Mass spectrometry APCI

The term nebulizer is used generally as a description for any spraying device, such as the hair spray mentioned above. It is normally applied to any means of forming an aerosol spray in which a volume of liquid is broken into a mist of vapor and small droplets and possibly even solid matter. There is a variety of nebulizer designs for transporting a solution of analyte in droplet form to a plasma torch in ICP/MS and to the inlet/ionization sources used in electrospray and mass spectrometry (ES/MS) and atmospheric-pressure chemical ionization and mass spectrometry (APCI/MS). 

Crescenzi et al. developed a multi-residue method for pesticides including propanil in drinking water, river water and groundwater based on SPE and LC/MS detection. The recoveries of the pesticides by this method were >80%. Santos etal. developed an on-line SPE method followed by LC/PAD and LC/MS detection in a simultaneous method for anilides and two degradation products (4-chloro-2-methylphenol and 2,4-dichlorophenol) of acidic herbicides in estuarine water samples. To determine the major degradation product of propanil, 3,4-dichloroaniline, the positive ion mode is needed for atmospheric pressure chemical ionization mass spectrometry (APCI/MS) detection. The LOD of 3,4-dichloroaniline by APCI/MS was 0.1-0.02 ng mL for 50-mL water samples. 

Atmospheric Pressure Chemical Ionization Tandem Triple Quadrupole Mass Spectrometry (APCI/MS/MS)... 

Mass Spectrometry, APCI-MS/MS Zorbax RX-SIL, 5 p, 250 x 2.1 mm, hexane/isopropanol.ethyl acetate gradient p-carotene, a-T, p-cryptoxanthin. Lutein, zeaxanthin (20 min) Hao et al., 2005... 

In order to determine ureas and metabolites of triazines and ureas in agricultural soils, reverse-phase liquid chromatography was used with atmospheric pressure chemical ionization/mass spectrometry (APCI/MS), in positive mode. Gas chromatography/ion trap mass spectrometry was used in MS/MS mode to analyze the parent compounds of the triazines and chloroacetanilides. Method performance was much better in GC-MS/MS than in LC-MS, and acetochlor LOQ was dramatically improved by using GC-MS/MS, this herbicide being very poorly ionized into the APCI interface. 

Vogel, A.L., Aijaia, M., Briiggemann, M., Ehn, M., Junninen, H. Petaja, T, Worsnop, D.R., Kulmala, M., Williams, J., Hoffmann, T. (2013) Online Atmospheric Pressure Chemical Ionization Ion Trap Mass Spectrometry (APCI-IT-MS ) for Measuring Organic Acids in Concentrated Bulk Aerosol - a Laboratory and Eield Study. Atmos. Meas. Tech. 6 431-443. 

Table 6.9. Breath analysis of mouthspace and nosespace signal intensities relative to headspace intensities by atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) ...

Similar calculations have given the interactions energies for [H(OOCH2) OOH + NHtj (n = 2,3,4) as 39, 45, and 54 kcal/mol, respectively. The calculated interaction energies for [H(OOCH2) OOH -i- Na] (n = 2,3,4) were reported to be somewhat higher at 56, 77, and 80 kcal/mol, respectively [33]. These complexes are observed by ESI- and atmospheric pressure chemical ionization-mass spectrometry (APCI-MS), as discussed below. 

The reacting solution was first examined by atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The solutions were injected with a dual syringe pump into an effective micromixer, which was coupled directly to the ion source of the mass spectrometer. For comparison, two compounds were examined separately by APCI-MS, and the respective quasimolecular ions were observed. The radical cations 14 and 15 were characterized unambiguously by APCI-MS/MS (Figure 4.3). 

Stubiger, G., Pittenauer, E. and Allmaier, G. (2003) Characterisation of castor oil by on-line and off-line non-aqueous reverse-phase high-performance liquid chromatography-mass spectrometry (APCI and UV/MALDI). Phytochem. Anal. 14, 337-346. 

GC-FID, gas chromatography flame ionization detection GCMS, gas chromatography mass spectrometry APcI-TOFMS, atmospheric pressure chemical ionization-time of flight mass spectrometry PTRMS, proton-transfer-reaction mass spectrometry. 

In the case of the RAS (Fig. 4), the amounts of 2-heptanone released from samples containing 20%, 40%, and 60% saliva expressed as a percentage of the amount released from the 100% pure emulsion sample were 111%, 109%, and 93%, respectively. Similar results were observed for 1-butanol, hexanal, and butyl acetate the more hydrophobic compounds, i.e., those having a greater relative difference in values between samples (Fig. 2), maintained a higher than expected concentration in the headspace relative to the less hydrophobic compounds. Doyen and coworkers, using atmospheric pressure chemical ionization mass spectrometry (APcI-MS), also found that given both a compound s air/water and air/emulsion... 

---