Artículo en PDF
How to cite
Complete issue
More information about this article
Journal's homepage in redalyc.org
Sistema de Información Científica
Red de Revistas Científicas de América Latina y el Caribe, España y Portugal
Rev. Int. Contam.
Ambient.
13
(2), 87-95, 1997
EVALUATION OF COMPOSITlON AND EVAPORATiON BEHAVIOR OF COMMERCIAL THINNER SAMPLES
EXPENDED M MEXICO
m
Joel REZA, Gabriela SALAZAR and Arturo TREJO
Gerencia de Investigación Aplicada de Procesos, Subdirección de Transformación Industrial, Instituto Mexicano del Petróleo, Eje
Central Lázaro Cárdenas
152,07730
D. F., México.
(Recibido marzo
199 7,
aceptado septiembre
1997)
Keywords: thinner, volatile organic compounds, gas chromatography, solvent evaporation rate
ABSTRACT
The chemical composition of 34 thinner samples obtained in the Metropolitan
Area
of Mexico City was
quantified by gas chromatography. Both the total number and the composition of each of the identified
compounds showed great variations from one sample to another. Nonetheless, toluene, n-hexane, acetone
and nietliaiiol were the iiiost frequently and highest concentration conipounds identified in this study. By
using a thermodynaniic model of solvent blend evaporation, which accounts for mixture non-idealities in
tentis ol coinporient activity coefíicients, the evaporation time versus solvent composition (solvent
balance) curves were calculated for 1 O of theanalyzed samples. The calculated evaporatioti rate showed a
broad specúum in their behavior (fast, intermediate and low). Regarding solvait balance, in the 10 samples
considered, tlie low solvency components (diluents) were evaporated disproportionately slow in regard to
latent and high solvency (active) solvents. Tlie high solvency components rapidly became depleted in the
residual solvent. This leads to the undesirable effect known as solvent imbalance. The appreciable differ-
ences observed in the total nuniber of compounds and iii their compositions, along with tlie evaporatioii
behavior of the analyzed samples lead to conclude that apparently no technical, environmental or toxico-
logical criteria were applied to formulate the cornrnercial analyzed samples.
RESUMEN
Se presentan resultados de la composición química, obtenidos por medio de un estudio por cromatografia
de gases, de 34 muestras de adelgazadores comerciales (tíner) obtenidas en diversas zonas geográficas de la
Zona Metropolitana de la Ciudad de México. Tanto la cantidad como la concentración de los compuestos
detectados denotaron una gran variabilidad en las diferentes niuestras estudiadas. Sin embargo, se observó
que el tolueno, el n-hexano, la acetona y el metano1 fueron las sustancias que se presentaron con mayor
frecuencia y en concentraciones mas altas en todas las muestras de tíner. Con base en los valores de la
composición de las muestras de tíner analizadas y empleando un modelo termodinámico, que consideró el
comportamiento no ideal de éstas
en
téminos de coeficientes de actividad, se calculó el comportamiento de
evaporación de algunas de las muestras de tiner estudiadas. En general las muestras consideradas no
presentaron un buen "balance disolvente". Las diferencias tan apreciables observadas tanto
en
el número de
compoiientes como en la composición, así como en el comportamiento de evaporación de las muestras
estudiadas indican que probablemente no se aplican normas ni criterios para definir sus características
técnicas, ambientales o de toxicidad para aplicaciones comerciales e industriales específicas.
INTRODUCI20N
ing on the solvent or solvency capacity towards a given poly-
mer or resin, the components of tlie tlumer are classified in three
A thinner is a cominercial mixture of volatile organic com-
groups: active solvents, cosolvents or latent solvents and
pounds (VOC's) widely used to manufacture and apply many
diluents. The active solvents are those VOC's which have the
products such as paints, lacquers, adhesives, and inks. The thin-
capacity to dissolve apolymer or resin in industrial and commer-
ner is formulated as a mixture from relatively pure solvents and
cial products such as paints, adhesives and inks, and help to
each solvent has a specific function in the formulation. Depend-
define important properties of these products such as viscosity,
J.
Reza
et
al
solids content and evaporation rate. Tlie latent solvent is not a
solvent by itself but enhances tlie solvent capacity of tlie active
solvent witli wliicli it is generally blended. Tlie diluent does not
have any solvent effect but helps to control the costs in the
solvent mixture production. Tlie behavior of a pure VOC as ac-
tive, latent or diluent depends on the polyiner or resin to dis-
solve (Nelson et
al.
