The development of a SPME-GC/MS method for the analysis of VOC emissions from historic plastic and rubber materials

Analytical methods have been developed for the analysis of VOC emissions from historic plastic and rubber materials using SPME-GC/MS. Parameters such as analysis temperature, sampling time and choice of SPME fibre coating were investigated and sampling preparation strategies explored, including headspace sampling in vials and in gas sampling bags. The repeatability of the method was evaluated. It was found that a 7. d accumulation time at room temperature, followed by sampling using a DVB/CAR/PDMS fibre, with a sampling time of 60. min at room temperature was a suitable strategy for the detection of VOC emissions from a wide range of historic plastic and rubber artefacts. For 20. ml vials, a sample size of 50. mg was found to be appropriate and grinding the samples improved the repeatability of the analysis and yielded higher levels of emissions. A non-destructive adaptation of the method that could be used directly on historic objects in a museum environment is also presented. The detected emissions improve understanding of ongoing degradation processes within historic plastic and rubber materials, in addition to providing information on material composition

Photocatalytic air-purification: A low-cost, real-time gas detection method

This research demonstrates the use of a gas detector as a feasible alternative to the standardized analytical methods typically found in photocatalytic air-purification ISO standard tests and academic literature. A methyl mercaptan detector is calibrated and validated (for linearity) using a standard gas generator. The detector can be directly connected to the photoreactor exit allowing real-time span gas measurement with data-logging at one minute intervals. The detector successfully differentiated samples with different photocatalytic performance. The use of such detectors offers an easy-to-use, low-cost alternative to gas measurement with applications in academic research, proof-of-concept photocatalytic tests and also as an educational tool

Kinetic field dissipation and fate of endosulfan after application on theobroma cacao farm in tropical Southwestern Nigeria

Endosulfan, 6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano,2,4,3-benzodioxathiepin-3-oxide, is still a pesticide of choice for most cocoa farmers in Southwestern Nigeria, in spite of its persistence, bioaccumulative, toxicological properties, and restriction. A single treatment of 1.4 kg ai/ha (0.5% ai) of technical grade endosulfan (Thiodan, 35EC) was applied to 0.0227 ha of cultivated Theobroma cacao L. (Cocoa) farm at the Cocoa Research Institute of Nigeria (CRIN). Levels of parent endosulfan (α-, β-endosulfan) and major metabolite (endosulfan sulfate) were determined in vegetation and surrounding matrices at days 0, 7, 14, 21, 28, 42, and 60 using GC-MS. Their kinetic variables were determined. Order of ∑endosulfan distribution at day 0 was dry foliage > fresh foliage > bark > pods > soil (0–15 cm). No residual endosulfan was found in cocoa seeds and subsurface soil (15–30 cm). Low residual levels in pods on day 0 may be due to endogenous enzymatic breakdown, with α-isomer more susceptible and α/β-endosulfan ratio being 0.90. Fell dry foliage as mulch was predominantly the receiving matrix for non-target endosulfan sprayed. Volatilization was key in endosulfan dissipation between days 0 and 7 from foliage surfaces (> 60% loss), while dissipation trend was bi-phasic and tri-phasic for vegetation and soil, respectively. ∑endosulfan loss at terminal day ranged between 40.60% (topsoil) and 99.47% (fresh foliage). Iteratively computed half-lives (DT′ 50 ) ranged from 6.48 to 30.13 days for ∑endosulfan in vegetation. Endosulfan was moderately persistent in pods—a potential source for cross contamination of seeds during harvest. Iteratively determined DT′ 50 and initial-final day DT 50 are highly correlated (R = 0.9525; n = 28) and no significant difference (P = 0.05) for both methods

Low-cost colorimetric mercury sensor based on immobilisation of rhodamine B thiolactone in a sustainable agar-agar gel substrate

