"zero air" meaning in English

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  "lang_code": "en",
  "pos": "noun",
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          "name": "Zero",
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      "examples": [
        {
          "text": "For calibration, first pass a known range of concentrations of the gas through the gas chromatograph, for comparison with zero air that contains effectively none of the gas to be measured."
        }
      ],
      "glosses": [
        "atmospheric air specially cleaned so that it contains less than 0.1 ppm of hydrocarbon impurities; it then is usable in laboratory procedures such as versions of gas chromatography in which sufficiently pure air may serve as a carrier gas."
      ],
      "id": "en-zero_air-en-noun-Vq9CBl9C",
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          "atmospheric",
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        [
          "air",
          "air"
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          "ppm",
          "ppm"
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          "hydrocarbon",
          "hydrocarbon"
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          "laboratory",
          "laboratory"
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          "procedure",
          "procedure"
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        [
          "gas chromatography",
          "gas chromatography"
        ],
        [
          "carrier gas",
          "carrier gas"
        ]
      ],
      "wikipedia": [
        "en:Gas chromatography"
      ]
    }
  ],
  "sounds": [
    {
      "rhymes": "-ɛə(ɹ)"
    }
  ],
  "word": "zero air"
}

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  "lang_code": "en",
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        "en:Zero"
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          "text": "For calibration, first pass a known range of concentrations of the gas through the gas chromatograph, for comparison with zero air that contains effectively none of the gas to be measured."
        }
      ],
      "glosses": [
        "atmospheric air specially cleaned so that it contains less than 0.1 ppm of hydrocarbon impurities; it then is usable in laboratory procedures such as versions of gas chromatography in which sufficiently pure air may serve as a carrier gas."
      ],
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        "en:Gas chromatography"
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  "word": "zero air"
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