Solid phase analytical derivatization of anthropogenic and natural phenolic estrogen mimics with pentafluoropyridine for gas chromatography-mass spectrometry

A simple, low cost, fast and sensitive method is reported for the determination of the four endocrine disrupting chemicals (EDCs) 4-tert-butylphenol, 4-tert-octylphenol, bisphenol A and 17β-estradiol using pentafluoropyridine as the derivatizing reagent. These EDCs were determined by simultaneous extraction and derivatization in a solid phase analytical derivatization (SPAD) technique without the aid of any phase transfer catalyst (PTC) or an ion-pair mechanism. Recoveries of analytes as their tetrafluoropyridyl derivatives from water ranged from 71% for 4-tert-butylphenol to 106% for 17β-estradiol; from urine they ranged from 61% for 17β-estradiol to 91% for 4-tert-octylphenol; and from humic acids solution the ranged from 59% for 17β-estradiol to 104% for 4-tert-octylphenol in humic acid solutions. Calibration curves were constructed from a matrix of human male urine in the range 1-40 ng/mL and had coefficients of correlation greater than 0.99. For 4-tert-butylphenol, bisphenol A and 17β-estradiol the limits of quantitation were 5 ng/mL and for 4-tert-octylphenol it was 1 ng/mL. This method was applied to determine EDCs and detected 4-tert-octylphenol, bisphenol A and 17β-estradiol in concentrations comparable to those found in the literature. The method offers advantages in speed of analysis, reduced reagent and specificity of derivatization.     

Coulometric titration of some phenolic steroids with bromine based on thin-layer hydrodynamic biamperometric end-point detection

Four phenolic steroids were titrated coulometrically with bromine in a methanol—water solvent containing hydrochloric acid and sodium bromide. End-point detection was achieved with a twin electrode thin-layer cell placed in a flow loop connected to the titration vessel. Linear-segmented biamperometric titration curves were recorded. Concentrations of 17-β-estradiol were determined in the range from 442 ppb to 8.84 ppm with relative inaccuracies of -1.3% and +2.2%, respectively. Part-per-million solutions of estrone and estriol were titrated with good accuracy and precision. Somewhat poorer precision and accuracy was found for the determination of 17-α-ethynyl estradiol.     

固相萃取-超高效液相色谱-三重四极杆质谱法同时测定不同水体中的6种雌激素

建立了固相萃取-超高效液相色谱-三重四极杆质谱（SPE-UPLC-MS/MS）联用技术同时测定不同水体中6种雌激素（雌三醇、17-β-雌二醇、17- α-雌二醇、雌酮、炔雌醇、己烯雌酚）的分析方法。样品经HLB固相萃取柱提取和净化后经BEH C18色谱柱分离,采用MS/MS多反应监测模式（MRM）进行分析。采用内标法定量,以雌三醇-D3、17-β-雌二醇-D2、己烯雌酚-D8为内标。当6种雌激素的质量浓度在1.0~100 μg/L线性范围内时,所得回归方程的相关系数（r）均不小于0.9982;方法检出限为0.27~0.45 ng/L,定量限为1.08~1.78 ng/L;在高、中、低3个添加水平下的回收率为68.3%~97.4%,相对标准偏差（RSD）小于15%。该方法灵敏、准确,检测范围广,分析速度快,适用于地表水、废水、饮用水源水及生活用水等不同水体中6种雌激素的同时检测。     

Determination of glutathione disulfide levels in biological samples using thiol-disulfide exchanging agent, dithiothreitol

A reverse-phase HPLC method incorporating dithiothreitol (DTT) reduction for quantitative determination of oxidized glutathione (GSSG) in biological samples is described here. This method is based on our previous enzymatic reduction technique that uses N-1-(pyrenyl) maleimide (NPM) as a derivatizing agent. In our earlier method, glutathione disulfide (GSSG) was measured by first reducing it to GSH with glutathione reductase (GR) in the presence of NADPH. However, this is a very costly and time-consuming technique. The method described here employs a common and inexpensive thiol-disulfide exchanging agent, DTT, for reduction of GSSG to GSH, followed by derivatization with NPM. The calibration curves are linear over a concentration range of 25-1250 nm (r(2) > 0.995). The coefficients of variations for intra-run precision and inter-run precision range from 0.49 to 5.10% with an accuracy range of 1.78-6.15%. The percentage of relative recovery ranges from 97.3 to 103.2%. This new method provides a simple, efficient, and cost-effective way of determining glutathione disulfide levels with a 2.5 nm limit of detection per 5 microL injection volume.     

