Combining microwave-assisted extraction and liquid chromatography–ion-trap mass spectrometry for the analysis of hexabromocyclododecane diastereoisomers in marine sediments

An efficient microwave-assisted extraction (MAE) procedure coupled with high performance liquid chromatography–electrospray-ion-trap mass spectrometry (HPLC–ESI-ITMS) has been evaluated to determine hexabromocyclododecane diastereoisomers (α-, β- and γ-HBCD) in marine sediments. The composition of the LC mobile phase (consisting of water, methanol and acetonitrile) and the parameters of electrospray ionization (ESI) were evaluated to obtain chromatographic baseline separation and high sensitivity for the detection of these diastereoisomers. The effects of various operating parameters on the quantitative extraction of the HBCDs through MAE were systematically investigated. The three diastereoisomers were then quantitated by HPLC–ITMS employing ESI operated in the negative ionization mode. The HBCDs were extracted from the sediments through MAE using 40 mL of acetone/n-hexane (1/3, v/v) at 90 °C for 12 min. The limits of quantitation (LOQ) ranged from 25 to 40 pg/g (dry weight) in 5 g of the sediment samples. The recoveries of the HBCDs in spiked sediment samples ranged from 68 to 91% (relative standard derivation: 2–11%). The extraction efficiency of the MAE technique was also compared with Soxhlet extraction and pressurized liquid extraction.     

水中痕量苯酚的微波萃取气相色谱分析

A method of microwave-assisted extraction and gas chromatography for determination of trace phenol in water was established.The conditions of microwave extraction and derivation were optimized.Acetone-cyclohexane(1∶1) mixture was used as extracting agent for water sample containing phenol and acetic anhydride was employed for the direct acetylation of phenol.Petroleum ether was used as the extracting agent to extract the derivative of phenol.Detection was carried out in GC-FID equipped with DB-17(30 m×0.53 ...     

Evaluation of various QuEChERS based methods for the analysis of herbicides and other commonly used pesticides in polished rice by LC-MS/MS

Four different extraction and clean-up protocols based on the QuEChERS method were compared for the development of an optimized sample preparation procedure for the multiresidue analysis of 16 commonly applied herbicides in rice crops using LC-QqQ/MS. Additionally the methods were evaluated for the analysis of 26 insecticides and fungicides currently used in rice crops. The methods comprise, in general, the hydratation of the sample with water followed by the extraction with acetonitrile, phase separation with the addition of different salts and finally a clean-up step with various sorbents.Matrix effects were evaluated for the 4 studied methods using LC-QqQ/MS. Additionally LC-TOF/MS was used to compare the co-extractants obtained with the four assayed methodologies. Thirty-six pesticides presented good performance with recoveries in the range 70-120% and relative standard deviations below 20% using 7.5 g of milled polished rice and the buffered acetate QuEChERS method without clean-up at both fortification levels: 10 and 300 μg kg⁻¹. The other six pesticides presented low recovery rates, nevertheless all these analytes could be analyzed with at least one of the other three studied procedures.     

微波辅助萃取气相色谱-质谱联用测定蔬菜中的扑草净

研究了微波辅助萃取气相色谱．质谱联用测定植物样品中扑草净的方法，比较了几种不同溶剂的微波萃取效率，从而选取二氯甲烷为萃取溶剂，并采用三因素三水平的正交设计试验对溶剂体积、微波辐射时间、微波功率进行了优化。在优化的实验条件下分析了合成菠菜样品，对0．2μg/g和0．02μg/g的合成菠菜样品，回收率分别为99．5％和92．5％，相对标准偏差分别为5．0％和ll％，方法的线性范围为1．0—400ng／g，检出限为0．22ng／g。方法适合于分析植物样品中的扑草净。     

微波辅助萃取-气相色谱质谱法检测生物体内的多溴联苯醚

建立了微波辅助萃取-气相色谱质谱法测定生物样品中的多溴联苯醚(PBDEs)的方法,优化了萃取剂的种类、萃取剂用量、萃取时间等微波萃取条件和GC-MS仪器分析条件。正己烷-丙酮混合溶剂提取后,经实验室自制的多层硅胶柱分离纯化,用气相色谱-质谱进行测定,该方法基质加标回收率在60%～77%之间,相对标准偏差在11%～18%之间,方法的检测限为0.03～0.20ng/g,适用于生物样品中PBDEs的测定。     

