Concentrations Of Ng Research Articles

Ultratrace PFAS Detection Using Amplifying Fluorescent Polymers.

Per- and poly(fluoroalkyl) substances (PFAS) are environmentally persistent pollutants that are of growing concern due to their detrimental effects at ultratrace concentrations (ng·L-1) in human and environmental health. Suitable technologies for on-site ultratrace detection of PFAS do not exist and current methods require complex and specialized equipment, making the monitoring of PFAS in distributed water infrastructures extremely challenging. Herein, we describe amplifying fluorescent polymers (AFPs) that can selectively detect perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) at concentrations of ng·L-1. The AFPs are highly fluorinated and have poly(p-phenylene ethynylene) and polyfluorene backbones bearing pyridine-based selectors that react with acidic PFAS via a proton-transfer reaction. The fluorinated regions within the polymers partition PFAS into polymers, whereas the protonated pyridine units create lower-energy traps for the excitons, and emission from these pyridinium sites results in red-shifting of the fluorescence spectra. The AFPs are evaluated in thin-film and nanoparticle forms and can selectively detect PFAS concentrations of ∼1 ppb and ∼100 ppt, respectively. Both polymer films and nanoparticles are not affected by the type of water, and similar responses to PFAS were found in milliQ water, DI water, and well water. These results demonstrate a promising sensing approach for on-site detection of aqueous PFAS in the ng·L-1 range.

Homogeneous and Heterogeneous Photocatalysis for the Treatment of Pharmaceutical Industry Wastewaters: A Review.

Pharmaceuticals are biologically active compounds used for therapeutical purposes in humans and animals. Pharmaceuticals enter water bodies in various ways and are detected at concentrations of ng L−1–μg L−1. Their presence in the environment, and especially long-term pollution, can cause toxic effects on the aquatic ecosystems. The pharmaceutical industry is one of the main sources introducing these compounds in aquatic systems through the disposal of untreated or partially treated wastewaters produced during the different procedures in the manufacturing process. Pharmaceutical industry wastewaters contain numerous pharmaceutical compounds and other chemicals and are characterized by high levels of total dissolved solids (TDS), biochemical oxygen demand (BOD) and chemical oxygen demand (COD). The toxic and recalcitrant nature of this type of wastewater hinders conventional biological processes, leading to its ineffective treatment. Consequently, there is an urgent demand for the development and application of more efficient methods for the treatment of pharmaceutical industry wastewaters. In this context, advanced oxidation processes (AOPs) have emerged as promising technologies for the treatment of pharmaceutical industry wastewaters through contaminant removal, toxicity reduction as well as biodegradability improvement. Therefore, a comprehensive literature study was conducted to review the recent published works dealing with the application of heterogeneous and homogeneous photocatalysis for pharmaceutical industry wastewater treatment as well as the advances in the field. The efficiency of the studied AOPs to treat the wastewaters is assessed. Special attention is also devoted to the coupling of these processes with other conventional methods. Simultaneously with their efficiency, the cost estimation of individual and integrated processes is discussed. Finally, the advantages and limitations of the processes, as well as their perspectives, are addressed.

Separating dissolved silver from nanoparticulate silver is the key: Improved cloud-point-extraction hyphenated to single particle ICP-MS for comprehensive analysis of silver-based nanoparticles in real environmental samples down to single-digit nm particle sizes

Investigating silver-based nanoparticles (Ag-b-NPs) in environmental samples is challenging with current analytical techniques, owing to their low concentrations (ng L−1) in the presence of high quantities of dissolved Ag(I) species. sp-ICP-MS is a promising technique able to simultaneously determine the concentration and particle sizes of Ag-b-NPs even at concentrations of several ng L−1. However, sp-ICP-MS suffers from the coexistence of dissolved analyte species causing high background signals. These background signals cover particle signals and therefore limit the size detection limit (SDL) in sp-ICP-MS. Ag-b-NPs in environmental samples exhibit diameters of < 20 nm, whereas the current sp-ICP-MS approaches barely reach an SDL as low as 20 nm. Using a surfactant-mediated sample pre-treatment (improved cloud point extraction, iCPE), we were able to separate Ag-b-NPs in aqueous samples from dissolved Ag(I) species and enrich the NPs in the extract. By hyphenating iCPE to sp-ICP-MS, we were able to reach SDL values as low as 4.5 nm, thus paving the way for the successful monitoring of Ag-b-NPs in the environment.

