Publications by authors named "Armin Weber"

Objectives: The study aimed to evaluate dual liquid chromatography (LC) coupled to high-resolution mass spectrometry (HRMS) for the simultaneous analysis of small and large molecule drugs by development and application of a validated bioanalytical method.

Methods: The oral antihyperglycemic drugs (OAD) dapagliflozin, empagliflozin, glibenclamide, glimepiride, metformin, pioglitazone, repaglinide, saxagliptin, sitagliptin, and vildagliptin, as well as the antihyperglycemic peptides exenatide, human insulin, insulin aspart, insulin degludec, insulin detemir, insulin glargine, insulin glulisine, insulin lispro, and semaglutide were included in the analytical procedure. Analytes were extracted using a combination of protein precipitation and solid-phase extraction.

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Recently, we presented a strategy for analysis of eight biomarkers in human urine to verify toxic mushroom or Ricinus communis ingestions. However, screening for the full panel is not always necessary. Thus, we aimed to develop a strategy to reduce analysis time and by focusing on two sets of analytes.

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Numerous case reports of intoxications with nutmeg seeds (Myristica fragrans, Houtt.) can be found in literature often following their abuse, as psychotropic effects were described after ingestions of large doses. The successful detection of the main ingredients of the nutmeg seeds essential oil elemicin, myristicin, and safrole, as well as their metabolites in human urine by gas chromatography coupled to mass spectrometry (GC-MS) was already described.

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Amatoxins are known to be one of the main causes of serious to fatal mushroom intoxication. Thorough treatment, analytical confirmation, or exclusion of amatoxin intake is crucial in the case of any suspected mushroom poisoning. Urine is often the preferred matrix due to its higher concentrations compared to other body fluids.

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The analytical proof of a toxic mushroom and/or plant ingestion at an early stage of a suspected intoxication can be crucial for fast therapeutic decision making. Therefore, comprehensive analytical procedures need to be available. This study aimed to develop a strategy for the qualitative analysis of α- and β-amanitin, psilocin, bufotenine, muscarine, muscimol, ibotenic acid, and ricinine in human urine by means of hydrophilic interaction liquid chromatography-high resolution MS/MS (HILIC-HRMS/MS).

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Paper spray mass spectrometry (PSMS) is currently used in different analytical fields, but less effort has been made so far to use PSMS for highly polar compounds. Such analytes usually show poor performance in PSMS due to their high affinity for common paper substrates in addition to high matrix effects. In this study, strategies for hydrophobic modifications of commercially available paper substrates using ten different organosilanes were developed.

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Among the emerging new psychoactive substances (NPS), compounds carrying an N-ortho-methoxybenzyl substituent, the so-called NBOMes, represented a highly potent group of new hallucinogens. Recently, 3,4-dimethoxyamphetamine (3,4-DMA)-NBOMe and 4-methylmethamphetamine (4-MMA)-NBOMe occurred, but no data on their pharmacokinetics were available. According to other NBOMes, they are expected to be extensively metabolized.

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Orbitrap technology was successfully applied for broad metabolite-based LC-high resolution (HR)-MS screening of drugs in clinical and forensic toxicology. This paper aims to elucidate whether this technology can also be used for a corresponding blood plasma screening after simple precipitation without or with consecutive on-line extraction using turbulent flow chromatography (TurboFlow). The analytes were separated within 10 min and detected by a Q-Exactive mass spectrometer in full scan mode after positive/negative switching.

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Comprehensive urine screening for drugs and metabolites by LC-HR-MS/MS using Orbitrap technology has been described with precipitation as simple workup. In order to fasten, automate, and/or simplify the workup, on-line extraction by turbulent flow chromatography and a dilute-and-shoot approach were developed and compared. After chromatographic separation within 10min, the Q-Exactive mass spectrometer was run in full scan mode with positive/negative switching and subsequent data dependent acquisition mode.

