MCU14/0056 Response to SARA - Consulting Report

EN 858-1:2002 (E)

If the samples have to be transported to an external laboratory, they shall be weighed into glass bottles. The
samples shall be preserved within 15 min by addition of acid as described above. They shall either be further
preserved by addition of 1.1.2-trochioro-1.2.2-trifluoroethane as above before transport, or they shall be sent to the
analysis laboratory at 4°C. If preserved by solvent, at the analysis laboratory the samples shall be transferred to
separating funnels for extraction as above. If the samples have been refrigerated then the solvent should be added
to the sample bottle, then transferred to separating funnels for extraction as above.

After phase separation the organic function is run off and immediately filtered through approximately 10 g of
anhydrous sodium sulphate (Na2SO,) into a volumetric flask with a rated volume of 50 ml.'The extract is made up
to the mark with the solvent, washed through the sodium sulphate so as to include any hydrocarbons remaining in
the sodium sulphate. ,

A.2.2 Evaluation

Measurement is made against a reference of the pure solvent of same layer thickness using matched cuvettes of
equal length. Before measurement, a transmission value of exactly 100 % shall be set with the cuvettes inserted, at
3.2 um. Those absorption bands showing 3,38 ym and 3,42 pm shall be recorded.

The mass concentration of the hydrocarbons in the water sample is obtained from:

L4: Vo (Ei/ CG + Eo/ C2)
Ved

G=
(A.1)
where
G_ is the mass concentration of the hydrocarbons in the water sample, in mg/l;
Vre is the volume of the extracting agent used for extraction, in ml;
E, is the spectral absorption magnitude of CH, band at 3,38 pm;
C, is the molecular extinction coefficient of the CH; band (8,3 ml/mg-cm);
&, is the spectral absorption magnitude of CH, band at 3,42 um;
C, is the molecular extinction coefficient of the CH, band (5,4 mi/(mg-em);
Vp_ is the volume of water sample used, in |;
dis the layer thickness of absorbent solution, in cm.
The result is indicated as a rounded value to an accuracy of:
0,1 mg/l for < 10 mg/l and
1mg/ for 10 mg/l.

Fuel oil ISO-F-DMA in accordance with 8.3.3.1.2 shall be used as the reference liquid for calibration, i.e. to
determine the group absorbance coefficients.

It is possible to use “fixed wavelength" infrared devices when the hydrocarbon concentrations are more than
5,0 mg/l. With this method the hydrocarbon concentration is evaluated solely using the CH, absorption band at
3,42 ym. The fuel oil in accordance with 8.3.3.1.2 shall also be used for calibration. Extraction and preparation of .
the extract shall be as described in A.2.1.

36 This is a licensed reproduction produced by SAI Global Ltd, an authorized distributor of British Standards