SIFT Applications in Mass Spectrometry

Smith, David; Španěl, Patrik

doi:10.1006/rwsp.2000.0278

Cited by 15 publications

(8 citation statements)

References 11 publications

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“…Positive ions are created in an ion source and from the mixture of ion species a current of ions of a given mass-to-charge ratio is obtained using a quadrupole mass filter (Smith & Adams, 1987;Smith & Š paněl, 1995Smith & Š paněl, , 1999. The ions are injected into a fast-flowing inert carrier gas (usually pure helium at a pressure of $100 Pa ($1 Torr)) through a Venturi-type orifice (diameter typically 1-2 mm).…”

Section: A Principle Of the Sift Techniquementioning

confidence: 99%

Selected ion flow tube mass spectrometry (SIFT‐MS) for on‐line trace gas analysis

Smith

Španěl

2004

Mass Spectrometry Reviews

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699

935

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Selected ion flow tube mass spectrometry (SIFT-MS) is a new analytical technique for the real-time quantification of several trace gases simultaneously in air and breath. It relies on chemical ionization of the trace gas molecules in air/breath samples introduced into helium carrier gas using H(3)O(+), NO(+), and O(2) (+.) precursor ions. Reactions between the precursor ions and trace gas molecules proceed for an accurately defined time, the precursor and product ions being detected and counted by a downstream mass spectrometer, thus effecting quantification. Absolute concentrations of trace gases in single breath exhalation can be determined by SIFT-MS down to ppb levels, obviating sample collection and calibration. Illustrative examples of SIFT-MS studies include (i) analysis of gases from combustion engines, animals and their waste, and food; (ii) breath and urinary headspace studies of metabolites, ethanol metabolism, elevated acetone during ovulation, and exogenous compounds; and (iii) urinary infection and the presence of tumors, the influence of dialysis on breath ammonia, acetone, and isoprene, and acetaldehyde released by cancer cells in vitro. Flowing afterglow mass spectrometry (FA-MS) is briefly described, which allows on-line quantification of deuterium in breath water vapor.

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Section: A Principle Of the Sift Techniquementioning

confidence: 99%

Selected ion flow tube mass spectrometry (SIFT‐MS) for on‐line trace gas analysis

Smith

Španěl

2004

Mass Spectrometry Reviews

Self Cite

699

935

View full text Add to dashboard Cite

show abstract

“…The determination of the rate coefficient, k, of ion-molecule reactions using the SIFT technique has been described in many papers [26,27]. In brief, it requires a measurement of the decay rate of the reactive ion at the downstream end of the SIFT as controlled and measured flow rates of the reactive neutral gas/vapour are introduced into the helium carrier gas.…”

Section: Determination Of Rate Coefficients and Product Ion Distribut...mentioning

confidence: 99%

A study of sulfur-containing compounds in mouth- and nose-exhaled breath and in the oral cavity using selected ion flow tube mass spectrometry

2008

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We have carried out a selected ion flow tube mass spectrometry (SIFT-MS) study of the concentrations of the sulfur-containing compounds H(2)S (using H(3)O(+) precursor ions), CH(3)SH (H(3)O(+)), (CH(3))(2)S (O(2)(+)), (CH(3))(2)S(2) (NO(+)) and CS(2) (O(2)(+)) in single exhalations of mouth-exhaled breath and nose-exhaled breath and in the static gas in the oral cavity for two healthy volunteers. The primary purpose of the study was to show how compounds present in breath at levels as low as a part per billion (ppb) can be identified and quantified if the overlap of 'impurity' isobaric ions with the analytical product ions for each trace compound is identified and accounted for. The H(2)S measurements are straightforward using H(3)O(+) precursor ions, since no overlapping ions are recognized and its breath concentration is relatively high at typically 20-70 ppb. Thus, its concentration distribution for two healthy volunteers has been obtained over a period of a few weeks. The situation is very similar for CH(3)SH, but to analyse this compound we had to study the kinetics of its reactions with the SIFT-MS reagent ions H(3)O(+), NO(+) and O(2)(+) in order to provide the required kinetics library data for this compound. It is seen that CH(3)SH, (CH(3))(2)S and (CH(3))(2)S(2) are present in the mouth breath/cavity at lower levels of <10 ppb. The measurements of the levels of H(2)S and these compounds in the nose-exhaled breath and the closed mouth indicate that they are largely produced in the oral cavity, although there is some indication that (CH(3))(2)S is partially systemic in these two volunteers. It was not possible to quantify CS(2) in the breath because of serious interference (overlapping ions) due to the presence of carbon dioxide and acetone that inevitably occur in exhaled breath. This study paves the way for the accurate analysis of these sulfur compounds in halitosis and potentially for probing the diseased state, especially liver disease, by breath analysis. To demonstrate the simplicity of measuring these compounds when they are present at levels of about 100 ppb and greater, data are presented on the emissions of these sulfur-containing compounds from Pseudomonas bacterial cultures in vitro.

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“…Â íàñòîÿùåå âðåìÿ äëÿ îïðåäåëåíèÿ ìàðêå-ðîâ è èõ êîíöåíòðàöèîííûõ èçìåíåíèé ïðèìå-íÿåòñÿ ñëîaeíàÿ è äîðîãîñòîÿùàÿ àíàëèòè÷åñ-êàÿ òåõíèêà, íàïðèìåð, îáîðóäîâàíèå äëÿ ìàññ ñïåêòðîìåòðèè [2] èëè ðàçëè÷íûõ âèäîâ ñïåêò-ðîñêîïèè [3]. Òàêîé ïîäõîä îïðàâäàí â èññëå-äîâàòåëüñêîé äåÿòåëüíîñòè, íî ìàëî äîñòóïåí äëÿ øèðîêîãî èñïîëüçîâàíèÿ â êëèíè÷åñêîé ïðàêòèêå.…”

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“…Îáùàÿ ôîðìóëà äàííûõ ñîåäèíåíèé -[N-AlkQn](TCNQ) 2 , ëèáî [N-Alk-iso-Qn](TCNQ) 2 . Õàðàêòåðíîé îñîáåííîñòüþ êðèñòàëëè÷åñêîé ñòðóêòóðû òàêèõ âåùåñòâ ÿâëÿåòñÿ óïàêîâêà ìîëåêóë â ñòîïêè ñ ïåðåêðûòèåì ýëåêòðîííûõ âîëíîâûõ ôóíêöèé âíóòðè ñòîïîê è ñëàáûìè ñâÿçÿìè ìåaeäó ñòîïêàìè [5].…”

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“…Ïðè èñïîëüçîâàíèè â êà÷åñòâå òîêîïîäâî-äÿùåãî ìåòàëëà ìåäè îäíèì èç îñíîâíûõ ïðî-äóêòîâ àíîäíîãî ïðîöåññà ÿâëÿåòñÿ ñëîaeíàÿ ñîëü Cu(TCNQ) 2 . Ýòî íåñòîéêîå ñîåäèíåíèå ðàçëàãàåòñÿ â ñîîòâåòñòâèè ñ ðåàêöèåé: Cu(TCNQ) 2 → Cu(TCNQ) + TCNQ, ïðîäóêòû êîòîðîé ìîaeíî ðàññìàòðèâàòü êàê àêòèâíóþ ìàññó, îáåñïå÷èâàþùóþ óñòîé÷èâûé âî âðåìåíè ïîòåíöèàë.…”

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