Carbon dioxide sensitive material

Details Carbon dioxide sensitive material Carbon dioxide sensitive material

1997-05-16

1998-12-15

Alexander, Lyle A.

Chemistry: analytical and immunological testing

Oxygen containing

Inorganic carbon compounds

436 2, 422 85, 422 86, 12820528, 73 233, G01N 3350

Patent

active

058495940

DESCRIPTION:

BRIEF SUMMARY
This invention relates to a carbon dioxide sensitive material for indicating whether a correct quantity of carbon dioxide has been flushed into a modified atmosphere package (MAP) and for indicating whether the concentration of carbon dioxide inside the package has diminished due to opening of or damage to the package.
In WO 91/05252 there is disclosed a carbon dioxide monitor which comprises a carbon dioxide sensitive material which changes colour in accordance with changes in concentration of carbon dioxide, the material comprising a lipophilic organic quaternary cation, an indicator dye anion, a polymer binder and a plasticiser. The concentration of carbon dioxide at which the materials change colour is generally below 5% and the material exhibits no further colour change when exposed to increased concentrations of carbon dioxide. The material is suitable for carbon dioxide monitoring in medical applications.
With modified atmosphere packaging, however, it is desired to monitor changes in concentrations of carbon dioxide in a package which are greater than 5%. For example, processed meat and fish are often packaged in an atmosphere containing 30% carbon dioxide, and red meat is often packaged in an atmosphere containing 100% carbon dioxide. The carbon dioxide sensitive materials known hitherto would be unsuitable for monitoring the concentration of carbon dioxide in MAP applications since such materials would change colour completely in an atmosphere containing 5% carbon dioxide, and a material in a package containing 5% carbon dioxide will exhibit the same colour as a material in a package containing 100% carbon dioxide.
It is desirable, therefore, to provide MAP with a carbon dioxide sensitive material which changes colour over a desired range of carbon dioxide concentrations.
According to the present invention there is provided a carbon dioxide sensitive material comprising a polymer binder, a plasticiser, a lipophilic organic quaternary cation, an indicator dye anion and an aromatic alcohol in such concentration that the material changes colour in accordance with concentration of carbon dioxide.
We have discovered that the colour of materials known hitherto changes significantly with temperature at constant carbon dioxide concentration. Consequently, it is impossible to determine the concentration of carbon dioxide unless the temperature is accurately known and, more importantly, unless the relationship between the temperature and the sensitivity of the material to carbon dioxide is known.
We have also discovered that known materials are more sensitive to carbon dioxide at lower temperatures than at higher temperatures. For example, at room temperature such a material might change colour when exposed to a 2% concentration of carbon dioxide, while at 0.degree. C. the material will change colour when exposed to a 0.5% concentration of carbon dioxide.
We have also discovered that for known materials lower temperatures result in lower reaction speed; a material which changes colour within a few seconds at room temperature may take minutes at a temperature below 4.degree. C.
Such a material would be unsuitable for a MAP application where it is desired to accurately sense a concentration of carbon dioxide in a package which is stored below 4.degree. C. since sensitivity of the materials to carbon dioxide and speed of reaction to carbon dioxide are dependent on temperature.
Therefore, it is also desirable to provide MAP with a carbon dioxide sensitive material which is less sensitive to changes in temperature than materials known hitherto.
In accordance with the present invention the plasticiser is selected from the group of compounds comprising adipates, phthalates and phosphates so as to determine, in use, reaction speed and sensitivity of the material to temperature.
Following is a series of Tables indicating the factors that control the sensitivity towards carbon dioxide, the temperature sensitivity and the reaction speed of the material in accordance with the present invention.
It has been found that

REFERENCES:
patent: 5407829 (1995-04-01), Wolfbeis et al.
Mills, Andrew et al., Equilibrium Studies on Colorimetric Plastic Film Sensors for Carbon Dioxide, Anal. Chem. (1992), 64(13), 1383-9 Coden: Ancham;ISSN: 0003-2700, 1992.

Affiliated with

Also associated with

Rating

Carbon dioxide sensitive material does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Carbon dioxide sensitive material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Carbon dioxide sensitive material will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1457167