In order to increase sensitivity and ability to handle increasingly smaller samples from biological sources we developed a nano-electrospray source. The source is made of an xyz-translation stage and a specially machined holder for pulled silica tubes spray needles. The source can be operated in two modes, stand alone mode were a few mL of sample are placed into a large diameter spray needle and with the assistance of air pressure can be sprayed at a very low rate (10-25 nL/min). A very small sample can be investigated for a prolong time and multiple MS and product ion MS spectra can be measured. In cases were the samples needs to be separated or concentrated using nano-LC, a smaller spray needle is connected to a 50-100 mm diameter HPLC column. The second objective of this project is to develop methods for sample cleanup, sample enrichment and sample injection onto a capillary column with minimal sample loss. We have started developing an HPLC technique using a 10 port injection micro valve, incorporating a large sample loop and a sample cleaning and enrichment mini column (0.3x15 mm). Another aspect under development is gradient generation at the low flows needed (80-100 nL/min). We have chosen to use a special mHPLC pump (MicroTech) capable of producing gradients at 10 mL/min and further reduce the flow by a custom built 1:100 splitter.
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