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1.
Anal Chim Acta ; 1315: 342757, 2024 Aug 01.
Article in English | MEDLINE | ID: mdl-38879205

ABSTRACT

BACKGROUND: Chlorinated paraffins (CPs) are industrial chemicals categorised as persistent organic pollutants because of their toxicity, persistency and tendency to long-range transport, bioaccumulation and biomagnification. Despite having been the subject of environmental attention for decades, analytical methods for CPs still struggle reaching a sufficient degree of accuracy. Among the issues negatively impacting the quantification of CPs, the unavailability of well-characterised standards, both as pure substances and as matrix (certified) reference materials (CRMs), has played a major role. The focus of this study was to provide a matrix CRM as quality control tool to improve the comparability of CPs measurement results. RESULTS: We present the process of certification of ERM®-CE100, the first fish reference material assigned with certified values for the mass fraction of short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs, respectively). The certification was performed in accordance with ISO 17034:2016 and ISO Guide 35:2017, with the value assignment step carried out via an intercomparison of laboratories of demonstrated competence in CPs analysis and applying procedures based on different analytical principles. After confirmation of the homogeneity and stability of the CRM, two certified values were assigned for SCCPs, depending on the calibrants used: 31 ± 9 µg kg-1 and 23 ± 7 µg kg-1. The MCCPs certified value was established as 44 ± 17 µg kg-1. All assigned values are relative to wet weight in the CRM that was produced as a fish paste to enhance similarity to routine biota samples. SIGNIFICANCE AND NOVELTY: The fish tissue ERM-CE100 is the first matrix CRM commercially available for the analysis of CPs, enabling analytical laboratories to improve the accuracy and the metrological traceability of their measurements. The certified CPs values are based on results obtained by both gas and liquid chromatography coupled with various mass spectrometric techniques, offering thus a broad validity to laboratories employing different analytical methods and equipment.


Subject(s)
Hydrocarbons, Chlorinated , Paraffin , Reference Standards , Hydrocarbons, Chlorinated/analysis , Paraffin/analysis , Paraffin/chemistry , Animals , Fishes
2.
Heliyon ; 9(6): e16987, 2023 Jun.
Article in English | MEDLINE | ID: mdl-37346323

ABSTRACT

Chlorinated paraffins (CPs) are a notoriously known class of compounds that stand amongst the most wide-spread persistent organic pollutants. Therefore, their reliable, repeatable, and reproducible quantitative analysis using well-defined reference standards is of utmost importance. In view of the increasing demand for constitutionally and stereochemically defined CP standards, we have synthesized a stereoisomeric mixture of 3,4,7,8-tetrachlorodecane. One stereoisomer - (3R,4R,7S,8S)-3,4,7,8-tetrachlorodecane was separated from the mixture, and enriched fractions of residual stereoisomers were achieved through crystallisation of the residual mother liquors. The molecular structure of the single isolated stereoisomer was confirmed through single-crystal X-ray crystallographic data. One fraction of 3,4,7,8-tetrachlorodecane stereoisomers was successfully separated on a chiral stationary phase using supercritical fluid chromatography hyphenated to mass spectrometry (column: Chiral ART Amylose-C; mobile phase: CO2/MeOH (96/4 v/v) with 0.1% diethylamine). The reported separation of stereoisomers is unprecedented in CP analysis so far.

3.
Anal Bioanal Chem ; 415(15): 2907-2919, 2023 Jun.
Article in English | MEDLINE | ID: mdl-36947170

ABSTRACT

Reference materials (RMs) are vital tools in the validation of methods used to detect environmental pollutants. Microplastics, a relatively new environmental pollutant, require a variety of complex approaches to address their presence in environmental samples. Both interlaboratory comparison (ILC) studies and RMs are essential to support the validation of methods used in microplastic analysis. Presented here are results of quality assurance and quality control (QA/QC) performed on two types of candidate microplastic RMs: dissolvable gelatin capsules and soda tablets. These RMs have been used to support numerous international ILC studies in recent years (2019-2022). Dissolvable capsules containing polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyethylene (PE), and polystyrene (PS), in different size fractions from 50 to 1000 µm, were produced for one ILC study, obtaining relative standard deviation (RSD) from 0 to 24%. The larger size fraction allowed for manual addition of particles to the capsules, yielding 0% error and 100% recovery during QA/QC. Dissolvable capsules were replaced by soda tablets in subsequent ILC studies and recovery test exercises because they were found to be a more reliable carrier for microplastic RMs. Batches of soda tablets were produced containing different single and multiple polymer mixtures, i.e., PE, PET, PS, PVC, polypropylene (PP), and polycarbonate (PC), with RSD ranging from 8 to 21%. Lastly, soda tablets consisting of a mixture of PE, PVC, and PS (125-355 µm) were produced and used for recovery testing during pretreatment of environmental samples. These had an RSD of 9%. Results showed that soda tablets and capsules containing microplastics >50 µm could be produced with sufficient precision for internal recovery tests and external ILC studies. Further work is required to optimize this method for smaller microplastics (< 50 µm) because variation was found to be too large during QA/QC. Nevertheless, this approach represents a valuable solution addressing many of the challenges associated with validating microplastic analytical methods.

