Scope and limitations of a general unknown screening by gas chromatography-mass spectrometry in acute poisoning

Merits and Limitations of Radical vs. Nonradical Pathways in Persulfate-Based Advanced Oxidation Processes

Urbanization and industrialization have exerted significant adverse effects on water quality, resulting in a growing need for reliable and eco-friendly treatment technologies. Persulfate (PS)-based advanced oxidation processes (AOPs) are emerging as viable technologies to treat challenging industrial wastewaters or remediate groundwater impacted by hazardous wastes. While the generated reactive species can degrade a variety of priority organic contaminants through radical and nonradical pathways, there is a lack of systematic and in-depth comparison of these pathways for practical implementation in different treatment scenarios. Our comparative analysis of reaction rate constants for radical vs. nonradical species indicates that radical-based AOPs may achieve high removal efficiency of organic contaminants with relatively short contact time. Nonradical AOPs feature advantages with minimal water matrix interference for complex wastewater treatments. Nonradical species (e.g., singlet oxygen, high-valent metals, and surface activated PS) preferentially react with contaminants bearing electron-donating groups, allowing enhancement of degradation efficiency of known target contaminants. For byproduct formation, analytical limitations and computational chemistry applications are also considered. Finally, we propose a holistically estimated electrical energy per order of reaction (EE/O) parameter and show significantly higher energy requirements for the nonradical pathways. Overall, these critical comparisons help prioritize basic research on PS-based AOPs and inform the merits and limitations of system-specific applications.

Comparison of in-source collision-induced dissociation and beam-type collision-induced dissociation of emerging synthetic drugs using a high-resolution quadrupole time-of-flight mass spectrometer

In-source collision-induced dissociation (CID) is commonly used with single-stage high-resolution mass spectrometers to gather both a molecular formula and structural information through the collisional activation of analytes with residual background gas in the source region of the mass spectrometer. However, unlike tandem mass spectrometry, in-source CID does not involve an isolation step prior to collisional activation leading to a product ion spectrum composed of fragment ions from any analyte present during the activation event. This work provides the first comparison of in-source CID and beam-type CID spectra of emerging synthetic drugs on the same instrument to understand the fragmentation differences between the two techniques and to contribute to the scientific foundations of in-source CID. Electrospray ionization-quadrupole time-of-flight (ESI-Q-TOF) mass spectrometry was used to generate product ion spectra from in-source CID and beam-type CID for a series of well-characterized fentanyl analogs and synthetic cathinones. A comparison between the fragmentation patterns and relative ion abundances for each technique was performed over a range of fragmentor offset voltages for in-source CID and a range of collision energies for beam-type CID. The results indicate that large fragmentor potentials for in-source CID tend to favor higher energy fragmentation pathways that result in both kinetically favored pathways and consecutive neutral losses, both of which produce more abundant lower mass product ions relative to beam-type CID. Although conditions can be found in which in-source CID and beam-type CID provide similar overall spectra, the in-source CID spectra tend to contain elevated noise and additional chemical background peaks relative to beam-type CID.

Taste and/or Odour Disturbances in Pediatric Patients Undergoing IV Flush with Normal Saline Administered by Prefilled Syringe

BACKGROUND

At the Children's Hospital of Eastern Ontario, more than 6000 inpatients per year undergo IV saline flushes by prefilled syringe to assess and maintain patency of IV tubing. In studies involving adults, it has been reported that volatile substances may leach from syringe materials into the saline, leading to taste and/or odour disturbances.

OBJECTIVE

To determine the incidence of taste and/or odour disturbances in pediatric patients after flushing of IV tubing with 0.9% sodium chloride (normal saline [NS]) from prefilled syringes.

METHODS

Inpatients aged 5-18 years who had undergone routine flushing of central or peripheral IV tubing with commercially available prefilled NS syringes were interviewed. Children aged 5-10 years used a visual hedonic scale to rate taste and odour sensations, and those aged 11-18 years used a numeric rating scale.

