Negative Chemical Ionization Mass Spectrometry Research Articles

Development of Quantitative Chemical Ionization Using Gas Chromatography/Mass Spectrometry and Gas Chromatography/Tandem Mass Spectrometry for Ambient Nitro- and Oxy-PAHs and Its Applications

The concentration of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere has been continually monitored since their toxicity became known, whereas nitro-PAHs (NPAHs) and oxy-PAHs (OPAHs), which are derivatives of PAHs by primary emissions or secondary formations in the atmosphere, have gained attention more recently. In this study, a method for the quantification of 18 NPAH and OPAH congeners in the atmosphere based on combined applications of gas chromatography coupled with chemical ionization mass spectrometry is presented. A high sensitivity and selectivity for the quantification of individual NPAH and OPAH congeners without sample preparations from the extract of aerosol samples were achieved using negative chemical ionization (NCI/MS) or positive chemical ionization tandem mass spectrometry (PCI-MS/MS). This analytical method was validated and applied to the aerosol samples collected from three regions in Northeast Asia-namely, Noto, Seoul, and Ulaanbaatar-from 15 December 2020 to 17 January 2021. The ranges of the method detection limits (MDLs) of the NPAHs and OPAHs for the analytical method were from 0.272 to 3.494 pg/m3 and 0.977 to 13.345 pg/m3, respectively. Among the three regions, Ulaanbaatar had the highest total mean concentration of NPAHs and OPAHs at 313.803 ± 176.349 ng/m3. The contribution of individual NPAHs and OPAHs in the total concentration differed according to the regional emission characteristics. As a result of the aerosol samples when the developed method was applied, the concentrations of NPAHs and OPAHs were quantified in the ranges of 0.016~3.659 ng/m3 and 0.002~201.704 ng/m3, respectively. It was concluded that the method could be utilized for the quantification of NPAHs and OPAHs over a wide concentration range.

Association between serum concentrations of perfluoroalkyl substances and global DNA methylation levels in peripheral blood leukocytes of Japanese women: A cross-sectional study

Global DNA methylation levels in peripheral blood leukocytes can be a biomarker for cancer risk; however, levels can be changed by various factors such as environmental pollutants. We investigated the association between serum concentrations of perfluoroalkyl substances (PFASs) and global DNA methylation levels of leukocytes in a cross-sectional study using the control group of a Japanese breast cancer case-control study [397 women with a mean age of 54.1 (SD 10.1) years]. Importantly, our analysis distinguished branched PFAS isomers as different from linear isomers. The serum concentrations of 20 PFASs were measured by in-port arylation gas-chromatography negative chemical ionization mass spectrometry. Global DNA methylation levels in peripheral blood leukocytes were measured using a luminometric methylation assay. Associations between log10-transformed serum PFAS concentrations and global DNA methylation levels were evaluated by regression coefficients in multivariable robust linear regression analyses. Serum concentrations of 13 PFASs were significantly associated with increased global DNA methylation levels in leukocytes. Global DNA methylation was significantly increased by 1.45 %–3.96 % per log10-unit increase of serum PFAS concentration. Our results indicate that exposure to PFASs may increase global DNA methylation levels in peripheral blood leukocytes of Japanese women.

Development and validation of a method for the analysis of halophenols and haloanisoles in cork bark macerates by stir bar sorptive extraction heart-cutting two-dimensional gas chromatography negative chemical ionization mass spectrometry

A method has been developed for the quantitative determination in cork bark macerates of 7 halophenols and 5 haloanisoles with demonstrated or suspected contribution to the cork taint off-flavour. Macerates were extracted with stirbar (20 mm polydimethylsiloxane-coated) sorptive extraction under optimized conditions (pH 3.5, 20% NaCl and 60 min). The bars were analysed by automated thermal desorption, heart-cutting two-dimensional gas chromatography and negative chemical ionization-mass spectrometry. Matrix effects were compensated for by a “matrix matched” calibration curve. Limits of detection were in the range 0.03-0.24 ng L−1, below the corresponding odor thresholds. Linearity (0.983 ≤ R2 ≤ 0.998), intra- and inter-day precision (5.4-14.3%) and accuracy (89–126%) were satisfactory. The analysis of 48 natural cork bark samples affected/not-affected bya cryptogamic disease (yellow spot) revealed compositional differences in 2,4,6-trichloroanisole (2,4,6-TCA), 2,4,6-trichlorophenol (2,4,6-TCP) and also in 2,6-dibromophenol, 2,3,4- and 2,4,5-TCP, 2,3,4-TCA and 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP). In addition, the contents of 2,4,6-TCP and 2,4,6-TCA, and 2,3,4,6-TeCP and some TCPs presented strong linear correlations.

