Trends in sensitive electrochemical sensors for endocrine disruptive compounds

The endocrine system that provides communication and maintains homeostasis, is an important part of the body. Any defects or disruptions that affect the endocrine system may cause serious problems in the actions and functions of the body. Endocrine disruptive chemicals (EDCs) are exogenous chemicals or mixtures of chemicals that affects normal functions of the endocrine system by interfering with endogenous hormones and hormonal pathways and disrupting homeostasis. Numerous compounds are considered as endocrine disruptors such as bisphenols (BPs), phthalates, pesticides etc. and they are widely used for industrial purposes in many commercial products. Therefore, human exposure is almost inevitable. Besides that, EDCs may cause environmental pollution and are found in surface waters, wastewater, soil etc. To prevent exposure and hazardous effect, there are legislative regulations including restrictions and prohibitions of the use of EDCs. Due to these reasons; it is crucial to develop highly sensitive, low-cost, easy-to-use, and rapid sensors for the determination of EDCs in commercial and environmental samples. Although there are mostly chromatographic and spectrometric methods for the EDCs monitoring, electrochemistry surpasses them with advantageous properties such as easy application procedure, high sensitivity, very low limit of detection (LOD) values and low-cost.In this review, major groups of EDCs will be explained with their recent and novel electrochemical sensor applications for their detection in commercial and environmental samples.     

Determination of serotonin and bufotenin as their dansyl derivatives.

A method is described which permits the determination of serotonin and bufotenin in the same tissue sample. It comprises the following steps: (a) tissue extraction with acetone-0.1 M hydrochloric acid (19:1); (b) reaction of the tissue extract with dansyl (Dns) chloride; (c) pre-separation of O-Dns-bufotenin from O,N-bis-Dns-serotonin and other Dns-amides on a small silica gel column (this step is dispensable if only serotonin or bufotonin is being determined); (d) TLC separation of O-Dns-bufotenin and O,N-bis-Dns-serotonin from other Dns derivatives; (e) quantitative evaluation of the separated compounds by fluorimetry for O-Dns-bufotenin and by fluorimetry or mass spectrometry for the serotonin derivative. The photometer response is linear within the range 0.1-300 nmole. With the mass spectrometric method, 2 pmole of O,N-bis-Dns-serotonin could be determined with a standard deivation of +/-9%. The recovery of the amines from tissue was better than 85%. Reserpine treatment of toads caused a concomitant decrease in serotonin and bufotenin in the brain, but not in the skin of the animals. Repletion of bufotenin in the brain occurs at a higher rate than the repletion of the serotonin pool.     

Simultaneous determination of pharmaceuticals, endocrine disrupting compounds and hormone in soils by gas chromatography-mass spectrometry

Analytical methods have been developed for simultaneous determination of six different pharmaceuticals and personal care products (PPCPs) (clofibric acid, ibuprofen, naproxen, ketoprofen, diclofenac, and triclosan), three endocrine disrupting compounds (EDCs) (4-tert-octylphenol, 4-n-nonylphenol, and bisphenol A (BPA)) and one estrogenic compound (estrone) in soil matrix. The soils were extracted by different solvents with the help of an ultrasonic treatment at 42 kHz, followed by a solid phase extraction (SPE) as a cleanup procedure. The purified extracts were derivatized with N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBSTFA) and then analyzed by GC-MSD (SIM mode). The method was evaluated by testing the following variables: initial spiking levels, extraction solvents, solvent volumes, and soil types (sandy and clay soils). For 5 g of soil, four successive extraction steps with the mixture of acetone-ethyl acetate provided satisfactory recoveries. In the sandy soil, the recoveries of all the compounds were from 63.8 to 110.7% for the spiking level of 100 ng/g dry soil, and from 52.2 to 108.2% for 5 ng/g dry soil, respectively. Result was similar for the clay soil. The precision across all recoveries was high, suggesting that this method has a good reproducibility. The method was successfully employed to soil samples collected from a golf course irrigated with reclaimed wastewater in southern California, and resulted in the detection of clofibric acid, ibuprofen, naproxen, triclosan, bisphenol A, and estrone at ng per gram dry weight concentration levels. The method is robust and simple, and provides straightforward analyses of these current-emerging trace organic pollutants in solid matrices.     

