TOPICS

• Apodization
• Base Level
• Baseline, correcting in FID
• Baseline, correcting in integrals
• Baseline, correcting in spectrum
• Chemical shifts, spot check
• Chemical shifts, listing
• Comment field
• Data, copying to clipboard
• Data, retrieving
• Data, saving
• DC offset, correcting
• Exponential multiplication
• FID maximum location
• Files, retrieving
• Files, saving
• Font, changing
• Fourier Transform
• Glitches, preventing
• Integrals, deleting
• Integral, listing
• Integrals, normalizing
• Integration
• Integration baseline
• Integration, limits

• Keystrokes, Mac
• Line broadening
• Macintosh keystrokes
• Peak picking
• Peak positions, spot check
• Peak positions, listing
• Phase, correcting first-order
• Phase, correcting zero-order
• Pivot point
• Plotting
• Reference, chemical shift
• Reference, integration
• Scaling, automatic
• Scale, expanding
• Scale, x, user-defined
• Scale, y, automatic
• Scale, y, user-defined
• Shifts, listing
• Shifts, referencing
• Signal-to-noise, improving
• Window functions
• Zooming

Automatic intensity (y) scaling

When a spectrum is displayed in NUTS, the intensity (y) values are automatically scaled so that the tallest peak is shown full height. You can change this with the up and down cursor keys. If you change the display and later want to reset it to its original vertical expansion, type CTRL-y.

Base Level

When you start the NUTS software, you see a nearly blank screen. This is the Base Level, as indicated at the bottom. Many of the operations you will perform invoke subroutines. When you are in a subroutine, you will see its name in place of the words "Base Level".

Baseline correction

To perform baseline correction of your spectrum, type bc.

Chemical-shift reference

To set a chemical-shift reference, left-click on the appropriate peak and type o while holding the mouse button down. Enter the desired chemical-shift value when requested.

Data retrieval

To retrieve data for analysis, select File/Open and find the file you are interested in. Make sure that you select the appropriate data type, or use Auto Detect.

DC offset removal (FID baseline correction)

To perform a DC-offset (baseline) correction to your FID, type bc. This prevents the appearance of some spurious glitches in the spectrum.

Exponential multiplication; also called apodization, line broadening, or window processing

To set the line-broadening factor (LB), select Conditions under the Process menu, and input an appropriate value for LB. Close the dialog box, and type em in the command line area. This operation is performed in order to improve the signal-to-noise ratio.

FID maximum location

To perform this correction (for Bruker digital data only), type rd. The software will read the appropriate parameters from the data file, so accept whatever values are proposed.

Font selection

To change the font (style, or size) type fv and enter selection when requested.

Fourier Transform

The Fourier Transform is effected by typing ft in the command line.

Integration

To integrate peaks, type id in the command line of the Base Level. You will see a light gray line extending across the spectrum; this is the total integral trace. The small scroll bar on the left side of the screen is used to control the magnification of the integral. Adjust it so that you can see the entire trace. To define integration limits for a particular peak, double-lick to the left of the peak, then single-click to the right. Repeat for any other peaks of interest. To delete an integral, click on the trace and type d. To set the area of one peak equal to a specific number, left-click on that peak and type v while holding the mouse button down. Enter the value you want. Type enter to return to the Base Level. The integral display can be toggled on and off with CTRL-i.

If you find that your integral baselines are not flat, enter the integral baseline correction routine from the Integral level. Type b and adjust the zero-order (slope) terms with the left mouse button, and the first-order (curvature) terms with the right. In practice, it is often easiest to make the first-order corrections before the zero-. This process may need to be repeated. Type enter to return to the Integral level; then enter again to get to the Base Level.

Macintosh Keystrokes

Commands indicated as CTRL-x really do use the CONTROL key, not the COMMAND (Apple) key. Commands shown as LEFT CLICK are a single click on a one-button mouse; those given as RIGHT CLICK are actually SHIFT-CLICK.

Output (to plotter, file, or clipboard)

Typing pl will plot the spectrum as it is shown on the screen. You can add a comment to the spectrum (sample name, your name, ID#, etc.) by typing co and inserting the desired text where indicated. You can save your data in the normal way with File/Save or File/Save As. You can copy your spectrum to the clipboard as a bitmap with CTRL-c. The spectrum can then be pasted into another application, such as a word-processing program, with CTRL-v.

Peak picking or peak listing

To view the positions of the peaks in your spectrum, type pp. Type fv to change the label font size (10 is a convenient choice). To paste a list of the peak positions onto the spectrum, type CTRL-b. This list will be included when you print the spectrum. To toggle the labels on and off, press CTRL-p.

Peak position spot check

If you want to quickly spot-check the position of a peak, hold down the left mouse button to bring up the set of crosshairs. Place the crosshairs on the peak you're interested in, and read the position in the lower right corner of the screen.

Phase correction

To do phase corrections, identify the largest peak in the spectrum. Left-click and line up the crosshairs over the selected peak. Type p while holding down the mouse button. This selects the pivot point, at which the zero-order correction will be done. To complete the phasing routine in NUTS, type ph to enter. The spectrum will look slightly different; this allows it to be redrawn faster during the phasing process. Left-click the mouse and move it right and left (for coarse adjustment) or up and down (for fine control) until the baseline on either side of the pivot peak becomes symmetric. During this process, some peaks may decrease in size or even seem to disappear; they will reappear when you return to the Base Level. Right-click the mouse and move it right and left (for coarse adjustment) or up and down (for fine control) until the baseline becomes even. Press the return key to go back to the Base Level.

Zooming, or chemical-shift (x) scale expansion

To zoom in on a region of the spectrum, type zo. You will set a small set of crosshairs. Left-click and drag to highlight the region you want to expand. Right-click to go to the highlighted region. Use the scroll bar at the bottom of the screen to move to the right and left at the expanded scale. A right-click toggles between the full and zoomed scales.To expand the data between two specified limits, type f and set the limits in point, Hz, or (most likely) ppm.