Department of Analytical Chemistry, Faculty of Chemistry, Oles Honchar Dnipro National University, Dnipro, Ukraine.
Department of Analytical Chemistry, Institute of Chemistry, Faculty of Science, Pavol Jozef Šafárik University in Košice, Košice, Slovak Republic.
PLoS One. 2024 Aug 19;19(8):e0309121. doi: 10.1371/journal.pone.0309121. eCollection 2024.
The combination of an optical probe and single-drop direct immersion microextraction (DI-SDME-OP) was used for the preconcentration and subsequent spectrophotometric determination of rhodamine 6G (Rh6G). The developed method is based on the formation of an ionic associate between Rh6G and picric acid at pH 3.0 and its extraction with amyl acetate. A microdrop of the organic phase was stably placed in the hole of an optical probe immersed in the sample solution. The absorbance of the extraction phase was monitored at 534 nm. The proposed method combines in a single step several stages of the analytical procedure, such as pre-concentration, phase separation, transfer of the extraction phase to the instrument and online measurement. The sensitivity of the proposed approach is not inferior to existing microextraction methods involving the combination of liquid-phase or solid-phase extraction with spectrophotometry or HPLC with a UV-Vis detector. The evaluation of the greenness of the developed method carried out by the AGREE method (0.58 points) showed that it outperforms other similar existing techniques using this parameter. The calibration plot for the determination of Rh6G by the DI-SDME-OP method was linear over the range of 10-500 nM with a correlation coefficient of 0.9956. The limit of detection was 3.4 nM. The accuracy and applicability of the method were evaluated by the determination of Rh6G in natural waters and lipstick.
光学探针与单滴直接浸入微萃取（DI-SDME-OP）结合用于罗丹明 6G（Rh6G）的预浓缩和随后的分光光度测定。所开发的方法基于 Rh6G 与苦味酸在 pH 3.0 下形成离子缔合物，并用乙酸戊酯萃取。将有机相的微滴稳定地放置在浸入样品溶液中的光学探针的孔中。监测萃取相在 534nm 处的吸光度。该方法将分析程序的几个阶段（如预浓缩、相分离、萃取相转移到仪器和在线测量）组合在一个步骤中。该方法的灵敏度不低于涉及液相或固相萃取与分光光度法或 HPLC 与紫外可见检测器相结合的现有微萃取方法。通过 AGREE 方法（0.58 分）对开发方法的绿色度进行评估表明，它在使用该参数的其他类似现有技术方面表现出色。通过 DI-SDME-OP 方法测定 Rh6G 的校准曲线在 10-500nM 范围内呈线性，相关系数为 0.9956。检测限为 3.4nM。通过测定天然水和口红中的 Rh6G 来评估该方法的准确性和适用性。