Effects of nonglycosylated and glycosylated prolactin on basal and gonadotropin-stimulated steroidogenesis in chicken ovarian follicles

In galliformes, the circulating isoform of prolactin (PRL) significantly changes during different reproductive states. However, the role of the major isoform (glycosylated PRL [G-PRL]) in ovarian steroidogenesis is unknown. The present study aimed to compare the effects of nonglycosylated (NG-) and G-PRL on basal and gonadotropin-stimulated estradiol (E2) and progesterone (P4) production in granulosa cells or follicular walls of chicken of different size class follicles. In the initial experiment, granulosa cells of preovulatory F3-F1 and prehierarchical 6- to 8-mm follicles were incubated for 24 h with different concentrations of NG- or G-PRL (0, 1, 10, 100, or 1,000 ng/mL). In the subsequent experiments, these categorized granulosa cells and follicular walls of prehierarchical 4–6, 2–4, and <2-mm follicles were incubated for 24 h in the absence and presence of 10-ng/mL FSH or LH, or in combination with different concentrations of NG- or G-PRL (10, 100, or 1,000 ng/mL). We observed that lower levels of NG-PRL induced (P < 0.05) E2 and P4 secretion in granulosa cells of either preovulatory or prehierarchical follicles, but at higher levels, this effect was reduced. In contrast, G-PRL promoted (P < 0.05) basal E2 and P4 secretion in preovulatory granulosa cells but was inhibitory (P < 0.05) in prehierarchical granulosa cells. Results obtained by real-time quantitative PCR (qPCR) demonstrated that these effects were mediated through modulation of the expression of StAR, CYP11A1, CYP19A1, and 3β-HSD. Furthermore, G-PRL was less potent than NG-PRL in inhibiting FSH- or LH-stimulated E2 and P4 production in granulosa cells of preovulatory follicles, whereas NG-PRL enhanced (P < 0.05) but G-PRL reduced (P < 0.05) FSH-induced P4 production in those of prehierarchical follicles. In follicular walls from each group of prehierarchical 4–6, 2–4, and <2-mm follicles, NG- and G-PRL had both stimulatory and inhibitory influences on the actions of FSH on E2 and P4 secretion, but both suppressed (P < 0.05) LH-induced E2 and P4 secretion except for the synergistic effects of LH and G-PRL on P4 secretion by follicular walls of the follicles of 4–6 mm. Taken together, these results suggest that both NG- and G-PRL are biologically active in regulating basal and gonadotropin-stimulated E2 and P4 production in chicken ovarian follicles. However, their effects are different depending on the concentration, the type of gonadotropin (FSH or LH), and the stage of follicle development.

Occurrence of illicit drugs in surface waters in China

Illicit drugs have been recognized as a group of emerging contaminants. In this work, occurrence of common illicit drugs and their metabolites in Chinese surface waters was examined by collecting samples from 49 lakes and 4 major rivers across the country. Among the drugs examined, methamphetamine and ketamine were detected with highest frequencies and concentration levels, consistent with the fact that these are primary drugs of abuse in China. Detection frequencies and concentrations of other drugs were much lower than in European lakes and rivers reported in the literature. In most Chinese surface waters methamphetamine and ketamine were detected at concentrations of several ng L−1 or less, but in some southern lakes and rivers, these two drugs were detected at much higher concentrations (up to several tens ng L−1). Greater occurrence of methamphetamine and ketamine in southern surface waters was attributed to greater abuse and more clandestine production of the two drugs in southern China.

