I'm trying to separate dextrose and lactate from the same solution, but am ending up with a peak showing up in the tail of dextrose. I am currently using a 0.1% H2SO4 mobile phase. I am using a 1:5 dilution of sample into CaOH TS, then a 1:3 dilution of that sample into high purity water. The original test sample contains dextrose and lactic acid, but I need to force the lactic to lactate, hence the CaOH TS. However, it seems as though dextrose doesn't like the high pH and produces this second peak. The peaks look good when my dilutions are freshly made, but are only good for about 40 minutes. Any ideas on how to make this work without having to develop two separate methods?