Homogeneous liquid-liquid extraction as an alternative sample preparation technique for biomedical analysis.

Liquid-liquid extraction is a widely used technique of sample preparation in biomedical analysis. In spite of the high pre-concentration capacities of liquid-liquid extraction, it suffers from a number of limitations including time and effort consumption, large organic solvent utilization, and poor performance in highly polar analytes. Homogeneous liquid-liquid extraction is an alternative sample preparation technique that overcomes some drawbacks of conventional liquid-liquid extraction, and allows employing greener organic solvents in sample treatment. In homogeneous liquid-liquid extraction, a homogeneous phase is formed between the aqueous sample and the water-miscible extractant, followed by chemically or physically induced phase separation. To form the homogeneous phase, aqueous samples are mixed with water-miscible organic solvents, water-immiscible solvents/cosolvents, surfactants, or smart polymers. Then, phase separation is induced chemically (adding salt, sugar, or buffer) or physically (changing temperature or pH). This mode is rapid, sustainable, and cost-effective in comparison with other sample preparation techniques. Moreover, homogeneous liquid-liquid extraction is more suitable for the extraction of delicate macromolecules such as enzymes, hormones, and proteins and it is more compatible with liquid chromatography with tandem mass spectrometry, which is a vital technique in metabolomics and proteomics. In this review, the principle, types, applications, automation, and technical aspects of homogeneous liquid-liquid extraction are discussed.

Determination of steroid profile in hair by liquid chromatography tandem mass spectrometry.

The simultaneous determination of a large number of steroids (a.k.a. steroid profile) is a powerful tool that provides useful information about the status of steroid hormones. Steroid profile evaluated in matrices such as urine, saliva and plasma provide one-off moment information about the hormonal status and is highly affected by different factors such as circadian rhythm or apprehension to needles. In contrast, the determination of the steroid profile in hair would provide information about the chronic status of the steroid hormones. The objective of the current research was to develop and validate a liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodology for the determination of 11 steroids in hair, including 6 hormones and 5 metabolites. We have optimized different parts of the analytical procedure such as (i) hair shredding, (ii) hair amount, (iii) extraction from hair, (iv) extraction time, (v) required extractions and (vi) analytes preconcentration. MS parameters such as the inclusion of ESI- transitions were also evaluated. The optimization of these parameters was found to be critical to achieve the required sensitivity for the determination of steroids in hair. The method was validated with appropriate linearity in the endogenous range, intra- and inter-assay accuracies and matrix effect between 80% and 120% and intra- and inter-assay precisions below 20% for all analytes. Most of the analytes showed to be stable up to 10 months at room temperature. The suitability of the method was evaluated by obtaining the endogenous concentration range of steroids in 30 healthy volunteers. Results agreed with the scarce data previously reported for some steroids. For others, endogenous concentration ranges in hair were reported for the first time. Additionally, the method was used to compare intraindividual levels of steroids in beard and hair. Results revealed that with the exception of testosterone, beard is a suitable alternative to the hair determination of the steroid profile. In summary, the present strategy to evaluate the steroid profile in hair may be a useful tool with a high potential for a wide range of clinical purposes.

Development of a thin-film solid-phase microextraction (TF-SPME) method coupled to liquid chromatography and tandem mass spectrometry for high-throughput determination of steroid hormones in white sucker fish plasma.

Steroid hormones (SH) play a number of important physiological roles in vertebrates including fish. Changes in SH concentration significantly affect reproduction, differentiation, development, or metabolism. The objective of this study was to develop an in vitro high-throughput thin-film solid-phase microextraction (TF-SPME)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for targeted analysis of endogenous SH (cortisol, testosterone, progesterone, estrone (E1), 17ß-estradiol (E2), and 17α-ethinylestradiol (EE2)) in wild white sucker fish plasma where the concentrations of the analytes are substantially low. A simple TF-SPME method enabled the simultaneous determination of free and total SH concentrations. The use of biocompatible coating allowed direct extraction of these hormones from complex biological samples without prior preparation. The carryover was less than 3%, thereby ensuring reusability of the devices and reproducibility. The results showed that TF-SPME was suitable for the analysis of compounds in the polarity range between 1.28 and 4.31 such as SH at different physicochemical properties. The proposed method was validated according to bioanalytical method validation guidelines. The limit of detection (LOD) and limit of quantification(LOQ) for cortisol, testosterone, progesterone, E1, E2, and EE2 were from 0.006 to 0.150 ng/mL and from 0.020 to 0.500 ng/mL, respectively. The recovery for the method was about 85%, and the accuracy and precision of the method for cortisol, testosterone, and progesterone were ≤ 6.0% and ≤ 11.2%, respectively, whereas those for E1, E2, and EE2 were ≤ 15.0% and ≤ 10.2%, respectively. On the basis of this study, TF-SPME demonstrated several important advantages such as simplicity, sensitivity, and robustness under laboratory conditions. Graphical abstract.