The global impact of mercury (Hg) pollution requires the development of improved low-cost analytical sensors for Hg determination. Rhodamine B thiolactone (RBT) has been proposed as a colorimetric sensor for Hg2+ as it undergoes ring-opening in the presence of Hg to give a fast, reliable, and easily observed, colour change. In this study a naked-eye biopolymer-based sensor for Hg2+ detection was developed based on RBT-doped agar-agar membranes supported on filter papers. The chromogenic reagent was stable at −18 °C for over two years, whilst the RBT-doped sol–gel membranes prepared from 1% (w/v) agar colloid had a shelf-life of at least 12 weeks at room temperature when stored in the dark. The limit of detection (LOD) for naked-eye sensing was 0.4 μg L−1. For Hg2+ quantification, images of the membranes were recorded using a flatbed scanner and analysed with public-domain ImageJ software. The linear range based on greyscale intensity in the green channel was 0.2–6.0 μg L−1 and the LOD was 0.2 µg L−1. Precision was 10% (n = 3) and spike recoveries were in the range 97–103%. The sensors were regenerated using 10% w/v KI and successfully reused up to 4 times. Compared with other RBT-doped sol–gel sensors, the agar-agar membranes were simpler to prepare, more environmentally friendly, and gave a superior detection limit

A comparative study of selected sorbents for sampling of aromatic VOCs from indoor air

Indoor air canbecome pollutedwith VOCs, and understanding the factors which affect adsorption of VOCs from indoor air is important for: (i) the accurate measurement of VOCs, and (ii) to apply mitigation strategies when high analyte concentrations are measured. In this study four VOCs (toluene, ethylbenzene, cumene and dichlorobenzene) were generated as a constant and controlled polluted air stream of VOCs from a dynamic atmospheric chamber. The effects of relative humidity, and sampling flow rate, on adsorption onto Tenax TA and the relatively new silica adsorbents SBA-15 or MCM-41 were studied

Classifying degraded modern polymeric museum artefacts by their smell

Volatile organic compound (VOC) analysis is a successful method for diagnosing medical conditions such as Alzheimer’s disease. However, despite its relevance to heritage, it has found little application in museums. We report the first use of VOC analysis to ‘diagnose’ degradation in modern polymeric museum artefacts. Modern polymers are increasingly found in museum collections but pose serious conservation difficulties due to unstable and widely varying formulations. Solid-phase microextraction gas chromatography/mass spectrometry and linear discriminant analysis were used to classify samples according to the length of time they had been artificially degraded. Classification accuracies of 50-83% were obtained after validation with separate test sets. The method was applied to three artefacts from collections at Tate to detect evidence of degradation. This novel approach could be used for any material in heritage collections and more widely in the field of polymer degradation

GC-MS fragmentation patterns of sprayed endosulfan and its sulphate metabolite in samples of Theobroma cacao L from a field kinetic study

Most environmental analytical methods for the determination of organochlorine pesticides (OCPs) are multi-residual with other organic compounds co-extracted and co-eluted. This has been observed in GC spectra using classical detectors like electron-capture detector (ECD) even after appropriate clean-up. This limitation could be resolved by using GC-MS methods which are more specific and selective. Thus, a commercial-grade endosulfan treated Theobroma cacao plantation was sampled. Representative samples comprising leaves, stem bark and pulp were obtained between 0.5 h and 60 d after treatment. Samples were analyzed for residual parent endosulfan (α- and β-isomers) as well as the metabolite endosulfan sulphate using an ion trap GC-MS. The retention times and chromatogram peaks obtained for various endosulfan were identified and compared with reference standards, and confirmed with National Institute of Standards and Technology (NIST) library. Results showed that the molecular ion at m/z 407 was exhibited by α- and β- endosulfan, representing the parent molecular ion M+• ([C9H6Cl6SO3]+•). The α-isomer was more thermally stable, hence exhibited more relative abundance. Other predominant peaks were 339, 307, 277, 265, 243, 241, 207, 195, 160, 159, 99 and 75 m/z. The peak at m/z 159 was the base molecular ion. For endosulfan sulphate, the peak at m/z 422 corresponded to parent molecular ion (M+•), while m/z 424 was due to isotopic pattern characteristic of the chlorine atom. The peaks at 387, 357, 289, 272, 229, 206, 170, and 120 m/z were characteristic for the sulphate metabolite. The m/z peak at 272 was the base molecular ion, while m/z 143 may be due to metabolite diol and lactone. These results showed that the various endosulfan species can be identified and confirmed simultaneously using a GC-MS

Kinetic and isotherm studies on the adsorption–desorption of technical-grade endosulfan in loamy soils under Theobroma cacao L cultivation, Southwestern Nigeria

