Microwave Extraction Time Research Articles

Optimization of Combined Microwave and Ultrasound Extractions of Cannabinoids Compounds from Cannabis indica L. (Blueberry Cultivar) Using Response Surface Methodology

Microwave and ultrasound are novel technologies that are widely used for extracting bioactive compounds from plant materials. In this study, combined extraction techniques, microwave and ultrasound, were applied to extract cannabinoids, cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC), from Cannabis indica L. (Blueberry cultivar). Three independent variables including solid to liquid ratio (X1, A: 1:10-1:30 w/v), microwave extraction time (X2, B: 5-20 min), and ultrasound extraction time (X3, C: 10-30 min) were optimized using central composite design (CCD). The experimental data obtained was fitted to a second-order polynomial equation using multiple regression analysis and additionally analyzed using appropriate statistical methods (analysis of variance, ANOVA). The optimum conditions were determined according to the solid to liquid ratio (X1, A) of 1:22 (w/v), microwave extraction time (X2, B) of 5 min and ultrasound extraction time (X3, C) of 14 min. Under these conditions, the experimental CBD and THC content was 0.298±0.001 mg/g dry weight and 91.35±0.35 mg/g dry weight, respectively. The experimentally-achieved values were in accordance with those estimated by the CCD model, suggesting the applicability of the utilized model and the favorable result of CCD’s application in the optimization of the combined microwave and ultrasound extraction.

An Ultra-Fast and Green LC-MS Method for Quantitative Analysis of Aesculin and Aesculetin in Cortex Fraxini

This study aims to develop a fast and eco-friendly liquid chromatography–mass spectrometry (LC-MS) method for the determination of aesculin and aesculetin in Cortex Fraxini. Ultrapure water was used as the solvent during the microwave-assisted extraction process to prepare the Cortex Fraxini sample. This extraction method reduces the cost of the harmful solvent (only ultrapure water was used) and microwave extraction time (1 min). The LC separation was conducted using an Agilent InfinityLab Poroshell 120 EC-C18 column (2.1 mm × 30 mm, 2.7 µm) with a mobile phase consisting of 0.1% formic acid and acetonitrile (90:10, v/v) at a flow rate of 0.6 mL/min. Isocratic elution was employed, and the analytes were detected by MS. Through careful optimization and selection of LC-MS conditions, the analysis time was reduced to 1 min, demonstrating the method’s efficiency. The developed method was validated and exhibited excellent specificity, linearity, limit, precision, accuracy, and stability in quantifying aesculin and aesculetin in the Cortex Fraxini samples. The analysis result revealed the presence of aesculin (ranging from 3.55 to 18.8 mg/g) and aesculetin (ranging from 1.01 to 16.2 mg/g) in all ten batches of Cortex Fraxini samples. Compared to the reported LC methods, this approach substantially reduces the total analysis time and requires a minuscule volume of organic solvents. An “Analytical Eco-Scale” assessment was used to evaluate the different assay methods of Cortex Fraxini. The current LC-MS method scored an impressive 90; it was better than the other four reports’ LC methods. Thus, the developed LC-MS method is rapid and green, which is helpful for the quality evaluation of Cortex Fraxini.

Extraction process optimization of essential oil from Mellissa officinalis L. using a new ultrasound-microwave hybrid-assisted Clevenger hydrodistillation

The limited efficiency of traditional hydrodistillation extraction methods has hindered the development of essential oils (EOs). This study introduces an innovative method for enhancing the production of EOs from Mellissa officinalis L. The method involves ultrasonic and microwave-coupled Clevenger hydrodistillation, which utilizes a proprietary distillation device (PDD) extraction process. Yield optimisation was determined systematically by response surface methodology following single-factor experiments. The maximum extraction yield (0.21 ± 0.0019%) was achieved when the liquid-to-solid ratio, microwave extraction power, and microwave extraction time were set to 9.74 mL/g, 559.60 W, and 75 mins, respectively. The new process produced 74.79% and 73.55% more EOs than the electric furnace heating-assisted PDD and the microwave-assisted traditional Clevenger hydrodistillation. The combination of microwave and a modified PDD showed better results for EOs extraction, and it has great potential to improve the production efficiency of M. officinalis EOs.

