Trypan Blue exclusion is one of the most widely used methods for estimating cell viability in research laboratories. It offers a simple way to distinguish cells with intact plasma membranes from cells that have lost membrane integrity.
The method is commonly used before cell seeding, passaging, cryopreservation, transfection, cytotoxicity studies, and other downstream experiments. It can provide two essential pieces of information: the percentage of viable cells in a sample and the concentration of viable cells per milliliter.
The principle is straightforward. Viable cells exclude the dye and remain bright or unstained, while cells with compromised membranes absorb Trypan Blue and appear blue under a microscope.
Despite its simplicity, the method requires a consistent workflow. Mixing technique, staining time, cell clumping, sample homogeneity, chamber loading, and microscope focus can all affect the final result. In particular, the time between mixing the cells with the dye and performing the count should be carefully controlled.
This practical guide explains how the Trypan Blue exclusion assay works, how to perform a reliable cell count, how to calculate viability, and how to avoid the most common sources of error.
What Is Trypan Blue?
Trypan Blue is a membrane-impermeant dye used to evaluate cell viability through the dye exclusion principle.
Under normal assay conditions, the dye does not readily cross the intact plasma membrane of a viable cell. Cells with an intact membrane therefore remain clear, bright, or unstained.
When membrane integrity is lost, Trypan Blue can enter the cell and bind to intracellular components. These cells develop a distinctive blue appearance and are classified as non-viable or membrane-compromised.
The assay generally separates cells into two groups:
- Viable cells: bright or unstained cells that exclude Trypan Blue.
- Non-viable cells: blue-stained cells with compromised membrane integrity.
The total cell count includes both populations.
Trypan Blue therefore provides a rapid estimate of membrane-integrity-based viability. It does not directly measure metabolic activity, mitochondrial function, ATP production, proliferative capacity, or the specific biological mechanism responsible for cell death.
This distinction is important when interpreting results. A cell that excludes Trypan Blue has an intact membrane at the time of measurement, but this does not necessarily mean that the cell is fully functional or capable of long-term proliferation.
How the Trypan Blue Exclusion Principle Works
The plasma membrane acts as a selective barrier between the intracellular and extracellular environments.
In viable cells, the membrane prevents Trypan Blue from entering during the short assay period. These cells remain unstained and can usually be identified by their bright or translucent appearance.
When cells become severely damaged or die, membrane permeability increases. Trypan Blue then enters the cell, producing the characteristic blue staining observed under bright-field microscopy.
The assay is therefore based on dye uptake rather than on an active enzymatic or metabolic reaction.
This makes the method fast and easy to interpret. However, it also means that Trypan Blue cannot reliably detect every form or stage of cellular stress. Early apoptotic cells, for example, may retain an intact membrane and exclude the dye even though the apoptotic process has already begun.
How Viable and Non-Viable Cells Appear
Under a bright-field microscope:
- Viable cells normally appear bright, clear, or lightly refractile.
- Non-viable cells appear blue.
- Cellular debris may appear dark, irregular, or smaller than intact cells.
- Aggregates may contain a mixture of stained and unstained cells.
The analyst should define clear criteria for distinguishing intact cells from debris and fragments. Borderline objects should be classified consistently across samples.
Focus and illumination also matter. Poor focus can change the apparent brightness or boundary of a cell. This may lead to viable cells being classified as stained or cellular fragments being counted as non-viable cells.
For consistent results, use the same microscope configuration, magnification, focus procedure, and counting rules throughout the experiment.
What Is Trypan Blue Used For?
Trypan Blue is frequently used for routine cell counting and viability assessment in research laboratories.
The assay is particularly useful when researchers need a rapid estimate of cell concentration before starting another experimental procedure.
Common applications include:
- Routine maintenance of cell cultures.
- Adjustment of cell seeding density.
- Assessment of cultures before passaging.
- Evaluation of cells after thawing.
- Preparation of cells for transfection.
- Normalization of samples before functional assays.
- Monitoring cell viability following experimental treatments.
- Preparation of cells for cryopreservation.
- Preliminary assessment of cytotoxic effects.
Because Trypan Blue provides both a viability percentage and a viable cell concentration, it offers more useful information than a total cell count alone.
Two samples may contain the same total number of cells but very different numbers of viable cells. For example, a suspension with 2 × 10^6 total cells/mL and 95% viability contains many more viable cells than a suspension with the same total concentration and 60% viability.
