Reduction of carbon monoxide interference in gaseous analyte detectors
Highly sensitive devices for detecting nitric oxide and/or other gaseous analytes in gaseous samples are improved by the incorporation of a carbon monoxide scavenger in the interior of the device or in the device packaging. The release of carbon monoxide within the housing of the device by the plastic used in the construction of the housing or by anything within the device that releases carbon monoxide causes a loss in sensitivity due to competition between the carbon monoxide and the nitric oxide for the binding sites on the device sensor. The scavenger corrects this by either catalyzing the oxidation of carbon monoxide to the less competitive carbon dioxide or immobilizing the carbon monoxide by affinity-type or covalent binding. Analogous effects are achieved for analytes other than nitric oxide but that likewise encounter interference from carbon monoxide in binding to sensors.
1. In a device for detecting nitric oxide in a gas sample, said device comprising a sensor that binds both said nitric oxide and carbon monoxide and undergoes a detectable change when bound to said nitric oxide, said sensor retained in a housing that is constructed of or further retains a carbon monoxide-releasing material, the improvement in which said device further comprises a carbon monoxide scavenger retained within said housing or within packaging enclosing said housing and is confined to a localized region that is removed from said sensor by a distance of about 3 mm to about 300 mm, such that any variation in nitric oxide detection caused by said scavenger is less than the greater of 1 ppb of nitric oxide or 10% of the level of nitric oxide detected.
2. In a device for detecting nitric oxide in a gas sample, said device comprising a sensor that binds both said nitric oxide and carbon monoxide and undergoes a detectable change when bound to said nitric oxide, said sensor retained in a housing that is constructed of or further retains a carbon monoxide-releasing material, the improvement in which said device further comprises a carbon monoxide scavenger separated from said sensor by a flow-restricting orifice that limits any variation in nitric oxide detection caused by said scavenger to less than the greater of 1 ppb of nitric oxide or 10% of the level of nitric oxide detected.
3. In a device for detecting nitric oxide in a gas sample, said device comprising a sensor that binds both said nitric oxide and carbon monoxide and undergoes a detectable change when bound to said nitric oxide, said sensor retained in a housing that is constructed of or further retains a carbon monoxide-releasing material, the improvement in which said device further comprises a carbon monoxide scavenger separated from said sensor by a diffusion-lowering membrane that limits any variation in nitric oxide detection caused by said scavenger to less than the greater of 1 ppb of nitric oxide or 10% of the level of nitric oxide detected.
4. In a device for detecting nitric oxide in a gas sample, said device comprising a NO sensor consisting of cytochrome C encapsulated in a sol gel matrix and retained in a housing that is constructed of or further retains a carbon monoxide-releasing material, the improvement in which said device further comprises a carbon monoxide scavenger retained within said housing or within packaging enclosing said housing.
5. The device of claims 1 , 2 , 3 , or 4 wherein said carbon monoxide scavenger is a transition metal oxide that causes the oxidation of carbon monoxide.
6. The device of claims 1 , 2 , 3 , or 4 wherein said carbon monoxide scavenger is a member selected from the group consisting of manganese dioxide, cupric oxide, and nickel oxide, and mixtures thereof.
7. The device of claims 1 , 2 , 3 , or 4 wherein said carbon monoxide scavenger is a mixture of manganese dioxide and cupric oxide.
8. The device of claims 1 , 2 , 3 , or 4 wherein said carbon monoxide-releasing material is a polymeric material incorporated in said housing.
9. The device of claims 1 , 2 , 3 , or 4 wherein said carbon monoxide-releasing material is a member selected from the group consisting of an acrylic resin and a polycarbonate.
10. The device of claims 1 , 2 , 3 , or 4 wherein said carbon monoxide-releasing material is an acrylic resin.
11. The device of claims 1 , 2 , 3 , or 4 wherein said carbon monoxide scavenger is a metal or metal oxide that causes the oxidation of carbon monoxide.
12. The device of claims 1 , 2 , 3 , or 4 wherein said carbon monoxide-releasing material is a polymeric material incorporated in said housing and said carbon monoxide scavenger is a granulated solid that constitutes from about 0.005 to about 0.3 part by weight of scavenger per 100 parts by weight of said polymeric material.
13. The device of claims 1 , 2 , 3 , or 4 wherein said carbon monoxide-releasing material is a polymeric material incorporated in said housing and wherein said carbon monoxide scavenger is a granulated solid that constitutes from about 0.01 to about 0.1 part by weight of scavenger per 100 parts by weight of said polymeric material.
14. The device of claim 1 wherein said localized region is from about 3 mm to about 300 mm from said sensor.
15. The device of claim 1 wherein said localized region is from about 10 mm to about 100 mm from said sensor.