Determination of seven polycyclic aromatic hydrocarbons in water by dispersive liquid-liquid microextraction based on solidification of floating organic droplet with gas chromatography-mass spectrometry / 上海预防医学

Objective To develop a new method for the simultaneous determination of seven polycyclic aromatic hydrocarbons(PAHs)in water by dispersive liquid-liquid microextraction based on solidification of floating organic droplet(DLLME-SFO)with gas chromatography-mass spectrometry(GC-MS). Methods The experimental conditions of DLLME-SFO were determined with dodecanol as extractant solvent, methanol as dispersive solvent, inonic strength increased by adding 8% NaCl. After vortexed for 1 min and centrifuged at 4 000 r/min for 5 min, the water sample was cooled down in an ice bath till dodecanol became solid and formed a small ball. Then the solidified dodecanol phase was transferred, and directly detected by GC-MS method after it melted. Results Good linearities were obtained for the seven polycyclic aromatic hydrocarbons within the range of 5 μg/L-200 μg/L. The correlation coefficients were above 0.996. The detection limits ranged from 1.6 ng/L to 3.2 ng/L. The average recoveries ranged from 86.2% to 105% and the RSDs from 3.8% to 9.4%. Conclusion The method is sensitive, fast and simple. It has the advantage of little organic solvent consumption, which is friendly to environment and suitable for the detection of seven PAHs in water.

Dispersive liquid-liquid microextraction,an effective tool for the determination of synthetic cannabinoids in oral fluid by liquid chromatography-tandem mass spectrometry / 药物分析学报

In the present work,dispersive liquid-liquid microextraction (DLLME) was used to extract six synthetic cannabinoids (JWH-018,JWH-019,JWH-073,JWH-200,or WIN 55,225,JWH-250,and AM-694) from oral fluids.A rapid baseline separation of the analytes was achieved on a bidentate octadecyl silica hydride phase (Cogent Bidentate C18;4.6 mm × 250 mm,4 μm) maintained at 37℃,by eluting in isocratic conditions (water:acetonitrile (25:75,V/V)).Detection was performed using positive electrospray ionization-tandem mass spectrometry.The parameters affecting DLLME (pH and ionic strength of the aqueous phase,type and volume of the extractant and dispersive solvent,vortex and centrifugation time)were optimized for maximizing yields.In particular,using 0.5 mL of oral fluid,acetonitrile (1 mL),was identified as the best option,both as a solvent to precipitate proteins and as a dispersing solvent in the DLLME procedure.To select an extraction solvent,a low transition temperature mixture (LTTM;composed of sesamol and chlorine chloride with a molar ratio of 1:3) and dichloromethane were compared;the latter (100 μL) was proved to be a better extractant,with recoveries ranging from 73％ to 101％ by vortexing for 2 min.The method was validated according to the guidelines of Food and Drug Administration bioanalytical methods:intra-day and inter-day precisions ranged between 4 ％ and 18 ％depending on the spike level and analyte;limits of detection spanned from 2 to 18 ng/mL;matrix-matched calibration curves were characterized by determination coefficients greater than 0.9914.Finally,the extraction procedure was compared with previous methods and with innovative techniques,presenting superior reliability,rapidity,simplicity,inexpensiveness,and efficiency.

Determination of Escitalopram in Biological Samples by Dispersive Liquid-Liquid Microextraction Combined with GC-MS/MS / 法医学杂志

