Small-sized capillary electrophoresis with a chemiluminescence detector equipped with cross-intersection for sample injection.

been aggressively studied based on the concept of the micro total analysis system (µ-TAS). It is called microchip CE. Laser-induced fluorescence (LIF) has been most commonly used as a sensitive detection method in microchip CE. 1 However, LIF detection necessitates a laser light source or spectroscopes. An alternative sensitive detection scheme involves the use of chemiluminescence (CL). Because CL does not require any light source or spectroscopes, this technique holds tremendous promise for µ-TAS. Based on know-how obtained through our research of an ordinary CE with a CL detector, 2–4 we successfully developed a microchip CE with a CL detector. 5,6 Transition-metal ions and dansyl amino acids were analyzed by means of microchip systems using luminol 5 and peroxyoxalate reagent, 6 respectively. The microchip featured the simplest construction, in principle only two main channels, four reservoirs, a cross-intersection injector, and the absence of a mixing junction for the CL reaction. However, the microchips are expensive and difficult to handle. The microchannels on the microchip are often stopped up and hard to clean by channel washing. We proposed to develop a small-sized CE-CL detector equipped with a cross-intersection for sample injection. The small-sized CE-CL detector had the same construction as the microchip CE-CL detector, as mentioned above. A several-centimeter fused-silica capillary was used for separation instead of microchannel on a microchip. A fused-silica capillary is economical, exchangeable, and easily modified to a coated-or packed-capillary, compared to a microchip. Taking advantage of CL for detedtion miniaturized the whole system. The present CE-CL detector is matched to the concept of µ-TAS. Experimental Schematic layouts of the entire capillary channel and an enlargement of the cross-intersection part are illustrated in Fig. Ismatec, TYGON R3607) were used. Four reservoirs (R1 – R4) were made of silicone tubes (2.0 mm i.d. and ca. 5 mm length) and cover glasses (18 mm × 18 mm). The capillary length from the intersection to R4 (which corresponded to the effective separation length) was 30.0 mm. Other capillaries' lengths were 10.0 mm. The reservoirs and all of the capillaries with the intersection part were put on a slide glass (76 mm × 52 mm) and the Tygon-tube of the intersection part was fixed on the glass with a bonding agent. All chemicals were of analytical grade and were used without further purification. Ion-exchanged water was distilled before use. The capillaries were filled with a 25 mM CH3COOH–25 mM NaOH (70:30; …