Simultaneous determination of endocrine disrupting phenolic compounds and steroids in water by solid-phase extraction-gas chromatography-mass spectrometry

A solid-phase extraction (SPE)-gas chromatography (GC)-mass spectrometry (MS) analytical method for the simultaneous separation and determination of endocrine disrupting chemicals (EDCs) from water samples is described in detail. Important and contrasting EDCs including estrone, 17beta-estradiol, 17beta-ethynylestradiol, 16beta-hydroxyestrone, 4-nonylphenol, bisphenol A and 4-tert-octylphenol were selected as the target compounds. The SPE technique, followed by the derivatisation with bis (trimethylsilyl) trifluoroacetamide was used for the extraction recoveries of target compounds from water samples. A number of parameters that may affect the recovery of EDCs, such as the type of SPE cartridges, eluents, as well as water properties including pH value, and concentration of salts and humic substances were investigated. It is shown that the Oasis cartridges produced the best recoveries of target EDCs while ethyl acetate was efficient in eluting EDCs from SPE cartridges. The recovery of some EDCs was enhanced by the addition of salt, but reduced by the increase in pH value and humic acid concentration. The optimised method was further verified by performing spiking experiments in natural river water and seawater matrices, with good recovery and reproducibility for all the selected compounds. The established method was successfully applied to environmental water samples from East and West Sussex, UK, for the determination of the target EDCs.     

Determination of amine-containing phosphonic acids and amino acids as dansyl derivatives

Conditions are selected for the analytical separation of (N-phosphonomethyl glycine), products of its microbiological conversion, glutamic acid, and alanine as dansyl derivatives using reversed-phase HPLC: column (250 × 4.6 mm) ReproSil-PAH EPA; mobile phase, methanol + 20 mM CH₃COONa (pH 5.1) (20: 80); rate of mobile phase, 1 mL/min; working detector wavelength, 330 nm. The duration of separation is 35 min. The lower limits of the analytical range (in ng) for dansyl derivatives are as follows: glyphosate, 8.2; aminomethyl phosphonic acid, 24.2; glutamic acid, 9.4; alanine, 12.6: glycine, 17.7; and sarcosine, 19.3. The TLC study of dansyl derivatives of amino acids was performed on sorbfil plates PTSH-P-V using two-dimensional chromatography in the systems ethyl acetate-isopropanol-24% aqueous ammonia (45: 35: 20) in the first direction and chloroform-methanol-acetic acid (25: 5: 1) in the second one. For determining phosphonic acids (glyphosate and aminomethyl phosphonic acid), a version of one-dimensional chromatography with the sequential use of two systems, chloroform-methanol-acetic acid (25: 5: 0.2) and ethanol-24% aqueous ammonia (7: 3), was proposed.     

High-speed analysis of dansyl derivatives of polyamines

Summary Analytical conditions for the high-speed, reversed-phase, liquid chromatographic of a diamine (putrescine) and polyamines (spermine and spermidine) were determined. Various elution modes were employed using the same mobile phase constituents: 20mM sodium heptane sulfonate and 20mM acetic acid as solvent A and, pure acetonitrile as solvent B. Samples were derivatized with dansyl chloride before injection.Under isocratic conditions, the separation of the three polyamines was achieved in 7 min. The use of a linear elution gradient led to the same analytical time but with a better resolution of the putrescine peak from non-polyamine frontal peaks. For these measurements, the sample size was 5l. This volume was increased to 20l and the use of a steep gradient combined with the peak-compression technique allowed a fast analysis in 2–3 minutes, which may be compared with a 30 min run time necessary when a conventional column is used.     

多类环境内分泌干扰物高效共同测定项目总结报告

环境中的内分泌干扰物质种类多样、浓度低且来源广、危害大,对环境中的内分泌干扰物进行及时准确检测,能有预防环境中的内分泌干扰物造成的危害,是对内分泌干扰物进行预防和治理的关键步骤。     

HPLC determination of catabolic amines in silage using their dansyl derivatives and an electrochemical detector

Summary The use of the electrochemical detector (EC) in the high performance liquid chromatography (HPLC) of dansyl derivatives of biogenic amines is reported. Isocratic and gradient elution patterns of synthetic mixtures of putrescine, cadaverine, 1,6-diaminohexane, tryptamine, histamine, tyramine, spermine and spermidine on a reversed phase column are shown. Hydrodynamic voltammograms of standard compounds are presented. The detection limits of the EC are compared with those of ultraviolet and spectrofluorimetric detectors. A chromatographic profile of amines from the proteolytic catabolism of maize silage byClostridia is shown.Presented at the 17th International Symposium on Chromatography, September 25–30, 1988, Vienna, Austria.     

