Purity Assessment of Honey Based on Compound Specific Stable Carbon Isotope Ratios Obtained by LC-IRMS.

BACKGROUND: The use of stable carbon isotope ratios (δ13C) of sugar fractions of honey is a powerful tool to detect adulteration with sugar syrups. This is accomplished by calculating differences of the δ13C values between individual honey saccharides and comparing them to published purity criteria. A liquid chromatography-isotope ratio mass spectrometry (LC-IRMS) method for the determination of δ13C values of sugars in honey was previously validated by an interlaboratory comparison but no further guidance was given how to include the obtained precision figures of the compound specific δ13C values in the purity assessment of honey. OBJECTIVE: To use existing data to estimate the standard deviation of the repeatability (sr) and reproducibility (sR) of differences (Δ Î´13C) between the δ13C values of individual honey saccharides. METHODS: Previously published δ13C values were used to calculate differences (Δ Î´13C values) between δ13C fructose-δ13C glucose, δ13C glucose-δ13C disaccharides, etc in a honey sample; sr and sR of Δ Î´13C values were calculated according to ISO 5725-2:2019. RESULTS: The Δ Î´13C sr and sR values were essentially of the same magnitude as the sr and sR values of δ13C values of the sugar fractions. The precision of the Δ Î´13C values was used to estimate the critical difference for comparing a test result with a reference value according to ISO 5725-6:1994. This varied between 0.02 ‰ and 0.40 ‰. CONCLUSION: The estimated critical differences can be used to determine whether a honey test result complies with published Δ Î´13C purity criteria. HIGHLIGHT: The proposed procedure will increase the confidence in decisions based on compound specific δ13C values regarding the conformity of honey with published purity criteria.

Results of an Interlaboratory Comparison of a Liquid Chromatography-Isotope Ratio Mass Spectrometry Method for the Determination of 13C/12C Ratios of Saccharides in Honey.

BACKGROUND: Stable carbon isotope analysis of sugars in honey by LC-isotope ratio mass spectrometry (IRMS) is a useful tool for detecting adulteration of honey with extraneous sugar. Purity criteria based on 13C/12C ratios of saccharides in honey, determined by LC-IRMS of a large number of authentic honey samples, have been elaborated. However, no interlaboratory comparison (ILC) has yet been performed to estimate the precision of the method under reproducibility conditions. OBJECTIVE: To address this knowledge gap an ILC involving 14 laboratories and using six honey samples was conducted. METHODS: The participants were allowed to use their LC-IRMS-based method of choice for sample preparation and compound separation. RESULTS: The precision figures were estimated according to ISO 5725:1994. The repeatability relative standard deviation (RSDr) for the determination of δ13C values of fructose and glucose varied between 0.3 and 0.5%, with 0.3 and 1.0% for disaccharides, and 0.7 and 2.8% for trisaccharides. The RSDR varied between 0.8 and 1.8% for the monosaccharides, 1.0 and 1.5% for disaccharides, and 1.4 and 2.8% for trisaccharides. CONCLUSION: Based on the obtained precision data the LC-IRMS method for the determination of 13C/12C ratios of saccharides in honey was considered fit for the conformity assessment of honey with established purity criteria. HIGHLIGHTS: Precision estimates for a LC-IRMS method to determine 13C/12C ratios of saccharides in honey were obtained through an ILC. The data created can form the basis for the standardization of the method by interested standards-developing organizations for use in official control.

Magnetic nanoparticle-mediated isolation of functional bacteria in a complex microbial community.

