The aim of the work was to establish two methods for the analysis of 4 thyroid hormones and 18 plant toxins by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using electrospray ionisation (ESI). The developed and validated methods were then applied to samples, with a range of complex matrices, namely serum, simulated gastro-intestinal fluid, tablet formulation and plants, with sample preparation methods developed and validated for each.
Thyroid disorders, hypothyroidism and hyperthyroidism, are a common medical condition with diagnosis obtained via the analysis of thyroid hormones present within serum samples. Currently within the NHS analysis is performed using electrochemiluminescence to measure thyroid stimulating hormone, thyroxine and triiodothyronine. However, these methods have limited sensitivity and inaccuracies of 30% at the limit of detection. Therefore, diagnosis of hypothyroidism can often be missed with multiple medical visits being required. The developed method allows for the detection and qualification of 4 thyroid hormones, thyroxine, triiodothyronine, reverse triiodothyronine and diiodothyronine, using low resolution and high resolution mass spectrometry. The developed method showed significant improvements over the current NHS method with LOQs of 0.990 and precision of 0.9952 and precision of