Highly sensitive determination of tetrabromobisphenol A and bisphenol A in environmental water samples by solid‐phase extraction and liquid chromatography‐tandem mass spectrometry

Using bamboo‐activated charcoal as SPE adsorbent, a novel SPE method was developed for the sensitive determination of tetrabromobisphenol A and bisphenol A in environmental water samples by rapid‐resolution LC‐ESI‐MS/MS. Important parameters influencing extraction efficiency, including type of eluent, eluent volume, sample pH, volume and flow rate, were investigated and optimized. Under the optimal extraction conditions (eluent: 8 mL methanol, pH: 7; flow rate: 4 mL/min; sample volume: 100 mL), low LODs (0.01–0.02 ng/mL), good repeatability (6.2–8.3%) and wide linearity range (0.10–10 ng/mL) were obtained. Satisfied results were achieved when the proposed method was applied to determine the two target compounds in real‐world environmental water samples with spiked recoveries over the range of 80.5–119.8%. All these facts indicate that trace determination of tetrabromobisphenol A and bisphenol A in real‐world environmental water samples can be realized by bamboo‐activated charcoal SPE‐rapid resolution‐LC‐ESI‐MS/MS.     

Proconcentration of trace elements from high-purity thorium and uranium on Chelex-100 and determination by graphite furnace atomic absorption spectrometry with Zeeman-effect background correction

Preconcentration of trace impurities form large-sized samples of uranium metal and thorium oxide using a small column of Chelex-100 followed by their determination using graphite furnace atomic absorption spectrometry (GFAAS) is reported. A 0.5–10-g amount of the sample (uranium metal or thorium oxide) was dissolved, complexed with ammonium carbonate and subjected to the ion-exchange procedure. The retained analytes were eluted with 2–4 M nitric acid and brought to a small volume for a final dilution to 10-25 ml for their determination using GFAAS. The validity of the separation procedure and recoveries at μg kg⁻¹ levels was checked by standard addition; the recoveries were> 95%.     

基于整体柱的固相萃取-高效液相色谱法测定尿液中4种羟基多环芳烃

建立了基于聚合物整体柱的固相萃取-高效液相色谱测定尿液中4种羟基多环芳烃（OH-PAHs）的分析方法。在注射器管中合成聚（甲基丙烯酸丁酯-乙二醇二甲基丙烯酸酯）整体柱（poly （BMA-co-EDMA））,并将其用于尿液中4种羟基多环芳烃的前处理,同时考察了上样浓度、淋洗液、洗脱液和洗脱体积对萃取效率的影响。结合高效液相色谱-荧光分析,4种羟基多环芳烃在各自的范围内线性关系良好（r≥0.9991）;方法的检出限和定量限分别为0.06~0.09 ng/mL和0.20~0.30 ng/mL;日内（n=5）和日间（n=3）精密度分别为1.4%~5.3%和2.6%~7.3%。对焦炉工人尿液样品进行加标（3 ng/mL）回收试验,回收率为78.2%~117.0%。该固相萃取柱能够有效萃取和净化尿液中4种羟基多环芳烃,并且可以重复使用。该法简单、准确,可应用于尿液中羟基多环芳烃的分析。     

Hydride generation atomic absorption spectrometric determination of bismuth after separation and preconcentration with modified alumina

A simple and sensitive method has been developed for the trace determination of bismuth in aqueous samples by a combination of solid‐phase extraction and hydride generation atomic absorption spectrometry. The method is based on the use of a column packed with 2‐mercaptobenzothiazole immobilized on sodium dodecyl sulfate coated alumina. Different parameters influencing the separation and preconcentration of bismuth such as pH, sample volume, type, and concentration of eluent, and the flow rate of sample and eluent were studied. A sample volume of 500.0 mL resulted in a preconcentration factor of 100. The precision (relative standard deviation, N = 10) at the 300 ng/L level and the limit of detection (3s) were found to be 2.3% and 12 ng/L, respectively. The developed method was successfully applied to the determination of bismuth in natural water samples and two certified reference materials.     

