On-Line Emission Analysis of Polycyclic Aromatic Hydrocarbons down to pptv Concentration Levels in the Flue Gas of an Incineration Pilot Plant with a Mobile Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometer

Abstract

A newly developed, mobile laser mass spectrometer (resonance-enhanced multiphoton ionization - time-of-flight mass spectrometer, REMPI-TOFMS) was applied to on-line measurements at a waste incineration pilot plant. REMPI-TOFMS combines the optical selectivity of resonance-enhanced multiphoton ionization with a time-of-flight mass analysis to give a two-dimensional analytical method. Special care was taken to build up a sampling and inlet system suitable for on-line measurements of large, semivolatile polycyclic aromatic hydrocarbons (PAHs). An effusive molecular beam inlet in combination with a fixed frequency UV laser (Nd:YAG at 266 nm or KrF excimer at 248 nm) was used. Under these conditions, many different PAHs can be ionized selectively from the complex flue gas matrix. For example, the achieved detection limit for naphthalene is in the 10 parts-per-trillion by volume (pptv) concentration range. Calibration was performed by using external concentration standards supplied in low ppbv concentrations. The instrumentation is sufficiently robust to be operated under industrial conditions at incineration plants, for instance. The REMPI mass spectra can be acquired at 5-50 Hz. Time profiles of the concentrations of different PAHs in the flue gas were monitored with a time resolution of 200 ms. Significant variations in the concentration profile of several PAHs up to mass 276 amu (e.g., benzo[ghi]perylene) and methylated PAHs have been observed while combustion parameters were changing. In summary, it was demonstrated that laser mass spectrometry (REMPI-TOFMS) enables a real-time on-line trace analysis of combustion flue gases or industrial process gases.

Analysis of Persistent Organic Pollutants at Sub-Femtogram Levels Using a High-Power Picosecond Laser for Multiphoton Ionization in Conjunction with Gas Chromatography/Time-of-Flight Mass Spectrometry

“…Figure 1 shows an expanded view of the data in the form of a two-dimension display in the region of tetrachlorodibenzo-p-dioxins (tetraCDDs) and tetrachlorodibenzofurans (tetraCDFs), measured using the picosecond laser. All native 12 C-congeners of tetraCDD/Fs, in addition to the 13 C-congeners that had been added to the sample solution as internal standards, could be clearly observed, and the intensity distributions of the isotope peaks were identical to those calculated from the natural abundance of the chlorine atom. Thus, tetraCDD/Fs as well as other CDD/Fs congeners can easily be identified using two-dimensional display data.…”

“…[11][12][13][14][15][16][17][18][19][20][21] The MPI technique reduces undesirable interfering signals and enables the acquisition of a mass spectrum with fewer fragment peaks.…”

Sensitive and Selective Analysis of Polychlorinated Dibenzo-p-dioxins/Dibenzofurans and Their Precursors by Supersonic Jet/Resonance-Enhanced Multiphoton Ionization/Time-of-Flight Mass Spectrometry

“…On the other hand, Zimmermann et al developed a capillary-based effusive inlet system, in which the tip of the capillary was positioned in the center of the two acceleration plates of the first stage of the ion source. 35 Using this system, researchers achieved a higher overlap of the sample and the ionization laser. Subsequently, a capillary-based supersonic molecular beam nozzle was developed by restricting the top of the capillary, resulting in an increased sensitivity and selectivity.…”

Online Monitoring of a Styrene Monomer and a Dimer in an Emulsion via Laser Ionization Time-of-Flight Mass Spectrometry

“…[1][2][3] This method has advantages that include selectivity, rapidity, and robustness. 4,5 Therefore, LI-TOFMS is used extensively in the measurement of complex environmental samples, [6][7][8][9][10][11] biological molecules, 12 bioactive substances, 13 and polymers. 14,15 Emulsions are heterogeneous systems where one liquid is dispersed into another as droplets.…”