TABLE 1.—Summary of analytical conditions—Continued 
Procedure 
determination Average blanks, 
Extraction limit in sample, as measured in 
Element Instrument Instrument conditions procedure ug/g ug/g in solution 
Pyrolytic curtin tube 
Normal gas flow (high) 
W.1.=318.4 nm 
Slit=0.7 nm. 
ANS SS Flame AA.—-----—— Oxidizing; air-acetylene Butyl acetate-------------— 1 -O1 
flame 
W.1.=213.9 
Slit=0.7 nm. 
and digested overnight with 5 mL of HC1O,, 5 mL 
of HNOs, and 13 mL of HF at approximately 140 
°C. The covers were removed, and the temperature 
was increased to between 180° and 190 °C, first 
producing fumes of HC1O, and then evaporating 
the solution to dryness. The residue was dissolved 
and diluted to exactly 25 mL with 8 N HCl. This 
solution is referred to as stock solution A. 
Two blanks containing all reagents were analyzed 
along with samples. All reagents were analyzed for 
contaminants before use, as is always necessary. 
The Canadian reference sediment standard 
MESS-1 was analyzed in each set of samples. A 
series of solutions was prepared that approximated 
the concentration levels expected in the samples; 
this series was used as the standard in calibrating 
the inductively coupled plasma (ICP) spectrometer 
and atomic absorption (AA) spectrophotometer. 
PREPARATION OF STOCK SOLUTION B 
Stock solution B was made by adding 10 mL of 
butyl acetate (distilled to remove impurities such 
as copper) to 15 mL of stock solution A in a 60- 
mL separatory funnel. This solution was then 
vigorously agitated by an automatic shaker for 6 
minutes to extract iron. The layers were separated, 
and the extraction step was repeated with an addi- 
tional 10 mL of butyl acetate. The aqueous layer 
was evaporated to dryness at 150 °C in a 50-mL 
beaker. The residue was dissolved and diluted to 
25 mL with 1 N HCl. 
BARIUM 
The measurements for Ba were made by ICP 
spectrometry by using 2 mL of stock solution A 
diluted to 4 mL with distilled H,0. 
ALUMINUM, IRON, CHROMIUM, NICKEL, AND VANADIUM 
Concentrations of Al and Fe were determined by 
ICP spectrometry by using 1 mL of stock solution 
A diluted to 10 mL with H,O. The measurements 
for Cr, Ni, and V were made by injecting 20 pL of 
diluted (1:10) stock solution A into a graphite- 
furnace AA spectrophotometer. 
LEAD, COPPER, AND CADMIUM 
Fifteen mL of 0.5-percent ( weight : volume) 
diethyldithiocarbamic acid diethylammonium salt 
(DDTC) in chloroform were added to 10 mL of solu- 
tion B in a 60-mL separatory funnel and mixed for 
10 minutes by an automatic shaker. The chloro- 
form layer was drained into a 30-mL beaker, and 
the aqueous layer washed with 10 mL of chloro- 
form. The second chloroform layer was combined 
with the first, and the total volume of chloroform 
was evaporated to dryness at 90 °C. The organic 
matter was destroyed by adding 0.1 mL of concen- 
trated HNO, and was evaporated to dryness. This 
residue then was dissolved in 2 mL of warm 1 N 
HCl. The beaker was rinsed four times with 2 mL 
portions of distilled H,O, and the solution was 
transferred to a small polyethylene container. The 
measurements for Pb, Cu, and Cd were made by 
injecting 20 pL of the final solution into a graphite- 
furnace AA spectrophotometer. 
MANGANESE AND ZINC 
The measurements for Mn were made by ICP 
spectrometry with a solution made by diluting 
2 mL of stock solution B to 4 mL with H,O. Zinc 
was measured by flame AA directly from stock 
solution B. 