This difference can have a significant effect on downstream experiments.
Routine Cell Culture and Seeding
Cell density affects many aspects of cell culture performance.
Seeding too few cells may delay growth, reduce cell-to-cell interactions, or produce weak assay signals. Seeding too many cells may cause premature confluence, nutrient depletion, altered metabolism, or changes in gene expression.
Trypan Blue counting helps researchers adjust cultures according to the concentration of viable cells rather than the total number of visible particles.
A typical workflow may involve:
- Harvesting or detaching the cells.
- Resuspending the cells into a homogeneous suspension.
- Mixing an aliquot with Trypan Blue.
- Counting viable and stained cells.
- Calculating viable cell concentration.
- Diluting the suspension to the required seeding density.
This approach improves comparability between experiments, particularly when the starting viability differs between cell passages or treatment groups.
Assessment After Cell Thawing
Cryopreservation and thawing can damage cells.
A Trypan Blue count shortly after thawing can provide an initial estimate of membrane integrity and help determine whether the recovered culture contains enough viable cells to continue.
However, viability immediately after thawing may not fully predict subsequent attachment or growth. Some cells may exclude the dye initially but fail to recover or proliferate.
For this reason, Trypan Blue results may be complemented with observations of attachment, morphology, growth rate, or a functional viability assay when long-term recovery is important.
Preparation for Downstream Assays
Many experiments require a defined number of viable input cells.
Examples include:
- Cell proliferation assays.
- Cytotoxicity assays.
- Reporter gene assays.
- Transfection experiments.
- Flow cytometry.
- Immunological assays.
- Colony formation assays.
- Cell-based screening.
- Gene expression studies.
Using the total cell concentration instead of the viable cell concentration may introduce substantial variation.
For example, when a protocol requires 20,000 viable cells per well, researchers should calculate the required volume using the number of unstained cells rather than the total number of cells.
Researchers who need additional functional information can explore the Canvax Cell Based Assays range.
How to Perform a Trypan Blue Exclusion Assay
The following workflow provides a practical starting point for manual counting with a 0.4% Trypan Blue solution.
The exact sample volume and counting procedure may vary depending on the hemocytometer, counting chamber, cell type, and internal laboratory method.
Materials Required
A standard manual Trypan Blue workflow normally requires:
- A homogeneous cell suspension.
- Trypan Blue Solution, 0.4%.
- Calibrated micropipettes.
- Suitable pipette tips.
- A clean hemocytometer and coverslip.
- A bright-field or inverted microscope.
- A timer.
- Appropriate laboratory protective equipment.
Before staining, inspect the cell suspension.
The sample should contain a well-dispersed population of cells with as few aggregates as possible. Large cell clumps can lead to undercounting because several cells may be recorded as a single object.
Cells also settle quickly. Mix the original suspension immediately before removing the aliquot used for counting.
Recommended Mixing Ratio
A commonly used protocol combines:
1 part 0.4% Trypan Blue solution with 1 part cell suspension
Examples include:
- 10 µL Trypan Blue and 10 µL cell suspension.
- 20 µL Trypan Blue and 20 µL cell suspension.
- 100 µL Trypan Blue and 100 µL cell suspension.
Maintaining a 1:1 ratio produces a dilution factor of 2.
This dilution factor must be included when calculating the concentration of cells in the original sample.
When the cell suspension has already been diluted before adding Trypan Blue, both dilution steps must be included in the calculation.
Step-by-Step Trypan Blue Protocol
1. Prepare the cell suspension
Resuspend the cells carefully to obtain a homogeneous single-cell suspension.
Avoid excessive agitation, particularly when working with fragile cells. The objective is to disperse the cells evenly without creating unnecessary mechanical stress.
2. Remove a representative aliquot
Take the counting aliquot shortly after resuspension.
Avoid leaving the tube standing for an extended period, as cells may settle and create concentration differences between the upper and lower parts of the suspension.
3. Add Trypan Blue
Mix equal volumes of 0.4% Trypan Blue solution and cell suspension unless an established laboratory method specifies a different ratio.
4. Mix gently
Mix the suspension and dye carefully by pipetting.
Avoid vigorous vortexing. Excessive mixing can generate air bubbles, affect fragile cells, and make the counting chamber more difficult to load correctly.