Application of flow injection on-line electrothermal atomic absorption spectrometry to the determination of rhodium

A fully automated procedure for the determination of rhodium has been developed using flow injection (FI) on-line microcolumn preconcentration coupled with electrothermal atomic absorption spectrometry (ETAAS). The proposed FI manifold and its operation make possible the introduction of the total eluate volume into the graphite atomizer, avoiding the necessity for optimisation of subsampling the eluate. Rhodium is adsorbed on a microcolumn packed with 1,5-bis(di-2-pyridyl)methylene thiocarbohydrazide immobilized on silica gel (DPTH-gel). Under the optimum conditions, using a 60 s preconcentration time, a sample flow rate of 3.5 mL min(-1) and an injection volume of eluent of 50 microL, a linear calibration graph was obtained from 1 to at least 40 ng mL(-1) and the detection limit was 1 ng mL(-1). The proposed method has been successfully applied to the analysis of samples. Its performance was investigated against certified reference catalyst sample SRM-2557 and by recovery measurements on spiked samples (soil, foods and beverages).     

Preconcentration of copper with multi-walled carbon nanotubes pretreated by potassium permanganate cartridge for solid phase extraction prior to flame atomic absorption spectrometry

A procedure for the preconcentration of copper was described in this paper using multi-walled carbon nanotubes (MWCNTs) oxidized by potassium permanganate as the adsorbent for the enrichment of trace copper in water samples. Important parameters, such as the sample pH, the concentration and volume of eluent, sample flow rate and volume, and interference of coexisting ions, were investigated. The obtained results indicated that proposed method possessed an excellent analytical performance. The linear range, the detection limit, and precison (RSD) were 1-100 ng/mL (R2 = 0.9993), 0.32 ng/mL and 2.88%, respectively. The results showed that copper could be adsorbed quantitatively on the pretreated MWCNTs with potassium permanganate, and proposed method was very useful in the monitoring of copper in the environment.     

Liquid chromatography-tandem mass spectrometric assay for the nucleoside reverse transcriptase inhibitor emtricitabine in human plasma

A liquid chromatography-tandem mass spectrometric assay for the determination of the antiretroviral nucleoside emtricitabine in human plasma was developed and validated using a simple sample pre-treatment procedure. After addition of 5'-deoxy-5-fluorocytidine as the internal standard and protein precipitation with acetonitrile, the supernatant was directly injected in the isocratic chromatographic system using a polar embedded reversed-phase column and formic acid in water-methanol as the eluent. The eluate was completely led into an electrospray interface with positive ionization and the analytes were quantified using triple quadrupole mass spectrometry. The assay was validated in the range 5-5000 ng/mL. Intra-day precisions were 相似文献   

Validation and application of a method for the determination of nicotine and five major metabolites in smokers' urine by solid-phase extraction and liquid chromatography-tandem mass spectrometry

An SPE-LC-MS/MS method was developed, validated and applied to the determination of nicotine and five major metabolites in human urine: cotinine, trans-3'-hydroxycotinine, nicotine-N-glucuronide, cotinine-N-glucuronide and trans-3'-hydroxycotinine-O-glucuronide. A 500 microL urine sample was pH-adjusted with phosphate buffer (1.5 mL) containing nicotine-methyl-d3, cotinine-methyl-d3 and trans-3'-hydroxycotinine-methyl-d3 internal standards. For the unconjugated metabolites, an aliquot (800 microL) of the buffered solution was applied to a 30 mg Oasis HLB-SPE column, rinsed with 2% NH4OH/H2O (3.0 mL) and H2O (3.0 mL) and eluted with methanol (500 microL). The eluate was analyzed isocratically (100% methanol) by LC-MS/MS on a diol column (50 x 2.1 mm). For the total metabolites, a beta-glucuronidase/buffer preparation (100 microL) was added to the remaining buffered solution and incubated at 37 degrees C (20 h). An aliquot (800 microL) of the enzymatically treated buffered solution was extracted and analyzed in the same manner. The conjugated metabolites were determined indirectly by subtraction. The quantitation range of the method (ng/mL) was 14-10,320 for nicotine, 15-9800 for cotinine and 32-19,220 for trans-3'-hydroxycotinine. The validated method was used to observe diurnal variations from a smoker's spot urine samples, elimination half-lives from a smoker's 24 h urine samples and metabolite distribution profiles in the spot and 24 h urine samples.     

