LTQ 1

From Mswiki

The LTQ 1 MS is equipped with the RCADIA stage designed by our former lab technician, Aaron Bailey. Thanks to his efforts in regards to this project, Aaron published a paper in Analytical Chemistry:

Bailey AO, Miller TM, Dong MQ, Vande Velde C, Cleveland DW, Yates JR. RCADiA: simple automation platform for comparative multidimensional protein identification technology. Anal Chem. 2007 Aug 15;79(16):6410-8. PMID: 17616168

The stage consists of an eight valve rotating quaternary Surveyor MS pump thus enabling eight samples to be run (not simultaneously but rather one after another) and the option of utilizing up to four different buffers (you can use 100% of a certain buffer or apply a gradient thanks to the pump's mixing channels).

In the stage are 8 grooves designed to hold a column of standard length (16-18 cm). The columns are taped into the groove with the tip aligned properly with respect to the origin (the center of the orifice is marked as such) on the orifice of the heated capillary. So as to ensure optimal spray Aaron (Bailey) utilized a system of trial and error (moving the tip of the column around until it is an area where the best spray occurs). These positions are mapped through the use of a grid attached to the center of the stage (where X marks the proverbial "spot"). This grid is magnified via a Sony camera and it's image is output onto a small television monitor situated on top of the LTQ 1 apparatus. The grid points and their corresponding valves are as follows (from left to right):

Valve Groove Grid Position

1 1 (5,2)*

2 2 (-6,5)

3 3 (-4,10)

4 4 (-2,14)

5 5 (2,14)

6 6 (3,10)

7 7 (6,5)

8 8 (6,3)*

(For example: To get the grid position (-6,5), go down five units and then six to the left of the origin)

NOTE: I do not recommend using Grooves 1 and 8 unless you have more than 6 samples to run. The optimal spray position for these grooves is somewhat uncertain due to the fact that they seem to lack proper alignment with the orifice. These positions are not set in stone so feel free to adjust the placement of your tip as desired. Also a valve does not necessarily have to be placed into its specified groove. For example, one can place a sample from valve 3 into groove 4. Make sure to leave some space between your columns when they are placed into the grooves. This can be a good practice to employ if one of your tips forms a droplet. Spacing the tips further apart eliminates the chance of the next tip absorbing the droplet (for example if you have four samples you can run place them in grooves 1, 3, 5, and 7).

So once a sample has finished running its course, the valve will switch to the next valve containing a sample to be run thanks to an automated switching method.

Here are some pics of LTQ1 at work:

LTQ_Tune picking up spectra. The chromatography The sequence file: the methods and where the files will be stored. Check here to make sure the pressure is not too high.