1970). So, tlie specific use to wliich it is
given and the final quality expected are factors that determine
the type and concentration of each VOC in a thinner sample.
Therefore, it is not possible to establish a generic thinner for-
mula for a broad spectrum of applications (Walsham and Edwards
197 1). However, some aspects to consider during thinner formu-
lation are: (1) the concentration of VOC's in a thinner sample
must vay according to the values given in table
1,
(2) tlie quality
of a tliinner is related to its diluent concentration as indicated in
table
11
and (3) the content of the latent solvent must be in a 1:3
ratio witli respect to tlie active solvent concentration (Gutiérrez-
Flores 1975).
TABLE
1.
TYPICAL COMPOSITION OF A THINNER
-
Solvent
Composition
(%
volume)
Active
Latent
Diluent
TABLE
11.
THINNER QUALITY AS A FUNCTION OF ITS DILUENT
CONCENTRATION
Thinner guality
Diluent concentration
(%
volume)
H
i g t i
45 10 50
Medium
50 to 55
T
nw
>
55
The commercial thinners sold in Mexico City show great di-
versity in the number and type of VOC's they contain and in
Uieir composition as well (Bmso-Moguel
and
RomereDíaz 1988,
Lorenzana-Jiinénez et
al.
1988). Furthertnore, highly toxic sub-
stances such as toluene, metlianol. n-hexane, acetone, benzene,
and xylenes have been found in relatively high concentrations.
Tliis leads to tlie availability of tliinners of dubious quality froin
a technical point of view and notably Iiarmful from a toxicity
point of view. Thinner cotnponents representan additional health
risk due to tlieir high volatiliiy and persistence in the environ-
ment, their higli capacity to be moved from their source to any
place and to be transformed into other more toxic or dangerous
substances to man and the environment (Bello et
al.
1995).
Solvent inhalation abuse is a growing public healtli problein
in Mexico and in other countries. Thousands of children and
youngsters in Mexico City are deliberately inlialing tliinner va-
pors in order to induce sensations of euplioria and esliilaration.
Altliougli the practice itself is not newv, its occurrence in epi-
deinic proportions through the City have brought the problein
into nation-wide prorninence. According to tlie Mesican Dmg
Addictions National Inquiry, 4.8% of the urban population be-
tween 12 and 65 years old used dmgs at least once during tlieir
life. The organic solvents use was overpassed only by tlie use
of marijuana and tranquilizers. Tnformation supplied by tlie
"Centros de Integración Juvenil" sliowed tliat
56%
of tlie sol-
vent abusers started using organic solvents wlien they were
between 10 and 19 years old (Secretaría de Salud 1990). Acute
intoxication with tliinner aEects tlie central nervous systein dis-
turbing perception and inducing hallucinations, liiglier levels of
esposure induce serious effects to the liver, heart and the visual
system (Press and Done 1967, Guzmán-Flores 1975, Barroso-
Moguel andRomero-Díaz 1988). Due to its cornposition, thinner
also tnust be considered as a highly toxic agent with mutagenic
activity (Gómez-Arroyo and Castillo-Ruiz 1985). Tliese adverse
effects are of considerable importance and consequently an ex-
position of any magnitude to tliese harinful substances repre-
sents an unpredictable healtli risk.
The technical properties of a tliinner sainple sucli as density,
viscosity and volatility, depend on tlie different VOC's present
and tlie tliinner noxious effects are also directly related to tlie
concentration of highly tosic coinponents. Einission of VOC
'S
due to evaporative processes are considered an environmental
problem due to their significance in tlie fonnation of pliotoclienii-
cal oxidants, especially ozone (Andersson-Skold et
al.
1992). It
has been suggested tliat Mesican authorities inust implement
regulations to set teclinical and toxicological criteria of fonnula-
tion in order to generate new tliinner samples suitable for several
industrial and cominercial applications, witli a very low concen-
tration of tosic coinponents and liazardous air pollutants
(Barroso-Moguel and Romero-Díaz 1988, Lorenzana-Jitnénez et
al.
1988). Unfortunately. to our knowledge, there are no regula-
tions establishing tecluiical, environmental and toxicological cri-
teria to formulate tliinners in Mexico.
