Type Of Extraction Solvent Research Articles

Enrichment of Copper as 1-(2-Pyridylazo)-2-Naphthol Complex by the Combination of Dispersive Liquid–Liquid Microextraction/Flame Atomic Absorption Spectrometry

A rapid, simple, selective, economical, and sensitive dispersive liquid-liquid microextraction methodology has been established for the preconcentration of copper (Cu) at trace levels. The Cu(II) was complexed with 1-(2-pyridylazo)-2-naphthol; ethanol and carbon tetrachloride were used as disperser and extraction solvents, respectively. To obtain quantitative recovery of Cu(II), the effects of parameters influencing its extraction efficiency and subsequent determinations, i.e., pH, amount of complexing reagent, extraction time, and type and volume of disperser and extraction solvents, were examined. LOD and LOQ were 0.06 and 0.20 microg/L, respectively. The enrichment factor of the proposed method was 60, and the RSD <5%. TMDA 51.3 and TMDA 70 fortified water certified reference materials were analyzed for validation of the procedure. The developed microextraction procedure has been used for the preconcentration of Cu(II) in water samples with acceptable results.

Ultrasonic-Assisted Dispersive Liquid Phase Microextration with Low-Volume Toxic Solvent for the Separation of Strontium and its Application for Strontium Isotope Determination

In this paper, a new and novel method of ultrasonic-assisted dispersive liquid phase microextration was applied for the pre-concentration of trace strontium ion in water samples, which was determined by inductively coupled plasma optical emission spectroscopy. In this pretreatment, acetonitrile was used as dispersive solvent, 1,1,2,2-tetrachloroethane as an extractant and dicyclohexyl-18-crown-6 as the chelating reagent. The factors influencing the extraction of the method were optimized. These factors were type and volume of extraction solvents, the type and volume of dispersive solvents, pH value and extraction time. The linear ranged from 40 to 2000 mu g/L with the limit of detection of 12 mu g/L. Under the optimum condition, the amount of strontium and the variation of strontium isotopic composition in four real water samples were investigated by the proposed method. The method can be applied to the determination of strontium and its isotopic composition in environmental samples.

Development and validation of a rapid and sensitive gas chromatographic method for the analysis of some phenolic compounds in vegetable oils

A new method based on simultaneous derivatization and air-assisted liquid–liquid microextraction (AALLME) is developed for the determination of some phenolic compounds in different oils. In this method, the analytes are extracted from the oil samples by NaOH solution, then a few μL of butyl chloroformate and carbon tetrachloride are injected into the NaOH solution containing the extracted analytes, and the resulting mixture is sucked into a syringe and injected several times into a test tube with a conical base. After centrifugation of the resulting cloudy solution, the fine droplets of the organic phase containing the derivatized phenols are precipitated at the bottom of the tube. Then, 1 μL of the settled phase is injected into a gas chromatograph with flame ionization detection (GC-FID). The effects of extraction solvent type, derivatization agent and extraction solvent volumes, number of extractions and reaction time on the extraction efficiency were investigated. Under the optimum conditions, the enrichment factors (EF), extraction recoveries (ER), and enhancement factors (EnF) were high and ranged between 572–991, 60–109%, and 497–1471, respectively. The calibration graphs were linear in the concentration range of 3–10 000 μg L−1. Relative standard deviations (RSD, %) for the extraction of each of the selected phenols were in the ranges of 2–4% for intra-day (n = 6) and 3–5% (n = 5) for inter-day precision for a concentration of 200 μg L−1 of each analyte. Limits of detection (LOD) were in the range of 1–2 μg L−1. Various oil samples, including olive oil, virgin olive oil, sunflower oil, and colza oil, were successfully analyzed by the proposed method.

Antioxidant capacity of extracts from amaranth (Amaranthus hypochondriacus L.) seeds or leaves

The effect of extraction method and solvent type on antioxidant capacity and total phenolic content of extracts from amaranth (Amaranthus hypochondriacus L.) seeds or leaves were evaluated. Antioxidant compounds were extracted by two methods: magnetic stirring or Soxhlet. For these two methods, methanol, ethanol, or hexane, were tested as solvents. Antioxidant capacity was determined by inhibition of DPPH· radical. Total phenolics were determined by the phenol Folin–Ciocalteu assay. There was a significant effect (p≤0.05) of extraction method and solvent type on antioxidant capacity and total phenolics of studied extracts. Greatest antioxidant capacities, up to 1070equiv. of Trolox (mg/100g dry weight), and total phenolics, up to 619equiv. of gallic acid (mg/100g dry weight), were determined in extracts from the Soxhlet extraction method; methanol was a better extraction solvent for amaranth seeds while ethanol was for leaves. In general, extracts from amaranth leaves exhibited more antioxidant capacity than those from seeds. Antioxidant capacities of studied extracts are not only due to phenolics.

