Method and apparatus for determination of chemical species in body fluid

A dermal concentration patch for determining the presence of a photosensitive analyte in a subject mammal's perspiration, comprising:

• a water permeable support layer having a first side and a second side;
• and
• a vapor permeable attenuation layer on the second side of the support layer for attenuating the amount of light reaching the support layer, the attenuation layer having an adhesive thereon for securing the first side of the support layer in fluid communication with the subject's skin,
• wherein water is permitted to escape through the support layer and outside of the concentration patch.

A dermal concentration patch for determining the presence of a photosensitive analyte in a subject mammal's perspiration, comprising:

• a concentration zone for collecting and storing said photosensitive analyte, wherein said concentration zone has a first side and a second side, wherein said first side is capable of being placed in fluid communication with the subject's skin;
• an adhesive layer having a first side and a second side, wherein said first side is proximate to said second side of said concentration zone, for removably securing the first side of said concentration zone in fluid communication with the subject's skin;
• and
• an attenuation layer having a first side and a second side, wherein said first side is proximate to said second side of said adhesive layer, for attenuating the transmission of light into said concentration zone,
• wherein the concentration zone and the attenuation layer allow passage of aqueous components of sweat to outside of the concentration patch.

A method of determining the presence of a photosensitive analyte in perspiration of a subject mammal, comprising the steps of:

• securing a dermal patch having a concentration zone to the subject's skin, wherein said concentration zone is in fluid communication with the subject's skin;
• collecting perspiration containing said photosensitive analyte from said subject's skin in said concentration zone;
• attenuating the amount of photoradiation reaching said concentration zone during said collecting step, thereby protecting said photosensitive analyte from excessive photoradiation exposure;
• concentrating said photosensitive analyte in said concentration zone by allowing aqueous components of perspiration to pass through and escape from said dermal patch;
• and
• determining the presence of said photosensitive analyte in said subject's perspiration.