Triclosan is a chemical that has been used as an antibacterial agent in many soaps and a variety of other consumer and personal care products for many years. Because of its widespread use and high production volume (exceeding 1 million pounds annually based on a 1998 U.S. EPA assessment), the US FDA is involved in “scientific and regulatory review of this ingredient”. In 2003-2004, the US Centers for Disease Control detected the chemical in the urine of 75% of people tested. Recent animal studies have shown that triclosan is a potential endocrine disruptor. With regard to the impact of triclosan on the environment, monitoring programs found the chemical in many tested streams, where it is introduced through the discharge of wastewater treatment plants. Triclosan was included in EPA Method 1694 developed for the measurement of pharmaceutical and personal care products by LC/MS/MS.
In this study, triclosan was detected in the environmental samples of local water using Supel™-Select HLB polymeric SPE for cleanup and an Ascentis® Express C18 HPLC column for detection.
The water samples were collected from the discharge of the local wastewater treatment plant. The samples were also collected from the creek about 400 yards below the discharge location.
The method was developed by adapting standard EPA method 1694 for analysis of triclosan and using Supel-Select HLB SPE cartridges (Cat. No. 54182-U). The modifications to method 1694 included introduction of an alternate elution solvent -- 1:1 acetonitrile:methanol. It was better suited for elution of the analyte from the HLB cartridge. The sample loading volume was reduced to 50 mL from 500 mL and the elution volume was reduced to 3 mL instead of 6 mL used in the standard method. The final methodology for detection of triclosan is presented in Figure 1.
Both UV and MS/MS detection methods were tested for the environmental water samples. Higher concentration of triclosan in the wastewater plant eluent enabled its detection by UV while lower concentration of triclosan in the stream required MS/MS detection for accurate quantitation. The HPLC method was developed using Ascentis Express C18 HPLC column. The Fused-Core® technology provided good resolution of triclosan peak from the background peaks in the samples, resulting in sharper peaks and lower limits of detections for triclosan. The Ascentis Express columns allowed the separation to be run at low backpressure using existing HPLC instruments (Agilent® 1200 and Agilent 1100 stacks were used).
Figure 1. Sample preparation method for analysis of water samples for triclosan using Supel-Select HLB SPE 60 mg/3 mL (54182-U).
Figure 2 shows the resulting UV chromatograms of water samples.
Figure 3 shows the MS/MS chromatograms for the same water samples.
Figure 2. UV chromatograms of triclosan in water at 280 nm.
CONDITIONS: column: Ascentis Express C18, 15 cm x 2.1 mm I.D., 2.7 µm (53825-U); mobile phase: 40% methanol, 40% acetonitrile, 20% potassium phosphate tribasic, pH 2.5; flow rate: 0.150 mL/min; temperature: 30 °C; detector: UV 280 nm; column pressure: 112 bar; injection: 10.0 µL; instrument: Agilent 1200 Series HPLC-UV
Figure 3. LC/MS/MS chromatograms of triclosan in water.
CONDITIONS: column: Ascentis Express C18, 15 cm x 2.1 mm I.D., 2.7 µm (53825-U); mobile phase: 40% methanol, 40% acetonitrile, 20% aqueous 0.1% formic acid; flow rate: 0.150 mL/min; temp.: 30 °C; detector: Q1/Q3 286.8/35.0 ESI negative; injection: 10.0 µL; instrument: Agilent 1100/1200 HPLC and AB SCIEX QTRAP® 3200
Limit of detection for triclosan by UV method was estimated at 100 ng/L when using 50 mL loading water sample. EPA method 1694 specified the detection limit for triclosan as 94 ng/L using 500 mL loading SPE volume and MS/MS detection. The use of Ascentis Express column resulted in sharper peaks and allowed the low detection limit to be met using less sensitive UV detection technique.
The concentration of triclosan in the sample from wastewater plant was found to be high at about 1000 ng/L. This concentration was easily detectable by UV method. MS/MS method confirmed that the UV method provided correct concentration result.
In the samples taken 400 yards downstream, the triclosan levels were further diluted by the creek water, producing results that were below the detection limits for the UV method. The MS/MS methodology allowed the detection of triclosan in the creek below the discharge from wastewater treatment plant. The detection limit for triclosan by MS/MS method was estimated to be 50 ng/L when using 50 mL water sample.
A method for detection of triclosan in environmental water samples was developed using Supel Select SPE cleanup and convenient 50 mL loading sample volume. A Fused-Core Ascentis Express C18 HPLC column allowed sharper peaks, lower detection limits with low backpressure and was used in existing HPLC systems. The triclosan was detected in the wastewater plant discharge by both UV and MS/MS methods at about 1000 ng/L. Triclosan was present in creek water at 63 ng/L and at this level required MS/MS detection.
Fused-Core is a registered trademark of Advanced Materials Technology Inc.
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