Urine dicarboxylic acids are metabolic biomarkers of early Alzheimer’s disease

AbstractBackgroundWe previously identified urine dicarboxylic acids (DCA) of carbon length 4‐9 as candidate biomarkers of probable Alzheimer’s disease (AD) and energy dysregulation, and found their levels correlated with hippocampal volume. Our aim was to evaluate these initial findings in a second cohort.MethodStudy participants (> 65 years) were classified clinically as cognitively healthy (CH, n=188) or with probable AD (n=66) based on Uniform Data System‐3 of the National Alzheimer’s Coordinating Center criteria. Cerebrospinal fluid (CSF) amyloid ß42 (A) and phospho‐ tau (T) levels were measured by validated immunoassay. Urine was collected in a “spot” sample after a 12 h overnight fast; target DCAs were detected using gas chromatography coupled with negative ion chemical ionization mass spectrometry and each DCA was normalized to deuterated internal standards and to a percent of total fatty acids.ResultThe mean of short‐chain DCA’s (C4‐C5) were higher in CH (44.38% ±17.79) compared to AD individuals (34.79% ±12.39) (p=0.0002), while the long‐chain DCA’s (C7‐C9) were lower for CH (34.70% ±16.88) when compared to AD individuals (45.22% ±15.11) (p<0.0001). DCA levels in the subset of CH participants with A+/T+ were in a transition to the levels of the AD group and C4‐C5 and C7‐C9 differed from those with A‐/T‐ biomarkers (p=0.0001). Combining results into a ratio of short‐ to long‐chain DCAs distinguished the A‐/T‐ (2.330 ±2.144) from the A+/T+ group (1.178 ±0.946); p<0.0001. ROC curve of the DCA ratio between CH‐NAT and AD is 82%. Study participant clinical and DCA groups were not significantly correlated with the common confounders of age, sex, education or ApoE genotype.ConclusionOur data extends our initial finding that urine DCA measures have potential as biomarkers of AD pathology, including for cognitively healthy individuals who are positive for CSF AT biomarkers. We propose that measurement of urine DCAs provides a new approach to screen for metabolic fluctuations in early AD and to monitor the effect of novel therapies in clinical trials. While studies are needed, including with other populations, varied clinical classifications, simplified chemistry, this data supports DCA biomarkers for widespread screening since the necessary urine sample is available from everyone.

Effect of fasting status and other pre-analytical variables on quantitation of long-chain fatty acids in red blood cells

Long-chain fatty acids (LCFAs), including omega-3 and omega-6 fatty acids, play essential roles in health maintenance and outcomes. Insufficient intake or the inability to absorb LCFAs from the diet can cause a number of health problems. Evaluation of fatty acid profiles in plasma, serum or red blood cells (RBCs) is routinely used to monitor patients at risk of developing deficiency. Quantitation of LCFAs in RBCs offers advantages over serum/plasma due to low intra-individual variability. Fatty acid composition in RBCs also reflects long-term dietary intake, providing additional information about the patient's nutritional status. However, the literature does not currently address the impact of pre-analytical factors (conditions of RBC collection, sample handling and short-term storage) on LCFA measurements. This study evaluated the effect of several anticoagulants, interferents, different storage conditions and fasting status on quantitation of the twenty-one most abundant LCFAs in RBCs by gas chromatography negative chemical ionization-mass spectrometry (GCNCI-MS). LCFA results were assessed quantitatively (nmol/mL) or as a percent of total. Most common tube types (containing citrate, sodium heparin or EDTA) were all appropriate for blood collection. Whole blood and lysed RBCs were stable at least 24 h at room temperature and up to 7 days refrigerated. Lysed RBCs were also stable for up to three freeze/thaw cycles. The presence of icterus or lipemia did not affect results. LCFAs concentrations in RBCs did not change ~4 h after high-fat intake when the lipid concentration in circulation reaches a peak, while plasma levels of most fatty acids increased up to 40% in response. In summary, RBCs are a reliable sample type for LCFA quantitation in the clinical laboratory. In contrast to plasma or serum, RBCs isolated from non-fasting, hemolyzed or lipemic whole blood specimens are all acceptable for testing. Therefore, RBCs might be a preferable sample type for evaluation of nutritional status of young pediatric patients and in patients with conditions associated with hemolytic anemia or hyperlipidemia.

