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So, I need to measure the concentration of Benzene in air. I have an Arduino Zero to read analog or digital value.

I found out the sensor MQ-135. The problem is that, if I'm right, the sensor reacts also to different gasses as NH3 and alcohol.

Is the sensor reliable for such a measure or do I need to look somewhere else? Adapting sensors to the Arduino analog input is not a problem nor power supply of the sensor. My project measure temperature and humidity so, I can also adapt the measure to these two factors.

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closed as off-topic by brhans, Chris Stratton, Oleg Mazurov, Brian Carlton, Finbarr Sep 21 at 16:21

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  • \$\begingroup\$ The question has nothing to do with the Arduino platform. I suggest you remove that from the question and just say that you will be monitoring the output with a 0 to 5 V microcontroller ADC. \$\endgroup\$ – Transistor Sep 12 at 9:08
  • \$\begingroup\$ Arduino zero is 0 - 3.3 V... \$\endgroup\$ – NicoCaldo Sep 12 at 9:17
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    \$\begingroup\$ OK. So only that ADC specification is all that needs to be in the question in relation to the microcontroller - if it is needed at all. \$\endgroup\$ – Transistor Sep 12 at 9:40
  • \$\begingroup\$ I don't think there is a specific sensor for only benzene in market, unless some proprietary ones. These cheap sensors respond to a class of organic compounds, rather than a specific organic compound. \$\endgroup\$ – Mitu Raj Sep 19 at 15:17
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If the sensing resistance would be 100kOhm, what would be your verdict? CO2? NH4 in somewhat less concentration?
This sensor measures several gases, so it could be anything!

So, either pick a sensor that solely measures benzene (no idea if it exists) or pick a few more different sensors that e.g only measure alcohol and NH3 and another that only measures NH3 and CO2 etc and make a kind of truth table to determine the real gas based on the values of all these sensors.

(Above sensor examples are illustrative, I don't know by heart what combinations there are)
Quick search on internet shows e.g. CJMCU-4541 would be a candidate to exclude CO / NO2 / H2 / NH3 / CH4 etc.

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