Analysis of tear glucose concentration with electrospray ionization mass spectrometry.
We have developed a mass spectrometry-based method that allows one to accurately determine the glucose concentration of tear fluid. We used a 1 microL micro-capillary to collect tear fluid from the tear meniscus with minimal irritation of the eye. We analyzed the 1 muL volume of collected tear fluid with liquid-chromatography electrospray ionization mass spectrometry with the use of D-glucose-6,6-d2 as an internal standard. Repeated measurements and a recovery experiment on pooled, onion-induced tears showed that the analysis of the glucose in tears was precise (4% relative standard deviation) and provided 100% recovery. We found the tear glucose concentration of one fasting nondiabetic subject to be 13 to 51 microM while the onion-induced tear glucose concentration of a different nondiabetic subject to be 211 to 256 microM.
Taormina
Christopher R
CR
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Baca
Justin T
JT
Asher
Sanford A
SA
Grabowski
Joseph J
JJ
Finegold
David N
DN
D002851:Chromatography, High Pressure Liquid; D005947:Glucose / Q000032:analysis* / Q000378:metabolism; D006801:Humans; D012016:Reference Values; D021241:Spectrometry, Mass, Electrospray Ionization; D013666:Tears / Q000737:chemistry* / Q000378:metabolism
D005947:Glucose