Feline urinary F2-isoprostanes measured by enzyme-linked immunoassay and gas chromatography-mass spectroscopy are poorly correlated.

15-F2T-isoprostanes are byproducts of lipid peroxidation and were determined to be the best marker of oxidative injury in a rodent model of oxidative stress. A previous study compared methods for measurement of urinary F2-isoprostanes (gas chromatography and negative ion chemical ionization-mass spectrometry, GC-NICI-MS; and ELISA) and found poor agreement in dogs, horses, and cows. Surprisingly, fair agreement between these methods was identified in a small population of cats. We evaluated the agreement between GC-NICI-MS and ELISA of urinary F2-isoprostanes in the urine of 50 mature cats ranging from healthy to systemically ill. All urine samples had detectable levels of F2-isoprostanes by both methods. Significant proportional bias and poor agreement were identified between the 2 methods (ρ = 0.364, p = 0.009) for all cats, and in subgroup analysis based on health status. The concentration of urinary F2-isoprostanes was significantly lower in systemically ill cats compared to healthy cats when measured by ELISA (p = 0.002) but not by GC-NICI-MS (p = 0.068). Our results indicate that GC-NICI-MS and ELISA have poor agreement when measuring urinary F2-isoprostanes in cats.

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.

Study of the occurrence and multi-pathway health risk assessment of regulated and unregulated disinfection by-products in drinking and swimming pool waters of Mediterranean cities

The occurrence of a wide variety of regulated (four trihalomethanes (THM(4)), five haloacetic acids (HAA(5))) and unregulated (haloacetonitriles (HANs), halogenated ketones, chloropicrin, carbon tetrachloride, and other haloacetic acids) disinfection by-products (DBPs) was studied, in two hundred twenty-six finished drinking water samples collected in Barcelona (Spain, between 2008 and 2009), Athens (Greece, 2009–2010), Heraklion (Greece, 2009–2010), Nicosia (Cyprus, 2012–2013), and Limassol (Cyprus, 2011). The samples were analyzed by using liquid-liquid extraction, gas chromatography coupled with an electron capture detector or negative chemical ionization mass spectrometry. In addition, fourteen swimming pool water samples (from Heraklion and Athens) were also investigated regarding their DBPs content. The studied DBPs were determined concurrently with pH, total organic carbon (TOC), and bromide. Spearman's statistical analysis has shown statistically significant (p < 0.001) weak correlations between TOC, THM(4), HANs and HAA(5) but a strong correlation between THM(4) and HANs. Principal component analysis (PCA) on THM(4), HANs and HAA(5) provided a clear differentiation between the examined drinking waters, on the basis of their DBPs content. In the drinking water of coastal cities, the brominated DBPs dominated over the chlorinated ones, due to the higher bromide concentrations occurring in the corresponding raw waters. Lifetime cancer risk and hazard quotient by exposure to four THMs, dichlorocetic acid and trichloroacetic acid in drinking water and indoor swimming pools through multiple pathways were estimated. Total cancer unit risks in drinking water for Nicosia, Barcelona, Limassol and Athens exceeded in most cases the US EPA's regulatory threshold (1.0E-06). The total lifetime cancer risk evaluated for the studied indoor swimming pools was above the US EPA's negligible level for male, female, and junior swimmers.

Characterization of synthetic single-chain CP standard materials – Removal of interfering side products

The photolytic chlorination of n-alkanes in presence of sulfuryl chloride (SO2Cl2) was explored to produce new standard materials. Five mixtures of chlorinated tetradecanes were synthesized with chlorination degrees (mCl,EA) varying from 43.7% to 59.4% (m/m) based on elemental analysis. Chlorine-enhanced negative chemical ionization mass spectrometry (CE–NCI–MS) forcing the formation of chloride-adduct ions [M+Cl]- was applied to characterize these materials which all contained tetra-to deca-chlorinated paraffins. Deconvolution of respective mass spectra revealed the presence of chlorinated olefins (COs). CO levels were highest in materials, which were exposed longest. All synthesized materials also contained two classes of polar impurities, tentatively assigned as sulfite- and sulfate-diesters with molecular formulas of C14H28-xO3SClx (x = 1–4) and C14H28-xO4SClx (x = 3–6), respectively. MS data were in accordance with the proposed structures but further work is needed to deduce their constitutions. These compounds are thermolabile and were not detected with GC-MS methods. We could remove these sulfur-containing impurities from the CPs with normal-phase liquid chromatography. In conclusion, single-chain CP materials were synthesized via chlorination of n-alkanes with sulfuryl chloride, but these materials contained reactive side products which should be removed to gain non-reactive and stable CP materials suitable as standards and for fate and toxicity studies.

