1070-4272/04/7712-2025 C 2004 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 77, No. 12, 2004, pp. 2025!2028. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 12, 2004,
Original Russian Text Copyright + 2004 by Bulatov, A. Rogotnev, V. Rogotnev, Cherepova.
OF FOSSIL FUEL
Development of State Reference Samples of Mercaptan Sulfur
Content in Petroleum Products
A. V. Bulatov, A. S. Rogotnev, V. A. Rogotnev, and A. G. Cherepova
Ekros Research and Production Association, Private Company, St. Petersburg, Russia
Ustinov Baltic State Technical University, St. Petersburg, Russia
Received June 16, 2004
Abstract-State reference samples were developed for determining the content of mercaptan sulfur in
petroleum products, and a method for metrological certification of these samples by the certified meas-
urement procedure was approbated.
One of the major tasks in assessment of the quality
of petroleum products is to determine the content
of the mercaptan sulfur (MS) because mercaptans
cause corrosion and impair the strength of metals and
other materials contacting them under conditions of
production, application, and storage [1, 2].
The MS in petroleum products is mainly deter-
mined by potentiometric titration with an ammonia
solution of silver nitrate, using a silver sulfide indi-
cator electrode .
For metrological provision of procedures used to
determine the MS content in petroleum products by
analytical monitoring laboratories of petrochemical
and oil-refining industry, state reference samples of
MS content in petroleum products (MS SRSs) are
There are no samples of this kind in Russia today.
Such samples, however, are demanded by fuel- and
energy-producing enterprises for internal and external
checkout in the assessment of the quality of petroleum
products. This fact stimulated the development and
production of MS SRS.
The goal of this study was to develop and metro-
logically certify the first batches of MS SRS.
State reference samples SM-0.001-EK, SM-0.003-
EK, SM-0.005-EK, SM-0.01-EK, and SM-0.03-EK
with the rated MS content of 0.001, 0.003, 0.005,
0.010, and 0.030 wt %, respectively, were prepared
by dissolution of an accurately weighed portion of
phenylmethanethiol (Merck, Germany). As matrix
material we used isooctane or decane (Merck, Ger-
An ammonia solution of copper(II) sulfate was
prepared as described in . A 3.9-g portion of cop-
per(II) sulfate hydrate was dissolved in 700 ml of
distilled water in a 1000-ml volumetric flask, a 25%
ammonia solution was added until the precipitate of
the basic copper(II) salt dissolved completely, after
which an additional 50 ml of 25% ammonia was in-
troduced, and the solution was brought to the mark
with distilled water. The concentration of the am-
monia solution of copper(II) sulfate was determined
with a reference solution of sodium thiosulfate, which,
in turn, was standardazied with a Grade 1 SRS of
potassium bichromate (SRS 2215381).
The certification of MS SRSs was performed by
the measurement procedure
(MP) for determining
MS in petroleum products . According to this MP,
a sample of MS SRS was weighed in a weighing bot-
tle and quantitatively transferred into a 100-ml sepa-
ratory funnel, for which purpose the weighing bottle
was washed no less than three times with 233-ml por-
tions of toluene. Then the titrant, ammonia solution of
copper(II) sulfate, was added to the separatory funnel
from a 2-ml Class 2 buret (scale division 0.01 ml) in
the amount of 90% relative to the calculated amount
required for the titration. The mixture was shaken
Improved by the Ekros Research and Production Association;
the procedure is hereinafter designated as EK 03-2003-NP;
certified by the Ural Research Institute of Metrology, Federal
State Unitary Enterprise (Certificate no. 253.12.02.129/2003).