Solid phase extraction of trace amounts of Pb(II) in opium, heroin, lipstick, plants and water samples using modified magnetite nanoparticles prior to its atomic absorption determination

A new, simple, fast and reliable solid-phase extraction method has been developed for separation/preconcentration of trace amounts of Pb(II) using dithizone/sodium dodecyl sulfate-immobilized on alumina-coated magnetite nanoparticles, and its determination by flame atomic absorption spectrometry (FAAS) and graphite furnace atomic absorption spectrometry (GFAAS) after eluting with 4.0?mol?L^?1 HNO₃. Optimal experimental conditions including pH, sample volume, eluent concentration and volume, and co-existing ions have been studied and established. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range and relative standard deviation of Pb(II) using FAAS technique were 280 (for 560?mL of sample solution), 0.28?ng?mL^?1, 1.4?C70?ng?mL^?1 and 4.6% (for 10?ng?mL^?1, n?=?10), respectively. These analytical parameters using GFAAS technique were 300 (for 600?mL of sample solution), 0.002?ng?mL^?1, 0.006?C13.2?ng?mL^?1 and 3.1% (for 5?ng?mL^?1, n?=?10), respectively. The presented procedure was successfully applied for determination of Pb(II) content in opium, heroin, lipstick, plants and water samples.     

Determination of cadmium in river water by electrothermal atomic absorption spectrometry after internal standardization-assisted rapid coprecipitation with lanthanum phosphate.

Cadmium ranging from 1 - 8 ng could be coprecipitated quantitatively with lanthanum phosphate at pH 5 - 6 from up to 200 mL of river water samples spiked with 5 microg of indium as an internal standard. Cadmium and indium coprecipitated were measured by using electrothermal atomic absorption spectrometry. The cadmium content in the original sample solution could be determined by internal standardization with indium. Since complete collection of the precipitate and strict adjustment of the volume of the final solution after coprecipitation are not required in this method, the precipitate could be collected by using decantation and centrifugation, and then dissolved with 1 mL of about 2.4 mol L(-1) nitric acid. The proposed method is simple and rapid, and enrichment close to 200-times can be attained; the detection limit (3sigma, n = 6) was 0.63 ng L(-1) in 200 mL of the sample solution.     

聚[2-(丙烯酰氧基)乙基]三甲基氯化铵-乙二醇二甲基丙烯酸酯整体柱固相萃取结合高效液相色谱法测定尿液中3种苯二氮（卄卓）类药物

以[2-（丙烯酰氧基）乙基]三甲基氯化铵（DAC）为单体,乙二醇二甲基丙烯酸酯（EDMA）为交联剂在注射器中制备聚合物整体柱,用其固相萃取尿液中溴西泮（BRZ）、劳拉西泮（LRZ）和地西泮（DZP）3种苯二氮（卄卓）类药物（BZDs）,并采用高效液相色谱法（HPLC）分析。实验考察了整体柱聚合时间及固相萃取条件（淋洗溶液、洗脱溶剂种类和体积）对BZDs萃取效率的影响。结果表明,仅聚合4 h得到的整体柱对BZDs吸附效率为100%。取尿液样品4 mL上样,用4 mL H₂O冲洗,1 mL乙酸乙酯洗脱,采用高效液相色谱分析。在最优条件下,3种BZDs在4.0~1000 ng/mL范围内线性关系良好（r=0.999）,检出限（S/N=3）和定量限（S/N=10）分别为1.0~1.2 ng/mL和3.3~4.0 ng/mL;在10、25和50 ng/mL加标水平下回收率为81.4%~102%,日内（n=3）和日间（n=3）相对标准偏差分别为1.2%~4.5%和2.5%~8.3%。该整体柱可对尿液中3种BZDs有效净化,且富集达12~15倍。方法构筑的聚合物整体柱制备简单,萃取高效,可成功用于尿液中3种BZDs的分析。     

Development and validation of an LC-MS/MS method for profiling 39 urinary steroids (estrogens,androgens, corticoids,and progestins)

