company news about UV LED integrated into chromatographic detector

The process of UV LED replacing traditional deuterium lamps or xenon lamps is not just a replacement of the light source, but a system engineering involving optics, electronics and software.

Identify the UV absorption peaks of the primary compounds (analytes) to be detected by HPLC or GC. For example, many pharmaceutical ingredients and aromatic compounds absorb strongly around 254 nm, while proteins and nucleic acids absorb around 260 nm or 280 nm.

Based on the analyte absorption peak, select a UV-C or UV-B LED chip with an emission wavelength that most closely matches the analyte's absorption peak. For example, if 254 nm detection is required, a high-performance UV-C LED with a peak in the 250–265 nm range would be selected.

Determine the required light output power, spectral bandwidth (LEDs are generally narrower than deuterium lamps, a significant advantage), and thermal stability.

Ensure that the light emitted by the LED efficiently and stably passes through the mobile phase (flow cell). The selected UV LED chip should be packaged on a substrate with effective thermal management (such as copper or ceramic), as UV LED performance is extremely sensitive to temperature. An integrated high-efficiency heat sink (typically water cooling or Peltier element TEC cooling) ensures a stable LED junction temperature, thereby ensuring stable light output and minimizing spectral drift. A microlens array or parabolic reflector should be designed to collect and shape the wide-angle light emitted by the LED chip into a parallel beam (collimation). Traditional deuterium lamps are nearly point light sources, making the beam easy to manage; UV LEDs are surface light sources, requiring more sophisticated non-imaging optical designs to ensure beam uniformity and efficiency. The collimated beam is then directed into the chromatograph's flow cell (optical path length). The flow cell must be constructed of corrosion-resistant materials with high UV transmittance (such as quartz glass). The LED light source module is directly bonded to or integrated on both sides of the flow cell, replacing the bulky lamp housing and complex external optical fibers/light pipes of traditional deuterium lamps.

Design a highly stable, low-noise constant-current driver. UV LED light output is highly positively correlated with current; any current fluctuations will affect the detection baseline.

Implement a temperature feedback system (such as a PID controller) to monitor the LED junction temperature in real time and adjust the power of the TEC cooler to keep LED temperature fluctuations within a very tight range (e.g., ±0.1°C).

Leverage the instantaneous on/off characteristics of LEDs to achieve high-frequency light beam modulation (e.g., kHz level).

The receiver (photodiode) only detects light signals synchronized with the LED, thereby filtering out ambient background light interference and system electronic noise, significantly improving the signal-to-noise ratio (SNR) and detection sensitivity.

In the chromatography workstation software, this replaces the traditional "light source warm-up" interface with an "instant start" interface. The software also displays the real-time status and estimated lifespan of the LED, facilitating user maintenance.

• Instant-On: Eliminate the lengthy 15-30 minute warm-up time of deuterium lamps; instruments are instantly operational, significantly improving laboratory efficiency.
• Extremely Long Lifespan: UV LEDs offer a lifespan of over 10,000 hours, compared to the typical 1,000-2,000 hours for deuterium lamps. This significantly reduces operating costs and downtime for maintenance.
• Reduced Energy Consumption and Heat Dissipation: LEDs offer higher energy efficiency and more concentrated heat generation, requiring smaller and simpler cooling systems, enabling miniaturization and portability of instruments.