Is it more cost-effective to use premix for regular PCR or to buy dNTPs separately?

Conventional genotyping does not require as high amplification products as cloning sequencing, and Taq enzymes combined with domestically produced dNTPs can usually meet the requirements. The price difference is significant, and it is important to note that in addition to dNTPs, the premix also contains buffer solution MgCl2、 Enzymes, stabilizers, and some with loading dyes are not the same thing when comparing prices. If your sample type is fixed, primers and procedures are mature, buying dNTPs alone is completely feasible; If used by multiple people and with high requirements for standard operating procedures, pre mixed liquids can reduce human errors. My own habit is to use premix when there are many beginners or large sample sizes; Only experienced individuals who need to control the cost of single reaction will buy dNTPs and Taq separately. You can also ask the supplier for a small package trial to compare the success rate and repeatability of the two solutions in terms of typing.

When selecting domestic bulk dNTPs, I generally compare four points: whether purity is ≥99% and there are CoAs for more than three batches; whether it is labeled as free of DNase, RNase, and protease; whether the packaging bottle is low-adsorption and brown light-protected; and whether the quotation clearly states lead time and cold-chain shipping. For 10 mM bulk packaging, the quotes alone may differ considerably, but concentration accuracy also needs to be checked, and A260 testing may be necessary. Regarding arrival time, most domestic in-stock items take 1-3 days, while aliquoting or customization may take 5-10 working days. For 2× mix containing dNTPs, also check whether Mg2+ has been optimized and whether it is suitable for conventional PCR instruments. It is recommended to ask the supplier for a free sample, perform intra-batch replicates with your primers and 20-50 samples, calculate the genotyping concordance rate, and then decide which supplier to use long term.

200 responses per week, I suggest including labor and time when calculating the total cost first. Buying dNTPs with Taq enzyme alone may indeed be cheaper per reaction, but it takes at least 1-2 hours to prepare the system, package, and record batches per week. Moreover, the pH differences between different batches of dNTPs may cause fluctuations in the genotyping profile. The 2xmix containing dNTPs is easy to use, consistent between batches, and suitable for regular large quantities. Domestic 10 mM dNTPs are commonly packaged in large quantities of 1 mL, 5 mL, or larger, and usually take 1-3 days to arrive in stock. Customized large packaging may take 1-2 weeks; -The shelf life at 20 ℃ is generally 12-24 months, and requires confirmation of CoA with the supplier. If you are cost sensitive, you can buy large packages of dNTPs and self package them into single use quantities, but be sure to use low suction tubes and avoid repeated freezing and thawing for more than 5-10 times.

Buying dNTPs individually and subjecting them to repeated freeze-thaw cycles does indeed have an impact, especially dGTP and dCTP, which are relatively sensitive to repeated freeze-thaw and may lead to reduced amplification efficiency or nonspecific bands. My approach is to aliquot upon arrival, dividing each tube according to one week's usage, and store at -20°C; take out one tube at a time, thaw on ice, and do not refreeze after use. If used multiple times within a day, it can be temporarily kept at 4°C for a few hours, but overnight storage is not recommended. For domestic bulk packaging, check whether the pH is between 7.0-7.5, whether it is free of DNase/RNase, and request HPLC purity data. You can also perform a simple comparison: run PCR with the same batch of template using newly aliquoted dNTPs and dNTPs that have undergone 10 freeze-thaw cycles, and observe changes in Ct or band brightness; this will be more relevant to your own system than simply asking others.