4.
Chemosphere ; 308(Pt 3): 136312, 2022 Dec.
Article in English | MEDLINE | ID: mdl-36096309

ABSTRACT

A new simple method for chlorine percentage calculations (method C), from proton nuclear magnetic resonance (1H NMR) spectroscopy, has been established and applied to an industrial chlorinated paraffin (CP) mixture and 13 single-chain CPs of known carbon chain lengths. Two modified methods (method A and B), originating from the work of Sprengel et al., have been utilized on the same single-chain mixtures. All samples were analysed by 1H NMR and two-dimensional heteronuclear quantum coherence (HSQC) for this purpose. All three methods worked well for medium chlorinated (45-55% Cl) single-chain mixtures of known carbon chain lengths. Method A yielded the best result for mixtures of lower chlorine content (<45% Cl), method C gave better estimations for higher chlorine contents (>55% Cl). Compared to Mohr's titration, method A showed a deviation of 0.7-7.8% (3.6% average), method B 4.1-11.3% (7.0% average) and method C 0.6-11.6% (5.2% average), for all 13 single-chain mixtures. The new method C is the only method that could be applied for determining the chlorine percentage of industrial mixtures of multiple, unknown chain lengths.


Subject(s)
Hydrocarbons, Chlorinated , Paraffin , Carbon/analysis , China , Chlorine/chemistry , Environmental Monitoring , Hydrocarbons, Chlorinated/analysis , Magnetic Resonance Spectroscopy , Paraffin/analysis , Protons
5.
Molecules ; 20(4): 5329-45, 2015 Mar 25.
Article in English | MEDLINE | ID: mdl-25816077

ABSTRACT

The illegal use of opiates and cocaine is a challenge world-wide, but some derivatives are also valuable pharmaceuticals. Reference samples of the active ingredients and their metabolites are needed both for controlling administration in the clinic and to detect drugs of abuse. Especially, (13)C-labeled compounds are useful for identification and quantification purposes by mass spectroscopic techniques, potentially increasing accuracy by minimizing ion alteration/suppression effects. Thus, the synthesis of [acetyl-(13)C4]heroin, [acetyl-(13)C4-methyl-(13)C]heroin, [acetyl-(13)C2-methyl-(13)C]6-acetylmorphine, [N-methyl-(13)C-O-metyl-(13)C]codeine and phenyl-(13)C6-labeled derivatives of cocaine, benzoylecgonine, norcocaine and cocaethylene was undertaken to provide such reference materials. The synthetic work has focused on identifying (13)C atom-efficient routes towards these derivatives. Therefore, the (13)C-labeled opiates and cocaine derivatives were made from the corresponding natural products.


Subject(s)
Analgesics, Opioid/chemical synthesis , Biological Products/analysis , Cocaine/analogs & derivatives , Morphine/chemical synthesis , Urinalysis/standards , Analgesics, Opioid/chemistry , Analgesics, Opioid/metabolism , Analgesics, Opioid/urine , Biological Products/urine , Carbon-13 Magnetic Resonance Spectroscopy , Cocaine/chemical synthesis , Codeine/chemical synthesis , Codeine/chemistry , Heroin/chemical synthesis , Heroin/chemistry , Humans , Molecular Structure , Morphine/chemistry , Morphine Derivatives/urine , Substance Abuse Detection/standards
6.
Molecules ; 19(9): 13526-40, 2014 Sep 01.
Article in English | MEDLINE | ID: mdl-25255754

ABSTRACT

(-)-∆9-Tetrahydrocannabinol is the principal psychoactive component of the cannabis plant and also the active ingredient in some prescribed drugs. To detect and control misuse and monitor administration in clinical settings, reference samples of the native drugs and their metabolites are needed. The accuracy of liquid chromatography/mass spectrometric quantification of drugs in biological samples depends among others on ion suppressing/alteration effects. Especially, 13C-labeled drug analogues are useful for minimzing such interferences. Thus, to provide internal standards for more accurate quantification and for identification purpose, synthesis of [13C4]-∆9-tetrahydro-cannabinol and [13C4]-11-nor-9-carboxy-∆9-tetrahydrocannabinol was developed via [13C4]-olivetol. Starting from [13C4]-olivetol the synthesis of [13C4]-11-nor-9-carboxy-∆9-tetrahydrocannabinol was shortened from three to two steps by employing nitromethane as a co-solvent in condensation with (+)-apoverbenone.