Since thinners are solvent inixtures in wliich complicated
cheinical interactions and synergistic effects are present it is of
the utmost iinportance to liave a coinplete knowledge of tlieir
different VOC's and their composition in order to liave reliable
information. Hence, considering tlie critica1 iinportance tliat a
cliemical analysis of tliinners samples lias in severa1 fields, in
this work we liave conducted a systematic laboratory study to
determine the composition of several coiniiierciai tl~inner
sainples
distributed in Mexico City witli inultifold objectives:
(
i
)
to ob-
tain conclusions regarding tlie teclinical perforiiunce of tlie ana-
lyzed commercial sainples tluougli tlie calculation of tlie tlunners
evaporation time and tlieir composition during evapomtion, also
known as solvent balance, using a tlierinodynaiiiic iiiodel of sol-
vent blend evaporation and tlirougli a comparison of tlieir com-
position witli recornrnended literature values for tlie coinposi-
tion of active, latent and diluent coniponents; (ii) to generate
data bases on wliich researches from different areas may base
themselves to carry out clinical, plurmacological and toxicologi-
cal studies and establisli tlie neurotoxic properties of tliinners
and their individual components related to tlieir cliemical struc-
ture; (iii) to produce useful iníonnation to create data banks for
the evaluation and distnbution of atmospheric pollutants; (iv) to
liave reliable iníorination to develop a proper legislation to es-
tablish standards on tlie forinulation. production, distribution
COMPOSITION AND EVAPORATION OF COMMERCIAL THINNER SAMPL,ES OF MEXICO CITY
89
and use of solvent mixtures and products containing them.
MATERIALS AND METHODS
Chromatographic analysis of thinner samples
The gas chromatographic analysis of 34 thinner samples was
performed on a Tremetrics model 541 gas chromatograph
equipped with a 2 m x 3
mm
stainless steel column filled with 15%
Carbowax 20M on Chromosorb W-HP 1001 120, flame ionization
detector (FID) and a LabQuestTM
chromatography data system
(version 5.0). The operating conditions were as follows: nitro-
gen as carrier gas at 30 cm3/min., hydrogen supplied to the de-
tector at 30 cm3/min. and airat 350 cm3/min. The column teinpera-
ture was 50 OC, the injector block temperature 190 OC andthe de-
tector block temperature 200 "C. A 0.5 microliter sample was in-
jected.
Standards
Tlie identifícation of the different components of the thinner
samples was made by comparison with the corresponding reten-
tion time of pure reference substances obtained from commercial
sources of the highest purity available, generally greater than
99.9% mol.
The basic steps of tlie method for the thinner analysis include
the transfer, with a volumetric pipet, of a 5 cm3 aliquot from the
cominercial sample, kept in an ice bos, to a clean 5.5 cm3 vial
witiiout headspace and immediately covered. A sample was taken
froni tlie vial with a microsyringe for analysis and injected by
hand into the chromatograph. Four injections were carried out
for each thinner sample and the reported composition results
represent the average.
The retention times for the pure reference substances were
obtained each time after the analysis of about 5 samples of dif-
ferent thinners to ver;@ tlie quality of tlie chromatographic
inetliod.
Five calibration standards containing up to ten reference sub-
stances eacli one, at different known concentratisns, were pre-
pared by weiglit and analyzed in order to veri@ tlie quantitative
reliability of tlie inetliod. A total nuinber of 18 different com-
pounds were used to prepare tlie calibration standards.
Suinmarizing, tlie quality of the results was evaluated using
tlie information from fíve repeated runs to obtain retention times
for 30 reference substances, which gave about 300 experimental
retention time points, and from the comparison between tlie
known and cliromatographically derived composition of the five
calibration standards mentioned above, whicli in turn gave about
100 concentration points. Thus, the reported results for tlie coin-
position of the thinner samples analyzed in this work had an
accuracy and precision of 3
%.
Dul~licates
Duplicateanaiysis were perfonned for several thinner samples.
The number of analytical duplicates was 20 %of the total num-
ber of tiiinner saiiiples analyzed by tiie same procedure described.
The relative percent differences between the first analysis and
the duplicates were al1 within the accuracy given above.