Simultaneous determination of fluoroquinolone and tetracycline antibacterials in sewage sludge using ultrasonic-assisted extraction and HPLC-MS/MS

A reliable method was proposed for the simultaneous determination of five fluoroquinolones (FQs) and two tetracyclines (TCs) in sewage sludge using ultrasonic-assisted extraction (USE) followed by SPE cleanup and high-performance liquid chromatography-mass spectrometry (HPLC-MS)/MS analysis with electrospray ionisation (ESI) in a positive mode. The USE conditions (e.g. extraction solvent, pH, and extraction cycles) and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) parameters were optimised. Quantification was performed by internal standard calibration in multiple reaction monitoring mode. Recoveries of the antibacterials ranged from 41 to 123%, with relative standard deviations within 17%. The sample-based limits of quantification were 10–63?ng?g^?1 dry weight (dw) for FQs (ciprofloxacin, enrofloxacin, lomefloxacin, norfloxacin, and ofloxacin) and 250–500?ng?g^?1 dw for TCs (tetracycline and oxytetracycline). The method was applied to determine the antibacterials in sewage sludge and sediment samples were collected from the Pearl River Delta, China. Ciprofloxacin, norfloxacin, and ofloxacin were frequently detected, ranging from 1052 to 17740?ng?g^?1 dw in dewatered sludge samples, 585–3545?ng?g^?1 dw in untreated solids, and 98–258?ng?g^?1 dw in an urban stream sediment sample, respectively. Lomefloxacin and enrofloxacin were also occasionally detected.     

Determination of senkirkine and senecionine in Tussilago farfara using microwave-assisted extraction and pressurized hot water extraction with liquid chromatography tandem mass spectrometry

Tussilago farfara (Kuan Donghua) is an important Chinese herbal medicine which has been shown to contain many bioactive compounds and widely used to relieve cough and resolve phlegm. However, besides therapeutic bioactive compounds, this herb has been found to contain toxic pyrrolizidine alkaloids (PAs), mainly senkirkine and traces of senecionine. In this report, conditions for microwave-assisted extraction (MAE) and pressurized hot water extraction (PHWE) were optimized for the extraction of the PAs. The results were compared against heating under reflux. It was found that the binary mixture of MeOH:H₂O (1:1) acidified using HCl to pH 2-3 was the optimal solvent for the extraction of the PAs in the plant materials. Liquid chromatography (LC) with ultra-violet (UV) detection and electrospray ionization mass spectrometry (ESI-MS) in the positive mode was used for the determination and quantitation of senkirkine and senecionine in the botanical extract. The proposed extraction methods with LC/MS allow for the rapid detection of the major and the minor alkaloids in T. farfara in the presence of co-eluting peaks. With LC/MS, the quantitative analysis of PAs in the extract was done using internal standard calibration and the precision was found to vary from 0.6% to 5.4% on different days. The limits of detection (LODs) and limits of quantitation (LOQs) for MAE and PHWE were found to vary from 0.26 μg/g to 1.04 μg/g and 1.32 μg/g to 5.29 μg/g, respectively. The method precision of MAE and PHWE were found to vary from 3.7% to 10.4% on different days. The results showed that major and minor alkaloids extracted using MAE and PHWE were comparable to that by heating under reflux. Our data also showed that significant ion suppression was not observed in the analysis of senkirkine and senecionine in the botanical extracts with co-eluting peaks.     

