Determination of nitrophenols using ultrahigh pressure liquid chromatography and a new manual shaking-enhanced, ultrasound-assisted emulsification microextraction method based on solidification of a floating organic droplet

Nitrophenols are toxic compounds in the wastewater. In the proposed method, a new technique using a manual shaking-enhanced, ultrasound-assisted emulsification microextraction (MS-USAEME) method based on solidification of a floating organic droplet combined with ultrahigh pressure liquid chromatography (UHPLC) has been developed for the extraction and determination of nitrophenols in aqueous samples. In this method, the low toxicity extraction solvent 1-undecanol was used to extract the nitrophenols. After centrifugation, ice bath was used to solidify the floating extraction solvent, using microtubes to collect the floated extraction solvent and diluting with 30 μL of dimethyl sulfoxide, then injecting into the UHPLC for further analysis. The relative standard deviations (RSD) were 6–12%, enrichment factors (EFs) were 62–500, the relative recoveries (RR) of this method were 80–110% for spiked lake water samples. The detection limits of this method were 0.5–3.0 μg L−1 for spiked lake water and 0.6–3.2 μg L−1 for spiked agriculture water. The further performance of the proposed method was gauged by analyzing field samples.

► Only 12 μL of low toxic organic solvent is required.
► Low LODs, fast extraction.
► Manual shaking for 10 s before ultrasound emulsification is essential.
► Method based on solidification of a floating organic droplet is used.