The fate of pesticides in soils is dependent on the adsorption–desorption kinetics, isotherms and soil types. Interactions of technical-grade endosulfan with top soils (top 0–15 cm) from CRIN, Igba and Sore Bale Theobroma cacao L farms in Southwestern Nigeria were studied using the OECD batch isotherm method. The soils were predominately basic (pH 7.1–8.33), while the orders of the total organic carbon (1.32–2.03%) and clay content (10.92–19.11%) were CRIN > Igba > Sore Bale and Igba > CRIN > Sore Bale, respectively. The adsorption of endosulfan was bi-continuous: initially rapid, followed by a slow process, with pseudo-equilibria and plateaus formed between 120 and 240 min. Endosulfan adsorption by soils was due to their greater affinity for organic matter than clay. The adsorption rates fitted better into a pseudo-second-order model (PSOM) than a pseudo-first-order model (PFOM), with the adsorption (kads) and desorption (kdes) rate constants for both isomers ranging from 7.60 × 10−3 to 11.52 × 10−3 min−1 and 1.39 × 10−3 to 3.42 × 10−3 min−1, respectively (i.e. kads > kdes), while kdes (β-isomer) > kdes (α-isomer) for PFOM, but k2_ads < k2_des for the two isomers in PSOM. Additionally, α-endosulfan was adsorptive, with the β-isomer more prone to leaching; both isomers were moderately leachable according to their FAO mobility rankings. The adsorption model did not fit well into a Langmuir isotherm (R2 ≤ 0.948); however, the desorption model did (R2 ≥ 0.991). Freundlich isotherm plots fitted better (R2 ≥ 0.992) and exhibited non-linear curves of types L and S for the adsorption and desorption processes, respectively. The adsorption/desorption coefficients (Kfads and Kfdes) and strengths of adsorption/desorption (1/nads and 1/ndes) for both isomers were from 1.33 ± 0.10 to 4.81 ± 0.18 μg1−1/n (mL)1/n g−1 and 0.503 to 1.402, respectively, in all soils, with Kfads < Kfdes and 1/nads < 1/ndes. Positive hysteresis was observed. CRIN exhibited the highest hysteresis index. The Kfom values were ≤127.14 ± 6.23 mL g−1, while the values of the standard free energy were ΔG0 = −5.11 to −14.05 kJ mol−1 K−1, depicting a spontaneous physisorption process, driven by van der Waals forces, among others. Endosulfan could easily be leached and contaminate the surface and groundwater owing to its faster PSOM desorption rate constant, but TOM and clay could be used as mitigants to reduce its mobility in soils as they have significant affinity for the pesticide

Deficient histone H3 propionylation by BRPF1-KAT6 complexes in neurodevelopmental disorders and cancer

Lysine acetyltransferase 6A (KAT6A) and its paralog KAT6B form stoichiometric complexes with bromodomain- and PHD finger-containing protein 1 (BRPF1) for acetylation of histone H3 at lysine 23 (H3K23). We report that these complexes also catalyze H3K23 propionylation in vitro and in vivo. Immunofluorescence microscopy and ATAC-See revealed the association of this modification with active chromatin. Brpf1 deletion obliterates the acylation in mouse embryos and fibroblasts. Moreover, we identify BRPF1 variants in 12 previously unidentified cases of syndromic intellectual disability and demonstrate that these cases and known BRPF1 variants impair H3K23 propionylation. Cardiac anomalies are present in a subset of the cases. H3K23 acylation is also impaired by cancer-derived somatic BRPF1 mutations. Valproate, vorinostat, propionate and butyrate promote H3K23 acylation. These results reveal the dual functionality of BRPF1-KAT6 complexes, shed light on mechanisms underlying related developmental disorders and various cancers, and suggest mutation-based therapy for medical conditions with deficient histone acylation

Corporate ethical identity as a determinant of firm performance : a test of the mediating role of stakeholder satisfaction

In this article, we empirically assess the impact of corporate ethical identity (CEI) on a firm’s financial performance. Drawing on formulations of normative and instrumental stakeholder theory, we argue that firms with a strong ethical identity achieve a greater degree of stakeholder satisfaction (SS), which, in turn, positively influences a firm’s financial performance. We analyze two dimensions of the CEI of firms: corporate revealed ethics and corporate applied ethics. Our results indicate that revealed ethics has informational worth and enhances shareholder value, whereas applied ethics has a positive impact through the improvement of SS. However, revealed ethics by itself (i.e. decoupled from ethical initiatives) is not sufficient to boost economic performance.Publicad