Headspace Single-drop Microextraction Method Research Articles

Water as a green solvent for sustainable sample preparation: single drop microextraction of N-nitrosamines from losartan tablets.

Water, renowned for its sustainability and minimal toxicity, is an ideal candidate for environmentally friendly solvent-based microextraction. However, its potential as an extractant solvent in miniaturized sample preparation remains largely unexplored. This paper pioneers using water as the extraction solvent in headspace single-drop microextraction (HS-SDME) for N-nitrosamines from losartan tablets. Autonomous HS-SDME is executed by an Arduino-controlled, lab-made Cartesian robot, using water for the online preconcentration of enriched extracts through direct injection into a column-switching system. Critical experimental parameters influencing HS-SDME performance are systematically explored through univariate and multivariate experiments. While most previously reported methods for determining N-nitrosamines in pharmaceutical formulations rely on highly selective mass spectrometry detection techniques to handle the strong matrix effects typical of pharmaceutical samples, the water-based HS-SDME method efficiently eliminates the interfering effects of a large amount of the pharmaceutical active ingredient and tablet excipients, allowing straightforward analysis using high-performance liquid chromatography with ultraviolet detection (HPLC-UV-Vis). Under optimized conditions, the developed method exhibits linear responses from 100 to 2400ngg-1, demonstrating appropriate detectability, precision, and accuracy for the proposed application. Additionally, the environmental sustainability of the method is assessed using the AGREEprep methodology, positioning it as an outstanding green alternative for determining hazardous contaminants in pharmaceutical products.

Smartphone Nanocolorimetric Determination of Hydrogen Sulfide in Biosamples after Silver–Gold Core–Shell Nanoprism-Based Headspace Single-Drop Microextraction

In this work, the sensitive detection of hydrogen sulfide (H2S) was realized at low cost and high efficiency through the application of silver-gold core-shell nanoprism (Ag@Au-np) combined with headspace single-drop microextraction (HS-SDME). After SDME, smartphone nanocolorimetry (SNC), with the aid of a smartphone camera and color picker software, was used to detect and quantify the H2S. The method took advantage of the inhibition of the ultraviolet-visible (UV-vis) signal caused by H2S etching of the Ag@Au-np preadded to the SDME solvent to measure the H2S concentration. The coating of the gold layer not only ensured the high stability of the nanomaterial but also enhanced the selectivity toward H2S. The HS-SDME method was simple to process and required only a droplet of solvent for analysis to be realized. This HS-SDME-SCN approach exhibited a calibration graph linearity of between 0.1 and 100 μM and a limit of detection of 65 nM (relative standard deviations of N% ( n = 3) < 4.80). A comparison with UV-vis spectrophotometry was conducted. The practical applicability of HS-SDME-SNC was successfully demonstrated by determining H2S in genuine biosamples (egg and milk).

Enhanced headspace single drop microextraction method using deep eutectic solvent based magnetic bucky gels: Application to the determination of volatile aromatic hydrocarbons in water and urine samples.

A facile headspace single drop microextraction method was developed using deep eutectic solvent-based magnetic bucky gel as the extraction solvent for the first time. The hydrophobic magnetic bucky gel was formed by combining choline chloride/chlorophenol deep eutectic solvent and magnetic multiwalled carbon nanotube nanocomposite. Magnetic susceptibility, high viscosity, high sorbing ability, and tunable extractability of organic analytes are the desirable advantages of the prepared gel. Using a rod magnet as a suspensor in combination with the magnetic susceptibility of the prepared gel resulted in a highly stable droplet. This stable droplet eliminated the possibility of drop dislodgement. The prepared droplet made it possible to complete the extraction process in high temperatures and elevated agitation rates. Furthermore, using larger micro-droplet volumes without any operational problems became possible. These facts resulted in shorter sample preparation time, higher sensitivity of the method, and lower detection limits. Under the optimized conditions, an enrichment factor of 520-587, limit of detection of 0.05-0.90ng/mL, and linearity range of 0.2-2000ng/mL (coefficient of determination=0.9982-0.9995) were obtained. Relative standard deviations were<10%. This method was successfully coupled with gas chromatography and used for the determination of benzene, toluene, ethylbenzene, and xylene isomers as harmful volatile organic compounds in water and urine samples.