Levels of Octachlorostyrene in Mothers' Milk and Potential Exposure Among Infants in Sendai City, Japan 2012.

Persistent organic pollutants can accumulate inside the human body, including in mothers’ milk, which may affect infant development. This cross-sectional study aimed to examine selected persistent organic pollutants in the milk of 100 mothers in Sendai city, Miyagi Prefecture, Japan. We used gas-chromatography-electron capture negative chemical ionization-mass spectrometry to check for octachlorostyrene, dechlorane (Dec) plus, Dec 602, Dec 603, and Dec 604. Octachlorostyrene was detected in 86 samples at more than the method detection limit (84 pg g-lipid−1) but no dechloranes were above the method detection limit (1 ng mL−1 for dechlorane plus, Dec 602, and Dec 603; 20 ng mL−1 for Dec 604). The mean octachlorostyrene concentration was 461 pg g-lipid−1, the median was 337 pg g-lipid−1, and the standard deviation 450 pg g-lipid−1. No baseline characteristics were associated with octachlorostyrene level except for mother’s occupation (stay-at-home mother, 353 ± 327 pg g-lipid−1; others, 531 ± 509 pg g-lipid−1). Octachlorostyrene was also significantly negatively correlated with lipid content (r = −0.35, p = 0.0004). However, the maximum intake of octachlorostyrene among infants in this study (3.5 ng/kg/day) was under the acceptable daily intake (30 ng/kg/day, derived from 12−month study in rats), and is therefore unlikely to pose a health risk.

Analysis of Perfluorooctanesulfonate Isomers and Other Perfluorinated Alkyl Acids in Serum by In-Port Arylation Gas Chromatography Negative Chemical Ionization–Mass Spectrometry

Perfluorooctanesulfonate (PFOS) is a common environmental pollutant and has been detected in various environmental media. Several major isomers have been identified, and their profiles provide important signatures from the source of contamination. Gas chromatography has a significant resolving power for the isomers. However, methods for derivatizing sulfonates for a sensitive analysis are limited. In this study, in-port derivatization with diaryl iodonium salts into aryl sulfonates was used. A technical mixture of PFOS was separated on gas chromatography to afford 11 isomers. In electron-capture negative ionization, the PFOS derivatives form specific fragmented anions (sulfinate anions). The derivatization was also applied to other per- or polyfluoroalkyl acids (PFASs; 13 perfluoroalkyl carboxylic acids and 10 sulfonates). Analysis of human serum samples was achieved with as little as 50 μL of sample and indicated the presence of PFOS isomers and PFASs. The detection limits of PFOS isomers were 0.02–0.09 ng mL–¹ with sufficient recoveries (85%–98%), and those for other PFASs ranged from 0.01–1 ng mL–¹ (recoveries, 80%–100%), which are suitable for the analysis of human serum samples.

Anverenes B⁻E, New Polyhalogenated Monoterpenes from the Antarctic Red Alga Plocamium cartilagineum.

The subtidal red alga Plocamium cartilagineum was collected from the Western Antarctic Peninsula during the 2011 and 2017 austral summers. Bulk collections from specific sites corresponded to chemogroups identified by Young et al. in 2013. One of the chemogroups yielded several known acyclic halogenated monoterpenes (2–5) as well as undescribed compounds of the same class, anverenes B–D (6–8). Examination of another chemogroup yielded an undescribed cyclic halogenated monoterpene anverene E (9) as its major secondary metabolite. Elucidation of structures was achieved through one-dimensional (1D) and 2D nuclear magnetic resonance (NMR) spectroscopy and negative chemical ionization mass spectrometry. Compounds 1–9 show moderate cytotoxicity against cervical cancer (HeLa) cells.