Multifactorial optimization approach for the determination of polycyclic aromatic hydrocarbons in river sediments by gas chromatography-quadrupole ion trap selected ion storage mass spectrometry

A procedure for the determination of very low polycyclic aromatic hydrocarbons (PAHs) concentrations in sediment samples has been developed by gas chromatography-quadrupole ion trap mass spectrometry (GC-QIT MS) after extraction with dichloromethane and purification by using silica gel cleanup. Identification and quantification of analytes were based on the selected ion storage (SIS) strategy using deuterated PAHs as internal standards. In order to search out the main factors affecting the SIS mass spectrometry efficiency, four MS parameters, including target total ion count (TTIC), waveform amplitude (WA), transfer line (XLT) and ion trap temperatures (ITT) were subjected to a complete multifactorial design. The most relevant parameters obtained (TTIC and WA) were optimized by a rotatable and orthogonal composite design. Optimum values for these parameters were selected for the development of the method involving PAH determination in sediment samples. The optimized method exhibited a range of 111-760% higher signal-to-noise (S/N) ratios for PAHs in comparison with the method operated by the default conditions, demonstrating that the multifactorial optimization contributed to substantially improve the sensitivity of the GC-QIT MS determination. The accuracy of the method was verified by analyzing NWRI EC-3 certified reference material (Lake Ontario sediment). The selectivity, sensitivity (limits of quantification were in the range of 0.02-11.0 ng g(-1)), accuracy (recoveries >or=77%) and precision (RSD相似文献   

Solid-phase extraction using molecularly imprinted polymer for selective extraction of natural and synthetic estrogens from aqueous samples

A method is proposed for the clean-up and preconcentration of natural and synthetic estrogens from aqueous samples employing molecularly imprinted polymer (MIP) as selective sorbent for solid-phase extraction (SPE). The selectivity of the MIP was checked toward several selected natural and synthetic estrogens such as estrone (E1), 17β-estradiol (β-E2), 17α-estradiol (α-E2), estriol (E3), 17α-ethinylestradiol (EE2), dienestrol (DIES) and diethylstilbestrol (DES). Ultrahigh pressure liquid chromatography (UHPLC) coupled to a TSQ triple quadrupole mass spectrometry (QqQ) was used for analysis of target analytes. The chromatographic separation of the selected compounds was performed in less than 2 min under isocratic conditions. The method was applied to the analysis of estrogens in spiked river and tap water samples. High recoveries (>82%) for estrone, 17β-estradiol, 17α-estradiol, estriol and 17α-ethinylestradiol were obtained. Lower but still satisfactory recoveries (>48%) were achieved for dienestrol and diethylstilbestrol. The method was validated and found to be linear in the range 50-500 ng L(-1) with correlation coefficients (R(2)) greater than 0.995 and repeatability relative standard deviation (RSD) below 8% in all cases. For analysis of 100-mL sample, the method detection limits (LOD) ranged from 4.5 to 9.8 ng L(-1) and the limit of quantitation (LOQ) from 14.9 to 32.6 ng L(-1). To demonstrate the potential of the MIP obtained, a comparison with commercially available C(18) SPE was performed. Molecularly imprinted SPE showed higher recoveries than commercially available C(18) SPE for most of the compounds. These results showed the suitability of the MIP-SPE method for the selective extraction of a class of structurally related compounds such as natural and synthetic estrogens.     

