Development of a low-cost method of analysis for the qualitative and quantitative analysis of butyltins in environmental samples

Abstract

Most analytical methods for butyltins are based on high resolution techniques with complicated sample preparation. For this study, a simple application of an analytical method was developed using High Performance Liquid Chromatography (HPLC) with UV detection. The developed method was studied to determine tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) in sediment and water samples. The separation was performed in isocratic mode on an ultra cyanopropyl column with a mobile phase of hexane containing 5% THF and 0.03% acetic acid. This method was confirmed using standard GC/MS techniques and verified by statistical paired t-test method. Under the experimental conditions used, the limit of detection (LOD) of TBT and DBT were 0.70 and 0.50 μg/mL, respectively. The optimised extraction method for butyltins in water and sediment samples involved using hexane containing 0.05–0.5% tropolone and 0.2% sodium chloride in water at pH 1.7. The quantitative extraction of butyltin compounds in a certified reference material (BCR-646) and naturally contaminated samples was achieved with recoveries ranging from 95 to 108% and at %RSD 0.02–1.00%. This HPLC method and optimum extraction conditions were used to determine the contamination level of butyltins in environmental samples collected from the Forth and Clyde canal, Scotland, UK. The values obtained severely exceeded the Environmental Quality Standard (EQS) values. Although high resolution methods are utilised extensively for this type of research, the developed method is cheaper in both terms of equipment and running costs, faster in analysis time and has comparable detection limits to the alternative methods. This is advantageous not just as a confirmatory technique but also to enable further research in this field.

Keywords:

• Tributyltin
• dibutyltin
• monobutyltin
• butyltins
• normal phase HPLC
• Forth and Clyde canal
• EQS values

Acknowledgments

This work was valuable supported by Center of Excellence for Innovation in Chemistry (PERCH-CIC), Kasetsart University, Bangkok, Thailand and Thames Restek UK Ltd.

Notes

∗Number of times higher than EQS values