Objective To establish a method for determination of escitalopram in biological samples by ultrasound-assisted ionic liquid-dispersive liquid-liquid microextraction combined with gas chromatography-tandem mass spectrometry （GC-MS/MS） and provide evidences for forensic determination of cases related to escitalopram. Methods The 1-hexyl-3-methylimidazolium hexafluorophosphate （[C6MIM][PF6]） was selected as an extract solvent to process biological samples. Ultrasound-assisted extraction was used on the samples. Then the samples were detected by GC-MS/MS. Results The linear range of escitalopram in blood and liver were 5.56-1 111.10 ng/mL and 0.025-5.00 mg/g, respectively. The correlation coefficient （r） were greater than 0.999, limit of detection （LOD） were 4.00 ng/mL and 2.00 μg/g, limit of quantitation （LOQ） were 14.00 ng/mL and 6.00 μg/g, respectively. The extraction recovery rates were all greater than 50%, the interday and intraday precision were less than 20%. Escitalopram was detected in blood and liver samples from the actual poisoning case by this method with a content of 1.26 μg/mL and 0.44 mg/g, respectively. Conclusion The ultrasound-assisted ionic liquid-dispersive liquid-liquid microextraction combined with GC-MS/MS is environment friendly, rapid, has good enriching effect and consumes less organic solvent and can be used for forensic determination of escitalopram related cases.

Evaluation of Dunaliella salina growth and corresponding ß-carotene production in tubular photobioreactor / Avaliação do crescimento da Dunaliella salina e correspondente produção de ß-caroteno em fotobiorreator tubula

Microalgae, photosynthetic microorganisms, are rich in lipids, polyunsaturated fatty acids, carbohydrates, proteins, vitamins, as well as carotenoids, which are antioxidants that may protect human body from various diseases including obesity, cardiovascular disease, vision-related diseases such as macular degeneration and certain types of cancer. These natural pigments have applications in the pharmaceutical (nutraceutical), food (coloring, functional food, and supplements), and cosmetics industries (e.g. sunscreen), as well as in aquaculture (animal feed). The Dunaliella salina microalga can synthesize 10% of dry weight in ß-carotene (orange pigment, pro-vitamin A activity) under high light intensity and nitrogen and phosphorus limitation, among other stress conditions. The first chapter of this thesis presents a review focused on microalgae carotenoids: culture systems, mode of operation, and applications. In this bibliographic survey, the advantages of microalgae cultivation in relation to traditional sources (higher plants) were discussed, as well as a discussion of the main cultivation systems and their importance in cell growth. This review presented a critical analysis of the different operational regimes like batch, fed-batch, semi-continuous and continuous. Relevant information on the most important world producers of microalgae carotenoids were presented. Chapter II presents the development of a modified method of dispersive liquid-liquid microextraction (DLLME) for rapid extraction of ß-carotene from Dunaliella salina cultivated in tubular photobioreactor, with subsequent development of a rapid chromatographic screening method using a C4 column for separation of geometric isomer of ß-carotene. The use of benzene as extraction solvent and water with 50% acetone as dispersant provided the best condition for the extraction of this carotenoid. In HPLC (High Performance Liquid Chromatography), employing mobile phase composed of methanol and water (95:5, v/v), it was possible to detect/quantify ß-carotene at 14 min (retention time). Besides the short analysis time (<20 min), by the miniaturized extraction (< 10 mL organic waste) this method abide by green chemistry analytical principles. It is known that nitrogen, phosphorus, as well as carbon and vitamins are vital elements for the growth of microalgae, also determining the biochemical composition of biomass. In this sense, Chapter III presents the study of the influence of different amounts of sodium nitrate (1N = 75 mg L-1; 1.5N = 112.5 mg L-1, and 3N = 225 mg L-1) and phosphate monobasic dehydrate (1P = 5.65 mg L-1, 1.5P = 8.47 mg L-1, and 3P = 16.95 mg L-1) in seawater-based f/2 medium on the growth of Dunaliella salina and ß-carotene biosynthesis, by continuous process with different replenishment proportions (R = 20% and 80%). Best results of cell productivity were obtained by semicontinuous process (mean values of Px up to 6.7 x 104 cells mL-1 d-1 with medium 1N:1P; R =20%) in comparison with batch process cultivation. Maximum cell density (Xm) obtained in this work was not dependent of R, but the best results were obtained when using medium 1.5N:1.5P (mean values up to 5.6 x 105 cells mL-1 with R =80%) instead of 1N:1P. The content of ß-carotene in the cells, in general, was higher in cells grown in medium 1N:1P (mean yield values up to 57.5 mg g-1 with R =80%) in comparison with medium 1.5N:1.5P. The cultivation of D. salina with media 3N:3P led to a long lag phase, followed by decrease in cell density and cell lysis. The use of a tubular photobioreactor contributed to successfully cultivate this microalga without contamination by protozoa. The cultivation of Dunaliella salina in tubular photobioreactor with the use of 12:12 photoperiod was appropriate, as well as to induce carotenogenesis, in the second stage, by increasing the light intensity and absence of pH control

