any reliable LC instrument on prep application

[jiang295]

I want to use it for up to 40mm column with particle size 5micron, right now I have one system from shimadzu LH-8a. I am not happy with this system. pressure fluctuation a lot when I increase pressure to 300bar.
any instrument that can handle up to 400bar and can produce very reliable gradient elution.
thanks a lot if you can recommend one.
o

[Bruce Hamilton]

Have you asked Shimadzu to assess the system and check that it performs to specification?.

The cause of the pressure pulses should be investigated, as most prep systems from reputable manufacturers are expensive because they offer support. It may simply be a faulty check value or pulse dampener.

If do want a different prep system, you can look at the models offered by reputable manufacturers such as Water, Agilent, Dionex, etc. I have an Agilent 1100 system that works well for me. The main issue is to ensure that local suport is good, and that you don't buy an orphan ( the only one in the serviceperson's territory ).

[elsico]

Agreed with Bruce, but depends on your budget you can find something economy and not so famous. Shimadzu 8 is old system but if it is serviced well must work correct. First way clean check valves and maybe put dynamic mixer before injection valve.

[jiang295]

thanks for both of response.
how big dynamic mixer you would put before injection valve if I run at 15ml/min?
any reason doing that?

Agreed with Bruce, but depends on your budget you can find something economy and not so famous. Shimadzu 8 is old system but if it is serviced well must work correct. First way clean check valves and maybe put dynamic mixer before injection valve.