title: Desalting by crystallization: detection of attomole biomolecules in picoliter buffers by mass spectrometry.
abstract: Sensitive detection of biomolecules in small-volume samples by mass spectrometry is, in many cases, challenging because of the use of buffers to maintain the biological activities of proteins and cells. Here, we report a highly effective desalting method for picoliter samples. It was based on the spontaneous separation of biomolecules from salts during crystallization of the salts. After desalting, the biomolecules were deposited in the tip of the quartz pipet because of the evaporation of the solvent. Subsequent detection of the separated biomolecules was achieved using solvent assisted electric field induced desorption/ionization (SAEFIDI) coupled with mass spectrometry. It allowed for direct desorption/ionization of the biomolecules in situ from the tip of the pipet. The organic component in the assistant solvent inhibited the desorption/ionization of salts, thus assured successful detection of biomolecules. Proteins and peptides down to 50 amol were successfully detected using our method even if there were 3 × 10(5) folds more amount of salts in the sample. The concentration and ion species of the salts had little influence on the detection results.
authors: Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Department of Chemistry, Tsinghua University , Beijing 100084, China.|National Institute of Metrology , Beijing 100013, China.
authors: Xiaoyun
authors: X
authors: Gong
authors: National Institute of Metrology , Beijing 100013, China.
authors: Xingchuang
authors: X
authors: Xiong
authors: Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Department of Chemistry, Tsinghua University , Beijing 100084, China.
authors: Song
authors: S
authors: Wang
authors: Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Department of Chemistry, Tsinghua University , Beijing 100084, China.
authors: Yanyan
authors: Y
authors: Li
authors: Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Department of Chemistry, Tsinghua University , Beijing 100084, China.
authors: Sichun
authors: S
authors: Zhang
authors: National Institute of Metrology , Beijing 100013, China.
authors: Xiang
authors: X
authors: Fang
authors: Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Department of Chemistry, Tsinghua University , Beijing 100084, China.
authors: Xinrong
authors: X
authors: Zhang
mesh_terms: D002021:Buffers; D003460:Crystallization / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D010455:Peptides / Q000032:analysis*; D011506:Proteins / Q000032:analysis*; D012492:Salts / Q000302:isolation & purification*; D018401:Sample Size; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation / Q000379:methods*
chemical_list: D002021:Buffers; D010455:Peptides; D011506:Proteins; D012492:Salts