CCD and CID solid-state detectors

Importance of the topic

The replacement of photomultiplier tube detectors by solid-state charge transfer devices such as charge-coupled devices and charge injection devices in inductively coupled plasma optical emission spectrometry has driven major advances in sensitivity, flexibility and throughput.

Study objectives and overview

This paper reviews the evolution of solid-state detectors in ICP-OES, compares the performance characteristics of CCD and CID technologies and introduces the design features and analytical advantages of the Agilent VistaChip II detector in the 720/725 Series instruments.

Methodology and instrumentation used

Key elements of the detector systems are described below:

• Echelle optics optimized for two-dimensional detector arrays and true simultaneous measurement
• Peltier cooling to sub-zero temperatures (typically down to –35 °C) to minimize dark current
• Detector designs:
  • Charge-coupled devices with back-illumination, thinned silicon dioxide layers and doped coatings to improve UV transmission
  • Charge injection devices with fluorescent coatings for enhanced low-UV sensitivity
• Adaptive Integration Technology for per-pixel real-time integration time adjustment
• Anti-blooming circuitry on every pixel to protect against charge overflow
• Hermetic sealing in inert gas to eliminate purge gas requirements

Main results and discussion

The Agilent VistaChip II delivers the combined benefits of CCD sensitivity and low noise with CID-style pixel control and non-destructive readout. It comprises 70,000 pixels arranged in 70 linear arrays matched to the echelle spectral format, covering 167 to 785 nm. With 1 MHz readout speed, adaptive integration from 1 µs to 100 s and eight orders of dynamic range, the detector achieves low detection limits, high precision and minimal pixel saturation. Hermetic sealing and triple-stage Peltier cooling maintain stable performance without maintenance delays or moisture risks.

Benefits and practical applications

Solid-state detectors in modern ICP-OES offer:

• True simultaneous measurement of up to 73 elements with a single detector
• Increased sample throughput and faster analysis times compared to sequential scanning systems
• Flexible wavelength selection without the need for multiple PMTs or pre-programming
• Lower total cost of ownership through reduced maintenance, gas consumption and instrument footprint
• Improved precision and lower detection limits for trace and major element analysis in environmental, industrial and research laboratories

Future trends and opportunities

Advances likely to shape the next generation of solid-state detectors include:

• Further improvements in UV quantum efficiency through novel coatings and silicon treatments
• Integration of higher density pixel arrays for expanded dynamic range and resolution
• Enhanced ruggedization for field-portable and process-monitoring applications
• Data-driven signal processing and real-time analytics using machine learning
• Hybrid detector architectures combining multiple charge-transfer principles

Conclusion

The transition to CCD and CID detectors has revolutionized ICP-OES by delivering significant gains in analytical performance, operational flexibility and productivity. The Agilent VistaChip II exemplifies the integration of sensitive, low-noise detection with adaptive pixel control and robust design features, enabling comprehensive multi-element analysis from trace to bulk concentrations with unmatched speed and reliability.

Used instrumentation

• Agilent 720 and 725 Series ICP-OES systems
• VistaChip II solid-state detector with 70,000 pixels and echelle optics
• Triple-stage Peltier cooling module (down to –35 °C)
• Hermetic inert-gas detector enclosure