Microwave-Assisted Extraction/Dispersive Liquid–Liquid Microextraction Coupled with DSI-GC-IT/MS for Analysis of Essential Oil from Three Species of Cardamom

A novel method of microwave-assisted extraction coupled with polyethylene Pasteur-pipette-based dispersive liquid–liquid microextraction applying low-density organic solvent (MAE-LDS-DLLME) was successfully developed for extraction and preconcentration of essential oil from three species of cardamom (Semen Alpiniae Katsumadai, Fructus Amomi Rotundus, and Semen Myristicae). The essential oil was analyzed by gas chromatography-ion trap/mass spectrometry (GC-IT/MS) using a ChromatoProbe direct sample introduction (DSI) device. The effects of various parameters affecting the extraction process, such as the type of extraction solvent and dispersive solvent, ionic strength, microwave power, and irradiation time, were investigated thoroughly and optimized. The optimal conditions were extraction solvent of toluene, dispersive solvent of methanol, microwave power of 80 W, irradiation time of 4.0 min, plant material amount of 0.1 g, and no addition of salt. Compared with hydrodistillation, MAE-DLLME-DSI-GC–MS is a simple, rapid, low-cost, efficient, and environmentally friendly method, and the essential oil contains higher amounts of oxygenated compounds, which play an important and valuable role in terms of their contribution to the fragrance of the essential oil. In this work, we also studied the main components of the three varieties of cardamom. Qualitative and quantitative differences in the components of the three essential oils were found to be present. Based on comparison of the main bioactive compounds of essential oil, a significant difference was found between Semen Alpiniae Katsumadai or Fructus Amomi Rotundus and Semen Myristicae. This study also provides a new approach for quality assessment of traditional Chinese medicines.

Dispersive Liquid–Liquid Microextraction Followed by Capillary High-Performance Liquid Chromatography for the Determination of Six Sulfonylurea Herbicides in Fruit Juices

In this study a simple, rapid, and efficient method has been developed for the determination of six sulfonylurea herbicides (SUHs): triasulfuron, metsulfuron-methyl, chlorsulfuron, flazasulfuron, chlorimuron-ethyl, and primisulfuron-methyl in commercial grape and apple juice samples, using dispersive liquid–liquid microextraction coupled with capillary high-performance liquid chromatography with diode array detection. Various parameters that influence the extraction efficiency, such as the type and volume of extraction and disperser solvents, sample pH, and salt addition, were investigated and optimized. Under the optimum conditions, limits of detection and quantification of the method were in the ranges of 2–9 and 8–29 μg L−1, respectively, lower than the maximum residue limits set by the European Union for the raw fruits, such as grape and apple. The intra- and inter-day relative standard deviations varied from 1.0 to 8.2 and 1.8 to 9.8 %, respectively, with recoveries between 72.0 and 109.5 % for commercial grape (both white and red) and apple juice samples, showing satisfactory accuracy for the determination of SUHs in fruit juices.

Coupling of solvent-based de-emulsification dispersive liquid–liquid microextraction with high performance liquid chromatography for simultaneous simple and rapid trace monitoring of 2,4-dichlorophenoxyacetic acid and 2-methyl-4-chlorophenoxyacetic acid

A simple, rapid, and efficient sample pretreatment technique, based on solvent-based de-emulsification dispersive liquid-liquid microextraction (SD-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for simultaneous preconcentration and trace detection of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) in water and urine samples. Some parameters such as acidity of solution, the amount of salt, type, and volume of extraction solvents, type of disperser/de-emulsifier solvent, and its volume were investigated and optimized. Under optimum extraction conditions, the limits of detections (LODs) of this method for MCPA and 2,4-D were 0.2 and 0.6 μg L(-1) (based on 3S(b)/m) in water and 0.4 and 1.6 μg L(-1) in urine, respectively. Furthermore, dynamic linear range of this method for MCPA and 2,4-D was 1-300 and 2-400 μg L(-1), repectively. Finally, the applicability of the proposed method was evaluated by extraction and determination of the herbicides in urine and different water samples.

