Frequency To PPM Calculator

PPM Formula:

\[ PPM = \frac{Freq\ Shift}{Ref\ Freq} \times 10^6 \]

Chemical Shift (PPM):

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1. What is PPM in NMR Spectroscopy?

PPM (parts per million) is the standard unit for reporting chemical shifts in Nuclear Magnetic Resonance (NMR) spectroscopy. It provides a field-independent measure of resonance frequency relative to a reference compound.

2. How Does the Calculator Work?

The calculator uses the PPM formula:

\[ PPM = \frac{Freq\ Shift}{Ref\ Freq} \times 10^6 \]

Where:

\( Freq\ Shift \) — Frequency shift from reference (Hz)
\( Ref\ Freq \) — Reference frequency of the spectrometer (MHz)
\( 10^6 \) — Conversion factor to parts per million

Explanation: This calculation normalizes the frequency shift to the operating frequency of the NMR spectrometer, allowing comparison of chemical shifts across different instruments.

3. Importance of PPM Calculation

Details: Accurate PPM calculation is essential for identifying chemical compounds, determining molecular structure, and comparing NMR data from different spectrometers. It eliminates instrument-dependent variations in chemical shift measurements.

4. Using the Calculator

Tips: Enter frequency shift in Hz and reference frequency in MHz. Both values must be positive numbers. The calculator will provide the chemical shift in ppm.

5. Frequently Asked Questions (FAQ)

Q1: Why use PPM instead of Hz for chemical shifts?
A: PPM is field-independent, allowing direct comparison of NMR spectra acquired on different spectrometers with different magnetic field strengths.

Q2: What is a typical reference frequency for NMR?
A: Common reference frequencies are 60, 100, 200, 300, 400, 500, or 600 MHz, depending on the spectrometer's magnetic field strength.

Q3: How do I measure frequency shift?
A: Frequency shift is the difference in Hz between your sample's resonance and the reference compound's resonance (usually TMS at 0 ppm).

Q4: What is the range of typical chemical shifts?
A: For ¹H NMR: 0-12 ppm; for ¹³C NMR: 0-220 ppm. The actual range depends on the nucleus being studied.

Q5: Can this calculator be used for different nuclei?
A: Yes, the PPM calculation formula is universal for all NMR-active nuclei, though the reference frequencies and typical shift ranges vary.