Dipeptides in CSF and plasma: diagnostic and therapeutic potential in neurological diseases.

Dipeptides (DPs), composed of two amino acids (AAs), hold significant therapeutic potential but remain underexplored. Given the crucial role of AAs in central nervous system (CNS) function, this study investigated the presence of DPs in cerebrospinal fluid (CSF) and their correlation with corresponding AAs, potentially indicating their role as AA donors. Plasma and CSF samples were collected from 43 children with neurological or metabolic conditions of unknown origin, including 23 with epilepsy.

Validated UPLC-MS/MS method for the analysis of vitamin B pyridoxal 5́-phosphate, pyridoxal, pyridoxine, pyridoxamine, and pyridoxic acid in human cerebrospinal fluid.

Vitamin B and its metabolites play a crucial role in the development and interaction of brain metabolism. Following diagnostic improvements additional inherited disorders in vitamin B metabolism have been identified, most of them leading to a severe epileptic disorder accompanied by progressive neurological deficits including intellectual disability and microcephaly. Since early treatment can improve the outcome, fast and reliable detection of metabolic biomarkers is important.

Development and validation of a hydrophilic interaction liquid chromatography-tandem mass spectrometry method for the quantification of the antidiabetic drug metformin and six others pharmaceuticals in wastewater.

A rapid and sensitive hydrophilic interaction liquid chromatography (HILIC)-tandem mass spectrometry method was developed and fully validated for the simultaneous determination of the antidiabetic drug metformin and six further pharmaceuticals (atenolol, gabapentin, levofloxacin, ciprofloxacin, propranolol and trimethoprim) in influent and effluent wastewater. Five deuterated related compounds were used as internal standards in order to control the extraction, injection and ionization variability. Two solid phase extraction methods and Oasis HLB 1cc cartridge, using only 1mL sample with acid or basic pH-value were optimized and compared in order to match the specificity of both influent and effluent wastewater matrixes.

Post-column infusion of internal standard quantification for liquid chromatography-electrospray ionization-tandem mass spectrometry analysis - Pharmaceuticals in urine as example approach.

Liquid chromatography with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) technique is gaining more and more attraction as the method of choice for multi-sample analysis. However, it is strongly susceptible to the influence of matrix components. Matrix effects are the main source of substantial losses in detection sensitivity and have to be compensated via complex quantification methods In this work, we introduce a sophisticated quantification method for the LC-ESI-MS/MS analysis of 16 substances in urine samples using a single continuously post-column infused internal standard (PCI-IS) for matrix effect correction.

Evaluation of the matrix effect of different sample matrices for 33 pharmaceuticals by post-column infusion.

Matrix effects that occur during quantitative measurement by liquid chromatography mass spectrometry specifically when using electrospray ionization are a widely recognized phenomenon. Sample matrix compounds affect the ionization process of the target analytes, lead to a low signal response, and flawed analytical results. How these matrix compounds directly influence the ionization process has not yet been completely understood.

Development of a SPE-HPLC-MS/MS method for the determination of most prescribed pharmaceuticals and related metabolites in urban sewage samples.

Based on regional prescription data several pharmaceuticals with variable amounts of prescription and corresponding metabolites were selected and analyzed in influent and effluent samples of the sewage treatment plant (STP) in Dresden, Germany. Pharmaceuticals of the following most prescribed therapeutic groups were chosen: antibiotics, antifungals, anticonvulsants, antipsychotics, antidepressants, and cardiovascular active compounds like beta blockers and angiotensin-converting enzyme inhibitors. To analyze the selected compounds, a multi-target method was developed and applied to 24-h composite wastewater samples for three single days in May and June 2014.

Simultaneous determination of most prescribed antibiotics in multiple urban wastewater by SPE-LC-MS/MS.

A rapid analytical method was developed for the application of a long-term monitoring (>one year) of the most prescribed and often in hospitals used antibiotics in diverse wastewaters of an urban sewage treatment plant (STP). Additionally to the selected multi-class antibiotics amoxicillin, penicillin V and piperacillin (penicillins), cefotaxime and cefuroxime (cephalosporins), azithromycin, clarithromycin and roxithromycin (macrolids), ciprofloxacin and levofloxacin-ofloxacin (fluoroquinolones), clindamycin (lincosamide), doxycycline (tetracycline), sulfamethoxazole (sulfonamide) and trimethoprim (dihydrofolate reductase inhibitor), the bioactive metabolite clindamycin-sulfoxide, the reserve antibiotic vancomycin (glycopeptide) and as tracer of the STP the anticonvulsant carbamazepine and the antifungal fluconazole were involved. The analytical method combines a low-sample-volume solid phase extraction (SPE), followed by a chromatographic separation using a reversed phase (RP) and hydrophilic interaction liquid chromatography (HILIC) technique, respectively, coupled to a triple quadrupole mass spectrometer.