Limits...
Sub-parts per billion detection of trace volatile chemicals in human breath using selected ion flow tube mass spectrometry.

Ross BM - BMC Res Notes (2008)

Bottom Line: These were then analysed by SIFT-MS to calculate the limits of detection for each compound under conditions which mimic a single breath exhalation.For xylene and toluene the limits of detection was approximately 0.5 PPBV per 10 seconds of analysis time.Results gained using this level of sensitivity suggested the presence of low levels of the compounds indole and methylindole in human alveolar and static oral air, although further studies are necessary to confirm these findings.

View Article: PubMed Central - HTML - PubMed

Affiliation: Northern Ontario School of Medicine, Departments of Biology and Chemistry, and the Public Health Program, Lakehead University, Thunder Bay, Ontario, Canada. brian.ross@normed.ca

ABSTRACT

Background: Selected ion flow tube mass spectrometry (SIFT-MS) allows the real time quantification of trace gases in air. Due to its tolerance of high humidity levels the technique is particularly suited to the chemical analysis of breath. The detection limit of SIFT-MS has previously reported to be approximately 5 - 10 PPBV which is insufficient for the measurement of some low abundance constituents of breath. Recent developments in the design of SIFT-MS instruments have increased the ion precursor count rates. It is, however, unclear as to how these advances will affect instrument sensitivity for breath analysis.

Findings: Standard gases were prepared by adding known quantities of compounds present at zero or very low levels in breath (xylene and toluene) to either humidified bottled air or actual human breath. These were then analysed by SIFT-MS to calculate the limits of detection for each compound under conditions which mimic a single breath exhalation. For xylene and toluene the limits of detection was approximately 0.5 PPBV per 10 seconds of analysis time. Results gained using this level of sensitivity suggested the presence of low levels of the compounds indole and methylindole in human alveolar and static oral air, although further studies are necessary to confirm these findings.

Conclusion: Recent advances in SIFT-MS have increased the techniques sensitivity for breath analysis into the sub PPBV range enabling the real time quantification of low level trace gases in human breath.

No MeSH data available.


Related in: MedlinePlus

Detection of xylene and toluene added to humidified air and human breath. Xylene (A) or toluene (B) vapour were added to either humidified bottled air (circles) or human breath (triangles) contained in Tedlar bags to produce a range of concentrations in duplicate. The standards were introduced into the sampling line of the SIFT-MS and after a delay of 10 seconds xylene and toluene levels were measured by reaction with the H3O+ precursor for a period of 10 seconds. These values were then plotted against the calculated standard concentrations. The best fit linear regression line is shown for both bottled air (solid line) and human breath (dashed line).
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Figure 1: Detection of xylene and toluene added to humidified air and human breath. Xylene (A) or toluene (B) vapour were added to either humidified bottled air (circles) or human breath (triangles) contained in Tedlar bags to produce a range of concentrations in duplicate. The standards were introduced into the sampling line of the SIFT-MS and after a delay of 10 seconds xylene and toluene levels were measured by reaction with the H3O+ precursor for a period of 10 seconds. These values were then plotted against the calculated standard concentrations. The best fit linear regression line is shown for both bottled air (solid line) and human breath (dashed line).

Mentions: The water content of the gas samples prepared using humidified bottled air (5.8 ± 0.1% (mean ± SD) was similar to that of human breath. The concentration of xylene and toluene (measured by their reaction with the H3O+ precursor as previously described in detail [9]) in humidified bottled air prior to introduction of these chemicals was not differentiable from the instrument background i.e. that derived from the count rate determined in the absence of sampled air. Using a 10 second sampling period both xylene and toluene could be differentiated from background at concentrations of approximately 500 PPTV (Figure 1) with instrument blanks (sampling line closed) being approximately 0.5 cps for both compounds, while 500 PPTV resulted in approximately 2 cps product ions. Increasing concentrations of both compounds produced a linear rise in measured concentration over the concentration investigated (approximately 0 – 8 PPBV).


