scholarly journals Estimation of sulfuric acid concentrations using ambient ion composition and concentration data obtained by ion mass spectrometry measurements (APi-TOF)

2021 ◽  
Author(s):  
Lisa Johanna Beck ◽  
Siegfried Schobesberger ◽  
Veli-Matti Kerminen ◽  
Markku Kulmala
Keyword(s):  
Mass Spectrometry ◽  
Sulfuric Acid ◽  
Atmospheric Pressure ◽  
Theoretical Expression ◽  
Ion Composition ◽  
Concentration Data ◽  
Mass Spectrometers ◽  
Physical Reasons ◽  
Flight Measurements ◽  
Chemical Ionisation

Abstract. Sulfuric acid (H2SO4, SA) is the key compound in atmospheric new particle formation. Therefore, it is crucial to observe its concentration with sensitive instrumentation, such as chemical ionisation inlets coupled to Atmospheric Pressure interface Time-of-Flight mass spectrometers (CI-APi-TOF). However, there are environmental conditions and physical reasons when chemical ionisation cannot be used, for example in certain remote places or flight measurements with limitations regarding chemicals. In these cases, it is important to estimate the SA concentration based on ambient ion composition and concentration measurements that are achieved by APi-TOF alone. Here we derive a theoretical expression to estimate SA concentration and validate it with accurate CI-APi-TOF observations. The developed estimate works very well during daytime and with SA concentrations above 2⋅106 cm-3.

scholarly journals Elemental composition and clustering behaviour of α-pinene oxidation products for different oxidation conditions

2015 ◽  
Vol 15 (8) ◽  
pp. 4145-4159 ◽  
Author(s):  
A. P. Praplan ◽  
S. Schobesberger ◽  
F. Bianchi ◽  
M. P. Rissanen ◽  
M. Ehn ◽  
...  
Keyword(s):  
Elemental Composition ◽  
Organic Compounds ◽  
Atmospheric Pressure ◽  
Molar Mass ◽  
Oxidation Products ◽  
Neutral Species ◽  
Mass Spectrometers ◽  
Comprehensive Picture ◽  
The Difference ◽  
Chemical Ionisation

Abstract. This study presents the difference between oxidised organic compounds formed by α-pinene oxidation under various conditions in the CLOUD environmental chamber: (1) pure ozonolysis (in the presence of hydrogen as hydroxyl radical (OH) scavenger) and (2) OH oxidation (initiated by nitrous acid (HONO) photolysis by ultraviolet light) in the absence of ozone. We discuss results from three Atmospheric Pressure interface Time-of-Flight (APi-TOF) mass spectrometers measuring simultaneously the composition of naturally charged as well as neutral species (via chemical ionisation with nitrate). Natural chemical ionisation takes place in the CLOUD chamber and organic oxidised compounds form clusters with nitrate, bisulfate, bisulfate/sulfuric acid clusters, ammonium, and dimethylaminium, or get protonated. The results from this study show that this process is selective for various oxidised organic compounds with low molar mass and ions, so that in order to obtain a comprehensive picture of the elemental composition of oxidation products and their clustering behaviour, several instruments must be used. We compare oxidation products containing 10 and 20 carbon atoms and show that highly oxidised organic compounds are formed in the early stages of the oxidation.

scholarly journals Potential of liquid chromatography–atmospheric pressure chemical ionisation tandem mass spectrometry for determination of fosetyl-aluminium residues in dried hops

2011 ◽  
Vol 22 (No. 1) ◽  
pp. 24-28
Author(s):  
J. Poustka ◽  
J. Hajšlová ◽  
K. Holadová ◽  
K. Nováková
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Atmospheric Pressure ◽  
Tandem Mass ◽  
Method Performance ◽  
Selective Determination ◽  
Pressure Chemical ◽  
Chemical Ionisation

New analytical procedure for the determination of fosetyl-aluminium in hop cones (also called “hops”) was developed. Liquid chromatography–atmospheric pressure chemical ionisation tandem mass spectrometry (LC–APCI-MS/MS) allowed a highly selective determination of this fungicide which facilitated the sample preparation. The sufficiently low detection limit (1 mg/kg of dried hops) with the acceptable method performance characteristics (RSD 9%, recovery 76% – at the level of 10 mg/kg) complies with the need to inspect the observance of maximal residual limit 100 mg/kg. The application of LC-MS technique thus provided an effective way of fosetyl-aluminium determination in the complex hops matrix.  

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