Biosynthesis of silver nanoparticles using extract of banana peel waste assisted by microwave irradiation

Silver (Ag) nanoparticles are among the most desirable nanomaterials for a variety of applications, such as lithium-ion battery, water pollution monitoring, photocatalytic water splitting, and medical devices. Their increased production and integration in environmental applications play an important role for nanoscience and nanotechnology in engineering. The synthesis methods of Ag nanoparticles include physical, chemical, and biological routes. In this study, we reported a rapid, eco-friendly, and cost-efficient method to synthesize Ag nanoparticles using an extract of banana peel waste as a reducing and capping agent under microwave radiation. A comparison between the conventional heating method and microwave radiation revealed that the microwave radiation method for the extraction of banana peel waste and the synthesis of Ag nanoparticles required much shorter extraction and reaction times. The effects of extraction conditions (banana peel content and extraction time) and synthesis conditions (silver nitrate concentration and reaction time) on Ag nanoparticles were investigated. The optimum conditions were found to be for the extraction: 50 g/L banana peel-to-water ratio and microwave extraction time of 140 s at 800 W and for the Ag nanoparticles synthesis: microwave reaction time of 120 s at 800 W and 1 mM silver nitrate solution and. Plasmonic Ag nanoparticles with a surface plasmon resonance peak at 420 nm and an average size of about 149 nm were synthesized.

Multi-step reflux extraction of bio-pharmaceutical phenolic bioactives from balsam apple (Momordica balsamina L.)

In this study, the impacts of parameter combinations on the response (total phenolic yield) were evaluated using the single experiments and two-level factorial design. The investigated parameters with their value range include; the microwave extraction time (1–5 min), power level (400–600 W), temperature (60–80°C), the solvent-feed ratio, SFR (8–12 mL/g) and solvent concentration (50–80%). The result of this investigation succinctly presented the solvent concentration as the highest contributing parameters, far above the Bonferroni limit (8.37517) and t-value limit (3.18245). However, the temperature, SFR and microwave duration provided insignificant contribution to the response settings. The result of the spectrometry chromatographic analysis identified 22 phenolics compounds from the extracts which invariably revealed their potential biological functions. The study therefore adequately elucidated the contributing factor in the microwave recovery of total phenolic constituents from the M. balsamina leaves with potential use as scale-up parameters in drug applications.

Extraction Optimization and Effects of Extraction Methods on the Chemical Structures and Antioxidant Activities of Polysaccharides from Snow Chrysanthemum (Coreopsis Tinctoria).

In order to explore snow chrysanthemum polysaccharides (SCPs) as functional food ingredients and natural antioxidants for industrial applications, both microwave-assisted extraction (MAE) and ultrasonic-assisted extraction (UAE) were firstly optimized for the extraction of SCPs. Furthermore, the effects of conventional hot water extraction, UAE, and MAE on the chemical structures and antioxidant activities of SCPs were investigated. The maximum extraction yields of SCPs extracted by UAE (4.13 ± 0.24%) and MAE (4.26 ± 0.21%) were achieved at the optimized extraction parameters as follows: ultrasound amplitude (68%) and microwave power (500 W), ultrasound extraction time (21 min) and microwave extraction time (6.5 min), and ratio of liquid to raw material (42.0 mL/g for UAE and 59.0 mL/g for MAE). In addition, different extraction methods significantly affected the contents of uronic acids, the molecular weights, the molar ratio of constituent monosaccharides, and the degree of esterification of SCPs. SCPs exhibited remarkable DPPH (IC50 ≤ 1.702 mg/mL), ABTS (IC50 ≤ 1.121 mg/mL), and nitric oxide (IC50 ≤ 0.277 mg/mL) radical scavenging activities, as well as reducing power (≥ 80.17 ± 4.8 μg Trolox/mg), which suggested that SCPs might be one of the major contributors toward the antioxidant activities of snow chrysanthemum tea. The high antioxidant activities (DPPH, IC50 = 0.693 mg/mL; ABTS, IC50 = 0.299 mg/mL; nitric oxide, IC50 = 0.105 mg/mL; and reducing power, 127.79 ± 2.57 μg Trolox/mg) observed in SCP-M extracted by the MAE method might be partially attributed to its low molecular weight and high content of unmethylated galacturonic acids. Results suggested that the MAE method could be an efficient technique for the extraction of SCPs with high antioxidant activity, and SCPs could be further explored as natural antioxidants for industrial application.

