Abstract
A method for the determination of trace levels of Cu and Zn in vivo using microdialysis coupled on-line with direct injection nebulization and inductively coupled plasma mass spectrometry ( Microdialysis-DIN-ICP-MS ) has been developed and optimized. The operation parameters of the DIN-ICP-MS system were first optimized with the use of ringer reagent, the perfusate used for microdialysis, to obtain maximum achieveable sensitivity and precision, and minimum interference caused by the matrix substances. A notably high blank resulted most probably from the sample injection system was suppressed pronouncedly by the use of a homemade PEEK syringe system, and the spectral interference for the measurement of Cu ( m/z=63 ) caused by 40Ar23Na was eliminated effectively by the measurement of 65Cu. The signal suppression by the matrix components could be corrected with the use of yittrium as an internal standard. After the establishment of DIN-ICP-MS system, the microdialysis was on-line coupled to it to form a continuous in vivo analytical system for the determination of Cu and Zn in animals. The effect of perfusate rate on the recovery of analyts was first investigated. The calibration curve was subsequently prepared with the use of artificial cerebral spinal fluid, as a simulating brain tissue, based on the optimized experimental condition. With the use of the established microdialysis-DIN-ICP-MS system, the detection limits down to ng/mL levels, with relative standards deviation of ≦10%, could be achieveable. The on-line analytical system is proved to be useful that is capable of near-real-time analysis of Cu and Zn with a temporal resolution of less than 10 min in anesthetized or awake, freely moving animals.