As microalgas, micro-organismos fotossintetizantes, são ricas em lipídios, ácidos graxos poli-insaturados, carboidratos, proteínas, vitaminas, além de carotenoides que são antioxidantes com potencial de proteger o organismo humano de várias doenças incluindo a obesidade, doenças cardiovasculares, doenças relacionadas à visão como a degeneração macular e certos tipos de câncer, entre outras. Esses pigmentos naturais têm aplicações em indústrias farmacêuticas (nutracêuticos), alimentícias (colorantes, alimentos funcionais e suplementos) e de cosméticos (exemplo: filtro solar) e na aquacultura (ração animal). A microalga Dunaliella salina é capaz de sintetizar, sob alta intensidade luminosa e limitação de nutrientes como fontes de fósforo e nitrogênio, dentre outras condições de estresse, 10 % do peso seco em ß-caroteno (pigmento laranja com atividade pró-vitamina A). Assim, neste trabalho, numa primeira etapa, foi feita uma revisão da literatura abordando a produção de carotenoides por microalgas, bem como sua aplicação. Nesse levantamento bibliográfico abordou-se, dentre outros assuntos, as vantagens do cultivo de microalgas em relação as fontes tradicionais (plantas superiores), assim como uma discussão dos diferentes sistemas de cultivos e sua importância no crescimento celular. Esse review apresentou uma análise crítica dos principais regimes operacionais como batch, fed-batch, semicontínuo e contínuo. Apresentou-se também informações relevantes sobre os mais importantes produtores mundiais de carotenoides de microalgas. Numa segunda etapa, foi desenvolvido um método modificado de microextração líquido-líquido dispersivo modificado (DLLME) para a rápida extração de ß-caroteno de Dunaliella salina cultivada em fotobiorreatores tubulares, com subsequente desenvolvimento de método cromatográfico em uma coluna C4 para a separação do isômero geométrico de ß-caroteno. A extração ótima de ß-caroteno foi obtida com benzeno como solvente extrator e água com 50% de acetona como dispersante. Empregando uma fase móvel composta por metanol e água (95:5, v/v) em HPLC, foi possível a detecção/quantificação de ß-caroteno com 14 minutos de tempo de retenção. Além dos tempos curtos de análises (<20 min), pela extração em volume reduzido (< 10 mL resíduos orgânicos) este método obedece aos princípios da química verde. Sabe-se que nitrogênio, fósforo, assim como carbono e vitaminas são elementos vitais para o crescimento das microalgas e também exercem influência na composição bioquímica da biomassa. Assim, na terceira etapa deste trabalho, estudou-se a influência das quantidades de nitrato de sódio (75 mg L-1, denominado 1N; 112,5 mg L-1, denominado 1,5N; 225 mg L-1, denominado 3N) e de fosfato monobásico dihidratado (5,65 mg L-1, denominado 1P; 8,47 mg L-1, denominado 1,5P; 16,95 mg L-1, denominado 3P) em meio f/2, que tem como base a água do mar, no crescimento e na síntese de ß-caroteno da Dunaliella salina por processo semicontínuo, com uso de frações de corte (R) de 20% e 80%. Foram obtidas produtividades celulares mais elevadas em processos semicontínuos do que em processo descontínuo, com produtividades médias de até 6,7 x 104 células mL-1 d-1 (meio 1N:1P; R =20%). A máxima concentração celular (Xm) obtida neste trabalho não foi dependente de R. Os melhores resultados de Xm foram obtidos quando se usou meio 1,5N:1,5P em vez de meio, com 1N:1P, com valores médios de até 5,6 x 105 células m L-1 (R =80%). O conteúdo de ß-caroteno nas células, de maneira geral, foi maior nas células cultivadas em meio 1N:1P do que no meio 1,5N:1,5P, com valores até 57,5 mg g-1 (R =80%). O cultivo de D. salina com o meio 3N:3P levou a uma longa fase lag, seguida por uma diminuição na concentração celular e sua lise. O cultivo de células em um fotobiorreator tubular contribuiu para um crescimento celular sem contaminação por protozoários. O cultivo de Dunaliella salina em fotobiorreator tubular com o uso de fotoperíodo 12:12 foi apropriado, assim como induzir a carotenogênese, no segundo estágio, por meio do aumento da intensidade luminosa e ausência de controle de pH