Effect of long term cold storage and microwave extraction time on the physical and chemical properties of citrus pectin

Pectin, acid-extracted by microwave heating under pressure from orange and lime albedo, was cold (−20 °C) stored for 14 years and the physical and chemical properties were compared to the properties of the original microwave-extracted pectin prior to cold storage. The pectin physical and chemical properties were measured by using multi-detector high performance size exclusion chromatography (HPSEC), atomic force microscopy (AFM), amino acid, monosaccharide and degree of esterification compositional analysis following cold storage. The weight average molar mass (Mw), intrinsic viscosity (ηw) and radius of gyration (Rgz) changed following cold storage depending on the time of microwave extraction, but all three parameters decreased with extraction time for both orange and lime pectin, regardless of whether they were analyzed before or after cold storage. All pectin samples had little or no appreciable difference in galacturonic acid content following cold storage, yet the degree of esterification decreased by approximately 50% and total sugar content increased following cold storage for both orange and lime pectin. Homogalacturonan (HG) was the major cold-stored pectin component with lower amounts of rhamnogalacturonan I (RG I) containing arabinogalactan side chains present in pectins extracted for shorter times. Amino acid analysis indicated that protein associated with pectin was enriched in aspartic acid/asparagine, glutamic acid/asparagine, leucine and lysine with UV absorbing phenylalanine and tyrosine also present in cold-stored pectin. UV detection in HPSEC chromatograms for both orange and lime pectins following cold storage, revealed that more protein was associated with higher molar mass pectin at 2.5 min of extraction time. By 10 min of extraction time, there was a larger breakdown of high molar mass pectin and protein shifted to a lower molar mass distribution weight fraction. AFM images showed that small spherical molecules, segmented rods and kinked rods were present in both orange and lime pectin following cold storage.

Sequential Combination of Microwave- and Ultrasound-Assisted Extraction of Total Flavonoids from Osmanthus fragrans Lour. Flowers.

Microwave-assisted and ultrasound-assisted extraction assays were used to isolate total flavonoids (TF) from Osmanthus fragrans flowers. The effects of the solid-liquid ratio, ethanol concentration, microwave power, microwave extraction time, ultrasonic power and ultrasonic extraction time on the yield of TF were studied. A sequential combination of microwave- and ultrasound-assisted extraction (SC-MUAE) methods was developed, which was subsequently optimized by Box-Behnken design-response surface methodology (BBD-RSM). The interaction effects of the ethanol concentration (40–60%), microwave extraction time (5–7 min), ultrasonic extraction time (8–12 min) and ultrasonic power (210–430 W) on the yield of TF were investigated. The optimum operating parameters for the extraction of TF were determined to be as follows: ethanol concentration (48.15%), microwave extraction time (6.43 min), ultrasonic extraction time (10.09 min) and ultrasonic power (370.9 W). Under these conditions, the extraction yield of TF was 7.86 mg/g.

Composition Comparison of Essential Oils Extracted by Hydrodistillation and Microwave-assisted Hydrodistillation from Petroselinum crispum Grown in China

The components of essential oils extracted from Petroselinum crispum seeds were determined by the traditional technique hydrodistillation (HD) and microwave-assisted hydrodistillation (MHD). The optimum conditions of MHD were microwave radiation time 4 min at 600 w, microwave extraction time 40 min at 200 w, and a 1:30 material-water ratio. The yields of HD and MHD essential oils from parsley seeds were 3.44% and 4.45% (v/w), respectively. Thirty-one components were identified in the HD oil, comprising 98.95% of total oil. While thirty-five components were identified in the MHD oil, which accounted for 99.52% of all oil. Myristicin was the main component in both oils. The analysis of the extracts was performed by GC-MS.

Determination of Phthalate Esters in Plastic Track Surface Layer Material by Gas Chromatography

A method was proposed to simultaneously and rapidly determine the content of five kinds of phthalate esters (DMP, DBP, BBP, DnHP, DOP) in plastic track surface layer material by gas chromatography (GC) with the external standard,and the method was first proposed. The sample pretreatment method was microwave-assisted extracted using ethyl acetate as the solvent. Discussed the effects of extraction conditions on the extraction efficiency, microwave extraction time was 30 minutes, microwave extraction temperature was 100°C,the volume of ethyl acetate was 15mL. The results showed that there was a good linear relationship in range of 0.040 to 50 mg/L(R2 was 0.9987-0.9994). The average recoveries of standard addition for five kinds of phthalate esters were between 83.83% and 101.02%, and the relative standard derivations (RSDs (n=6)) ranged from 0.95% to 4.73%. The three times of signal to noise ratio (3 S/N) was used to calculate the detection limit of the method , and the detection limit was 2.5-3.0 mg/kg. The ten times of signal to noise ratio (10 S/N) was used to calculate the quantitation limit of the method, and the limit of quantitation was 8.5-10 mg/kg. This method is simple, effective and suitable for the determination of phthalate esters in plastic track surface layer material.

