Our lab wants to purchase IL-6 and TNF-α ELISA kits. How should we choose between domestic and imported options?

Import lead times are currently highly volatile. For common brands with stock available, delivery takes 1-3 weeks; for less common targets, it may take 6-8 weeks. Before placing an order, be sure to have the distributor confirm whether the item is in domestic stock or needs to be sourced from overseas. In terms of price, imported single-factor 96T kits are generally significantly more expensive than domestic ones. The specific range is affected by the distributor, tax points, and promotions. It is recommended to inquire using a full kit plus supplemental strip model. If testing 3 factors with 60 samples, you can apply for trial samples from several suppliers and use the same batch of rat serum for high and low value dilution linearity to check the measured recovery rate. Note that rat serum inflammatory factor ELISA matrix effects are pronounced. Some kits perform fine with human samples, but may not be accurate with native rat serum.

When selecting, implement "inter-batch variation" and "linear range" in three points: First, ask for the intra-assay/inter-assay precision from the kit instructions; generally, intra-assay CV should be below 10%, and inter-assay below 15% is more reliable. Second, ask for detection data or recovery rates from native rat samples, not just recombinant protein standard curves. Third, clarify whether the calibrators can be split into strips and whether the standards are sufficient for a single experiment, to avoid wasting half a box. Among domestic brands, Lianke and Xinbosheng both offer common rat inflammatory factor indicators; imported R&D Quantikine series have a stable reputation but are expensive. It is recommended to use high- and low-value rat serum for parallel dilution to see whether the measured values decrease linearly with dilution, which is more practical than looking at promotional parameters.

For 60 samples, using a 96T plate can indeed easily leave unused wells. Prioritize detachable strip plates; do not buy fixed, non-detachable whole plates. Leading domestic brands such as Lianke and Xinbosheng have controlled inter-batch variation well in recent years, with nominal inter-batch CV mostly around 10%. Imported brands like R&D and Invitrogen generally report more detailed data, but fluctuations vary across different analytes. Don't just ask "is the difference big?" Have suppliers provide linear range, inter-batch CV, and recovery data for the corresponding rat serum/plasma. If you are doing pre- and post-model comparisons, it is best to lock the same brand and same lot number for the same analyte to avoid drift caused by changing lots. If the budget is tight, you can first use domestic products for initial screening, then use imported products to retest key conclusions.

Domestic kits are cheaper, but batch-to-batch variability should be noted; imported kits are expensive due to their stability. It depends on the data requirements of the experiment.

First, use the imported kits to retest a few samples against the domestic kits. If the deviation is not significant, we can switch.