Gentle but thorough mixing helps distribute the dye and cells evenly.
5. Start the timer
Begin timing as soon as the cells and Trypan Blue are mixed.
The exposure time should be treated as a controlled experimental parameter.
6. Load the counting chamber
Introduce the required volume into the hemocytometer chamber.
The sample should enter the chamber evenly by capillary action. Avoid overfilling, underfilling, or introducing bubbles.
Do not use a chamber that shows an irregular distribution of liquid or cells.
7. Examine the sample promptly
Place the hemocytometer under the microscope and focus on the appropriate counting grid.
Viable cells should appear bright or unstained. Non-viable cells should appear blue.
8. Count viable and stained cells separately
Record the number of unstained and blue cells in the selected counting areas.
Use the same counting pattern and boundary rules for every sample.
A common boundary rule is to include cells touching the upper and left borders while excluding cells touching the lower and right borders. The specific rule matters less than applying it consistently.
9. Repeat the count when necessary
Count several grid areas to obtain a more representative average.
Duplicate chamber loading can help identify variability caused by poor mixing, chamber loading, or sampling.
10. Calculate viability and concentration
Calculate the percentage viability and viable cell concentration using the appropriate dilution and chamber conversion factors.
Why the 1–3 Minute Reading Window Matters
Trypan Blue staining is time-sensitive.
The cell count should begin shortly after mixing the suspension with the dye. As a practical working procedure, the sample should ideally be examined within approximately 1 to 3 minutes.
Use freshly prepared stained samples for the most reliable results.
The reading interval should remain consistent between samples. One sample should not be counted immediately while another remains exposed to Trypan Blue for a much longer period.
Prolonged exposure can damage viable cells or increase dye uptake. Cells that initially excluded Trypan Blue may gradually become stained and be incorrectly classified as non-viable.
This can produce a falsely low viability result.
For this reason, avoid preparing all stained samples at the beginning of a long counting session.
A more controlled approach is:
- Prepare one stained sample.
- Start the timer.
- Load the chamber.
- Count the sample.
- Record the result.
- Prepare the next sample.
This sequential workflow helps maintain a comparable exposure time across samples.
The 1–3 minute interval should be considered a practical recommendation rather than a universal requirement for every cell type. Fragile cells, unusual cell lines, and validated automated methods may require specific conditions.
The selected procedure should remain consistent throughout the study.
How to Calculate Cell Viability
Cell viability is calculated from the number of unstained cells and the total number of cells counted.
The standard formula is:
Cell viability (%) = Number of viable cells ÷ Total number of cells × 100
The total number of cells includes both viable and blue-stained cells.
Therefore:
Total cells = Viable cells + Non-viable cells
Cell Viability Example
Imagine that a researcher counts:
- 82 unstained cells.
- 18 blue-stained cells.
The total cell count is:
82 + 18 = 100 cells
The percentage viability is:
82 ÷ 100 × 100 = 82% viability
This means that 82% of the counted cells excluded Trypan Blue during the measurement period.
How to Calculate Cell Concentration
For a standard Neubauer hemocytometer, one large square has a volume of 10^-4 mL.
The cell concentration can therefore be calculated using:
Cells/mL = Average cells per large square × dilution factor × 10^4
When equal volumes of cell suspension and Trypan Blue are mixed, the dilution factor is 2.
Viable Cell Concentration Example
Suppose the average number of viable cells counted per large square is 82.
The sample was mixed 1:1 with Trypan Blue.
The viable cell concentration is:
82 × 2 × 10^4 = 1.64 × 10^6 viable cells/mL
If the average total count is 100 cells per square:
100 × 2 × 10^4 = 2.00 × 10^6 total cells/mL
The sample therefore contains:
- 1.64 × 10^6 viable cells/mL
- 2.00 × 10^6 total cells/mL
- 82% viability
Always verify that the formula matches the counting chamber and grid area being used. Different chambers may require different conversion factors.
Including Additional Dilutions
When the original sample has been diluted before adding Trypan Blue, the dilution factors must be multiplied.
For example:
- Initial dilution: 1:5.
- Trypan Blue dilution: 1:2.
The combined dilution factor is:
5 × 2 = 10
The final calculation would therefore use a dilution factor of 10.
Accurate dilution records are essential. A correct cell count can still produce an incorrect concentration if the dilution factor is omitted or applied twice.