Abnormal production or metabolism of steroid hormones is responsible for the development of endocrine diseases. Thus, accurate quantification of steroid hormones is needed for both research into clinical conditions and diagnostic and monitoring purposes. An improved analytical method for profiling 39 steroids in urine using LC–MS/MS was developed. As a pre-treatment procedure prior to LC–tandem mass spectrometry (LC–MS/MS) analysis, hydrolysis using β-glucuronidase and solid-phase extraction for purifying the samples were performed. Steroids were separated using Waters ACQUITY BEH C₁₈ column (2.1 × 100 mm, 1.7 μm) and a mobile phase consisting of eluent A (0.01% formic acid and 1 mm ammonium formate in water) and eluent B (0.01% formic acid and 1 mm ammonium formate in methanol) with a gradient program at a flow rate of 0.4 mL/min. Under the optimized method, the linearity of calibration curves was higher than 0.992. The limits of detection at signal-to-noise ratio of 3 were 0.03–90 ng/mL. The developed novel LC–MS/MS method can quantitatively profile 39 steroids in a single analytical run. Steroid profiling based on quantitative results could improve the diagnosis and monitoring of hormone-dependent diseases.     

A simple and sensitive assay for the quantitative analysis of paclitaxel and metabolites in human plasma using liquid chromatography/tandem mass spectrometry

A sensitive and specific LC-MS/MS assay for the determination of paclitaxel and its 3'p- and 6-alpha-hydroxy metabolites is presented. A 200 microL plasma aliquot was spiked with a 13C6-labeled paclitaxel internal standard and extracted with 1.0 mL tert-butylmethylether. Dried extracts were reconstituted in 0.1 M ammonium acetate-acetonitrile (1:1, v/v) and 25 microL volumes were injected onto the HPLC system. Separation was performed on a 150 x 2.1 mm C18 column using an alkaline eluent (10 mm ammonium hydroxide-methanol, 30:70, v/v). Detection was performed by positive ion electrospray followed by tandem mass spectrometry. The assay quantifies a range for paclitaxel from 0.25 to 1000 ng/mL and metabolites from 0.25 to 100 ng/mL using 200 microL human plasma samples. Validation results demonstrate that paclitaxel and metabolite concentrations can be accurately and precisely quantified in human plasma. This assay is now used to support clinical pharmacologic studies with paclitaxel.     

Field preconcentration of cadmium from seawater by using a minicolumn packed with Amberlite XAD-4/4-(2-pyridylazo) resorcinol and its flow-injection-flame atomic absorption spectrometric determination at the ng L(-1) Level

A flow injection analysis-flame atomic absorption spectrometric method for the determination of cadmium in seawater was developed with the aim of yielding a sensitive assay with a low detection limit. The method employs a field flow preconcentration technique involving a minicolumn containing Amberlite XAD-4 impregnated with the complexing agent 4-(2-pyridylazo) resorcinol. A Plackett-Burman 2(7)x3/32 design for seven factors (sample pH, sample flow rate, eluent volume, eluent concentration, eluent flow rate, ethanol percentage in the eluent and minicolumn diameter) was carried out in order to find the significant variables affecting the field continuous preconcentration system (FCPS) and the flow injection elution manifold for cadmium determination in seawater samples by flame atomic absorption spectrometry. Cadmium can be preconcentrated with an enrichment factor of 1053 for a sample volume of 200 mL and a preconcentration time of 57 min. In these experimental conditions, the method provides a linear relationship between absorbance and cadmium concentration in the range from 22-1900 ng L(-1), with a detection limit (3SD) of 6 ng L(-1). The precision (expressed as relative standard deviation) for eleven independent determinations reached values of 8.9-0.8% in cadmium solutions of 50-700 ng L(-1). Analysis of certified reference materials (SLEW-3 and NASS-5) showed good agreement with the certified value. This procedure was applied to the determination of cadmium in seawater from Galicia (Spain).     

