A rapid and accurate quantitative method was developed and validated for the analysis of four urinary organic acids with nitrogen containing functional groups, formiminoglutamic acid (FIGLU), pyroglutamic acid (PYRGLU), 5-hydroxyindoleacetic acid (5-HIAA), and 2-methylhippuric acid (2-METHIP) by liquid chromatography tandem mass spectrometry (LC/MS/MS). The chromatography was developed using a weak anion-exchange amino column that provided mixed-mode retention of the analytes. The elution gradient relied on changes in mobile phase pH over a concave gradient, without the use of counter-ions or concentrated salt buffers. A simple sample preparation was used, only requiring the dilution of urine prior to instrumental analysis. The method was validated based on linearity (r2 ¡Ý 0.995), accuracy (85¨C115%), precision (C.V. < 12%), sample preparation stability (¡Ü 5%, 72h), and established patient ranges. The method was found to be both efficient and accurate for the analysis of urinary zwitterionic organic acids.

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Introduction Oligonucleotides are short nucleic acid chains, usually 19-27mer long. They bind to their corresponding chain, making a specific inhibition possible. In pharmaceuticals, this can be used to inhibit the expression of a gene or protein of interest. Oligonucleotides are usually analyzed based on separation using both hydrophobic and ion-exchange properties. In this project, the possibility to use a mixed-mode column to separate these oligonucleotides and their impurities were explored. Method Liquid chromatography is used as the separation method and the method of detection is both mass spectrometry and UV. Three different columns are evaluated; C18, DNAPac RP, and mixed-mode RP/WAX. Results and discussion Different compositions of mobile phases and gradients are evaluated based on a literature study. Triethylamine, triethylammonium acetate, ammonium formate, hexafluoroisopropanol is used along with both methanol and acetonitrile. Phosphate buffer is evaluated on LC-UV. The results from the C18 column displays a good separation of the oligonucleotides, whilst the DNAPac RP is not as sufficient using the same mobile phases. The mixed-mode column provides good separation and selectivity using phosphate buffer and UV detection. Conclusion Mixed-mode column has the potential to be used for separation of oligonucleotides and one future focus would be to make the mobile phase compatible with mass spectrometry. Phosphate buffer and UV detection seems to be the go-to mobile phase using mixed-mode column even though MS is a more powerful tool for the characterization and identification of oligonucleotides. This provides a hint about the challenge in making the mobile phase MS compatible.

Per- and polyfluorinated substances (PFAS) are compounds that consist of a carbon chainbackbone that is partially or entirely fluorinated, with an addition of a functional group. SomePFAS are known as persistent organic pollutants (POPs) and have therefore been drawing a lot ofattention as well as increased concerns. PFAS have been detected in humans, wildlife and theenvironment and some have exhibited toxic effects such as hepatotoxicity, immunotoxicity,reproductive toxicity and endocrine disruption as well as being persistent and bioaccumulative.Serum, plasma and whole blood have been used as biomonitoring matrices in many studies toevaluate human exposure to PFAS. Restrictions have been applied to some PFAS, but thesecompounds are still ubiquitous. This study will investigate the performance (recovery, matrixeffect (ME) in terms of intra-/inter-day repeatability) of ion-pair extraction (IPE) and solid phaseextraction with weak anion exchange (SPE-WAX). The extraction methods were adapted fromliterature and 13 PFAS were selected for this work based on prior biomonitoring studies. Thetarget PFAS content was analyzed with liquid chromatography coupled with tandem massspectrometry (LC-MS/MS). The extraction methods were also compared for extractableorganofluorine (EOF) extraction in terms of blank levels as well as the amount extracted withdifferent methods; the EOF content was measured with combustion ion chromatography (CIC).The EOF levels were used to estimate the amount of unidentified organofluorine (UOF), to avoidunderestimating potential health hazards. Samples extracted using IPE had an average ionizationenhancement of 9%, while SPE-WAX showed an average ionization suppression of -1%. SPEWAXshowed higher average recoveries for procedural blanks (78%), horse serum (96%) andhuman serum (95%) in comparison to IPE (69%, 36%, 88%, respectively). The CIC analysis forEOF content was observed to be below MDL (&lt;50 ng/mL F) with some contaminations observedin the procedural blanks.