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The Vocus PTR-TOF offers unmatched sensitivity and mass resolving power for online detection of VOCs

A proton transfer reaction mass spectrometer (PTR-MS) with sub-ppt limits of detection and mass resolving power up to 15000

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Advantages of the Vocus PTR-TOF 

The Vocus PTR-TOF is a proton transfer reaction mass spectrometer (PTR-MS) that is used for sensitive, real-time detection of volatile organic compounds (VOCs) in industrial, laboratory, and field applications.   The instrument combines TOFWERK’s novel Vocus proton transfer reaction cell with our high performance time-of-flight technology to offer you market leading sensitivity and mass resolving power.

  • Revolutionary PTR Reaction Cell Design.  The proprietary Vocus reaction cell reduces wall losses and focuses ions to give you up to 10x the sensitivity of other commercial PTR-MS. Learn more about the Vocus technology
  • Ultra-Low Limits of Detection.  High sensitivity and low backgrounds combine to yield sub-ppt VOC limits of detection in seconds
  • Highest Available Mass Resolving Power.  Mass resolving power up to 15000 enables identification of isobaric compounds in complex mixtures
  • Automated Reagent Ion Switching. Switching between H3O+, NO+, O2+ expands the breadth of detectable compounds and resolves isomers.
  • Interchangeable Ion Sources.  Built on our API-TOF platform, the Vocus PTR-TOF allows you to interchange the Vocus PTR reaction cell with an array of other ion sources.  
  • Adaptable for Your Applications. Work with us to integrate the Vocus PTR-TOF into your existing sampling systems and workflows
  • Field-Ready Hardware. Compact, durable architecture brings laboratory-grade performance to challenging environments
  • Intuitive, Powerful Software. Easy-to-use data acquisition interface and Tofware graphical post-processing software for the analysis of high-resolution TOF data

Webinar: Vocus PTR-TOF Real-time VOC Analysis with Market Leading Performance

Webinar: Vocus PTR-TOF Real-time VOC Analysis with Market Leading Performance

Download Vocus PTR-TOF Brochure

 

Improving PTR-MS without Compromise

The unique Vocus ion molecule reactor (IMR) improves almost all aspects of PTR-MS performance, while maintaining critical specifications and reaction processes that have been established for conventional designs.  

These fundamental aspects of Vocus PTR-TOF performance are key to its fast, ultra-sensitive measurement of trace VOCs.

High Purity Reactant Ions

Vocus PTR-TOF mass spectra are dominated by protonated peaks and free of significant contributions from non-PTR reaction and therefore easily interpreted and quantified. Read More »

Simple Calibration

The Vocus PTR-TOF routinely detects a very large number of VOCs, including many for which standards are not available.  It is possible to calibrate for all detected compounds with good accuracy based on simple measurements of a small number of VOC standards. Read More »

Ultra-Fast Time Response

The combination of its efficient inlet system, heated reaction cell, and high sensitivity makes the Vocus PTR-TOF the optimum detector for high throughput or highly time resolved measurements of low volatility organic compounds. Read More »

Select a Vocus Model to Meet Your Measurement Needs

 Sensitivity cps/ppb
xylene

Limit of Detection (LOD)
1-min / 1-s, xylene

Resolving Power at  Specified Sensitivitya
M/ΔM
Maximum
Resolving Power
a
M/ΔM
SizePower
Max / Typical
2R100001 ppt  / 10 ppt 1000015000

160 kg
< 0.45 m3
480 x 615 x 1480 mm

600 / 590 W
100001 ppt  / 10 ppt50007000 120 kg
 < 0.35 m3
480 x 615 x 1130 mm
600 / 590 W
M800 <5 ppt, 1 min20002500 120 kg
 < 0.35 m3
480 x 615 x 1130 mm
600 / 590 W 
Elf500<20 ppt, 1 min500750 55 kg
< 0.125 m3
 380 x 500 x 650 mm
450 /400 W 

a. Each model can be operated with higher resolving power at reduced sensitivity.  

 

Sub-ppt limits of detection in seconds Calculated as 3 times the standard deviation of signal with ultra clean air and assuming the sensitivity of BTX.

 

Vocus Reaction Cell and Sampling Inlet

  • Heated inlet system up to 180 C
  • Temperature controlled water vapor source
  • Proprietary reagent ion source and ion-molecule reaction cell with RF-focusing
  • Automated reagent ion switching
  • Temperature controlled reaction cell, 50C – 120C
Sample Flow Rate50-500 sccm typical 150 sccm
Operating Pressure0.5 – 5 mbar typical 1-2 mbar
Axial GradientUniform linear field 0-5 V/mm
Reagent IonsH3O+, NO+, O2+

Components 

Standard

  • Online, automated gas calibration 
  • Standby valve to allow servicing of Vocus reaction cell hardware without venting
  • Data acquisition, data post processing, and automatic mass spectrometer tuning software
  • Touch screen control
  • Shipping container for deployment with no disassembly required

Options

  • Liquid calibration system 
  • GC or fast-GC  
  • VIA aerosol inlet 
  • Headspace autosampler 
  • Interchangeable ion sources.  Learn more about how our API-TOF platform allows easy interchange of ion sources. 

Vocus PTR-TOF Publications

2019

  1. Holzinger, R.; et al. Validity and limitations of simple reaction kinetics to calculate concentrations of organic compounds from ion counts in PTR-MS. Atmos. Meas. Tech. Discuss, in review 2019. DOI:10.5194/amt-2018-446 

2018

  1. Riva, M.; Rantala, P.; Krechmer, J. E.; Peräkylä, O.; Zhang, Y.; Heikkinen, L.; Garmash, O.; Yan, C.; Kulmala, M.; Worsnop, D.; and Ehn, M. Evaluating the performance of five different chemical ionization techniques for detecting gaseous oxygenated organic species. Atmos. Meas. Tech. Discuss. 2018, in review. DOI:10.5194/amt-2018-407
  2. Krechmer, J.; Lopez-Hilfiker, F; et al. Evaluation of a New Vocus Reagent-Ion Source and Focusing Ion-Molecule Reactor for use in Proton-Transfer-Reaction Mass Spectrometry. Analytical Chemistry 2018. In Focus \ DOI: 10.1021/acs.analchem.8b02641

Application Notes

Conference Presentations

Customer Research

TOFWERK Publications

Webinars

White Papers

Vocus is a Leap Forward in PTR Reaction Cell Design

Vocus_500

Traditional PTR reaction cell designs use a stack of metal lenses connected by a series of resistors to produce a linear drift field. The stable, tuneable drift field (E) enables precise control over the distribution of water clusters and the electrostatic reaction time. But, because of scattering and diffusion within the drift tube, many analyte ions are not transmitted out of the drift tube toward the mass analyzer – thereby limiting the achieved sensitivity.

The Vocus reaction cell maintains the operation parameters required for fast, quantitative PTR analysis, with two unique design features that significantly increase sensitivity. By superimposing an oscillating RF field on top of a DC field, analyte ions are focused toward the center axis of the reaction cell and efficiently transmitted into the mass analyzer. The reaction cell is built using a resistive glass tube, rather than the traditional lens stack. This allows the application of the RF focusing field, while producing a more uniform DC field than the traditional lens stack.

Read more about the Vocus reaction cell design and performance in Krechmer, Lopez-Hilfiker, et al, Analytical Chemistry, 2018.