Page 97 - Geochemistry of Oil Field Waters

EMISSION SPECTROMETRY 85

hydrochloric acid. Evaporate these acid solutions to dryness, dissolve the
residues in distilled water, combine, and dilute to 1 liter with distilled water.
Hydrochloric acid, concentrated.
n-Propanol.

Equipment. The necessary equipment includes a spectrograph; a d.c. arc
source, 18-A minimum; a plasma arc assembly; a plate-developing machine; a
microphotometer; 50-ml volumetric flasks; 10-ml microburets; pipets; and
spectrographic plates, Eastman Kodak Type 1-N.

Spectrochemical excitation conditions. The conditions which are used to
determine barium, boron, iron, manganese, and strontium are as follows:
Source, d.c. arc.
Current, 18-25 A (keep constant).
Voltage, 220 d.c.
Pre-exposure time, 5 seconds.
Exposure time, 15 seconds.
Spectral region, 3200-5200 8, first order and second order.
Dispersion, reciprocal linear 8.21 8/mm first order, 4.02 8/mm second
order or better.
Plasma arc assembly.
Helium lift gas, 7 liter per minute.
Helium tangential gas, 60 liter per minute.
Atomizer, Beckman Model 4030 with medium-bore capillary.
Arc length above orifice, 7 mm.
Full arc length, anode to cathode, 18 mm.
Portion of arc viewed, 2 mm above orifice.
Orifice electrodes; lower anode, Ultra Carbon 106 drilled to 3.97 mm in
center hole, tapered to 9.53 mm at bottom; center ring, neutral Ultra Carbon
861 drilled to 5.95 mm center hole, tapered to 9.53 mm at bottom.
Cathode electrode, vertical position, Ultra Carbon 6.35 mm graphite rod
with pointed tip.
Slit, 20-p.
Filter, 3-step.

Spectrographic plate development conditions: 5 minutes in Eastman Kodak
D-19 at 2OoC with constant agitation; 30 seconds in stop bath at 3OoC with
agitation; 5 minutes in Eastman Kodak rapid fixer and hardener solution at
2OoC with constant agitation; 30 minutes in water rinse with constant fresh
supply of water; 30 seconds rinse with distilled water; and 30 minutes in
constant air bath to dry.

Microphotometer criteria. Slit, 12 p wide and 0.5 mm high.
Read the background and intensity of the following lines: Ba, 11, 4554.03