Purification and Enrichment of Polycyclic Aromatic Hydrocarbons Pollutions in Oil-Field Water by Column Clean-up Coupled with Dispersive Liquid-Liquid Microextraction / 分析化学

A sample pretreatment method combining column clean-up with dispersive liquid-liquid microextraction (CCU-DLLME) for determination of polycyclic aromatic hydrocarbons (PAHs) in oil-field water was proposed. With this method,most organic interferences in matrix were cleaned up,and PAHs were purified, enriched and analyzed by gas chromatography/mass spectrometry directly. The influences on extraction efficiency including the kinds of column packing,weight ratio between column packing and sample, column flow rate,type and volume of extraction solvent, type and volume of disperser solvent and extraction time were investigated, respectively. Finally, 12 g of H103 macroporous resin was selected as column packing,12﹕5 of weight ratio between column packing and sample and 4 BV/h of column flow rate were selected in CCU. The resulting eluate was added with 1.00 mL of acetone (disperser solvent) and 15 μL of carbon tetrachloride (extraction solvent),followed by DLLME for 2 min. Under the optimum conditions,the enrichment factor of PAHs was 730-1579,the limits of detection (S/N=3) were 1.1-5.3 ng/L, the linear range was 0.01-50 μg/L,the RSDs(n=5) were 0.6%-3.4% and the recoveries were 82.6%-104.6%. This method could greatly reduce the influence of organic interferences in matrix, and was fit for the rapid analysis of pollutants in oil-field water especially.

Rapid Determination of Six Pesticides in Water Samples Using Ultrasound-assisted Dispersive Liquid-Liquid Microextraction Coupled with High Performance Liquid Chromatography / 分析化学

A novel method for accurate,fast and sensitive detection of pesticides such as imidacloprid,isocarbophos,phoxim,dursban,imidacloprid,pyridaben and avermectin in environmental water samples has been developed by using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) coupled with high performance liquid chromatography with ultraviolet detection (HPLC-UV).The UA-DLLME parameters such as types/volumes of extraction/dispersion solvents,ultrasonic time,ionic strength and extraction time were investigated.Under the optimized extraction conditions,the linearity for the detection of six pesticides in the concentration range of 10-600 μg/L was obtained with limits of detections (LODs) of 0.8-3.1 μg/L and relative standard deviations (RSDs) of 4.7％-11.3％.UA-DLLME method exhibited strong enrichment ability for the six pesticides,and the enrichment factor (EFs) were ranged from 58 to 187.This method had perfect linearity,precision and recovery results,and showed obvious advantages and practicality comparing the previously reported methods.

