Development of an easily adaptable, high sensitivity source for inlet ionization

Unexpected ionization processes were recently discovered for use in mass spectrometry in which no added energy is required to convert condensed-phase molecules to gas-phase ions with ESI-like charge states by simply introducing the matrix/analyte sample into the sub-atmospheric pressure of the mass spectrometer.

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Towards a hand-held, fast, and sensitive gas chromatograph-ion mobility spectrometer for detecting volatile compounds

Analytical and Bioanalytical Chemistry ◽

10.1007/s00216-020-03059-9 ◽

2020 ◽

Author(s):

André Ahrens ◽

Stefan Zimmermann

Keyword(s):

Gas Phase ◽

Ion Mobility ◽

Atmospheric Pressure ◽

Response Times ◽

Atmospheric Pressure Chemical Ionization ◽

Real Life ◽

High Sensitivity ◽

Resolving Power ◽

Gas Chromatograph ◽

Ionization Processes

AbstractIon mobility spectrometers can detect gaseous compounds at atmospheric pressure in the range of parts per trillion within a second. Due to their fast response times, high sensitivity, and limited instrumental effort, they are used in a variety of applications, especially as mobile or hand-held devices. However, most real-life samples are gas mixtures, which can pose a challenge for IMS with atmospheric pressure chemical ionization mainly due to competing gas-phase ionization processes. Therefore, we present a miniaturized drift tube IMS coupled to a compact gas chromatograph for pre-separation, built of seven bundled standard GC columns (Rtx-Volatiles, Restek GmbH) with 250 μm ID and 1.07 m in length. Such pre-separation significantly reduces chemical cross sensitivities caused by competing gas-phase ionization processes and adds orthogonality. Our miniaturized GC-IMS system is characterized with alcohols, halocarbons, and ketones as model substances, reaching detection limits down to 70 pptv with IMS averaging times of just 125 ms. It separates test mixtures of ketones and halocarbons within 180 s and 50 s, respectively. The IMS has a short drift length of 40.6 mm and reaches a high resolving power of RP = 68.

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Determination of the Force Constants of Non-linear XY2 Molecules in the Gas-Phase by the GF Matrix Method

Zeitschrift für Naturforschung A ◽

10.1515/zna-2004-0913 ◽

2004 ◽

Vol 59 (9) ◽

pp. 621-622 ◽

Cited By ~ 1

Author(s):

Fatih Ucun ◽

Vesile Gūçlü

Keyword(s):

Gas Phase ◽

Condensed Phase ◽

Matrix Method ◽

Solid Phase ◽

Force Constants ◽

Matrix Solution ◽

The Matrix ◽

Newton Raphson ◽

Raphson Method

The force constants of the internal coordinates of nonlinear XY2 molecules in the gas-phase were calculated by using the GF matrix method. The matrix solution was carried out by means a computer program built relative to the Newton-Raphson method and the calculations were listed in a table. The force constants of some molecules in the liquidand solid- phase were also found and compared with these ones, and it was seen that the force constants for more condensed phase are lower as in an agreement with having its lower frequency.

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Photoproducts of the Photodynamic Therapy Agent Verteporfin Identified via Laser Interfaced Mass Spectrometry

Molecules ◽

10.3390/molecules25225280 ◽

2020 ◽

Vol 25 (22) ◽

pp. 5280

Author(s):

Chris Furlan ◽

Jacob A. Berenbeim ◽

Caroline E. H. Dessent

Keyword(s):

Mass Spectrometry ◽

Photodynamic Therapy ◽

Macular Degeneration ◽

Gas Phase ◽

Mass Spectrometer ◽

Red Light ◽

Solution Phase ◽

Collision Induced Dissociation ◽

Free Base ◽

New Information

Verteporfin, a free base benzoporphyrin derivative monoacid ring A, is a photosensitizing drug for photodynamic therapy (PDT) used in the treatment of the wet form of macular degeneration and activated by red light of 689 nm. Here, we present the first direct study of its photofragmentation channels in the gas phase, conducted using a laser interfaced mass spectrometer across a broad photoexcitation range from 250 to 790 nm. The photofragmentation channels are compared with the collision-induced dissociation (CID) products revealing similar dissociation pathways characterized by the loss of the carboxyl and ester groups. Complementary solution-phase photolysis experiments indicate that photobleaching occurs in verteporfin in acetonitrile; a notable conclusion, as photoinduced activity in Verteporfin was not thought to occur in homogenous solvent conditions. These results provide unique new information on the thermal break-down products and photoproducts of this light-triggered drug.

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