Eddy flux measurements of sulfur dioxide deposition to the sea surface

Abstract. Deposition to the sea surface is a major atmospheric loss pathway for many important trace gases, such as sulfur dioxide (SO2). The air–sea transfer of SO2 is controlled entirely on the atmospheric side of the air–sea interface due to high effective solubility and other physical–chemical properties. There have been few direct field measurements of such fluxes due to the challenges associated with making fast-response measurements of highly soluble trace gases at very low ambient levels. In this study, we report direct eddy covariance air–sea flux measurements of SO2, sensible heat, water vapor, and momentum. The measurements were made over shallow coastal waters from the Scripps Pier, La Jolla, CA, using negative ion chemical ionization mass spectrometry as the SO2 sensor. The observed transfer velocities for SO2, sensible heat, water vapor, and momentum and their wind speed dependences indicate that SO2 fluxes can be reliably measured using this approach. As expected, the transfer velocities for SO2, sensible heat, and water vapor are lower than that for momentum, demonstrating the contribution of molecular diffusion to the overall air-side resistance to gas transfer. Furthermore, transfer velocities of SO2 were lower than those of sensible heat and water vapor when observed simultaneously. This result is attributed to diffusive resistance in the interfacial layer of the air–sea interface.

Solid-phase Extraction for Analysis of Short-Chain Chlorinated Paraffins in Water Samples

Abstract A method for analysis of short-chain chlorinated paraffins (SCCPs) in water based on solid-phase extraction (SPE) was established using electron capture negative chemical ionization mass spectrometry (GC-ENCI-MS). The SPE parameters, including the sorbent, eluent and elution volume were optimized. The Agilent Bond Elut-C18 was precleaned with 3 mL of hexane and 3 mL of methanol, and subsequently conditioned with 3 mL H2O prior to use. After the water samples were enriched by the cartridge, the sample was washed with 3 mL of 10% (V/V) methanol and eluted with 3 mL of hexane-dichloromethane (1:1, V/V) solution. The results indicated that the limits of detection (LOD) for SCCPs were 18 ng L−1, while the corresponding limits of quantitation (LOQ) were 60 ng L−1. The spiked recovery range was 90%–135%, with a relative standard deviation of less than 10%. Finally, 20 surficial water samples around Beijing were collected and SCCPs contents were analyzed using the proposed method. The SCCPs concentrations ranged from less than LOD to 682 ng L−1 with a mean concentration of 216 ng L−1.

Quantification of folpet and phthalimide in food by gas chromatography and mass spectrometry: Overcoming potential analytical artefacts

Accurate quantification of folpet is problematic because it degrades into phthalimide during sample preparation and analysis by gas chromatography (GC). Thus, EU regulation was recently modified to include phthalimide in the folpet residue definition. However, recent studies have shown that phthalimide could also be generated from different sources, which could lead to an overestimation of the phthalimide content and therefore to false positives. GC coupled with either negative chemical ionisation and single quadrupole mass spectrometry, or electron ionisation with triple quadrupole mass spectrometry (GC-EI-MS/MS), were evaluated for the determination of folpet and phthalimide in food. Both methods were validated in 4 different matrices namely apple puree, rice flour, raspberry puree and infant formula. Better selectivity and precision were obtained with GC-EI-MS/MS. Negligible amounts of phthalimide was found in blank matrices, and validation results met the SANTE/11813/2017 criteria in all matrices at the LOQ concentration levels by using GC-EI-MS/MS.

Identifying Alzheimer's Disease Biomarkers by Analyzing Fatty Acids in Cerebrospinal Fluid and Urine

