947 Professional UV/VIS Detector, 943 Reactor, 943 Thermostat Vario

Importance of the Topic

The ability to detect and quantify ions and organic substances in complex matrices is central to quality control, environmental monitoring and industrial process analysis. Ultraviolet/visible (UV/VIS) detection in ion chromatography (IC) presents an attractive alternative to conductivity detection by exploiting specific absorption properties of many analytes. When combined with pre- or post-column derivatization, UV/VIS-active dye formation further extends the range of detectable species, enabling trace-level determination of metal ions, anions and organic compounds in water, biological fluids and industrial effluents.

Objectives and Study Overview

This application note introduces Metrohm’s 947 Professional UV/VIS Detector Vario and its intelligent reactor and thermostat modules (943 Professional Reactor Vario, 943 Professional Thermostat Vario). The goal is to demonstrate how this modular detector system can be configured for single-wavelength (SW) or multi-wavelength (MW) operation and combined with derivatization reactors to achieve high-precision quantification of challenging analytes such as chromium(VI), silicate, nitrite/nitrate and bromate at trace levels.

Used Instrumentation

• 947 Professional UV/VIS Detector Vario (SW or MW), diode array detection, 190–900 nm, 1–50 nm bandwidth, long-life UV and VIS lamps
• 943 Professional Reactor Vario, heatable pre-/post-column reactor up to 150 °C
• 943 Professional Thermostat Vario, column compartment with stable temperature control up to 80 °C
• Additional extension modules: 942 ONE/Deg for suppression, MagIC Net software for data acquisition

Methodology

The 947 Detector features a PEEK flow cell and user-selectable lamps, allowing direct detection of UV/VIS-absorbing ions or indirect detection via color-forming reactions. For post-column derivatization, reagents such as 1,5-diphenylcarbazide (for Cr(VI)) or molybdate (for silicate) are introduced in a heated reactor. The multi-wavelength detector can record full spectra, automatically identify up to eight absorption maxima and facilitate method development. Leak detection and analog output options support unattended operation and integration into automated IC workflows.

Main Results and Discussion

– Trace chromium(VI) in tap water: Post-column derivatization with diphenylcarbazide at 150 °C enabled reliable quantification at 0.025 µg/L on a Metrosep A Supp 17 column, wavelength 538 nm.
– Silicate and standard anions in boiler feed water: Molybdate reaction in the reactor allowed simultaneous determination of silicate at low µg/L alongside chloride, sulfate and other anions at 346 nm.
– Nitrite, nitrate and bromide in artificial seawater: UV detection at 218 nm separated 0.5 mg/L nitrite and 10 mg/L nitrate from a 28 g/L NaCl matrix, overcoming conductivity overlap.
– Bromate in tap water: Triiodide derivatization at 45 °C detected 0.17 µg/L bromate below regulatory limits using a Metrosep A Supp 16 column at 352 nm.

Benefits and Practical Applications

The Vario detector series offers:

• Enhanced selectivity through wavelength choice and derivatization chemistry
• Low detection limits in complex matrices without extensive sample prep
• Flexible method development using diode array spectra and multiple channels
• Modular reactor/thermostat integration for controlled reaction conditions
• Seamless interchangeability with other Metrohm IC detectors

Applications span environmental water analysis, pharmaceutical quality control, food and beverage testing, and process monitoring in power plants or chemical production.

Future Trends and Opportunities

Advances in reagent chemistries and microfluidic reactor designs will drive further sensitivity improvements and reagent consumption reduction. Intelligent control software and machine learning–assisted method optimization will accelerate development of selective derivatization protocols. Integration with online sampling systems and cloud-based data analysis will facilitate real-time monitoring of trace contaminants and reactive species in industrial and environmental settings.

Conclusion

Metrohm’s 947 Professional UV/VIS Detector Vario, in conjunction with the intelligent Reactor and Thermostat Vario modules, provides a versatile and sensitive platform for UV/VIS detection in ion chromatography. Its modular architecture, broad wavelength range and compatibility with derivatization chemistries enable reliable quantification of a wide spectrum of inorganic and organic analytes at trace levels, meeting the needs of diverse analytical challenges.

References

No references provided.