5. Measurement
AUTOMATIC PETRO PYROLYSIS MERCURY ANALYZER – MERCURY/PE-1000
25
No.600-2111-09
Preparation of standard solutions
While various methods can be used to fix standard samples, Nippon Instruments
Corporation obtained the best results using L-cysteine solution. However, even using L-
cysteine solution stability can degrade with age or due to being stored in a warm place
for a long time. Ensure solutions are stored in a cool dark place.
(Preparation instructions)
(1) 0.001% L-cysteine solution
Weigh 10 mg of L-cysteine (not cystine), drips it into a 1,000-mL flask, and then
adds water and 2 mL of guaranteed-grade concentrated nitric acid.
Shake it well to make a uniform solution, and bring the total volume to 1,000 mL.
Ensure to store it in a cool dark place.
(2) As a general rule use commercially available 1000-ppm standard solutions provided
with a traceability certificate.
If it is not available, weigh 67.7 mg of HgCl
2
, and dissolve it in a 0.001% L-cysteine
solution to bring the volume to 500 mL. A mercury solution with a concentration of
100 ppm will then be the result.
(3) Extract 1 mL of 1000-ppm solution, and dilute it with 0.001% L-cysteine solution to
bring the volume to 100 mL. A 10-ppm standard sample will then be the result. By
diluting it in a similar fashion, standard samples of any concentration can be
prepared. However, when very dilute solutions are prepared any mercury present in
the reagent or redistilled water should be taken into consideration.
(Note) Diluted solutions, standard solutions with a concentration of 100 ppm, and
standard solutions with concentrations of 10 ppm or less should be freshly
prepared after periods of six months, a year, and six months have respectively
elapsed.
(Note) When freshly preparing standard solutions use the same volumetric flask.
(Note) Before using a new volumetric flask wash it with acid. In particular, when
preparing any solution with a concentration of 1 ppm or less, carefully wash the
flask with acid to ensure that its tap is thoroughly cleaned.
