Wednesday, September 8, 2010	Welcome Guest!   Register | Sign-in

Return to Knowledge Base

Knowledge Base Results

Category: LC, LC/MSD ChemStations / Data Analysis

Records returned: 5

LC, LC/MSD ChemStations / Data Analysis

1. Why are there underlines under specific letters of the selections on the Menu Bar? (id=100)

If you hold down the Alt key and press one of these underlined letters, that Main Menu Bar selection?s menu will be displayed. If you press a letter that is underlined for one of that menu?s selections, the specified function will be carried out.

2. What is a mass chromatogram? (id=101)

A mass chromatogram is a plot of the ion current of individual m/z value, a range of m/z values, or the sum of several discontinuedm/z values versus spectrum number for data acquired as a function of a chromatographic process. Some data systems, like the ChemStation, call mass chromatograms extracted ion chromatograms (EIC). There is no abbreviation or acronym for mass chromatogram. The chromatograms constructed from the sum of the ion currents of all the ions in each spectrum are sometimes called total ion chromatograms (TIC). The correct term for TIC data is reconstructed total ion current (RTIC) chromatogram. The plot of the ion current of individual m/z value, a range of m/z values, or the sum of several discontinuedm/z values versus spectrum number for data acquired through the direct infusion or the flow injection of a sample in LC/MS or the use of a direct insertion probe in GC/MS is called an extracted ion profile (EIP) or mass profile. Mass chromatograms should not be confused with selected ion monitoring (SIM) chromatograms, which result from the plot of ion currents of ions monitored during an SIM acquisition.

3. How can I annotate a chromatogram? (id=104)

You can annotate a chromatogram very easily. First, make sure that the FULL menus are selected. Do that by using the VIEW menu items. Next, under the GRAPHICS menu selection in the Data Analysis view there are annotation menu items that allow you to annotate a chromatogram. Click on "New Annotation" and when you place the mouse cursor over the chromatogram it will assume a line shape. Place the cursor where you want your annotation to be and then click the left mouse button. A dialog box will next appear. Type your text into the edit field and then press the "OK" button. You should see your annotation on your chromatogram. These same tools allow you to move and delete annotations. You can also control the font. Experiment and have fun.

4. How can I annotate a mass spectrum? (id=105)

You can annotate a mass spectrum very easily. First, use the spectrum tools to obtain the mass spectrum that you want to annotate. Next, make sure that the FULL menus are selected. Do that by using the VIEW menu items. Next, under the GRAPHICS menu selection in the Data Analysis view there are annotation menu items that allow you to annotate graphics. Click on "New Annotation" and when you place the mouse cursor over the mass spectrum it will assume a line shape. Place the cursor where you want your annotation to be and then click the left mouse button. A dialog box will next appear. Type your text into the edit field and then press the "OK" button. You should see your annotation on your mass spectra. These same tools allow you to move and delete annotations. You can also control the font. Experiment and have fun.

5. With the newest ChemStation software A.09.03 coupled to the Chemstore B.02.02, is it possible to produce overlaid chromatograms, without recalling datafiles back to ChemStation from Chemstore and thus producing an amended version? (id=116)

Chemstore was designed as a data management (review/ approval/ GLP) application. Information, charts, and other processed data can be displayed in various ways, including overlays. However, with regards to chromatographic data it assumes that the raw data processing and re- processing is/was done at the application ChemStation. This has been a long requested feature in Chemstore. To the best of our knowledge this feature is not in B.02.02 Chemstore.