Although fatty acid oxidation is associated with Alzheimer's disease (AD) pathology, no links have been established between brain lipids and excreted oxidized products. We hypothesize that oxidation of brain polyunsaturated fatty acids (PUFA) can generate dicarboxylic acids (DCA) excreted in urine by AD subjects at different rates compared with cognitively healthy (CH) subjects. Furthermore, this trend can be extended to differentiate CH subjects with normal cerebrospinal fluid (CSF) Aβ42/tau ratios (CH‐NAT) and CH subjects with pathological CSF Aβ42/tau ratios (CH‐PAT).Subjects &gt; 70 years were classified as CH (n=64) or AD (n=26) after neuropsychological assessment. CSF Aβ42 and Tau levels were determined using an ELISA‐based method and a logistic regression of Aβ42/tau ratios used to classify CH‐NAT and CH‐PAT. CSF was fractionated and PUFA levels quantified in supernatant fluid (SF), nanoparticles (NP), and unesterified fatty acid (UFA). DCA was derivatized to pentafluorobenzyl ester, and quantified using gas chromatography and isotope dilution negative ion chemical ionization mass spectrometry. PUFA data is expressed as a percentage of fatty acids detected in CSF fractions while DCA is calculated as a percentage of 7 DCAs (C4–C10) in urine. Links between urinary DCAs and CSF PUFAs were determined using Spearman's ranked correlation.C10 DCA negatively correlated with 6 of 8 PUFAs in SF from CH and also negatively correlated with C20:3n‐3 and C22:6n‐3 in SF from CH‐NAT. In contrast, C9 DCA negatively correlated with 7 of 8 PUFAs in SF from AD. C6 and C8 DCAs positively correlated with SF C18:3n‐3 and C20:3n‐3 in AD, respectively, while C6 DCA negatively correlated with SF C18:2n‐6 from CH‐NAT. C4 DCA negatively correlated with C18:2n‐6, C20:4n‐6, and C22:6n‐3 in SF from CH‐PAT, while C7 DCA positively correlated with C20:4n‐6 in SF from CH‐PAT. In the NP fraction of CH, C4 DCA positively correlated with C20:2n‐6, C20:3n‐3, C20:5n‐3, and C22:5n‐3 PUFAs, while C8 DCA negatively correlated with C20:5n‐3. Only C9 DCA positively correlated with C20:4n‐6 in AD NP fractions. Interestingly, no correlations were found in the NP fraction from CH‐NAT. However, C8 DCA negatively correlated with NP C20:3n‐3, C20:5n‐3, and C22:5n‐3 and C4 DCA positively correlated with NP C20:5n‐3 from CH‐PAT. For UFA of CH, C6 DCA negatively correlated with C20:2n‐6, C20:3n‐3, and C22:6n‐3, while C5 and C7 DCAs positively correlated with homo‐γ‐C20:3n‐6 and C18:2n‐6, respectively. For UFA of CH‐NAT, C4 DCA positively correlated with homo‐γ‐C20:3n‐6, C5 and C8 DCAs negatively correlated with homo‐γ‐C20:3n‐6, and C7 DCA negatively correlated with C18:2n‐6. C5 DCA positively correlated with C18:2n‐6 in UFA from CH‐PAT. C8 DCA positively correlated with unesterified C22:6n‐3, while C9 DCA negatively correlated with unesterified C20:5n‐3 in AD subjects.Differential correlation of urinary DCAs with CSF PUFAs in clinical groups suggests a link with AD pathology. PUFAs and DCAs that segregate CH‐NAT from CH‐PAT are potential biomarkers of early AD.Support or Funding InformationL.K. Whittier and the Helen Posthuma FoundationsThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Association between plasma trans fatty acids concentrations and leucocyte telomere length in US adults.

To assess the relationship between plasma trans-fatty acids (TFAs) levels and leucocyte telomere length (TL) in a US adult population sample. National Health and Nutrition Examination Survey (NHANES) database was used for this study. Gas chromatography was used to separate derivatised fatty acids (Four major TFAs [palmitelaidic acid (C16:1n-7t), trans vaccenic acid (C18:1n-7t), elaidic acid (C18:1n-9t), and linoelaidic acid (C18:2n-6t,9t)]) which were then quatified using negative chemical ionization mass spectrometry. Data analyses used multivariable linear regressions, while accounting for the survey design. A total of 5446 eligible participants, with 46.8% (n = 2550) being men, were included. Their average age was 47.1 years for the total sample, and 47.8 and 46.5 years in men and women respectively (p = 0.085 for men vs. women difference). Concentrations of palmitelaidic acid and linolelaidic acid decreased with increasing length of the telomere (p < 0.05). Univariable linear regressions revealed a significant negative association between levels of the palmitelaidic acid, elaidic acid, vaccenic acid, and linolelaidic acid with TL. However when models were adjusted for age, sex, ethnicity, education, marital status, sub-clinical inflammation, body mass index, and smoking, only palmitelaidic acid and linolelaidic acid remained significant (p < 0.05). TFAs levels and particularly palmitelaidic and linolelaidic acids, are likely negatively associated with telomere lenght. Future studies should explore the potential implications of these associations.

