Design and performance of a light‐emitting diode detector compatible with a commercial capillary electrophoresis instrument

Abstract

Indirect photometric detection in capillary electrophoresis (CE) has been predominantly performed in the UV region, in part due to a lack of suitable high-intensity and low-noise light sources in the visible spectral region. A new photometric detector based on light-emitting diodes (LEDs) as light sources and compatible with a commercially available CE instrument has been designed and constructed and its performance evaluated. The utility of this detector was successfully demonstrated by the indirect photometric detection of anions using a dye as probe and absorbance measured in the visible region. The detector exhibited very low baseline noise (around 0.03 mAU), stable output, and improved upper limit of detection linearity (502 mAU) compared with previously used LED detectors. The detector was tested for indirect detection of anions separated with an electrolyte containing 4 mM Orange G as the indirect detection probe, 10 mM histidine as an isoelectric buffer, and 0.05% hydroxypropylmethylcellulose to suppress the electroosmotic flow. Extremely low detection limits were obtained ranging from 0.16-0.36 microM (excluding chloride 0.56 microM), with separation efficiencies in the range of 154,000-274,000 theoretical plates.

Portable capillary-based (non-chip) capillary electrophoresis

“…Photometric detection (PD) can particularly benefit from use of LEDs as light sources. A miniaturized PD with LED light source (PD-LED) was reported in 2004 by Johns et al [123] and subsequently used in numerous works, including Hutchinson et al in 2007 [62], in coupling with a commercially-available fully-portable CE analyzer (CE Resources [32]). The main advantage of the LED-PD detector for use in P-CE is its small size and low power consumption.…”

Sensitive determination of carbohydrates labelled with p‐nitroaniline by capillary electrophoresis with photometric detection using a 406 nm light‐emitting diode

“…Injections were performed hydrodynamically at a pressure of 170 mbar applied to the injection side of the capillary. An in-house constructed LED detector was used as described in detail previously [20]. The LED used in this work was a 5 mm ELN5UV LED purchased from Oatley Electronic (Oatley, NSW, Australia) with a maximum emission at 406 nm and emission peak half-width of 17 nm.…”

Bioanalytical profile of the l-arginine/nitric oxide pathway and its evaluation by capillary electrophoresis

“…LED-sources combined detectors can be especially useful for indirect detection in the UV/VIS region, e.g. detection of anions using a strongly absorbing electrolyte [276]. LED has excellent stability enabling very low instrumental noise and detector performance which in combination with low cost and inerrability comprises a very promising detection technology in terms of low cost and integration of disposable CE devises.…”