Effect of Microwave-Assisted Extraction on the Phenolic Compounds and Antioxidant Capacity of Blackthorn Flowers.

This research was undertaken to investigate the influence of extraction parameters during microwave-assisted extraction on total phenolic content, total flavonoids, total hydroxycinnamic acids and total flavonols of blackthorn flowers as well as to evaluate the antioxidant capacity by two different methods (2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity and ferric reducing antioxidant power assays). The investigated extraction parameters were: solvent type and volume fraction of alcohol in solvent (50 and 70% aqueous solutions of ethanol and methanol), extraction time (5, 15 and 25 min) and extraction temperature (40, 50 and 60 °C) controlled by microwave power of 100, 200 and 300 W. Multivariate analysis of variance (MANOVA) was used to evaluate the differences at a 95% confidence level (p≤0.05). The obtained results show that aqueous solution of ethanol was more appropriate solvent for extraction of phenolic compounds (total flavonoids, total hydroxycinnamic acids and total flavonols) than aqueous solution of methanol. The amount of phenolic compounds was higher in 70% aqueous solution of ethanol or methanol, while higher antioxidant capacity was observed in 50% aqueous solution of methanol. Higher temperature of extraction improved the amount of phenolic compounds and also antioxidant capacity determined by 2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity assay. Extensive duration of extraction (15- to 25-minute interval) has a significant effect only on the increase of total phenolic content, while specific phenolic compound content and antioxidant capacity were the highest when microwave extraction time of 5 min was applied.

Microwave-Assisted Solvent Extraction of Melamine from Seafood and Determination by Gas Chromatography–Mass Spectrometry: Optimization by Factorial Design

Melamine attracts considerable attention because of its toxicity. The determination of melamine in seafood was performed by gas-chromatography–mass spectrometry, using an optimized version of a method adopted by the U.S. Food and Drug Administration. The melamine was extracted by closed-vessel microwave-assisted solvent extraction (MAE), as a valid alternative in sample preparation, to reduce analysis time and provide less ambiguous data. The procedure was optimized by means of experimental factorial design considering the three main variables that affect this process: microwave oven power, the maximum temperature inside the extraction tube, and the hold time. The recovery of melamine in spiked samples was used as the elemental response value of the design. Temperature and hold time had a more positive effect on the response than the microwave power. A significant positive interaction was observed between oven power and hold time. A temperature of 70°C and a hold time of 1 min gave a recovery of 92 ± 5% for a microwave power of 600 W. Under these conditions, the total microwave extraction time was approximately 2 minutes, a much shorter time compared to the ultrasonic bath, which required a total time of 40 min. The repeatability of the method was approximately 3%. The limits of quantification were 0.55 mg kg−1 for MAE and 1.9 mg kg−1 for the ultrasonic bath; the linearity was confirmed up to 10 mg kg−1. In conclusion, the MAE procedure was shown to be an excellent alternative to the official method.

Development of an ionic liquid-based microwave-assisted method for simultaneous extraction and distillation for determination of proanthocyanidins and essential oil in Cortex cinnamomi

Cortex cinnamomi is associated with many health benefits and is used in the food and pharmaceutical industries. In this study, an efficient ionic liquid-based microwave-assisted simultaneous extraction and distillation (ILMSED) technique was used to extract cassia oil and proanthocyanidins from Cortex cinnamomi; these were quantified by gas chromatography/mass spectrometry (GC–MS) and the vanillin–HCl colorimetric method, respectively. 0.5M 1-butyl-3-methylimidazolium bromide ionic liquid was selected as solvent. The optimum parameters of dealing with 20.0g sample were 230W microwave irradiation power, 15min microwave extraction time and 10 liquid–solid ratio. The yields of essential oil and proanthocyanidins were 1.24±0.04% and 4.58±0.21% under the optimum conditions. The composition of the essential oil was analysed by GC–MS. Using the ILMSED method, the energy consumption was reduced and the extraction yields were improved. The proposed method was validated using stability, repeatability, and recovery experiments. The results indicated that the developed ILMSED method provided a good alternative for the extraction of both the essential oil and proanthocyanidins from Cortex cinnamomi.