Validation of ultrasonic-assisted switchable solvent liquid phase microextraction for trace determination of hormones and organochlorine pesticides by GC-MS and combination with QuEChERS.

QuEChERS and switchable solvent liquid phase microextraction (SS-LPME) were respectively used as pretreatment and preconcentration tools to allow trace determination of selected organochlorine pesticides and hormones by gas chromatography mass spectrometry (GC-MS). The effects of principal SS-LPME variables and their interactions were evaluated with a Box-Behnken experimental design. The limits of detection obtained by direct GC-MS determination were enhanced by about 33-115 folds under the optimized SS-LPME conditions. The SS-LPME method was applied to tap water, well water, lake water, medical wastewater and tea samples. Satisfactory recovery results were obtained for all but the tea samples using the conventional calibration plot. Matrix matched calibration standards were used to improve the percent recovery of analytes to almost 100% in the tea samples. The combined QuEChERS and SS-LPME method was applied to tomato samples and matrix matching was also used to significantly improve analyte recoveries.

Structure-dependent retention of steroid hormones by common laboratory materials.

The tendency of steroid molecules to adsorb to various materials, particularly plastics, has been known of for decades but has not received widespread attention in the scientific community, and a modern, systematic study is lacking. This adsorption is an important consideration for researchers working with steroid hormones as it could skew the results of various experiments. Here we show that steroids adsorb to various vessels used in experiments, including microcentrifuge tubes, glass vials, and cell culture plates, in a manner that depends on the steroid's molecular structure and on the type of vessel. The lipophilicity of steroids is a strong predictor of the degree of adsorption, with nearly 50 % of the most lipophilic steroid tested, pregnenolone, retained in a high-adsorbing microcentrifuge tube after one hour incubation of an aqueous pregnenolone solution followed by removal of the aqueous solvent. We also show the effects of other factors such as incubation time, centrifugation, and temperature on adsorption, and show that adsorption can be mostly prevented by the presence of serum proteins in steroid solutions and/or by the use of low-adsorbing tubes.

Occurrence, removal and risk assessment of steroid hormones in two wastewater stabilization pond systems in Morogoro, Tanzania.

The present study investigated the occurrence and removal of 10 steroid hormones (4 androgens, 3 progestagens and 3 estrogens) in two WSP systems, Mafisa and Mzumbe in Morogoro, Tanzania. All 10 steroid hormones were detected in the influent of both WSP systems in the dry as well as in the rainy season. The concentrations of steroids in influent wastewater ranged from 0.1 ng/L for 17-OH-pregnenolone to 445 ng/L for estrone and from below limit of detection for 17-OH-pregnenolone to 45 ng/L for estrone in effluent. During dry season, the overall mean ±â€¯standard deviation removal efficiency for the 10 steroids were 70 ±â€¯21% for Mzumbe WSP and 97 ±â€¯3% for Mafisa WSP. During the rainy season the overall mean removal efficiency for all the steroid hormones were 52 ±â€¯32% for Mzumbe WSP and 94 ±â€¯8% for Mafisa WSP. Risk was characterized by calculating the risk quotients (RQs) for fish and humans. 46% of the total RQs calculated were above one, indicating high risk. Low RQs were estimated for androgens and progestagens but the estrogen concentrations measured in the WSP systems and Morogoro River indicated a high risk for fish. However, estrogens appeared not to pose an appreciable risk to human health from water intake and fish consumption. The results indicated that WSP systems are quite effective in removing steroid hormones from wastewater. Thus, low technology systems such as WSP systems are suitable techniques in low income counties due to relatively low costs of building, operating and maintaining these systems.

