Page 101 - Geochemistry of Oil Field Waters

EMISSION SPECTROMETRY 89

standard), 20 ml of n-propanol, and sufficient distilled water to adjust the
volume to 50 ml at ambient temperature. For optimum accuracy, prepare
duplicate or triplicate samples.
Aspirate and excite the sample, develop the plate, and read the plate as
suggested above. Determine the relative intensity ratios for the following: Ba
4554.03/La 4429.90; B 4995.46/La 4429.90; Mn 5152.20/La 4086.72; Sr
4215.52/La 4086.72; and Fe 5198.80/La 4086.72.

Calculations. Refer the calculated ratio to the appropriate calibration curve
to determine milligrams of tested ion in the sample. Convert this value to
milligrams per liter by use of the following equation:
mg from curve x 1,000
ml sample = mg/l

The relative intensity ratios for other line pairs can be calculated and used if
desired. The precision and accuracy of the method are approximately 2-3%
and 4-696, respectively, for strontium and barium; and 54% and 10-1196,
respectively, for boron, iron, and manganese.

Beryllium

Beryllium forms a complex with acetylacetone which can be extracted
into chloroform from an aqueous solution. The chloroform extracted is
aspirated into a plasma arc, and the beryllium I1 line at 3131.07 A is read.
An apparent carbon line at 3036.3 A is used for an internal standard.

Reagents. Spectrographic plates, Eastman Kodak Type SA No. 1.
Standard beryllium stock solution: dissolve 1.00 g of fused metallic beryl-
lium (spectroscopic grade) in a small amount of 6N hydrochloric acid and
dilute to 1 liter with 1% hydrochloric acid. 1 ml contains 1 mg of beryllium.
Standard beryllium solution: prepare a standard by transferring a suitable
aliquot of the standard stock solution to a 1-liter volumetric flask and
diluting to volume with 1% hydrochloric acid. The standard prepared will
depend upon the resolution and dispersion of the spectrograph. However, for
many instruments, a 0.01 pg/ml solution should be adequate.
EDTA solution: dissolve 10 g of disodium ethylenediaminetetraacetic acid
and 2 g of sodium hydroxide in water and dilute to 100 ml.
Synthetic brine solution: dissolve 80 g of sodium chloride, 30 g of calcium
chloride, 10 g of magnesium chloride, 5 g of strontium chloride, and 3 g of
potassium chloride in distilled water that is saturated with carbon dioxide
and dilute to 1 liter.
Hydrochloric acid, concentrated.
Sodium hydroxide, 0.5N.
Chloroform.
Acetylacetone.