Measurement of neutral sugars in glycoproteins as dansyl derivatives by automated high-performance liquid chromatography

Automated high-performance liquid chromatography was used to analyse dansylhydrazine derivatives of neutral sugars in unfractionated acid hydrolysates of four well-characterized glycoproteins: fetuin, ovalbumin, alpha-1-acid glycoprotein and bovine submaxillary mucin. After a simple single-step derivatization at 65 degrees C the sugar derivatives in protein hydrolysates chromatographed as single peaks on reversed-phase C18 columns. The isocratic solvent consisted of 20% (v/v) aqueous acetonitrile containing 0.01 M formic acid, 0.04 M acetic acid and 0.001 M triethylamine. The triethylamine significantly increases the sugar peak height at 254 nm. Repeated automatic sample injection without deterioration of column performance or interference from dansyl hydrazine is not possible with published methods, but was achieved by cleaning the column between each analysis with a solvent of 20% (v/v) acetonitrile and 80% (v/v) methanol. Hydrolysis with 2 M trifluoroacetic acid is superior to 2 M hydrochloric acid for both sugar recovery and convenience but must continue for 6-8 h at 105 degrees C to ensure complete sugar release. We confirmed that mannose is present in most preparations of human high-molecular-weight salivary glycoproteins, and also examined purified bovine skin proteodermatan sulphate. p-Nitrophenylhydrazine derivatives of neutral sugars are readily produced, but do not chromatograph as successfully as the dansyl derivatives while phenylhydrazine derivatives are not easily produced at 65 degrees C. Further development of the method should be possible by producing other hydrazine derivatives of neutral sugars.     

Heterocyclic compounds XII. Quinazoline derivatives as potential antifertility agents

Several quinazoline derivatives incorporating a trans-stillbene moiety were synthesized as potential post-coital antifertility agents. Some of these compunds showed low level activity in rats.     

Thin layer chromatography of dansyl and dinitrophenyl derivatives of amino acids. A review

The dinitrophenyl (DNP) derivatives of amino acids have found continual application in protein sequencing since Sanger used them for the first time for the sequencing of insulin. Dansyl derivatives of amino acids have been widely used in protein sequencing because of their fluorescent nature. The success of protein sequencing largely depends upon correct identification of such derivatives. The choice for the method of identification is related to cost, the availability of instrumentation and to the sensitivity needed for the analysis. Thin layer chromatography (TLC) is simple and has several advantages over other chromatographic methods. Therefore the literature after 1972 is reviewed for TLC analysis of dansyl- and DNP-amino acids, the two important amino acid derivatives required for identifying protein sequences. Additionally, the literature on the TLC resolution of enantiomeric mixtures of dansyl amino acids is reviewed. Application of various adsorbents, composition of solvent systems and other experimental conditions together with successful resolution data have been discussed. TLC provides a direct and inexpensive method for the resolution of enantiomers, and is fast becoming a sensitive instrumentalized quantitative analytical technique.     

DLLME-GC法同时测定尿样中4种芳烃类物质尿代产物

建立了分散液相微萃取-气相色谱法同时测定尿样中2,5-己二酮、苯酚、邻甲酚和对硝基酚的方法.确定了最佳色谱条件,优化了分散液相微萃取的萃取剂种类及用量、分散剂种类及用量、pH、萃取时间和加盐量等条件,实现了对尿样中四种有害物质尿代产物的同时提取和测定.在最佳实验条件下,建立4种组分的工作曲线,线性范围为0.02～8.3...     

High-pressure liquid chromatographic analysis of carbofuran and two non-conjugated metabolites in crops as fluorescent dansyl derivatives

Carbofuran, and non-conjugated 3-hydroxycarbofuran and 3-ketocarbofuran were extracted from carrots, corn and potatoes with acetone and partitioned into hexane-methylene chloride. The organic extract was evaporated to a small volume for clean-up on a 2% deactivated Florisil column. All three carbamates were eluted with 15% acetone in hexane. The pesticide residues were hydrolysed to their corresponding phenols with 0.1 M sodium carbonate followed by derivatization with dansyl chloride in acetone. The derivatives were extracted and analysed by high-pressure liquid chromatography with fluorescence detection (excitation, 360 nm; emission, greater than 400 nm). Absolute recoveries for all three compounds were between 50 and 65% for spiked samples by the extraction method used. Detection limits approached 0.01 ppm in the foods studied.     

Determination of biogenic amines as dansyl derivatives in intestinal digesta and feces by reversed phase HPLC

Summary A new method was developed for the determination of fifteen biogenic amines in the intestinal digesta and feces of animal or human origin. The method involves the addition of an internal standard (heptylamine), extraction of the amines, and precipitation of the proteins with perchloric acid. The amines are derivatised with dansyl chloride, separated on a C18 column using gradient elution with 0.2M ammonium acetate at pH 5, water and acetonitrile, and detected with a fluorescence detector. The separation was achieved in a 40 min run. Recoveries ranged from 67 to 110%, the relative standard deviation for intra-assay precision being <5% and the limit of determination 1–5 mg kg⁻¹. The method is specific for biogenic amines in intestinal and fecal samples.