High Resolution Mass Spectrometric Method Research Articles

Ion Mobility–Mass Spectrometry Approach for the Comparison of Sheep and Goat Milk Lipidomes

In this work, we report an analytical procedure to investigate the lipid compositions of sheep and goat milk. This approach is based on an ion mobility–high-resolution mass spectrometric method to facilitate the identification of complex lipid species and their regiochemistry. A common triacylglycerol profile was observed for sheep and goat milk samples, while a higher abundance of medium-chain fatty acids was observed at the sn-2 position for sheep milk. Furthermore, differences can be also observed in the levels of saturated and unsaturated fatty acids at the sn-2 position. In terms of lipid classes, goat milk showed higher levels of triacylglycerols, phosphatidylinositols and ether-linked phosphatidylethanolamines, while sheep milk showed higher levels of free fatty acids, lysophosphatidylethanolamines, lysophosphocholines and non-hydroxy fatty acid-dihydrosphingosine ceramides when compared with goat milk.

Doping control analysis of trimetazidine in dried blood spot.

Dried blood spot (DBS) analysis has been an inherent part of sports drug testing through the technological advancements of the past decade. Trimetazidine, a non-threshold banned substance, is excreted into urine after a dose of the permitted drug lomerizine. Therefore, a lomerizine-specific metabolite (M6) is analyzed to confirm the origin of trimetazidine in traditional urine analysis. Application studies were conducted to develop an analytical method for trimetazidine applicable to DBS. These studies comprise (1) the effect of different sampling sites on the detection of trimetazidine, (2) the determination of the appropriate trimetazidine level required for DBS analysis, and (3) differentiating between trimetazidine and lomerizine use. A high-resolution mass spectrometric method for detecting trimetazidine in DBS was validated. After oral administration of trimetazidine (n = 7), venous and capillary blood (fingertip and upper arm) were spotted on cellulose paper. Trimetazidine could be identified in DBS in all subjects up to 60 h after administration. The limit of detection was 0.05 ng/ml, and the limit of identification was 0.06 ng/ml, suggesting the minimum required performance level of 0.2 ng/ml. In the fingertip capillary blood, biases of 9.7% (vs. upper arm) and 13.0% (vs. vein) were observed in the trimetazidine intensity; however, there were no concerns in the qualitative analysis. After administering lomerizine (n = 10), the intact lomerizine has a strong peak intensity in blood compared to trimetazidine. Contrary to urine analysis, the M6 was less detectable in blood. Laboratories should confirm intact lomerizine whenever trimetazidine is identified in DBS.

Derivatization to increase the detectability of small peptides in blood serum in the analysis by ESI and MALDI high resolution mass spectrometric methods

This work highlights the efficient approach to highly sensitive determination of dipeptides that can present in biological liquids at very low and trace quantities. The approach involves preliminary derivatization of peptides with tris(2,4,6-trimethoxyphenyl)-methyl carbenium hexafluoroborate followed by ESI and MALDI high-resolution mass spectrometry. Using model dipeptides with various amino acid compositions and sequences, it was shown that the derivatization reaction proceeded smoothly in mild conditions and gave rise to pink-red colored salt derivatives. Ready cations of interest for the analysis are easily desorbed from the salt-derivatives providing strong signals in ESI and MALDI mass spectra and this ensures high sensitivity of the analysis. Another positive aspect is the removal of the target signal from the region of a matrix noise, since the introduced fragment possesses a large mass increment (359 Da). High resolution mass spectrometry, which provides the determination of accurate weights and elemental compositions of ions, was used to reliably detect model dipeptides added to artificial urine and blood serum. A number of these dipeptides was shown to be present in real blood serum collected from volunteers. Collision induced dissociation of precursor cations composed of derivatizing reagent and dipeptide moieties gives rise to characteristic and simple fragmentation mass spectra. A comparison of limits of detection (LOD) measured for non-modified and derivatized dipeptides showed that the latter derivatives provide the highest sensitivity when LOD is determined by using multiple reaction monitoring (MRM) transitions. The suggested derivatization approach was shown to be useful for unambiguous identification of special dipeptides in artificial media and dietary supplements.