防晒类化妆品中2种帕地马酯的高效液相色谱检测及质谱确证

建立了同时测定防晒类化妆品中帕地马酯A和帕地马酯O的高效液相色谱分析方法及质谱确证方法。化妆品样品以甲醇为提取溶剂进行超声提取,提取液离心处理,取上清液经微孔滤膜过滤后测定。采用XTerra MS C18柱(250×4.6mm,5μm)分离,外标法定量。结果表明防晒类化妆品中帕地马酯A和帕地马酯O的方法定量限均为0.5mg/kg,在低、中、高3个添加水平范围内平均回收率为89.1%~112.5%,相对标准偏差为2.0%~7.7%。对于疑似阳性样品,进一步采用液相色谱-串联质谱法进行确证分析。该方法准确、快速、灵敏度高,适用于防晒类化妆品的实际检验工作。     

Robust microwave-assisted extraction protocol for determination of total mercury and methylmercury in fish tissues

A rapid and efficient closed vessel microwave-assisted extraction (MAE) method based on acidic leaching was developed and optimized for the extraction of total mercury (Hg), inorganic mercury (Hg²⁺) and methylmercury (CH₃Hg⁺) from fish tissues. The quantitative extraction of total Hg and mercury species from biological samples was achieved by using 5 mol L⁻¹ HCl and 0.25 mol L⁻¹ NaCl during 10 min at 60 °C. Total Hg content was determined using inductively coupled plasma mass spectrometry (ICP-MS). Mercury species were measured by liquid chromatography hyphenated with inductively coupled plasma mass spectrometry (LC-ICP-MS). The method was validated using biological certified reference materials ERM-CE464, DOLT-3, and NIST SRM-1946. The analytical results were in good agreement with the certified reference values of total Hg and CH₃Hg⁺ at a 95% confidence level. Further, accuracy validation using speciated isotope-dilution mass spectrometry (SIDMS, as described in the EPA Method 6800) was carried out. SIDMS was also applied to study and correct for unwanted species transformation reactions during and/or after sample preparation steps. For the studied reference materials, no statistically significant transformation between mercury species was observed during the extraction and determination procedures. The proposed method was successfully applied to fish tissues with good agreement between SIDMS results and external calibration (EC) results. Interspecies transformations in fish tissues were slightly higher than certified reference materials due to differences in matrix composition. Depending on the type of fish tissue, up to 10.24% of Hg²⁺ was methylated and up to 1.75% of CH₃Hg⁺ was demethylated to Hg²⁺.     

微波辅助萃取法测定烟草中有机氯类农药残留量

建立了一种微波辅助萃取-固相萃取净化测定烟草中17种有机氯类农药残留量的新方法. 样品用V(正己烷):V(乙酸乙酯)＝1:1提取, 提取液经Florisil固相萃取柱净化后, 采用气相色谱-电子捕获检测器(GC-μECD)进行检测. 17种有机氯农药的0.01、 0.05 mg/kg和0.5 mg/kg加标回收率均在82%以上, RSD在0.11%～8.2%之间, 能满足当前烟草中有机氯农药残留的检测要求.     

Development and optimisation of a single extraction procedure for the LC/MS/MS analysis of two pharmaceutical classes residues in sewage treatment plant

A unique extraction procedure leading to the separation of 2 different pharmaceutical classes molecules has been developed and optimised by chemometric tools. From only one sampling, this analytical method allows the determination of 21 pharmaceuticals from corticosteroids and β-blockers classes. Performing the SPE on Oasis MCX (mixed-mode cation exchange), the sequential elution of each pharmaceutical class is achievable, allowing a high purity level of extracts as well as high recovery rates. Performing a unique sample preparation results in an important save of time. The extracts were then analysed by LC/MS/MS, using a Hibar Purospher Star column for β-blockers and an X-Bridge column for corticosteroids with formate buffer (pH 3.8)/AcN and water/AcN mobile phases, respectively. This work also includes a study of the chromatographic and mass spectrometric parameters in order to increase the analyte signal. The optimised SPE-LC/MS/MS method was then applied to environmental samples from sewage treatment plant (STP). β-Blockers and corticosteroids were detected, respectively, in concentrations up to 318 ng L⁻¹ (sotalol) and 174 ng L⁻¹ (cortisone), in STP influents. Moreover, both pharmaceutical classes have also been detected in STP effluents. As far as we know, this is the first paper reporting the detection of corticosteroids in environmental waters. The developed analytical method can be used in further studies to investigate the environmental contamination by these drugs.     

