Vaporized Hydrogen Peroxide Bio-Decontamination Q&A

Relative humidity measures only vaporized water in the air. Relative saturation measures both vaporized water and vaporized H₂O₂ in the air.

Read a more detailed explanation in Vaisala PEROXCAP® Sensor for Measuring Vaporized Hydrogen Peroxide, Relative Saturation and Relative Humidity.

You are also welcome to listen to one of our on-demand webinars on the topic:

Room Bio-Decontamination with Vaporized Hydrogen Peroxide (webinar recording)

Vaporized H₂O₂ Bio-decontamination in Isolators and Transfer Hatches (webinar recording)

RS% is the only parameter that tells you when an air mixture starts to condense.

a. Traceable measurement can be related to appropriate measurement standards, generally national or international, through an unbroken chain of comparisons

b. Vaisala’s HPP272 hydrogen peroxide measurement is traceable to the international system of units (SI) through national metrology institutes (NIST USA, MIKES Finland, or equivalent) or via ISO/IEC 17025 accredited calibration laboratories.

When powered on, the PEROXCAP sensor is heated, which permits using the probe in condensing H₂O₂ conditions, maintains measurement performance, and lengthens the probe's lifetime.

We have selected our materials based on numerous test runs including stability tests. In the probe body we use stainless steel (AISI316L), LCP (Liquid Crystal Polymers) and PTFE (Polytetrafluoroethylene).

The HPP272 probe has 2 analog outputs or digital MODBUS RTU over RS-485. It is compatible with Indigo transmitters for three analog outputs, optional display, relays and smartphone user interface.

Definition for sterilization process is: Any chemical or physical process which destroys all life forms, with special regard to microorganisms (including bacteria and bacterial spores), and inactivates viruses. Therefore the terms "sterile" and "sterilization", describe the absence and the destruction of all viable microorganisms.

Bio-decontamination is defined as removal of microbiological contamination or its reduction to an acceptable level.

Main differences between sterilization and bio-decontamination are also explained on our related on-demand webinar called "Vaporized H₂O₂ Bio-Decontamination in Isolators and Transfer Hatches".

Accuracy (including non-linearity, hysteresis, and repeatability) at +25 °C (77 °F), 10 ... 2000 ppm H₂O₂: ±10 ppm or 5 % of reading (whichever is greater).

HPP272 is only meant for process level / high level measurement. It is not meant for leakage / sub ppm measurement.

Typically in food and beverage industry you have continuous process where for example cups or bottles are bio-decontaminated prior to filling in. Typically very high concentration (e.g. 10000 ppm) for a short time (e.g. 8 seconds) is used to provide the required log reduction. The higher the ppm, the shorter can the bio-decontamination time be, in order to provide the required log reduction. Production turnaround time is the most important factor.

H₂O₂ is a very unstable gas and it is therefore difficult to make calibration in H₂O₂ environment. However, if you have, for example, a factory calibrated HPP272, and another HPP272 that you wish to calibrate, you can just compare the measurement results between these two. It is important that these two probes are installed close to each other to make sure they measure the same environment.

We are currently working on an onsite calibration capability for the HPP272 probe with Relative Humidity (RH). I.e. in the future you will be able to calibrate and adjust the HPP272 onsite using any humidity calibrator (for example Vaisala's HMK15) and Vaisala Insight software. With any humidity calibrator and the Insight software you are able to calibrate and adjust both H₂O₂ ppm and RH.

Your sensor's Relative Saturation (RS) reading will show 100% when condensation starts. Here is a reference to an article that discusses the relationships between humidity, hydrogen peroxide concentration and micro-condensation:

"The Influence of Humidity, Hydrogen Peroxide Concentration, and Condensation on the Inactivation of Geobacillus stearothermophilus Spores with Hydrogen Peroxide Vapor"
Beatriz Unger-Bimczok, Volker Kottke, Christian Hertel, Johannes Rauschnabel
Journal of Pharmaceutical Innovation (2008) 3:123–133 DOI 10.1007/s12247-008-9027-1.

Published online: 8 May 2008 # International Society for Pharmaceutical Engineering 2008. https://link.springer.com/article/10.1007/s12247-008-9027-1

Here is a direct link to the CDC document: https://www.cdc.gov/infectioncontrol/pdf/guidelines/disinfection-guidelines.pdf 
Here is also a link to the AAMI document: https://webstore.ansi.org/RecordDetail.aspx?sku=AAMI+TIR17%3a+2017

Unfortunately ANSI (American National Standards Institute) documents are not available for free, but they are available for orders online.

In September 2017 we have launched the new HPP272 probe that measures H₂O₂ vapor in ppm, humidity (both RH and RS) and temperature. Please see the product page here: www.vaisala.com/HPP272
 

Please contact our sales representative to discuss pricing. We have a wide network of sales teams and distributors in several locations who are happy to help. You can find the closest contact person here.

HPP272 is designed for high humidities. It measures humidity from 0% to 100%. The ppm measurement range is up to 2000 ppm. HPP272 is not for safety level measurement. Our accuracy specifications starts from 10 ppm onwards.

We know that in general RNA molecules are much more sensitive to degradation than DNA. It's also a well known fact that hydrogen peroxide ions cause oxidation of proteins, membrane lipids and DNA. [see Löffler G. and Petrides P. E.: Physiologische Chemie. 4 ed., p. 288, Springer, Berlin 1988, ISBN 3-540-18163-6 (in German)].

We haven't tested the effectivity of hydrogen peroxide against DNA. We would like to recommend to you that you search on the web if there are scientific studies made about H₂O₂ effectiveness against DNA/ RNA. Or you could make your own studies. Meanwhile, we would recommend other well known ways to destroy DNA and RNA to be sure about the effectivity. Such as UV-light alone or combined with higher temperature and specific chemical agents that are available commercially to destroy DNA and RNA residues. Such agents are typically used for example in PCR (polymerase chain reaction) applications.

Vaisala HPP272 is for high level / process level measurement only. HPP272 is not for safety ppm level measurement. I.e. HPP272 cannot state when you are able to open the door.

HPP272 provides many additional calculated parameters in addition to H₂O₂ ppm, humidity and temperature. For example HPP272 calculates absolute H₂O₂ in g/m3. Would absolute g/m3 suit your needs or would you prefer mg/L? We have chosen g/m3 because it is SI unit. However, unfortunately HPP272 does not stand for vacuum conditions.

HPP272 with capacitive thin film technology: Compared with still air, the response time is faster when there is air flow.

Electrochemical cells: We do not manufacture electrochemical cells and therefore cannot really comment on this issue.