Electrochemiluminescence Interferometry at Microelectrodes

Electrochemiluminescence of the Ru(bpy)32+/S2O82- System in Purely Aqueous Solution at Carbon Paste Electrode

“…The maximum ECL intensity occurs at pH 7.0. The decrease of the ECL intensity observed in acidic solutions may be explained by the consumption of Ru(bpy) 3 The effect of silicone content on the ECL intensities is shown in Figure 6. The ECL intensity increases sharply with the ratio of silicone vs. graphite powder up to 3:5±4:5 (vaw) and drops off at higher ratios.…”

“…Since both ECL peaks are very weak, it indicates that the concentration of the excited-state Ru(bpy) 2 3 (Ru(bpy) 2Ã 3 ) was quite low. On the reverse scan, the ECL intensity decreases rapidly from À1.6 V to around À1.40 V because the concentration of the electrogenerated Ru(bpy) 3 decreases rapidly. After that, the ECL intensity changes very slowly.…”

“…The Ru(bpy) 2 3 ECL reaction can be initiated by three modes. The ®rst ECL reaction sequence is based on the annihilation of Ru(bpy) 3 and Ru(bpy) 3 3 , which are produced by application of the proper potential [2,3]. Another ECL reaction sequence is an oxidative-reduction type, such as the Ru(bpy) 2 3 aoxalate system and Ru(bpy) 2 3 atripropyl amine system [4,5].…”

“…The oxidative-reduction type ECL of Ru(bpy) 2 3 in aqueous solutions is well documented and has resulted in the recent development of highly sensitive detection schemes for many analytes [7±12]. Recently the ECL reaction involved in the annihilation of Ru(bpy) 3 and Ru(bpy) 3 3 has been obtained in water at carbon interdigitated micrelectrode arrays [13]. However, ECL reactions in aqueous solutions have not been reported at normal sized electrodes for the last two types, because Ru(bpy) 3 is unstable andaor the quenching of Ru(bpy) 2 3 * by S 2 O 2À 8 is very quick in fully aqueous solution [6].…”

“…Recently the ECL reaction involved in the annihilation of Ru(bpy) 3 and Ru(bpy) 3 3 has been obtained in water at carbon interdigitated micrelectrode arrays [13]. However, ECL reactions in aqueous solutions have not been reported at normal sized electrodes for the last two types, because Ru(bpy) 3 is unstable andaor the quenching of Ru(bpy) 2 3 * by S 2 O 2À 8 is very quick in fully aqueous solution [6]. Several methods have been developed for the determination of S 2 O 2À 8 , for example, a reductimetric method, a potentiometric method, a¯ame analytical method, and a Ru(bpz) 2 3 electrochemiluminescent method [14±19].…”