Determination of 15 Kinds of Nitroaromatics in Aqueous Samples Using Dispersive Liquid-Liquid Microextraction and Gas Chromatography with Electron Capture Detection / 分析化学

A method for the determination of 15 kinds of nitroaromatics in aqueous samples was developed by dispersive liquid-liquid microextraction and gas chromatography with electron capture detection. A high-density extractant applied in electron capture detector was screened out. The chromatographic conditions, types and dosages of extractants, types and dosages of dispersants, extraction time and the extraction temperature were optimized. The results showed that DB-35 capillary column had the best separation performance for the 15 kinds of nitroaromatics. The nitroaromatics could be separated within 22 min using programmed temperature control as follows: holding at an initial temperature of 80℃ and then heating to 180℃ at a ramping rate of 5℃ / min. For the extraction of 15 kinds of nitroaromatics from 5 mL of aqueous sample, the extraction equilibrium could be reached within 30 s with a high extraction recovery of over 90%when using 100 μL of chlorobenzene as extracting solvent and 400 μL of methanol as disperser solvent. In addition, the enrichment factor could approach a high value of 45. 0 - 48. 8. The sediment collected by centrifugation was injected and analyzed by gas chromatography with electron capture detector. The limits of quantification of the developed method were 0. 03 - 0. 15 μg / L ( S / N = 10). The linear range was from 0. 20 μg / L to 50. 0 μg / L, while the correlation coefficients (R2 ) were more than 0. 998. At the spiked level of 0. 200 μg / L, the relative standard deviations of this method were 3. 3% -8. 9% , the relative recoveries ranged from 86. 0% to 103. 5% . At higher spiked level, the relative standard deviations were less than 5% , and the relative recoveries ranged from 94. 5% to 101. 5% .

Benzyl Functionalized Ionic Liquid as New Extraction Solvent of Dispersive Liquid-liquid Microextraction for Enrichment of Organophosphorus Pesticides and Aromatic Compounds / 分析化学

A benzyl functionalized ionic liquid, 1-benzyl-3-methylimidazolium bis [( trifluoromethyl ) sulfonyl]imide ([BeMIM][Tf2 N]), was synthesized and characterized as an extraction solvent of dispersive liquid-liquid microextraction ( DLLME) for enrichment and determination of 5 organophosphorus pesticides (phoxim, fenitrothion, chlorpyrifos, phorate and parathion) and 2 aromatic compounds (chloronaphthalene and anthracene) from environmental water samples by high-performance liquid chromatography ( HPLC). [BeMIM] [ Tf2 N] had higher extraction efficiency than 1-octyl-3-methylimidazolium bis [( trifluoromethyl) sulfonyl]imide and common organic solvents such as CCl4 and C2 Cl4 . The extraction was performed using 40 μL of [BeMIM][Tf2N] and 1 mL of methanol as extraction solvent and dispersive solvent respectively with centrifugal time of 5 min. Under the optimal conditions, the method proposed here provided a good linearity for all analytes with correlation coefficients between 0. 9994 and 0. 9998. The repeatability values, described as intra-day and inter-day relative standard deviations (RSDs) of five replicate experiments at three different concentrations of 10, 40 and 100 μg / L, were 1. 1% -4. 3% and 0. 8% -4. 8% , respectively. The limits of detection (LOD) were 0. 01 μg / L-1. 0 μg / L at a signal-to-noise ratio (S / N) of 3. This developed method was convenient and speedy, and could be employed to detect the analytes in three real environmental water samples with satisfactory relative recovery of 82. 7% -118. 3% and RSD of 0. 7% -5. 6% . Introduction of benzyl group into the imidazolium could obviously enhance the extraction efficiecny for analytes due to the π-πinteraction between [BeMIM] [ Tf2 N] and analytes. [ BeMIM] [ Tf2 N] was a satisfactory extraction solvent with a high enrichment factor of 339 and extraction efficiency of 81. 4% . Partition coefficients of all analytes in [BeMIM][Tf2 N]-DLLME system were determined and the extraction mechanism was discussed.