Association of CYP1A2 and CYP2D6 gene polymorphism with therapeutic efficacy of duloxetine on depression in southern region of Fujian

Objective To explore the influence of CYP1A2 and CYP2D6 gene polymorphism on blood concentration, therapeutic efficacy and adverse effects of anti-depression drug duloxetine on depression patients in southern region of Fujian. Methods 82 patients with depression were selected from southern region of FuJian, China, and all participates received duloxetine for two weeks. Blood concentrations of duloxetine were detected by HPLC-MS, and CYP1A2 and CYP2D6 genotypes were determined by sequencing with the amplified PCR products from peripheral blood DNA.The therapeutic efficacy and adverse effects of duloxetine were evaluated by Hamilton depression scale (HAMD) and treatment emergent symptom scale (TESS) respectively. Results Subjects were divided into GG, GA and AA three groups based on CYP1A2*1C genotyping. There was no significant difference in blood concentrations of duloxetine, dose-corrected blood concentrations, the reduction rate of HAMD and the reduction rate of TESS among the three groups. Results were the same with CYP1A2*1F, which were divided into CC, CA and AA three groups. Subjects was divided into CC, CT, TT three groups based on CYP2D6*10 locus genotyping.Blood concentrations of duloxetine were (13.89±3.22)ng·ml-1, (16.08±4.24)ng·ml-1, (17.25±4.62)ng·ml-1 respectively and there was significant difference(F=3.21, P 0.05). Dose-corrected blood concentrations were (304.84±103.76), (368.13±143.49), (444.50±195.58) respectively and there was significant difference(F=4.19, P<0.05), and CC group was significantly lower than TT group(P<0.05). The reduction rate of HAMD were 0.42±0.11, 0.46±0.11, 0.52±0.09 respectively and there was significant difference(F=6.29, P<0.05), and CC and CT group was significantly lower than TT group(P<0.05). The reduction rate of TESS were 1.14±0.66, 1.48±0.69, 1.69±0.69 respectively and there was significant difference(F=3.38, P<0.05). CC group was significantly lower than TT group(P<0.05). Conclusion Among the 3 loci studied, only CYP2D6*10 locus within CYP2D6 gene can affect blood concentration, efficacy and adverse effects of duloxetine, which indicate that CYP2D6 gene polymorphism may contribute to therapeutic efficacy of duloxetine on depression in southern region of Fujian. Key words: Duloxetine; CYP1A2; CYP2D6; Gene polymorphism; Blood concentration

Toxic effects of erythromycin on photosystem I and II in Microcystis aeruginosa

Environmental pollution by antibiotics poses a potential ecological risk to aquatic photosynthetic organisms. In the present study, toxic effects of erythromycin on PSI and PSII were investigated in cyanobacteria culture medium of Microcystis aeruginosa. The activity and electron transport of both photosystems were affected by erythromycin in a concentrationdependent manner. The quantum yield of PSII (YII) was reduced at 0.1 mg L−1 of erythromycin, while the quantum yield of PSI (YI) significantly decreased at concentration of 5–25 mg L−1. The decline of YII was accompanied by an increase of nonregulated energy dissipation (YNO). At 10 mg L−1 of erythromycin, YII decreased by 55%, while YNO increased by 18%. The decrease of YI induced by erythromycin was caused by donor-side limitation of PSI (YND). YND was markedly enhanced with elevated erythromycin concentration. At 10 mg L−1 of erythromycin, YI and YNA (PSI acceptor-side limitation) decreased by 8 and 82%, respectively, while YND rose by 314%. The quantum yield of cyclic electron flow increased significantly at 0.1–1 mg L−1 of erythromycin; it decreased but remained higher than that of the control at 5–25 mg L−1 of erythromycin. The contribution of cyclic electron flow to YI, and to linear electron flow rose significantly with the increasing erythromycin concentration. The maximum values of electron transport rates in PSII and PSI decreased by 71 and 24.3%, respectively, at 25 mg L−1 of erythromycin. Compared with the untreated control, the light saturation of PSII and PSI decreased significantly with increasing erythromycin concentration. We showed that concentrations of erythromycin ≥ 5 mg L−1 could exert acute toxicity to cyanobacteria, whereas the chronic toxicity caused by concentrations of ng or μg L−1 needs further research.