Microwave extraction and rapid isolation of arjunic acid from Terminalia arjuna (Roxb. ex DC.) stem bark and quantification of arjunic acid and arjunolic acid using HPLC‐PDA technique

Arjunic acid and arjunolic acid are main bioactive components of Terminalia arjuna stem bark and reported for various biological activities. In this study, microwave-assisted extraction (MAE) of arjunic and arjunolic acid from stem bark of T. arjuna was investigated with developed and validated HPLC-PDA method, which resulted in the isolation of a novel anticancer molecule i.e. arjunic acid. Effects of several experimental parameters, such as type and volume of extraction solvents, microwave power, microwave extraction time, on the extraction efficiencies of arjunic, and arjunolic acid from stem bark of T. arjuna were evaluated. The optimal extraction conditions identified were 5.0 g quantity of stem bark powder, 20 mL of ethyl acetate, preleaching time 10 min, microwave power 600 W, temperature 65°C, and microwave irradiation time 5 min. The results showed that MAE is a more rapid extraction method with higher yield and lower solvent consumptions than reported methods. The HPLC-PDA analysis method was developed and validated to have good linearity, precision, sensitivity, and accuracy. MAE-HPLC-PDA is a faster, convenient, and appropriate method for isolation and determination of arjunic acid and arjunolic acid in the stem bark of T. arjuna.

Optimization of a Microwave-Coupled Enzymatic Digestion Process to Prepare Peanut Peptides

The best enzyme to prepare peanut peptides, papain, coupled with microwave irradiation was selected from five common proteases according to the results of the yield of peanut peptides [nitrogen solution index (NSI) in trichloroacetic acid (TCA), TCA-NSI] and the degree of hydrolysis (DH). The main factors that influenced the microwave-coupled enzymatic digestion method were optimized by response surface analysis. The optimal conditions obtained were as follows: microwave extraction time, 9.5 min; power, 600 W; substrate concentration, 4%; enzymatic reaction temperature, 50 °C; enzyme quantity, 6,500 U/g; pH, 7.1 (phosphate buffer, 0.05 mol/L). Under these conditions, TCA-NSI was 62.00% and DH was 25.89%, which is higher than that obtained with either protease hydrolysis or microwave hydrolysis alone.

Ionic liquid-based microwave-assisted extraction of essential oil and biphenyl cyclooctene lignans from Schisandra chinensis Baill fruits

Ionic liquid-based microwave-assisted extraction (ILMAE) has been successfully applied in extracting essential oil and four kinds of biphenyl cyclooctene lignans from Schisandra chinensis Baill. 0.25 M 1-lauryl-3-methylimidazolium bromide ionic liquid is selected as solvent. The optimum parameters of dealing with 25.0 g sample are 385 W irradiation power, 40 min microwave extraction time and 1:12 solid-liquid ratio. The yields of essential oil and lignans are 12.12±0.37 ml/kg and 250.2±38.2 mg/kg under the optimum conditions. The composition of the essential oil extracted by hydro-distillation, steam-distillation and ILMAE is analyzed by GC-MS. With ILMAE method, the energy consumption time has not only been shortened to 40 min (hydro-distillation 3.0 h for extracting essential oil and reflux extraction 4.0 h for extracting lignans, respectively), but also the extraction efficiency has been improved (extraction of lignans and distillation of essential oil at the same time) and reduces the environmental pollution. S. chinensis materials treated by different methods are observed by scanning electronic microscopy. Micrographs provide more evidence to prove that ILMAE is a better and faster method. The experimental results also indicate that ILMAE is a simple and efficient technique for sample preparation.

