Liquid Matrix for N-Glycan Analysis by MALDI-MS
Liquid matrix maintains liquid fluidity even under vacuum conditions, forming relatively homogeneous matrix-sample droplets and achieving softer ionization.
It is prepared by mixing basic amine and acidic compound (e.g. conventional matrix CHCA).
Our laboratory has been researching and developing liquid matrices for more sensitive and softer ionization.
Fukuyama developed G3CA by mixing TMG and CA. MALDI-MS using G3CA detected sulfated-glycan and sialic acid glycan with less fragmentation and better S/N ratio than that using 2,5-DHB.
3-AQ/CHCA is not our invention, but it is a widely used liquid matrix.
Kaneshiro found that 3-AQ/CHCA derivatized 3-AQ to reductive terminus of N-glycan on MALDI sample plate. 3-AQ derivatized N-glycan was analyzed by MALDI-MS with higher sensitivity than using solid matrix 2,5-DHB.
Also Fukuyama developed 3-AQ/CA by adding mixing 3-AQ and CA instead of CHCA. The 3-AQ/CA showed the same 3-AQ derivatization to N-glycan but softer ionization than that using 3-AQ/CHCA.
2,5-DHB: 2,5-dihydroxybenzoic acid, G3CA: 1,1,3,3-tetramethylguanidinium (TMG,G) salt of p-coumaric acid (CA), 3-AQ/CHCA: 3-aminoquinoline/α-cyano-4-hydroxycinnamic acid, 3-AQ/CA: 3-aminoquinoline/ p-coumaric acid.
 Fukuyama Y, Nakaya S, Yamazaki Y, Tanaka K : Ionic liquid matrixes optimized for MALDI-MS of sulfated/sialylated/neutral oligosaccharides and glycopeptides. Anal Chem 80:2171–2179. 2008. https://doi.org/10.1021/ac7021986
 Kaneshiro K, Fukuyama Y, Iwamoto S, Sekiya S, Tanaka K : Highly sensitive MALDI analyses of glycans by a new aminoquinolinelabeling method using 3‐aminoquinoline/α‐cyano‐4‐hydroxycinnamic acid liquid matrix. Anal Chem 83: 3663–3667. 2011. https://doi.org/10.1021/ac103203v
 Fukuyama Y, Funakoshi N, Takeyama K, Hioki Y, Nishikaze T, Kaneshiro K, Kawabata S, Iwamoto S, Tanaka K: 3-Aminoquinoline/p-Coumaric Acid as a MALDI Matrix for Glycopeptides, Carbohydrates, and Phosphopeptides. Anal Chem 86: 1937-1942. 2014. https://doi.org/10.1021/ac4037087
Note: This column was originally published on LinkedIn in October 2020. Affiliations and titles are as of that time.
Shinichi Iwamoto, PhD
Deputy General Manager, Koichi Tanaka Mass Spectrometry Research Laboratory
Shinichi Iwamoto joined Shimadzu Corporation in 1991. As a research and development team for biometrics, he developed near-infrared brain function measurement devices and applied research. He was a founding member of the Koichi Tanaka Mass Spectrometry Research Laboratory, established in 2003. Since then, he has been involved in developing elemental technology and applied research of MALDI-MS. He became Deputy General Manager in 2014. He has been engaged in designing fundamental technologies for new mass spectrometers, methods for microbial analysis, and disease biomarkers for cancer and Alzheimer's disease.