Combination of in situ metathesis reaction with a novel "magnetic effervescent tablet-assisted ionic liquid dispersive microextraction" for the determination of endogenous steroids in human fluids.

Herein, a novel magnetic effervescence tablet-assisted microextraction coupled to in situ metathesis reaction of ionic liquid (IS-META-ILDM) is presented for the determination of four endogenous steroids in human urine, pregnant women's blood, and fetal umbilical cord blood. The magnetic effervescent tablets, which were composed of Fe3O4 nanoparticles, sodium carbonate (alkaline source), and tartaric acid (acidic source), were used to disperse the extractant and for convenient magnetic separation. After the effervescent reaction, in situ reaction between NH4PF6 and [C6MIM]BF4 was adopted to change hydrophilic ionic liquid to hydrophobic liquid, which could be separated from the aqueous phase. The newly developed method has three obvious advantages: (1) combination of effervescent dispersion and magnetic nanoparticles' retrieval is cost-effective and the dispersion and collection of the extractant can be completed almost simultaneously; (2) as compared to temperature-controlled ionic liquid dispersive microextraction and cold-induced solidified microextraction, this method avoids a heating and cooling process which significantly reduces the extraction time and energy cost; and (3) the combination of adsorption by magnetic nanoparticles with extraction by in situ metathesis reaction easily produces high recoveries for target analytes. The optimized composition of effervescent tablet and experimental parameters are as follows: 0.64 g mixture of sodium carbonate and tartaric acid, 7 mg of Fe3O4 (20 nm) as magnetic sorbents, 40 µL of [C6MIM]BF4 as the extraction solvent, 0.15 g NH4PF6, and 300 µL of elution solvent. Under the optimized conditions, the newly developed method provided high extraction recoveries (90.0-118.5%) and low LODs (0.14-0.17 µg L-1) in urine and blood samples. In total, this IS-META-ILDM method provided high extraction efficiency, fast and convenient separation, and underutilization of any organic solvent, and thus it has great potential for the determination of trace endogenous steroids in complex human fluids. Graphical abstract The newly developed method has three obvious advantages: combination of effervescent dispersion and magnetic nanoparticles' retrieval is cost-effective and the dispersion and collection of the extractant can be completed almost simultaneously. It avoids a heating and cooling process which significantly reduces the extraction time and energy cost and easily produces high recoveries for target analytes.

A novel stress hormone response gene in tadpoles of Xenopus tropicalis.

Previous work identified a transcribed locus, Str. 34945, induced by the frog stress hormone corticosterone (CORT) in Xenopus tropicalis tails. Because thyroid hormone had no influence on its expression, Str. 34945 was dubbed the first "CORT-only" gene known from tadpoles. Here, we examine the genomic annotation for this transcript, hormone specificity, time course of induction, tissue distribution, and developmental expression profile. The location of Str. 34945 on the X. tropicalis genome lies between the genes ush1g (Usher syndrome 1G) and fads6 (fatty acid desaturase 6). A blast search showed that it maps to the same region on the X. laevis genome, but no hits were found in the human genome. Using RNA-seq data and conventional reverse transcriptase PCR and sequencing, we show that Str. 34945 is part of the 3' untranslated region of ush1g. We find that CORT but not aldosterone or thyroid hormone treatment induces Str. 34945 in tadpole tails and that expression of Str. 34945 achieves maximal expression within 12-24 h of CORT treatment. Among tissues, Str. 34945 is induced to the highest degree in tail, with lesser induction in lungs, liver, and heart, and no induction in the brain or kidney. During natural metamorphosis, Str. 34945 expression in tails peaks at metamorphic climax. The role of ush1g in metamorphosis is not understood, but the specificity of its hormone response and its expression in tail make ush1g valuable as a marker of CORT-response gene induction independent of thyroid hormone.

Development of Laboratory Investigations in Disorders of Sex Development.

