Application Note HG/FO 23 Fresh Salmon Summary Precise and rapid determination of total mercury in fresh salmon can be performed using a Direct Mercury Analyzer. Such an instrument requires no sample wet chemistry or pre-treatment. Once a weighed sample portion is introduced into the instrument, analysis is complete within six minutes. Direct analysis of mercury, using the integrated sequence of Thermal Decomposition, Catalyst Conversion, Amalgamation, and Atomic Absorption Spectrophotometry, is described in EPA 7473 and is validated for laboratory as well as field analysis. Instrumentation DMA-80 Package Complete Terminal 640 / Terminal 1640

Terminal Software / PC Version Software

Nickel Sample Boats Additional:

Analytical Balance; Spatula, Pipette, Volumetric Flask (10 mL)

Calibration Calibration working standards are freshly prepared from bulk solution or from an NIST traceable Atomic Absorption bulk solution of 1000 ppm (mg/Kg) Hg in 5% HNO3. Calibration working standards are obtained by quantitative transfer and dilution of aliquots from the bulk solution with 4% HCl. Sample Weight 50 mg 190 mg

Due to the organic nature of the sample it is recommended not to exceed 200 mg. Procedure

1. Place the sample boat on balance and tare it.

2. Mix and weigh out sample and place inside boat.

3. Introduce the boat into the autosampler tray.

4. Start the DMA-80 program and run to completion.

DMA-80 Program

STEP TIME TEMPERATURE1 0:01:00 200 C 2 0:02:00 650 C 3 0:01:00 650 C

Max Start T: 200 C Purge: 60 seconds

Results

Sample (mg/Kg) 1 0.129 2 0.136 3 0.115 4 0.127 5 0.139

Avg.: 0.129 ppm RSD: 5.14 % Conclusion The DMA-80 Direct Mercury Analyzer successfully analyzed the fresh salmon samples. Total analysis time per sample was less than 6 minutes, including the time needed to weigh and place each sample.