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LC-high resolution (HR)-MS well established in proteomics has become more and more important in bioanalysis of small molecules over the last few years. Its high selectivity and specificity provide best prerequisites for its use in broad screening approaches. Therefore, Orbitrap technology was tested for developing a general metabolite-based LC-HR-MS/MS screening approach for urinalysis of drugs necessary in clinical and forensic toxicology.

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Diagnosis and prognosis of poisonings should be confirmed by comprehensive screening and reliable quantification of xenobiotics, for example by gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS). The turnaround time should be short enough to have an impact on clinical decisions. In emergency toxicology, quantification using full-scan acquisition is preferable because this allows screening and quantification of expected and unexpected drugs in one run.

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TRPV6 channels function as epithelial Ca(2+) entry pathways in the epididymis, prostate, and placenta. However, the identity of the endogenous TRPV6 protein relies on predicted gene coding regions and is only known to a certain level of approximation. We show that in vivo the TRPV6 protein has an extended N terminus.

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In contrast to libraries with highly reproducible gas chromatography electron ionization mass spectra, current liquid chromatography (LC-MS) libraries are limited to specific instrument types. Therefore, the aim of the study was to prove whether a recently developed linear ion trap (LIT) LC-MS(n) screening approach and reference library can be transferred to an LC-MS/MS system with a quadrupole-LIT hybrid mass analyzer using SmileMS, a sophisticated search algorithm. The LIT reference library was built with MS² and MS³ wideband spectra recorded on a ThermoFisher LXQ LIT with electrospray ionization in positive mode and full-scan data-dependent acquisition (DDA).

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Background: To date, immunoassays are commercially available for quantification of valproic acid, salicylic acid, paracetamol, phenobarbital, phenytoin, and primidone. As they are no longer available, a fast, simple, and cost-effective quantitative gas chromatography-mass spectrometry (GC-MS) method was developed and fully validated for these drugs.

Methods: After simple and fast liquid-liquid extraction, the samples were analyzed by GC-MS using the selected ion monitoring mode.

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Today, immunoassays and several chromatographic methods are in use for drug screening in clinical and forensic toxicology and in doping control. For further proof of the authors' new metabolite-based liquid chromatography-mass spectrometry (LC-MS(n)) screening concept, the detectability of drugs of abuse and their metabolites using this screening approach was studied. As previously reported, the corresponding reference library was built up with MS(2) and MS(3) wideband spectra using a LXQ linear ion trap with electrospray ionization in the positive mode and full scan information-dependent acquisition.

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Mitragyna speciosa (Kratom in Thai), native in Southeast Asia, is increasingly misused as a herbal drug of abuse. During metabolism studies on the Kratom alkaloids mitragynine, its diastereomers speciogynine and speciociliatine as well as paynantheine in rats and humans, further isomeric compounds were detected in Kratom users' urine. The question arose whether these compounds were formed from the low abundant, isomeric alkaloids mitraciliatine (MC) and isopaynantheine (ISO-PAY).

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Methods developed for use in emergency toxicology have to be fast and simple. Additionally, such methods should be multi-analyte procedures because they allow monitoring of analytes of different drug classes in one single body sample. This is important because often only a limited amount of sample is available and the results have to be reported as fast as possible.

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Mitragyna speciosa (Kratom) is currently used as a drug of abuse. When monitoring its abuse in urine, several alkaloids and their metabolites must be considered. In former studies, mitragynine (MG), its diastereomer speciogynine (SG), and paynantheine and their metabolites could be identified in rat and human urine using LC-MS(n).

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The Thai medicinal plant Mitragyna speciosa (kratom) is misused as a herbal drug. Besides this, a new herbal blend has appeared on the drugs of abuse market, named Krypton, a mixture of O-demethyltramadol (ODT) and kratom. Therefore, urine drug screenings should include ODT and focus on the metabolites of the kratom alkaloids mitragynine (MG), paynantheine (PAY), speciogynine (SG), and speciociliatine (SC).