Scientific knowledge to understand the biological basis of sex development was prompted by the observation of variants different from the 2 most frequent body types, and this became one of the fields first studied by modern pediatric endocrinology. The clinical observation was supported by professionals working in different areas of laboratory sciences which led to the description of adrenal and gonadal steroidogenesis, the enzymes involved, and the different deficiencies. Steroid hormone measurements evolved from colorimetry to radioimmunoassay (RIA) and automated immunoassays, although gas and liquid chromatography coupled to mass spectrometry are now the gold standard techniques for steroid measurements. Peptide hormones and growth factors were purified, and their measurement evolved from RIA to automated immunoassays. Hormone action mechanisms were described, and their specific receptors were characterized and assayed in experimental materials and in patient tissues and cell cultures. The discovery of the genetic basis for variant sex developments began with the description of the sex chromosomes. Molecular technology allowed cloning of genes coding for the different proteins involved in sex determination and development. Experimental animal models aided in verifying the roles of proteins and also suggested new genes to be investigated. New candidate genes continue to be described based on experimental models and on next-generation sequencing of patient DNAs.

Bioprocessing for elimination antibiotics and hormones from swine wastewater.

Antibiotics and hormones in swine wastewater have become a critical concern worldwide due to the severe threats to human health and the eco-environment. Removal of most detectable antibiotics and hormones, such as sulfonamides (SAs), SMs, tetracyclines (TCs), macrolides, and estrogenic hormones from swine wastewater utilizing various biological processes were summarized and compared. In biological processes, biosorption and biodegradation are the two major removal mechanisms for antibiotics and hormones. The residuals in treated effluents and sludge of conventional activated sludge and anaerobic digestion processes can still pose risks to the surrounding environment, and the anaerobic processes' removal efficiencies were inferior to those of aerobic processes. In contrast, membrane bioreactors (MBRs), constructed wetlands (CWs) and modified processes performed better because of their higher biodegradation of toxicants. Process modification on activated sludge, anaerobic digestion and conventional MBRs could also enhance the performance (e.g. removing up to 98% SMs, 88.9% TCs, and 99.6% hormones from wastewater). The hybrid process combining MBRs with biological or physical technology also led to better removal efficiency. As such, modified conventional biological processes, advanced biological technologies and MBR hybrid systems are considered as a promising technology for removing toxicants from swine wastewater.

Occurrence and removal of pharmaceuticals, hormones, personal care products, and endocrine disrupters in a full-scale water reclamation plant.

This study provided the first comprehensive data on the occurrence and removal of twenty-five target emerging contaminants (ECs) in a full-scale water reclamation plant (WRP) in the Southeast Asian region. Nineteen out of the twenty-five ECs were ubiquitously detected in raw influent samples. Concentrations of the detected ECs in raw influent samples ranged substantially from 44.3 to 124,966ng/L, depending upon the compound and sampling date. The elimination of ECs in full-scale conventional activated sludge (CAS) and membrane bioreactor (MBR) systems at a local WRP was evaluated and compared. Several ECs, such as acetaminophen, atenolol, fenoprofen, indomethacin, ibuprofen, and oxybenzone, exhibited excellent removal efficiencies (>90%) in biological wastewater treatment processes, while some of the investigated compounds (carbamazepine, crotamiton, diclofenac, and iopamidol) appeared to be persistent in the both CAS and MBR systems. Field-based monitoring results showed that MBR outperformed CAS in the elimination of most target ECs. The relationship between molecular characteristics of ECs (i.e. physicochemical properties and structural features) and their removal efficiencies during biological wastewater treatment was also elucidated. Excellent removal efficiencies (>90%) were often noted for ECs with the sole presence of electron donating groups (i.e. phenolic [OH], amine [NH2], methoxy [OCH3], phenoxy [OC6H5], or alkyl groups). Conversely, ECs with the absence of electron donating groups or the predominance of strong electron withdrawing groups (e.g. halogenated, carbonyl, carboxyl, and sulfonamide) tended to show poor removal efficiencies (<30%) in biological wastewater treatment processes.

A "Love" Dart Allohormone Identified in the Mucous Glands of Hermaphroditic Land Snails.

