DETERMINATION SF TOTAL CHROMIUM IN MARINE SEDIMENT REFERENCE MATERIALBCSS-1

The determination of Cr in National Research Council of Canada Marine Sediment Reference Material BCSS-1 is addressed. Mixed acid digestions utilizing HF. HClO4 and HNO3 were investigated. Single microwave assi sted digestions in closed vessels at medium pressures (8 bar) were ina ppropriate (80% recovery). Double digestion at moderate pressure and d igestions at high pressure (70 bar) or lengthy open-beaker hot plate d issolutions resulted in 93 +/- 5% recovery of certified Cr content. Fl ame atomic absorption and inductively coupled plasma atomic emission s pectrometry were used for quantitation. In all cases, the method of st andard additions was necessary to eliminate the approximately 10% enha ncement in response relative to unmatched standards. Compared to a cer tified content of 123 +/- 7 mu g/g (mean and standard deviation), valu es of 116 +/- 6 were obtained using an open beaker digestion: 114 +/- 5 using a double microwave digestion at 8 bar; 113 +/- 2 for microwave digestion at high pressure and 111 +/- 4 at high pressure (81 bar) wi th triple microwave digestion in a Parr bomb. No acid dissolution proc edure is adequate for Cr in this sample although recovery of total Cr is complete from National Institute of Standards and Technology Buffal o River Sediment (SRM 2704).