Rapid, one-pot derivatization and distillation of chlorophenols from solid samples with their on-line enrichment

A microwave-assisted steam distillation (MASD) sample preparation technique for extracting chlorophenols from solid samples was studied. This open vessel microwave system based study developed as an integrated method since it has incorporated extractive distillation, derivatization and on-line enrichment. Gas chromatography (GC) with electron-capture detection was used for the analysis. The study involved optimization of MASD parameters and on-line enrichments using spiked solid samples. MASD achieved recoveries for spiked soil samples in the range of 94-101% within 20min with a collection of only 20ml distillate facilitating on-line enrichment. Some real samples were analyzed that included soil, wood, leather, textiles, dyes and certified reference materials of soil and wood samples. Limit of detection values of 12ng/g for pentachlorophenol and 194ng/g for monochlorophenol were found. Recoveries of 96.6% in the case of soil certified reference material (CRM) with RSD 2.7% and 80.6% in the case of wood CRM with RSD 3.3% were observed in this study. MASD studied found to produce very clean extracts in comparison to reference techniques.     

Innovation in a Continuous System of Distillation by Steam to Obtain Essential Oil from Persian Lime Juice (Citrus latifolia Tanaka)

The citrus industry is one of the most important economic areas within the global agricultural sector. Persian lime is commonly used to produce lime juice and essential oil, which are usually obtained by batch distillation. The aim of this work was to validate a patented continuous steam distillation process and to both physically and chemically characterize the volatile fractions of essential Persian lime oil. Prior to distillation, lime juice was obtained by pressing the lime fruit. Afterwards, the juice was subjected to a continuous steam distillation process by varying the ratio of distillate flow to feed flow (0.2, 0.4, and 0.6). The distillate oil fractions were characterized by measuring their density, optical rotation, and refractive index. Gas chromatography GC-FID was used to analyze the chemical compositions of the oil fractions. The process of continuous steam distillation presented high oil recovery efficiencies (up to 90%) and lower steam consumption compared to traditional batch process distillation since steam consumption ranged from 32 to 60% for different steam levels. Moreover, a reduction in process time was observed (from 8 to 4 h). The oil fractions obtained via continuous steam distillation differed significantly in their composition from the parent compounds and the fractions.     

Bestimmung von isomeren 4-Nonylphenolen in B?den

Summary It was reported that 4-nonylphenol isomers had been found in high concentrations in sewage sludge. When this sludge is applied to fields there is a risk that soils may be contaminated with nonylphenols. Therefore, a method is described here for the determination of 4-nonylphenol isomers in soil. The steam distillation/solvent extraction technique is used. An essential part of the method is the clean-up step by column chromatography. The determination is performed on a fused silica capillary by a flame ionization or a mass selective detector. Average recoveries from soil samples spiked with 0.1 to 1 mg/kg ranged from 90 to 116%. The detection limit is 0.1–0.05 mg/kg soil (this limit corresponds to the technical mixture of the isomers).     

Novel Integrated Flow-Based Steam Distillation and Titration System for Determination of Volatile Acidity in Wines

Novel integrated flow-based steam distillation and titration system with spectrophotometric detection was developed for determination of volatile acidity in wines. Using the system, the distillation procedure was carried out in an automatic manner, starting with introducing into a heated steam distillation module a sample and subjecting it to steam distillation. Under selected conditions, all the analyte was transferred to the distillate; therefore, the system did not require calibration. The collected distillate and titrant were introduced into the next monosegments in varying proportions, in accordance with the developed titration procedure, and directed to the detection system to record the titration curve. The titration was stopped after reaching the end point of titration. Procedures for distillation and titration were developed and verified separately by distillation of acetic acid, acetic acid in the presence of tartaric acid as well as acetic acid, tartaric acid, and titratable acidity, with precision (relative standard deviation) and accuracy (relative error) for both procedures lower than 6.9 and 5.6%, respectively. The developed steam distillation and titration systems were used to determine volatile acidity in samples of white and rosé wines separately and as the integrated steam distillation and titration system, both with precision lower than 9.4% and accuracy better than 6.7%.     

Superheated water extraction, steam distillation and SFE of peppermint oil

Superheated water extraction, steam distillation and supercritical fluid extraction (SFE) are compared for extraction of l-menthol, menthone, eucalyptol and other components of peppermint (mentha piperita) leaves. Different temperatures and pressures were investigated. SFE results at 25/40?°C and 6.5/8/10 MPa were comparable with those reported in the literature. Although SFE is a gentle way of extracting thermally unstable compounds, this method is too slow for commercial use in comparison with steam distillation at 100?°C. Superheated water extraction at 125/150?°C and 1–2 MPa exhibits higher extraction efficiency than the SFE method. Comparison of all experiments under the chosen conditions shows steam distillation to be the most effective extraction method.     

