Wy. Lee et Ta. Nieman, EVALUATION OF USE OF TRIS(2,2'-BIPYRIDYL)RUTHENIUM(III) AS A CHEMILUMINESCENT REAGENT FOR QUANTITATION IN FLOWING STREAMS, Analytical chemistry, 67(11), 1995, pp. 1789-1796
Three approaches are comparatively evaluated for the use of tris(2,2'-
bipyridyl)ruthenium(II), Ru(bpy)(3)(3+), as a chemiluminescent reagent
in flowing streams: (1) external generation of the reactive Ru(bpy)(3
)(3+) oxidation state followed by contact with the analyte, (2) in sit
u generation of the Ru(bpy)(3)(3+) species from a solution mixture of
the analyte and the Ru(bpy)(3)(2+) species as it passes through the re
action/observation cell, and (3) in situ generation of the Ru(bpy)(3)(
3+) species from the Ru(bpy)(3)(2+) species immobilized within the obs
ervation cell. Oxalate and proline were used as representative analyte
s for comparison of these three modes with respect to the influence of
experimental variables (reagent concentration, now rate, pH) and resu
lting analytical performance (detection limit, working range, measurem
ent precision). Additionally, a comparison was made of the relative EC
L intensities obtained for a variety of analytes including oxalate, am
ino acids, aliphatic amines, peptides, and NADH. We find that each app
roach has its unique set of strengths and weaknesses. The external gen
eration mode yields the most intense emission, especially for simple a
liphatic amines, but working curves have poor linearity, and emission
intensities have a large dependence on solution flow rate. The in situ
immobilized approach results in lower intensities but yields the wide
st linear dynamic ranges, is most conservative of reagent, and has a p
articular sensitivity advantage for proline and NADH determinations. T
he in situ solution mode is superior for the detection of amino acids
such as tryptophan, 5-hydroxytryptophan, and histidine and has time, c
onvenience, and reliability advantages.