8. Two hundred pi of isooctane is added to the vials to 
prevent evaporation to dryness. The extract is blown 
down to 0.20 jul. This gives an overall 25 x concen¬ 
tration (5 ml to 0.2 ml). 
9. A procedural blank was prepared in triplicate for 
each experiment. Each contains the extracting 
solvent and internal standard but no sediment 
samples. Isooctane is added after the blanks 
have been sonicated and blown down. For LC 
analysis, tetrahydrofuran was substituted for 
the isooctane. These procedures are summarized 
in Tables 9 and 10. 
TABLE 9. FIELD SAMPLE HANDLING 
Procedure 
Precleaning 
Surface Grab 
Sampler 
On-board 
High Pressure 
Water Hose 
Obtain Core within 
Grab Sampler 
Use brass tube precleaned 
by acid etch, soap, water. 
Swabbed with abrasive 
between samples. 
Storage 
Use baked glass bottles, 
aluminum cap liners. 
Hold for 14 days at 4°C. 
Isopiestic 
Dehydration 
Two 48-hour periods. 
Closed system 
Sample 
Homogeneity 
Sample grinding with 
baked glass mortar and 
pestle. 
Storage 
Dried sample stored at 
4 °C. 
52 