Animals have evolved many ways to enhance their own reproductive success. One bizarre sexual ritual is the "love" dart shooting of helicid snails, which has courted many theories regarding its precise function. Acting as a hypodermic needle, the dart transfers an allohormone that increases paternity success. Its precise physiological mechanism of action within the recipient snail is to close off the entrance to the sperm digestion organ via a contraction of the copulatory canal, thereby delaying the digestion of most donated sperm. In this study, we used the common garden snailCornu aspersumto identify the allohormone that is responsible for this physiological change in the female system of this simultaneous hermaphrodite. The love dart allohormone (LDA) was isolated from extracts derived from mucous glands that coat the dart before it is stabbed through the partner's body wall. We isolated LDA from extracts using bioassay-guided contractility measurement of the copulatory canal. LDA is encoded within a 235-amino acid precursor protein containing multiple cleavage sites that, when cleaved, releases multiple bioactive peptides. Synthetic LDA also stimulated copulatory canal contractility. Combined with our finding that the protein amino acid sequence resembles previously described molluscan buccalin precursors, this indicates that LDA is partially conserved in helicid snails and less in other molluscan species. In summary, our study provides the full identification of an allohormone that is hypodermically injected via a love dart. More importantly, our findings have important consequences for understanding reproductive biology and the evolution of alternative reproductive strategies.

Adsorption Removal of Environmental Hormones of Dimethyl Phthalate Using Novel Magnetic Adsorbent.

Magnetic polyvinyl alcohol adsorbent M-PVAL was employed to remove and concentrate dimethyl phthalate DMP. The M-PVAL was prepared after sequential syntheses of magnetic Fe3O4 (M) and polyvinyl acetate (M-PVAC). The saturated magnetizations of M, M-PVAC, and M-PVAL are 57.2, 26.0, and 43.2 emu g(-1) with superparamagnetism, respectively. The average size of M-PVAL by number is 0.75 µm in micro size. Adsorption experiments include three cases: (1) adjustment of initial pH (pH0) of solution to 5, (2) no adjustment of pH0 with value in 6.04-6.64, and (3) adjusted pH0 = 7. The corresponding saturated amounts of adsorption of unimolecular layer of Langmuir isotherm are 4.01, 5.21, and 4.22 mg g(-1), respectively. Values of heterogeneity factor of Freundlich isotherm are 2.59, 2.19, and 2.59 which are greater than 1, revealing the favorable adsorption of DMP/M-PVAL system. Values of adsorption activation energy per mole of Dubinin-Radushkevich isotherm are, respectively, of low values of 7.04, 6.48, and 7.19 kJ mol(-1), indicating the natural occurring of the adsorption process studied. The tiny size of adsorbent makes the adsorption take place easily while its superparamagnetism is beneficial for the separation and recovery of micro adsorbent from liquid by applying magnetic field after completion of adsorption.

Seasonal patterns of hormones, macroparasites, and microparasites in wild African ungulates: the interplay among stress, reproduction, and disease.

Sex hormones, reproductive status, and pathogen load all affect stress. Together with stress, these factors can modulate the immune system and affect disease incidence. Thus, it is important to concurrently measure these factors, along with their seasonal fluctuations, to better understand their complex interactions. Using steroid hormone metabolites from fecal samples, we examined seasonal correlations among zebra and springbok stress, reproduction, gastrointestinal (GI) parasite infections, and anthrax infection signatures in zebra and springbok in Etosha National Park (ENP), Namibia, and found strong seasonal effects. Infection intensities of all three GI macroparasites examined (strongyle helminths, Strongyloides helminths, and Eimeria coccidia) were highest in the wet season, concurrent with the timing of anthrax outbreaks. Parasites also declined with increased acquired immune responses. We found hormonal evidence that both mares and ewes are overwhelmingly seasonal breeders in ENP, and that reproductive hormones are correlated with immunosuppression and higher susceptibility to GI parasite infections. Stress hormones largely peak in the dry season, particularly in zebra, when parasite infection intensities are lowest, and are most strongly correlated with host mid-gestation rather than with parasite infection intensity. Given the evidence that GI parasites can cause host pathology, immunomodulation, and immunosuppression, their persistence in ENP hosts without inducing chronic stress responses supports the hypothesis that hosts are tolerant of their parasites. Such tolerance would help to explain the ubiquity of these organisms in ENP herbivores, even in the face of their potential immunomodulatory trade-offs with anti-anthrax immunity.

Electrochemical biosensors for hormone analyses.

