Ultra-high-performance liquid chromatography (UHPLC) coupled with a cobalt phthalocyanine screen-printed carbon electrode (CoPc-SPCE) was developed
and validated for quantitative analysis of ethylenethiourea (ETU) and propylenethiourea (PTU). CoPC-SPCE provided high catalytic properties for ETU and
PTU oxidation. This fabricated electrode is inexpensive, disposable, and easy to prepare by an in-house screen-printing technique. The chromatographic
separation was performed in isocratic mode on a reversed phase C18 (100 mm x 4.6 mm, 3 mu m) column, using a 90 : 10 (v/v) ratio of 0.05 M phosphate
buffer solution (pH 4) and methanol as the mobile phase with a flow rate of 1.0 mL min(-1)at an oxidation potential of +0.7 Vvs.Ag/AgCl. The separation could
be achieved within 3 min, and a wide linear range of 0.01-100 mu g mL(-1)(r(2)> 0.99) was obtained for both analytes. The limits of detection (3 S/N) were
found to be 0.006 and 0.009 mu g mL(-1)for ETU and PTU, respectively. Furthermore, this proposed method was utilized to determine ETU and PTU in fruit
samples with satisfactory results, yielding excellent intra-day and inter-day relative standard deviations and recoveries. These results demonstrated that the
proposed assay can be used as a new alternative way for inexpensive, rapid, selective and sensitive determination of ETU and PTU in fruit samples.