NUCLEODUR® silica with 1.8 µm particle size
Miniaturization in HPLC has a long history. It started in the early stage of HPLC development with the reduction of particle size from 10 µm via 7 μm to standard 5 µm – which is still the most widely used particle diameter in analytical HPLC – to 3 µm spherical particles which so far was the smallest particle size available for gaining higher theoretical plates and efficiencies.
With the introduction of the 1.8 µm NUCLEODUR® particles researchers have turned over an exciting leaf in HPLC column technology.
Features of 1.8 µm NUCLEODUR® particles
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Increase of separation efficiency by higher number of theoretical plates (N):
50 x 4.6 mm NUCLEODUR® C18 Gravity
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3 µm:
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N ≥ 100 000 plates/m (h value ≤ 10)
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1.8 µm:
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N ≥ 166 667 plates/m (h value ≤ 6)
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Increase of the plate number by ~ 67 % offers the possibility of using shorter columns with equal plate numbers resulting in a decrease of analysis time.
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Significant improvement in resolution
Use of 1.8 μm instead of 3 µm particles leads to an increase of resolution by a factor 1.29 (29 %)
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Higher flow rates and shorter run times
Optimal flow rate for 1.8 µm particles is higher than for 3 and 5 µm particles – the flow rate should be at the van-Deemter minimum.
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Van-Deemter plot
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Column back pressure
Due to the smaller particle size the back pressure will increase.
Because of the high sphericity of the NUCLEODUR® particles and the very narrow particle size distribution we are able to keep the back pressure on a moderate level.
Thus NUCLEODUR® columns can be used on modernen ultra fast HPLC instruments as well as in combination with conventional HPLC systems with pumps up to 400 bar.
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Comparison of back pressures
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Eluent:
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100 % methanol |
Flow rate:
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1.5 ml/min |
Temperature:
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22 °C |
Column dimensions:
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50 x 4.6 mm
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NUCLEODUR® C18 Gravity
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Competitor
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3 µm
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70 bar
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1.8 µm
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130 bar
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170 bar
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Technical requirements
To gain the best result in ultra fast HPLC based on 1.8 μm particles certain technical demands on the instrument are made.
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pumps for pressures of 250 – 1000 bar
flow rates of 2 – 3 ml
minimized dead volumes of the LC system
fast data recording
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Versatile selectivities
All NUCLEODUR® premium phases are available with 1.8 µm particles.
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C18 Gravity
C8 Gravity
C18 Isis
C18 Pyramid
Sphinx RP
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