Although uncultured microorganisms have important roles in ecosystems, their ecophysiology in situ remains elusive owing to the difficulty of obtaining live cells from their natural habitats. In this study, we employed a novel magnetic nanoparticle-mediated isolation (MMI) method to recover metabolically active cells of a group of previously uncultured phenol degraders, Burkholderiales spp., from coking plant wastewater biosludge; five other culturable phenol degraders-Rhodococcus sp., Chryseobacterium sp. and three different Pseudomonas spp.-were also isolated from the same biosludge using traditional methods. The kinetics of phenol degradation by MMI-recovered cells (MRCs) was similar to that of the original sludge. Stable isotope probing (SIP) and pyrosequencing of the 16S rRNA from the 'heavy' DNA ((13)C-DNA) fractions indicated that Burkholderiales spp. were the key phenol degraders in situ in the biosludge, consistent with the results of MRCs. Single-cell Raman micro-spectroscopy was applied to probe individual bacteria in the MRCs obtained from the SIP experiment and showed that 79% of them were fully (13)C-labelled. Biolog assays on the MRCs revealed the impact of various carbon and nitrogen substrates on the efficiency of phenol degradation in the wastewater treatment plant biosludge. Specifically, hydroxylamine, a metabolite of ammonia oxidisation, but not nitrite, nitrate or ammonia, inhibited phenol degradation in the biosludge. Our results provided a novel insight into the occasional abrupt failure events that occur in the wastewater treatment plant. This study demonstrated that MMI is a powerful tool to recover live and functional cells in situ from a complex microbial community to enable further characterisation of their physiology.

Assessment of exposure to PCDD/F, PCB, and PAH at a basic oxygen Steelmaking (BOS) and an iron ore sintering plant in the UK.

An assessment was carried out at a UK integrated steelworks to investigate the exposure of workers via inhalation to dioxins [polychlorinated dibenzo-p-dioxins (PCDD/F)], polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAH) including benzo[a]pyrene (B[a]P). Investigations focused on a basic oxygen steelmaking (BOS) plant and an iron ore sintering plant. The highest concentrations of PCDD/F and dioxin-like PCB were found at the BOS vessels and sinter strand area at the BOS and sinter plant, respectively. A risk assessment was carried out by comparing the daily intake of PCDD/F and PCB via inhalation with the recommended tolerable daily intake (TDI) proposed by the World Health Organisation (WHO). For the most exposed category of worker in this study (i.e. sinter plant workers inside the strand area), the estimated daily intake via inhalation was estimated to be 0.25 pg WHO-toxic equivalent concentrations (TEQ) kg(-1) body weight (bw). Considering that the average UK adult exposure to PCDD/F from the diet is 1.8 pg WHO-TEQ kg(-1) bw day(-1), the results indicated that the estimated daily intake of PCDD/F and PCB via inhalation for sinter plant workers would not result in the recommended range of the TDI (1-4 pg WHO-TEQ kg(-1) bw day(-1)) being exceeded. Cancer risks for a 40-year occupational exposure period were determined by multiplying the estimated intake by the inhalation cancer potency factor for 2,3,7,8-tetrachlorodibenzo-p-dioxin. For the most exposed category of worker, cancer risks from exposure to PCDD/F and PCB ranged from 2.5 × 10(-6) to 5.2 × 10(-5). Under most regulatory programmes, excess cancer risks between 1.0 × 10(-6) and 1.0 × 10(-4) indicate an acceptable range of cancer risk, suggesting a limited risk from PCDD/F and PCB exposure for workers in the sinter plant. With regard to PAH, B[a]P concentrations were typically <10 ng m(-3) at all locations at both the sinter plant and the BOS plant. In several cases, particularly at the sinter plant, B[a]P concentrations were well below or only marginally above the target value of 1 ng m(-3) specified in ambient air by the European Commission in the fourth 'Daughter' Directive of the Air Quality Framework Directive suggesting a very low risk of exposure for workers. For PAH, excess cancer risks ranged from 2.4 × 10(-6) to 7.3 × 10(-6) for BOS plant workers and from for 5.3 × 10(-7) to 1.5 × 10(-5) for sinter plant workers, well within the acceptable range proposed by the US EPA.

Whole-cell bacterial bioreporter for actively searching and sensing of alkanes and oil spills.

