grab samples

Chelating reagent: ammonium pyrrolidinedithiocarbamate (APDC) or sodium diethyldithiocarbamate
(DEDC). Make up a 5% solution with deionized-distilled water. Extract at least twice with methyl
isobutyl ketone (MIBK).
Methyl isobutyl ketone (MI BK) (distilled).
C. Extraction
(I) Pl ace 220 ml of solution in a SOO-ml acid-washed separatory funnel. Add 2 ml of cheiating
reagent and add 5 ml ofMIBK.
(2) Shake thoroughly for about 3 min and save the upper (extract) layer for analysis.
D. Analysis
For flame conditions, adjust the spectrometer settings as above. It may be necessary if the metal
concentrations are very low to use the flameless attachment of the atomic absorption spectrometer. Check
manufacturer's handbook.
6.9 Vanadium (Atomic Absorption)
Note: This solution can be used for both vanadium and molybdenum determinations.
I. Concentrations
Average river water < I ttg/ /
Average nearshore sediment 130 mg / kg
Sea water = 1-3 ttg/ /
The disso lved sediment as prepared in Section 6.2 is analyzed by flame atomic absorption with the
following operating parameters:
A. Detection Limits
Flame: 0.05 mg/ / (solution) (= SO mg / kg in sediment)
B. Working Range
Linear response of the spectrometer can be expected up to 140 mg / / (solution) (= 140 g/kg in
sediment).
C. Interferences
Addition of 0.5% AI (2.5 g AICI) in 100 ml) increases the sensitivity. Add 0.2 ml of AI reagent per 10
ml of sample, blank(s), and standard(s).
D. Instrument Parameters
Wavelength: 318.4 nm
Fuel: nitrous oxide/acetylene
Check manufacturer's handbook
Fla me: red ucing (rich, red)
II. Solvent Extraction
This is necessary for the low concentrations found in seawater.
A. Detection Li m i ts
Flame: 0.005 mg / /(solution)
Flameless: 0.0007 mg / /(solution)
37