Electrochemical studies and differential pulse polarographic analysis of lansoprazole in pharmaceuticals

The electrochemical reduction of lansoprazole was investigated by cyclic voltammetry and direct current and differential pulse polarography. The reduction potential was -1.32 V vs. Ag/AgCl with a dropping mercury electrode in a supporting electrolyte consisting of phosphate buffer (pH 9.0)-tetramethylammonium iodide (4 + 1). The reversibility of the electrode reaction and the type of limiting current were studied. The temperature coefficient and the diffusion constant were determined. A mechanism for the electrode reaction was proposed. A new simple and sensitive differential pulse polarographic method was also developed for the quantification of lansoprazole. A linear calibration graph was obtained in the range 0.04-11.35 micrograms ml-1. The limit of detection was 0.03 microgram ml-1 and the intra- and inter-day precisions were 0.84-2.32 and 0.72-3.09%, respectively. The developed method was applied to six different commercial pharmaceutical capsule preparations containing enteric-coated granules. The relative standard deviations ranged from 1.36 to 2.85%. Recovery studies for the accuracy of the method were performed by adding a synthetic mixture to known amounts of lansoprazole and the mean recovery was 100.45%. The data obtained from commercial preparations were compared with those from a published spectrophotometric method. No difference was found statistically.     

Application of multiwall carbon nanotubes-based matrix solid phase dispersion extraction for determination of hormones in butter by gas chromatography mass spectrometry

The multiwall carbon nanotubes (MWCNTs)-based matrix solid phase dispersion (MSPD) was applied for the extraction of hormones, including 17-α-ethinylestradiol, 17-α-estradiol, estriol, 17-β-estradiol, estrone, medroxyprogesterone, progesterone and norethisterone acetate in butter samples. The method includes MSPD extraction of the target analytes from butter samples, derivatization of hormones with heptafluorobutyric acid anhydride-acetonitrile mixture, and determination by gas chromatography-mass spectrometry. The mixture containing 0.30 g graphitized MWCNTs and 0.10 g MWCNTs was selected as absorbent. Ethyl acetate was used as elution solvent. The elution solvent volume and flow rate were 12 mL and 0.9 mL min(-1), respectively. The recoveries of hormones obtained by analyzing the five spiked butter samples were from 84.5 to 111.2% and relative standard deviations from 1.9 to 8.9%. Limits of detection and quantification for determining the analytes were in the range of 0.2-1.3 and 0.8-4.5 μg kg(-1), respectively. Compared with other traditional methods, the proposed method is simpler in the operation and shorter in the sample pretreatment time.     

SPE and HPLC monitoring of 17-β-estradiol in Egyptian aquatic ecosysetms

Solid-phase extraction and HPLC methods are described for monitoring of 17-β-estradiol residues in Egyptian aquatic ecosystems (water, fish, mollusks, sediment, and drinking water) at the Nile River, Suez Canal region, and northeast of Egypt. Molecular imprinted polymer was prepared and used in extraction. High performance liquid chromatography (HPLC) columns used were Supelcosil C₁₈ and Nucleosil C₁₈. The mobile phases used were different combinations of water and acetonitrile. The concentration of 17-β-estradiol in water, aquatic animals, and sediment samples were of 265.13–7988.12 µg/L, 0.503–96.167, and 0.775–11.884 µg/kg, respectively. Marine lake was contained with high levels of 17-β-estradiol (P < 0.05). Similarly, the Nile River downstream showed high levels of 17-β-estradiol. The detected concentrations in mollusks were significantly higher than those detected in fish. Tilapia fish did not show 17-β-estradiol. Contrarily, low concentrations were detected in the rivulet streams supplied by the Nile River. Besides, 17-β-estradiol was also detected in the sediments at low levels. Detection of 17-β-estradiol in the Egyptian ecosystems attracted attention toward heavy reliance on some esterogenic medicinal products in Egypt. The monitoring of 17-β-estradiol in other water bodies was recommended. Besides, the development of methodologies of bioremediation to eliminate 17-β-estradiol from the Egyptian and other water resources of the world was also suggested.     

Adaptation and validation of QuEChERS method for the simultaneous analysis of priority and emerging pollutants in sediments by gas chromatography—mass spectrometry

A Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method has been adapted and validated for the simultaneous determination of priority (16 PAHs, 12 PCBs and 7 organochlorine pesticides (OCPs)) and emerging (carbamazepine, 9 musks and 6 sunscreens) pollutants in sediments by Gas Chromatography-Mass Spectrometry (GC-MS). The sample preparation was adapted by modifying the nature of the extraction solvent and optimising clean-up and evaporation steps. The method was validated by the analysis of spiked estuarine and marine sediments. Analytical performances were evaluated in terms of linearity, accuracy, precision and detection limits. The method shows good linearity (coefficients of determination > 0.998) and repeatability (RSD < 10%). Obtained recoveries are acceptable, ranging from 62% to 131% for all the compounds. Detection limits are estimated to range from 0.01 ng/g to 3.18 ng/g. This developed method offers the ability to detect and quantify several priority and emerging pollutants at low concentration levels in sediments.     