RESULTS

During the study period (April to July 2011), a total of 104 pediatric inpatients (21 aged 5-10 years and 83 aged 11-18 years) underwent NS flushing of central (10 patients [10%]) or peripheral (94 patients [90%]) tubing. For 100 of these patients, BD Posiflush NaCl 0.9% 10-mL sterile prefilled syringes were used, and for 4 patients BD Saline XS NaCl 0.9% 10-mL sterile prefilled syringes were used. Taste and/or odour disturbances were reported by 76 (73%) of the patients. Twelve patients described more than one taste or odour sensation. Taste and odour disturbances were detected by children in both age groups.

CONCLUSIONS

Flushing of IV tubing with prefilled NS syringes resulted in taste and/or odour disturbances in a pediatric population.

Performance evaluation of three liquid chromatography mass spectrometry methods for broad spectrum drug screening

BACKGROUND

Liquid chromatography-mass spectrometry (LC-MS) and tandem LC-MS (LC-MS/MS) are increasingly used in toxicology laboratories as a complementary method to gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-ultraviolet detection (LC-UV) for comprehensive drug screening (CDS). This study was designed to characterize the sensitivity and specificity of three LC-MS(/MS) vendor-supplied methods for targeted CDS and identify the current limitations associated with the use of these technologies.

METHODS

Five methods for broad spectrum CDS, including LC-UV (REMEDi), full scan GC-MS, LC-MS (ZQ-Mass Detector with MassLynx-software), LC-QTRAP-MS/MS (3200-QTRAP with Cliquid-software) and LC-LIT-MS/MS (LXQ Linear Ion Trap with ToxID-software) were evaluated based on their ability to detect drugs in 48 patient urine samples.

RESULTS

The tandem MS methods identified 15% more drugs than the single stage MS or LC-UV methods. Use of two broad spectrum screening methods identified more drugs than any single system alone. False negatives and false positives generated by the LC-MS(/MS) software programs were identified upon manual review of the raw data.

CONCLUSIONS

The LC-MS/MS methods detected a broader menu of drugs; however, it is essential to establish manual data review criteria for all LC-MS(/MS) drug screening methods. Use of an EI-GC-MS and ESI-LC-MS/MS combination for targeted CDS may be optimal due to the complementary nature of the chromatographic and ionization techniques.

Death due to ingestion of nicotine-containing solution: case report and review of the literature

Nicotine, a lipid-soluble alkaloid obtained from the dried leaves of Nicotiana, is most frequently encountered in tobacco products for smoking, chewing or sniffing as well as in a limited number of pesticides. Though nicotine is one of the most toxic drugs of abuse, it has rarely led to fatalities. Sudden death can be caused by cardiovascular arrest, respiratory muscle paralysis and/or central respiratory failure. A 42-year-old man was found dead by his wife. He was lying on the floor, next to a box containing many empty bottles of beer and vodka. Some labeled chemical bottles found at the scene contained various substances, including nicotine and brucine. Gross examination of the organs at autopsy revealed no specific findings. The toxicological examination failed to disclose any lethal toxic agents other than a high concentration of nicotine and its primary metabolite cotinine in femoral venous blood (2.2 microg/mL). Blood alcohol was determined to be 2.1 g/L in femoral venous blood. Only a paucity of fatal cases of nicotine poisoning has been reported in the literature so far.

Evaluation of an improved general unknown screening procedure using liquid chromatography-electrospray-mass spectrometry by comparison with gas chromatography and high-performance liquid-chromatography--diode array detection