Premature Aging of Cardiovascular/Platelet Function in Polycystic Ovarian Syndrome

ObjectiveThe objective of this study was to compare the impact of aging on nitric oxide (NO) modulation of platelet and vascular function in healthy women and women with polycystic ovary syndrome. Methods and ResultsA case-control study of women ages 18 to 60 years, comparing women with polycystic ovarian syndrome against age-matched healthy controls, was performed. A total of 242 women, of whom 109 had polycystic ovarian syndrome (based on Rotterdam criteria), participated in the study. Women who were pregnant or on clopidogrel were excluded from the study. Inhibition of platelet aggregation by nitric oxide (primary outcome measure), vascular endothelial function, plasma concentrations of NG, NG-dimethyl-L-arginine (ADMA), endothelial progenitor cell count, and high-sensitivity C-reactive protein (markers of endothelial dysfunction and inflammation) were assessed. With increasing age in control women, there was progressive attenuation of platelet responses to NO, impairment of endothelial function, and elevation of ADMA levels (P ≤.001). Irrespective of age, women with polycystic ovarian syndrome exhibited greater impairment of all these parameters (all P <.05, 2-way analysis of variance) and demonstrated these anomalies earlier in life. ConclusionsNormal aging in women is associated with attenuation of NO-based signaling in platelets and blood vessels. In women with polycystic ovarian syndrome, these changes are present from early adult life and may contribute to premature atherogenesis.

Estrogenic activity profiles and risks in surface waters and sediments of the Pearl River system in South China assessed by chemical analysis and in vitro bioassay

Estrogenic activity risks in the Pearl River system (Liuxi River, Zhujiang River and Shijing River) in South China were assessed by combined chemical analysis and recombinant yeast estrogen screen (YES) bioassay for surface waters and sediments collected in both dry and wet seasons. The xenoestrogens 4-tert-octylphenol, 4-nonylphenol and bisphenol A were detected at almost every sampling site at concentrations of several ng L(-1) (ng g(-1)) to tens of μg L(-1) (μg g(-1)) in surface waters (and sediments). The estrogens estrone and 17β-estradiol were also detected in most of the samples with concentrations from several ng L(-1) (ng g(-1)) to tens of ng L(-1) (ng g(-1)) in surface waters (and sediments). However, synthetic estrogens diethylstilbestrol and 17α-ethinylestradiol were only detected at a few sites. The 17β-estradiol equivalents (EEQ) screened by the YES bioassay were in the range of 0.23-324 ng L(-1) in surface waters and from not detected to 101 ng g(-1) in sediments. Shijing River displayed one to two orders of magnitude higher levels for both measured chemical concentrations and estrogenic activities than the Zhujiang River and the Liuxi River. A risk assessment for the surface waters showed high risks for the downstream reaches of the Liuxi River and the upstream to midstream reaches of the Zhujiang River and the Shijing River. Higher estrogenic risks were observed in the wet season than in the dry season for surface waters, probably due to the input of runoff and direct overflow of small urban streams during heavy rain events. Only small variations in estrogenic risk were found for the sediments between the two seasons, suggesting that sediments are a sink for these estrogenic compounds in the rivers.

Trace Element Data for Gold, Iridium and Silver in Seventy Geochemical Reference Materials

New concentrations for Au, Ir and Ag obtained by instrumental neutron activation analysis are presented for seventy geochemical reference materials. Results in agreement with literature values for Au and Ir down to concentrations of a few ng g−1 were obtained. For Au and Ir concentrations above 10 ng g−1, the repeatability of replicate analyses of reference materials was mostly better than 10%. For concentrations between 1 and 10 ng g−1 the RSD for Ir was 10–30%, whereas for Au it was higher and more variable (20–50%). In addition, concentrations for Cd and Hg are presented for some of the same reference materials. The high RSD at relatively high concentrations seen in gold for some RMs (e.g., WMG‐1, WMS‐1) did not exist for Ir and suggests homogeneity for this platinum‐group element at the sub‐sample size used in this study. For the following eight RMs, mostly ultramafic rocks (CHR‐Pt+, OREAS‐13P, OREAS‐14P, PCC‐1, UMT‐1, WMG‐1, WMS‐1, WPR‐1), Ir measurements agreed within ± 10% of mostly certified or recommended concentrations, which ranged from 2 ng g−1 to 6 μg g−1. For the reference material UB‐N, iridium concentration compared favourably to published results obtained by isotope dilution ICP‐MS methods and a previously unrecognised heterogeneity is inferred for Au, Hg and Sb, but not for the other measured elements.