MO430MASS-SPECTROMETRIC IDENTIFICATION OF POST-TRANSLATIONAL GUANIDINYLATED PROTEINS IN THE CONTEXT OF SYSTEMIC LUPUS ERYTHEMATOSUS

Abstract Background and Aims With continuous identification of post-translational modified isoforms of proteins, it is becoming increasingly clear that post-translational modifications limit or modify the biological functions of native proteins are majorly involved in development of various chronic disease. This is mostly due to technically advanced molecular identification and quantification methods, mainly based on mass spectrometry. Mass spectrometry has become one of the most powerful tools for the identification of lipids. Method In this study, we used sophisticated high-resolution mass-spectrometric methods to analyze the soluble ligand of receptor Notch-3, namely the Y-box protein (YB)-1, in serum from systemic lupus erythematosus (SLE) patients. In addition, kidneys of lupus-prone (MRL.lpr) mice were analyzed by mass-spectrometric imaging techniques to identify the underlying pathomechanisms. Serum YB-1 was isolated by chromatographic methods, afterwards digested by trypsin and analyzed by matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). The kidneys were fixed in paraffin, then kidney sections were deparaffinized, tryptic digested and analyzed by mass-spectrometric imaging techniques. Mass-spectrometry of extracellular YB-1 in SLE patient serum revealed post-translational guanidinylation of two lysine’s within the highly conserved cold shock domain (CSD) of the YB-1 protein (YB-1-2G). Patients with increased disease activity and those with active renal involvement (lupus nephritis, LN) had a higher degree of dual-guanidinylation within the CSD. Of note, at least one of these modifications was present in all analyzed LN patients, whereas single-guanidinylated YB-1 was present in only one and double modification in none of the control individuals. Mass-spectrometric imaging analyses specifically localized YB-1-2G and increases Notch-3 expression in kidney sections from MRL.lpr mice. Results The data from this study clearly demonstrate the high potential of high-resolution mass spectrometric methods as well as mass spectrometric imaging techniques to identify pathomechanisms of diseases like SLE/LN.

Multidimensional Analytical Characterization of Water-Soluble Organic Aerosols: Challenges and New Perspectives

Water-soluble organic aerosols (OA) are an important component of air particles and one of the key drivers that impact both climate and human health. Understanding the processes involving water-soluble OA depends on how well the chemical composition of this aerosol component is decoded. Yet, obtaining detailed information faces several challenges, including water-soluble OA collection, extraction, and chemical complexity. This review highlights the multidimensional non-targeted analytical strategies that have been developed and employed for providing new insights into the structural and molecular features of water-soluble organic components present in air particles. First, the most prominent high-resolution mass spectrometric methods for near real-time measurements of water-soluble OA and their limitations are discussed. Afterward, a special emphasis is given to the degree of compositional information provided by offline multidimensional analytical techniques, namely excitation–emission (EEM) fluorescence spectroscopy, high-resolution mass spectrometry and two-dimensional nuclear magnetic resonance (NMR) spectroscopy and their hyphenation with chromatographic systems. The major challenges ahead on the application of these multidimensional analytical strategies for OA research are also addressed so that they can be used advantageously in future studies.

The Development of a Liquid Chromatography High-Resolution Mass Spectrometric Method for Apixaban Quantification in Dried Plasma Spots in Parallel Reaction Monitoring Mode

This work aimed at developing and validating a rapid, sensitive, and robust method of liquid chromatography with high-resolution mass spectrometry (LC–HRMS) in parallel reaction monitoring (PRM) mode for apixaban quantification in dried plasma spots (DPSs) with a simple extraction procedure. A 25 µL sample of human plasma was placed onto Whatman 903 Protein Saver Cards and allowed to dry; 3.2 mm diameter disks were cut out from DPSs using a puncher, and 100 µL of a working internal standard solution was added to each sample. After this, they were vortexed on a shaker for 15 min at 800 rpm and 40 °C and quick centrifugation (10,000× g, 10 s), and then the extracts were transferred into a 300 µL vial for LC–HRMS. Data were acquired in PRM mode via detection of all target product ions with 10 ppm tolerance. Total analysis time was 5 min. The LC–HRMS method was validated for the 10–400 ng/mL range with R2 > 0.99. Within this range, intra- and interday variability of precision and accuracy was <10%, and recovery was 69.7–85.1%. Apixaban was stable after brief storage at room temperature, and at 4 °C for up to a month. The method development and validation results proved that this LC–HRMS assay of apixaban in DPSs is selective and robust.

