How to Use

1. Start with Introduction and Help

Open Introduction to see what the tool does and how it saves time at the bench. One can always use the Help menu for quick access to this guide (How to use), Tips & Tricks, Community and News & Updates.

2. Open the Medium Calculator

Click Go to Medium Calculator or the Medium Calculator button in the top bar. You will see three modules.

• Module 1 — Stock Preparation: prepare 100× Inorganic Salts, 100× Salts & Vitamins, 10× Amino Acids, or Additional Components.
• Module 2 — Assemble DMEM: choose Standard DMEM or DMEM Variations.
• Module 3 — Individual Compounds and Custom Media: prepare single compounds & other media formulations.

3. Stock Preparation for DMEM

1. Click Stock Preparation and pick one tab:
   • 100× Inorganic Salts: magnesium sulfate and sodium dihydrogen phosphate dihydrate pre-stocks combined to 100×.
   • 100× Salts & Vitamins: combination of vitamins and trace salts.
   • 10× Amino Acids: amino acids.
   • Additional Components: prepare single stocks (weigh in) and ready-to-use (store-bought in solution) additional compounds.
2. Type the Volume (mL) you want to prepare. Tables and instructions update immediately for master stocks. Mass and adjusted volume fields update as you type. If the weight you actually measured differs, enter it in Actual weight measured (mg). The Adjusted Volume shows how much solvent to add for the exact molarity.
3. In case you change the stock volume, the component list updates and the component volume (V) is now suggested in the calculators below so you can weigh straight away.
4. Use Print All Data in each tab to get a checklist for the bench.

4. Assemble complete medium with Standard DMEM

1. Click Standard DMEM.
2. Enter the Prepared volume in mL. Every section scales automatically.
3. Work through the color coded sections in order:
   • Initial additions water, 25× sodium chloride, 25× sodium bicarbonate.
   • Inorganic Salts master stock 100× stock volume.
   • Salts & Vitamins master stock 100× stock volume.
   • Additional Components folic acid, riboflavin, D-glucose.
   • Amino Acids master stock 10× stock volume.
   Water is backfilled automatically so the total reaches your prepared volume.
4. Fill the pH Adjustment table. Target pH is 8.1 to 8.2 for standard DMEM. Record pH before, the µL of HCl you added, and pH after.
5. Check post-pH additional components (single stocks weighed in and store-bought in solution). Add these just before use.
6. Use Reset All to clear the page or Print to take a bench sheet.

5. Customize with DMEM Variations

Choose one of two workflows inside DMEM Variations.

• Applications preconfigured recipes for Seahorse, NAM-free, Met-free, Trp-free, Trp tracing, and SILAC Nascent.
  1. Select the application from the buttons at the top. For SILAC, pick the treatment inside the sub-menu.
  2. Enter the final volume. Tables scale automatically.
  3. Adjust pH. Seahorse media target pH 7.4. All other applications target pH 8.1 to 8.2.
  4. Add the post-pH additional components just before use. Use Print Final Assembly when you are ready.
• Ingredients Based toggle specific groups on or off.
  1. Pick a Variant from the dropdown. Use Modify All to see every group at once or choose Modify Salts & Vitamins, Modify Amino Acids, or Modify Inorganic Salts.
  2. Enter the prepared volume.
  3. Tick the checkboxes for the items you want to include. The water needed and the completion message update live.
  4. Adjust pH, review the post-pH additional components, then Print Final Assembly.

Tip: If you remove a nutrient for an experiment, prepare a control medium using the same workflow and volume where that nutrient is present.

6. Build fully custom media in Individual Compounds and Custom Media

1. Open Individual Compounds and Custom Media.
2. For each row enter the compound name, molar mass in g per mol, desired concentration in mol per liter, and the volume in mL.
3. Mass and mg update automatically as you type. If your balance shows a different value, enter it in Actual weight measured and the Adjusted Volume updates automatically.
4. Use Add Another Compound to insert more rows, up to thirty.
5. Use Print All Data to generate a single checklist.

7. Printing and resets

• Every module has a Print or Print Final Assembly button that opens a clean layout. You can save it as PDF or print it.
• Use Reset All where available to clear that page. Use Reset All Calculators in Stock Preparation to clear the calculators across tabs.
• The Back button returns you to where you came from without clearing your inputs.

Using the Back button (not the browser back)

The app has its own “← Back” button at the top-left of most pages.

• What it does: Jumps to the previous screen inside the app and preserves everything you’ve entered—no reloads or resets.
• Where to find it: Look for “← Back” at the top of each section (e.g., Stock Preparation, Standard DMEM, Variations).
• Shortcut: Press Esc to trigger the in-app Back button.

Note: If accidentally the page reloads, we have added an auto-remember automatic option from your last location for 8 hours in the same tab.

Tips & Tricks

Here are some practical, helpful considerations on how to streamline your media preparations:

• Label Everything: When making master stocks or final media, note the date, concentration, and any pH adjustments. This avoids confusion later on.
• Warm Water Helps: For compounds that dissolve slowly (like potassium chloride), gently warm the solvent to speed up dissolution—but don't overheat sensitive reagents.
• Protect Light-Sensitive Stocks: Cover riboflavin or folic acid solutions with foil and store in the dark to prevent degradation.
• Use Dialyzed FBS for Starvation: When omitting small molecules (e.g., amino acids or vitamins) it's best to use dialyzed FBS to avoid residual nutrients sneaking in.
• Keep Aliquots Handy: Store master stocks in aliquots (5–50 mL) at -20 °C or -80 °C so you can thaw only what you need and maintain consistency.
• Check pH Early: After mixing base components, adjust to 8.1–8.2 before sterile filtration. A small pH shift can dramatically affect cell growth.
• Print and Tally: Print out your tick-off list or calculation summary and check off items as you measure. It ensures you don't skip a step when busy at the bench.
• Validate with a Small Batch: If trying a new formulation, prepare a 50 mL test batch first to confirm solubility and pH behavior before scaling up.
• Keep a Logbook: Record any deviations—like slight volume tweaks due to measuring inaccuracies—so you can troubleshoot if cells behave unexpectedly.

Help

Find guides and tips below:

• How to Use: Detailed guide on using the calculator.
• Tips & Tricks: Common media composition shortcuts and storage information.

Medium Calculator

Select one of the options below:

Stock Preparation

Select which stock to prepare:

Standard DMEM (Final Assembly)

DMEM Variations

DMEM Variations – Ingredients Based

DMEM Variations – Applications

Contact & Citation

We're here to help! If you have any questions or feedback, please reach out to:

• Division of Metabolic Crosstalk in Cancer
  German Cancer Research Center (DKFZ), Heidelberg
  Francisco Yanqui-Rivera:

  mediaminds@dkfz.de

Please cite our tool as:
Seifert, Yanqui-Rivera, et al. (2025). A step-by-step guide to performing cancer metabolism research using custom-made media. Life Science Alliance, 9(2), e202503529. doi: 10.26508/lsa.202503529

Read the full article here.