Developing a High Performance Liquid Chromatography Method for the Analysis of Triclosan in Surface Waters
Chemistry, Dr. Stoll
About My Research:
Finding triclosan, a common antibacterial chemical very commonly found in ordinary hand soap, in the Minnesota River was our goal for the summer. Studies like this are typically done by high performance liquid chromatography or HPLC. HLPC is a method where test samples are passed through a separation column where the target compound, triclosan, is separated from the sample by an analytical column, a tube filled with very small particles, and then the separated sample is sent on to an expensive mass spectrometer to detect the low concentration of triclosan. Our approach to this problem of triclosan detection is to do a better than average separation so we can get away with using less expensive ultra-violet light detectors. We do these better separations by using two or three additional analytical columns to separate triclosan from the water sample. The advantage to the three column system is that the columns used can have completely different separation properties. These differing properties allow compounds that are closely related to triclosan to be separated more efficiently on the additional columns. So by using a three column HPLC system we can detect triclosan in Minnesota River water at less expense than traditional methods.
Complicated sample matrices such as surface waters pose a challenging separation problem when the analysis of one target analyte is desired. This difficulty comes when multiple closely related compounds within the matrix have similar retention times on a single column used in traditional one-dimensional high performance liquid chromatography. A possible solution to this problem is the addition of multiple separation dimensions to the HPLC system. The addition of added dimensions increases complexity of the system, but allows for the use of two widely varied column chemistries to separate the target analyte from the matrix. This process is executed by a variation on the traditional heartcutting method by taking a fraction coming off the first dimension column and using the technique of hybrid slicing. This hybrid method has the first dimension peak sliced into multiple pieces. Each piece is then sent to the second dimension column for further separation. The real benefit to this slicing method is when chemometrics is applied to the data analysis. The hybrid 2D method yields a 4-dimension data set. As a means of guiding the development of this approach, we have chosen triclosan as a target analyte. Triclosan is a common antibacterial found in hand soaps, detergents and plastics, and has been shown to degrade into carcinogenic dioxins in the presence of chlorine used in many wastewater treatment facilities. The use of hybrid 2D-HPLC with chemometrics gives the ability to quantitatively separate triclosan form surface waters at much lower levels than traditional one-dimensional HPLC with UV detection.