Electrochemical biosensors have a unique place in determination of hormones due to simplicity, sensitivity, portability and ease of operation. Unlike chromatographic techniques, electrochemical techniques used do not require pre-treatment. Electrochemical biosensors are based on amperometric, potentiometric, impedimetric, and conductometric principle. Amperometric technique is a commonly used one. Although electrochemical biosensors offer a great selectivity and sensitivity for early clinical analysis, the poor reproducible results, difficult regeneration steps remain primary challenges to the commercialization of these biosensors. This review summarizes electrochemical (amperometric, potentiometric, impedimetric and conductometric) biosensors for hormone detection for the first time in the literature. After a brief description of the hormones, the immobilization steps and analytical performance of these biosensors are summarized. Linear ranges, LODs, reproducibilities, regenerations of developed biosensors are compared. Future outlooks in this area are also discussed.

Study of a large scale powdered activated carbon pilot: Removals of a wide range of emerging and priority micropollutants from wastewater treatment plant effluents.

The efficacy of a fluidized powdered activated carbon (PAC) pilot (CarboPlus(®)) was studied in both nominal (total nitrification + post denitrification) and degraded (partial nitrification + no denitrification) configuration of the Seine Centre WWTP (Colombes, France). In addition to conventional wastewater parameters 54 pharmaceuticals and hormones (PhPHs) and 59 other emerging pollutants were monitored in influents and effluents of the pilot. Thus, the impacts of the WWTP configuration, the process operation and the physico-chemical properties of the studied compounds were assessed in this article. Among the 26 PhPHs quantified in nominal WWTP configuration influents, 8 have high dissolved concentrations (>100 ng/L), 11 have an intermediary concentration (10-100 ng/L) and 7 are quantified below 10 ng/L. Sulfamethoxazole is predominant (about 30% of the sum of the PhPHs). Overall, 6 PhPHs are poorly to moderately removed (<60%), such as ibuprofen, paracetamol or estrone, while 9 are very well removed (>80%), i.e. beta blockers, carbamazepine or trimethoprim, and 11 are well eliminated (60-80%), i.e. diclofenac, naproxen or sulfamethoxazole. In degraded WWTP configuration, higher levels of organic matter and higher concentrations of most pollutants are observed. Consequently, most PhPHs are substantially less removed in percentages but the removed flux is higher. Thus, the PAC dose required to achieve a given removal percentage is higher in degraded WWTP configuration. For the other micropollutants (34 quantified), artificial sweeteners and phthalates are found at particularly high concentrations in degraded WWTP configuration influents, up to µg/L range. Only pesticides, bisphenol A and parabens are largely eliminated (50-95%), while perfluorinated acids, PAHs, triclosan and sweeteners are not or weakly removed (<50%). The remaining compounds exhibit a very variable fate from campaign to campaign. The fresh PAC dose was identified as the most influencing operation parameter and is strongly correlated to performances. Charge and hydrophobicity of compounds have been recognized as crucial for the micropollutant adsorption on PAC, as well as the molecular weight. Finally, a PAC dose of 10 mg/L allows an average removal of 72-80% of the sum of the PhPHs in nominal WWTP configuration. The comparaison of the results with those from the scarce other studies tends to indicate that an extrapolation of them to different PAC processes and to other WWTPs could be possible and relevant, taking into account the differences of water quality from WWTP to WWTP.

Removal of PPCPs from the sludge supernatant in a one stage nitritation/anammox process.

Pharmaceutical and personal care products (PPCPs) are extensively used and can therefore find their way into surface, groundwater and municipal and industrial effluents. In this work, the occurrence, fate and removal mechanisms of 19 selected PPCPs was investigated in an 'ELiminación Autótrofa de Nitrógeno' (ELAN) reactor of 200 L. In this configuration, ammonium oxidation to nitrite and the anoxic ammonium oxidation (anammox)processes occur simultaneously in a single-stage reactor under oxygen limited conditions. The ELAN process achieved high removal (>80%) of the studied hormones, naproxen, ibuprofen, bisphenol A and celestolide, while it was not effective in the removal of carbamazepine (<7%), diazepam (<7%) and fluoxetine (<30%). Biodegradation was the dominant removal mechanism, while sorption was only observed for musk fragrances, fluoxetine and triclosan. The sorption was strongly dependent on the granule size, with smaller granules facilitating the sorption of the target compounds. Increased hydraulic retention time enhanced the intramolecular diffusion of the PPCPs into the granules, and thus increased the solid phase concentration. The increase of nitritation rate favored the removal of ibuprofen, bisphenol A and triclosan, while the removal of erythromycin was strongly correlated to the anammox reaction rate.

