5735 GW, Aarle-Rixtel  - The Netherlands  | +31492745710 | sales@mswil.com
Blog Post

Making Meaningful nLC Connections

Making Meaningful nLC Connections

Often our customers ask us: “How do I make my connections work in my nanoLC-MS set-up?” or a variant of this phrase. In this article we will provide you with our insight into this misty territory, with many options and pitfalls.

The first question for you to answer is: “What do I want to connect and with what purpose”. Is it “just” a coupling between a transfer line and a column or emitter, or do you want to turn the connection into a Liquid Junction at the same time. In latter case, you may wish to look into some electrical safety features at the same time.

Frequently made nLC Connections

Some connections are made more than others, most nLC connections are straight through and some make use of a t-piece or cross. T’s and Crosses are used to make Liquid Junctions, using gold or platinum electrodes/wires, but T’s may also be used to facilitate vented trap-LC set-up’s. At the end of the day the fittings used are of limited specification, but whatever you combine, things do have to fit!

Here are some examples you may find being used:

VICI nLC Connections 1
VICI nLC Connections 2
VICI nLC Connections 3


Frequently used and Novel nLC Connections

Over the years a lot has stayed the same in nanoLC-land, mainly due to the resistance to change in the realms of the larger vendors. nLC connections offered today have to be stable over a 10 year plus period. Even though they say “never to change a winning team”, developments do not stop and often may improve the finicky way nLC connections are made. In making tight connections it’s all about dimensions.

1) Dimensions

Let’s start with some well used Outer Diameter (OD) dimensions:

PEEK/PEEKsil tubing:
Fused Silica tubing:
Emitters:

1/16″ of 1/32″
360-365µm (widely used) or 280µm (UltiMate™ 3000 RSLCnano System)
150µm or 360µm

2) Nuts and Bolds

Secondly, there are a number of different connectors that ensure a zero dead volume connection. Some examples are:

Making Useful nLC Connections table 1
Making Useful nLC Connections overview - Nuts and Bolds


As you can see there is a wide range of products available to make nLC connections work, however some work better than others. 10 years ago one had no choice but to use sleeves, today there are a number of options that will allow for easy leak tight connections on 360µm OD Fused Silica lines.

3) Unions

The unions and crosses themselves also come in different variants:

Making Useful nLC Connections table 2
Making Useful nLC Connections overview - Unions


Unions are made to ensure a “Zero Dead Volume” nLC connection. One note here, to add to the confusion, “zero dead volume” does not mean that there is no volume between the two ends you are connecting, it means that there is no void volume between the ends. Many ZDV-connectors have a bore in the metal divider between the lines, if the hole in the divider is similar to the inner diameter of the tubing you are connecting, then the volume in the divider is not considered “dead volume”.

The rational is that as the inner diameter of the continuous line (tube 1 – union – tube 2) is not expanded, and therefore doesn’t affect the flow, the hole is counted as part of the flow line. Dead volume, that causes your chromatography peaks to broaden, is a larger volume in which the laminar flow is disturbed. An extreme example of this are the UV-detector cells that used to be placed in-line with a Mass Spectrometer. Having said that also poorly made fittings cause dead volume and they are the main cause for dead volume in a nanoLC system, so be careful when making your own.

Any further questions or comments? Please don’t hesitate to leave them below or contact us by mail (sales@mswil.com).



One Comment

  • This is the perfect blog for everyone who would like to find out about this topic. You know a whole lot its almost hard to argue with you (not that I actually would want toÖHaHa). You definitely put a fresh spin on a subject which has been discussed for ages. Wonderful stuff, just excellent!

Leave a Reply

Your email address will not be published.

Related Posts

×

Powered by WhatsApp Chat

× How can we help?