Significant catalytic activity towards the reduction of nitrite at unmodified Cu - 30% Ni alloy electrodes was found within the concentration ranges 16 – 200 μM nitrite. The reduction of nitrite was found to occur at potentials significantly less negative than the reduction of nitrate thereby providing clear resolution and the possibility of reliable nitrite / nitrate speciation. The results are contrasted with those found at a bare copper electrode where the spatial resolution of the nitrate and nitrite reduction processes is severely limited with significant overlap of the reduction processes. The procedure represents an inexpensive and facile method for nitrite determination in a number of applications.

Two fluoroalcohols—1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol (HFTB)—were evaluated for the first time as volatile buffer acids in the basic mobile phase for reversed-phase chromatography with electrospray ionization-mass spectrometric (LC-ESI-MS) detection of five antibiotics. Chromatographic separation as well as positive and negative ion ESI-MS intensities using these novel buffer components were compared to traditional buffer systems. Overall, the highest signal intensities and best chromatographic separation for the five antibiotics (ciprofloxacin, norfloxacin, ofloxacin, sulfadimethoxine and sulfamethoxazole) were achieved using 5 mM HFIP as the buffer acid to methanol : water mobile phase (pH of the aqueous component adjusted to 9.0 with ammonium hydroxide). Comparable results were achieved using 5 mM HFTB (pH adjusted to 9.0 with ammonium hydroxide). The suitability of HFIP for analysis of antibiotic residues in lettuce is demonstrated.