Portable Collection Devices for the Study of Deep-Lung Volatile Organic Compounds (VOC’s)

The RTube™ End Tidal Air Collector is designed for ease of use by the supervised patient in the clinic, home, school, or hospital. This non-invasive handheld device is fully self-contained and disposable. The RTubeVOC selectivly traps the last bit of exhalate containing primarily alveolar air as the subject fully exhales a single breath into the device.

This unique feature allows for easy integration of the RTubeVOC into deep-lung VOC studies and when used in conjunction with Mass Spectrometry allows data to be collected with ease from subjects in nearly any environment. The simplicity and environmental flexibility of this collector offers the potential for rapid development of clinical diagnostics utilizing Volatile Organic Compounds derived from the deep lung and alveoli.

Product Features

  • Evolutionary design has been proven safe and reliable in over 200,000 collections
  • Sealable collection tube allows short-term specimen storage for transport
  • Easily interfaces with any mass spectrometer using our Universal Needle Interface
  • Optimized for use with the upcoming Respiratory Research Portable Mass Spectrometer
  • Custom valve/piston traps End Tidal Air and allows the controlled, contamination-free discharge of the exhalate into the analyzer
  • Disposable design ensures a clean device ready for use at any time with no risk of infectious disease transmission between patients
  • Simple handheld device is easy to use by just about anyone

How to Use

The video outlines the procedures for use. A couple of points to consider:

  • In an adult, End Tidal Air is typically considered to be the last bit of exhalate trapped after a single continuous exhalation lasting 6 seconds or more
  • In a child, End Tidal Air is typically considered to be the last bit of exhalate trapped after a single continuous exhalation lasting 3 seconds or more
  • Continuous exhalation is required for the device to work correctly. Inhaling through the device at the end of the exhalation may contaminate the sample with ambient air


The RTube is CE Marked under the Medical Device Directive (93/42/EEC) and the In Vitro Diagnostic Directive (98/79 EC).

FDA Regulatory Status of the RTube family of products

RTube is registered with the United States Food and Drug Administration as a Class I device for the collection of expired gas. The RTube can be incorporated into most clinical investigations in the United States.

This of course does not mean it is exempt from individual entity’s Institutional Review Board or Human Investigation Committee. For research protocols, each individual Institutional Review Board/ Human Investigation Committee may wish to make its own determination as to the non-significant risk nature of the device, especially if the device is modified or incorporated into other equipment such as ventilator circuits.

Institutional Review Board/ Human Investigation Committee Consideration of the RTube family of products

Over 200,000 samples have been collected with the RTube over the last 15 years with zero adverse events attributed to its use. Our device and methods have been considered non-significant risk by multiple Institutional Review Boards. Each individual Institutional Review Board/ Human Investigation Committee may wish to make its own determination as to the non-significant risk nature of the device, especially if the device is modified or incorporated into other equipment.

Technical Information

How it Works

The RTubeVOC is strictly a non-rebreathing device and utilizes two one-way valves to maintain unidirectional flow throughout the entire breathing cycle as the subject exhales through the mouthpiece.


Our commitment to quality extends far beyond our product. At Respiratory Research, Inc., it is a way of business. We require that leading industry quality practices be applied to all products and processes. This includes Supplier Qualifications, Engineering, Procurement, Manufacturing, Order Fulfillment, and Technical Support.

We work with ISO 9000-certified suppliers only. Top-tier suppliers are provided current engineering documentation at all times and apply their own internal quality systems to ensure that all products supplied to Respiratory Research, Inc. are in full conformance with these engineering specifications. Respiratory Research, Inc. thoroughly and completely documents all product requirements using engineering drawings bills of material, assembly procedures, environmental specifications, and component specifications. These are maintained by Respiratory Research, Inc. and are under full revision control.

RTubeVOC Materials and Performance

The Rtube Exhaled Breath Condensate Collector is specifically designed to meet the needs of a wide range of subjects, investigators, and clinicians. Its size, weight, materials, and performance characteristics have been carefully selected to provide the maximum safety, effectiveness, and flexibility.

Physical Specifications RtubeVOC Transportable Cartridge
Envelope Dimensions 22.2 cm Tall X  2.6 cm Wide X 2.6 cm Long
Weight 17 grams


Material Specifications Rtube
Mouthpiece Polyethylene
Tube Copolymer Polypropylene
Duckbill Valve Silicone Rubber (FDA-approved Ingredients)
Oring PTFE (Teflon)
Endcaps Medical-grade Vinyl
Label Mylar


Performance Specifications Adult Child
Duration of Collection 6 Seconds 3 Seconds
Volume of End Tidal Air 65 ml 65 ml
Flow Resistance 0.40 cm H2O/liter


Cautions and Warnings

A WARNING, if unheeded, could potentially affect the patient.

A CAUTION, if unheeded, could potentially affect the quality of the sample or present a hazard to the medical and laboratory staff.


The RTube is a disposable device designed for single use. It is assembled to stringent specifications and cleaned under strictly controlled clean-room conditions to ensure proper operation, safety, and cleanliness. Any subsequent rebuilding or tampering with the device will reduce the effectiveness of the device, risk the quality of your data, and potentially pose a safety risk to the patient.

CAUTION: Device for investigational use only

The RTube is an investigational device only and is designed for research purposes. Due to the non-invasive nature of the device, the RTube is exempt from the Investigational Device Exemption of the United States Food and Drug Administration. Any invasive use of the device or use outside of protocols approved by local Institutional Review Boards is not supported by Respiratory Research, Inc.

CAUTION: Rapid or forceful manipulation of tube when inserted onto Universal Needle Interface may result in sample leakage

The RTubeVOC should be handled with a slow, steady, controlled motion when inserting onto plunger. This steady motion should be maintained even if unpredictable resistance levels are met. If excessive force is used and the resistance unexpectedly drops, the rapid motion of the RTube as it is forced over the plunger can distort the internal parts and can result in partial loss of sample

CAUTION: If separated, the mouthpiece and collection chamber must be properly mated to allow exhalation through the device.

Prior to use, please check to ensure the red arrow at the end of the collection chamber is pointing AWAY from the blue mouthpiece assembly.

The RTube collection chamber houses one of the two internal one-way check valves and must be properly oriented when attached to the mouthpiece. This collection chamber is easily identified as the long semi-clear polypropylene tube sitting atop the blue mouthpiece assembly. By design, these parts can easily be separated to allow isolation and transport of the sample within the chamber. The initial mating is done at the factory and quality checked to ensure correctness. However, during handling by patients or medical staff they can become separated. This is not a problem as long as they are mated correctly prior to use.

Note: The word “UP” is printed in red letters beneath the red arrow and pertains to the overall device orientation during use, not the assembly of the collection chamber to the mouthpiece.

CAUTION: If stored in a warm environment for an extended period of time the RTubeVOC may exhibit increased resistance upon first attempt to use.

This resistance is due to minor adhesion internal to the duckbill valve. The duckbill valve is made of silicone rubber. Silicone rubber, especially at warm temperatures, is a naturally tacky material. We minimize this tackiness through a curing process ensuring all volatiles are removed and that all residual reactions of the two-part reagent chemical mix used to create the compound are complete.

Even with this cure, the area around the slit of the valve may still experience light sticking when the RTubes are stored for longer than 30 months or stored in warm ambient temperatures.

This sticking is expected and normally has no effect, but in rare cases it can be enough to impair usage of the RTube. Apply the procedure shown here prior to using RTube to verify proper operation and eliminate any potential impairment. Please Note: It is important that all staff handling the RTubeVOC be made aware of this procedure.