Abstract C065: Breast cancer risk in U.S-born Latina women: potential role of reactive electrophiles

Abstract Background: Breast cancer incidence is lower in foreign-born Latina women compared to U.S.-born Latinas, and the risk increases with younger age at migration. It is only partially known what factors contribute to these risk patterns. Several explanations have been proposed (e.g., changes in reproductive factors, diet, or environmental pollutants), but risk remains higher in U.S.-born Latinas after adjusting for established breast cancer risk factors. The goal of the present study was to find new risk factors that could explain how the migration experience, with its concomitant environmental and lifestyle-changes, affects the risk of breast cancer. Small reactive molecules have long been suspected of causing cancer by binding DNA and causing mutations. Protein adducts result from the presence of these reactive molecules but have the advantage of being easier to measure than DNA adducts. Methods: We measured levels of a panel of 23 human serum albumin (HSA)-Cys34 adducts by high-resolution mass spectrometric methods in selected samples of Latina women from the San Francisco Bay Area Breast Cancer Study for whom serum was available (146 controls and 146 cases, 45% foreign-born). Genetic ancestry was estimated from genome-wide genotypes. To identify adducts that were predictive of foreign-born status and breast cancer diagnosis, we used bootstrapped regularized logistic regression and random forest to rank all adducts and additional covariates such as percent of Indigenous American (IA) ancestry in terms of prediction importance, and then selected variables with higher prediction importance. As a measure of the prediction accuracy of selected variables for the binary outcomes, we calculated a cross-validated area under the receiver operating curve (AUC) estimate using the set of selected adducts and covariates, as well as a corresponding 95% confidence intervals. Results and Conclusions: In a model that included foreign-born status as the dependent variable, all adducts and demographic variables, two adducts were selected as predictors: mass to charge ratio (m/z)=849.07 (addition of S2O3H) and m/z=847.10 (S-methylsulfonylation). Adduct 849.07 had an associated random forest variable importance that was considerably greater than that of any other adduct. This adduct had lower levels in foreign-born Latinas and in Latinas with high IA ancestry. Additionally, adduct 849.07 was the top-ranking variable when breast cancer status was analyzed as the dependent variable. Other variables, including body mass index (BMI), African and IA ancestry, were also selected by the regularized regression as predictive, and together all five variables had a cross-validated AUC estimate of 0.61, 95% CI=(0.55,0.68) when predicting foreign-born status. Our results suggest that adduct 849.07 may be associated with the increased risk of breast cancer observed in U.S-born vs. foreign-born Latinas. More studies are needed to replicate our findings and identify the precursor molecule(s) for this adduct. Citation Format: Silvia J. Serrano-Gómez, Courtney Schiffman, Hasmik Grigoryan, Henrik Carlsson, Sandrine Dudoit, Esther M. John, Stephen M. Rappaport, Laura Fejerman. Breast cancer risk in U.S-born Latina women: potential role of reactive electrophiles [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C065.

Data-Driven UPLC-Orbitrap MS Analysis in Astrochemistry.

Meteorites have been found to be rich and highly diverse in organic compounds. Next to previous direct infusion high resolution mass spectrometry experiments (DI-HR-MS), we present here data-driven strategies to evaluate UPLC-Orbitrap MS analyses. This allows a comprehensive mining of structural isomers extending the level of information on the molecular diversity in astrochemical materials. As a proof-of-concept study, Murchison and Allende meteorites were analyzed. Both, global organic fingerprint and specific isomer analyses are discussed. Up to 31 different isomers per molecular composition are present in Murchison suggesting the presence of ≈440,000 different compounds detected therein. By means of this time-resolving high resolution mass spectrometric method, we go one step further toward the characterization of chemical structures within complex extraterrestrial mixtures, enabling a better understanding of organic chemical evolution, from interstellar ices toward small bodies in the Solar System.