Removal of caffeine from green tea by microwave-enhanced vacuum ice water extraction

In order to selectively remove caffeine from green tea, a microwave-enhanced vacuum ice water extraction (MVIE) method was proposed. The effects of MVIE variables including extraction time, microwave power, and solvent to solid radio on the removal yield of caffeine and the loss of total phenolics (TP) from green tea were investigated. The optimized conditions were as follows: solvent (mL) to solid (g) ratio was 10:1, microwave extraction time was 6min, microwave power was 350W and 2.5h of vacuum ice water extraction. The removal yield of caffeine by MVIE was 87.6%, which was significantly higher than that by hot water extraction, indicating a significant improvement of removal efficiency. Moreover, the loss of TP of green tea in the proposed method was much lower than that in the hot water extraction. After decaffeination by MVIE, the removal yield of TP tea was 36.2%, and the content of TP in green tea was still higher than 170mgg−1. Therefore, the proposed microwave-enhanced vacuum ice water extraction was selective, more efficient for the removal of caffeine. The main phenolic compounds of green tea were also determined, and the results indicated that the contents of several catechins were almost not changed in MVIE. This study suggests that MVIE is a new and good alternative for the removal of caffeine from green tea, with a great potential for industrial application.

Application of magnetic material in the determination of polycyclic aromatic hydrocarbons in tree leaves by high performance liquid chromatography

Carbon coated Fe3O4 magnetic particles (Fe3O4/C) were synthesized by hydrothermal reaction, and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and transmission electron microscopy (TEM). The material is applied to microwave-assisted extraction for clean-up and enrichment of polycyclic aromatic hydrocarbons (PAHs) from tree leaves. Magnetic solid-phase extraction (MSPE) parameters including elution solvents, amount of sorbents and enrichment time are optimized together with microwave extraction time, power, extraction solvents and the ratio of liquid to solid. Under the optimal conditions, the developed method provides spiked recoveries of 77.7–103.8% with RSDs of less than 4.0%, and limits of detection (LOD) of 0.5–2.0 ng g−1. PAHs in tree leaves are successfully determined.

Rapid determination of polyphenols in cut tobacco by microwave-assisted extraction-ultrahigh performance liquid chromatography

A fast microwave-assisted extraction-ultrahigh performance liquid chromatography (MAE-UPLC) method was developed for the simultaneous determination of chlorogenic acid, scopoletin and rutin in cut tobacco. The extraction conditions of polyphenols were determined by single-factor and orthogonal experiment. The optimal conditions were found to be as follows: methanol concentration of 60% (v/v), extraction solvent temperature of 90 °C, microwave extraction time of 1 min and solid to liquid ratio of 1 : 20 (g mL−1), the recovery rates of polyphenols in cut tobacco were between 96.5% and 105.6%, relative standard deviations were lower than 5%. The total analysis time for a sample was less than 20 min, the results were satisfactory.

An accurate and sensitive method for the determination of methylmercury in biological specimens using GC-ICP-MS with solid phase microextraction

A highly sensitive and selective method has been developed for the determination of methylmercury in biological specimens and NIST Standard Reference Materials (SRMs). The procedure involves microwave extraction with acetic acid, followed by derivatization and headspace solid-phase microextraction (SPME) with a polydimethylsiloxane (PDMS)-coated silica fiber. Optimization of conditions including gas chromatograph injection temperature, microwave extraction power and microwave extraction time are presented. The identification and quantification (via the method of standard additions) of the extracted compounds is carried out by capillary gas chromatography with inductively coupled plasma mass spectrometric detection (GC-ICP-MS) using a unique heated interface that was designed for this work. The SPME-GC-ICP-MS method was validated for the determination of methylmercury (MeHg) concentrations in a variety of biological Standard Reference Materials (SRMs), ranging from 13.2 ng g−1 in SRM 1566b Oyster Tissue, to 397 ng g−1 in SRM 1946 Lake Superior Fish Tissue. Additionally, this method was applied to the determination of MeHg in seabird eggs (common murres, Uria aalge and thick-billed murres, Uria lomvia) collected from colonies on Little Diomede and Bogoslof islands in the Bering Sea and Saint Lazaria Island in the Gulf of Alaska and cryogenically banked in the Marine Environmental Specimen Bank. The results obtained demonstrate that SPME-GC-ICP-MS is a sensitive technique for the determination of methylmercury at trace and ultra-trace levels in a variety of natural matrices with high reproducibility and accuracy. In all instances, the sample-to-sample variability was typically 2% relative standard deviation (RSD) and the method detection limit for methylmercury was 4.2 pg g−1 (as Hg), based on a 0.5 g tissue sample of SRM 1566b Oyster Tissue.