A new measurement technique of peroxyacetyl nitrate at parts per trillion by volume levels: Gas chromatography/negative ion chemical ionization mass spectrometry
H. Tanimoto et al., A new measurement technique of peroxyacetyl nitrate at parts per trillion by volume levels: Gas chromatography/negative ion chemical ionization mass spectrometry, J GEO RES-A, 104(D17), 1999, pp. 21343-21354
A new technique for measuring peroxyacetyl nitrate (PAN) at parts per trill
ion by volume (pptv) levels has been developed using gas chromatography wit
h negative ion chemical ionization mass spectrometry (GC/NICI MS). Four fra
gment ions, CH3C(O)O- (mass-to-charge ratios (m/z)=59), NO3- (m/z=62), CH3C
(O)OO- (m/z=75), and NO2- (m/z=46), were identified by NICI mass spectra. N
O3- (m/z=62) was used in selected ion monitoring (SIM) mode among these fra
gment ions, since it gave the best signal-to-noise (S/N) ratio, and a poten
tial interference from isopropyl nitrate (IPN) was excluded. Optimization o
f mass spectrometry and use of capillary gas chromatography enabled us to d
etect PAN at a retention time of 2.6 +/- 0.1 min in ambient air mixing rati
o range. The present detection limit is 15 +/- 4 pptv (S/N=3), which is com
parable to those of previously published GC/ECD methods, with good linearit
y at pptv levels. The instrumental accuracy and precision are estimated to
be +/-20% and +/-15%, respectively. Other PAN analogs (i.e., peroxypropiony
l nitrate and peroxymethacryloyl nitrate) were also measured within 10 min.
Exploratory ambient air measurements were made at our laboratory in a subu
rban area of Tokyo, Japan. These results demonstrated the performance of GC
/NICI MS for ambient air measurements.