Example Data Table
| Case |
Flight Time |
Path |
Voltage |
Charge |
Expected Use |
| Small organic ion |
12.5 µs |
1.0 m |
4500 V |
1+ |
Estimate m/z from detector time. |
| Peptide ion |
28.0 µs |
1.5 m |
6000 V |
2+ |
Convert m/z into neutral mass. |
| Calibration standard |
14.4 µs |
1.2 m |
5000 V |
1+ |
Build a time-square calibration. |
| Unknown analyte |
20.3 µs |
1.2 m |
Calibrated |
1+ |
Find unknown m/z from a standard. |
Formula Used
The calculator uses the kinetic energy relation for an accelerated ion.
qV = 1/2 mv²
For a flight tube of length L, velocity is:
v = L / (t - t₀)
The main mass-to-charge equation is:
m/z = 2eV(t - t₀)² / (uL²)
Predicted flight time is:
t = L × √((m/z)u / 2eV) + t₀
Required acceleration voltage is:
V = (m/z)uL² / 2e(t - t₀)²
For calibration, the calculator uses:
m/z = A(t - t₀)²,
where A = known m/z / known corrected time².
Here, e is the elementary charge.
u is the dalton in kilograms.
t₀ is the timing offset.
How to Use This Calculator
- Select the calculation mode that matches your task.
- Enter flight time, offset, path length, voltage, and charge.
- Use neutral mass only when predicting time or voltage.
- Use known m/z and known time for calibration mode.
- Press Calculate to show the result above the form.
- Use CSV or PDF buttons to save the result.
Time of Flight Mass Spectrometry Guide
What the Method Measures
Time of flight mass spectrometry separates ions by travel time.
Ions are accelerated through a known voltage.
They then move through a field-free tube.
Lighter ions usually reach the detector first.
Heavier ions travel more slowly under the same conditions.
The detector records arrival time.
That time is converted into mass-to-charge ratio.
The ratio is written as m/z.
Why Corrections Matter
Real instruments can have small timing delays.
Cable delay, detector response, and trigger timing can shift readings.
The offset value t₀ corrects that shift.
A good offset improves calibration quality.
It also improves comparisons between standards and unknown samples.
Short flight times are especially sensitive to timing errors.
Long paths and stable voltages can improve resolution.
Understanding m/z
The calculator reports m/z in daltons per charge.
A singly charged ion has mass equal to its m/z.
A doubly charged ion has neutral mass near two times m/z.
This is why charge state is important.
Wrong charge values can give wrong mass assignments.
Always confirm charge using isotope spacing or known chemistry.
Using Calibration
Calibration is useful when instrument behavior is known from standards.
A standard ion has a known m/z and measured time.
The calculator builds a time-square relation from that point.
It then estimates the m/z of an unknown ion.
This is a practical approach for teaching, quick review, and routine checks.
For final reporting, use validated instrument software and accepted calibration protocols.
FAQs
1. What does this calculator find?
It can calculate m/z, neutral mass, flight time, voltage, velocity, kinetic energy, and calibration-based unknown m/z values.
2. What is m/z?
m/z means mass-to-charge ratio. It shows ion mass divided by charge state. It is the main value reported in mass spectra.
3. Why is charge state needed?
Charge state converts m/z into neutral mass. A 2+ ion has about twice the neutral mass of its m/z value.
4. What is timing offset?
Timing offset is a correction for delays in electronics, triggering, or detection. Use zero when no correction is known.
5. Can this replace instrument software?
No. It is best for study, estimation, checking, and teaching. Use validated software for official laboratory reporting.
6. Why does higher voltage reduce time?
Higher voltage gives ions more kinetic energy. Faster ions cross the same flight path in less time.
7. What units are supported?
The form supports seconds, milliseconds, microseconds, nanoseconds, meters, centimeters, millimeters, volts, daltons, and charge state values.
8. How does calibration mode work?
It uses a known ion to build m/z = A(t - t₀)². Then it applies that relation to the unknown ion.