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Cat. No.
500 x 50µl Reactions

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BioMix™ Red is a complete ready-to-use 2x reaction mix containing an ultra-stable Taq DNA polymerase. It contains an additional inert red dye that permits easy visualization and direct loading onto a gel.

Product Highlights

  • Convenient format - pre-mixed, pre-optimized 2x solutions
  • Versatile - suitable for routine PCR applications
  • Ready-to-use - reduces contamination risks
  • Suitable for TA cloning - leaves 'A' overhang
  • Direct gel loading - eliminates the need for further processing following reaction completion

Product Description

BioMix™ Red is a complete ready-to-use 2x reaction mix containing a stable Taq DNA polymerase. It contains an additional inert red dye that permits easy visualization and direct loading onto a gel. There is no need to add loading buffer as the mix is of sufficiently high density to sink to the bottom of the gel. The red dye migrates like a 350 bp fragment on a 2% agarose TAE gel (or 600 bp on a 1% agarose).

BioMix Red has been developed to perform PCR assays of many common genomic and cDNA templates; the user has simply to add water, template and primers. It reduces the time required to set-up reactions, thereby minimizing the risk of contamination. Reproducibility is ensured by reducing the number of pipetting steps that can lead to errors.

BioMix Red is supplied with additional MgCl2 solution should any fine adjustments be required.


  • Routine PCR applications
  • TA cloning
  • High throughput

PCR Enzyme Guide

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PCR Selection Chart

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100 Reactions

500 Reactions

BioMix™ Red

2 x 1.25 mL

10 x 1.25 mL

50 mM MgCl2 Solution

1.2 mL

1.2 mL


  • BIO-25005: 100 x 50 µL Reactions: 2 x 1.25 mL
  • BIO-25006: 500 x 50 µL Reactions: 10 x 1.25 mL


  • 2x

Storage & Stability

All components should be stored at -20°C upon receipt for optimum stability. Repeated freeze/thaw cycles should be avoided. When stored under the recommended conditions and handled correctly, full activity of the reagents is retained until the expiry date indicated on the outer box label.

Alternatively, BioMix Red can be stored for up to up to 2 weeks at +4°C.

Shipping conditions

On Dry Ice or Blue Ice.


No, the dyes and composition of the Red Reaction Buffers and Mixes are such that the samples will sink easily into the well and the samples can be clearly seen, thus no loading buffer is required to load your samples on an agarose gel.

The dye present in the Red Mixes or Red Reaction Buffer does not interfere with PCR product isolation procedures or subsequent applications like sequencing. An exception is the quantification of PCR products in colored buffers with photometric methods or fluorescence assays. We cannot exclude the impact of the dye on quantification results and suggest the purification of these samples, for instance with ISOLATE II PCR & Gel kit or SureClean Plus.

Meridian's mixes contain magnesium chloride at the following concentrations (please see table below). An additional tube of 50 mM MgCl2 solution is supplied with each mix to facilitate further optimization if required.

 Meridian Mix Final Magnesium Concentration
ACCUZYME Mix  2.0 mM.
BioMix / BioMix Red  2.5 mM.
ImmoMix / ImmoMix Red  3.0 mM.
BIO-X-ACT Short Mix  2.0 mM.
MangoMix  2.5 mM.
MyTaq  3.0 mM.
RANGER  1.5 mM.

At Meridian we pride ourselves in supplying high-quality polymerases to suit your requirements. To aid your selection of the most suited enzyme for your specific applications, please see our enzyme selection tool.

All our polymerases are guaranteed for a period of 12 months from the date of purchase. These should be stored at -20°C during this time for optimal retention of activity.

Please Note: We do not recommend the storage of our polymerases at -80 °C as ice crystals could form on the active site, which may affect or destroy the activity of the enzyme.

PCR can be a challenging technique, with various parameters to optimize to achieve the best results. If you are having problems, these could be easily resolved by addressing a few issues. Please see our PCR troubleshooting guide for suggestions and help with your specific problems.

Observation Recommended Solution(s)
No or low PCR yield  Enzyme concentration too low – increase the amount of enzyme in 0.5 U increments.
 Primers degraded – check quality and age of the primers.
 Magnesium concentration too low – increase concentration in 0.25 mM increments with a starting  concentration of 1.75 mM.
 Primer concentration not optimized. Titrate primer concentration (0.3-1 µM); ensuring that both  primers have the same concentration.
 Template concentration too low – Increase concentration of template.
 Perform a positive control to ensure that the enzyme, dNTPs and buffers are not degraded and/or contaminated.
Multiple Bands  Primer annealing temperature too low. Increase annealing temperature. Primer annealing should be at least 5°C below the calculated Tm of primers.
 Prepare master mixes on ice or use a heat-activated polymerase.
 For problems with low specificity. Try adding 3% DMSO (not supplied) to improve specificity.
Smearing or artifacts  Template concentration too high. Prepare serial dilutions of template.
 Too many cycles. Reduce the cycle number by 3-5 to remove non-specific bands.
 Enzyme concentration too high - decrease the amount of enzyme in 0.5 U increments.
 Extension time too long. Reduce extension time in 0.5-1 minute increments.

These terms refer to parameters to be considered when performing PCR and are important features in selecting the correct enzyme for your needs. Understanding what they mean is therefore crucial: Yield: The amount of DNA produced in a PCR reaction. Fidelity: The accuracy of the enzyme at incorporating the correct dNTP to the elongating DNA strand. Processivity: The length of time a polymerase is associated with the template and therefore the size of fragment which can be amplified. Specificity: A measure of the unwanted by-products generated in a reaction.

One unit is defined as the amount of enzyme that incorporates 10 nmoles of dNTPs into acid-insoluble form in 30 minutes at 72°C.

All Meridian polymerases are available in the convenient format of a 2x master mix, containing all the reagents and additives necessary to perform successful PCR, with the exception of template, primers and water. This formulation not only provides a convenient and hassle-free PCR setup, but also significantly reduces the chances of human error, inaccuracies and contamination by reducing the pipetting steps required.

We recommend a final reaction volume of 50 µL, this requiring the use of 25 µL of the 2x master mix and to make up to 50 µL using template, primers and PCR grade water.

Whilst the exact composition of the mixes is proprietary information, all mixes are made up of reaction buffer, magnesium, dNTPs, polymerase and additives, designed to keep the polymerase stable in the mix, as well as provide the optimal conditions for PCR.

The MyTaq HS DNA polymerase works very well with difficult samples like GC rich or bisulfite converted DNA. Especially the hot-start is important, as it decreases primer dimer and unspecific amplification. We would suggest to start with the recommended protocol. If optimization is needed, we would suggest to optimize the annealing temperature. Due to the degraded DNA after bisulfite conversion it may be useful to increase the amount of template and polymerase.

All Meridian PCR mixes come supplied at a 2x concentration, requiring the user simply to add template, primers and PCR grade water to a final concentration of 1x.

If possible, we would recommend an additional cleanup of affected samples, for instance, customers had very good experiences with the clean-up of samples containing humic acids with SureClean Plus. Alternatively decreasing the template concentration will help to minimize the amount of inhibitors. The amount of primer can be increased, but do not exceed the suggested limits.