Sensitive LC MS quantitative analysis of carbohydrates by Cs⁺ attachment

Abstract

The development of a sensitive assay for the quantitative analysis of carbohydrates from human plasma using LC/MS/MS is described in this paper. After sample preparation, carbohydrates were cationized by Cs ϩ after their separation by normal phase liquid chromatography on an amino based column. Cesium is capable of forming a quasi-molecular ion [M ϩ Cs] ϩ with neutral carbohydrate molecules in the positive ion mode of electrospray ionization mass spectrometry. The mass spectrometer was operated in multiple reaction monitoring mode, and transitions [M ϩ 133] ¡ 133 were monitored (M, carbohydrate molecular weight). The new method is robust, highly sensitive, rapid, and does not require postcolumn addition or derivatization. It is useful in clinical research for measurement of carbohydrate molecules by isotope dilution assay. (J Am Soc Mass Spectrom 2005, 16, 1805-1811

Multiple-reaction monitoring liquid chromatography mass spectrometry for monosaccharide compositional analysis of glycoproteins

“…Recently, several mass spectrometric studies on ionization of carbohydrates employing adduct formation between the uncharged sugar and various positive and negative ions have been reported [40 -42]. Different sugars have been quantified by LC/MRM using Na ϩ , Cs ϩ , and NH 4 ϩ in positive ESI mode [43][44][45], and I Ϫ and Cl Ϫ in negative ion mode [46 -49]. Most of these adduct formation methods used post-column addition of the ion and did not provide the required sensitivity needed for the analysis of carbohydrates that are commonly present at low abundance [40,44].…”

“…Different sugars have been quantified by LC/MRM using Na ϩ , Cs ϩ , and NH 4 ϩ in positive ESI mode [43][44][45], and I Ϫ and Cl Ϫ in negative ion mode [46 -49]. Most of these adduct formation methods used post-column addition of the ion and did not provide the required sensitivity needed for the analysis of carbohydrates that are commonly present at low abundance [40,44]. Chloride attachment by the addition of dichloromethane to a mobile phase consisting of 50% methanol provided excellent sensitivity for sorbitol with a detection limit of 5 pg, but the method still suffered from major disadvantages [49].…”

“…In addition, the method is complicated by the presence of the two chlorine isotopes, thus rendering it incompatible with the direct quantification of M ϩ2 isotopic labeled carbohydrates [47]. Cs ϩ attachment to sugars and detection in the positive LC/MRM mode showed sensitivities comparable to those of the chloride attachment method and did not suffer from the isotopic or postcolumn addition problems that are associated with the chloride adduct [44]. However, the method indirectly monitored the carbohydrate, since the MRM transitions were those of the sugar cesium adduct fragmenting to form Cs ϩ product ions.…”

Analysis of tear glucose concentration with electrospray ionization mass spectrometry

“…With gas chromatography, glucose typically needs to be derivatized to make it more volatile. Other studies used liquid chromatography to bypass the volatility issue [17,18]. Sodium [19], lithium [20,21], cesium [17], and chloride [22]°ions°have°been used with electrospray ionization to form the cationic adduct of glucose from aqueous solutions.…”

Method Optimization for Rapid Measurement of Carbohydrates in Plasma by Liquid Chromatography Tandem Mass Spectrometry

“…7,[12][13][14][15][16][17][18][19][20] ESI involves transferring compounds from liquid solution to gas phase and the formation of charged ions under a strong electrical field. This soft ionization method accomplishes a number of processes including the production of charged droplets, desolvation, ion generation, declustering.…”