Selecting and identifying gas-phase protonation isomers of nicotineH+ using combined laser, ion mobility and mass spectrometry techniques

The detection and assignment of protonation isomers, termed protomers, of gas-phase ions remains a challenge in mass spectrometry. With the emergence of ion-mobility techniques combined with tuneable-laser photodissociation spectroscopy, new experimental combinations are possible to now meet this challenge. In this paper, the differences in fragmentation and electronic spectroscopy of singly protonated (S)-nicotine (nicH+) ions are analysed using action spectroscopy in the ultraviolet region and field asymmetric ion mobility spectrometry (FAIMS). Experiments are supported by quantum chemical calculations (DFT, TD-DFT and CC2) of both spectroscopic and thermochemical properties. Electrospray ionisation (ESI) of (S)-nicotine from different solvents leads to different populations of two nicH+ protomers corresponding to protonation on the pyridine nitrogen and pyrrolidine nitrogen, respectively. FAIMS gives partial resolution of these protomers and enables characteristic product ions to be identified for each isomer as verified directly by analysis of product-ion specific action spectroscopy. It is shown that while characteristic, these product ions are not exclusive to each protomer. Calculations of vertical electronic transitions assist in rationalising the photodissociation action spectra. The integration of photodissociation action spectroscopy with FAIMS-mass spectrometry is anticipated to be a useful approach for separating and assigning protonation isomers of many other small molecular ions

The impact of changes in opioid dependency treatment upon COVID-19 transmission in Sydney, Australia: a retrospective longitudinal observational study

Abstract Background In April 2020, in response to the COVID-19 public health emergency, South Eastern Sydney Local Health District (SESLHD) Drug and Alcohol services modified their delivery of opioid dependency treatment (ODT) to reduce spread of COVID-19 and maintain continuity of care by increasing use of takeaway doses (TADs), transferring clients to local community pharmacies for dosing and encouraging the use of long-acting depot buprenorphine (LADB) which enabled once a month dosing. Methods This study was a retrospective longitudinal case–control study conducted from August 1st, to November 30th, 2021. Eligible clients were those admitted for treatment with SESLHD ODT Services prior to August 1st,2021 and who remained in treatment beyond November 30th, 2021. COVID-19 diagnoses were determined by a COVID-19 PCR and extracted from the electronic Medical Records (eMR) Discern Reporting Portal. Demographic, clinical and dosing related data were collected from eMR and the Australian Immunisation Register (AIR). Results Clients attending SESLHD ODT services had significantly greater odds of acquiring COVID-19 than the NSW adult population at large (OR: 13.63, 95%CI: 9.64,18.88). Additionally, amongst SESLHD ODT clients, being of Aboriginal and Torres Strait Islander origin was associated with greater odds of acquiring COVID-19 (OR = 2.18, CI: 1.05,4.53); whilst being employed (OR = 0.06, CI:0.01,0.46), receiving doses at pharmacy (OR = 0.43, CI: 0.21,0.89), and being vaccinated (OR = 0.12, CI: 0.06,0.26) were associated with lower odds. Every additional day of attendance required for dosing was associated with a 5% increase in odds of acquiring COVID-19 (OR = 1.05, CI: 1.02,1.08). Conclusions Clients attending SESLHD ODT services are significantly more likely to acquire COVID-19 than the NSW population at large. Promoting vaccination uptake, transferring clients to pharmacy, and reducing the frequency of dosing (by use of takeaway doses or long-acting depot buprenorphine) are all potential methods to reduce this risk

Gas phase reactions of iodide and bromide anions with ozone: evidence for stepwise and reversible reactions

Despite the impacts - both positive and negative - of atmospheric ozone for life on Earth, there remain significant gaps in our knowledge of the products, mechanisms and rates of some of its most fundamental gas phase reactions. This incomplete understanding is largely due to the experimental challenges involved in the study of gas-phase reactions of ozone and, in particular, the identification of short-lived reaction intermediates. Here we report direct observation of the stepwise reaction of the halide anions iodide (I-) and bromide (Br-) with ozone to produce XO3- (where X = I and Br, respectively). These results substantially revise the rate constant for the I- + O3 reaction to 1.1 (± 0.5) × 10-12 cm3 molecule-1 s-1 (0.13% efficiency) and the Br- + O3 reaction to 6.2 (± 0.4) × 10-15 cm3 molecule-1 s-1 (0.001% efficiency). Exploiting five-orders of temporal dynamic range on a linear ion trap mass spectrometer enabled explicit measurement of the rate constants for the highly efficient intermediate, XO- + O3 and XO2- + O3, reactions thus confirming a stepwise addition of three oxygen atoms (i.e., X- + 3O3 → XO3- + 3O2) with the first addition representing the rate determining step. Evidence is also presented for (i) slow reverse reactions of XO- and XO2-, but not XO3-, with molecular oxygen and (ii) the photodissociation of IO-, IO2- and IO3- to release I-. Collectively, these results suggest relatively short lifetimes for Br- and I- in the tropospere with direct gas-phase oxidation by ozone playing a role in both the formation of atmospheric halogen oxides and, conversely, in the ozone depletion associated with springtime polar bromine explosion events