蛇油的挥发性成分分析和脱腥

采用水蒸汽蒸馏、黏土吸附、乙醇-乙酸乙酯共沸的方法除去蛇油的腥味,运用顶空固相微萃取(SPME)-气相色谱(GC)-质谱(MS)联用技术分析脱腥前后蛇油中挥发性成分的变化,并运用GC-MS联用技术分析脱腥后的蛇油中的脂肪酸.结果表明水蒸汽蒸馏是效果最佳的脱腥方法,它可使蛇油挥发性成分的量降至脱腥前的38%,使腥味的主要成分减少60%～100%,同时较大程度地保留了多不饱和脂肪酸.     

Microwave accelerated steam distillation of essential oil from lavender: A rapid, clean and environmentally friendly approach

A new process design and operation for microwave accelerated steam distillation (MASD) of essential oils was developed. A packed bed of lavender flowers (Lavandula angustifolia Mill., Lamiaceae) sits above the steam source generated by microwave heating. Only steam passes through it without the boiling water mixing with vegetable raw material, as is the case in hydro-distillation. MASD has been compared with a conventional technique, steam distillation (SD), for the extraction of essential oil from lavender flowers. Extraction of essential oils from lavender with MASD was better than SD in terms of energy saving, rapidity (10 min versus 90 min), product yield, cleanliness and product quality.     

Separation and determination of fluoride in plant samples

A simple and rapid separation method is described for the determination of fluoride in plant samples. Fluoride is separated by distillation in the presence of H(2)SO(4) and H(2)O(2) in a dry air steam. The variables that influence the distillation quantitation were optimized. The fluorides separated were subsequently determined by a spectrophotometric method of the La(III)-F(-)-alizarin complexone system. The precision of the procedure was significant, and the RSD was 3.7%. The accuracy of the method was statistically satisfactory, and the recovery was from 95.9 to 104.4%.     

Rapid analysis of the essential oil components of dried Zanthoxylum bungeanum Maxim by Fe2O3‐magnetic‐microsphere‐assisted microwave distillation and simultaneous headspace single‐drop microextraction followed by GC–MS

In this work, microwave distillation assisted by Fe₂O₃ magnetic microspheres (FMMS) and headspace single‐drop microextraction were combined, and developed for determination of essential oil compounds in dried Zanthoxylum bungeanum Maxim (ZBM). The FMMS were used as microwave absorption solid medium for dry distillation of dried ZBM. Using the proposed method, isolation, extraction, and concentration of essential oil compounds can be carried out in a single step. The experimental parameters including extraction solvent, solvent volume, microwave power, irradiation time, and the amount of added FMMS, were studied. The optimal analytical conditions were: 2.0 μL decane as the extraction solvent, microwave power of 300 W, irradiation time of 2 min, and the addition of 0.1 g FMMS to ZBM. The method precision was from 4 to 10%. A total of 52 compounds were identified by the proposed method. The conventional steam distillation method was also used for the analysis of essential oil in dried ZBM and only 31 compounds were identified by steam distillation method. It was found that the proposed method is a simple, rapid, reliable, and solvent‐free technique for the determination of volatile compounds in Chinese herbs.     

Application of PLE for the determination of essential oil components from Thymus vulgaris L

Essential plants, due to their long presence in human history, their status in culinary arts, their use in medicine and perfume manufacture, belong to frequently examined stock materials in scientific and industrial laboratories. Because of a large number of freshly cut, dried or frozen plant samples requiring the determination of essential oil amount and composition, a fast, safe, simple, efficient and highly automatic sample preparation method is needed.Five sample preparation methods (steam distillation, extraction in the Soxhlet apparatus, supercritical fluid extraction, solid phase microextraction and pressurized liquid extraction) used for the isolation of aroma-active components from Thymus vulgaris L. are compared in the paper. The methods are mainly discussed with regard to the recovery of components which typically exist in essential oil isolated by steam distillation.According to the obtained data, PLE is the most efficient sample preparation method in determining the essential oil from the thyme herb. Although co-extraction of non-volatile ingredients is the main drawback of this method, it is characterized by the highest yield of essential oil components and the shortest extraction time required. Moreover, the relative peak amounts of essential components revealed by PLE are comparable with those obtained by steam distillation, which is recognized as standard sample preparation method for the analysis of essential oils in aromatic plants.     

