Quantitative analysis of estrogens in human urine using gas chromatography/negative chemical ionisation mass spectrometry

Ultrasound-Assisted Extraction, Followed by Gas Chromatography-Mass Spectrometry for the Simultaneous Quantification of Ethinyl Estradiol and Drospirenone in Contraceptive Formulations

Contraceptive tablets typically contain a combination of two synthetic versions of an estrogen and a progestogen, which work together to inhibit the ovulation process. An accurate and precise quantification of these components is essential for contraceptive producers. In this study, we have developed the first gas chromatography-mass spectrometry (GC-MS) method for the simultaneous quantification of 17α-ethinyl estradiol (EE) and drospirenone (DP) in contraceptive formulations. Under the final working conditions, analytes were extracted from the solid by ultrasound-assisted extraction (15 min) in methanol. The resulting suspension was diluted in ethyl acetate, subjected to centrifugation and, finally, the supernatant was directly injected into the GC-MS system. No derivatization reagents were utilized. To correct for instrumental variations, calibration was performed using the internal standard method, with cholesterol as the internal standard. A good linearity was achieved throughout the calibration range for both EE (3-12 µg mL^-1) and DP (300-1200 µg mL^-1), with R² values exceeding 0.99. Trueness, assessed in terms of percentages of recovery, was also found to be satisfactory for both analytes, with recovery rates of 106 ± 8% for EE and 93 ± 9% for DP. Furthermore, intra-day and inter-day precision studies yielded relative standard deviation values below 6% for both analytes. In terms of sensitivity, the instrumental limits of detection were 0.25 µg mL^-1 for EE and 6.6 µg mL^-1 for DP, and the instrumental limits of quantification 0.82 µg mL^-1 for EE and 22 µg mL^-1 for DP. The method was successfully applied to the analysis of contraceptive tablets from three different pharmaceutical companies. No differences were observed between the measured and the declared amount of active principle per tablet, demonstrating the applicability of the procedure. In addition, a stability study conducted on both the standards and sample extracts demonstrated that they can be stored at room temperature for a minimum period of seven days.

Optimization and validation of a GC-MS quantitative method for the determination of an extended estrogenic profile in human urine: Variability intervals in a population of healthy women

An analytical method based on GC-MS was developed for the determination of a wide panel of urinary estrogens, together with their principal metabolites. Because of the low concentration of estrogens in urine, an efficient sample pre-treatment was optimized by a design of experiment (DoE) procedure to achieve satisfactory sensitivity. A second DoE was built for the optimization of the chromatographic run, with the purpose of reaching the most efficient separation of analytes with potentially interfering ions and similar chromatographic properties. The method was fully validated using a rigorous calibration strategy: from several replicate analyses of blank urine samples spiked with the analytes, calibration models were built with particular attention to the study of heteroscedasticity and quadraticity. Other validation parameters, including the limit of detection, intra-assay precision and accuracy, repeatability, selectivity, specificity, and carry-over, were obtained using the same set of data. Further experiments were performed to evaluate matrix effect and extraction recovery. Then the urinary estrogen profiles of 138 post-menopausal healthy women were determined. These profiles provide a representation of physiological concentration ranges, which, in forthcoming studies, will be matched on the base of multivariate statistics with the urinary estrogenic profile of women with breast or ovarian cancer.

Seasonal variation and the distribution of endocrine-disrupting chemicals in various matrices affected by algae in the eutrophic water environment of the pearl river delta, China

The seasonal variation and distribution among different matrices of endocrine-disrupting chemicals (EDCs) were investigated in the eutrophic water ecosystem of the Pearl River Delta, Guangdong, China. The chlorophyll a (Chl a) levels were generally higher in summer than in spring; however, the concentrations of 4-tert-octylphenol (OP), 4-nonylphenol (NP), and bisphenol A (BPA) in surface water were generally higher in spring (oligotrophic) than in summer (eutrophic). The levels of EDCs in SPM were lower in spring than in summer, a pattern seen in the seasonal variation of Chl a and particulate organic carbon (POC). The seasonal variations of EDCs in water bodies with different levels of eutrophication were analyzed in several dimensions including sediment, POC, algae and fish bile. The log K_oc for SPM/water was higher in summer than in spring. The log K_oc values for NP, OP, and BPA exhibited the following trends between matrices: colloid/water > sediment/water > SPM/water > algae/water, colloid/water > sediment/water > algae/water > SPM/water, and colloid/water > algae/water > sediment/water > SPM/water. The EDCs levels were different in fish tissues with the order bile > liver > muscle, with the concentrations being an order of magnitude higher in bile than in liver and an order of magnitude higher in liver than in muscle. The sequence of the bioconcentration factor (log BCF) for bile/water and liver/water was NP < OP < BPA in eutrophic conditions, but NP > OP > BPA in oligotrophic conditions. The order in eutrophic conditions was the same as the log BCF and log K_oc for algae/water, indicating that the accumulation of EDCs in water bodies could be affected by algae, which could be one of the reasons of the seasonal variation of EDCs in water.

Derivatization gas chromatography negative chemical ionization mass spectrometry for the analysis of trace organic pollutants and their metabolites in human biological samples

Gas chromatography negative chemical ionization mass spectrometry (GC-NCI-MS) is a preferred instrumental approach for the trace and ultra-trace analysis of various toxic organics and their metabolites in human biological fluids. Specifically, the method has played an important role in the highly sensitive and specific quantitative detection of persistent highly halogenated compounds in environmental matrices and biota during the past few decades. However, for the analysis of toxic metabolites with active hydrogen atoms, such as acids, alcohols, and phenolic compounds, from biological matrixes or organics without electronegative atoms or groups, a derivatization step is often needed prior to GC analysis. Such derivatization aims to change the properties of targets to improve their separation, increase their volatility, and enhance the sensitivity of instrumental detection. This review summarizes three derivatization strategies commonly used for GC methods, i.e., alkylation, silylation, and acylation, together with their application combined with GC-NCI-MS for the high sensitivity analysis of toxic organic metabolites in the human body. The advantages and disadvantages of each derivatization method and potential directions for future applications are discussed. Given the broad variety of applications as well as the compound-specific sensitivity for the ultra-trace analysis of target xenobiotics in human biological fluids, subsequent studies are required to develop convenient, faster derivatization procedures and reagents better suited for routine analysis. Graphical abstract.

Individual and cyclic estrogenic profile in women: Structure and variability of the data

The concentration of estrogens in the body fluids of women is highly variable, due to the menstrual cycle, circadian oscillations, and other physiological and pathological causes. To date, only the cyclic fluctuations of the principal estrogens (estradiol and estrone) have been studied, with limited outcome of general significance. Aim of the present study was to examine in detail the cyclic variability of a wide estrogens' panel and to interpret it by multivariate statistics. Four estrogens (17α-estradiol, 17β-estradiol, estrone, estriol) and eleven of their metabolites (4-methoxyestrone, 2-methoxyestrone, 16α-hydroxyestrone, 4-hydroxyestrone, 2-hydroxyestrone, 4-methoxyestradiol, 2-methoxyestradiol, 4-hydroxyestradiol, 2-hydroxyestradiol, estriol, 16-epiestriol, and 17-epiestriol) were determined in urine by a gas chromatography - mass spectrometry method, which was developed by design of experiments and fully validated according to ISO 17025 requirements. Then, urine samples collected every morning for a complete menstrual cycle from 9 female volunteers aged 24-35 years (1 parous) were analysed. The resulting three-dimensional data (subjects × days × estrogens) were interpreted using several statistical tools. Parallel Factor Analysis compared the estrogen profiles in order to explore the cyclic and inter-individual variability of each analyte. Principal Component Analysis (PCA) provided clear separation of the sampling days along the cycle, allowing discrimination among the luteal, ovulation, and follicular phases. The scores obtained from PCA were used to build a Linear Discriminant Analysis classification model which enhanced the recognition of the three cycle's phases, yielding an overall classification non-error rate equal to 90%. These statistical models may find prospective application in fertility studies and the investigation of endocrinology disorders and other hormone-dependent diseases.

Distribution and bioconcentration of endocrine disrupting chemicals in surface water and fish bile of the Pearl River Delta, South China

The distribution and bioconcentration of endocrine disrupting chemicals (EDCs) in water, algae, and wild carp bile of the Pearl River Delta (PRD), South China were investigated. 4-tert octylphenol (OP), 4-nonylphenol (NP), and bisphenol A (BPA) (unit, ng L(-1)) in water were in the ranges of 1-14, 117-865, and 4-377, those (ng g(-1) dry weight) in algae were in the ranges of 2-13, 53-282, and 16-94, and those (ng g(-1)) in carp bile were in the ranges of 14-39, 950-4648, 70-1020, respectively. Estrone (E1) and 17α-ethinylestradiol (EE2) in water ranged from <LOQ to 1.58 ng L(-1) and from <LOQ to 3.43 ng L(-1), respectively. In bile and algae, E1 ranged from nd to 30 ng g(-1), but EE2 was not detected. The E2 activity equivalents (EEQs) ranged from 1.20 to 10.97 ng g(-1) in carp bile and from 0.07 to 8.06 ng L(-1) in water. The EEQs in carp bile were significantly related to those in water, illustrating that occurrence of EDCs in carp bile can reflect that in ambient water in the PRD region. The bioconcentration factors (BCF, L kg(-1)) of OP, NP, BPA, and E1 in algae were in the ranges of 482-7251, 131-740, 2846-12979, and undetectable, respectively, and those in carp bile were in the ranges of 1500-12960, 1648-11137, 3583-14178, and 13208-39623, respectively. The phenolic EDCs can be accumulated by wild carp bile and algae in the investigated aquatic ecosystems, which is also affected by the degree of the eutrophication. This study for the first time reported EDCs in carp bile and algae collected from the PRD, China.

Development and validation of UPLC-MS/MS method for simultaneous determination of gestodene and ethinyl estradiol in rat plasma

A selective and sensitive ultra-performance liquid chromatography method with tandem mass spectrometric detection for simultaneous determination of gestodene (GES) and ethinyl estradiol (EE) in rat plasma was developed and validated. GES, EE and the internal standard, norgestrel, were extracted with ethyl acetate, derivatized (EE only) with dansyl chloride and then back-extracted into diethyl ether-hexane (2:1, v/v). The separation was performed on an ACQUITY UPLC BEH C(18) column with gradient elution using mobile phase consisting of acetonitrile and water (both containing 0.1% formic acid). The detection was carried out by means of electrospray ionization (ESI) mass spectrometry in positive ion mode with multiple-reaction monitoring. Calibration curves of GES and EE were linear (r(2) >or= 0.99) over the concentration ranges 1.59-159 and 0.196-78.4 ng/mL, respectively. The intra- and inter-day precisions were not more than 6.9 and 12.9% for GES and 10.6 and 9.0% for EE, and the accuracies were -2.5-8.0% for GES, and -7.2-0.19% for EE, respectively. The method herein described was superior to previous methods and was applicable to the pharmacokinetic study of GES and EE in rats.