免疫亲和柱净化-超高效液相色谱-三重四极杆质谱法高灵敏测定尿液和血浆中3种鹅膏毒肽

建立了超高效液相色谱-三重四极杆质谱高灵敏测定尿液和血浆中α-鹅膏毒肽、β-鹅膏毒肽和γ-鹅膏毒肽的方法。经过免疫亲和柱净化,尿液样品浓缩20倍、血浆样品浓缩10倍,以Kinetex Biphenyl色谱柱(100 mm×2.1 mm, 1.7 μm)作为分析柱,甲醇-0.005%(v/v)甲酸水溶液作为流动相进行梯度洗脱分离,电喷雾电离、负离子、多反应监测模式下检测,外标法定量。3种鹅膏毒肽的线性范围为0.1~200 ng/mL,相关系数(r)>0.999。尿液和血浆中3种鹅膏毒肽的基质效应和提取回收率分别为92%~108%和90%~103%,变异系数均小于13%。尿液中3种鹅膏毒肽的准确度为-9.4%~8.0%,重复性和中间精度分别为3.0%~14%和3.5%~18%,当取样量为2.00 mL时,方法的检出限均为0.002 ng/mL;血浆中3种鹅膏毒肽的准确度为-13%~8.0%,重复性和中间精度分别为3.9%~9.7%和5.5%~12%,当取样量为1.00 mL时,方法的检出限均为0.004 ng/mL。该法操作简单、灵敏、准确,已在中毒患者摄入野生蘑菇后138 h的尿液中检出0.0067 ng/mL α-鹅膏毒肽和0.0059 ng/mL β-鹅膏毒肽。该法已成功解决中毒患者尿液和血浆中超痕量鹅膏毒肽的检测难题,对于疑似中毒病人的早诊断、早治疗、降低死亡率都具有非常重要意义,也为今后开展此类毒素毒理作用及机体代谢规律的研究提供了可靠的技术支撑。     

Development and evaluation of an enzyme-linked immunosorbent assay (ELISA) method for the measurement of 2,4-dichlorophenoxyacetic acid in human urine

An enzyme-linked immunosorbent assay (ELISA) method was developed to quantitatively measure 2,4-dichlorophenoxyacetic acid (2,4-D) in human urine. Samples were diluted (1:5) with phosphate-buffered saline containing 0.05% Tween and 0.02% sodium azide, with analysis by a 96-microwell plate immunoassay format. No clean up was required as dilution step minimized sample interferences. Fifty urine samples were received without identifiers from a subset of pesticide applicators and their spouses in an EPA pesticide exposure study (PES) and analyzed by the ELISA method and a conventional gas chromatography/mass spectrometry (GC/MS) procedure. For the GC/MS analysis, urine samples were extracted with acidic dichloromethane (DCM); methylated by diazomethane and fractionated by a Florisil solid phase extraction (SPE) column prior to GC/MS detection. The percent relative standard deviation (%R.S.D.) of the 96-microwell plate triplicate assays ranged from 1.2 to 22% for the urine samples. Day-to-day variation of the assay results was within ±20%. Quantitative recoveries (>70%) of 2,4-D were obtained for the spiked urine samples by the ELISA method. Quantitative recoveries (>80%) of 2,4-D were also obtained for these samples by the GC/MS procedure. The overall method precision of these samples was within ±20% for both the ELISA and GC/MS methods. The estimated quantification limit for 2,4-D in urine was 30 ng/mL by ELISA and 0.2 ng/mL by GC/MS. A higher quantification limit for the ELISA method is partly due to the requirement of a 1:5 dilution to remove the urine sample matrix effect. The GC/MS method can accommodate a 10:1 concentration factor (10 mL of urine converted into 1 mL organic solvent for analysis) but requires extraction, methylation and clean up on a solid phase column. The immunoassay and GC/MS data were highly correlated, with a correlation coefficient of 0.94 and a slope of 1.00. Favorable results between the two methods were achieved despite the vast differences in sample preparation. Results indicated that the ELISA method could be used as a high throughput, quantitative monitoring tool for human urine samples to identify individuals with exposure to 2,4-D above the typical background levels.     

Sorbent separation and enrichment method for cobalt ions determination by graphite furnace atomic absorption spectrometry in water and urine samples using multiwall carbon nanotubes