Determination of Parabens in Beverage Samples by Dispersive Liquid–Liquid Microextraction Based on Solidification of Floating Organic Droplet

A simple and efficient method for dispersive liquid-liquid microextraction of methylparaben, ethylparaben, propylparaben and butylparaben in real beverage samples was developed. It is making use of solidified floating organic droplets of 1-dodecanol which has low density and a proper melting point. Parameters influencing the extraction efficiency, such as the type of extraction and dispersive solvent, the volume of extraction and dispersive solvent, salt effect, pH, extraction time, were optimized and resulted in enrichment factors (EFs) of 84 for methylparaben, 103 for ethylparaben, 115 for propylparaben and 126 for butylparaben. The limits of detection for parabens were 1.52, 1.06, 0.32 and 0.17 ng/mL, respectively. Excellent linearity with coefficients of correlation from 0.9970 to 0.9997 was observed in the concentration range of 5-1,000 ng/mL. The repeatability of the proposed method expressed as relative standard deviations (RSDs) ranged from 2.54 to 3.89% (n = 5). The relative recoveries for parabens in beverage samples were good and in the ranges of 89.8-109.9, 90.2-107.3, 90.9-101.7 and 92.3-118.1%, respectively. Thus, the proposed method has excellent potential for the determination of parabens in beverage samples.

Preconcentration of organochlorine pesticides in aqueous samples by dispersive liquid-liquid microextraction based on solidification of floating organic drop after SPE with multiwalled carbon nanotubes

SPE joined with dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) as a novel technique combined with GC with electron-capture detection has been developed as a preconcentration technique for the determination of organochlorine pesticides (OCPs) in water samples. Aqueous samples were loaded onto multiwalled carbon nanotubes as sorbent. After the elution of the desired compounds from the sorbent by using acetone, the DLLME-SFO technique was performed on the obtained solution. Variables affecting the performance of both steps such as sample solution flow rate, breakthrough volume, type and volume of the elution, type and volume of extraction solvent and salt addition were studied and optimized. The new method provided an ultra enrichment factor (8280-28221) for nine OCPs. The calibration curves were linear in the range of 0.5-1000 ng/L, and the LODs ranged from 0.1-0.39 ng/L. The RSD, for 0.01 μg/L of OCPs, was in the range of 1.39-13.50% (n = 7). The recoveries of method in water samples were 70-113%.

Novel multiple-solvent simultaneous microextraction for flavonoid and anthraquinone preconcentration in traditional Chinese medicine

In this study, a novel multiple-solvent simultaneous microextraction (MSSME) method is presented and introduced to preconcentrate flavonoids and anthraquinones from traditional Chinese medicines simultaneously. This technique was performed in one step by using two different solvents (immiscible with each other) carried by two filter membranes (1 cm × 1 cm), which were used as extraction devices. High-performance liquid chromatography with ultraviolet detection (HPLC/UV) was subsequently conducted. The wide exchange surface and multiple solvents respective extraction provided by the filter membrane showed that the proposed technique could be potentially applied as a sample pretreatment technology. The variables influencing MSSME, such as types of extraction solvents, filter membrane area (or volumes of extraction solvents), aqueous phase pH, ionic strength, extraction stirring rate, extraction time, and sample volume were investigated and optimized. Under optimized conditions, the enrichment factors of the analytes were 68 to 132 and the limits of detection were <0.96 ng mL−1. In addition, satisfactory recoveries of 80.1% to 119.2% and precisions of 2.2% to 8.8% were achieved. These results show that MSSME coupled with HPLC/UV is a simple, rapid, practical, and effective method to extract and preconcentrate different types of trace components from complex samples simultaneously.