Determination of phenolic endocrine disrupting chemicals and acidic pharmaceuticals in surface water of the Pearl Rivers in South China by gas chromatography-negative chemical ionization-mass spectrometry

An analytical method for phenolic endocrine disrupting chemicals and acidic pharmaceuticals in river water was developed using gas chromatography mass spectrometry (GC-MS) coupled with negative chemical ionization (NCI) technique, and used for the determination of these compounds in the Pearl Rivers (Liuxi, Zhujiang and Shijing Rivers). Derivatization using pentafluorobenzoyl chloride (PFBOCl) and pentafluorobenzyl bromide (PFBBr) before GC-MS analysis were applied and optimized for phenolic compounds and acidic compounds, respectively. The target compounds were analyzed for river waters from the upstream to downstream of the Pearl Rivers. Phenolic compounds 4-tert-octylphenol (4-t-OP), 4-nonylphenol (4-NP), bisphenol-A (BPA), estrone (E1), estradiol (E2) and triclosan (TCS) were detected at trace or low levels in the water samples from Liuxi River and Zhujiang River. Diethylstilbestrol (DES) was not detected in the Pearl Rivers. The highest concentrations of the phenolic compounds were found in Shijing River, and they were 3150 ng/L for 4-t-OP, 11,300 ng/L for 4-NP, 1040 ng/L for BPA, 79 ng/L for E1, 7.7 ng/L for E2 and 355 ng/L for TCS, respectively. Only a few acidic pharmaceuticals were detected at low concentrations in water from Liuxi River and Zhujiang River, but the highest concentrations for the acidic pharmaceuticals were also found in Shijing River. The highest concentrations detected for clofibric acid, ibuprofen, gemfibrozil, naproxen, mefenamic acid and diclofenac were 17 ng/L, 685 ng/L, 19.8 ng/L, 125 ng/L, 24.6 ng/l and 150 ng/L, respectively. The results suggest Liuxi and Zhujiang Rivers are only slightly contaminated and can be used as drinking water sources, but Shijing River is heavily polluted by the wastewater from nearby towns.

Stable isotope-coded quaternization for comparative quantification of estrogen metabolites by high-performance liquid chromatography-electrospray ionization mass spectrometry

A fast and sensitive LC-ESI-MS method is described for the comparative quantification of 16 estrogen metabolites based on the derivatization of estrogens with a novel derivatizing reagent, N-methyl-nicotinic acid N-hydroxysuccinimide ester (C1-NA-NHS). The process introduces a quaternary amine to the analytes, making the analytes permanently charged regardless of the pH of the high-performance liquid chromatography (HPLC) mobile phase. This quaternization resulted in a highly efficient separation of 16 estrogen metabolites in 7 min at a detection level below 1 ng/mL. By using a deuterated derivatizing reagent (C1-d(3)-NA-NHS), a complete set of deuterated standards was utilized and used as internal standards in a comparative quantification and recovery study, demonstrating acceptable results over a wide concentration range. A pooled breast cancer serum sample was analyzed using the described method, and 15 estrogens were detected in the range of 80-530 pg/mL.

Horizontal distribution of steroid estrogens in surface sediments in Tokyo Bay

A monitoring survey was conducted to investigate the distribution of steroid estrogens and their conjugates in surface sediments of Tokyo Bay for the first time, which is known as one of the most heavily polluted marine embayments in the world. The surface sediment samples were collected at 20 locations covering the whole area of Tokyo Bay and analyzed for steroid estrogens and their conjugates using liquid chromatography-tandem mass spectrometry. The concentrations of 17beta-estradiol (beta-E2) and estrone (E1) ranged from ND (below the detection limit; <0.07) to 0.59 and from 0.05 to 3.60 ng g-1 dry, respectively. Those concentrations were higher in the northern part of the bay, which is directly receiving huge quantities of pollutants from adjacent rivers containing a large amount of municipal and industrial wastewater. 17alpha-Estradiol (alpha-E2) and estrone-3-sulfate (E1-3S) were detected in some of the samples, whereas neither of the other conjugates, estriol (E3) or 17alpha-ethynylestradiol (EE2), was found.

