Determination of Bisphenol A in Drinking Water Using the Wayeal LCMS-TQ9200 LCMS/MS

Bisphenol A (BPA), a chemical widely used in the production of polycarbonate plastics and epoxy resins, is quietly present in numerous everyday items—from mineral water bottles and food can linings to shopping receipts. However, this material, which brings convenience, has been confirmed by research to be a potential endocrine disruptor due to its chemical structure being similar to that of human estrogen. Long-term or excessive exposure may interfere with normal hormonal functions, posing potential risks to childhood development, reproductive health, and even the metabolic system. To safeguard public health and environmental safety, strict regulatory frameworks for bisphenol A have been established worldwide. In China, the "Standards for Drinking Water Quality" (GB 5749-2022) stipulates that its content shall not exceed 0.01mg/L, and stringent limits are also imposed on food contact materials and other relevant products. Accurate determination of bisphenol A at these trace levels is the key to effective regulation.

In this experiment, the Wayeal LCMS-TQ9200 liquid chromatography-tandem mass spectrometry system was used to determine the content of bisphenol A in drinking water. The experimental results showed that in the system suitability test, the peak shape was satisfactory and the linearity was good, meeting the requirements of the experiment. For the bisphenol A standard working solution, six consecutive injections yielded a retention time deviation of less than 1% and a peak area deviation of less than 5%, demonstrating good repeatability. The test results for all samples were normal. All the above data meet the requirements for the qualitative and quantitative detection methods for bisphenol A.

Keywords: Liquid chromatography-tandem mass spectrometry; bisphenol A; drinking water; water quality safety.

1. Instruments and Reagents

1.1 LC-MS/MS Configuration List

Table 1. Instrument configuration list

1.2 Reagents and Standards List

Table 2. Reagents and standards list

1.3 Experimental Materials and Auxiliary Equipment

Ultrasonic cleaner;

Vortex mixer;

High-speed centrifuge.

2. Experiment Method

2.1 Sample Pretreatment

A solid-phase extraction (SPE) cartridge was conditioned successively with 5mL of methanol and 5mL of purified water. A 100mL water sample was then passed through the SPE cartridge at a flow rate of 3–5mL/min. After loading was complete, the residual moisture in the cartridge was drained. The analytes were eluted with 10mL of methanol in two portions, with the eluent flow rate controlled at approximately 1 drop per 3 seconds. The eluate was collected in a glass test tube and evaporated to near dryness under a stream of nitrogen in a 50 °C water bath. The residue was reconstituted to 1.0 mL with 50% methanol solution, vortex-mixed, and then ready for analysis.

When the concentration of bisphenol A in the water sample is high, direct injection analysis may be employed.

2.2 Experiment Conditions

2.2.1 HPLC Conditions

Chromatographic column: C18, 2.6μm, 2.1 × 100mm;

Mobile phase: Phase A: 0.1% ammonium hydroxide solution; Phase B: methanol;

Flow rate: 0.3mL/min;

Column temperature: 40 °C;

Injection volume: 3µL.

2.2.2 Mass Spectrometer Conditions

Table 3. Mass Spectrometry Ion Source Parameters

3. Experiment Result

3.1 System Suitability Test

The system suitability test results showed that the target peak showed a good peak shape with no interfering peaks in the vicinity, meeting the experiment requirements.

Fig 1 Chromatogram of bisphenol A standard working solution (5ng/mL)

3.2 Linear Range

A bisphenol A standard solution was used to prepare the calibration curve stepwise with intermediate concentration working solutions. The linear range of bisphenol A was 0.5–100ng/mL, with an R² greater than 0.999, indicating a good linear relationship.

Table 4. Linear Range of Bisphenol A

Fig 2. Standard calibration curve of bisphenol A

3.3 Limit of Detection and Limit of Quantification

In this method, 0.2ng/mL and 0.5ng/mL were used as the limit of detection (LOD) and limit of quantification (LOQ) for the bisphenol A standard solution, respectively. The corresponding signal-to-noise ratios were 29.39 and 86.38, which are greater than 3 and 10, respectively, meeting the sensitivity requirements of the experiment.

Table 5. Limits of Detection and Limits of Quantification for the Compound

Fig 3. Ion current chromatograms of bisphenol A at the LOD and LOQ

3.4 Precision Test

Bisphenol A solutions at three concentration levels (low, medium, and high) were prepared. Each solution was injected six consecutively to compare the deviations in retention time and peak area. The results are shown in the table below. The retention time deviation of bisphenol A was less than 1%, and the peak area deviation was less than 5%, meeting the requirements of the experiment.

Table 6 Precision Test for Bisphenol A

Fig 4 Chromatograms of Bisphenol A Precision Test at Low, Medium, and High Concentrations (n=6)

3.5 Sample Test

Appropriate amounts of commercially available purified water and municipal tap water were taken and tested according to the pretreatment method described above. After sample injection and analysis, bisphenol A was not detected in either type of water.

Fig 5. Chromatogram of Bisphenol A in a Commercially Available Purified Water Sample

Fig 6 Chromatogram of Bisphenol A in a Municipal Tap Water Sample

4. Conclusion

This method employs the Wayeal LCMS-TQ9200 liquid chromatography-tandem mass spectrometry system for the determination of bisphenol A content in drinking water.

The experiment data demonstrate that this method produces chromatographic peaks with good symmetry and no tailing. The sensitivity meets the experimental requirements, and the linear correlation coefficient is greater than 0.999. For six consecutive injections, the retention time deviation for each compound was less than 1% and the peak area deviation was less than 5%, indicating good precision. No bisphenol A was detected in either the commercially available purified water or the municipal tap water samples.