we have a 20 microliter volume loop, but i want to use more volume loop because of more injection volume
Hi,
Usually, injection loops are provided with the LC system, and if that is not the case for you, you can get in touch with the vendor.
Please note that you should also consider the volume of the syringe that is in the autosampler you're using, as that can still be limiting the amount of volume that can be injected.
Simply purchase one from a supplier. Anyone who relies on a manual injector (vs an autoinjector) should have several different fixed volume loops available to them for use.
- Note: You can not use any volume you like. The volume used must be appropriate for and suitable for use with your HPLC system, injection valve and of course the HPLC method. Choosing a volume that is too large will degrade the chromatography and/or invalidate the method used. Please get help from a local professional before making any changes. Additionally, make sure you are familiar with how to properly swage HPLC fittings and work on the system too.
- "HPLC Tubing and Fittings; An introduction to Nuts, Ferrules and Tubing Choices"; https://hplctips.blogspot.com/2018/07/hplc-tubing-and-fittings-introduction.html
To make your own HPLC valve injection loop, use water and an analytical balance for better accuracy. Obtain an appropriate length and diameter of HPLC grade capillary tubing (316 Stainless Steel or PEEK, if applicable) from a reputable source. Determine the approximate length needed for the desired volume (refer to TABLE below in link). Cut the tubing to size. Weigh and tare it. Fill the tubing with water and record the mass (use a syringe and fingertight fitting). 1 ul of water has a mass of 1 mg at STP conditions. Adjust the length of the tubing to match the desired volume.
- "HPLC Capillary Tubing Connection Volumes:"; https://hplctips.blogspot.com/2012/10/capillary-tubing-connection-volumes.html
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