A new strategy for highly efficient single-drop microextraction with a liquid–gas compound pendant drop

Abstract

Herein, a simple assembly was designed via a capillary and a funnel-like cap to achieve liquid-gas compound pendant drop (CPD) microextraction with great convenience. Due to the increased contact area and adhesion force between the capillary tip and the drop, the proposed method provides considerable flexibility in producing CPDs with different air bubble sizes. Four pesticides were chosen as model analytes to evaluate the proposed method. By using a 1 μL chlorobenzene droplet containing a 1 μL air bubble at a stirring rate of 700 rpm, a 70 to 135-fold enrichment of pesticides was obtained within 3.4 minutes. As compared with a typical SDME, the proposed method showed a 2-fold increase of enrichment factors and a 4-fold decrease of extraction time. Improvement of the extraction efficiency could be ascribed to the increased surface area of the droplet, and the thin film phenomena further improved the extraction kinetics through effective agitation. The results indicate that CPD microextraction could serve as a promising sample pretreatment method for automated high-throughput analyses in a wide variety of research areas.

Current overview and perspectives in environmentally friendly microextractions of carbamates and dithiocarbamates

“…This SDME enabled the determination of the carbamates and dithiocarbamates, and it still allows automatization in the extraction steps, such as the generation of the solvent drop, insertion of an air bubble, drop reacquisition by the syringe, and injection into an analytical technique. However, BIDME is directly influenced by the size of the bubble due to the surface area of the drop, which can provide instability of the extraction (Chullasat et al, 2020;Jain & Verma, 2020;Marcinkowska et al, 2019;Williams et al, 2011;Xie et al, 2014). Chullasat et al employed the BIDME to the determination of propham, chlorpropham, promecarb, carbofuran, aminocarb, pirimicarb, carbaryl, and methiocarb in water samples.…”

Present state and applications of single drop microextraction for the determination of harmful organic compounds and pollutants

“…Overview of the applicability of SDME for environmental sample analysis is shown in the Table 2. SDME was an appropriate extraction technique for liquid samples such as tap water (Kaykhaii et al 2005;Lamboropoulou et al 2007;Yohannes et al 2016), river water (Kaykhaii et al 2005;Saraji and Bankhshi 2005;Ahmadi et al 2006;De Souza Pinheiro et al 2009;De Souza Pinheiro et al 2011;Soares et al 2014;Amde et al 2015;Yohannes et al 2016), lake water (Wu et al 2008;Xie et al 2014;Amde et al 2015;Yohannes et al 2016), surface water (Lopez-Blanco et al 2003;Lamboropoulou et al 2007;Santos et al 2017), drinking water (Lopez-Blanco et al 2003;Ahmadi et al 2006;Carlos et al 2013), effluent and influent water (Amde et al 2015), ground water (Yohannes et al 2016;Santos et al 2017), water from the farm (Ahmadi et al 2006), sea water (Tian et al 2014) and other water samples (Przyjazny and Kokosa 2002). Furthermore, SDME was applied for the extraction of the pesticides from the soil samples (Salemi et al 2013;Williams et al 2014;Soares et al 2015).…”

“…Toluene, provided stable drop and avoided bubble formation during extraction according to vapour pressure lower than other solvents, was mostly used in direct immersion (DI) mode (Lamboropoulou et al 2007;De Souza Pinheiro et al 2009;De Souza Pinheiro et al 2011;Tian et al 2014;Santos et al 2017). However, the bubble formation in the drop was required for the extraction of pesticides from lake water by Xie et al (2014) by exposing the liquid-gas pendant drop (CPD) to the sample. The stability of the CPD was investigated by monitoring the formation of 1 μL organic droplets (toluene, chlorobenzene) containing different volumes of air bubble in a sample solution resulting in the better stability of the drop using chlorobenzene.…”

“…A formation of a liquid-gas CPD was performed using a novel extraction assembly consisting of a 10 mm long quartz capillary, a funnel-like PMMA cap and a 5 mL microsyringe. The limitation of droplet instability in comparison with DI-SDME was overcome, larger microdrop size and higher stirring rates could be employed, as well as liquid-gas CPD has a potential to be fully automated by using a syringe pump (Xie et al 2014). A 70-to 135-fold enrichment of pesticides was obtained.…”

“…The volume of the drop was in the range of 0.9 μL (Ahmadi et al 2006) and 10 μL (Wu et al 2007;Amde et al 2015). Drop volume 1 μL was the most frequently applied, what can be explain by the found consensus between the volume, stability and extraction capacity of the drop (Kaykhaii et al 2005;De Souza Pinheiro et al 2009;De Souza Pinheiro et al 2011;Williams et al 2014;Xie et al 2014;Santos et al 2017). Sampling repeatability of the microdrop requires the use of the proper syringe needle for the extraction.…”