Single-run ultra-high performance liquid chromatography for quantitative determination of ultra-traces of ten popular active pharmaceutical ingredients by quadrupole time-of-flight mass spectrometry after offline preconcentration by solid phase extraction from drinking and river waters as well as treated wastewater

A fit-to-purpose ultra-high performance liquid chromatographic high resolution mass spectrometric method was developed for the ultra-trace analysis of 10 active pharmaceutical ingredients in one chromatographic run as follows: atorvastatin, carbamazepine (CARB), ciprofloxacin (CIPR), clarithromycin (CLAR), diclofenac (DICL), metoprolol (METO), naproxen (NAPR), sitagliptin (SITA), sulfamethoxazole (SULF) and tetracycline. By applying Oasis HLB solid phase extraction cartridges, a 1250-fold enrichment was achieved. For quantitative determination, internal standard calibration was applied. Lower limits of quantification for the analytes were ≤0.025 μg/L. Good linearity was found between 0.01 and 5 μg/L in most cases. Generally, overall recovery for drinking, river and treated wastewater samples spiked with the target analytes at one concentration level comparable with the blank values and another one by one order of magnitude higher was between 80 and 120%. The relative standard deviation values were ≤16%. The proposed method has been applied for the aforementioned water matrices sampled monthly between January and March 2019. Concentration of CARB in drinking water per se was about 0.025 μg/L, confirming the low removal rates during river bank filtration applied for drinking water production. Seven compounds were present in the river water in ≤50 ng/L. Eight compounds were detected at least once from the treated wastewater samples including CARB, DICL, NAPR and SITA in >1 μg/L. Concentration of CARB, DICL, METO, SITA used for chronic affections was almost constant during the monitored time period. To the contrary, concentration of CIPR, CLAR, SULF used for acute infections registered peak values in the same samples taken in winter.

Perspectives on Gender Parity in Bioanalysis: An Interview with Stephanie Cape

Stephanie Cape, is the Director of Bioanalytical Science at Covance, Madison, WI, USA. She received her BS in Chemistry from University of IL- Urbana/Champaign in 2003 and her PhD in Analytical Chemistry from the University of Wisconsin - Madison in 2007. Dr Cape's graduate research was focused on developing high-resolution mass spectrometric methods to enable discovery, characterization, imaging and quantitation of neuropeptides. Stephanie joined the field of regulated bioanalysis as a method development/validation chemist initially at PPD and subsequently at Covance. Within the Covance Bioanalytical team, she has held a variety of leadership roles including oversight of bioanalytical study direction, validation and method development. Additionally, Dr Cape is an active member of the broader scientific community through involvement in multiple industry groups focused on global best practices and innovation in the field of bioanalysis.

UPLC-Orbitrap® Screening for over 35 Drugs of Abuse and Metabolites in Biological Fluids in Under 10 min.

We present a UPLC®-High Resolution Mass Spectrometric method to simultaneously screen for 19 benzodiazepines, 12 opiates, cocaine and three metabolites, and 3 "Z-drug" hypnotic sedatives in both blood and urine specimens. Sample processing consists of a high-speed, high-temperature enzymatic hydrolysis for urine samples followed by a rapid supported liquid extraction (SLE). The combination of ultrahigh-resolution chromatography with high resolution mass spectrometry allows all analytes to be uniquely detected with a 10 min analytical run. Limits of detection for all target analytes are 3ng/mL or better, with only 300μL of specimen used for analysis. The combination of low sample volume with fast processing and analysis makes this method a suitable replacement for immunoassay screening of the targeted drug classes, while providing far superior specificity and better limits of detection than can routinely be obtained by immunoassay.

Two Cases of Non-fatal Intoxication with a Novel Street Hallucinogen: 3-Methoxy-Phencyclidine

3-Methoxy-phencyclidine (3-MeO-PCP) is a structural derivative of the dissociative hallucinogen phencyclidine (PCP). Although PCP toxicity is well documented, little is known about this new psychoactive substance despite being available on the black market even in central Europe. The objective of this case report is to present clinical and laboratory data of analytically confirmed non-fatal intoxication of two subjects with 3-MeO-PCP. A preliminary assessment of potential metabolites excreted into urine was enabled using the liquid chromatography high resolution mass spectrometric method.

