Introduction
Water safety is a critical issue for human health and the ecological environment. Environmental monitoring agencies need to regularly test various pollutants in surface water, groundwater, and drinking water sources. Among the national standards such as "Environmental Quality Standards for Surface Water" (GB 3838-2002) and "Standards for Drinking Water Quality" (GB 5749-2022), multiple indicators use UV-Vis spectrophotometry as the standard analytical method.
UV-Vis spectrophotometry has become an indispensable analytical tool in environmental monitoring laboratories due to its simple operation, low cost, rapid analysis, and excellent reproducibility.
Determination of Nutrients in Water
Ammonia Nitrogen:
Ammonia nitrogen is a key indicator for evaluating water pollution levels. The Nessler's reagent spectrophotometric method (HJ 535-2009) is a national standard method. Under alkaline conditions, ammonia reacts with potassium mercuric iodide to form a yellow-brown complex, measured at 420nm. The NanoQuant series spectrophotometers offer excellent stability and low stray light (≤0.1%T), ensuring accurate determination of low-concentration ammonia nitrogen.
Total Phosphorus:
Excess phosphorus in water is a major contributor to eutrophication. In the ammonium molybdate spectrophotometric method (GB 11893-89), phosphate reacts with ammonium molybdate under acidic conditions to form phosphomolybdic heteropoly acid, reduced by ascorbic acid to a blue complex measured at 700nm.
Nitrate Nitrogen:
UV spectrophotometry (HJ/T 346-2007) directly measures nitrate ions by their characteristic absorption at 220nm. The NanoQuant756/1810/1920 series offer excellent optical performance in the deep UV range (190-230nm), enabling rapid nitrate nitrogen screening.
Heavy Metal Detection in Water
Using chromogenic reagents that form colored complexes with metal ions, UV-Vis spectrophotometry can indirectly determine various heavy metals:
- Hexavalent Chromium: Diphenylcarbazide spectrophotometric method (GB 7467-87), measured at 540nm, detection limit 0.004mg/L
- Copper: Sodium diethyldithiocarbamate spectrophotometric method, measured at 440nm
- Iron: 1,10-Phenanthroline spectrophotometric method, measured at 510nm
- Manganese: Permanganate oxidation method, measured at 525nm
Determination of Other Pollutants
Volatile Phenols: 4-Aminoantipyrine spectrophotometric method (HJ 503-2009), measured at 510nm.
Anionic Surfactants: Methylene blue spectrophotometric method (GB 7494-87), measured at 652nm.
Fluoride: Alizarin complexone spectrophotometric method (HJ 488-2009), measured at 620nm.
Sulfide: Methylene blue spectrophotometric method (HJ 1226-2021), measured at 665nm.
Advantages of STON Spectrophotometers
STON Technologies' NanoQuant series UV-Vis spectrophotometers offer comprehensive solutions for environmental monitoring:
- NanoQuant1810 Ratio Dual-Beam: 1600 lines/mm holographic grating, stray light ≤0.03%T, 8-inch touch screen, GLP self-verification with auto-report generation
- NanoQuant1920 Double Beam: 5 selectable slit widths (0.5/1/2/4/5nm), scanning speed up to 4100nm/min, baseline flatness ±0.0005A, ideal for demanding environmental analysis
- NanoQuant756: Wavelength range 190-1100nm, wavelength accuracy ±0.5nm, cost-effective for routine environmental testing
Conclusion
UV-Vis spectrophotometry plays an irreplaceable role in environmental water quality testing. The STON NanoQuant series spectrophotometers provide reliable analytical tools for environmental monitoring laboratories with their excellent optical performance, stable data output, and user-friendly operation.
