Solvent and pH effects on fast and ultrasensitive 1,1'-oxalyldi(4-methyl)imidazole chemiluminescence.
Solvent and pH effects on fast and ultrasensitive 1,1'-oxalyldi(4-methyl)imidazole chemiluminescence (OD4MI-CL) were studied. The influences of these two factors on the complex OD4MI-CL reaction are discussed within a conceptual prototype for developing aqueous and non-aqueous capillary electrophoresis (ACE and NACE) devices with OD4MI-CL detection. The reaction channel length and OD4MI yield from the reaction between bis(2,4,6-trichlorophenyl) oxalate (TCPO) and 4-methylimidazole in the channel will be influenced by pH, water volume fraction, and cosolvent properties of the solution. Optimum OD4MI-CL efficiency is observed at pH 6.5 when 1-propanol, which has a low dielectric constant (epsilon = 20.8), is used as the NACE solvent in the separation channel. Water (epsilon = 80.1), the solvent in the ACE separation channel, acts similarly to a high dielectric constant organic solvent in NACE because the disadvantages normally associated with TCPO-CL reactions in water disappear due to the faster OD4MI-CL reaction versus OD4MI decomposition in aqueous solution. Therefore, it is expected that the OD4MI-CL detection system can be used in both NACE and ACE devices without requiring detector modifications. We also conclude that OD4MI-CL detection in NACE and ACE devices will be much more sensitive than the TCPO-CL detection used in current NACE devices.
Lee
Ji Hoon
JH
Clemson Institute of Environmental Toxicology, Clemson University, Pendleton, SC 29670, USA. lee@clemson.edu
Je
Jongtae
J
Hur
Jin
J
Schlautman
Mark A
MA
Carraway
Elizabeth R
ER
D019075:Electrophoresis, Capillary / Q000379:methods*; D004784:Environmental Monitoring / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles; D008163:Luminescent Measurements; D008164:Luminescent Proteins; D008832:Microchemistry / Q000379:methods; D009930:Organic Chemicals / Q000032:analysis*; D012997:Solvents
C481726:1,1'-oxalyldi(4-methyl)imidazole; D007093:Imidazoles; D008164:Luminescent Proteins; D009930:Organic Chemicals; D012997:Solvents