Spectrofluorimetric determination of nickel (ΙΙ) with murexide.

A very sensitive and selective spectrofluorimetric method has been developed for nickel (ΙΙ) determination in environmental samples. The method is based on measuring the decrease in fluorescence intensity of murexide after nickel (ΙΙ) binding. The intensity of the fluorescence emission peak was measured at ex/em 345/431 nm in several solutions with pH interval 3.0-7.0. The fluorescence intensity decrease was found to be linear in the concentration range of 0.007 mg.L(-1) to 0.1 mg.L(-1) and 0.1 mg.L(-1) to 20 mg.L(-1) of nickel (ΙΙ) by using 10(-4) M murexide at pH 3. The detection limit was found 0.004 mg.L(-1). Relatively large excesses of over 20 cations and anions do not interfere. The method was successfully applied to the analysis of nickel (ΙΙ) in sea, rain and ground water. This method is very precise and accurate (R.S.D. = 0.42% for the determination of 0.05 mg.L-(1) nickel in 10 replicates).

A novel method for determination of patulin in apple juices by GC-MS.

A reliable gas chromatography-mass spectrometry with a QuEChERS procedure has been developed and validated for detection and determination of patulin in apple juice. This procedure includes initial extraction step with acetonitrile, partitioning step by addition of magnesium sulphate, sodium carbonate and sodium chloride, and clean-up step using dispersive solid-phase extraction by addition of a mixture of magnesium sulphate and primary secondary amine sorbent. In order to increase GC adoptability of patulin, derivatisation step was performed using N,O-bis-trimethylsilyl trifluoroacetamide. Method recoveries of patulin from apple juice samples ranged from 79.9% to 87.9%. Limit of detection (LOD) and quantification (LOQ) were 0.4 and 1.3 µg/L, respectively. Relative standard deviations were lower than 9.5%. The developed method has been successfully applied to the analysis of patulin in apple juice samples.