Physical and chemical changes of medicinals in mixtures with adsorbents in the solid state. III. Determination of vapor pressure of solid drugs by steam distillation

The vapor pressures of solid drugs were determined by the steam distillation method. Experiments using a series of benzoic acid derivatives indicated that this method offered consistent and satisfactory values for vapor pressure at about 100 degrees C. The vapor pressures of two nonsteroidal antiinflammatory drugs, flufenamic acid (FFA) and mefenamic acid (MFA), were found to be 3.8 x 10(-3) and 1.8 x 10(-4) mmHg, respectively. These values explain the difference in the rate of change to the amorphous state between mixtures of each with magnesium aluminum silicate (MAS) when they were stored under reduced pressure. It was concluded that the vapor pressures of solid drugs at about 100 degrees C, as determined by steam distillation, may be suitable indices for predicting whether or not these drugs have an inherent propensity to become amorphous readily in mixtures with an adsorbent.     

Superheated water extraction, steam distillation and SFE of peppermint oil

Superheated water extraction, steam distillation and supercritical fluid extraction (SFE) are compared for extraction of l-menthol, menthone, eucalyptol and other components of peppermint (mentha piperita) leaves. Different temperatures and pressures were investigated. SFE results at 25/40 °C and 6.5/8/10 MPa were comparable with those reported in the literature. Although SFE is a gentle way of extracting thermally unstable compounds, this method is too slow for commercial use in comparison with steam distillation at 100 °C. Superheated water extraction at 125/150 °C and 1–2 MPa exhibits higher extraction efficiency than the SFE method. Comparison of all experiments under the chosen conditions shows steam distillation to be the most effective extraction method. Received: 18 January 1998 / Revised: 9 April 1999 / Accepted: 15 April 1999     

Determination of Xenoestrogens Alkylphenols in Oyster and Snail Tissues by Extractive Steam Distillation and Gas Chromatography‐Mass Spectrometry

A simple and sensitive method is presented for the determination of two well‐known xenoestrogens alkylphenols (4‐tert.‐octylphenol (4‐t‐OP) and 4‐nonylphenol isomers (4‐NPs)) in oysters and snails. The method involves extraction of the sample by a modified Nielson‐Kryger steam distillation extraction, and the alkylphenols were then identified and quantitated by gas chromatography‐mass spectrometry (GC‐MS) in selected ion monitoring (SIM) mode. The quantitation limit of this method was less than 20 ng/g in 0.5 g (dry weight) of the samples. The perfect applicability of the steam distillation extraction method for 4‐t‐OP and 4‐NPs was determined after testing it with spiked and real samples. Recovery of 4‐t‐OP and 4‐NPs in spiked tissue samples was above 88% while relative standard deviation (RSD) ranged from 7 to 14%. 4‐tert.‐octylphenol and 4‐nonylphenol isomers are ubiquitous in oysters and snails with the concentrations of 4‐t‐OP and 4‐NPs ranging from 70 to 820 ng/g and from 210 to 2750 ng/g (dry weight), respectively.     

Highly volatile constituents of Vetiveria zizanioides roots grown under different cultivation conditions

Roots of Vetiveria zizanioides Nash (Mae Hae; Thai ecotype) planted in three different cultivation systems (normal soil, normal soil with added microbes and semi- hydroponically) were extracted using a simultaneous steam distillation and solvent extraction (SDE) apparatus. Yields of the essential oils obtained were 0.27, 0.18 and 0.06%, respectively. The separation profiles obtained by comprehensive two-dimensional gas chromatography (GCxGC) and solid phase microextraction (SPME)-GCxGC analyses of the crude essential oils showed a total of 156 and 48 well-resolved components, respectively. The highly volatile fractions isolated from the three essential oils by SPME were subjected to analysis by GC-MS and 42 compounds were identified in total. Volatile component profiles of the oils obtained by normal soil and semi-hydroponic cultivation were similar, whereas a quantitative difference was noted in some major volatiles when the cultivation system containing microbes was utilized.     

Water as a green solvent combined with different techniques for extraction of essential oil from lavender flowers