Ultrasound-assisted dispersive liquid–liquid microextraction combined with high performance liquid chromatography for sensitive determination of five biogenic amines in fermented fish samples

Ultrasound-assisted dispersive liquid–liquid microextraction (USADLLME) coupled to high performance liquid chromatography with fluorescence detection was developed for the simultaneous determination of five biogenic amines (histamine, tryptamine, cadaverine, tyramine and spermidine). The biogenic amines were derivatized with 9-fluorenylmethyl chloroformate before analysis. The five biogenic compounds were separated within 30 min using a C18 column and gradient elution with acetonitrile and 1% acetic acid. The parameters affecting extraction efficiency by USADLLME such as type and volume of extraction solvent and disperser were studied. Under the optimum conditions for USADLLME, 200 μL of 1-octanol as extraction solvent, 200 μL acetonitrile as disperser with the aid of ultrasonication for 1 min, resulted in enrichment factors in the range of 12–42. Good linearity was obtained from 0.2–300 ng mL−1 (r2 > 0.992). Limits of detection ranged from 0.02 to 0.5 ng mL−1. The proposed method was applied in the analysis of biogenic amines in fermented fish samples, good recoveries were obtained in the range of 77.02–126.38%.

Application of ultrasound-assisted emulsification microextraction for simultaneous determination of aminophenol isomers in human urine, hair dye, and water samples using high-performance liquid chromatography

Aminophenol isomers (2-, 3-, and 4-aminophenols) are typically classified as industrial pollutants with genotoxic and mutagenic effects due to their easy penetration through the skin and membranes of human, animals, and plants. In the present study, a simple and efficient ultrasound-assisted emulsification microextraction procedure coupled with high-performance liquid chromatography with ultraviolet detector was developed for preconcentration and determination of these compounds in human fluid and environmental water samples. Effective parameters (such as type and volume of extraction solvent, pH and ionic strength of sample, and ultrasonication and centrifuging time) were investigated and optimized. Under optimum conditions (including sample volume: 5mL; extraction solvent: chloroform, 80µL; pH: 6.5; without salt addition; ultrasonication: 3.5min; and centrifuging time: 3min, 5000rpmmin(-1)), the enrichment factors and limits of detection were ranged from 42 to 51 and 0.028 to 0.112µgmL(-1), respectively. Once optimized, analytical performance of the method was studied in terms of linearity (0.085-157µgmL(-1), r (2)>0.998), accuracy (recovery=88.6- 101.7%), and precision (repeatability: intraday precision<3.98%, and interday precision<5.12%). Finally, applicability of the method was evaluated by the extraction and determination of these compounds in human urine, hair dye, and real water samples.

Recent developments in dispersive liquid–liquid microextraction

During the past 7 years and since the introduction of dispersive liquid-liquid microextraction (DLLME), the method has gained widespread acceptance as a simple, fast, and miniaturized sample preparation technique. Owing to its simplicity of operation, rapidity, low cost, high recovery, and low consumption of organic solvents and reagents, it has been applied for determination of a vast variety of organic and inorganic compounds in different matrices. This review summarizes the DLLME principles, historical developments, and various modes of the technique, recent trends, and selected applications. The main focus is on recent technological advances and important applications of DLLME. In this review, six important aspects in the development of DLLME are discussed: (1) the type of extraction solvent, (2) the type of disperser solvent, (3) combination of DLLME with other extraction methods, (4) automation of DLLME, (5) derivatization reactions in DLLME, and (6) the application of DLLME for metal analysis. Literature published from 2010 to April 2013 is covered.

Temperature-controlled ultrasound- and vortex-assisted liquid-liquid microextraction combined with GC for the determination of the concentrations of organophosphorus pesticides in beverage samples

The aim of this work was to develop temperature-controlled ultrasound- and vortex-assisted liquid-liquid microextraction as a fast and efficient approach for the extraction of nine organophosphorus pesticides in beverage samples followed by GC with flame photometric detection analysis. The combination of ultrasonication and vortexing were used to assist the microextraction, and the use of a dispersion solvent was avoided. Several variables that could potentially affect the extraction efficiency, namely, the type and volume of extraction solvent, sequence, and time of ultrasonication and vortexing, ultrasonication bath temperature and ionic strength were optimized. Under optimum conditions, the calibration graphs were linear over the range of 0.5-200 μg/L. The LOD (S/N = 3) was between 0.01 and 0.05. The optimized method exhibited a good precision level with RSD values between 4.5 and 9.8%. The enrichment factors for the nine organophosphorus pesticides were between 224 and 339. Four beverage samples were successfully analyzed using the proposed method.