Selecting and identifying gas-phase protonation isomers of nicotineH+ using combined laser, ion mobility and mass spectrometry techniques

The detection and assignment of protonation isomers, termed protomers, of gas-phase ions remains a challenge in mass spectrometry. With the emergence of ion-mobility techniques combined with tuneable-laser photodissociation spectroscopy, new experimental combinations are possible to now meet this challenge. In this paper, the differences in fragmentation and electronic spectroscopy of singly protonated (S)-nicotine (nicH+) ions are analysed using action spectroscopy in the ultraviolet region and field asymmetric ion mobility spectrometry (FAIMS). Experiments are supported by quantum chemical calculations (DFT, TD-DFT and CC2) of both spectroscopic and thermochemical properties. Electrospray ionisation (ESI) of (S)-nicotine from different solvents leads to different populations of two nicH+ protomers corresponding to protonation on the pyridine nitrogen and pyrrolidine nitrogen, respectively. FAIMS gives partial resolution of these protomers and enables characteristic product ions to be identified for each isomer as verified directly by analysis of product-ion specific action spectroscopy. It is shown that while characteristic, these product ions are not exclusive to each protomer. Calculations of vertical electronic transitions assist in rationalising the photodissociation action spectra. The integration of photodissociation action spectroscopy with FAIMS-mass spectrometry is anticipated to be a useful approach for separating and assigning protonation isomers of many other small molecular ions.</p

Direct Observation of Photodissociation Products from Phenylperoxyl Radicals Isolated in the Gas Phase

Gas phase peroxyl radicals are central to our chemical understanding of combustion and atmospheric processes and are typically characterized by strong absorption in the UV (lambda(max) approximate to 240 nm). The analogous maximum absorption feature for arylperoxyl radicals is predicted to shift to the visible but has not previously been characterized nor have any photoproducts arising from this transition been identified. Here we describe the controlled synthesis and isolation in vacuo of an array of charge-substituted phenylperoxyl radicals at room temperature, including the 4-(N,N,N-trimethylammonium)methyl phenylperoxyl radical cation (4-Me3N[+]CH2-C6H4OO center dot), using linear ion-trap mass spectrometry. Photodissociation mass spectra obtained at wavelengths ranging from 310 to 500 nm reveal two major photoproduct channels corresponding to homolysis of aryl-OO and arylO-O bonds resulting in loss of O-2 and O, respectively. Combining the photodissociation yields across this spectral window produces a broad (FWHM approximate to 60 nm) but clearly resolved feature centered at lambda(max) = 403 nm (3.08 eV). The influence of the charge-tag identity and its proximity to the radical site are investigated and demonstrate no effect on the identity of the two dominant photoproduct channels. Electronic structure calculations have located the vertical (B) over tild

Reported improvement in main condition: comparing prescribed cannabinoids using PGIC scores.

Reported improvement in main condition: comparing prescribed cannabinoids using PGIC scores.</p

Gas phase reactions of iodide and bromide anions with ozone: Evidence for stepwise and reversible reactions

Despite the impacts - both positive and negative - of atmospheric ozone for life on Earth, there remain significant gaps in our knowledge of the products, mechanisms and rates of some of its most fundamental gas phase reactions. This incomplete understanding is largely due to the experimental challenges involved in the study of gas-phase reactions of ozone and, in particular, the identification of short-lived reaction intermediates. Here we report direct observation of the stepwise reaction of the halide anions iodide (I−) and bromide (Br−) with ozone to produce XO3−(where X = I and Br, respectively). These results substantially revise the rate constant for the I−+ O3reaction to 1.1 (± 0.5) × 10−12cm3molecule−1s−1(0.13% efficiency) and the Br−+ O3reaction to 6.2 (± 0.4) × 10−15cm3molecule−1s−1(0.001% efficiency). Exploiting five-orders of temporal dynamic range on a linear ion trap mass spectrometer enabled explicit measurement of the rate constants for the highly efficient intermediate, XO−+ O3and XO2−+ O3, reactions thus confirming a stepwise addition of three oxygen atoms (i.e., X−+ 3O3→ XO3−+ 3O2) with the first addition representing the rate determining step. Evidence is also presented for (i) slow reverse reactions of XO−and XO2−, but not XO3−, with molecular oxygen and (ii) the photodissociation of IO−, IO2−and IO3−to release I−. Collectively, these results suggest relatively short lifetimes for Br−and I−in the tropospere with direct gas-phase oxidation by ozone playing a role in both the formation of atmospheric halogen oxides and, conversely, in the ozone depletion associated with springtime polar bromine explosion events.</p

Driving patterns of participants on prescribed THC vs prescribed CO.

Driving patterns of participants on prescribed THC vs prescribed CO.</p

Main reasons for use of prescribed medicinal cannabis users by cannabinoid product production composition.

Main reasons for use of prescribed medicinal cannabis users by cannabinoid product production composition.</p