Which illicit drugs are injected in Oslo? A study based on analysis of drug residues in used injection equipment and self-reported information.

BACKGROUND: People who inject drugs (PWID) have a high risk of premature death due to fatal overdoses. Newly emerged fentanyls, much more potent than heroin and other opioids, may increase this risk further. Therefore, precise information on injected drugs is critical to improving prevention strategies. AIMS: This study aimed to analyse drug residues in used injection equipment in order to determine drug and drug combinations and compare and complement findings with self-reported information. METHODS: Used syringes and needles (n=766) were collected at the supervised drug consumption facilities, the needle exchange service and two low-threshold health services for problem drug users in Oslo, Norway. The material was collected every third month from June 2019 to June 2020 and analysed for 64 substances using highly specific analytical methods (ultra-high performance liquid chromatography tandem mass spectrometry). Additionally, a street-recruited sample of PWID was interviewed from 2017 to 2019 regarding their drug injection habits (n=572). RESULTS: Heroin (65.5%) or amphetamines (59.8%), often in combination (30.5%), were commonly detected in drug residues. Other opioids, stimulants or benzodiazepines were rarely detected (6.1%). Fentanyl was detected in only one syringe. Heroin was the most reported drug (77.6% during the past four weeks, 48.3% daily/almost daily), followed by amphetamines (57.5% during the past four weeks, 23.1% daily or almost daily). Injection of methadone, buprenorphine and dissolved tablets was self-reported more frequently than determined in drug residue findings. CONCLUSIONS: Analysis of the injection equipment proved useful as a non-invasive, rapid and accurate means to obtain detailed information on injected drugs in Oslo and supplement traditional PWID survey information.

Tropospheric photolysis rates of the acetaldehyde isotopologues CD3CHO and CD3CDO relative to CH3CHO measured at the European Photoreactor Facility.

Acetaldehyde is a hazardous pollutant found in indoor and ambient air. Acetaldehyde photolysis is pressure- and wavelength-dependent with three distinct product channels. In this study, the photolysis rates of CH3CHO, CD3CDO, and CD3CHO are studied in natural tropospheric conditions using long path FTIR spectroscopy, at the European Photoreactor Facility (EUPHORE) in Valencia, Spain. The average relative photolysis rate as an average of four experiments for the fully deuterated isotopologue is j(CH3CHO)/j(CD3CDO) = 1.75 ± 0.04, and as a result of a single experiment j(CH3CHO)/j(CD3CHO) = 1.10 ± 0.10. These results, combined with our previous determination of j(CH3CHO)/j(CH3CDO) = 1.26 ± 0.03, provide mechanistic insight into the photodissociation dynamics of the photoexcited species. Despite the extensive isotopic scrambling in photoexcited acetaldehyde that has recently been reported, the position of the substitution has a clear effect on the relative photolysis rates.

Relative tropospheric photolysis rates of acetaldehyde and formaldehyde isotopologues measured at the European photoreactor facility.

The photolysis rates of HCHO, DCDO, CH(3)CHO, and CH(3)CDO are studied by long-path FTIR spectroscopy in natural tropospheric conditions at the European Photoreactor Facility (EUPHORE) in Valencia, Spain. Average relative photolysis rates j(HCHO)/j(DCDO) = 3.15 +/- 0.08 and j(CH(3)CHO)/j(CH(3)CDO) = 1.26 +/- 0.03 are obtained from three days of experiments for each reaction in the period June 17 to July 7, 2006.

Experimental and theoretical study of the carbon-13 and deuterium kinetic isotope effects in the Cl and OH reactions of CH3F.

A laser flash photolysis-resonance fluorescence technique has been employed to determine absolute rate coefficients for the CH3F + Cl reaction in N2 bath gas in the temperature range of 200-700 K and pressure range of 33-133 hPa. The data were fitted to a modified Arrhenius expression k(T) = 1.14 x 10(-12) x (T/298)2.26 exp{-313/T}. The OH and Cl reaction rates of (13)CH3F and CD3F have been measured by long-path FTIR spectroscopy relative to CH3F at 298 +/- 2 K and 1013 +/- 10 hPa in purified air. The FTIR spectra were fitted using a nonlinear least-squares spectral fitting method including line data from the HITRAN database and measured infrared spectra as references. The relative reaction rates defined by alpha = k(light)/k(heavy) were determined to be k(OH+CH3F)/k(OH+CD3F) = 4.067 +/- 0.018, k(OH+CH3F)/k(OH+(13)CH3F) = 1.067 +/- 0.006, k(Cl+CH3F)/k(Cl+CD3F) = 5.11 +/- 0.07, and k(Cl+CH3F)/k(Cl+(13)CH3F) = 1.016 +/- 0.006. The carbon-13 and deuterium kinetic isotope effects in the OH and Cl reactions of CH3F have been further investigated by quantum chemistry methods and variational transition state theory.