Using water as a green solvent with a variable geometry makes use of physical and chemical phenomena that are fundamentally different from those applied in conventional extraction techniques such as hydro-distillation, steam distillation or solvent extraction. Advantages and drawbacks of using water as a solvent with different physical and chemical states have been compared. A total of ten extraction techniques: hydro-distillation (HD), steam distillation (SD), turbo-hydro-distillation (THD), salt-hydro-distillation (NaCL-HD), enzyme-hydro-distillation (Enzyme-HD), micelle-hydro-distillation (Micelle-HD), ultrasound-hydro-distillation (US-HD) or subcritical water-hydro-distillation (SW-HD), solvent-free microwave extraction (SFME) and microwave steam distillation (MSD) were used to extract the essential oil from lavender (Lavandula L.) and their results were compared. The quantity was measured by the yield of essential oil and the quality was evaluated using the oil composition especially the content of linalyl acetate, linalool and terpin-4-ol compared with the corresponding control sample: Hydro-distillation. For environmentally friendly of the process: extraction time, total energy consumption and CO₂ emission were considered and compared with conventional hydro-distillation. The mechanism explaining the linalyl acetate degradation has been resolved by using COSMO-RS software. Based on the present experimental conditions, it is recommended that lavender oil may be produced preferably by steam distillation assisted by microwave extraction to reduce the by-product formation by various chemical reactions and to get better oil recoveries.     

Ultrasound-assisted dynamic extraction of valuable compounds from aromatic plants and flowers as compared with steam distillation and superheated liquid extraction

A method for the extraction of valuable compounds from plants and flowers (viz. laurel, rosemary, thyme, oregano and tuberose) is proposed. The dynamic approach allows go-and-backward circulation of the extractant (ethanol) through the solid sample subjected to the action of an ultrasound probe (thus reducing sample amount and avoiding overpressure). A multivariate optimisation study and application of the optimum values of the variables to kinetics studies show that 10 min is sufficient to obtain extraction efficiencies that greatly surpass those provided by steam distillation for essential oils or superheated liquid extraction for these oils and other valuable compounds, with lower costs and higher quality of the extract. The extraction time of the proposed method is 176–165 min shorter than steam distillation and 31–20 min shorter than superheated liquid extraction, depending on the target compound.     

北苍术超临界CO2萃取产物的成分

用气相色谱－质谱－计算机联用法分析了北苍术的超临界CO2萃取产物的成分,鉴定出苍术酮、β－桉叶油醇、苍术醇31化合物,占出峰总面积的88．1％,并与传统水蒸汽蒸馏法（SD）提取的挥发油成分进行了对比。结果证明,两种方法抽提的苍术主成分基本相同,但超临界CO2萃取产物比SD产物多出现了一些重质组分,萃取更完全而有效。     

兴安落叶松针叶挥发油的GC-MS和启发渐进式特征投影法分析

采用水蒸气蒸馏法提取兴安落叶松针叶挥发油,利用气相色谱.质谱(GC-MS)联用对挥发油进行成分测定,并对其重叠色谱峰采用启发渐进式特征投影(HELP)法进行分辨,得到各组分的纯色谱峰和质谱,然后采用峰面积归一化法确定各化合物的相对含量.共分离出110种化合物,鉴定了70种化合物,占挥发油总量的93.09%,其中单萜、倍半萜和二萜的含量分别为31.92%、53.29%和6.91%.     

碱蒸馏/超声波衍生化-气相色谱-质谱法测定土壤中的偏二甲肼

建立了碱蒸馏/超声波衍生化预处理的气相色谱-质谱法测定土壤中偏二甲肼的分析方法。通过碱蒸馏预处理方法,以水杨醛为衍生化试剂,采用超声波加速衍生化反应,在选择离子检测( SIM)模式下进行定量分析,衍生化产物的特征离子为m/z 164。考察了碱蒸馏、超声波衍生化条件的影响,并对衍生化条件进行优化,方法的线性范围在0.4~30 mg/L之间,方法检出限为0.0078 mg/kg。以此方法测定已知浓度的土壤样品,目标化合物的含量在10~100 mg/kg之间,回收率在76％~108％之间,相对标准偏差在12％~19％之间。与分光光度法、索氏提取/超声波衍生化-气相色谱-质谱法相比较,本方法检出限显著优于二者。     

Zur Bestimmung von Ammoniak in Lebensmitteln

Controlling the steam distillation which was used for ammonia determination applying normal pressure, we could state that food containing protein did release ammonia even in the presence of very little alkali (pH 7,4). By using steam distillation with magnesium oxide, for mild alkalisation, the amounts of ammonia were lower than with buffer solutions of the same alkalinity; comparatively, with buffer solutions of lower alkalinity magnesium oxide causes a higher amount of ammonia. These effects are mainly caused by the influence of the (boiling-)temperature of 100° C; besides of this the amounts of ammonia obtained are depending not only on the type of substance and alkalinity of the solution, but also on the intensity of heating and the duration of the distillation. Variations in the relationship between the amount of sample and the solution for alkalisation effect a change of alkalinity and by this always different yields of ammonia. Therefore, this method cannot be acknowledged for determinations of ammonia in substances containing easily decomposable protein compounds, even not under fixed conditions.