Fully automated liquid chromatography–mass spectrometry determination of 17β-estradiol in river water

Surface modified molecularly imprinted polymers (SM-MIPs) for 17beta-estradiol (E2), utilizing 6-ketoecradiol as a pseudo template were prepared. MIPs for E2 were synthesized using 4-vinyl pyridine and ethylene dimethacrylate as a functional monomer and cross-linking agent, respectively. MIPs selectively retained E2 and provided excellent chromatographic resolution from interfering compounds inherent in river water sample matrices. Therefore, freshly prepared MIPs were applied to quantitative mass spectrometric (negative electrospray ionization mode) detection of low levels of E2 in river water sample. In order to pre-concentrate the target compound for HPLC analysis, column switching was coupled with a pretreatment column packed with the MIPs. The repeatability of actual determinations of river water sample, in which background E2 was not detected, spiked with 50 ng/L of E2 was 2.2% RSD with a detection limit and qualification limit of 1.8 and 5.4 ng/L, respectively. Surface modification of MIP particlefs packed in the pretreatment column provided selective affinity and on-line concentration of low levels of E2 while simultaneously eliminating sample matrix interference, resulting in a significant increase in sensitivity and reproducibility for liquid chromatography-mass spectrometry analysis of E2 in river water sample.

An isotope dilution gas chromatographic-mass spectrometric method for the simultaneous assay of estrogens and phytoestrogens in urine

The metabolism of endogenous estrogens is complicated and certain metabolic patterns may reflect an individual risk of estrogen-dependent diseases such as breast cancer. Since the 1960s we have been constantly involved in developing estrogen profiling methods, in the beginning using gas chromatography and later gas chromatography-mass spectrometry (GC-MS) in the selected ion monitoring mode (SIM) and finally utilizing isotope dilution (ID-GC-MS-SIM). The addition of the dietary phytoestrogens to the profile rendered the method even more complicated. The present work presents the final estrogen profile method for 15 endogenous estrogens, four lignans, seven isoflavonoids and coumestrol in one small urine sample (1/150th of a 24 h human urine sample, minimum 2.5-5 ml) with complete validation including investigations as to the precision, sensitivity, accuracy and specificity. The method does not include the minimal amounts of unconjugated estrogens in urine. It may also be used for animal (e.g. rat and mouse) urine using a minimum of 2 ml of usually pooled sample. Despite its complexity it was found to fulfill the reliability criteria, resulting in highly specific and accurate results.

Validation of a gas chromatography–mass spectrometry method for the determination of pg/ml levels of 17β-estradiol and 17β-trenbolone in bovine serum

A method for the quantitation of pg/ml levels of 17beta-estradiol and 17beta-trenbolone in bovine serum by gas chromatography/electron-capture mass spectrometry has been developed and validated. Using the area ratios of the integrated molecular-ion peaks of the analytes to their corresponding deuterated internal standards, [2,4,16,16-2H4] 17beta-estradiol (17beta-estradiol-d(4)) and [16,16-2H2] 17beta-trenbolone (17beta-trenbolone-d(2)), and non-weighted linear regression, two calibration curves per analyte; 5-50 and 50-500 pg/ml for 17beta-estradiol in sera, and 25-250 and 250-2500 pg/ml for 17beta-trenbolone in sera, respectively, were constructed. Splitless injection of 200 fg 17beta-estradiol and 1000 fg 17beta-trenbolone could be detected and quantified. Tested batches of control bovine sera did not exhibit interference for 17beta-trenbolone, and showed expected background presence of endogenous 17beta-estradiol. Intra-day residual errors did not exceed 20%, and regression correlations were greater than 0.99. Intra-day precision data was similar to inter-day precision data. Using this method, 16 samples can be processed within one working day.