Ion Chromatography Determination of Heavy Metals in Airborne Particulate with Preconcentration and Large Volume Direct Injection

A flow injection analysis system with on-line enrichment was developed for simultaneous determination of trace levels of Cu2+, Ni2+, Zn2+, Co2+, Mn2+, Cd2+, Pb2+ and Fe3+, by high-performance ion chromatography (HPIC) with spectrophotometric detection. It is a highly sensitive and low cost alternative methodology. Ion Pac CS5A was used as the analytical column with eluent composition of sodium nitrate 160 mM and oxalic acid 36 mM. Quantification after post-column reaction with PAR allows detection limits between 0.5 and 5.0 ppb to be attained. The total analysis time is less than 30 min. The proposed procedure was compared with a large volume direct injection method using loop volumes up to 5 mL. Both procedures were applied to the analysis of heavy metals in the PM10 fraction of atmospheric particulate samples. Airborne pollutants such as nickel and cobalt can be quantified in 24 h samples of particulate matter at concentrations of a few ng m−3.

Endogenous Nitric Oxide Synthase Inhibitors in Endothelial Cells, Endothelin-1 Within the Vessel Wall, and Intimal Hyperplasia in Perimenopausal Human Uterine Arteries

The present experiments were designed to investigate the ability to produce nitric oxide, concentrations of N(G)-monomethyl-L-arginine (L-NMMA), and asymmetric N(G), N(G)-dimethyl-L-arginine (ADMA) in endothelial cells, endothelin-1 within the vessel wall, and the degree of intimal hyperplasia (intima/media ratio) in perimenopausal human uterine arteries. According to the tentative classification based on basal cyclic GMP levels, 16 arteries could be grouped into groups I and II consisting of eight each. Net production of the nucleotide was significantly higher in group I than that in group II. Concentration of L-NMMA plus ADMA and endothelin-1 content were significantly higher in group II. All specimens from group I were histologically normal, whereas mild to severe intimal hyperplasia was observed in group II specimens. Although considerable individual variations were detectable in the intima/media ratio, L-NMMA plus ADMA and endothelin-1 (n = 35 each), there were significant and positive correlations between three parameters, indicating that intimal hyperplasia became greater as L-NMMA plus ADMA and endothelin-1 were increased. These results suggest that endogenous nitric oxide synthase inhibitors in endothelial cells and endothelin-1 within the vessel wall are important markers of intimal hyperplasia.

Capsaicin-sensitive afferent sensory nerves in modulating gastric mucosal defense against noxious agents

In the rat stomach, evidence has been provided that capsaicin-sensitive sensory nerves (CSSN) are involved in a local defense mechanism against gastric ulcer. In the present study capsaicin or resiniferatoxin (RTX), a more potent capsaicin analogue, was used to elucidate the role of these sensory nerves in gastric mucosal protection, mucosal permeability, gastric acid secretion and gastrointestinal blood flow in the rat. In the rat stomach and jejunum, intravenous RTX or topical capsaicin or RTX effected a pronounced and long-lasting enhancement of the microcirculation at these sites, measured by laser Doppler flowmetry technique. Introduction of capsaicin into the rat stomach in very low concentrations of ng–μg.mL –1 range protected the gastric mucosa against damage produced by topical acidified aspirin, indomethacin, ethanol or 0.6 N HCl. Resiniferatoxin exhibited acute gastroprotective effect similar to that of capsaicin and exerted marked protective action on the exogenous HCl, or the secretagogue-induced enhancement of the indomethacin injury. The ulcer preventive effect of both agents was not prevented by atropine or cimetidine treatment. Capsaicin given into the stomach in higher desensitizing concentrations of 6.5 mM markedly enhanced the susceptibility of the gastric mucosa and invariably aggravated gastric mucosal damage evoked by later noxious challenge. Such high desensitizing concentrations of capsaicin, however, did not reduce the cytoprotective effect of prostacyclin (PGI 2) or β-carotene. Capsaicin or RTX had an additive protective effect to that of atropine or cimetidine. In rats pretreated with cysteamine to deplete tissue somatostatin, capsaicin protected against the indomethacin-induced mucosal injury. Gastric acid secretion of the pylorus-ligated rats was inhibited with capsaicin or RTX given in low non-desensitizing concentrations, with the inhibition being most marked in the first hour following pylorus-ligation. Low intragastric concentrations of RTX reduced gastric hydrogen ion back-diffusion evoked by topical acidified salicylates. It is concluded that the gastropotective effect of capsaicin-type agents involves primarily an enhancement of the microcirculation effected through local release of mediator peptides from the sensory nerve terminals. A reduction in gastric acidity may contribute to some degree in the gastric protective action of capsaicin-type agents. The vasodilator and gastroprotective effects of capsaicin-type agents do not depend on vagal efferents or sympathetic neurons, involve prostanoids, histaminergic or cholinergic pathways.