Measurement uncertainty arising from trueness of the analysis of two endocrine disruptors and their metabolites in environmental samples. Part I: ultrasonic extraction from diverse sediment matrices

The validation of preconcentration strategies for the simultaneous determination of two endocrine disrupting compounds (EDCs) and their metabolites present in the aquatic environment including natural waters and freshwater sediments as well as the estimation of uncertainty arising from trueness using fully nested experimental designs are presented in a series of two papers. In this work, we present Part I of our ongoing study, the validation of an analytical method based on ultrasonic extraction of the target analytes from various freshwater sediments and the estimation of the method measurement uncertainty. The selected endocrine disruptors included two widely used herbicides, diuron (1-(3,4-dichlorophenyl)-3,3-dimethylurea) and linuron (3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea) and their common degradation products namely, 3,4-dichloroaniline (3,4-DCA), 1-(3,4-dichlorophenyl) urea (DCPU) and 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU). A high-performance liquid chromatography system coupled to UV-diode array detector (HPLC/UV-DAD) was used for the target analytes quantification. A fully nested experimental design was applied to study the measurement uncertainty arising from trueness by estimating proportional bias (in terms of recovery). The overall recoveries, that is, those determined by the nested experiments were in the range of 59.5-85.1%, except 3,4-DCA for which a low overall recovery of 29.0% was observed. The analytical method was shown to be linear over the studied range of concentrations (5-100 microg/kg), exhibiting satisfactory repeatability and reaching limits of detection usually in the 0.6-4.6 microg/kg range on dry sediment basis. The method used permitted the determination of the target EDCs and their metabolites in sediment samples collected from selected study stations in the region of Epirus (N.W. Greece) at the concentration levels demanded by current legislation.     

液相色谱同位素稀释串联质谱法测定人血清中17β-雌二醇含量

研究建立了以人血清中E2-16,16,17-d3为内标测定17β-雌二醇的液相色谱/串联质谱(ID-LC/MS/MS)方法。血清样品经固相萃取装置(SPE)提取雌二醇,乙酸乙酯萃取净化,吹干复溶后用10-乙基吖啶酮-2-磺酰氯(EASC)进行衍生。以Agilent Eclipse XDB-C18色谱分离柱,乙腈、水梯度洗脱,使用电喷雾三重四极杆串联质谱的多重反应监测模式测定,以校准曲线法进行定量。所建立的液相色谱同位素稀释串联质谱法(ID-LC/MS/MS)对于分析血清17β-雌二醇的批内、批间RSD分别为0.29%～0.73%和0.18%～0.28%,回收率为99.6%～100.2%,采用IFCC RELA比对(JCTLM比对)样品进行了方法比较,测定结果与其他实验室相比偏差在0.8%范围内。方法可作为人血清中17β-雌二醇含量测量参考方法。     

Quantitative analysis of active compounds in pharmaceutical preparations by use of attenuated total-reflection Fourier transform mid-infrared spectrophotometry and the internal standard method

A new method is presented for the quantitative analysis of compounds in pharmaceutical preparations Fourier transform (FT) mid-infrared (MIR) spectroscopy with an attenuated total reflection (ATR) module. Reduction of the quantity of overlapping absorption bands, by interaction of the compound of interest with an appropriate solvent, and the employment of an internal standard (IS), makes MIR suitable for quantitative analysis. Vigabatrin, as active compound in vigabatrin 100-mg capsules, was used as a model compound for the development of the method. Vigabatrin was extracted from the capsule content with water after addition of a sodium thiosulfate IS solution. The extract was concentrated by volume reduction and applied to the FTMIR-ATR module. Concentrations of unknown samples were calculated from the ratio of the vigabatrin band area (1321-1610 cm(-1)) and the IS band area (883-1215 cm(-1)) using a calibration standard. The ratio of the area of the vigabatrin peak to that of the IS was linear with the concentration in the range of interest (90-110 mg, in twofold; n=2). The accuracy of the method in this range was 99.7-100.5% (n=5) with a variability of 0.4-1.3% (n=5). The comparison of the presented method with an HPLC assay showed similar results; the analysis of five vigabatrin 100-mg capsules resulted in a mean concentration of 102 mg with a variation of 2% with both methods.     

