Interfacing on-line solid phase extraction with monolithic column multisyringe chromatography and chemiluminescence detection: An effective tool for fast, sensitive and selective determination of thiazide diuretics

A new, multisyringe flow injection set-up has been developed for the completely automated determination of trace thiazide compounds with diuretic action in different types of samples. The proposed instrumental set-up exploits for the first time, a low pressure on-line solid phase extraction–liquid chromatography–chemiluminescence detection method. This novel combination of sample treatments in flow systems expands the current applicability of low pressure liquid chromatography due to the isolation/preconcentration of the target compounds, besides high selectivity and sensitivity.For the determination of three thiazide compounds named hydroflumethiazide, furosemide and bendroflumethiazide, the proposed set-up provided with the preconcentration of only 1 mL of sample, limits of detection of 3, 60 and 40 μg L−1, respectively. Furthermore wide linear dynamic ranges of 6–4000, 140–20,000 and 90–40,000 μg L−1, respectively, were obtained. Besides of this, a high injection throughput of 12 h−1 was also achieved. As in sports, thiazide diuretics are prohibited substances, the proposed method has been applied to their determination in urine samples. Furthermore the potential of the proposed method as a fast-screening approach for emerging contaminants in waters has been also tested by applying it to well water and leachates from a solid waste landfill.