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  • P-ISSN2233-4203
  • E-ISSN2093-8950

Vol.10 No.4

Hyoung Jun Lee(Korea Research Instiute of Standards and Science (KRISS)) ; Yong-Hyeon Yim(Korea Research Instiute of Standards and Science (KRISS)) pp.103-107 https://doi.org/10.5478/MSL.2019.10.4.103
초록보기
Abstract

Low-temperature plasma (LTP) ionization is one of the ambient ionization methods typically used in mass spectrom- etry (MS) for fast screening of chemicals with minimal or no sample preparation. In spite of various advantages of LTP ioniza- tion method, including simple instrumentation and in-situ analysis, more general applications of the method are limited due to poor desorption of analytes with low volatilities and low ionization efficiencies in the negative ion mode. In order to overcome these limitations, an ultrasonic vibrator of a commercial hand-held humidifier was interfaced with an LTP ionization source, which generated microdroplets from sample solutions and assisted with LTP ionization. Ionization behaviors of various chemi- cals in microdroplet-assisted LTP (MA LTP) were tested and compared with typical LTP ionization from dried samples applied on a surface. MA LTP efficiently ionized small organic, amino, and fatty acids with low volatilities and high polarities, which were hardly ionized using the standard LTP method. Facile interaction of LTP with ultrafine droplets generated by ultrasonic res- onator allows efficient ionization of relatively non-volatile and polar analytes both in the positive and negative ion modes.

Marta Kołek(Mickiewicz University) ; Rafał Frański(Mickiewicz University) ; Magdalena Frańska(Poznań University of Technology) pp.108-111 https://doi.org/10.5478/MSL.2019.10.4.108
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Abstract

The hydrolysis of penicillin G, carbenicillin and ampicillin in pure water at room temperature was studied by high pressure liquid chromatography electrospray ionization mass spectrometry. Hydrolysis of ampicillin did not occur under these conditions; however, penicillin G and carbenicillin were completely hydrolyzed after seven days. A short interpretation of this difference is proposed. The mass spectrometric behaviour, namely ESI response and fragmentation pathway, of hydrolyzed pen- icillin G and hydrolyzed carbenicillin have been also discussed.

Sang Tak Lee(Sogang University) ; Jae-ung Lee(Sogang University) ; Joo-Hyon Kim(National Institute of Environmental Research) ; Han Bin Oh(Sogang University) pp.112-116 https://doi.org/10.5478/MSL.2019.10.4.112
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Abstract

In this study, a chloroform consumer chemical product (CCP) reference material (RM) is successfully developed, with potential to be used in the proficiency testing of hazardous compounds in CCPs for analysis and testing agencies. Validation experiments are rigorously conducted to evaluate whether the RM meets the requirements set by the ISO 13528 and ISO Guide 35, using a reliable GC/MS method for the analysis of chloroform. The obtained calibration plot linearity, limit of detection (LOD), and limit of quantitation (LOQ) are excellent. The developed RM meets the homogeneity and stability requirements; the between-unit (s bb ) and within-unit (s wb ) standard deviations are less than 2.5%, and the stability is found to be guaranteed for 50 days.

Seonghyun Yu(Sogang University) ; Hwa-yong Jang(Sogang University) ; Han Bin Oh(Sogang University) pp.117-122 https://doi.org/10.5478/MSL.2019.10.4.117
초록보기
Abstract

This study demonstrated the sensitivity of electron capture dissociation mass spectrometry (ECD-MS) to probe sub- tle conformational changes in gaseous melittin ions induced by the substitution of an amino acid. ECD-MS was performed for triply and quadruply-protonated melittin and its variants obtained by a single amino acid substitution, namely, D-Pro14, Pro14Ala, and Leu13Ala. Although native triply-protonted melittin showed only a few peptide backbone cleavage products, the D-Pro14 and Pro14Ala variants exhibited extensive backbone fragments, suggesting the occurrence of a significant structural or conformational change induced by a single amino acid substitution at Pro14. On the contrary, the substitution at Leu13, namely Leu13Ala (+3), did not cause significant changes in the ECD backbone fragmentation pattern. Thus, the sensitivity of ECD-MS is demonstrated to be good enough to probe the aforementioned conformational change in melittin.

Mass Spectrometry Letters