Andersen Cascade Impactor Calculator

Calculator Inputs

Reference flow rate

Actual flow rate

Fine particle limit µm

Blank correction per location

Assay correction percent

Label claim or target dose

Decimal places

Stage Mass Entries

Device retention mass

Induction port / throat mass

Preseparator mass

Stage 0 mass (9 µm nominal)

Stage 1 mass (5.8 µm nominal)

Stage 2 mass (4.7 µm nominal)

Stage 3 mass (3.3 µm nominal)

Stage 4 mass (2.1 µm nominal)

Stage 5 mass (1.1 µm nominal)

Stage 6 mass (0.7 µm nominal)

Stage 7 mass (0.4 µm nominal)

Final filter mass

Formula Used

Flow corrected cutoff: corrected cutoff = nominal cutoff × square root(reference flow ÷ actual flow).

Corrected mass: corrected mass = maximum of zero and ((raw mass − blank correction) × assay correction factor).

Total recovered dose: sum of corrected masses from device, throat, preseparator, stages, and filter.

Emitted dose: total recovered dose − device retention.

Cumulative undersize percent: mass on lower stages and filter ÷ sized stage mass × 100.

Fine particle dose: interpolated undersize percent at the selected limit × sized stage mass.

MMAD and GSD: calculated with log-probit regression where valid cumulative points are available. Log interpolation is used as fallback.

How to Use This Calculator

Enter the reference flow and the measured operating flow.
Enter the fine particle cutoff used by your method.
Add blank correction and assay correction values when needed.
Enter the recovered mass for each impactor location.
Use one mass unit throughout the complete form.
Press Calculate to show results below the header.
Use CSV or PDF buttons to download the report.

Example Data Table

Location	Example mass	Nominal cutoff µm	Meaning
Device retention	38.4	N/A	Mass left in the device
Induction port / throat	62.8	N/A	Large upper deposit
Preseparator	45.2	N/A	Coarse aerosol collection
Stage 0	31.7	9.0	Largest sized stage deposit
Stage 1	42.1	5.8	Upper respirable boundary
Stage 2	54.9	4.7	Fine particle transition
Stage 3	61.5	3.3	Middle fine fraction
Stage 4	49.6	2.1	Lower fine fraction
Stage 5	28.3	1.1	Small particle stage
Stage 6	15.4	0.7	Very small particles
Stage 7	8.2	0.4	Submicron boundary stage
Final filter	5.6	N/A	Smallest collected mass

Andersen Cascade Impactor Calculation Guide

Why This Calculator Matters

An Andersen cascade impactor separates an aerosol into size based fractions. Each stage captures particles above its effective cut point. The remaining particles pass to lower stages or the final filter. Analysts then convert recovered masses into performance values. These values help compare formulations, devices, batches, and operating conditions. This calculator keeps those steps organized. It also documents assumptions, corrections, and downloadable records.

Core Measurements

The main inputs are deposited mass values for the induction port, preseparator, stages, and filter. Blank correction removes background mass. Assay correction adjusts for recovery or potency. Flow correction changes stage cutoffs when actual flow differs from the reference flow. Higher flow normally shifts the effective cut point downward. Lower flow shifts it upward. The tool applies that adjustment before calculating cumulative undersize percentages.

Interpreting Results

Total recovered dose shows the complete measured mass. Emitted dose excludes device retention when that value is entered. Fine particle dose estimates the mass below the selected fine particle limit. A common limit is five micrometers, but some methods use another value. Fine particle fraction can be reviewed against recovered dose and emitted dose. MMAD shows the diameter where half of the sized aerosol mass is smaller. GSD describes spread. A narrow GSD means the aerosol sizes are grouped closely. A wider GSD means the distribution is more varied.

Good Data Practice

Use the same mass unit for every entry. Do not mix micrograms and milligrams in one run. Confirm the flow rate and the reference flow before reporting results. Review unusually high throat or preseparator deposits. They may show device, handling, or dispersion issues. Check mass balance against label claim when claim data is available. Large differences may indicate sampling loss, extraction error, or calculation setup problems.

Reporting Tips

Keep the stage table with every result. It provides traceability for audits and method reviews. Download the CSV file for spreadsheets. Download the PDF file for a simple lab summary. Repeat the calculation after each correction change. Compare batches using the same settings. Consistent settings make trends easier to defend. The calculator supports fast review, but method validation remains essential. Always follow your approved procedure and equipment instructions during review.

FAQs

What does this calculator estimate?

It estimates recovered dose, emitted dose, fine particle dose, fine particle fraction, MMAD, GSD, and cumulative undersize values from impactor stage mass data.

Which mass unit should I use?

Use one consistent unit for all entries. The result will use that same unit. Do not mix micrograms, milligrams, or assay response units.

Why is flow correction included?

Stage cutoffs change when operating flow changes. The calculator adjusts nominal cutoffs using a square root flow relationship for practical review.

What is MMAD?

MMAD is the aerodynamic diameter where fifty percent of the sized aerosol mass is smaller and fifty percent is larger.

What is GSD?

GSD describes the spread of a lognormal particle size distribution. Larger values show a wider aerosol size range.

What does fine particle dose mean?

It is the estimated mass below the selected fine particle limit, often five micrometers, based on cumulative undersize interpolation.

Why is my MMAD missing?

MMAD may be missing when stage masses are zero or when the cumulative distribution does not cross fifty percent.

Can this replace a validated method?

No. It supports calculation and review. Always follow the approved laboratory method, equipment instructions, and quality requirements.