Common Trypan Blue Counting Errors
Trypan Blue counting is simple, but small procedural differences can create large variations.
The most common problems involve timing, sample preparation, chamber loading, classification, and calculation.
Waiting Too Long Before Counting
Leaving cells in contact with Trypan Blue for too long can lower the apparent viability.
Initially viable cells may become damaged or gradually absorb the dye. These cells may then be counted as non-viable.
To reduce this risk:
- Prepare stained samples immediately before use.
- Begin counting within approximately 1–3 minutes.
- Use the same timing for all samples.
- Do not leave stained suspensions standing during a long counting session.
Incomplete Mixing
Poor mixing can create uneven cell and dye distribution.
One part of the sample may contain more cells than another. The aliquot loaded into the chamber may therefore fail to represent the original suspension.
Mix the cell suspension before sampling and mix the cells gently after adding the dye.
Avoid aggressive mixing that generates bubbles or damages fragile cells.
Cell Sedimentation
Cells may settle rapidly, especially in concentrated suspensions.
A sample taken from the upper part of an unmixed tube may contain fewer cells than a sample taken from the bottom.
Resuspend immediately before removing each aliquot.
When several replicate counts are performed, remix the original suspension between samples.
Cell Clumping
Cell aggregates make it difficult to identify individual cells.
A cluster may be counted as one object even when it contains several cells. Alternatively, the analyst may estimate the number of cells in the cluster, increasing subjectivity.
Improve cell dispersion before counting. For adherent cultures, review the detachment procedure when large aggregates occur frequently.
Avoid excessive mechanical treatment, as aggressive dissociation may damage cells and reduce viability.
Debris and Cellular Fragments
Debris can absorb dye or appear dark under the microscope.
Small fragments may be misclassified as dead cells, particularly after cytotoxic treatments or harsh cell handling.
Define minimum size and morphology criteria before counting.
When the sample contains substantial debris, consider complementing the manual count with another analytical method.
Air Bubbles
Air bubbles interfere with chamber filling and cell distribution.
They can displace cells, create empty areas, or make the grid difficult to evaluate.
Mix and load the chamber carefully. Discard and reload the sample when bubbles appear in the counting area.
Incorrect Chamber Loading
Overfilling or underfilling changes the distribution of cells within the chamber.
The sample should fill the counting area smoothly by capillary action. Liquid should not flow into the surrounding channels.
Ensure that the coverslip is positioned correctly and that the hemocytometer is clean.
Inconsistent Boundary Rules
Cells touching the grid borders must be handled consistently.
Including border cells in one square and excluding them in another can introduce double counting or undercounting.
Use one predefined boundary rule throughout the experiment.
Incorrect Focus
Poor focus changes the apparent appearance of cells.
Unstained cells may appear darker than expected, while debris may appear similar to intact cells.
Use the same focus procedure and magnification for all samples. Check more than one focal plane when cell boundaries remain unclear.
Incorrect Dilution Factor
A frequent calculation error is forgetting that a 1:1 mixture with Trypan Blue creates a dilution factor of 2.
The opposite error can occur with automated instruments that already correct for dilution. Applying an additional factor manually would overestimate the cell concentration.
Check how the result is calculated before recording or reporting the final value.
Troubleshooting Trypan Blue Cell Counting
| Observation | Possible cause | Recommended action |
|---|---|---|
| Viability decreases during the counting session | Stained samples remain exposed for different periods | Prepare and count samples sequentially |
| Counts differ between chambers | Incomplete mixing, settling, or poor chamber loading | Remix the suspension and reload the chamber |
| Many small blue particles are visible | Debris or cellular fragments | Apply consistent size and morphology criteria |
| Cells are unevenly distributed | Air bubbles, overfilling, underfilling, or cell settling | Clean and reload the chamber |
| Viability is unexpectedly low | Prolonged staining, harsh handling, or poor culture condition | Repeat the count using a fresh aliquot and controlled timing |
| Viability is unexpectedly high | Dead cells or debris may have been excluded | Review the classification criteria |
| Large aggregates are present | Incomplete detachment or insufficient dispersion | Optimize cell preparation before staining |
| Results vary between operators | Different focus, border rules, or classification criteria | Standardize training and counting rules |
Manual Trypan Blue Counting Versus Automated Cell Counting
Trypan Blue can be used in manual hemocytometer workflows and in instruments designed to analyze dye-exclusion samples.
