How do I perform a total Chromium analysis in plant, soil, and water using Diphenyl Carbazide method while keeping low detection limits?

I have tried methods a few methods, see attached, but in each they require at least a 5x dilution of the sample before analysis and then again a dilution in color preparation. When I try to avoid diluting with distilled water and using highly concentrated basis to increase the pH of digested sample the color quickly dissapears upon addition of diphenyl carbazide. See methods I have been working on attached and in "Determination of total chromium in tannery waste water by inductively coupled plasma-atomic emission spectrometry, flame atomic absorption spectrometry and UV – visible spectrophotometric methods". Also I do not have access to a chromatography column so am trying to do this without preconcentration and isolation by chromatography.