Simultaneous Determination of Toxic Alkaloids and Rat Poisons in Toxic Samples by Dispersive Liquid-liquid Micro-extraction Combined with Gas Chromatography-Mass Spectrometry / 分析化学

A novel method for simultaneous determination of 3 rat poisons ( tetramine, bromadiolone, brodifacoum) and 5 toxic alkaloids ( hyoscyamine, scopolamine, gelsemine, strychnine, brucine ) in toxic samples by dispersive liquid-liquid micro-extraction ( DLLME ) coupled with gas chromatography-mass spectrometry was established. A mixture extractant containing 100 μL trichloromethane and 600 μL methanol was injected into the prepared sample to form an emulsion and the extraction process was accomplished. After centrifuged at 8000 r/min for 5 min, the settled drop of trichloromethane solvent was transferred to a conical insert within a GC autosampler vessel, and analyzed by GC-MS. Factors affecting extraction efficiency such as the type and volume of extractant, dispersive agent, extraction time, pH value and salt concentration of extraction system were studied. The limits of detection(LODs) were from 0. 003 to 1 μg/L in water sample, urine sample and rice wine sample. LODs were from 0. 002 to 0. 2 μg/kg in rice sample. The recoveries of toxic samples were in the range of 81. 0%-110%. The relative standard deviations( RSDs) were lower than 7%. The proposed method was sensitive, effective, and suitable for the simultaneous determination of toxic alkaloids and rat poisons in food poisoning sample.

Rapid and Highly Sensitive Analysis of Antioxidants in Edible Oils with Dispersive Liquid-Liquid Microextraction Prior to Gas Chromatography-Tandem Mass Spectrometry / 分析化学

A novel, simple and highly sensitive method was developed for the rapid analysis of phenolic antioxidants at trace level in edible oils. It was based on dispersive liquid-liquid microextraction ( DLLME ) and gas chromatography-mass/mass spectrometry ( GC-MS/MS) . Related important factors that may influence enrichment efficiency, such as type and volume of extraction solvent, type and volume of dispersive solvent, and extraction time were investigated and optimized in detail. The optimum conditions were as follows:a quick injection of 500 μL mixed solution ( methanol:acetonitrile=1:1 , V/V ) into 1 . 0 g oil sample with 3 mL n-hexane for 10 s of extraction time. Under the optimal conditions, the linearity (10-2000 ng/g), limits of detection (1. 5-2. 4 ng/g) and relative standard deviations (4. 0%-8. 3%) was obtained. The proposed method was applied for the analysis of 4 edible oil samples. Some of phenolic antioxidants were detected in three of them, and the recoveries of spiked samples were in the range of 81. 9%-118%.

Determination of Methylmercury in Seafood after Dispersive Liquid-liquid Microextraction by Direct Mercury Analyzer / 分析化学

A method for the determination of methylmercury in seafood has been developed using dispersive liquid-liquid microextraction followed by direct mercury analyzer. Total mercury was detected by direct mercury analyzer, and inorganic mercury was calculated by the difference. The parameters affecting the extraction efficiency, including the selection of extractant and dispersant, their volume ratio, concentration of HCl and NaCl have been optimized in this study. The results showed that CH2 Cl2 as extractant, ethanol as dispersant, Volume ration of 1:5, 1 mol/L HCl and 120 g/L NaCl were chosen. The detection limit and the dynamic liner range were 0. 10 μg/L and 0. 2-20 μg/L, respectively. The relative standard deviation was 6. 0% for eleven replicates at the spiked level of 2. 0 μg/L. The enrichment factor was 8. For total Hg determination, the detection limit and the dynamic liner range for methylmercury were 0. 10 μg/kg and 0. 2-50 μg/kg, respectively. The relative standard deviation was 2. 4%. The method was simple, fast and a little solvent needed. Some certified reference materials were analyzed to validate the accuracy of the proposed method, and the results were in good agreement with the reference value. Besides, the method was applied to the real samples with satisfactory results.