Each approach has advantages and limitations.
Manual Hemocytometer Counting
Manual counting requires a microscope and hemocytometer.
Its main advantages include:
- Low equipment requirements.
- Direct visual inspection of the sample.
- Ability to observe morphology and cell clumps.
- Flexibility when working with unusual cell types.
- Immediate identification of debris or chamber-loading problems.
Manual counting also has limitations:
- It is operator-dependent.
- It can be time-consuming.
- Only a relatively small number of cells are examined.
- Borderline objects may be classified differently by different analysts.
- Arithmetic and transcription errors can occur.
Manual counting works well for occasional measurements and for samples that require direct visual assessment.
Automated Cell Counting
Automated counters can process stained samples rapidly and apply predefined image-analysis rules.
Potential advantages include:
- Faster routine counting.
- Automated viability calculations.
- Reduced manual arithmetic.
- Digital images and stored results.
- Consistent processing after suitable settings have been established.
- Greater convenience when many samples must be analyzed.
However, automated counting still requires method control.
The instrument must correctly distinguish cells from debris, fragments, bubbles, and aggregates. Size thresholds, focus, brightness, and segmentation settings can affect the result.
A setting that performs well with one cell line may not be suitable for another.
Representative samples should be reviewed during method setup, including:
- High-viability samples.
- Low-viability samples.
- Different cell concentrations.
- Samples containing debris.
- Samples containing aggregates.
- Cells with different sizes or morphologies.
Automation can reduce operator workload, but it does not eliminate the need for proper sample preparation and result review.
Limitations of the Trypan Blue Exclusion Assay
Trypan Blue is a useful routine method, but it does not provide a complete evaluation of cell health.
Membrane Integrity Is Not Cell Function
The assay evaluates whether the plasma membrane excludes the dye.
It does not directly measure:
- Metabolic activity.
- Mitochondrial function.
- ATP concentration.
- Gene expression.
- Protein synthesis.
- Proliferative capacity.
- Long-term survival.
A cell may exclude Trypan Blue but still have impaired metabolism or limited ability to divide.
Early Apoptotic Cells May Remain Unstained
During early apoptosis, cells may retain an intact plasma membrane.
These cells can exclude Trypan Blue and be classified as viable even though the apoptotic process has already started.
Trypan Blue also cannot determine whether a stained cell died through apoptosis, necrosis, or another mechanism.
Researchers investigating apoptosis should use an assay designed to detect specific apoptotic markers.
The Canvax Apoptosis Assays range can support studies that require more detailed characterization of cell death.
Results Are Time-Dependent
Trypan Blue exposure must remain short and controlled.
Longer exposure can increase dye uptake and reduce the measured viability.
This makes timing especially important when many samples are counted manually.
Results Depend on Sample Quality
A Trypan Blue count assumes that the sample contains a representative, well-dispersed cell suspension.
Clumps, debris, bubbles, and sedimentation can make the result less reliable.
Results Can Be Operator-Dependent
Manual classification requires judgement.
Analysts may differ in how they classify weakly stained cells, small fragments, border cells, and clusters.
Training and standardized procedures help reduce this variability.
When to Use Another Cell Viability Assay
Trypan Blue is suitable when the objective is to obtain a rapid estimate of cell concentration and membrane integrity.
Another assay may be more appropriate when researchers need to:
- Detect early apoptosis.
- Measure metabolic activity.
- Analyze many samples in multiwell plates.
- Distinguish different cell-death populations.
- Evaluate mitochondrial activity.
- Measure long-term proliferation.
- Study complex or heterogeneous cultures.
- Monitor cell health without relying only on membrane integrity.
Combining Trypan Blue with a complementary method can provide a more complete understanding of cell condition.
For example, a researcher may use Trypan Blue to normalize the number of viable cells at the beginning of an experiment and then use a metabolic or apoptosis assay to evaluate the biological response.
No single viability assay answers every question. The selected method should match the experimental objective.
How to Choose a Trypan Blue Solution
A suitable Trypan Blue reagent should support a consistent and straightforward workflow.
Concentration
A 0.4% solution is commonly used for routine dye-exclusion counting.
Equal-volume mixing with the cell suspension provides a simple protocol and a clear dilution factor.
