🧪 MolarPrep | Host Cell Lab Suite

Fast, reliable molarity and stock-solution calculations for laboratory workflows.

Repo • Live App

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What is MolarPrep?

MolarPrep is a lightweight web app for preparing solutions with fewer calculation mistakes, especially in repetitive or high-pressure lab work.

It helps you calculate:

1. How much solid reagent to weigh to prepare a target molar solution
2. How much concentrated liquid stock to pipette (using density and purity)

The app is designed to reduce common errors such as:

• decimal point shifts
• unit conversion mistakes
• confusion between mM / µM / nM
• stock concentration estimation from reagent density + purity

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How it works

MolarPrep currently includes two calculation modules.

1) Solid reagents (mass to weigh)

Use this when you have a dry reagent and want to prepare a solution with a target molarity.

Formula used:

$$ m(g) = M\left(\frac{mol}{L}\right) \times V(L) \times MW\left(\frac{g}{mol}\right) $$

Where:

• m = required mass in grams
• M = target molarity
• V = final volume
• MW = molecular weight

✅ Supports target molarity units:

• M
• mM
• µM
• nM

✅ Supports final volume units:

• L
• mL

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2) Liquid reagents (concentrated stock volume)

Use this when your reagent is a liquid stock (for example acids/solvents/reagents sold by density and purity) and you need to prepare a target molar solution.

Step A: Estimate stock molarity from density and purity

$$ M_1 = \frac{P \times \rho \times 1000}{MW} $$

Where:

• P = purity fraction (e.g., 98% → 0.98)
• ρ = density in g/mL
• MW = molecular weight in g/mol

Step B: Use dilution equation

$$ V_1 = \frac{M_2 \times V_2}{M_1} $$

Where:

• M₁ = stock molarity
• V₁ = volume of stock required
• M₂ = target molarity
• V₂ = target final volume

✅ Output is automatically displayed in practical units (L / mL / µL depending on scale)

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Smart output and error handling

MolarPrep includes a simple validation layer to reduce bad inputs:

• Non-positive values return ERR
• Invalid or missing inputs return ERR
• Small outputs are automatically shown with a better metric prefix:
  • g → mg → µg
  • L → mL → µL

This is intentionally simple and explicit so users can catch mistakes quickly.

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Installation / PWA (optional)

MolarPrep can be installed as a Progressive Web App (PWA) on supported browsers.

Desktop / Android

• Open the live app
• Click the Install button (if shown), or use browser install prompt

iPhone / iPad (Safari)

• Open the live app
• Tap Share
• Select Add to Home Screen

Once installed, it can work offline after the necessary files are cached.

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👨‍🔬 Author

Emiliano Balderas Biotechnology Engineer | PhD Student in Biochemistry Instituto de Biotecnología (IBt) - UNAM.

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Part of the Host Cell Suite

MolarPrep is part of Host Cell, a suite of practical tools for bioprocessing and lab workflows.