Analysis of 5 Dyes Residues in Navel Orange with Temperature-assisted Ionic Liquid Dispersive Liquid-liquid Microextraction and High Performance Liquid Chromatography Detection / 分析化学

A fast method composed of the quick, easy, cheap, effective, rugged and safe ( QuEChERS) and temperature-assisted ionic liquid dispersive liquid-liquid microextraction ( TA-IL-DLLME) sample preparation coupled with high performance liquid chromatography ( HPLC ) for the analysis of 5 dyes residues in navel orange was developed. The QuEChERS sample preparation involved the quick extraction with acetonitrile in the presence of anhydrous MgSO4 and NaCl and the purification with primary secondary amine ( PSA ) sorbent. The TA-IL-DLLME sample preparation was processed using 1 mL of the extract obtained by QuEChERS as dispersive solvent and 60 μL of 1-octyl-3-methylimidazolium hexafluorophosphate as extractive solvent under 55 ℃ of water-bath temperature and 12 min of water-bath time. The ultimate solution was detected by HPLC-UV and the contaminated sample was further confirmed by UPLC-MS/MS under multiple reactions monitoring (MRM) mode. The recoveries of five dyes were in the range from 70. 3% to 93. 6% at two spike levels of 0. 01 and 0. 05 mg/kg, the relative standard deviations (RSDs) were between 3. 5% and 9. 2% and the limits of quantification (LOQs) were between 1. 1 and 2. 8 μg/kg.

Analysis of chlorpheniramine in human urine samples using dispersive liquid-liquid microextraction combined with high-performance liquid chromatography

A simple and environmentally friendly microextraction technique was used for determination of chlorpheniramine (CPM), an antihistamine drug, in human urine samples using dispersive liquid-liquid microextraction (DLLME) followed by high performance liquid chromatography with diode array detection (HPLC-DAD). In this extraction technique, an appropriate mixture of acetonitrile (disperser solvent) and carbon tetrachloride (extraction solvent) was rapidly injected into the urine sample containing the target analyte. Tiny droplets of extractant were formed and dispersed into the sample solution and then sedimented at the bottom of the conical test tube by centrifugation. Under optimal conditions, the calibration curve was linear in the range of 0.055-5.5 µg mL-1, with a detection limit of 16.5 ng mL-1. This proposed method was successfully applied to the analysis of real urine samples. Low consumption of toxic organic solvents, simplicity of operation, low cost and acceptable figures of merit are the main advantages of the proposed technique.

Utilizou-se uma técnica de microextração simples e ambientalmente amigável para a determinação de clorfeniramina (CPM), anti-histamínico, em amostras de urina humana, utilizando a microextração dispersiva líquido-líquido (DLLME), seguida por cromatografia líquida de alta eficiência com detecção por arranjo de diodos (HPLC-DAD). Nesse método de extração, mistura apropriada de acetonitrila (solvente dispersor) e tetracloreto de carbono (solvente de extração) foi injetada rapidamente na amostra de urina contendo o analito alvo. As pequenas gotículas de agente de extração foram formadas e dispersas na solução da amostra e, em seguida, sedimentadas no fundo do tubo cônico de ensaio por centrifugação. Em condições ótimas, a curva de calibração foi linear no intervalo entre 0,055 e 5,5 µg mL-1, com limite de detecção de 16,5 ng mL-1. O método proposto foi aplicado com sucesso na análise de amostras de urina reais. Baixo consumo de solventes orgânicos tóxicos, simplicidade de operação, baixo custo e figuras de mérito aceitáveis são as principais vantagens do método sugerido.