Acinetobacter baylyi ADP1 was found to tolerate seawater and have a special ability of adhering to an oil-water interface of 10-80 µm emulsified mineral and crude oil droplets. These properties make ADP1 an ideal bacterial chassis for constructing bioreporters that are able to actively search and sense oil spill in water and soils. Acinetobacter baylyi bioreporter ADPWH_alk was developed and applied to the detection of alkanes and alkenes in water, seawater and soils. Bioreporter ADPWH_alk was able to detect a broad range of alkanes and alkenes with carbon chain length from C7 to C36. So far, ADPWH_alk is the only bioreporter that is able to detect alkane with carbon chain length greater than C18. This bioreporter responded to the alkanes in about 30 min and it was independent to the cell growth phase because of two point mutations in alkM promoter recognized by alkane regulatory protein ALKR. ADPWH_alk was applied to detect mineral oil, Brent, Chestnut and Sirri crude oils in water and seawater in the range 0.1-100 mg l(-1), showing that the bioreporter oil detection was semi-quantitative. This study demonstrates that ADPWH_alk is a rapid, sensitive and semi-quantitative bioreporter that can be useful for environmental monitoring and assessment of oil spills in seawater and soils.

Exposure assessment of workers to airborne PCDD/Fs, PCBs and PAHs at an electric arc furnace steelmaking plant in the UK.

Occupational exposure studies were undertaken at a UK electric arc furnace (EAF) steelmaking plant to investigate the exposure of workers via inhalation to dioxins, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) including benzo[a]pyrene (B[a]P). Surveys were undertaken in areas including the melting shop, the casting department and a furnace control cabin. The highest concentrations of dioxins and PCBs were found inside the melting shop nearby EAFs, whereas dioxin and PCB concentrations in the casting department and inside the control cabin were significantly lower. Risk characterization was carried out by comparing the daily intake of dioxins and PCBs through inhalation with the recommended tolerable daily intake (TDI). Health risk assessments were also carried out by combining exposure data with inhalation cancer potency factors to quantify the cancer risk. For the most exposed category of workers (melting shop workers), the estimated daily intake via inhalation was 0.35 pg WHO-TEQ kg(-1) body weight (bw) in the worst case scenario. Considering that the average UK adult exposure to dioxins from the diet is 1.8 pg WHO-TEQ kg(-1) bw day(-1), the results indicated that the estimated daily intake of dioxins via inhalation at the EAF would not result in the recommended range of the TDI (1-4 pg WHO-TEQ kg(-1) bw day(-1)) being exceeded. Cancer risks for a 40-year occupational exposure period were determined by multiplying the inhalation dose by the inhalation cancer potency factor for 2,3,7,8-tetrachlorodibenzo-p-dioxin. For melting shop workers, cancer risks from exposure to dioxins and PCBs ranged from 2.05 x 10(-5) to 7.54 x 10(-5). Under most regulatory programmes, excess cancer risks between 1.0 x 10(-4) and 1.0 x 10(-6) indicate an acceptable range of excess cancer risk, suggesting a limited risk from dioxin exposure for workers in the EAF plant. For the calculation of excess cancer risks, no account has been taken of the protection provided by protective respiratory equipment worn by EAF workers. If personal protective equipments were taken into consideration, it is likely that the excess cancer risks for EAF workers would have been lower and considered as negligible. The highest concentrations of PAHs were found in the melting shop and the casting areas of the plant. In the melting shop area, B[a]P concentrations ranged from 1.4 to 24.5 ng m(-3), with a mean value of 7 ng m(-3). No workplace exposure limits have been published by the Health and Safety Executive in the UK for PAHs; however, the B[a]P concentrations found were below the limit value of 150 ng m(-3) (8-h time-weighted average) specified for workplace exposure in France. Exposure assessment of workers to PAHs via inhalation was carried out by calculating a potential cancer risk considering a 40-year occupational exposure period and B[a]Peq concentrations. Estimated cancer risks for the most exposed category of workers (i.e. melting shop workers) ranged from 3.66 x 10(-6) to 1.64 x 10(-5). The cancer risks determined in this study were well within an acceptable range of excess cancer risk of 1.0 x 10(-4) to 1.0 x 10(-6), specified by the US Environmental Protection Agency.

