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MRA Mass Rate Attenuator

MRA adjustable flowsplitter for preparative range

Reduction of the solvent flow to the amount
required for MS or other detectors

A high-frequency rotor directs the sample to the detector and optimises its performance.The flow distribution
in the MRA is independent of the viscosity of the mobile phase (gradient curve), of temperature variations and
capillary length.

Performance characteristics

Freely selectable split ratio from 100:1 to 100.000:1 for optimum operation of your HPLC/MS or HPLC/NMR system.

Rapid adjustment of the split-ratio at the touch of a button.

  • Dead volume reduced to a minimum
    The low system volume minimizes band broadening and delay times.
  • Precise, uniform split ratio
    Since the split ratio is determined by the valve rotation, it is independent of the viscosity of the mobile phase, tube length, pressure or temperatures.
  • Automated mode
    During separation the split ratio can be easily changed manually or via the system control.

Function principle

The adjustable flowsplitter uses a rapid-switch rotor to direct the sample from one flow stream to another. The sensor recognizes two positions: aliquot fill and aliquot transfer.

In the aliquot transfer position the flow is directed through port 3 into the MRA via an auxiliary pump and the aliquot already in the chamber is fed into the analytical flow of a detector via port 4.


Split ratios:

100:1 to 100.000:1

Switching frequency:

20.0 Hz to 2.0 Hz

Nominal size of the aliquot:

22 nl, 100 nl, 300 nl

Nominal pressure:

6,9 Mpa (69 bar, 1000 psi)

Surfaces moistened:

stainless steel, RPC-8 (polymer)


automated mode via short-circuit control or RS-232

Dimensions (h x w x d):

approx. 14 x 8 x 19 cm


Managing Director:
Joachim Paschlau

HRB 135721 München
WEEE-Reg.Nr. DE 66898529


Gesellschaft für den Vertrieb wissenschaftlicher Geräte
Otto-Hahn-Strasse 28-30
85521 Riemerling
Tel: +49 89 66055696
Fax: +49 89 60824826