Reduced pressure extraction of oleuropein from olive leaves (Olea europaea L.) with ultrasound assistance

In this study, oleuropein was extracted from Frantoio olive leaves with ultrasound-assisted and reduced-pressure extraction (URPE). Then, it was characterized using HPLC-UV–vis detection. The effects of several important factors, i.e., the type and concentration of extraction solvent, extraction time, extraction temperature, ultrasonic power, liquid to solid ratio and the extraction pressure on the extraction yield of oleuropein from olive leaves, were investigated. The optimal conditions were obtained as follows: ethanol concentration 75% (v/v), extraction temperature 50°C, ultrasonic power 600W, extraction time 3min, liquid to solid ratio 30:1 (ml/g), and extraction pressure 25kPa. Under these optimal conditions, the oleuropein extraction was 7.08±0.05%. A total yield of oleuropein of 7.67±0.02% was obtained after three extractions using URPE. The extraction efficiency reached 92.3% after one extraction. Additionally, compared with the other extraction techniques, i.e., conventional solvent extraction (CSE) under atmospheric pressure, reduced-pressure boiling extraction (RBE), and ultrasound-assisted extraction (UAE), the oleuropein yield and extraction time by URPE was the highest and shortest, respectively. In addition, scanning electron microscope (SEM) imaging of olive leaves after the extraction was performed. URPE could break the olive leaf cell effectively. The results indicated that URPE was an extremely useful and important extraction method for natural products.

Measurement of the oxidative potential of PM2.5 and its constituents: The effect of extraction solvent and filter type

The capacity of Particulate Matter (PM) to oxidise target molecules, defined as its oxidative potential (OP), has been proposed as a biologically more relevant metric than PM mass. Different assays exist for measuring OP and their methodologies vary in the choice of extraction solvent and filter type. Little is known about the impact of extraction and filter type on reported OP. Four a-cellular assays; electron spin resonance (ESR), dithiothreitol (DTT), ascorbate acid depletion (AA) and reductive acridinium triggering (CRAT) assay were chosen to evaluate whether these differences affect the OP measurement, the correlation between OP from different assays and the association with PM chemical composition. We analysed 15 urban 48–72 h PM2.5 samples collected on quartz and Teflon filters. The choice of extraction solvent had only a significant effect on OPDTT, while all OP measures for quartz filters were heavily attenuated. OP values derived from quartz were, however, highly correlated with those derived from Teflon. OPDTT correlated highly with OPCRAT, and OPESR correlated highly with OPAA. These correlations were affected by the choice of filter type. Correlations between OP and PM chemical composition were not affected by filter type and extraction solvent. These findings indicate that the measurement of relative OP reactivity is not greatly influenced by filter type and extraction solvent for the investigated assays. This robustness is also promising for exploratory use in monitoring and subsequent epidemiological studies.

Simultaneous derivatization and ultrasound-assisted dispersive liquid–liquid microextraction of chloropropanols in soy milk and other aqueous matrices combined with gas-chromatography–mass spectrometry

A novel approach involving ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) and derivatization combined with gas chromatography–mass spectrometry was developed for the determination of chloropropanols in water and beverages. UA-DLLME was optimized as less solvent-consuming and cost-effective extraction method for water, fruit juice, milk and soy milk samples. The effect of parameters such as the type and volume of extraction solvent, the type and volume of dispersive solvent, amount of derivatization agent, temperature, pH of sample and ionic strength was investigated and optimized for each specimen, using experimental designs. By adding acetonitrile as dispersive solvent, N-heptafluorobutyrylimizadole (HFBI) as derivatization agent and chloroform as extraction solvent, the extraction-derivatization and preconcentration were simultaneously performed. The analytical concentration range was investigated in detail for each analyte in the different samples, obtaining linearity with R2 ranging between 0.9990 and 0.9999. The method detection limits were in the range of 0.2–1.8μgL−1 (water), 0.5–15μgL−1 (fruit juices) and 0.9–3.6μgkg−1 (milk) and 0.1–1.0μgkg−1 (soy milk). The method was applied to the analysis of a variety of specimens, with recoveries of 98–101% from water, 97–102% from juices, 99–103% from milk and 97–105% from soy beverage. The relative standard deviation (precision, n=6) varied between 1.3 and 4.9%RSD in water, 2.3 and 5.8%RSD in juices, 1.0 and 5.7%RSD in milk and 3.9 and 9.3%RSD in soy milk. The proposed method was applied to analysis of twenty-eight samples. 1,3-Dichloro-2-propanol was found in an influent water sample from urban wastewater treatment plant (WWTP) (2.1±0.04mgL−1) but no chloropropanols were found in the corresponding effluent water sample. This result suggests that the purification system used in the WWTP has been effective for this compound. Moreover, the results revealed the presence of 3-chloropropane-1,2-diol (3-MCPD) and 2,3-dicloro-2-propanol (2,3-DCP) in soy milk at concentrations within the ranges 19.2–95.0μgkg−1 and 3.0–14.3μgkg−1, respectively. The method is suitable for the determination of target contaminants in liquid samples, particularly for environmental and safety food control fields.

