title: Quantitative analysis of polyhexamethylene guanidine (PHMG) oligomers via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with an ionic-liquid matrix.
abstract: BACKGROUND
  Quantifying polymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) with a conventional crystalline matrix generally suffers from poor sample-to-sample or shot-to-shot reproducibility. An ionic-liquid matrix has been demonstrated to mitigate these reproducibility issues by providing a homogeneous sample surface, which is useful for quantifying polymers. In the present study, we evaluated the use of an ionic liquid matrix, i.e., 1-methylimidazolium α-cyano-4-hydroxycinnamate (1-MeIm-CHCA), to quantify polyhexamethylene guanidine (PHMG) samples that impose a critical health hazard when inhaled in the form of droplets.
  
  
  METHODS
  MALDI-TOF mass spectra were acquired for PHMG oligomers using a variety of ionic-liquid matrices including 1-MeIm-CHCA. Calibration curves were constructed by plotting the sum of the PHMG oligomer peak areas versus PHMG sample concentration with a variety of peptide internal standards.
  
  
  RESULTS
  Compared with the conventional crystalline matrix, the 1-MeIm-CHCA ionic-liquid matrix had much better reproducibility (lower standard deviations). Furthermore, by using an internal peptide standard, good linear calibration plots could be obtained over a range of PMHG concentrations of at least 4 orders of magnitude.
  
  
  CONCLUSIONS
  This study successfully demonstrated that PHMG samples can be quantitatively characterized by MALDI-TOFMS with an ionic-liquid matrix and an internal standard.
authors: Department of Chemistry, Sogang University, Seoul, 121-742, Korea.
authors: Donhee
authors: D
authors: Yoon
authors: Dongkun
authors: D
authors: Lee
authors: Jong-Hyeon
authors: JH
authors: Lee
authors: Sangwon
authors: S
authors: Cha
authors: Han Bin
authors: HB
authors: Oh
mesh_terms: D002934:Cinnamates / Q000737:chemistry; D006146:Guanidines / Q000032:analysis* / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D016014:Linear Models; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: C518937:1-methylimidazolium alpha-cyano-4-hydroxycinnamate; D002934:Cinnamates; D006146:Guanidines; D007093:Imidazoles; D052578:Ionic Liquids; C060540:polyhexamethyleneguanidine