nanoEA sample preparation
Please consult UCSC SiL to determine optimal sample amount for your project. In general, the most important consideration is that samples are not too large for the nanoEA, rather than too small.
For the preparation of HPLC isolates for nanoEA-iRMS analysis, please refer to Broek and McCarthy (2014) for an example protocol of amino acid purification for UCSC SiL nanoEA measurement.
Samples are pelleted in tin capsules (also called tin boats). Accurate data standardization with nanoEA is dependent on accurate characterization of the blank size and isotopic composition. For consistent blank characterization between samples and standards, it is important to match tin encapsulation materials. For nanoEA, UCSC SiL uses 3.5x5 mm tin capsules purchased from Costech Analytical (100 for $13.00 part no. 41060 or 250 for $26.00 part no. 41074).
Discrete samples such as invertabrates should be weighed in individually tared capsules on an analytical microbalance precise to ±0.002 mg or better. Document individual sample weights along with sample identifier and tray and well location and share this information with UCSC SiL in a spreadsheet file.
To pellet 3.5x5 mm tin capsules, crimp the open top of the capsule closed with forceps. Fold the crimped top over once to seal in the sample and then form the capsule into a tight cube or sphere.
Pelleted samples are organized in 96-well trays (called 96-well plates by biologists). Trays need a lid designed to work with the tray. Round-bottom wells are easier to work with than flat-bottom wells. These trays are available from many suppliers. A pack of 10 trays is available for $41 from EA Consumables, SKU E2079. If you have a very small number of samples or if you do not have easy access to 96-well trays, organizing samples into labeled microcentrifuge tubes works well.
To distribute sample material into 3.5x5 mm capsules, it is sometimes helpful to stand capsules in the open diamond-shaped spaces between wells in some 96-well tray designs. These spaces have a opening that matches the diameter of the small tin capsules and prevents them from tipping. Up to 77 samples may be organized in a tray using this process.
Samples pelleted in 3.5x5 mm tin capsules have a relatively small cross section and may escape designated tray wells during shipment without additional packaging. There are two solutions to this problem. The most effective, but also more expensive, solution is to purchase silicone seals (EA Consumables SKU EA2044 or EA Consumables SKU EA2079) to cover tray wells. The less expensive solution is to cover the tray wells with several layers of aluminum foil before securing the lid. The foil forms to the shape of the wells, sealing in the pelleted samples. The matte finish side of the foil should be in contact with the samples, as the mirror finish side contains undesirable oil residues and aluminum particulates. The disadvantage of aluminum foil packaging is that an induced static charge can sometimes lift small samples out of their wells when the foil is removed.
Tape tray lids shut with four small pieces of fresh lab tape oriented perpendicular to the edge of the tray. Label the tray with another piece of lab tape oriented with well A1 on the top left. The tray label should indicate your name, a tray identifier, and a date.
Stack multiple trays, wrap in a layer of padding such as bubble wrap, and tape tightly with packing tape before packaging for shipment.
When you have a set of samples ready to ship to UCSC SiL, you will need to fill out an online sample submission form with your contact information, billing information, and basic information about the analysis.
Please ship samples to this address:
nanoEA-iRMS sample submission
When you have a set of samples ready to ship to UCSC SIL, you will need to fill out an online sample submission form with your contact information, billing information, and basic information about the analysis.