Routine Method for the Analysis of Short‐Chain Chlorinated Paraffins in Surface Water and Wastewater

Short‐chain chlorinated paraffins (SCCPs) are persistent compounds that are included in the list of priority substances in the field of water policy of the European Union in 2001. In this paper, a method based on liquid–liquid extraction and gas chromatography with electron capture detection (GC‐ECD) is evaluated to be proposed for the routine analysis of SCCPs in environmental water. Limits of quantification (LOQ) at ng L−1 levels that allow compliance with the maximum admissible level established in the Directive 2013/39/EU, good precision (lower than 11%) and expanded measurement uncertainties (ISO 11352) (lower than 20%) for surface and wastewater samples are obtained. The good agreement between the results found using GC‐ECD and gas chromatography coupled with negative ion chemical ionization mass spectrometry (GC‐NICI‐MS), with relative errors lower than 13%, showed that GC‐ECD is a reliable method to control the presence of SCCPs in environmental water. The method is applied to river and wastewater samples collected in the Metropolitan Area of Barcelona (Spain). SCCPs are found in all the influents of wastewater treatment plants at concentrations ranging from &lt;0.01 (MLOQ) to 3.20 μg L−1, while in the effluents they are detected in 54% of samples at levels below 0.13 μg L−1. SCCPs are not detected at the intake of a drinking water treatment plant that supply water to Barcelona city and only sporadically in the Llobregat River.

In situ hydrothermal growth of a zirconium-based porphyrinic metal-organic framework on stainless steel fibers for solid-phase microextraction of nitrated polycyclic aromatic hydrocarbons

The authors describe the in-situ hydrothermal growth of a porphyrinic zirconium metal-organic framework (MOF), referred to as PCN-222(Zr), on stainless steel fibers. The PCN-222(Zr) is uniformly deposited on the fiber and displays exceptional thermal and chemical stability. The coated fiber was used for the solid-phase microextraction of nitrated polycyclic aromatic hydrocarbons (NPAHs) in water sample prior to their quantitation by gas chromatography in combination with negative chemical ionization mass spectrometry. Limits of detection (S/N = 3) of 17 selected analytes ranged from 0.10 to 20 ng·L−1. Linear range was from 0.4 to 400 ng·L−1. Intra- and inter-day reproducibility values obtained from a single fiber (six replicates) ranged from 2.2–12.8% and 3.6–12.1%, respectively. Fiber-to-fiber reproducibility for six parallel fibers ranged from 3.3% to 10.3% under the same working conditions. The method was successfully applied to determine NPAHs in environmental water, atmospheric particulate matter (PM2.5), and soil samples. This work demonstrated a prominent prospect of this kinds of stable MOF for applications in extraction techniques.

Influence of bleaching and coloring on ethyl glucuronide content in human hair.

Ethyl glucuronide (EtG) is increasingly used in forensic toxicology as a marker for alcohol use in analyses of hair samples, especially in abstinence control. Some cosmetic treatments are considered to markedly reduce the EtG content. In view of especially many women with coloured hair the present study was performed to further investigate the effect of a variety of colouring procedures (bleaching, tinting, permanent and semi-permanent dyeing, henna) on the EtG content. Untreated hair samples (n=12, EtG 13.9-64.7pg/mg) were re-analyzed (gas chromatography- negative chemical ionization mass spectrometry, 0.8pg/mg quantification limit) after different treatment procedures. A decrease of the EtG content of at least 10% occurred in every case. The reduction in comparison to the untreated hair was expectedly high for permanent dyeing and bleaching with 18.1% of the initial content (median, range 0.0-50.9%) and 18.4% (0.0-46.7%), respectively. For henna this was 38.3% (0.0-83.0%), for tinting 70.4% (29.0-90.8%), for semi-permanent dyeing 41.9% (0.0-77.4%). With permanent hair dye the EtG content was decreased to below 7pg/mg in 10 of 12 cases, in 3 cases even below the LOD (0.2pg/mg). Surprisingly henna treatment without oxidative component had a marked influence, EtG was below 2pg/mg in 2 of 12 samples. The study showed that all tested coloration procedures markedly affected the deposited EtG content. Even temporary or henna coloration may have a marked effect. The present data support the recommendation to exclude hair samples with colour manipulations for analysis on the EtG content as a precaution in alcohol abstinence programs. Copyright © 2017 John Wiley & Sons, Ltd.