Calculation of solvent evaporation
Evaporation time and solvent balance are important proper-
ties of solvent blends used in coating systems. A mathematical
model of solvent blend evaporation for film which accounts for
misture non ideaiities in terms of component activity coeficients
was used in this work to calculate the evaporation behavior of
some of the analyzed thinner samples, at 25 'C.
The total evaporation rate,
Rm,
for a mixture of n components
was calculated as (Sletmoe 1970, Walsham and Edwards 1971,
Yoshida 1972):
where
5
is the activity of component i,
is the rate of evapo-
ration of pure i, C, is the concentration by weight of i, and
y,
is
the activity coefficient of component i.
The method chosen in this work for calculating activity coef-
ficients of the multicomponent misture constituents studied was
similar to the one described by Walsham and Edwards (1971).
This method allows the prediction of component active
coeffcients in binary mixtures by interpolation from the values of
activity coefficients at inñnitedilution, Y
,
,
Y,:
,
ofcomponenis
1 in 2 and 2 in 1, respectively. C om ponent activity coeficients at
any mixture composition were calculated by interpolation from a
matrix ofbinary system infinite dilution activity coefficients. The
composition of each component in the evaporated sample was
obtained with thefollowing expression (Sletinoe 1970):
where V, represents tlie composition of component i in the va-
por. Tlie cliange in compositioii caused by the evaporation of a
sinall liquid fraction was detennined by an equilibrium mass bal-
ance.
A plot of weight of solvent evaporated against time is typi-
cally nonlinear for multicomponent systems. However, tlie rate
of evaporation can be considered constant during the time t
required for evaporation of a small increinental weight
wt
of a
mixture, as given by equation 4. The time t can be as small as
desired by entering the number into the computer program. In
this work, t was físed at 5 seconds.
In a new liquid composition, a new set of activity coeficients
was calculated and the evaporation rate was determined. In this
way, a curve of evaporation rate versus time was calculated and
the composition of the remaining liquid was also followed dur-
ing the evaporation process.
Chromatographic analysis of thinner samples
The chromatographic analysis of tlie 34 commercial thinner
samples studied showed a number of components between 8
and 30. However, it is important to point out that many of the
identified compounds were in low concentration
(<
1
wt
%)
and
were regarded as impurities.
Table
111
shows the mean composition of the main compo-
nents identified in the 34 analyzed samples, whereas the nine
components more frequently found are shown in tlie table
N.
It
may also be observed that al1 the samples contained compounds
in relatively small concentration wliich were not identified.
Toluene was found in each one of the 34 analyzed samples. It
was the most abundant compound, reaching concentrations up
to 87.5
wt
%.
Acetone was the second component in frequency
as it was identified in 76
%
of the samples anaiyzed with concen-
trations up to 3 1.5
wt%.
n-Hexane was the third most frequent
component with concentrations up to 13
wt
%.
Methanol, me-
thyl butyl ketone and benzene were identified in 62
%
of the
samples anaiyzed, however, it is important to remark tliat, wliile
benzene and methyl butyl ketone have concentrations lower than
10
wt
'YO,
methanol can reach concentrations up to 4 1
wt
%.
2-
Propanol, xylene and 3-methyl pentane had similar composition
values; these compounds were present in 59
%
of the samples
analyzed. The rest ofthe identified compounds listed in table
111
had a frequency lower than 50
%.
The fact that toluene was present in high concentrations in ail
tlie samples studied, according to the studies of Lorenzana-
TABLE
111.
AVERAGE COMPOSITION OF THE MAlN COMPONENTS
IDENTIFlED IN 34 COMMERCIAL THlNNER SAMPLES
OBTAINED 1N THE METROPOL.ITAN AREA OF MEXI-
CO ClTY
Component
Average iomposition
(wt%)
Toluene
59.9
Hexane
8.2
Acet one
5.2
Methanol
4.8
Xylene
4.1
Arornatics
(2
C,)
3.0
Propyl acetate
2.8
Cellosolve
2.0
Methyl isobutyl ketone
1.8
2-Propano1
1.7
Butyl cellosolve
1.6
Methyl butyl ketone
1.6
Butyl acetate
1.1
Benzene
0.3
Not identified
1.9
TABLE
IV.
FREQUENCY AND COMPOSITlON RANGE OF SOME
VOC's IDENTIFIED 1N 34 COMMERCIAL THINNER
SAMPLES OBTAINED IN THE METROPOLITAN AREA
OF MEXICO ClTY
Component
Frequency
Composition range
("/.)
(M"/.)
ToIuene
1 O 0
0.06-87.47
Acetone
76
O
-31.46
Hexane
65
O
-13.07
Methanol
62
O
-40.93
Methyl butyl ketone
62
O
-
9.72
Benzene
62
O
-2.21
2-Propano1
59
O
-39.06
Xylene
59
O
-18.69
3-Methyl pentane
59
O
-
9.42
Not identified
1 O 0
O. 1 0 - 2 9 . 6 3
Jiménez
et al.
(1988), suggests that it may be responsible to a
great estent for the psycliic stimulation wlien tliinner is inten-
tionally inlialed. Toluene is a very toxic substance (Hayden
etal.
1977). It has proven to be an inducer of cluomosoinal aiterations
(Gómez-Arroyo
et al.
1986). The nervous system is particularly
vulnerable to this substance due to its liigli lipid solubility
(Devatliasan
et 01.
1984). Carlsson and Linquist (1977) showed
toluene concentration in fatty tissue to be 80 times higher than
in blood. Acute toxicity by toluene inlialation inay result in deatli
due to cerebral edema, pulmonary edema or myocardial involve-
ment (Devathasan
et al.
1984).
Tohene impairs cenkal nervous system (CNS), thus the dys-
function of tlie CNS due to the inlialation of toluene could be
considered to appear as disturbed equilibrium due to tlie iinpair-
ment of the vermis, disturbed skillfulness of tlie extremities due
to the impaiment of the cerebellar liemisplieres and mental retar-
dation due to diíhse cerebral atropliy. Cerebral and cerebellar
atropliy have been well documented (Grabski 196 1, Malm and
Tunell 1980, King
et al.
198 1); visual dysfunction lias aiso been
reported (Takeuchi
el al.
198
la). Toluene has also been iinpli-
cated as a causative agent in cardiac arrhytmias (Taylor and
Hanis 1970).
It has been determined that a glue-soaked cloth in a paper bag
may create a toluene concentration of 200 ppm up to 50 fold
higher than tlie TWA (the time-weiglited average concentration
for normal 8-hour workday anda 40-liour workweek, to wliicli
nearly al1 workers may be repeatedly exposed, day after day,
without adverse effect). Toluene has a TWA value of 50 ppm
(ACGIH 1994).
May be n-Hexane is the most liighly toxic member of the al-
kane series of homologues because, as most organic solvents, it
is highly lipopliilic, lience it is actively absorbed by tlie mamrna-
lian system and accumulated in body tissues, proportionally in
the lipid content; it is an anesthetic that, when ingested, causes
nausea, vertigo, broncliial and general intestinal irritation and
central nervous system effects (Sandmeyer 1981a).
Per se
n-
Heme
is considered to liave no particular neurotosicity, but it is
metabolized
ir? vivo
into neurotosic substances (Spencer
et al.
1978; Coun
et al.
1978). It has been reported tliat tlie neurotoxic-
ity of n-liexane may be easily modified by otlier solvents for
COMPOSlTlON AND EVAPORATION OF COMMERClAL THlNNER SAMPLES OF MEXlCO ClTY
91
example, methyl ethyl ketone (Altenkirch
et
al.
1978; Takeuchi
et
al.
1981b).
Acetone has been considered to be one of the least toxic
solvents used in the industry. However, exposure to high con-
centrations can produce central nervous system depression and
narcosis; prolonged or repeated skin contact may damage the
skin and produce dermatitis (Krasavage
et
al.
198 1).
Methanol toxicity is low as measured by lethality but suble-
thal doses can cause serious effects to the central nervous sys-
tem, the liver and particularly to the visual system. Methanol is
mildly irritating upon direct contact with the eyes and upon pro-
longed contact with the skin. Ingestion has caused serious ill-
ness and deaths (Rowe and McCollister 1982).
As shown in
tables 111
and
IV,
benzene was also found in
some of the analyzed samples. The concentrations detected were
low, Iiowever its presence in the commercial tliinners is worry-
ing, since benzene is a very hanntül substance. Soine cases
have been reporied involving death from acute benzene poison-
ing by deliberate inhalation (Winek
et
al.
1967; Winek and Collom
197 1). Benzene is a lipid soluble coinpound that when inhaled in
liigli concentrations, accumulates in the brain and body fat and
acts as a Spical narcotic poison (Winek and Collom 197 1). Tlie
main effects in benzene intoxication appears to be CNS lesions,
impairment of liearing, dermal and cardiac sensitization, dysp-
nea and tachycardia; benzene decreases arteria1 pressure and is
considered a "suspect carcinogen" (Greenburg
et
al.
1939,
Sandmeyer 1981 b). Benzene also depresses bone marrow and is
therefore a potential source of anemia and otlier blood abnor-
malities (Glaser and Massengale 1962).
It is imporiant to consider that, although present in lower
concentrations, other components such as xylene, 2-propano1
and methyl butyl ketone can cause additional toxic effects in the
solvent blend. Also, toxic effects that results of the feasible
synergetic interaction between the different component in tlie
solvent blend sliould be considered during voluntary and
inadvertant solvent exposure.
Additionally, fiom an environmenial point of
view
once in tlie
atmospliere, the different VOC's which constitute the thinners
representan additional liealth risk due to their high volatility and
persistence in tlie environment, their high capacity to be moved
and their capacity or pliotoreactivity to be transformed into more
toxic and dangerous substances to humans and other living or-
ganisms (Bello
et
al.
1995).
Calculation of solvent evaporation
In order to ver@ the reliability of the calculation metliod used
in this work to estimate the evaporation behavior of solvent
blends, the global evaporation as a function of time, was calcu-
lated for four mixiures siudied experimenially and reporied in the
litérature (Walsharn and Edwards 197 1). The comparison between
the experimental and calculated evaporation rate for the four
mixtures, throughout the composition range between O and 90
wt
%,
shows a mean difference of 2.3 min. (standard deviation
5.4 min.), which we consider to be highly accepiable.
Once the reliability of the calculation metliod to estimate the
evaporation rate of solvent blends was determined, the evapora-
tion rate for 10 out of the 34 analyzed thinner samples was calcu-
lated. Tlie selected thinner samples were those with high con-
centration of Iiiglily toxic substances such as toluene, hexane,
methanol, methyl isobutyl ketone and xylene. In order to sim-
plif) tlie calculations, the original components found in the chro-
matograpliic analysis with low concentration were added to tlie
higher concentration value of those components with similar
chemical stmcture. The rounded up composition of each of the
10 samples is sho~n
in
table V.
Also in
table V
tlie different components of tlie thinners
were classifíed as active, latent and diluent solvents following
the considerations given by Gutiérrez-Flores (1975) to classif)
the components of industrial solvents used in tlie lacquer, paint
and ink industries. Thus,
table VI
gives a summary of the total
composition of active, latent and diluent solvents contained in
each one of the 10 samples, as well as tlie ratios of latent to
active solvents and active to diluent solvents.
It is iinporiant to point out tliat none of tlie tliinners pre-
sented in
tables V
and
VI
fulfíll the forinulation criteria for a
typical thinner shown in
table
1.
Also, taiung the high concentra-
tion of diluent into account, tliat was always greater than 50
wt
%,
and the criteria of
table 11,
it can be concluded that the 10
thinner samples analyzed have low quality. A similar behavior
was observed for tlie otlier 24 studied samples.
The global evaporation rate, as a function of time, estimated
for tlie 10 indicated samples, is presented in
table VII,
from 5 up
TABLE V. ROUNDED COMPOSITlON
(M%)
OF 10 COMMERClAL THlNNER SAMPLES OBTAINED IN THE METROPOLITAN AREA OF
MEXICO CITY
Thinner
Solvent
1
2
3
J
5
6
7
8
9
1 O
AcetoneA
10.41
31.49
7.57
Methyl isobutyl
6.23
7.10
5.96
7.24
ketoneA
Propyl acetateA
5.94
8.88
Butyl acetateA
5.34
5.52
8.51
MethanolL
20.02
9.47
41.56
17.09
19.52
13.40
8.16
2-PropanolL
13.46
12.97
14.54
13.89
7.94
13.74
HexaneD
4.63
3.29
15.45
TolueneD
37.38
65.22
69.97
35.42
63.98
58.70
77.18
73.14
84.44
69.22
XyleneD
15.39
3.59
7.05
AActive solvent, LLatente solvent, DDiluent
J.
Reza el al.
to 90
wt%
evaporated, and are shown in
figure
1.
It can be
Evaporated
(w%)
-
observed that tlie samples present a wide spectrum of evapora-
,o
,
tion rates. The samples 2, 4, 5 and 6 evaporate relatively fast,
while samples 9 and 7 sliow the lowest evaporation rates, re-
70
L
maining sainples have middle evaporation rates.
60
-
50
TABLE VI. ACTIVE, LATENT AND DILUENT SOLVENT CON-
40
CENTRATION (~1%) OF 10 COMMERCIAL THINNER
30
-
SAMPLES OBTAINED 1N THE METROPOLlTAN AREA
20
OF MEXICO ClTY
1 o
INtial concentration
0
1--
-- -
L-pL
LL~LiP
LIpl-d
of solvent
(wt O/O)
I~tial
ratio
O
30
60
90
120
150
180
210
240
270
Mixture Active
Latent
Latent:Active
Active:Diluent
solvent solvent
Düuent
Time
(S)
1
22.58
20.02
57.40
1:1.12
1: 2.54
Fig. 1. Global evaporation rate as a function of time for 10 niixtiires of
2
31.49
O
68.51
1: 2.18
commercial thinner samples obtained in the Metropolitan Area of
3
7.10
22.93
69.97
1:0.30
1: 9.85
Mexico City
4
7.57
41.56
50.87
1 :O . 1 8
1: 6.72
5
5.96
30.06
63.98
1 : 0 . 2 0
1:10.73
tlie remaining liquid is diluent. Sample 9 was also only formu-
6
7.24
34.06
58.70
1 : 0 . 2 1
1: 8.11
7
5.34
13.89
80.77
1:0.38
1:15.13
lated with active solvents and diluent. Tlie initial diluent con-
8
5.52
21.34
73.14
1 : 0 .2 6
1:13.25
centration in this tlunner sample is too lugli, during the evapora-
9
8.51
o
9 1.49
1:10.75
tion course this concentration increases and at tlie end of tlie
The values calculated for the change of composition of the
active, latent and diluent solvents in the remaining liquid (sol-
vent balance) during the evaporation process of the 10 tliinner
samples, are included in
table VI11
and in
figure
2, from wluch
the following remarks can be derived:
With exception of the behavior observed for samples 4 and 9,
in tlie other eight cases the concentration of diluent on the re-
maining liquid always increases during tiie evaporation. In sample
1 tlie concentration of the active solvent is almost constant
throughout the evaporation, decreasing a little at tlie end of tlie
evaporation, the diluent concentration increases appreciably
while tliat for tlie latent solvent diminishes until it mns out.
A
evaporation the diluent concentration in tlie reinaining liquid is
still of 78
wt
%.
It is evident tliat the solvent balance of tliis
sample is por.
Sample 4 presents a solvent balance tliat differs witli the other
samples because its diluent concentration diminislies from 5 1
wt
%
at beginning of evaporation to 34.7
wt
%
when tlie total
:ample evaporated is 90
wt%;
the latent solvent concentration
increases from 4 1.5 to 62.1
%;
however, the active solvent con-
centration diminishes in a such manner tliat, at end of evapora-
tion, its concentration is hardly of 3.2
wt9'0.
Therefore, this sainple
does not exhibit a good solvent balance as well.
The estimated balance solvent during evaporation shows tiiat
for the 10 samples considered the low solvency components
evaporate disproportionately slow in regard to the active and
TABLE VII. EVAPORATION RATE AS A FUNCTION OF TIME FOR 10 COMMERCIAL THINNER
SAMPLES OBTAINED 1N THE METROPOLlTAN AREA OF MEXICO CITY
wtO/o evaporated
Thinner
5
10
20
30
50
60
70
75
80
85
90
time
(S)
similar beliavior is observed for rnixtures 3,5,7,8 and 10.
latent solvents, in such a manner that the liigh solvency coinpo-
Sample 2 was formulated only with active solvents and
nents will rapidly become depleted in the residual solvent during
diluents. During the evaporation process, tlie concentration of
evaporation. This leads to the undesirable effect of solvent im-
the diluent increases at tlie expense of the active solvent con-
balance. Generally, if tlie mixture was formulated to be out of
centration. When 70% of the sample is evaporated, 90
wt
%
of
solvent balance from the beginning, tlie solvent imbalance will
COMPOSITION AND EVAPORATION OF COMMERCIAL THINNER SAMPLES OF MEXICO CITY
Plg. 2. Solvent composition during evaporation of 10 thinner samples obtained in the Metropolitan Area of Mexico City.