Validation of a simple, sensitive method for the determination of β-estradiol in bovine urine using gas-chromatography negative-ion chemical ionization mass spectrometry

A new method is presented for the analysis of 17[small beta]-estradiol in bovine urine. After deconjugation, the sample is cleaned up using an OASIS[trade mark sign] HLB disposable cartridge and extracted into 1-chlorobutane. The hormone is derivatized using pentafluorobenzoyl chloride. The derivatized estradiol is quantitated using gas-chromatography negative-ion chemical ionization mass spectrometry. Calibrations, obtained using spiked blank urine, are linear in the range of 100-1000 pg mL(-1) with CC[small alpha] approximately 170 pg mL(-1) and CC[small beta] of 287 pg mL(-1). Recoveries are in the range of 80 to 130%. The method is rugged, rapid and sensitive when compared to other hormone methods.

Liquid chromatography-tandem mass spectrometry assay for simultaneous measurement of estradiol and estrone in human plasma

BACKGROUND

Estradiol (E2) and estrone (E1) measurements form an integral part of the assessment of female reproductive function and have expanding roles in other fields. However, many E1 and E2 immunoassays have limited functional sensitivity, suffer from cross-reactivity, and display poor intermethod agreement. To overcome these problems, we developed a sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the simultaneous measurement of E1 and E2.

METHODS

After dansyl chloride derivatization, samples were separated by fast gradient chromatography and injected into a tandem mass spectrometer after formation of positive ions with atmospheric pressure chemical ionization. The limits of detection and quantification, recovery, linearity, precision, and reference intervals were determined, and performance was compared with several immunoassays.

RESULTS

Total run time per sample was 5 min. The multiple-reaction monitoring ion pairs were m/z 506/171 for 3-dansyl-estradiol and m/z 504/171 for 3-dansyl-estrone. The limits of detection for E1 and E2 were 12.9 pmol/L (3.5 ng/L) and 10.3 pmol/L (2.8 ng/L), respectively. Interassay imprecision (CV) was 4-20% (n = 20). The limits of quantification (functional sensitivities) for E1 and E2 were 44.1 pmol/L (11.9 ng/L) and 23.2 pmol/L (6.3 ng/L), respectively. The assay was linear to >2200 pmol/L ( approximately 600 ng/L) for each analyte. Recoveries were 93-108% for E1 and 100-110% for E2. No cross-reactivity was observed. Method comparison with several immunoassays revealed that the latter were inaccurate and prone to interferences at low E1 and E2 concentrations.

CONCLUSIONS

LC-MS/MS allows rapid, simultaneous, sensitive, and accurate quantification of E1 and E2 in human serum.

Measurement of endogenous estrogens: analytical challenges and recent advances

Recent developments in the analysis of endogenous estrogens (including both free and conjugated estrogens) are reviewed. Largely due to urging by some cancer researchers, new demands are now being placed on such measurements in terms of sensitivity, throughput, multi-analyte detection and accuracy. Especially high sensitivity is required for detecting estrogens in serum from postmenopausal women, children and men, where concentrations at the low pg/ml level are encountered, and one would prefer to test much less than 1 ml of serum. Aside from throughput, meeting all of these demands may be beyond the reach of immunoassay, the method that has created and continues to dominate this field. Both HPLC and GC versions of mass spectrometry are emerging that have some potential to improve the testing of physiological samples for endogenous estrogens. The following topics are covered in this review: related analyses (e.g. detection of estrogens in environmental samples such as water, where 1-1 samples can be collected to provide ng amounts of estrogens); structure and metabolism of estrogens; biological actions (with an emphasis on their role in cancer); immunoassays; HPLC with electrochemical detection; GC-ECD; and various forms of mass spectrometry.

Derivatisation and gas chromatography-chemical ionisation mass spectrometry of selected synthetic and natural endocrine disruptive chemicals

Methods for ultra trace detection of endocrine disruptive chemicals (EDCs) are needed because of their low levels of impact. Twenty-one EDCs were selected, including 17beta-estradiol, 17alpha-ethinylestradiol, 17beta-testosterone and bisphenol A. Derivatisation with eight different fluorine containing compounds was examined. All EDCs could be derivatised automatedly (autosampler) with heptafluorobutyric acid (HFB) anhydride and trifluoroacetic acid (TFA) anhydride, respectively. The detection of these HFB and TFA derivatives in different chemical ionisation modes was studied. Fourteen different reagent gases, including methane, ammonia, acetone and water, were tested with the HFB and TFA derivatives in the negative chemical ionisation mode. Furthermore both types of derivatives were measured in positive chemical ionisation mode. Methane or water provide a good detection of all 21 TFA derivatives and create mass spectra with few fragmentation and characteristic mass peaks. This could serve as a basis for tandem or multiple mass spectrometric measurements.

