Analytical Chemistry

aromatic petroleum distillate 38%

butyl cellosolve 10%

water 30%

mineral lubricating oil 13%

oleic acid 8%

ammonia 0.5%

dyestuff <0.5%

Table 12.2 Analytical scheme for a carburettor and combustion chamber cleaner

Step or determination Comments Conclusion or result

(1) Karl-Fischer titration for total H 2 O in
original sample

amperometric end point 30% w/w H 2 O

titration of excess acid after

absorbing NH 3 in standard acid

solution

0.5% w/w NH 3

0.4% w/w N 2

(4) original sample extracted with a
saturated NaCl solution in a calibrated
vessel

removes H 2 O quantitatively 30% w/w H 2 O

(5) infrared spectrum of organic phase from
4 recorded

showed presence of aromatic material, a

carboxylic acid salt and butyl cellosolve

(6) hydroxyl number for organic phase
from 4

acetylation reaction 10% w/w butyl cellosolve

(7) acid number for organic phase from 4 potentiometric titration with
alcoholic KOH

~0.5% w/w free acid

(8) organic phase from 4 extracted with
HCl and infrared spectrum or organic
residue recorded

removes butyl cellosolve showed presence of aromatic material and

a carboxylic acid

(9) aqueous phase from 4 evaporated to
dryness and infrared spectrum of residue
recorded

no water-soluble organic material detected

(10) original sample evaporated on steam-
bath under N 2 and infrared spectrum of
residue recorded

viscous liquid residue, orange

brown colour

probably contains a dye, spectrum similar

to that of oleic acid

(11) acid number for residue from 10 see 7 7.5% w/w oleic acid

(12) residue from 10 chromatographed on
silica column

separated into two fractions

(13) solvent removed from fractions eluted
in 12 and infrared spectra of residues
recorded

1st fraction almost colourless

residue 2nd fraction orange

residue

spectrum typical of a mineral lubricating

oil spectrum identical to that of oleic acid

(dyestuff <0.5%)