The use of ammonia as reagent gas increases considerably the utility of chemical ionization mass spectroscopic (ci-ms) analysis: compounds of biological interest, such as steroid hormones, bile acids, prostaglandins, phospholipids, alkaloids, antibiotics, etc., display strong pseudomolecular ions (mostly M+ + 18). The need for derivatization and/or chromatographic purification of many types of compounds is sharply reduced. Ammonium carbonate or 15NH4Cl can be introduced into the direct probe for obtaining satisfactory ci-ms(NH3) spectra. Bile salts and some bile acid conjugates can be studied without derivatization. Potassium penicillanate gives a strong peak corresponding to the free acid + NH4+. Deproteinized blood samples provide a detailed picture of individual components, such as triglycerides, lysolecithins, cholesterol esters, etc. Frag-mentation patterns for structural information can be generated by adding argon to ammonia. One shortcoming of the ci-ms(NH3) method is the progressive replacement of halogen with hydrogen.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology