Analysis of Phenols in Drinking Water Using Triple Quadrupole LC/MS/MS (LCMS-8040)

Importance of the Topic

Phenolic compounds including phenol, chlorophenols and their derivatives often form as by-products of water disinfection and wastewater treatment. These compounds pose potential health risks and are subject to stringent water quality standards in many countries, including Japan, which regulates six phenolic species. Reliable, sensitive and rapid analytical methods are essential for monitoring trace levels of these contaminants in drinking water.

Objectives and Study Overview

This work presents the development and validation of a simplified analytical approach for quantifying six regulated phenols in drinking water using ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC-MS/MS). The goal was to eliminate the derivatization step required by conventional GC/MS methods and to demonstrate performance at sub-µg/L concentration levels.

Methodology and Instrumentation

Sample pretreatment followed the solid-phase extraction (SPE) procedure specified by regulatory notification, employing an N-containing styrene-divinylbenzene-methacrylic acid copolymer SPE cartridge (InertSep PLS-3). A 500 mL water sample was adjusted to pH 2, conditioned, loaded, washed and eluted with methanol. The extract was concentrated and brought to volume with water.

Analysis was carried out on a UHPLC-MS/MS system with the following conditions:

• Column: C18 (100 mm×2.1 mm, 3 µm)
• Mobile phases: water (A) and methanol (B), gradient from 40 % to 95 % B
• Flow rate: 0.5 mL/min, column temperature: 40 °C, injection volume: 50 µL
• Ionization: APCI negative mode (probe voltage –3.5 kV)
• Source temperatures: DL and block heater 200 °C, interface 350 °C
• Gas flows: nebulizing air 3 L/min, drying N₂ 5 L/min
• MRM transitions optimized for each analyte (e.g., phenol m/z 93.0 > 65.0)

Key Results and Discussion

Calibration curves demonstrated excellent linearity (R² > 0.9993) over an equivalent test-water concentration range of 0.008 to 1 µg/L. Repeatability at the lowest calibration point (0.008 µg/L) showed relative standard deviations below 8 %. Mass chromatograms revealed clear separation of all six phenolic compounds without interference. Spike and recovery experiments in tap water at 0.08 and 0.4 µg/L levels yielded recoveries between 102 % and 106 % at the lower level and near 100 % at the higher level, confirming method accuracy and suitability for routine monitoring.

Benefits and Practical Applications

The UHPLC-MS/MS approach eliminates derivatization, reducing sample preparation time and potential errors. The method achieves detection limits well below regulatory thresholds and offers high throughput for quality control laboratories. It is directly applicable to environmental monitoring, drinking water compliance testing and industrial QA/QC of treated water.

Future Trends and Applications

Further developments may include automation of SPE workflows, extension of the method to other phenolic and halogenated by-products, and integration with high-resolution mass spectrometry for non-target screening. Miniaturized or on-site UHPLC-MS systems could enable real-time water quality surveillance.

Conclusion

A robust UHPLC-MS/MS method was established for six regulated phenols in drinking water, providing sensitivity, accuracy and speed without the need for chemical derivatization. The validated protocol meets regulatory requirements and supports efficient water quality monitoring.

References

1. Kubota R., Kobayashi N., Tahara M., Sugimoto N., Ikarashi Y.: Investigation of the Analytical Method for Phenols and Chlorophenols in Tap Water by Solid-Phase Extraction - LC/MS; JEC 22nd Annual Conference, 2013.
2. Kubota R., Kobayashi N., Saito K., Saito N., Suzuki T., Kosugi Y., Tanaka M., Tsukamoto T., Hayashida H., Hirabayashi T., Yamamoto I., Ikarashi Y.: Validity Assessment of Phenols Investigation Method by Solid-Phase Extraction - LC/MS; JEC 23rd Annual Conference, 2014.