RESUMEN
A glucose biosensor was fabricated from a glucose oxidasE-immobilized by chitosan and oxygen electrode. The effects of concentration of chitosan(0.3%), enzyme loading(0.8 mg), pH 7.0, phosphate buffer concentration(300 mmol/L), and temperature 25 ℃ for the response of the biosensor were investigated. The glucose biosensor has a linear response range of 0.016-1.10 mmol/L with a detection limit of 8.0 μmol/L(S/N=3). The response time was less than 60 s. The biosensor showed extremely good stability with a shelf-life of at least 3 months. The biosensor exhibited good repeatable response to a 0.25 mmol/L glucose olution with a relative standard deviation of 2.5%(n=10). The precision of fabrication of the biosensors using four different membranes was good with a RSD of 4.7%. Some common potential components in sample such as niacinamide, vitamin B6, vitamin B12, vitamin E, Ca2+, Mg2+, K+ and Zn2+ showed no interferences on the response of the glucose biosensor. The biosensor was successfully applied to determine the glucose in commercial beverage samples.
RESUMEN
OBJECTIVE:To prepare the inclusion compound of ?-carotene and study its stability. METHODS: Inclusion compound of ?-carotene with ?-CD was prepared by improved saturated water solution method. The stability of the inclusion compound was investigated by UV spectrophotometry and the content of ?-carotene was determined as well. RESULTS: In the inclusion compound, the content of ?-carotene was 5.54%. The stability of cyclodextrin complexed ?-carotene under heating, exposure to ultraviolet light and oxidizing agent was improved, and the remaining rate of ?-carotene increased by 34.4%, 1.8%, and 64.2%, respectively. CONCLUSION: The stability of ?-carotene was increased after encapsulation with ?-CD.