Label-free aptamer-based electrochemical impedance biosensor for 17β-estradiol

A novel aptamer-based label-free electrochemical impedance spectroscopy biosensor for 17β-estradiol has been fabricated. The aptamers were firstly immobilized on the gold electrode through Au-S interaction; the aptamer probe was then bound with the addition of 17β-estradiol to form the estradiol/aptamer complex on the electrode surface. This leads to a significantly larger interfacial electron transfer resistance than that without the addition of 17β-estradiol. The change in the resistance had a linear relationship with 17β-estradiol concentration in the range of 1.0 × 10(-8) to 1.0 × 10(-11) mol L(-1), with a detection limit of 2.0 × 10(-12) mol L(-1). The biosensor showed high selectivity to 17β-estradiol and good stability. The designed biosensor has been applied to detect 17β-estradiol in human urine with satisfactory results.     

The determination of biperiden in plasma using gas chromatography mass spectrometry: pharmacokinetics after intramuscular administration to guinea pigs

A gas chromatographic-mass spectrometric (GC-MS) method has been developed for the analysis of the biperiden from plasma. The method utilizes 290 microl of plasma and a simple hexane extraction/clean-up procedure. Standard curves were linear over the range of 1.9-250 ng/mL. The range of correlation coefficients for the individual standard curves was 0.9984-0.9999; the largest coefficient of variation expressed as a percentage (% CV) was 11.5%. Precision and accuracy were examined by assessing between-day and within-day variability. For between-day precision, the % CVs ranged from 2.86 to 5.17%. Accuracy as expressed by percentage error ranging from -2.16 to 5.83%. The study for within-day precision demonstrated % CVs from 0.95 to 5.55% with accuracy from -3.37 to 2.45%. Applicability of the method was demonstrated by examining the pharmacokinetics of intramuscular (i.m.) biperiden as an anticonvulsant treatment in a guinea pig model for organophosphate (OP)-induced seizure activity. Mean pharmacokinetic parameter estimates were similar to literature values; selected mean pharmacokinetic parameter estimates were: apparent volume of distribution, 13.9 L/kg; half-life of elimination, 93 min; time to maximal plasma concentration, 27.4 min; and maximal plasma concentration, 32.22 eta g/mL. The time to maximal plasma concentration was found to be similar to the onset time for terminating OP-induced seizure activity in guinea pigs receiving biperiden as an anticonvulsant treatment. The studies indicate that the method affords the required precision, accuracy and sensitivity to assay biperiden at the doses utilized for these pharmacokinetic studies after i.m. administration to guinea pigs.     

Determination of steroid hormones in blood by GC–MS/MS

This paper presents the development, optimization and validation of a methodology to determine nine key steroid hormones (viz. pregnenolone, progesterone, dehydroepiandrosterone, androstenedione, testosterone, dihydrotestosterone, estrone, 17α-estradiol and 17β-estradiol) expressed in the steroidogenesis in biological fluids. The analytical method allows for the determination of steroid hormones in blood plasma and serum down to 0.08–0.16 ng/mL for estrogens, 0.20–0.36 ng/mL for androgens and 0.36–0.43 ng/mL for progestagens. These limits of detection were obtainable using a two-step solid-phase clean-up for fractionation and elimination of interfering lipids (fatty acids, phospholipids, glycerides and sterols) from the steroid hormones. The accuracy of the method was 50–112% in the range 0.10 to 2.00 ng/mL.     