Headspace single drop microextraction versus dispersive liquid-liquid microextraction using magnetic ionic liquid extraction solvents

A headspace single drop microextraction (HS-SDME) method and a dispersive liquid-liquid microextraction (DLLME) method were developed using two tetrachloromanganate ([MnCl42-])-based magnetic ionic liquids (MIL) as extraction solvents for the determination of twelve aromatic compounds, including four polyaromatic hydrocarbons, by reversed phase high-performance liquid chromatography (HPLC). The analytical performance of the developed HS-SDME method was compared to the DLLME approach employing the same MILs. In the HS-SDME approach, the magnetic field generated by the magnet was exploited to suspend the MIL solvent from the tip of a rod magnet. The utilization of MILs in HS-SDME resulted in a highly stable microdroplet under elevated temperatures and long extraction times, overcoming a common challenge encountered in traditional SDME approaches of droplet instability. The low UV absorbance of the [MnCl42-]-based MILs permitted direct analysis of the analyte enriched extraction solvent by HPLC. In HS-SDME, the effects of ionic strength of the sample solution, temperature of the extraction system, extraction time, stir rate, and headspace volume on extraction efficiencies were examined. Coefficients of determination (R2) ranged from 0.994 to 0.999 and limits of detection (LODs) varied from 0.04 to 1.0μgL−1 with relative recoveries from lake water ranging from 70.2% to 109.6%. For the DLLME method, parameters including disperser solvent type and volume, ionic strength of the sample solution, mass of extraction solvent, and extraction time were studied and optimized. Coefficients of determination for the DLLME method varied from 0.997 to 0.999 with LODs ranging from 0.05 to 1.0μgL−1. Relative recoveries from lake water samples ranged from 68.7% to 104.5%. Overall, the DLLME approach permitted faster extraction times and higher enrichment factors for analytes with low vapor pressure whereas the HS-SDME approach exhibited better extraction efficiencies for analytes with relatively higher vapor pressure.

Using an Optical Probe as the Microdrop Holder in Headspace Single Drop Microextraction: Determination of Sulfite in Food Samples

A novel headspace single-drop microextraction method (HS-SDME) for determination of sulfite in the form of sulfur dioxide was developed. An optical probe was used as the droplet holder in the HS-SDME procedure, and the analytical signal (absorbance) was monitored online during the extraction process. The method is based on the conversion of sulfite to volatile sulfur dioxide by acidification of the analyzed solution. The liberated SO2 was absorbed by 25 μL of an aqueous mixed reagent solution placed on the optical probe tip and containing Fe(III), 1,10-phenantroline, and an acetic buffer solution of pH 5.6. During the extraction process, Fe(III) reduces to Fe(II) and the Fe(II) formed then reacts with 1,10-phenantroline to form a colored complex. Absorbance was measured at 510 nm. The calibration plot was linear in the range 0.032-0.320 mg L-1 of sulfite (as SO2), with a correlation coefficient of 0.9989. The limit of detection (LOD), calculated as three times the standard deviation of the blank test (n = 10), was found to be 8 μg L-1. The method was applied for analysis of real food samples, such as wine, jam, and juice.

Application of headspace single-drop microextraction (HS-SDME) technique in geochemical exploration for petroleum

Abstract All surface geochemical exploration methods for oil and gas are based on the theory that hydrocarbons generated and trapped at depth seep in varying but detectable quantities to the surface, and the main components detected are usually C1 -C5 hydrocarbons. The C1 -C4 hydrocarbons could come from degradation of organic matter by microbial organisms, while the gasoline range hydrocarbons are totally sourced from thermogenic processes. Therefore, the detection of gasoline range hydrocarbons in soils or sediments could be the most direct evidence for hydrocarbon seepage and the method used to detect the C6 -C12 range hydrocarbons could be a useful technique for surface geochemical exploration method for petroleum. However, because the concentration of gasoline range hydrocarbons in the soils or sediments are usually very low, and the present techniques for detecting those hydrocarbons are not adequate, the gasoline range hydrocarbons have seldom been used in surface geochemical exploration for oil and gas. In this study, the headspace single-drop microextraction (HS-SDME) technique coupled with gas chromatography-flame ionization detection (GC-FID) was employed to determine C6 -C12 gasoline range hydrocarbons in well drilling mud sample. The results show that the C6 -C12 hydrocarbons in the samples could be detected by HS-SDME, and the reservoir depth determined by the concentration of C6 -C12 hydrocarbons was the same with the actual petroleum reservoir depth, which indicated further that the HS-SDME method could be used in geochemical exploration for petroleum.

Ion Chromatography for Rapid and Sensitive Determination of Three Alkylamines in Wastewater after Headspace Single-Drop Microextraction

A novel headspace single drop microextraction method coupled with ion chromatography was developed for the determination of propylamine, sec-butylamine, and butylamine in industrial wastewater. The method was based on a deionized water microdrop (10 µL) which hung in the headspace of the sample bottle. The ammonium ion produced in the microdrop was measured subsequently by ion chromatography. The conditions for the single-drop microextraction process were optimized by employing an orthogonal experimental design. The enrichment factors of propylamine, sec-butylamine, and butylamine were 40, 73, and 45, respectively, under the optimal conditions. Baseline separation of three alkylamines was achieved within 15 min in concentrations varying from 0.5 to 15.0 mg L−1 (, , ) and the detection limits (signal-to-noise ratio of 3) were 0.96, 4.28, and 8.18 µg L−1 by using 30 mmol L−1 methanesulfonic acid as the eluent. The method was successfully employed to determine the three aliphatic amines in industrial wastewater with recoveries of 97.2% to 102.9%. The relative standard deviation, according to peak area, was 0.96%. The experimental results showed that headspace single-drop microextraction combined with ion chromatography is a simple, rapid, and low-cost method for the determination of the alkylamines.

