Exploiting pi-acceptors for the determination of thyroid hormones (T3 and T4) using a single interface flow system

• Type: Article in International Scientific Journal
• Date: 2009

Authors

Cristina I C Silvestre (Author) Other; Joao L M Santos (Author) FFUP; Jose L F C Lima (Author) FFUP; Elias A G Zagatto (Author) Other

Journal

Title: Talanta

Vol. 79 No. 4

Pages: 1177-1180

ISSN: 0039-9140

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 4 Citations

Scopus - 3 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-003-FSN

DOI: 10.1016/j.talanta.2009.01.043

Abstract (EN): A fully automated methodology was developed for the determination of the thyroid hormones levothyroxine (T4) and liothyronine (T3). The proposed method exploits the formation of highly coloured charge-transfer (CT) complexes between these compounds, acting as electron donors, and pi-acceptors such as chloranilic acid (CIA) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). For automation of the analytical procedure a simple, fast and versatile single interface flow system (SIFA)was implemented guaranteeing a simplified performance optimisation, low maintenance and a cost-effective operation. Moreover, the single reaction interface assured a convenient and straightforward approach for implementing job's method of continuous variations used to establish the stoichiometry of the formed CT complexes. Linear calibration plots for levothyroxine and liothyronine concentrations ranging from 5.0 x 10(-5) to 2.5 x 10(-4) mol L(-1) and 1.0 x 10(-5) to 1.0 x 10(-4) mol L(-1), respectively, were obtained, with good precision (R.S.D. <4.6% and <3.9%) and with a determination frequency of 26 h(-1) for both drugs. The results obtained for pharmaceutical formulations were statistically comparable to the declared hormone amount with relative deviations lower than 2.1%. The accuracy was confirmed by carrying out recovery studies, which furnished recovery values ranging from 96.3% to 103.7% for levothyroxine and 100.1% for liothyronine.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 4