PCDD/F and "Dioxin-like" PCB emissions from iron ore sintering plants in the UK.

Investigations have been carried out at the three Corus UK sinter plants over the period 2002-2004 to characterise the emissions of both 2,3,7,8-PCDD/Fs and WHO-12 PCBs, to estimate annual mass releases of these organic micro-pollutants using the I-TEF and WHO-TEF schemes, and to investigate the formation of PCBs in the iron ore sintering process. Results showed that the sintering of iron ore produces a characteristic WHO-12 PCB and PCDD/F congener pattern that is substantially the same for all UK sinter plants. With regard to WHO-12 PCBs, the most abundant congeners were typically PCBs 118 (6-9 ngNm(-3)), 105 (2-4 ngNm(-3)) and 77 (2-3 ngNm(-3)). All other WHO-12 PCBs were also detected at concentrations around 1 ngNm(-3). All sinter plants investigated exhibited very similar TEQ concentrations. WHO-12 PCB emissions were in the range 0.042-0.111 ngWHO-TEQNm(-3), whereas PCDD/F emissions ranged from 0.39 to 1.62 ngWHO-TEQNm(-3). PCDF congeners were the main contributors to the overall TEQ in sintering emissions (ca. 85%). Amongst WHO-12 PCBs, PCB 126 was the only noteworthy contributor to total TEQ (ca. 5-7%), a similar contribution to that from PCDDs. Based on the measurements that Corus UK has undertaken at these three sinter plants, annual mass releases of WHO-12 PCBs and PCDD/Fs have been calculated. For UK sinter plants, a total mass release of 29.5 g WHO-TEQ per annum [WHO-12 PCBs+PCDD/Fs] has been estimated, representing 9% of the total PCDD/F emissions to the UK atmosphere. Measurements were also carried out at a UK sinter plant to determine the windleg emission profile of WHO-12 PCBs. Results showed that WHO-12 PCBs were formed in the same regions of the sinter strand as 2,3,7,8-PCDD/Fs, indicating that there was a strong correlation between the formation of WHO-12 PCBs and PCDD/Fs in the iron ore sintering process.

Development and validation of a method for analysis of "dioxin-like" PCBs in environmental samples from the steel industry.

A method, previously used for determination of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), has been modified for quantitative analysis of "dioxin-like" polychlorobiphenyls (PCBs) in environmental samples from the steel industry. The existing sample clean-up procedure, involving liquid chromatography on multi-layered silica and Florisil columns, has been extended to include a third chromatography stage on a basic alumina stationary phase. The additional clean-up stage is required for PCB analysis in order to eliminate interferences from relatively large concentrations of saturated cyclic and aliphatic hydrocarbons. Samples were analysed for WHO-12 congeners using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) and standard solutions of the method US EPA 1668A. Replicate analysis of method blanks revealed background contamination for PCBs 118, 105 and 77, which are generally abundant in ambient air. These contaminants were taken into account using a subtraction method. The entire procedure was validated by replicate analysis (N = 3) of a certified reference sediment. The RSD for each WHO-12 congener was below 15%, 13C12-labelled PCB internal standard recoveries were in the range 70-95%. A waste dust sample collected in the electrostatic precipitator of a UK sinter plant was analysed for determination of PCDD/Fs and WHO-12 PCBs and exhibited a PCDD/F I-TEQ of 148.5 +/- 21.2 ngkg(-1) and a WHO-TEQ of 7.2 +/- 1.5 ngkg(-1). WHO-12 congeners contributed only 4.6% to the overall TEQ and PCB 126 was the major congener contributing to the WHO-TEQ (96%). The contribution to the overall TEQ of the waste dust sample was mainly attributed to PCDF followed by PCDD, which accounted for 86.6% and 8.7% to the overall TEQ, respectively.