Effect of exposure of allethrin based mosquito coil smoke on neurobehavior of male albino rats and protective role of vitamin C

Pyrethrum as well as synthetic pyrethroids like allethrin, resmethrin, phenothrin, tetramethrin, cyfluthrin, cypermethrin, deltamethrin or permethrin are among the insecticides most often used worldwide. With a sensitive and valid gas-chromatographic–high resolution mass spectrometric method, it is possible to detect all pyrethrum and pyrethroid metabolites in one analytical run. Thus, for the first time a background level of trans-chrysanthemumdicarboxylic acid (CDCA) in urine (95th percentile: 0.15 μg/l) as a characteristic, e.g. for a pyrethrum exposure was found. Following a pyrethrum exposure lasting 1 day, CDCA was found in 27 out of 30 subjects with concentrations going up to 54 μg/l urine (mean: 1.1 ± 4.4 μg/l). To obtain information about the elimination kinetics of pyrethrum in humans, urinary excretion of CDCA was investigated in three volunteers after oral intake of 0.3 mg pyrethrin I. CDCA was detected during the first 36 h after intake with elimination being most rapid during the first 4 h (mean elimination half-life: 4.2 h).

Beyond monotherapy: Integrating immunotherapy into current treatment regimens

While we have shown that these urinary metabolites are risk biomarkers for lung cancer in these studies, they are not fully predictive. This is because these biomarkers are mainly measuring exposure but do not take into account the critical metabolic activation step leading to the formation of DNA adducts which cause the multiple mutations observed in lung cancer. Quantitation of DNA adducts is challenging because of their low levels, typically less than 1 adduct per 10 normal bases, and the small amounts of DNA available for studies in living humans. To address this question, we are developing high resolution mass spectrometric methods for quantifying oral cell DNA adducts as a surrogate for DNA adduct formation in the lung. In one recent study, we found remarkably high levels of DNA adducts of tobaccospecific compounds in in the oral mucosa cells of smokers compared to non-smokers. We are also able to quantify formaldehyde-DNA adducts in oral mucosa cells. As mass spectrometric methods for analysis of carcinogen-DNA adducts become increasingly more sensitive and specific, it appears likely that quantitation of a panel of tobacco carcinogen DNA adducts in smokers, leading to identification of susceptible individuals, may be feasible.

Universal mass spectrometric analysis of poly(ionic liquid)s.

We introduce a universal high resolution mass spectrometric method for the analysis of poly(ionic liquid)s (PILs), which belong to the most challenging polyelectrolytes from an analytical perspective, by fusing high resolution collision-induced dissociation (CID)-Orbitrap mass spectrometry (MS) with supercharging agents as well as quadrupole time-of-flight (QToF) MS. The study includes a wide array of hydrophilic halide-containing PILs, which were analyzed in negative mode. The influence of the core structures (based on imidazolium, triazolium, ammonium, phosphonium and pyridinium moieties), and variable styrene-, acrylate- and vinyl-type IL polymers on the ionization behavior is mapped in detail. Variable end group functionalities were introduced via functional chain transfer agents (CTA) in reversible addition-fragmentation chain transfer (RAFT) polymerization to study their behavior during the MS analysis. Furthermore, the demanding class of vinylimidazolium halide IL polymers was investigated. The current contribution thus introduces a new analytical technology platform for an entire polymer class.

Ultra performance liquid chromatography atmospheric pressure photoionization high resolution mass spectrometric method for determination of multiclass pesticide residues in grape and mango juices

A novel analytical method was developed for determination of organochlorine, synthetic pyrethroid, organophosphate and carbamate pesticide residues in fruit juices using ultra performance liquid chromatography–atmospheric pressure photoionization–high resolution mass spectrometry (UPLC–APPI–HRMS). The analytes were extracted from fruit juices by dispersive solid-phase extraction using multi-walled carbon nanotubes (MWCNTs). The analysis was carried out in full scan mode using dual ionization mode of APPI in the mass range of 100–650 units. The limit of detection and limit of quantification values for the pesticides were in the range of 0.025–0.15ngmL−1 and 0.1–0.5ngmL−1 respectively. The matrix effect of the method was found to be low and extraction recoveries were in the range of 60–110%. Some of the real fruits juice samples showed the presence of some pesticides in the range of 6.5–24.8ngL−1.

