High-Performance Liquid Chromatography (Hplc) for the Analysis of Polycyclic Aromatic Hydrocarbons (Pahs) in Water

Abstract: A solid-phase extraction coupled with high-performance liquid chromatography (HPLC) was used to determine PAHs in water. A Supelco solid-phase extraction filtration system and a Supelco C18 solid-phase extraction column were used, with 100% methanol as the mobile phase.

Keywords: Polycyclic aromatic hydrocarbons; Solid-phase extraction; High-performance liquid chromatography

PAHs, represented by benzo[a]pyrene, are among the most important environmental pollutants to monitor, and their monitoring has received increasing attention. The concentration of PAHs in natural water ranges from 0.001 to 10 μg/L, while in industrial wastewater it can reach as high as 1 mg/L. my country's drinking water standards stipulate that the content of 3,4-benzo[a]pyrene in water should be less than 0.01 μg/L, while the World Health Organization has set the maximum acceptable concentration of six representative PAHs in drinking water at 0.02 μg/L. The key to analyzing PAHs in water lies in enriching PAHs in the water and separating trace amounts of PAHs from other organic matter. Traditional fluorescence spectrophotometry for the determination of benzo[a]pyrene is not only unsafe but also cumbersome and time-consuming. This paper establishes a more comprehensive method for analyzing polycyclic aromatic hydrocarbons (PAHs) in water using advanced solid-phase extraction (SPE) pretreatment technology and high-performance liquid chromatography (HPLC).

1. Experimental Section

1.1 Instruments and Reagents

Pekin Elmer Integral 4000 liquid chromatograph (equipped with a diode array detector and autosampler), PE LC-240 fluorescence detector, Supelco solid-phase extraction filtration system, Supelco 3 ml C18 solid-phase extraction column.

CH3OH (chromatographic grade), ultrapure water, CH2Cl2 (chromatographic grade), Supelco PAH standard solution. Simulated water samples were prepared from PAH standard solution and ultrapure water.

1.2 Chromatographic Conditions

A Supelco 4.6 mm × 250 mm PAHs-specific column was used with CH3OH as the mobile phase at a flow rate of 2.0 mL/min. For FLU, BbF, BkF, and Bper, the excitation and emission wavelengths were 286.0 nm and 430.0 nm, respectively. For IP, the excitation and emission wavelengths were 300.0 nm and 500.0 nm, respectively. The column temperature was controlled at 30.0 °C during detection.

1.3 Sample Pretreatment

500 mL of water sample was taken and allowed to pass completely through the SPE column at a flow rate of approximately 4–5 mL/min. Then, 5 mL of pure water was added to the column and allowed to pass slowly. Air was purged for 1 min, followed by nitrogen purging for 30 min to thoroughly dry the SPE column. 2 mL of CH2Cl2 was added to the column in two portions. The combined eluent was concentrated to 0.5 mL with nitrogen for analysis.

2. Results and Discussion

2.1 Standard Curves

The lowest concentrations of FLU, BbF, BkF, Bper, and IP in the five mixed standard solutions prepared in the experiment were 20.0, 8.0, 8.0, 32.0, and 20.0 ug/L, respectively, and the highest concentrations were 100.0, 40.0, 40.0, 160.0, and 100.0 ug/L, respectively. The correlation coefficients of the standard curves for the five PAHs were all better than 0.999.

2.2 Precision and Recovery

The first mixed standard solution was diluted 1000 times with ultrapure water. The precision and recovery rates of the five PAHs were determined and are shown in Table 1. Except for IP, which had poor precision, the precision and recovery rates of the other four PAHs were satisfactory. The detection limits of the method for FLU, BbF, BkF, Bper, and IP were 4.1, 3.8, 1.6, 14.4, and 3.8 ng/L, respectively.

2.3 Determination of Actual Water Samples Figure 1 shows the chromatogram of an actual water sample. The detection peaks of FLU, BbF, BkF, and Bper are clearly visible in the figure; the peaks obtained in the experiment were weaker, possibly due to the low concentration of IP. Nevertheless, the method described in this paper has shown good application prospects in the detection of PAHs in actual water samples.

References

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