Evaluation of mesoporous silicas functionalized with C18 groups as stationary phases for the solid-phase extraction of steroid hormones in milk.

In this work, two mesoporous silicas functionalized with C18 groups (SM-C18 and SBA-15-C18) have been synthesized for their evaluation as stationary phases in SPE for the extraction and preconcentration of seven steroid hormones (estrone, estradiol, estriol, ethinyl estradiol, diethylstilbestrol, testosterone, and progesterone ) from milk. The characterization of both materials by diverse techniques such as transmission electron microscopy, SEM, thermogravimetric analysis, X-ray diffraction, and adsorption-desorption isotherms showed that the mesoporous silicas had a high surface area, high pore volume, and a homogeneous distribution of the pores and that both silicas presented a similar degree of functionalization. An analytical methodology for the simultaneous separation of the seven selected steroids by HPLC-DAD was developed. Both silicas were evaluated as stationary phases in SPE for the extraction of the steroid hormones from milk. This HPLC-DAD method was applied to the analysis of all extracts obtained in the SPE experiments, showing that from the two synthesized mesoporus silicas, SBA-15-C18 silica enabled the extraction of the seven compounds with recoveries between 88 and 108% for all except for estriol, for which a recovery of 62% was obtained. The analytical characteristics of this methodology were evaluated, showing good precision and linearity (R2 > 0.994) for all analytes. The comparison of the results obtained with this silica and those obtained with commercial C18 particles and with some other commercial cartridges usually employed in the extraction of steroids showed that SBA-15-C18 silica was able to extract the seven steroids with higher recovery values.

Quantitative determination of 26 steroids in eggs from various species using liquid chromatography-triple quadrupole-mass spectrometry.

A method for analyzing 26 types of steroids in egg matrix was developed. The method used liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) in electrospray ionization mode (ESI). The procedure involved extraction with acetonitrile and removal of phospholipids by zinc chloride (ZnCl2) followed by SPE cleanup with a Plexa cartridge. The effect of ZnCl2 on phospholipid removal was directly observed using the post column infusion procedure. The SPE washing and elution conditions were optimized using a shallow gradient procedure. The free and conjugated steroids forms were determined using enzyme hydrolysis. The developed method resulted in satisfactory precision (RSD≤15%), and the limits of quantification were between 0.05 and 25 ng/g depending on the steroid types. The recoveries ranged from 63.2% to 121.5%. Finally, the developed method was successfully applied to compare the steroids in eggs from different species (i.e., hen, duck, quail and pigeon eggs) or different raising system (i.e., normal vs. organic eggs). The steroids can be clearly clustered according to species and raising system. The hierarchical clustering analysis indicated similarity of the steroids among the species. The developed method is sensitive and useful for detection and quantification of steroids in eggs and can be used for residue control programs. In addition, the observed steroid content will provide a fundamental reference for food risk assessment analysis.

Enrichment of steroid hormones in water with porous and hydrophobic polymer-based SPE followed by HPLC-UV determination.

There have been great concerns about the persistence of steroid hormones in surface water. Since the concentrations of these compounds in water samples are usually at a trace level, the efficient enrichment of steroid hormones is vital for further analysis. In this work, a porous and hydrophobic polymer was synthesized and characterized. The composition of solvent used as porogen in the synthetic process was shown to have an effect on the morphology of the polymer, which was successfully used as an SPE sorbent for simultaneously enriching steroid hormones in surface water samples. The recoveries of the steroid hormones on the custom-made polymer ranged from 93.4 to 106.2%, whereas those on commercialized ENVI-18, LC-18, and Oasis HLB ranged from 54.8 to 104.9, 66 to 93.6, and 77.2 to 106%, respectively. Five types of steroid hormones were simultaneously measured using HPLC-UV after they were enriched by the custom-made sorbent. Based on these findings, the SPE-HPLC method was developed. The LODs of this method for estriol, estradiol, estrone, androstenedione, progesterone were 0.07, 0.43, 0.61, 0.27, and 0.42 µg/L, respectively, while precision and reproducibility RSDs were <6.40 and 7.49%, respectively.