Nucleophilic identity substitution reactions. The reaction between hydrogen fluoride and protonated alkyl fluorides.

The gas phase reactions between HF and the protonated alkyl fluorides MeFH+, EtFH+, Pr(i)FH+, and Bu(t)FH+ have been studied using ab initio methods. The potential energy profiles for both nucleophilic substitution (S(N)2) and elimination (E2) pathways have been investigated. Both backside Walden inversion and frontside nucleophilic substitution reaction profiles have been generated. Backside substitution is very favourable, but shows relatively little variation with the alkyl group. Frontside substitution reaction barriers are only slightly higher than the barrier for backside substitution for HF + MeFH+, and the difference in barrier heights for frontside and backside displacement seems negligible for the larger alkyl groups. Reaction barrier trends have been analysed and compared with the results of similar studies of the H2O/ROH2+ and NH3/RNH3+ systems (R = Me, Et, Pr(i), and Bu(t)). Compared to the two other classes, protonated fluorides have extreme structures which, with the exception of the Me substrate, are weakly bound complexes between an alkyl cation and HF. The results nourish the idea that nucleophilic substitution reactions are better understood in view of competition between frontside and backside substitution than from the traditional S(N)1/S(N)2 perspective.

Trends in alkyl substituent effects on nucleophilic reactions of carbonyl compounds: gas phase reactions between amines and the methoxy methyl cation.

The reactions of various amines (RNH(2); R = H, CH(3), C(2)H(5) and i-C(3)H(7)) with the methoxy methyl cation (CH(2)OCH(3)(+)) have been investigated using an FT-ICR mass spectrometer, and the experimental results are supplied with ab initio calculations. The amines show clear trends in their reactivities with variable degree of: 1) nucleophilic substitution, 2) addition-elimination and 3) hydride abstraction. In all cases addition-elimination dominates over nucleophilic substitution, and for R not equal H the observed reactions occur at the collisional limit. The potential energy profiles for all three reaction types correlate with the basicities of the amines; the more basic amine-the more favourable is the reaction; in other words: nucleophilicity follows basicity in the gas phase.

Nucleophilic identity substitution reactions. The reaction between ammonia and protonated amines.

The gas phase reactions between NH3 and the protonated amines MeNH3+, EtNH3+, PriNH3+, and Bu(t)nH3+ have been studied by high level ab initio methods. Mass spectrometric experiments yielded no significant reaction products; this result being consistent with the calculated reaction barriers. The potential energy profiles for both nucleophilic substitution (SN2) and elimination (E2) pathways have been investigated. Both back side Walden inversion (SNB) and front side (SNF) nucleophilic reaction profiles have been generated. The SNB reaction barriers are found to be higher for the more alkyl substituted reaction centres. Reaction barrier trends have been analysed and compared with the results of a similar study of the H2O-ROH2+ system (R = Me, Et, Pri, and Bu(t)).

Trends in alkyl substituent effects on nucleophilic reactions of carbonyl compounds: gas phase reactions between ammonia and R1R2COCH3+ oxonium ions.

The reactivity of carbonyl substituted methyl oxonium ions (R1R2COCH3+) towards ammonia has been investigated using an FT-ICR mass spectrometer and ab initio calculations. The monosubstituted ions (R1 = H; R2 = H, CH3, C2H5 and i-C3H7) show different reaction patterns with variable degree of: (1) nucleophilic substitution, (2) addition-elimination and (3) proton transfer, when reacted with ammonia. In all cases addition-elimination dominates over nucleophilic substitution, and the observed reactions are slow. The trends in reactivity are consistent with the alkyl group's electronic properties, as expressed by a single parameter linear or slightly non-linear model.