Light stabilizers are additives that are widely used to improve the lifespan and performance of polymer materials. To develop advanced polymer materials, analytical techniques investigate the degradation mechanisms and distribution of additives in polymers are crucial. Herein, two extraction–ionization methods were used: tapping-mode scanning probe electrospray ionization (t-SPESI) and liquid extraction surface analysis (LESA). The distribution and molecular structure of the photodegradation products were investigated using polyethylene films containing two types of oligomeric hindered amine light stabilizers (o-HALS). In addition, to study the relationship between light irradiation time and the relative amount of photodegradation products, we developed a method for preparing films with multiple photodegradation regions. Mass spectrometry imaging (MSI) using t-SPESI (t-SPESI-MSI) revealed that the signal intensities of HALS decreased with the time of light irradiation, and its degradation products progressively changed. Moreover, tandem mass spectrometry (MS/MS) using LESA (LESA-MS/MS) revealed that degradation products were generated by HALS fragmentation in the polymer film. By integrating these results, we propose multiple and stepwise reactions for the formation of the photodegradation products. Results indicate that the combined use of t-SPESI-MSI and LESA-MS/MS can directly analyze and understand the photodegradation mechanism of o-HALS in polymer materials.

We report a robotic sheath-flow probe electrospray ionization mass spectrometry system with a new probe design and automated positioning capabilities for pinpoint ambient mass spectrometry. The system integrates a 3-axis Cartesian robot with two cameras: a fixed global camera for coarse positioning and a movable local camera for fine alignment, enabling users to designate sampling spots by mouse-clicking on live images displayed on the graphical user interface. A microcontroller is used for voltage control, current monitoring, and the detection of probe–sample contact. Sampling, transfer, ionization, and cleaning are fully automated under computer control, and the sheath liquid is supplied by a programmable syringe pump to maintain a stable flow rate. The system successfully analyzed aqueous standards, beverages, and water-rich soft materials such as jelly and fruit slices, yielding stable ion signals with negligible carry-over between measurements.

Congenital disorders of glycosylation (CDG) constitute a group of rare inherited metabolic disorders resulting from mutations in genes involved in the biosynthesis of glycan chains that are covalently attached to proteins or lipids. To date, nearly 200 genes have been identified as responsible for these disorders, with approximately half implicated in N-glycosylation defects. Diagnosis of CDG is primarily achieved through genetic analysis and the identification of glycan abnormalities, referred to as molecular phenotypes. With the increasing use of whole exome and genome sequencing in the investigation of diseases with unknown etiology, the number of cases suspected of CDG is increasing, highlighting the necessity for glycan analysis. Molecular phenotyping in CDG typically targets glycoproteins, with transferrin and apolipoprotein CIII being key representatives of N- and mucin-type O-glycosylation, respectively. Mass spectrometry (MS) provides rapid analysis and yields moderately detailed information, establishing it as a first-line molecular diagnostic tool that complements genetic analysis. Structural anomalies detected by MS can be classified into distinct patterns, which may indicate specific defects within the glycosylation pathway. In cases of CDG types that lack clear molecular phenotypes, characteristic metabolites can often be identified and quantified by MS, further aiding in the diagnostic process. Molecular diagnosis of CDG using MS can be performed with a standard mass spectrometer and a dried blood spot on filter paper, enabling its application in population-based mass screening.

Electrospray ionization mass spectrometry of neat undiluted ionic liquid (IL) and the analysis of protein with the doping of IL were performed using high-pressure electrospray. The use of disposable micropipette tips as emitters eased the handling of viscous and easy-to-clog samples and improved the reproducibility of the measurement. A high-pressure operation enabled the stable electrospray of the highly conductive IL from these relatively large bore emitters. The measurement of the current–voltage relationship of 1-ethyl-3-methylimidazolium tetrafluoroborate (Emim BF₄) revealed an unusual negative differential resistance that has not been seen in the typical atmospheric or high-pressure electrospray. Mass spectrometric analysis of this IL also showed the characteristic response of various ion species with the emitter voltage. When added to the commonly used protein solution, the mass spectrum also showed protein peaks that correspond to the adduction of fluoroboric acid molecules (HBF₄).

Mass spectrometry (MS) is a valuable tool that enables label-free analysis and the ability to measure multiple molecules. The atmospheric pressure MS imaging (MSI) method usually requires tedious sample preparation. A simple ionization method with minimal sample preparation is needed for high-throughput analysis. We have developed an ion source that does not require sample preparation such as thinning, curing, planarization, or addition of matrix by the electrospray-assisted laser desorption/ionization with gas transportation (ELDI-GT). The sample is transported with nitrogen gas through a heated tube to the electrospray. The ion signal of protonated caffeine was measured under different transport conditions. The ion signal intensity was found to increase 11-fold by changing the flow rate and tube temperature from 2.8 cm³/s and 473 K to 25 cm³/s and 673 K. ELDI-GT was able to visualize the localization of caffeine crystals at a pixel size of 50 µm using MSI because of the effective GT using the heated tube. The dependence of the ion signal intensity was discussed on the amount of heat applied to the sample in the heated tube. ELDI-GT allowed accurate localization of caffeine at a pixel size of 50 µm without the need to apply thinning and matrix to a sample.