Subject(s)
Chromatography, Liquid/methods , Dronabinol/chemical synthesis , Tandem Mass Spectrometry/methods , Carbon Isotopes , Dronabinol/analogs & derivatives
7.
J Chromatogr A ; 1344: 83-90, 2014 May 30.
Article in English | MEDLINE | ID: mdl-24780257

ABSTRACT

Stable isotope-labeled internal standards (SIL-ISs) are often used when applying liquid chromatography-tandem mass spectrometry (LC-MS/MS) to analyze for legal and illegal drugs. ISs labeled with (13)C, (15)N, and (18)O are expected to behave more closely to their corresponding unlabeled analytes, compared with that of the more classically used (2)H-labeled ISs. This study has investigated the behavior of amphetamine, (2)H3-, (2)H5, (2)H6-, (2)H8-, (2)H11-, and (13)C6-labeled amphetamine, during sample preparation by liquid-liquid extraction and LC-MS/MS analyses. None or only minor differences in liquid-liquid extraction recoveries of amphetamine and the SIL-ISs were observed. The chromatographic resolution between amphetamine and the (2)H-labeled amphetamines increased with the number of (2)H-substitutes. For chromatographic studies we also included seven additional (13)C6-amphetamines and their analytes. All the (13)C6-labeled ISs were co-eluting with their analytes, both when a basic and when an acidic mobile phase were used. MS/MS analyses of amphetamine and its SIL-ISs showed that the ISs with the highest number of (2)H-substitutes required more energy for fragmentation in the collision cell compared with that of the ISs with a lower number. The findings, in this study, support those of previous studies, showing that (13)C-labeled ISs are superior to (2)H-labeled ISs, for analytical purposes.


Subject(s)
Amphetamines/analysis , Amphetamine/analysis , Amphetamine-Related Disorders/diagnosis , Carbon Isotopes , Chromatography, Liquid/methods , Chromatography, Liquid/standards , Deuterium , Liquid-Liquid Extraction , Reference Standards , Reproducibility of Results , Substance Abuse Detection/methods , Tandem Mass Spectrometry/methods , Tandem Mass Spectrometry/standards
8.
J Labelled Comp Radiopharm ; 57(5): 378-87, 2014 May 15.
Article in English | MEDLINE | ID: mdl-24634286

ABSTRACT

The availability of high-quality (13)C-labelled internal standards will improve accurate quantification of narcotics and drugs in biological samples. Thus, the synthesis of 10 [(13)C6]-labelled phenethylamine derivatives, namely amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxy-N-ethylamphetamine, 4-methoxyamphetamine, 4-methoxymethamphetamine, 3,5-dimethoxyphenethylamine 4-bromo-2,5-dimethoxyphenethylamine and 2,5-dimethoxy-4-iodophenethylamine, have been undertaken. [(13)C6]-Phenol proved to be an excellent starting material for making (13)C-labelled narcotic substances in the phenethylamine class, and a developed Stille-type coupling enabled an efficient synthesis of the 3,4-methylenedioxy and 4-methoxy derivatives. The pros and cons of alternative routes and transformations are also discussed. The [(13)C6]-labelled compounds are intended for use as internal standards in forensic analysis, health sciences and metabolomics studies by gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry.


Subject(s)
Carbon Isotopes/analysis , Carbon Isotopes/chemistry , Mass Spectrometry/methods , Phenethylamines/analysis , Phenethylamines/chemistry , Radiopharmaceuticals/chemical synthesis , Substance Abuse Detection/methods , Drug Design , Isotope Labeling
9.
Magn Reson Chem ; 48(12): 951-4, 2010 Dec.
Article in English | MEDLINE | ID: mdl-20882514

ABSTRACT

The full (1)H and (13)C NMR chemical shift assignment of 2α-methyl-17α(H),21ß(H)-hopane is presented. This compound is formed in mature sediments from biogenic sources of 2ß-methyl-17ß(H),21ß(H)-hopanoids, which include several cyanobacteria. In addition, full (1)H and (13)C NMR chemical shift data of all four 17,21 isomers of 3ß-methylhopane have been assigned. The thermodynamically most stable 3ß-configuration corresponds to that found in bacterial sources. The data presented here suggest minor corrections to the (13)C chemical assignments reported earlier for 17α(H)-hopanes. Moreover, spectral evidence indicates an unexpected ring-D boat conformation of 17α(H),21α(H)-hopanes, which may serve to explain the steric strain reported for this isomer.


Subject(s)
Methane , Triterpenes/chemistry , Magnetic Resonance Spectroscopy , Methane/chemistry , Molecular Structure , Thermodynamics
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