Determination of lignans in Wuweizi by using magnetic bar microextraction and HPLC

In this paper, a magnetic bar microextraction was developed to extract schisandrin A, schisantherin A, and deoxyschizandrin from Wuweizi. The analytes were determined by HPLC. A stainless-steel wire was inserted into the hollow of the hollow fiber to make the magnetic bar. The bar can be used to stir the extraction system and extract the analytes, and was isolated from the extract system by magnetic force. Several experimental parameters, including type and volume of extraction solvent, the number of magnetic bars, extraction temperature and time, stirring speed and NaCl concentration were investigated and optimized. The LODs for schisandrin A, schisantherin A, and deoxyschizandrin were 0.14, 0.06, and 0.10 g/mL, respectively. The recoveries were in the range of 70.90-106.67% and the RSDs were < 8.84%. Compared with ultrasound-assisted and Soxhlet extraction, when the present method was applied, the extraction time was shorter, the sample amount was smaller, and the consumption of organic solvent was lower.

Liquid–Liquid Microextraction of Nitrophenols Using Supramolecular Solvent and Their Determination by HPLC with UV Detection

A novel, efficient, and environmentally friendly method—supramolecular solvent liquid–liquid microextraction (SMS-LLME) combined with high-performance liquid chromatography (HPLC)—was first established for the determination of p-nitrophenol and o-nitrophenol in water samples. Several important parameters influencing extraction efficiency, such as the type and volume of extraction solvent, pH of sample, temperature, salt effect, extraction time, and stirring rate, were optimized in detail. Under the optimal conditions, the enrichment factor was 166 for p-nitrophenol and 160 for o-nitrophenol, and the limits of detection by HPLC were 0.26 and 0.58 μg L−1, respectively. Excellent linearity with coefficients of correlation from 0.9996 to 0.9997 was observed in the concentration range of 2–1,000 μg L−1. The ranges of intra- and interday precision (n = 5) at 100 μg L−1 of nitrophenols were 5.85–7.76 and 10.2–11.9 %, respectively. The SMS-LLME method was successfully applied for preconcentration of nitrophenols in environmental water samples.

Determination of twelve herbicides in tobacco by a combination of solid–liquid–solid dispersive extraction using multi-walled carbon nanotubes, dispersive liquid-liquid micro-extraction, and detection by GC with triple quadrupole mass spectrometry

We report on a method for the determination of twelve herbicides using solid–liquid–solid dispersive extraction (SLSDE), followed by dispersive liquid-liquid micro-extraction (DLLME) and quantitation by gas chromatography with triple quadrupole mass spectrometric detection. SLSDE was applied to the extraction of herbicides from tobacco samples using multi-walled carbon nanotubes (MWCNTs) as clean-up adsorbents. The effect of the quantity of MWCNTs on SLSDE, and of type and volume of extraction and disperser solvents and of salt effect on DLLME were optimized. Good linearity is obtained in the 5.0 - 500 μg kg−1 concentration range, with regression coefficients of >0.99. Intra-day and inter-day repeatability, expressed as relative standard deviations, are between 3 and 9 %. The recoveries in case of herbicide-spiked tobacco at concentration levels of 20.0, 50.0 and 100.0 g kg−1 ranged from 79 to 105 %, and LODs are between 1.5 and 6.1 μg kg−1. All the tobacco samples were found to contain butralin and pendimethalin at levels ranging from 15.8 to 500.0 μg kg−1.