I agree with Don that you should confirm with the manufacturer. I also concur that the "1" is a multiplier. The reason has to do with the various ways of measuring noise.
In most cases, when a signal/noise spec is defined, it's based on "peak to peak" noise (which is just what is sounds like: the difference between the maximum and minimum excursions of the baseline). Peak to peak noise (PtP) is easy to measure manually on a printout (absent the nit-picky issues of how long a stretch of signal to use and, on a chromatogram, where to measure), but is extraordinarily complicated for a data system.
"Root mean square" noise (RMS) is the square root of the sum of the squares of the deviations from the average baseline. As such is it easy for a data system to computer.
The catch is that the relationship between RMS and PtP noise depends on the waveform. I've seen values from 2.8 to 3.3 for sine waves (i.e., PtP = 3.3 x RMS) to 8 for white noise (e.g.,
http://mdc.custhelp.com/app/answers/det ... peak-noise).
What that "1x" is telling you is simply that the spec is based on RMS, not any version of PtP.