Determination of Benzoic Acid and Benzyl Alcohol in E-Liquids (JUULTM Pods) by Isotopic Dilution High-Performance Liquid Chromatography and Tandem Mass Spectrometry

Summary The new pod devices like JUULTM, Vuse AltoTM, mybluTM, and other “pod-mod” related products had a huge impact on the e-cigarette market, especially among teens and young adults due in particular to aggressive marketing on social media, wide availability, and discrete use due to their special design. These pod devices are designed to deliver nicotine levels per puff comparable to combustible cigarettes while producing smaller amounts of visible exhaled aerosol from the heating of e-liquids. Some of these liquids contain high concentrations of acids, such as benzoic acid, to allow higher nicotine deliveries with less harshness and throat irritation. Benzoic acid is a potential source of the human carcinogen benzene and a chemical of concern. Besides acids, flavoring agents such as benzyl alcohol, a local anesthetic that could facilitate tobacco smoke inhalation are also common in these devices. Both benzoic acid and benzyl alcohol in e-liquids might be of relevance for the health risk of vapers. An isotope dilution high-performance liquid chromatography-tandem mass spectrometry (ID-HPLC-MS/MS) method has been developed for the detection of benzoic acid and benzyl alcohol in the JUULTM brand e-liquids. The sample preparation consisted of a simple dilution followed by a mechanical stirring process. ID-HPLC-MS/MS was used to separate, identify, and quantify the benzoic acid and/or benzyl alcohol in diluted extracts. Detection limits were 0.11 and 9.05 ng/μL for benzyl alcohol and benzoic acid, respectively. Product variability estimated from the analysis of seven different e-liquids in triplicates (n = 21) yielded relative standard deviations ranging from 4.3% to 16.0% for benzyl alcohol and 6.3% to 11.1% for benzoic acid. The amount of benzoic acid (32.8 ± 2.8 mg/g; 3.3 ± 0.3%, w/w) and the nicotine-benzoic acid molar ratio (1.15 ± 0.02) remained relatively consistent among pod flavors. [Contrib. Tob. Nicotine Res. 30 (2021) 212–220]

P-180 Bisphenols are present in culture media used for ART and cell culture

Study question Do plastic laboratory consumables and cell culture media used in human ART contain bisphenols? Summary answer Human embryo development media contained bisphenols close to the nanomolar concentration range while no release of bisphenols by plastic consumables was detected under routine conditions. What is known already The deleterious effect of the endocrine disruptor bisphenol A (BPA) on female fertility raised concerns regarding ART outcome. BPA was detected neither in media nor in the majority of plastic consumables used in ART, however it might have already been replaced by its structural analogs, including bisphenol S (BPS). Study design, size, duration Seventeen plastic consumables and 18 cell culture and ART media were assessed for the presence of bisphenols. Participants/materials, setting, methods Ten different bisphenols (bisphenol A, S, AF, AP, B, C, E, F, P, and Z) were measured using an isotopic dilution according to an on-line solid phase extraction / liquid chromatography/mass spectrometry method. Main results and the role of chance While all the plastic consumables of this study did contain bisphenols, none of them did release bisphenols under routine conditions. Moreover, 16 of the 18 cell culture and ART media assessed contained bisphenols, including 8 among the 10 media used in human ART. Five human ART media exhibited bisphenol concentrations higher than 0.8 nM and reached up to 3.2 nM (799 ng/L). Limitations, reasons for caution Further studies are required to investigate a greater number of ART media to identify less potentially harmful ones, in terms of bisphenol content. Wider implications of the findings As BPS has already been reported to impair oocyte quality at nanomolar concentrations, its presence in ART media, at a similar concentration range, could contribute to a decrease in the ART success rate. Thus far, there has been no regulation of these compounds in the ART context. Trial registration number Not applicable

P–180 Bisphenols are present in culture media used for ART and cell culture

Study question Do plastic laboratory consumables and cell culture media used in human ART contain bisphenols? Summary answer Human embryo development media contained bisphenols close to the nanomolar concentration range while no release of bisphenols by plastic consumables was detected under routine conditions. What is known already The deleterious effect of the endocrine disruptor bisphenol A (BPA) on female fertility raised concerns regarding ART outcome. BPA was detected neither in media nor in the majority of plastic consumables used in ART, however it might have already been replaced by its structural analogs, including bisphenol S (BPS). Study design, size, duration Seventeen plastic consumables and 18 cell culture and ART media were assessed for the presence of bisphenols. Participants/materials, setting, methods Ten different bisphenols (bisphenol A, S, AF, AP, B, C, E, F, P, and Z) were measured using an isotopic dilution according to an on-line solid phase extraction / liquid chromatography/mass spectrometry method. Main results and the role of chance While all the plastic consumables of this study did contain bisphenols, none of them did release bisphenols under routine conditions. Moreover, 16 of the 18 cell culture and ART media assessed contained bisphenols, including 8 among the 10 media used in human ART. Five human ART media exhibited bisphenol concentrations higher than 0.8 nM and reached up to 3.2 nM (799 ng/L). Limitations, reasons for caution Further studies are required to investigate a greater number of ART media to identify less potentially harmful ones, in terms of bisphenol content. Wider implications of the findings: As BPS has already been reported to impair oocyte quality at nanomolar concentrations, its presence in ART media, at a similar concentration range, could contribute to a decrease in the ART success rate. Thus far, there has been no regulation of these compounds in the ART context. Trial registration number Not applicable

