The phrase "order of ppm" is correct and usable in written English.
Generally, it is used in scientific writing to refer to the concentration of a given material measured in parts per million. For example, "The average concentration of the arsenic in the sample was found to be 8 ppm, an order of magnitude less than the safety limit."
H2S concentration was of the order of 1 ppm, while SO2 concentration was 0.03 0.05 ppm.
Thus expected CO2 concentrations for a venue in compliance with ASHRAE Standard 62 should result in a concentration of the order of 850 ppm or less, and levels above 1000 ppm are consistent with poor ventilation.
For comparison, the shift changes that are caused by the presence of the N-terminal His tag are distributed throughout the entire protein, with an average shift value of 0.012 ppm and the largest values on the order of 0.18 ppm.
We report an organic field-effect transistor (OFET -based sensOFET -basedm printable materialsensor an unusually high sensitivity of 0.5 ppmadev fromammonia and with limit of detection on the order of 0.1 printable
For carbon dioxide flux estimation during well-mixed day-time conditions, the average concentrations have to be determined with standard error as small as 0.2 0.3 ppm, thus the average concentration measurement instrumental precision is required to be in the order of 0.1 ppm.
Data under analysis will reduce the uncertainty to the order of 0.5 ppm.
The concentrations of water in the gas streams are expected to be extremely small, i.e. of the order of 10 ppm by volume.
Results presented a good agreement between experimental and analytical value of the effective area as an order of 8 ppm difference and the 3% on the lambda.
By using standard samples which simulated the duckweed leaf, the Co concentration in the leaf in the order of 100 ppm could be quantitatively determined.