Sub-parts per billion detection of trace volatile chemicals in human breath using selected ion flow tube mass spectrometry.

Ross BM - BMC Res Notes (2008)

Detection of xylene and toluene added to humidified air and human breath. Xylene (A) or toluene (B) vapour were added to either humidified bottled air (circles) or human breath (triangles) contained in Tedlar bags to produce a range of concentrations in duplicate. The standards were introduced into the sampling line of the SIFT-MS and after a delay of 10 seconds xylene and toluene levels were measured by reaction with the H3O+ precursor for a period of 10 seconds. These values were then plotted against the calculated standard concentrations. The best fit linear regression line is shown for both bottled air (solid line) and human breath (dashed line).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2536665&req=5

Figure 1: Detection of xylene and toluene added to humidified air and human breath. Xylene (A) or toluene (B) vapour were added to either humidified bottled air (circles) or human breath (triangles) contained in Tedlar bags to produce a range of concentrations in duplicate. The standards were introduced into the sampling line of the SIFT-MS and after a delay of 10 seconds xylene and toluene levels were measured by reaction with the H3O+ precursor for a period of 10 seconds. These values were then plotted against the calculated standard concentrations. The best fit linear regression line is shown for both bottled air (solid line) and human breath (dashed line).
Mentions: The water content of the gas samples prepared using humidified bottled air (5.8 ± 0.1% (mean ± SD) was similar to that of human breath. The concentration of xylene and toluene (measured by their reaction with the H3O+ precursor as previously described in detail [9]) in humidified bottled air prior to introduction of these chemicals was not differentiable from the instrument background i.e. that derived from the count rate determined in the absence of sampled air. Using a 10 second sampling period both xylene and toluene could be differentiated from background at concentrations of approximately 500 PPTV (Figure 1) with instrument blanks (sampling line closed) being approximately 0.5 cps for both compounds, while 500 PPTV resulted in approximately 2 cps product ions. Increasing concentrations of both compounds produced a linear rise in measured concentration over the concentration investigated (approximately 0 – 8 PPBV).

Bottom Line: These were then analysed by SIFT-MS to calculate the limits of detection for each compound under conditions which mimic a single breath exhalation.For xylene and toluene the limits of detection was approximately 0.5 PPBV per 10 seconds of analysis time.Results gained using this level of sensitivity suggested the presence of low levels of the compounds indole and methylindole in human alveolar and static oral air, although further studies are necessary to confirm these findings.

View Article: PubMed Central - HTML - PubMed

Affiliation: Northern Ontario School of Medicine, Departments of Biology and Chemistry, and the Public Health Program, Lakehead University, Thunder Bay, Ontario, Canada. brian.ross@normed.ca

ABSTRACT

Background: Selected ion flow tube mass spectrometry (SIFT-MS) allows the real time quantification of trace gases in air. Due to its tolerance of high humidity levels the technique is particularly suited to the chemical analysis of breath. The detection limit of SIFT-MS has previously reported to be approximately 5 - 10 PPBV which is insufficient for the measurement of some low abundance constituents of breath. Recent developments in the design of SIFT-MS instruments have increased the ion precursor count rates. It is, however, unclear as to how these advances will affect instrument sensitivity for breath analysis.

Findings: Standard gases were prepared by adding known quantities of compounds present at zero or very low levels in breath (xylene and toluene) to either humidified bottled air or actual human breath. These were then analysed by SIFT-MS to calculate the limits of detection for each compound under conditions which mimic a single breath exhalation. For xylene and toluene the limits of detection was approximately 0.5 PPBV per 10 seconds of analysis time. Results gained using this level of sensitivity suggested the presence of low levels of the compounds indole and methylindole in human alveolar and static oral air, although further studies are necessary to confirm these findings.

Conclusion: Recent advances in SIFT-MS have increased the techniques sensitivity for breath analysis into the sub PPBV range enabling the real time quantification of low level trace gases in human breath.

No MeSH data available.


Related in: MedlinePlus