Immediately upon completion of the RF heating process, three sets of shavings obtained from the treated part of each pole section were placed in a glass dish in a fume hood and sprayed with chromotropic acid solution.
Chromotropic acid. -- 2.0 g of 4,5-di-hydroxynaphthalene-2, 7-disulfonic acid was dissolved in 400 mL of 0.5 M sulfuric acid.
None of the samples showed any reaction with chromotropic acid, indicating that there was no detectable hexavalent chromium ([less than] 15 ppm of Cr(VI)) (13,14).
Comparing the chromotropic acid data with the spectrophotometer analysis, some discrepancies can be seen in Tables 2 through 4.
The chips recovered from the pole sections were also tested using chromotropic acid at different time intervals (Table 6).