How to prepare leucine enkephalin solution for a Waters Q-Tof? - WKB2368

OBJECTIVE or GOAL

Leucine enkephalin is supplied as a powder in a 3-mg vial. The following procedure guides you in making up various concentrations of leucine enkephalin.

ENVIRONMENT

• This is a standard that is used on all of Waters Q-Tofs.

PROCEDURE

Leucine enkephalin

• C₂₈H₃₇N₅O₇
• Tyr Gly Gly Phe Leu
• Masslynx: (M+H) m/z 556.2771, (M-H) m/z 554.2615
• UNIFI: (M+H)+ m/z 556.2766, (M-H)- m/z 554.2620

2 ng/μL leucine enkephalin

1. Using a 5-mL pipette, add 7.5 mL of water to the contents of a 3-mg (±0.15 mg) bottle of leucine enkephalin.
2. Recap, shake well, and sonicate for five minutes.
3. Label as "400 ng/μL leucine enkephalin in water" and store in a freezer (expires in three months).
4. Using a 200-μL pipette, transfer 100 μL of the 400 ng/μL leucine enkephalin in water to a 20-mL volumetric flask.
5. Make up to 20 mL with 50:50 acetonitrile/water + 0.1% formic acid and sonicate for five minutes.
6. Label as "2 ng/μL leucine enkephalin in 50:50 acetonitrile/water + 0.1% formic acid" and store in a freezer (expires in one month).
7. For fluidics systems, transfer from the 20-mL volumetric flask to a 30-mL fluidics container and label as "2 ng/μL leucine enkephalin in 50:50 acetonitrile/water + 0.1% formic acid" and store in a freezer (expires in one month).

1 ng/μL leucine enkephalin

1. Using a 5-mL pipette, add 7.5 mL of water to the contents of a 3-mg bottle of leucine enkephalin.
2. Recap, shake well, and sonicate for five minutes.
3. Label as "400 ng/μL leucine enkephalin in water" and store in a freezer (expires in three months).
4. Using a 200-μL pipette, transfer 50 μL of the 400 ng/μL leucine enkephalin in water to a 20-mL volumetric flask.
5. Make up to 20 mL with 50:50 acetonitrile/water + 0.1% formic acid and sonicate for five minutes.
6. Transfer from the 20-mL volumetric flask to a 30-mL fluidics container.
7. Label as "1 ng/μL leucine enkephalin in 50:50 acetonitrile/water + 0.1% formic acid" and store in a freezer (expires in one month).

200 pg/μL leucine enkephalin

1. Decant approximtely 4 mL of the 2 ng/μL leucine enkephalin in 50:50 acetonitrile/water + 0.1% formic acid solution into a 5-mL glass vial.
2. Using a 1,000-μL pipette, transfer 2,000 μL of the 2 ng/μL leucine enkephalin in 50:50 acetonitrile/water + 0.1% formic acid solution to a 20-mL volumetric flask.
3. Make up to 20 mL with 50:50 acetonitrile/water + 0.1% formic acid and sonicate for five minutes.
4. Label as "200 pg/μL leucine enkephalin in 50:50 acetonitrile/water + 0.1% formic acid" and store in a refrigerator (expires in two weeks).
5. For fluidics systems, transfer from the 20-mL volumetric flask to a 30-mL fluidics container and label as "200 pg/μL leucine enkephalin in 50:50 acetonitrile/water + 0.1% formic acid" and store in a refrigerator (expires in two weeks).

50 pg/μL leucine enkephalin

1. Using a 1,000 μL pipette, transfer 500 μL of the 2 ng/μL leucine enkephalin in 50:50 acetonitrile/water + 0.1% formic acid solution to a 20-mL volumetric flask.
2. Make up to 20 mL with 50:50 acetonitrile/water + 0.1% formic acid and sonicate for five minutes.
3. Label as "50 pg/μL leucine enkephalin in 50:50 acetonitrile/water + 0.1% formic acid" and store in a refrigerator (expires in one week).

ADDITIONAL INFORMATION

Leucine enkephalin comes in many kits. On the Waters Web site, search for leucine enkephalin, or you can follow this link.