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Each year, Bioanalysis and Bioanalysis Zone run the Young Investigator Award to identify and reward promising early-career researchers in our community. This year, 12 young scientists were nominated for the award and their profiles have been featured on our sister website, Bioanalysis Zone. Our Advisory Panel helped us narrow down the nominees to the five most exceptional candidates.

A thermal desorption unit has been interfaced to an electrospray ionization-ion mobility-time-of-flight mass spectrometer. The interface was evaluated using a mixture of six model volatile organic compounds which showed detection limits of1 ng sample loaded onto a thermal desorption tube packed with Tenax, equivalent to sampled concentrations of 4 microg L(-1). Thermal desorption profiles were observed for all of the compounds, and ion mobility-mass spectrometry separations were used to resolve the probe compound responses from each other. The combination of temperature programmed thermal desorption and ion mobility improved the response of selected species against background ions. Analysis of breath samples resulted in the identification of breath metabolites, based on ion mobility and accurate mass measurement using siloxane peaks identified during the analysis as internal lockmasses.

A two-stage thermal desorption/secondary electrospray ionization/time-of-flight mass spectrometry for faster targeted breath profiling has been studied. A new secondary electrospray ionization (SESI) source was devised to constrain the thermal desorption plume and promote efficient mixing in the ionization region. Further, a chromatographic pre-separation stage was introduced to suppress interferences from siloxanes associated with thermal desorption profiles of exhaled breath samples.In vitro tests with 5-nonanone indicated an increased sensitivity and a lowered limit-of-detection, both by a factor of ~4, the latter to an on-trap mass of 14.3 ng, equivalent to a sampled breath concentration of 967 pptv. Analysis of the mass spectrometric responses from 20 breath samples acquired sequentially from a single participant indicated enhanced reproducibility (reduced relative standard deviations (RSD) for 5-nonanone, benzaldehyde and 2-butanone were 28 %, 16% and 14% respectively. The corresponding values for an open SESI source were that 5-nonanone was not detected, with %RSD of 39% for benzaldehyde and 31% for 2-butanone).The constrained source with chromatographic pre-separation resulted in an increase in the number of detectable volatile organic compounds (VOCs) from 260 mass spectral peaks with an open SESI source to 541 peaks with the constrained source with pre-separation. Most of the observed VOCs were present at trace levels, at less than 2.5% of the intensity of the base peak.Seventeen 2.5 dm(3) distal breath samples were collected from asthma patients and healthy controls respectively, and subjected to comparative high-throughput screening using thermal desorption/SESI/time-of-flight mass spectrometry (TD-SESI-ToFMS). Breath metabolites were detected by using a background siloxane ion (hexamethylcyclotrisiloxane m/z 223.0642) as an internal lockmass. Eleven breath metabolites were selected from the breath research literature and successfully targeted. These data reinforce the proposition that TD-SESI-MS has potential for development as a rapid screening method for disease stratification and targeted metabolism profiling.

Background: In-community non-invasive identification of asthma-specific volatile organic compounds (VOCs) in exhaled breath presents opportunities to characterize phenotypes, and monitor disease state and therapies. The feasibility of breath sampling with children and the preliminary identification of childhood asthma markers were studied. Method: End-tidal exhaled breath was sampled (2.5 dm3) from 11 children with asthma and 12 healthy children with an adaptive breath sampler. VOCs were collected onto a Tenax®/Carbotrap hydrophobic adsorbent trap, and analyzed by GC–MS. Classification was by retention-index and mass spectra in a ‘breath matrix‘ followed by multivariate analysis. Results: A panel of eight candidate markers (1-(methylsulfanyl)propane, ethylbenzene, 1,4-dichlorobenzene, 4-isopropenyl-1-methylcyclohexene, 2-octenal, octadecyne, 1-isopropyl-3-methylbenzene and 1,7-dimethylnaphtalene) were found to differentiate between the asthmatic and healthy children in the test cohort with complete separation by 2D principal components analysis (2D PCA). Furthermore, the breath sampling protocol was found to be acceptable to children and young people. Conclusion: This method was found to be acceptable for children, and healthy and asthmatic individuals were distinguished on the basis of eight VOCs at elevated levels in the breath of asthmatic children.