QuEChERS-液相色谱串联质谱法快速检测果蔬中的农药多残留

建立了果蔬样品中氨基甲酸酯类、有机磷类、苯并咪唑类、苯甲酰脲类等各类29种农药多残留的液相色谱-串联质谱检测方法。采用QuEChERS方法进行前处理,样品经1%冰醋酸乙腈提取、醋酸钠和无水硫酸镁盐析后,上清液加入伯仲胺粉、C18粉及石墨化碳黑粉进行分散固相萃取净化。提取液经Waters SunFire C18(5μm,4.6×150 mm)色谱柱分离后,进行LC-MS/MS多反应监测模式下的定性及定量分析。29种农药的检出限在0.005~0.352μg/kg之间,定量限在0.015~1.176μg/kg之间。在1~10μg/kg的3个添加水平范围上,平均回收率在70%~119%之间,RSD小于16%。本方法可用于果蔬样品中农药多残留的确证检测。     

Semiquantitative determination of residues of amphetamine in sewage sludge samples

A procedure based on HPLC and mass spectrometric detection has been developed for screening of residues of the illicit drug amphetamine in sewage sludge. Sample pretreatment consisted in extraction by 50 mM formic acid and methanol (80:20 v/v), followed by adjustment of the pH to 10 and preconcentration by SPE at poly(di-vinylbenzene)-N-vinylpyrrolidone. HPLC separation of the extract was done on a C18 RP with a mixture of 50 mM formic acid and methanol (80:20 v/v) as mobile phase. The mass spectrometer was operated in the MS2 and MS3 mode using the transition from m/z 136 to 119 and from m/z 119 to 91. Due to the complex matrix, ionization suppression effects as well as shifts in the sensitivity of the detector within a series of runs could not be fully excluded. Therefore, quantitation was done by standard addition together with external standards, so that semiquantitative results could be obtained down to concentrations of 2 microg/kg sewage sludge. Samples taken from various municipal sewage treatment plants indicate that amphetamine residues are ubiquitous in urban areas.     

Determination of the oil content of seeds by focused microwave-assisted soxhlet extraction

Sumamry Soybean, rape and sunflower lipids have been extracted with a focused microwave-assisted Saxhlet extractor. The main factors affecting extraction efficiency, namely microwave irradiation power, number of cycles and microwave irradiation time were optimised by means of a power, number of cycles and microwave irradiation time were optimised by means of a central composite design based on a two-level-three-factor factorial design. A study of the influence of particle size on the extraction procedure was also performed. The results obtained were compared with those obtained by use of an ISO method using a conventional Soxhlet extractor. Quantitative results for lipid content based on gravimetric determinations and qualitative results based on analysis of fatty acid methyl esters and polymeric compounds were similar to those obtained by Soxhlet extraction with hexane. Substantial reduction of sample manipulation. analysis time and solvent wastage is achieved by use of the proposed method.     

Alkaline extraction in combination with microwave-assisted extraction followed by solid-phase extraction treatment for polycyclic aromatic hydrocarbons in a sediment sample

Microwave-assisted extraction using 1 M KOH/methanol (alkaline-MAE) in combination with solid-phase extraction treatment was developed and applied to polycyclic aromatic hydrocarbons (PAHs) in a sediment sample. Although various conditions were examined (100 or 150 °C for 10 or 30 min), comparable concentrations of PAHs to those obtained by conventional extraction with 1 M KOH/methanol at 70 °C for 4 h were obtained, even at 100 °C for 10 min. The concentrations obtained by using MeOH at 150 °C for 30 min without KOH were lower (by 1.3-37%) than those obtained by alkaline-MAE at 150 °C for 30 min. Since the developed technique can introduce higher concentration of benzo[ghi]perylene relative to those using pressurized liquid extraction (toluene, 150 °C, 15 MPa, 10 min, two cycles), the developed alkaline-MAE is a effective technique.     