超高效液相色谱法测定护手霜中5种不同的雌激素

建立了超声波萃取．超高效液相色谱快速测定护手霜中5种雌激素（雌酮,雌二醇,苯甲酸雌二醇,美雌醇,炔雌醇环戊醚）的分析方法,研究了萃取溶剂、萃取时间对萃取效率的影响,确立了流动相流速及色谱柱柱温等检测条件．化妆品以乙腈和水（20：80,V：V）为提取溶剂进行超声波萃取后用C18色谱柱分离,乙腈和水溶液为流动相,梯度洗脱,10min内完成5种雌激素的分离与检测．方法的检出限为0．016—0．031μg／mL,相对标准偏差均小于5．0％m=3）,5种雌激素的工作曲线的相关系数均高于0．992．化妆品的加标回收率在85％～95％之间．方法简单快速、灵敏度高、分离效果好,满足化妆品中雌激素分析的需要．     

粉末压片-X射线荧光光谱法测定富硅土壤和沉积物样品中的5种重金属元素

X射线荧光光谱法测定土壤和沉积物中的重金属具有简便、快速、准确等优点,但现有的环境行业标准方法不适用于SiO2含量大于80%的土壤和沉积物。为提高X射线荧光光谱法测定土壤和沉积物中的重金属在环境监测领域中的适用性,建立基于粉末压片-X射线荧光光谱法测定富硅土壤和沉积物中重金属的分析方法。通过选取富硅的土壤和沉积物标准物质提高校准曲线的测量范围以及优化各元素的测量条件,探讨基体效应和谱线重叠干扰、研究压片制样的最佳压力等途径,测定富硅土壤和沉积物中的Pb、Cr、Cu、Ni、Zn。结果表明在已优化的测定条件下,通过延长校准曲线的测量上限,保证待测元素含量在校准曲线范围内,同时采用经验系数法和康普顿散射内标法校正基体效应,可进一步提高方法的准确度和精密度。方法比对结果显示该方法的测定结果与原子吸收光谱法的测定结果无显著性差异。选用2种不同的富硅标准物质进一步验证方法的精密度和准确度,Pb、Cr、Cu、Ni、Zn的测定结果与标准物质认定值的对数误差为0.002~0.08,相对标准偏差为1.0%~4.6%。该方法的精密度和正确度满足土壤和水系沉积物环境监测分析的技术要求,具有良好的应用前景。     

An improved method for the simultaneous analysis of phenolic and steroidal estrogens in water and sediment

This paper describes an improved method for the extraction and analysis of seven endocrine disrupting chemicals with wide-ranging polarities from water and sediments using gas chromatography-tandem mass spectrometry (GC-MS/MS). The analytes were 4-tert-octylphenol, 4-nonylphenol, bisphenol A, estrone, 17β-estradiol, 17α-ethynylestradiol and 16α-hydroxyestrone. The optimised GC-MS/MS method produces increased selectivity and sensitivity compared to GC-MS, with limit of detection ranging from 0.01 to 0.49 ng L⁻¹ in water and from 0.05 to 0.14 ng g⁻¹ in sediment. Extraction from aqueous samples was performed by solid-phase extraction (SPE) and from sediment samples by microwave-assisted extraction (MAE). The improved method for the clean-up of sediment extracts carried out by SPE enhanced EDC recovery (86-102%) while reducing matrix interference and sample drying time. Derivatisation of final sample extracts was achieved using N,O-bis(trimethylsilyl)trifluoroacetamide and pyridine, and their stability was enhanced by reconstituting the derivatised extracts with hexane. The method was validated by spiking experiments which showed good recovery and reproducibility. The method was applied to samples taken from the Medway estuary in Kent, UK, where non-conservative behaviour of EDCs was demonstrated.     

Evaluation of comprehensive two-dimensional gas chromatography with micro-electron capture detection for the analysis of seven pesticides in sediment samples

A GC-μECD and a GC×GC-μECD method were developed for the analysis of pesticides in sediments. For 1D-GC, instrumental LOD and LOQ were found in the range from 0.60 to 2.31μgL(-1) and 1.83 to 5.62μgL(-1), respectively. For GC×GC method development two sets of columns were tested (DB-5/DB-17ms, and HP-50+/DB-1ms), and the best results were obtained with the set of columns DB-5/DB-17ms. Instrumental LOD and LOQ were found in the range from 0.08 to 1.07μgL(-1) and 0.25 to 3.23μgL(-1), respectively. The LOD for the GC×GC was about 36% lower than those obtained for the 1D-GC. Concentrations of 21.18μgkg(-1) through 1D-GC method and 3.34μgkg(-1) for GC×GC for trifloxystrobin were found in a sediment sample which was collected close to an area of rice plantation.