The exhaled breath is rich in a wide range of volatile organic compounds with the potential to provide readily accessible biomarkers for metabolic activity in the body as a result of normal or abnormal/disease processes. Exhaled breath samples from five healthy volunteers have been analyzed by thermal desorption GC–MS using electron impact and chemical ionization. A total of eight compounds: 2-propenoic acid; 2-methyl, methyl ester; toluene; hexanal; 1,4-cyclohexadiene, 1-methyl-4-(1methlethyl); phenol; nonanal; dodecane and indole, have been evaluated to establish differences in selectivity and sensitivity using these two mechanisms of ionization. The combination of both electron impact and chemical ionization profiles could prove valuable when prospecting for breath-derived biomarkers as they result in complementary information that aids the identification of unknown components.

5-Oxoproline (5-OP; pyroglutamate) is an intermediate in the biosynthesis of the endogenous tripeptide glutathione and has been seen to be elevated in the biofluids and tissues of rats following the administration of glutathione-depleting hepatotoxic xenobiotics such as acetaminophen (paracetamol), bromobenzene and ethionine. As 5-OP is a potential biomarker for hepatotoxicity HPLC-MS/MS methods have been developed for its quantification in in vitro cell culture media and rat plasma. For the cell culture media the lower limit of quantification (LLOQ), defined as the lowest concentration on the calibration curve, was 10 ng/ml. Minimal carry over was observed for cell culture media between injections (less than 5% at all concentrations examined), precision and accuracy were generally better than 20% for within and between day analyses. For rat plasma a LLOQ of 50 ng/ml was obtained. Carry over for plasma was less than 5% for all concentrations, within and between batch accuracy and precision were generally better than 20%. The methods were linear for both sample types from the LLOQ up to 1. μg/ml. For samples obtained from rats subjected to chronic administration of the hepatotoxin methapyrilene, concentrations of 5-OP were not observed to increase significantly at any time point compared to controls. 5-OP was also determined in the culture media of human liver epithelial (THLE) cells transfected with cytochrome P450 2E1 (THLE-2E1). Following exposure of THLE-2E1 cells to acetaminophen, large increases in the concentrations of 5-OP were observed, which correlated with reduced cellular glutathione content and with cell toxicity. These results show that LC-MS/MS can be used to perform rapid, sensitive, and quantitative determination of 5-OP in vivo and in vitro and will enable additional investigations into the utility of 5-OP as a biomarker of liver drug-induced liver injury. © 2011 Elsevier B.V.

localization of the colonoscope tip may not be reliable. We aimed to assess accuracy of colonoscopist localization of polyps at the time of colonoscopy and determine if patient, procedure or colonoscopist variables influence the accuracy of localization. Methods: We conducted a prospective observational study in consecutive patients presenting for elective, outpatient colonoscopy at an academic center. All procedures were performed by board-certified colonoscopists. Polyps found during colonoscope withdrawal were included. The endoscopic location of each polyp was reported by the colonoscopist at the time of resection and prospectively recorded. Magnetic endoscope imaging (ScopeGuide, Olympus, Japan) was used to generate a reference standard for polyp location. For each procedure, a ScopeGuide image of the instrument location on insertion, caecal intubation and during polypectomy was prospectively obtained. Colonoscopists were blinded to the ScopeGuide image. Three separate expert colonoscopists, blinded to the endoscopist’s assessment of polyp location, independently reviewed the ScopeGuide images to obtain a reference standard for polyp location (Cronbach alpha 0.98). We assessed the accuracy of colonoscopist polyp localisation using the ScopeGuide-derived reference standard. We assessed extent of deviation between colonoscopist location and ScopeGuide location, by dividing the colon in 18 segments from caecum to distal rectum. Results: A total of 282 polyps were resected in 155 patients by 16 colonoscopists. Overall accuracy of polyp localization was 85%. Accuracy varied significantly (p!0.001) by colonic segment: caecum 100%, ascending 77%, transverse 82%, descending 56%, sigmoid 90%, rectum 95%. There was no significant deviation between ScopeGuide location and colonoscopist location for polyps located in the distal sigmoid and rectum (mean deviation 0.3 segments, range 0-3 segments, pZ0.32). There was significant deviation between ScopeGuide location and colonoscopist location from caecum to mid-sigmoid colon (mean deviation 0.8, range 0-6 segments, p!0.001). Extent of deviation between actual and predicted location was not influenced by patient sex, age, body mass index, surgical history, bowel preparation or years of colonoscopy experience. Conclusion: Accuracy of localization of polyps is imprecise, and affected by position within the colon. Methods to improve lesion localization at colonoscopy should be studied.