Dispersive Liquid-liquid Microextraction Combined with High-performance Liquid Chromatography for the Determination of Clozapine and Chlorpromazine in Urine / 华中科技大学学报（医学）（英德文版）

A simple method has been proposed for the determination of clozapine (CLZ) and chlorpromazine (CPZ) in human urine by dispersive liquid-liquid microextraction (DLLME) in combination with high-performance liquid chromatography-ultraviolet detector (HPLC-UV).All important variables influencing the extraction efficiency,such as pH,types of the extraction solvent and the disperser solvent and their volume,ionic strength and centrifugation time were investigated and optimized.Under the optimal conditions,the limit of detection (LODs) and quantification (LOQs) of the method were 13 and 39 ng/mL for CLZ,and 2 and 6 ng/mL for CPZ,respectively The relative standard deviations (RSDs) of the targets were less than 5.1％ (C=0.100 μg/mL,n=9).Good linear behaviors over the tested concentration ranges were obtained with the values of R2＞0.999 for the targets.The absolute extraction efficiencies of CLZ and CPZ from the spiked blank urine samples were 98.3％ and 97.8％,respectively.The applicability of the technique was validated by analyzing urine samples and the mean recoveries for spiked urine samples ranged from 93.3％ to 105.0％.The method was successfully applied for the determination of CLZ and CPZ in real human urine.

Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Drop with High Performance Liquid Chromatography for Determination of Decabrominated Diphenyl Ether in Surficial Sediments / 分析化学

A method for the determination of decabrominated diphenyl ether(decaBDE) in sediment samples at trace level using dispersive liquid-liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) and high performance liquid chromatography-ultraviolet detector (HPLC-UV) has developed.Based on the data of interactive orthogonal array design, the optimization experimental conditions were obtained with BP artificial neural network model: 1.00 mL methanol as dispersive solvent, 35.0 μL dodecanol as extractive solvent, 10.00% NaCl, pH 5, and extraction in 10 min.The extraction recovery (ER) was 62.22% at the extraction conditions.The proposed method exhibited a wide linear range(3.5-1400 ng/g) with R~2 =0.9921.The limit of detection (LOD) and the limit of quantification (LOQ) of this method were 2.3 pg/g(S/N =2) and 5.6 pg/g(S/N = 5), respectively.The recoveries of real samples at different spiking levels of decaBDE were 104.2%, 98.4% and 97.7%, respectively.Extraction, concentration and separation procedures for decaBDE from the sediment sample were carried out by one step, and hence, the process of DLLME-SFO for decaBDE was shortened.

Rapid Determination of Four Kinds of Furocoumarin Compounds in Traditional Chinese Medicine by Dispersive Liquid-Liquid Microextraction / 分析化学

A method was developed for the determination of furocoumarin compounds(psoralen, oxypeucedanin, imperatorin, isoimperatorin) in traditional Chinese medicine samples by dispersive liquid-liquid microextraction(DLLME) coupled with high performance liquid chromatography and the relation of sample solution volume, sediment phase volume with enrichment factors was deducted. Some important parameters that influenced the extraction efficiency were optimized: 50 μL carbon tetrachloride and 300 μL acetonitrile were rapidly injected into 1.5 mL sample solution containing 2.5%(w/V) NaCl. After centrifugation at 3500 r/min for 3 min, the sedimented CCl_4 phase was pumped and recorded the volume, then dissolved with methanol and injected into the HPLC for analysis. Under the optimum conditions, a good linear relationship was obtained in the range of 0.006 6.00 mg/L of both psoralen and oxypeucedanin and 0.006-12.0 mg/L of both imperatorin and isoimperatorin. The limits of detection were 1.0-3.0 μg/L(S/N=3). The relative standard deviations were 2.3%-5.4%(n=5). The enrichment factors ranged from 12.6 to 38.5 folds. The average recoveries ranged from 97.5% to 114.8%. The four kinds of furocoumarin compounds in Radix Angelicae dahuricae and Yuanhu Zhitong tablet were determined by the proposed method with satisfactory results.