The effect of soil properties on zinc lability and solubility in soils of Ethiopia – an isotopic dilution study

Zinc (Zn) deficiency is a widespread nutritional problem in human populations, especially in sub-Saharan Africa (SSA). The Zn concentration of crops consumed depends in part on the Zn status of the soil. Improved understanding of factors controlling the phyto-availability of Zn in soils can contribute to potential agronomic interventions to tackle Zn deficiency, but many soil types in SSA are poorly studied. Soil samples (n=475) were collected from a large part of the Amhara Region of Ethiopia, where there is widespread Zn deficiency. Zinc status was quantified by measuring several fractions, including the pseudo-total (aqua regia digestion; ZnTot), available (DTPA (diethylenetriamine pentaacetate) extractable; ZnDTPA), soluble (dissolved in 0.01 M Ca(NO3); ZnSoln) and isotopically exchangeable Zn, using the enriched stable Zn isotope 70Zn (ZnE). Soil geochemical properties were assessed for their influence on Zn lability and solubility. A parameterized geochemical assemblage model (Windermere Humic Aqueous Model – WHAM) was also employed to predict the solid phase fractionation of Zn in tropical soils rather than using sequential chemical extractions. ZnTot ranged from 14.1 to 291 mg kg−1 (median = 100 mg kg−1), whereas ZnDTPA in the majority of soil samples was less than 0.5 mg kg−1, indicating widespread phyto-available Zn deficiency in these soils. The labile fraction of Zn in soil (ZnE as % ZnTot) was low, with median and mean values of 4.7 % and 8.0 %, respectively. Labile Zn partitioning between the solid and the solution phases of soil was highly pH dependent, where 94 % of the variation in the partitioning coefficient of 70Zn was explained by soil pH. Similarly, 86 % of the variation in ZnSoln was explained by soil pH. Zinc distribution between adsorbed ZnE and ZnSoln was controlled by pH. Notably, Zn isotopic exchangeability increased with soil pH. This contrasts with literature on contaminated and urban soils and may arise from covarying factors, such as contrasting soil clay mineralogy across the pH range of the soils used in the current study. These results could be used to improve agronomic interventions to tackle Zn deficiency in SSA.

Isotopic carbon turnover in pig hoof and rib

The objective of this study was to evaluate the behavior of carbon incorporation and turnover in hoof and ribs of pigs at different periods of development in the search for tissues that reflect longer the former diet. We used 132 commercial hybrids (barrows and females), weaned at an average age of 21 days, distributed in a completely randomized design with four treatments on different days of substitution of corn (C4 cycle plant grain) diets with broken rice (C3 cycle plant grain) at 21, 42, 63 and 110 days of age to change the carbon-13 isotope signal. By means of isotopic dilution curves, we observed that animals whose C4 diet was replaced with C3 diet at 21, 42, 63 and 110 days of age, for hoof and rib, reached a new level of isotope equilibrium. Bone samples are better choices to reflect the former diet, due to conservation of the isotopic signal for longer.

13C Isotope Labelling to Follow the Flux of Photorespiratory Intermediates

Measuring the carbon flux through metabolic pathways in intact illuminated leaves remains challenging because of, e.g., isotopic dilution by endogenous metabolites, the impossibility to reach isotopic steady state, and the occurrence of multiple pools. In the case of photorespiratory intermediates, our knowledge of the partitioning between photorespiratory recycling, storage, and utilization by other pathways is thus rather limited. There has been some controversy as to whether photorespiratory glycine and serine may not be recycled, thus changing the apparent stoichiometric coefficient between photorespiratory O2 fixation and CO2 release. We describe here an isotopic method to trace the fates of glycine, serine and glycerate, taking advantage of positional 13C content with NMR and isotopic analyses by LC–MS. This technique is well-adapted to show that the proportion of glycerate, serine and glycine molecules escaping photorespiratory recycling is very small.