Determination of estrogens and their conjugates in water using solid-phase extraction followed by liquid chromatography-tandem mass spectrometry

An analytical procedure for the determination of steroid estrogens and their conjugates was developed and applied to aqueous environmental samples. The analytes of 15 compounds were solid-phase extracted and fractionated into two fractions: one containing unconjugated (free) steroids and the other containing conjugates (sulfates and glucuronides). Identification and quantification were carried out using liquid chromatography coupled with tandem mass spectrometry. The recoveries for each compound ranged from 57 to 116% and reproducibilities represented as RSD ranged from 2.9 to 17%. Some of the sulfates and free compounds were detected in environmental samples, whereas most of the conjugates were below the detection limits.

Review: Derivatization in mass spectrometry--2. Acylation

The present review is devoted to acylation as a widely employed derivatization procedure for protection of OH (alcohols, polyols, phenols, enols), SH (thiols) and NH (amines, amides) groups in order to increase volatility, improve chromatographic properties and, if possible, improve mass spectral properties of derivatives. Chemical aspects of derivatization and various acylating agents are characterized. Mass spectral [electron ionization (EI), chemical ionization (CI) and negative-ion (NI) CI] properties of derivatives that are helpful in identification, structure elucidation and quantitative determination of the analyzed compounds are discussed. Some recent analytical applications of the procedure in synthetic organic chemistry, clinical chemistry, environmental chemistry etc. are summarized.

The use of a thermally reversible bond for molecular imprinting of silica spheres

A silica monomer-estrone complex (EstSi) having a thermally cleavable urethane bond and a cross-linkable triethoxysilane group was synthesized. From EstSi and TEOS, spherical silica particles with sizes of 1.5-3 mum were prepared. The template molecules were removed from the silica matrix by heating at 180 degrees C in DMSO in the presence of water, generating a cavity with an amino group. The control silica particles that had the same sizes and shapes were obtained with aminopropyl triethoxysilane and TEOS. When ethylene glycol was added in place of H2O, an ethyl alcoholic group was formed in the cavity. Their recognition ability and specific binding for estrone were characterized by uptake experiments. The estrone-imprinted silica particles showed a much higher recognition ability than the control silica particles and higher selectivity for estrone than testosterone propionate.

Analysis of estrogens in river water and effluents using solid-phase extraction and gas chromatography-negative chemical ionisation mass spectrometry of the pentafluorobenzoyl derivatives

A procedure was developed for the analysis of estrogens in environmental water and effluents. Samples were extracted by passing through polymer-impregnated solid-phase extraction discs or C18 cartridges, followed by gas chromatography-negative chemical ionisation mass spectrometry of the pentafluorobenzoyl derivatives. The derivatives were stable and gave diagnostic negative molecular ions as the base peak for each of the major estrogens studied. The absolute recovery of estrogens spiked into clean groundwater using the disc procedure was 84-116% at the 10 ng l(-1) level (calculation not based on use of internal standards). Using doubly deuterated estradiol as internal standard added prior to extraction, the % relative standard deviation of estrogen extraction and analysis in spiked groundwater at the 10 ng(-1) level was 2.6-9.8%. Detection limits were 0.2 ng l(-1) or below for the major estrogens, based on a 2.5 litre sample. The most abundant estrogen was estrone, with concentrations over the range 6.4-29 ng l(-1) in effluents, and 0.2 to 17 ng l(-1) in water from the River Thames.