Determination of hexabromocyclododecane isomers in sewage sludge by LC‐MS/MS

A method has been developed to determine α, β and γ diastereoisomers of hexabromocyclododecane (HBCD), a brominated flame retardant, in sewage sludge, based on the ultrasonic‐assisted extraction (UAE) of samples with dichloromethane–ACN (1:1) and the subsequent clean‐up of extracts by dispersive solid phase extraction with primary–secondary amine. Levels of HBCD diastereoisomers were determined by LC coupled with ESI MS/MS. Evaluation of the matrix effect showed a high ion suppression for all the diastereoisomers studied, which was counteracted by using a mixture of labelled HBCD diastereoisomers as internal standards. This method yielded recoveries in the range of 79.6–112.5% with SDs equal or lower than 9.1 The limits of detection were 0.3 ng/g for α‐ and β‐HBCD and 0.2 ng/g for γ‐HBCD. The developed method was successfully applied to 19 sludge samples collected from the province of Madrid (Spain). In most of the samples, β‐HBCD was below the method detection limit, whereas α‐ and γ‐HBCD were quantified in all of the sludge samples, and γ‐HBCD was the predominant diastereoisomer in 63% of the analyzed samples and α‐HBCD predominated in the rest.     

全自动在线涡流固相萃取-液相色谱-串联质谱法直接分析血清中4种雄激素

建立了一种全自动在线涡流固相萃取-液相色谱-质谱联用直接分析血清中4种雄激素的分析方法。50μL血清样品经高速离心后,可直接用涡流固相萃取柱在线富集和分析。 Turboflow C18-P在线固相萃取柱可有效去除血清基质。最佳上样流速和洗脱时间分别为4.0 mL/min和1.0 min。方法的线性范围在1.0~100.0μg/L之间,4种雄激素的检出限在0.2~0.3μg/L之间,相对标准偏差为2.9％~14.1％(n=5)。应用本方法对实际血清样品进行了分析,整个分析过程包括提取、分离、检测以及柱子再生在32 min内即可完成。     

微波辅助溶剂提取法对土壤中残留苯并咪唑类农药的测定

报道了微波辅助溶剂提取、液 液分配净化、反相液相色谱 荧光法测定土壤中苯并咪唑类农药多菌灵、噻菌灵残留量的方法。对微波辅助溶剂提取的功率、时间、提取溶剂等操作条件进行了研究。以2mol LNH4Cl溶液、乙醇为提取液,在240W微波功率,提取时间1min的优化操作条件下,方法的回收率为89%～99%,相对标准偏差为3%～10%,方法的最低检出质量浓度多菌灵为3 63×10-4mg L,噻菌灵为5.20×10-5mg L,最小检出量多菌灵为1.21×10-11g,噻菌灵为1.74×10-12g。     

茶叶中三氯杀螨醇残留量的微波萃取-固相微萃取-气相色谱快速检测方法

建立了微波辅助萃取-固相微萃取-气相色谱/电子捕获检测法快速测定茶叶中三氯杀螨醇的方法。采用自制的PDMS萃取头,优化了萃取溶剂的种类,微波辐射时间和微波功率等微波辅助萃取条件;研究了SPME萃取时间、搅拌速度、离子强度、解吸温度和解吸时间对萃取效率的影响。方法对三氯杀螨醇的检出限为0.048 ng/mL,线性范围为0.2~200 ng/mL。在优化的实验条件下,对乌龙茶进行添加回收试验,平均回收率为61.3%~72.8%,相对标准偏差为8.0%~16.3%。本方法适合于茶叶中痕量三氯杀螨醇快速检测。     

Analyses of benzodiazepines and their metabolites in various biological matrices by LC-MS(/MS)

Benzodiazepines are among the most frequently prescribed drugs due to their sedative, hypnotic, anxiolytic, muscle relaxant and antiepileptic properties. Because of the high consumption of benzodiazepines worldwide, this class of drugs and their metabolites are frequently present in both clinical and forensic cases. For these reasons, the analysis of benzodiazepines and their metabolites in biological fluids is of great interest to clinicians and forensic toxicologists. This paper reviews procedures for multi-analyte single-stage (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) using different mass analyzers for the screening, identification and/or quantification of drugs, poisons and/or their metabolites in blood, plasma, serum or urine published since 2001. Basic information about the biosamples assayed, work-up, LC column, mobile phase, ionization type, mass spectral detection mode, matrix effects and validation data for each procedure is summarized. The feasibility of using LC-MS(/MS) techniques to identify and quantify benzodiazepines and their metabolites is also discussed.