Biomarker of pyrethrum exposure

Pyrethrum as well as synthetic pyrethroids like allethrin, resmethrin, phenothrin, tetramethrin, cyfluthrin, cypermethrin, deltamethrin or permethrin are among the insecticides most often used worldwide. With a sensitive and valid gas-chromatographic–high resolution mass spectrometric method, it is possible to detect all pyrethrum and pyrethroid metabolites in one analytical run. Thus, for the first time a background level of trans-chrysanthemumdicarboxylic acid (CDCA) in urine (95th percentile: 0.15 μg/l) as a characteristic, e.g. for a pyrethrum exposure was found. Following a pyrethrum exposure lasting 1 day, CDCA was found in 27 out of 30 subjects with concentrations going up to 54 μg/l urine (mean: 1.1 ± 4.4 μg/l). To obtain information about the elimination kinetics of pyrethrum in humans, urinary excretion of CDCA was investigated in three volunteers after oral intake of 0.3 mg pyrethrin I. CDCA was detected during the first 36 h after intake with elimination being most rapid during the first 4 h (mean elimination half-life: 4.2 h).

Simultaneous determination of pyrethroid and pyrethrin metabolites in human urine by gas chromatography–high resolution mass spectrometry

A new developed gas chromatographic–high resolution mass spectrometric method for the sensitive simultaneous determination of trans-chrysanthemumdicarboxylic acid, cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid, cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid, 3-phenoxybenzoic acid and 4-fluoro-3-phenoxybenzoic acid in human urine is presented. These metabolites are biomarkers for an exposure to pyrethrum, allethrin, resmethrin, phenothrin, tetramethrin, cyfluthrin, cypermethrin, deltamethrin or permethrin. Therefore, with the help of this method for the first time a complete assessment of exposure to pyrethroid and pyrethrin insecticides is possible. After acid hydrolysis and extraction with tert-butyl-methyl-ether the residue is derivatized with 1,1,1,3,3,3-hexafluoroisopropanol and analyzed by GC/HRMS in electron impact mode (detection limits < 0.1 μg/l) as well as in negative chemical ionization mode (detection limit < 0.05 μg/l urine).

Automated high resolution mass spectrometry for the synthetic chemist

Exact mass measurement at high resolution is an important tool alongside other spectroscopic methods to help confirm the structure of a novel compound prepared by the synthetic chemist. Exact mass measurement is used in the pharmaceutical industry to confirm the expected empirical formula of a product when problems have been experienced using elemental analysis. Because of the amount of manual intervention necessary when acquiring exact mass measurements, especially when using probe ionization techniques such as fast atom bombardment ionization or electron ionization, this method has been seen to be time consuming and labor intensive for the mass spectrometrist. An automated high resolution mass spectrometric method has been developed at Pfizer Central Research which has streamlined exact mass measurement. The method, which uses electrospray ionization on a double focusing mass spectrometer, is described. The samples are analyzed using a flow injection technique, with sodiated polyethylene glycol present in the mobile phase to provide mass reference peaks. The data are acquired and processed using a macro developed “in house.” This automated technique can process 15–20 samples an hour including data processing and report generation, using very small amounts of compound (∼25 μg), but more importantly it can be left to run unattended overnight. This allows the instrument to be used for more complex experiments during the day when it is important to have a mass spectrometrist present. The results presented here demonstrate that this method gives exact mass measurements within an acceptable limit of 5 ppm, and the variation on one sample, injected 10 times, is not excessively high (−1.8 to +1.6 mDa).

The chemistry of Sr 2+ in association with propanol clusters

A combination of the ‘pick-up’ technique and high resolution mass spectrometric methods have been used to generate and study doubly charged cluster ions of the form [Sr(CH 3CH 2CH 2OH) n] 2+. As a result of charge transfer, no ions are observed for n = 1 and the parent ion distribution rises to a sharp maximum at n = 4, suggesting a first solvation shell. For n = 2 the parent ion is observed to undergo charge transfer via unimolecular (metastable) decay to give Sr +OH(C 3H 7OH) as the principal fragment with a significant fraction of the Coulomb energy appearing as kinetic energy release. Larger parent ions exhibit propanol loss as the dominant metastable decay channel. In contrast, the collisional activation of [Sr(C 3H 7OH) n] 2+ ions for n > 2 is observed to promote extensive fragmentation accompanied by Coulomb explosion in which charged separation follows the breaking of covalent bonds. However, in some instances the measured kinetic energy releases for the latter process are very much lower than expected and it is suggested that either excess energy is being carried away by very light fragments, e.g. H and H 2, or that the energy available is low due to small differences in the ionisation energies of the product ions. Reaction products observed for [Sr(C 3H 7OH) n] 2+ ions can be accounted for by assuming anion transfer processes.