Vaporized H2O2 bio-decontamination is a highly relevant topic especially within the life science industry but also other industries using the ecological H2O2 in bio-decontaminating equipment and facilities.
In our webinars "Room Bio-Decontamination with Vaporized Hydrogen Peroxide" and "Vaporized Hydrogen Peroxide Bio-Decontamination in Isolators and Transfer Hatches" we have gone through several topics related to H2O2 bio-decontamination and we have received a lot of questions. The webinars are available on-demand via the above links, but let's go the questions and answers.
Please scroll down to see the Q&A section - the latest questions have been added on January 25th, 2018.
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 (pdf).
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 RauschnabelJournal 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.
Piritta Maunu has 15 years of experience in biotechnology, having worked in several quality management positions. Maunu holds a degree of M.Sc. (Cell Biology) and is certified to teach with a specialty in General Biology, both degrees from the University of Jyväskylä, Finland. In her role at Vaisala, she supports the sales department, assists the quality department with audits, creates educational content for life science customers, and provides application support to R&D teams creating solutions for monitoring critical environments.