Customer ReviewsforSigma-Aldrich Corp

I am a researcher working at the ************************** ***** but used to work in *****, *******, and ***************** for most of my academic career. Our work utilizes a spin trap called ******************************** (DMPO); a fine and expensive reagent that I have extensive experience working with it as my publications indicate. Over the past few years, we have received DMPO with variable amounts of stable free-radical contamination. The presence of this contamination leads to redox cycling and ruins our experiments. We have indicated this to the local vendor/agent who has contacted the company with our complaint and evidence of contamination. We received no resolution to the issue. Thousands of dollars are wasted over disrupted experiments with tens of thousands of dollars wasted due to wasted efforts and times that yielded doubtful results.We are very frustrated not only because of money and time wasted over a very simple right: obtain a pure reagent!!!; but also due to ignoring our repeated complaints!!Since we have no other ways to assess free radicals experimentally, and our samples are obtained from human samples and animals after being groomed for a very long time and at particular conditions; the bad DMPO batches led to huge financial, efforts, and time losses. This cannot be acceptable, especially from a reputable company like the vendor.We have been complaining about this for several months without any satisfying answers. In fact, we just received a different batch (EGP ******) and were shocked by the huge amount of impurities as evident in the dark orange color of the reagent and the *** signal (given in a report filed to the local agent and company). This again will hamper our ongoing projects and will certainly affect our results negatively.It is really sad that I have never encountered such a problem during my long tenure working in the U.S., *****, and Europe. This can only be explained in terms of destination-based discrimination!