998) Spatially resolved measurements and plasma tomography with respect to the rotational temperatures for a microwave plasma torch, J Anal At Spectrom 13 955-961. 

In addition to previously mentioned processes, the production of N-doped HO2 nanomaterials has been reported through other methods. These processes are ball milling of Ti02 in a NH3 water solution [413], heating Ti02 under NH3 flux at 500-600°C [414, 415], calcination of the hydrolysis product of Ti(S04)2 with ammonia as precipitator, decomposition of gas-phase TiCU with an atmosphere microwave plasma torch [416], ion implantation techniques with nitrogen [417] and N2 gas flux [418] (see Table 8). 

A more radically different approach for liquid sample introduction is the microwave plasma torch (MPT) (Figure 2). In a recent design three concentric tubes were used where the outer two brass tubes acted as a coaxial waveguide for the microwaves eliminating the need for a cavity. The iimer quartz channel was nonconducting and the heliiun plasma that was formed (at power levels 70-200W) was similar to the ICP plasma, having a central chaimel that was more efficient for sample introduction as described previously. A sheath gas was used to stabilize the MPT and reduce air entrainment. 

Elemental determinations in aqueous and acetonitrile containing solutions by atomic spectrometry using a microwave plasma torch,... 

SWCNTs, MWCNTs, and CNFs have been synthesized by a floating catalyst method with different tube diameters achieved by controlling the FcH/benzene mole ratio. It is evident that small FcH/C ratios yield SWCNTs, and higher ratios CNFs [35]. SWCNTs were synthesized by the CO disproportionation reaction on Fe catalyst particles formed by FcH vapor decomposition in a laminar flow aerosol (floating catalyst) reactor [31], A mixture of CH4/H2/Ar with added Fe(CO)j was reacted in the presence of a microwave plasma torch for the synthesis of MWCNTs covered by iron oxide nanoparticles (NPs) [33]. 

The microwave plasma torch, as described by Wu et al. [735], is well-suited for use as an ion source for mass spectrometry. With a 150 W MIP coupled with pneumatic nebulization and subsequent desolvation, elements with high ionization potentials such as C, F, P, S, Cl, Br, and I could be determined down to 0.01-0.1 pg/mL. 

OzMEN B., Matysik F. M., Bings N. H. and Broekaert (. A. C. (2004) Optimization and evaluation of dilferent chemical and electrochemical hydride generation systems for the determination of arsenic by microwave plasma torch optical emission spectrometry, Spectrochim. Acta, Part B 59 941-950. 

Jin Q., Zhu C., Borer M. and Hieetje G. M. (1991) A microwave plasma torch assembly for atomic emission spectrometry, Spectrochim. Acta, Part B 46 417-430. 

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