Flow-injection sample preparation for organotin speciation analysis of water by capillary gas chromatography-microwave-induced plasma atomic emission spectrometry

A semi-automated flow-injection system was developed for on-line sample preparation for the determination of mono-, di- and tributyl- and phenyltin compounds in water. The procedure is based on the preconcentration of ionic organotin compounds by sorption on bonded silica with octadecyl functional groups followed by on-column ethylation using sodium tetraethylborate. The derivatized species are eluted with 250 μl of methanol, separated by gas chromatography and detected with a microwave-induced plasma atomic emission detector. Aliquots of 25 μl of the eluate are introduced on to a capillary column using the cool injection technique. The solvent is vented off in the liner before the temperature of the latter is raised to release the analytes. A 10–50 ml water sample is sufficient for the analysis and a detection limit of 0.1 ng 1 −1 can be obtained. The developed procedure was applied to the determination of organotin compounds in a number of river water samples which were analysed in parallel using a manual liquid-liquid extraction procedure. The results agreed within 10–15% for concentrations of a few ng 1 −1.

Ambient concentration and precipitation scavenging of atmospheric organic pollutants

Trace organic compounds were measured in air and rainfall at a rural site in Texas. Chlorinated hydrocarbons and phthalic acid esters (PAEs) were present at concentrations of ng m−3 in air and ng L−1 in precipitation. The most abundant compounds measured in air were PAEs > toxaphene > chlordane > hexachlorocyclohexanes (HCHs) > others. In rainfall the concentration order was PAEs > toxaphene > HCHs > DDTs > chlordane >- PCBs > others. An inverse correlation between concentration and rainfall amount was observed for most compounds. A model of precipitation scavenging of these compounds considered both scavenging of gas-phase and particle-bound compounds from the atmosphere. Good agreement was obtained between theoretical and measured concentrations. Results indicate that scavenging of a small amount of particle-bound compound can account for >98% of wet deposition for insoluble organic pollutants. Gas-phase scavenging is important for the more soluble compounds such as HCH.

Direct Determination of Mercury in the Laboratory Atmosphere by Impaction-Electrothermal Atomization Atomic Absorption Spectrometry

Abstract A single stage impaction system connected to an electrothermal atomization atomic absorption spectrometer will allow a direct and near real time determination of mercury in the laboratory atmosphere to be detected. Practical concentrations of low ng m− 3 can be detected, with good precision and linearity of calibration curve. The system detected m− 3 levels of mercury directly and on a near real time in the vicinity of a polarography instrument.

A RADIOIMMUNOASSAY FOR CHOLECYSTOKININ-PANCREOZYMIN

A sensitive and specific radioimmunoassay for cholecystokinin-pancreozymin (C.C.K.-P.Z.) has been developed, using rabbit antisera to crude porcine hormone. Very highly purified porcine C.C.K.-P.Z., labelled with iodine-131, is used as tracer. Separation of free from antibodybound labelled C.C.K.-P.Z. is carried out using a double-antibody procedure. No significant crossreaction is found with gastrin, secretin, or glucagon. The sensitivity of the assay is approximately 5 pg. per ml. of test solution, and this is adequate for measuring physiological levels of C.C.K.-P.Z. in peripheral blood in man. The mean immunoreactive C.C.K.-P.Z. concentration in twenty-five fasting normal subjects was 25·8 pg. per ml. (range <5 to 80). After the ingestion of 1 pint of milk serum C.C.K.-P.Z. rose rapidly, reaching peak concentrations of several ng. per ml. C.C.K.-P.Z. disappeared from the circulation very rapidly, with a plasma half-life in most cases of approximately 5-7 minutes. In ten patients with deficiency of pancreatic exocrine secretion very high fasting levels of serum-C.C.K.-P.Z. were found (mean 8560 pg. per ml.).