Ready-to-Use Format
A ready-to-use solution removes the need to weigh, dissolve, adjust, or filter the dye before routine counting.
This reduces preparation time and helps maintain consistency between experiments.
Sterility
A sterile solution is particularly useful when working near active cell culture workflows.
Good laboratory practice should still be followed:
- Keep the container closed when not in use.
- Use clean pipette tips.
- Avoid returning dispensed reagent to the original container.
- Prevent contact between the bottle and potentially contaminated materials.
Storage
Always follow the storage conditions stated in the current product documentation.
Protect the reagent from contamination and inspect the solution before use.
Do not use the product when the container is damaged or when the solution shows an unexpected appearance.
Canvax Trypan Blue Solution, 0.4%
Canvax Trypan Blue Solution, 0.4% is a sterile, ready-to-use reagent for viability assessment through the dye exclusion method.
The product is supplied as:
- 0.4% Trypan Blue solution
- Sterile and ready to use
- 100 mL format
- Storage at 15–25°C
The solution supports routine research workflows in which cells with intact membranes must be distinguished from blue-stained, membrane-compromised cells.
For consistent results:
- Prepare a homogeneous cell suspension.
- Mix the cells gently with the dye.
- Avoid air bubbles.
- Use freshly prepared stained aliquots.
- Begin counting within approximately 1–3 minutes.
- Apply the same reading interval across samples.
- Include the correct dilution factor in the calculation.
Visit the Canvax Trypan Blue Solution, 0.4% product page for product information and ordering details.
Frequently Asked Questions About Trypan Blue
What is Trypan Blue used for?
Trypan Blue is used to estimate the percentage and concentration of viable cells in a cell suspension.
Do viable cells stain blue?
No. Viable cells with intact plasma membranes normally exclude Trypan Blue and remain bright or unstained during the short assay period.
Which cells stain blue?
Cells with compromised plasma membranes absorb Trypan Blue and appear blue under a microscope.
What concentration of Trypan Blue is commonly used?
A 0.4% Trypan Blue solution is commonly used for routine cell counting and viability assessment.
What is the standard Trypan Blue dilution?
A common protocol mixes equal volumes of 0.4% Trypan Blue and cell suspension. This creates a dilution factor of 2.
How quickly should cells be counted?
Begin counting shortly after mixing, ideally within approximately 1–3 minutes. Use freshly prepared stained aliquots and maintain the same timing across samples.
What happens when cells remain in Trypan Blue for too long?
Prolonged exposure may damage viable cells or increase dye uptake. This can produce an artificially low viability result.
How should cells and Trypan Blue be mixed?
Mix gently by pipetting until the cells and dye are evenly distributed. Avoid vigorous agitation and air bubbles.
How is viability calculated?
Use:
Viability (%) = Viable cells ÷ Total cells × 100
How is cell concentration calculated?
For a standard Neubauer hemocytometer:
Cells/mL = Average cells per large square × dilution factor × 10^4
Can Trypan Blue detect early apoptosis?
Not reliably. Early apoptotic cells may retain an intact membrane and exclude the dye.
Can Trypan Blue distinguish apoptosis from necrosis?
No. The assay detects membrane permeability but does not identify the specific mechanism of cell death.
Why do replicate counts sometimes differ?
Differences may result from cell settling, poor mixing, clumping, chamber loading, bubbles, focus, or inconsistent classification.
How should Canvax Trypan Blue Solution, 0.4% be stored?
Store the product at 15–30°C according to the current product documentation.
Reliable Cell Counting Starts with a Consistent Workflow
Trypan Blue remains a practical and accessible method for routine cell counting and viability assessment.
Its value lies in its simplicity. Viable cells remain unstained, while cells with compromised membranes appear blue.
Reliable results depend on consistent handling.
Prepare a representative single-cell suspension. Resuspend the cells before sampling. Mix gently with the dye. Avoid bubbles and uneven chamber loading. Apply clear counting rules and include every dilution factor in the final calculation.
Most importantly, use freshly prepared samples and begin counting shortly after mixing, ideally within approximately 1–3 minutes.
A difference of only a few minutes in staining time can change the apparent number of blue cells and reduce comparability between samples.
For a sterile, ready-to-use reagent for routine dye-exclusion workflows, explore Canvax Trypan Blue Solution, 0.4%.