in mass spectrometry, what does mass range mean in terms of detectable elements

Question

I was reading the specs of the Sample Analysis at Mars (SAM) quadrupole mass spectrometer (referred to as QMS in the paper), and I'm trying to figure out what elements it can and cannot detect. Specifically, I want to know if it can detect inorganic elements and compounds like Fe, Mn, Hg, etc. I came across these sentences about the QMS.

"Three fixed frequencies were used over the 2–535 Da mass range of QMS: 3.013 MHz for the mass range 1.5 to 19.5 Da, 1.438 MHz for the range 19.5 to 150.5 Da, and 0.853 for the range 150.5 to 535.5 Da."

Here's a link to the paper for more context. The quote is from section 6.5, 'Quadrupole Mass Spectrometer'. (https://link.springer.com/content/pdf/10.1007/s11214-012-9879-z.pdf)

What does it mean by mass range? Does that mean it can detect elements of that atomic mass because that's way heavier than any known element?

Answer 1

Quoting from linked chapter, there are two points worth addressing

A combination of radio frequency (RF) and static (DC) voltages are applied to opposite rod pairs to achieve mass separation. The voltages $\left(V_{\mathrm{dc}}+V_{\mathrm{ac}} \cos (\omega t)\right)$ and $-\left(V_{\mathrm{dc}}+V_{\mathrm{ac}} \cos (\omega t)\right)$, where $\omega$ is the frequency of $V_{\mathrm{ac}}$, result in a two-dimensional quadrupole field of the form $$ \varphi(x, y)=\left(V_{\mathrm{dc}}+V_{\mathrm{ac}} \cos (\omega t)\right)\left(x^2-y^2\right) / R_0^2 $$ where $R_0(0.5 \mathrm{~cm})$ is the distance from the $z$ (symmetry) axis to the nearest rod surface, and $x$ and $y$ are the axes crossing both the $z$ axis and nearest point of the adjacent rods. Three fixed frequencies were used over the 2-535 Da mass range of QMS: 3.013 MHz for the mass range 1.5 to 19.5 Da, 1.438 MHz for the range 19.5 to 150.5 Da , and 0.853 for the range 150.5 to 535.5 Da.

The frequencies authors refer to is the frequency ($\omega$) of the radiofrequency alternating voltage in MHz. With given frequency, ions with a range of $m/z$ will be able to pass through the quadrupole with a stable trajectory.

Now coming to your main query, what is meant by range of masses. The authors referring to a certain mass scan mode. This is explained in the next paragraph.

Mass Scan Modes: The SAM flight software is designed to allow the QMS detectors to sample during any 0.017 sec integration period (IP) any unit or fractional $\mathrm{m} / \mathrm{z}$ value within the 1.5 to 535.5 Da mass range of the instrument with a resolution of 0.1 Da. 0.003 seconds of deadtime elapse before counts are summed in a different $m / z$ value. In addition, the RF/DC rod voltages can be independently and precisely set to transmit a selected range (band) of $m / z$ values in a single IP.