Development of a sample enrichment probe method for the gas chromatography-mass spectrometry analysis of hormones in water

A simple sample enrichment probe (SEP) sampling method was developed for the determination of endogenous steroid hormones (estrone, I 7P-estradiol and testosterone) in water using gas chromatography-mass spectrometry (GC-MS). SEPs constructed of thin stainless steel rods of inert material or sections of a polyimide coated megabore GC column provided at one end with a short sleeve of polydimethylsiloxane (PDMS) rubber as the sorbent material were used. The selected target hormones were estrone, I 7P-estradiol and testosterone. Extraction of the steroid hormones was performed by direct immersion of the SEP in water samples. To maximise the extraction efficiency of the SEP method to extract the analytes, several parameters affecting the extraction efficiency of the SEP method, such as extraction time, extraction temperature, pH and ionic strength were optimised. Due to challenges encountered with the GC-MS the method was only partially validated using ultra-pure water samples spiked with hormones at different concentration levels. Under the optimal conditions, the method showed satisfactory linearity over a concentration range of 1-10 μg/mL (for estrone and testosterone) and 2-10 μg/mL (for estradiol), with regression squares (R2) ranging between 0.988-0.996. Acceptable reproducibility in the range of 2-17 % RSD was achieved. The obtained limits of quantitation (LOQs) were 0.5 μg/mL for the three steroids. Although the SEP-GC-MS method gave very high LOQs when compared to existing SPME and SBSE methods, it proved to be a simple and cost-effective alternative to these methods.

Grantor dc:publisher

University of Namibia

Year dc:date.issued

2019

Author dc:creator

• Karumendu, Ivondia

• Chromatography-mass spectrometry
• Polydimethylsiloxane
• Steroid hormones

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/11070/3218

OAI identifier oai:identifier

oai:repository.unam.edu.na:11070/3218