This paper presents an improved, comprehensive liquid chromatography-electrospray-mass spectrometry (LC-ES-MS) general unknown screening (GUS) procedure for drugs and toxic compounds and its comparison with conventional techniques in routine laboratory conditions. Chromatographic separation involved an X-TERRA MS C18, 3.5 microm (100 mm x 1 mm i.d.) column together with a 25-min long gradient of acetonitrile in pH 3, 2 mM ammonium formate delivered at a 50 microl/min flow rate. Two different in-source collision-induced dissociation voltages were alternated, both in the positive and in the negative ion modes. Reconstructed spectra were then obtained in both polarities by adding up spectra obtained with low and high energy, resulting in spectra presenting a sufficient number of specific fragment ions for unambiguous and fast identification of compounds. Two large mass spectral libraries of drugs and toxic compounds were built and an efficient automated signal processing, library searching and report editing algorithm developed. Using a common, efficient solid-phase extraction procedure, this LC-ES-MS technique was compared to GC-MS and HPLC-DAD GUS procedures for the identification of a priori unknown compounds in 51 serum samples consecutively sent to the laboratory for GUS. The present LC-MS method identified 75% of the compounds contained in these samples (versus 66% for GC-MS and 71% for HPLC-DAD), including 8% that the other two techniques failed to identify (versus 8% for GC-MS and 9.5% for HPLC-DAD). Therefore, it is complementary to GC-MS and/or HPLC-DAD and helps enlarge the range of drugs detected in clinical toxicology. It could be useful as well in forensic toxicology to confirm a positive result, as 38% of all the compounds were detected by the three techniques and 36% by two of them.

Liquid chromatography-mass spectrometry: potential in forensic and clinical toxicology

A relatively limited number of papers concerning applications of liquid chromatography-mass spectrometry (LC-MS) to forensic or clinical toxicology, or analytical methods directly applicable to these topics have been published so far, but their number have greatly increased in the past two years, probably due to technical improvements and to a decrease in the price of such instruments. After a brief presentation and exemplary applications of the interfaces and/or sources proposed in the past for coupling HPLC to mass spectrometry (direct liquid inlet, moving belt, fast atom bombardment and thermospray interfaces), this paper describes electrospray-type and atmospheric pressure chemical ionisation interfaces and their most recent applications in forensic or clinical toxicology. In a third section, the different LC-MS solutions proposed for typical applications in human toxicology, such as the determination of morphine metabolites, LSD and its metabolites and corticosteroids in blood or urine, are reviewed in detail in order to highlight the strengths and weaknesses of each ionisation device and/or analytical method. The last section envisages the new analytical fields opened up by LC-MS in toxicology, regarding mainly peptides, proteins and large molecules, as well as the possible use of LC-MS as a complement to GC-MS for "general unknown" screenings; it also deals with the perspectives concerning technical improvements in ionisation interfaces/sources or mass spectrometers, as well as in sample preparation and liquid chromatography techniques applied to this type of coupling. Though LC-MS is still a relatively new technique in toxicology, on taking into consideration its success so far and owing to the simplification of instruments and concept handling thanks to user-friendly software, it is the authors' opinion that it will become a major success in analytical toxicology in the next few years.

Screening for drugs in serum by electrospray ionization/collision-induced dissociation and library searching

Factors influencing in-source collision-induced dissociation (ESI/CID) of organic molecules in a Perkin-Elmer/SCIEX ionspray source have been investigated. Breakdown curves of four drugs and organic compounds were acquired by monitoring the intensities of MH+ and specific fragment ions while ramping the orifice voltage. Haloperidol, diazepam, 1,4-acetamido-acetoxybenzene and diacetamido-1,2-benzene were found to be substances with characteristic breakdown curves, with maximums and points of intersection at orifice voltages between 20 and 70 V. The breakdown curves of haloperidol were used for comparison of ESI/CID with ionspray and turboionspray sources on three PE/SCIEX-API instruments. Using standardized source parameters and mass resolution, very similar fragmentation graphs were obtained for haloperidol with all instruments. Infusion of varying concentrations of haloperidol (0.1 to 10 micrograms/mL with ionspray, and 0.01 to 1 microgram/mL with turboionspray) yielded comparable breakdown curves. With turboionspray, a preconcentration of the aerosol occurred, yielding higher ion abundances. Solvent pH and the ratio of aqueous ammonium formate/acetonitrile had minor effects on the degree of fragmentation of haloperidol in a wide range. With these preconditions, a currently expanding mass spectral library of 400 drugs was set up by liquid chromatography/mass spectrometry with alternating orifice voltages (20, 50, and 80 V, respectively) in a looped experiment. An example of drug identification in a patient's serum with library search is shown.