Headspace-single drop microextraction (HS-SDME) in combination with high-performance liquid chromatography (HPLC) to evaluate the content of alkyl- and methoxy-phenolic compounds in biomass smoke

The content of ten phenolic compounds present in four different biomass smoke materials: rock rose (Cistus monpelienisis), prickly pear (Opuntia ficus indica), pine needles (Pinus canariensis), and almonds skin (Prunus dulcis), have been evaluated. The sampling method mainly consisted of a trap alkaline solution to solubilize the phenols, and was optimized by an experimental design. Average sampling efficiencies of 78.1% and an average precision value of 10.6% (as relative standard deviation, RSD), were obtained for the selected group of phenols. The trapped phenolates were further analyzed by a headspace-single drop microextraction (HS-SDME) procedure, in combination with high-performance liquid chromatography (HPLC) with UV detection. The optimum variables for the HS-SDME method were: 1-decanol as extractant solvent, 3.5μL of microdrop volume, 2mL of sample volume, a pH value of 2, saturation of NaCl, an extraction temperature of 60°C, and an extraction time of 25min. The optimized HS-SDME method presented detection limits ranging from 0.35 to 5.8μgmL−1, RSD values ranging from 0.7 to 7.4%, and an average relative recovery (RR) of 99.8% and an average standard deviation of 5.2. The average content of phenolic compounds in the biomass materials studied were 70, 161, 206 and 252mgkg−1 of biomass for prickly pear, almonds skin, rock rose, and pine needles, respectively. The main components of the smokes were vanillin, phenol and methoxyphenols, in all smoking materials studied.

Comparison of HS-SDME with SPME and SPE for the Determination of Eight Organochlorine and Organophosphorus Pesticide Residues in Food Matrices

A headspace single-drop microextraction (HS-SDME) procedure is optimized for the analysis of organochlorine and organophosphorous pesticide residues in food matrices, namely cucumbers and strawberries by gas chromatography with an electron capture detector. The parameters affecting the HS-SDME performance, such as selection of the extraction solvent, solvent drop volume, extraction time, temperature, stirring rate, and ionic strength, were studied and optimized. Extraction was achieved by exposing 1.5 microL toluene drop to the headspace of a 5 mL aqueous solution in a 15-mL vial and stirred at 800 rpm. The analytical parameters, such as linearity, correlation coefficients, precision, limits of detection (LOD), limits of quantification (LOQ), and recovery, were compared with those obtained from headspace solid-phase microextraction (HS-SPME) and solid-phase extraction. The mean recoveries for all three methods were all above 70% and below 104%. HS-SPME was the best method with the lowest LOD and LOQ values. Overall, the proposed HS-SDME method is acceptable in the analysis of pesticide residues in food matrices.

Single-drop microextraction and gas chromatography–mass spectrometry for the determination of volatile aldehydes in fresh cucumbers

Headspace single-drop microextraction (HS-SDME) was used as a rapid and reliable method for the isolation and preconcentration of volatile aldehydes from fresh cucumbers. The utility of this methodology is demonstrated in the determination of (E)-2-nonenal and (E,Z)-2,6-nonadienal. The limit of detection, linearity and repeatability have been determined for 2,6-nonadienal and (E)-2-nonenal. Limits of detection for nonenal and nonadienal were 0.05 and 0.04 mg kg(-1), respectively. The repeatability of extraction was obtained with the RSD values lower than 13%. Concentrations of target aldehydes in fresh cucumbers obtained by means of the HS-SDME method were in the range 9.4-12.5 (nonadienal) and 2.6-3.8 mg kg(-1) (nonenal). The results of the single-drop extraction in combination with gas chromatography show promising potential for the analysis of volatile aldehydes in vegetables.

Headspace extraction of alcohols into a single drop

The possibility of applying headspace microextraction into a single drop for the determination of alcohols in aqueous solutions is demonstrated. A drop of ethylene glycol containing butan-2-one as an internal standard is used for extraction. The analytes are extracted by suspending a 1 μl extracting drop directly from the tip of a microsyringe fixed above an extraction vial with a septum such that the needle passes through the septum and the needle tip appears above the surface of the solution. After the extraction is finished the drop is retracted back into the needle and injected directly into a GC column. Optimization of experimental conditions (sampling time, sampling temperature, stirring rate and ionic strength of the solution) with respect to the extraction efficiency were investigated and the linear range and the precision were examined. This headspace single drop microextraction method was applied to the analysis of beer.