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In contrast to GC-MS libraries, currently available LC-MS libraries for toxicological detection contain besides parent drugs only some main metabolites limiting their applicability for urine screening. Therefore, a metabolite-based LC-MS(n) screening procedure was developed and exemplified for antidepressants. The library was built up with MS(2) and MS(3) wideband spectra using an LXQ linear ion trap with electrospray ionization in the positive mode and full-scan information-dependent acquisition.

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Mitragyna speciosa (Kratom in Thai), a Thai medical plant, is misused as herbal drug of abuse. Besides the most abundant alkaloids mitragynine (MG) and paynantheine (PAY), several other alkaloids were isolated from Kratom leaves, among them the third abundant alkaloid is speciogynine (SG), a diastereomer of MG. The aim of this present study was to identify the phase I and II metabolites of SG in rat urine after the administration of a rather high dose of the pure alkaloid and then to confirm these findings using human urine samples after Kratom use.

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The Thai medicinal plant Mitragyna speciosa (Kratom in Thai) is misused as a herbal drug of abuse. During studies on the main Kratom alkaloid mitragynine (MG) in rats and humans, several dehydro analogs could be detected in urine of Kratom users, which were not found in rat urine after administration of pure MG. Questions arose as to whether these compounds are formed from MG only by humans or whether they are metabolites formed from the second abundant Kratom alkaloid paynantheine (PAY), the dehydro analog of MG.

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A liquid chromatographic-mass spectrometric assay with atmospheric pressure chemical ionization (LC-APCI-MS) is presented for screening for, library-assisted identification (both in scan mode) and quantification (selected-ion mode) of the beta-blockers acebutolol, diacetolol, alprenolol, atenolol, betaxolol, bisoprolol, bupranolol, carazolol, carteolol, carvedilol, celiprolol, esmolol, labetalol, metoprolol, nadolol, nebivolol, oxprenolol, penbutolol, propranolol, sotalol, talinolol and timolol in blood plasma after mixed-mode (HCX) solid-phase extraction (SPE) and separation by reverse-phase liquid chromatography with gradient elution. The validation data were within the required limits. The assay was successfully applied to authentic plasma samples allowing confirmation of diagnosis of overdose situations as well as monitoring of patients' compliance.

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A liquid chromatographic/mass spectrometric assay with atmospheric pressure chemical ionization (LC/APCI-MS) is presented for fast and reliable screening and identification and also for precise and sensitive quantification in plasma of the 23 benzodiazepines alprazolam, bromazepam, brotizolam, camazepam, chlordiazepoxide, clobazam, clonazepam, diazepam, flunitrazepam, flurazepam, desalkylflurazepam, lorazepam, lormetazepam, medazepam, metaclazepam, midazolam, nitrazepam, nordazepam, oxazepam, prazepam, temazepam and tetrazepam, triazolam, their antagonist flumazenil and the benzodiazepine BZ1 (omega 1) receptor agonists zaleplone, zolpidem and zopiclone. It allows confirmation of the diagnosis of an overdose situation and monitoring of psychiatric patients' compliance. The analytes were isolated from plasma using liquid-liquid extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase.

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A liquid chromatographic/mass spectrometric assay with atmospheric pressure chemical ionization (APCI-LC/MS) is presented for the fast and reliable screening and identification and for the precise and sensitive quantification of 15 neuroleptic (antipsychotic) drugs and three of their relevant metabolites in plasma. It allows confirmation of the diagnosis of a neuroleptic overdose and monitoring of psychiatric patients' compliance. The neuroleptics amisulpride, bromperidol, clozapine, droperidol, flupenthixol, fluphenazine, haloperidol, melperone, olanzapine, perazine, pimozide, risperidone, sulpiride, zotepine and zuclopenthixol and the pharmacologically active metabolites norclozapine, clozapine N-oxide and 9-hydroxyrisperidone were extracted from plasma using solid-phase extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase.

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