A new cobalt ions pre-concentration method, optimised by fractional factorial design, using multiwall carbon nanotubes (MWCNTs) with further Graphite Furnace Atomic Absorption Spectrometry (GFAAS) quantification is described. The method explores the high chemical and physical stability of MWCNTs for improving the detectability of GFAAS. It is based on off-line pre-concentration of 20.0 mL of sample previously buffered (pH 8.82) on MWCNTs at a flow rate of 10.0 mL min^?1. After the pre-concentration procedure, the elution step was carried out with 500 µL of 0.524 mol L^?1 HNO₃ solution at a flow rate of 2.0 mL min^?1. Fractional factorial designs and response surface methodology were employed for optimisation of all chemical parameters involved in the pre-concentration procedure, including pre-concentration flow rate, buffer and eluent concentration, sample pH and elution volume. The method provides a linear calibration range from 0.03 up to 7.00 µg L^?1 with linear correlation coefficient higher than 0.9994 and limits of detection and quantification of 0.01 and 0.03 µg L^?1, respectively. Repeatability of the six measurements was found to be 2.38 and 1.84% for 0.3 and 4.5 µg L^?1 cobalt concentration, respectively. By pre-concentrating 20.0 mL of sample, a pre-concentration factor (PF) of 19.10-fold and a consumption index of 1.05 mL were obtained. The pre-concentration efficiency (PE) was found to be 9.55 min^?1. The proposed method was successfully applied for the pre-concentration and determination of cobalt in water and urine samples with satisfactory recovery values.     

Determination of digoxin and its metabolites in biological samples by solidphase supported liquid-liquid extraction-liquid chromatography-tandem mass spectrometryEI北大核心CSCD

采用固相支撑液液萃取-超高效液相色谱-串联质谱（SLE-UPLC-MS/MS）技术建立了生物样本血液、尿液和肝组织中地高辛（DG）及其3种代谢物的分析方法。生物样本经匀浆、蛋白沉淀后,通过含有硅藻土的固相支撑液液萃取（SLE）柱净化富集,经洗脱、定容后进行LC-MS/MS分析。结果表明,血液基质中,地高辛在0.1～100 ng/mL浓度范围内线性关系良好;肝脏和尿液基质中,地高辛在0.2～100 ng/mL浓度范围内线性关系良好,地高辛的3种代谢物在0.5～100 ng/mL浓度范围内线性关系良好,3个浓度水平（10, 50和100 ng/mL）的加标回收率为60.5%～95.6%,基质效应80.7%～113.6%,日内、日间相对标准偏差（RSD）均小于13%,检出限为0.1～0.5 ng/mL。所建立的方法可用于生物样本中地高辛及其代谢物的定性定量分析。     

Determination of ephedra alkaloids in urine and plasma by HPLC-UV: collaborative study

Ten collaborating laboratories determined the ephedra alkaloid content (ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, methylephedrine, and methylpseudoephedrine) in 8 blind duplicates of human plasma and urine using high-performance liquid chromatography (HPLC) with UV detection. In addition to negative urine and plasma controls, urine samples were spiked with individual ephedra alkaloids ranging in concentration from about 1 to 5 microg/mL. Plasma samples were spiked with individual ephedra alkaloids ranging in concentration from about 100 to 400 ng/mL. Sample solutions were treated to solid-phase extraction using a strong-cation exchange column to help remove interferences. The HPLC analyses were performed on a polar-embedded phenyl column using UV detection at 210 nm. The ephedra alkaloids were not consistently detected in any of the spiked plasma samples. When ephedra alkaloids were detected in the plasma samples, reproducibility between blind replicate samples was very poor. Repeatability, reproducibility, and accuracy were also very poor for the spiked urine samples. On the basis of these results, the HPLC-UV method for the determination of ephedra alkaloids in human urine and plasma is not recommended for adoption as Official First Action.     

高效液相色谱-串联质谱法测定加工肉制品中莱克多巴胺及克伦特罗的含量

建立了高效液相色谱串联质谱测定加工肉制品中莱克多巴胺和克伦特罗的方法。采用阳离子交换色谱柱(SCX)分离目标化合物,改进了前处理方法,采用PXC固相萃取柱净化,并对洗脱溶液和高效液相色谱串联质谱的各参数进行优化。高效液相色谱流动相流速为0.4 mL/min,进样量为10μL,柱温为40℃。样品均质后加入30μLβ-盐酸葡萄糖醛苷酶-芳基硫酸酯酶,并经0.02 mol/L乙酸铵溶液(pH 5.2)提取,离心,过固相萃取柱净化。两种目标化合物在0.1～100μg/L范围内线性关系良好,检出限和定量下限分别不超过0.04μg/kg和0.15μg/kg。样品平均加标回收率为72%～98%,RSD低于8.5%。结果表明,此方法适于加工肉制品中莱克多巴胺和克伦特罗的测定。