How do Capillary Electrophoresis work?
In capillary electrophoresis a fused-silica capillary of 25–100 micrometres internal diameter is filled with a background electrolyte or sieving polymer and connected between two buffer vials with electrodes. A few nanolitres of sample are injected hydrodynamically or electrokinetically and 5–30 kV is applied. The narrow bore dissipates heat efficiently, so high fields can be used, giving fast and sharp separations. Ions migrate according to their charge-to-size ratio, and in capillary zone electrophoresis electroosmotic flow from the charged silica wall carries all species toward the detector. Gel or polymer sieving separates DNA and SDS-protein complexes by size, while isoelectric focusing resolves proteins by pI. Detection is by UV absorbance or diode array, laser-induced fluorescence or mass spectrometry, and data are processed as electropherograms.
Which Capillary Electrophoresis variants are available?
- Capillary Zone Electrophoresis System with UV-DAD Detection — A single-capillary instrument with UV or diode-array detection at 190–600 nm that separates ions, peptides, drugs and charge variants by charge-to-size ratio.
- Multi-Capillary Array Genetic Analyzer with Laser-Induced Fluorescence — An automated 4 to 24-capillary array instrument with laser-induced fluorescence detection that sizes labelled DNA fragments and performs Sanger sequencing.
- Capillary Gel Electrophoresis System for CE-SDS Protein Analysis — A CE instrument configured with UV detection at 220 nm, sieving gel and method kits for CE-SDS, measuring size purity and fragments of monoclonal antibodies under reduced and non-reduced conditions.
- Capillary Isoelectric Focusing (cIEF) System — A capillary instrument that focuses proteins along a pH gradient formed by carrier ampholytes and images or detects them by isoelectric point, used to profile charge variants of antibodies and recombinant proteins.
- Microchip Capillary Electrophoresis System — A benchtop instrument that runs DNA, RNA or protein samples through microfluidic chips with embedded channels and fluorescence detection, sizing and quantifying 10–12 samples in minutes from only 1–5 microlitres of sample; it suits routine quality control where speed matters more than maximum resolution.
How do I choose the right variant?
Choose by application first. Capillary zone electrophoresis with UV or diode-array detection covers small ions, peptides, drugs and charge variants. Multi-capillary array analyzers with laser-induced fluorescence suit STR typing, fragment analysis and sequencing. Gel-based CE-SDS is the standard for size purity of monoclonal antibodies, and capillary isoelectric focusing resolves charge heterogeneity. Microchip formats trade resolution for speed and low sample use. Compare capillary count, detection type and sensitivity, temperature control, injection repeatability, autosampler capacity, and the software's audit trail and validation package for regulated use. Also consider consumable cost, such as capillaries, polymer and buffers, and whether the supplier can provide IQ/OQ documentation and method transfer support.
Where are Capillary Electrophoresis used?
Capillary Electrophoresis are specified in monoclonal antibody purity and charge variants, STR profiling for forensic identity, DNA fragment sizing and genotyping, small-ion and organic acid analysis and sanger sequencing.
Which standards and certifications apply?
Work with Capillary Electrophoresis is commonly governed by USP <1053>, Ph. Eur. 2.2.47, IEC 61010-1, IEC 60825-1, 21 CFR Part 11 and ISO 18385. Instrument certifications such as CE marking are confirmed per configuration and never assumed.
What are the key considerations before purchase?
Install the instrument on a stable bench with clean power, controlled ambient temperature and, for fluorescence systems, stable laser and optics conditions. Condition new capillaries according to the method, and flush between runs to maintain reproducible electroosmotic flow. Use filtered, degassed buffers and keep vials free of particles, since blockages and bubbles are the most common faults. Replace capillaries, polymer and windows on schedule, and verify performance with size standards or system suitability mixtures. Regulated users should plan IQ/OQ/PQ, calibration and software validation, with audit trails under 21 CFR Part 11. Safety follows IEC 61010-1 with interlocked high-voltage compartments, and laser safety under IEC 60825-1 applies to fluorescence detectors.