V:
Active
solvent, A: Latent solvent,
i
:
Diluent
TABLE VIII. EVAPORATION BEHAVIOUR FOR 10 COMMERCIAL
THINNER SAMPLES OBTAINED IN THE METRO-
POLITAN AREA OF MESICO ClTY
wt% evaporated
Thinner
solvent
O
30
60
90
wtO/o remaining Liquid
1
Active
22.58
22.35
21.17
17.83
Latent
20.02
14.60
5.12
0.18
Diluent
57.40
63.05
73.71
81.99
2
Active
31.49
23.94
18.63
5.89
1.atent
Diluent
68.51
76.06
88.37
91.11
3
Active
7.10
8.32
10.33
11.08
Latent
22.93
17.17
6.12
1.42
Diluent
69.97
74.51
83.54
87.50
4
Active
7.57
6.91
4.65
3.19
Latent
41.51
47.41
56.07
62.07
Diluent
50.87
45.69
39.28
34.74
5
Active
5.96
7.05
9.13
10.60
Latent
30.06
26.28
17.89
10.85
Diluent
63.98
66.67
73.07
78.55
6
Active
7.24
8.54
11.05
20.54
Latent
34.06
3 1.98
27.45
4.93
Diluent
58.70
59.48
61.60
74.53
7
Active
5.38
6.70
8.82
10.07
Latent
13.85
6.69
0.15
O
Diluent
80.77
86.81
91.03
89.93
8
Active
5.52
7.04
9.93
11.61
Latent
21.34
13.71
2.60
0.12
Diluent
73.13
79.25
87.47
88.27
9
Active
8.50
9.99
12.77
22.03
Latent
Diluent
91.50
90.01
87.23
77.97
10
Active
8.88
9.88
11.29
12.38
Latent
21.90
15.99
6.13
1.98
-
Diluent
69.21
74.13
82.58
85.64
most likely grow worse during evaporation. In general it can be
observed that the 10 samples evaluated do not exhibit a good
solvent balance, so they are deficient from a technical point of
view and hence are inappropriate to be used in many domestics
and industrial applications.
CONCLUSIONS
The 34 cominercial thinner samples analyzed showed great
variability botli in nurnber and in the concentration range of their
constituents. Toluene, acetone, hexane, methanol, xylene, 2-pro-
panol, methyl butyl ketone, benzene and 3-methyl pentrne were
the more frequently identified coinpounds.
By using a therinodynamic model, the evaporation beliavior
for 10 of the 34 analyzed samples was coinputed. The calculated
evaporation rates exhibited a broad range in evaporation time.
Regarding tlie solvent balance, it was observed tliat the samples
studied were formulated witli too low concentration of liigli sol-
vency components and too high concentration of low solvency
components.
Based on tlie appreciable differences in tlie nuinber of com-
ponents, their concentrations, evaporation and solvent balance
beliavior of the actual commercial thinner samples, besides from
the toxicity of the compounds, it may be concluded that a criteria
to detemune the composition characteristics during thinner for-
mulation does not exist and tliat, in order to obtain superior
solvent blend formulations frorn technical, environinental and
toxicological points of view further research must be done.
It is highly recomrnendable that Mexican authorities set regu-
lations to define thinner fonnulation criteria in order to develop
and produce improved solvent blends with adequate solvency
and evaporation properties according to specific applications,
including a decrease in the concentration of highly tosic sub-
stances, in order to reduce their noxious effects to solvent sniff-
ers, workers and the environment.
ACGIH (1 994).
Threshold linrit i7aluesfor cher?rical substances
and physical agel?ts and biological exposure indices.
American Conference of Govermnental Industrial Hygienists.
OH, 124p.
Altenkirch H., Stoltenburg G. and Wagner H. M. (1978).
Experimental studies on hydrocarbon neuropatliies induced
by rnethylethyl-ketone. J. Neurol. 219, 159- 170.
Andersson-Skold Y., Grennfelt P. and Pleijel K. (1 992). Plioto-
chemical ozone creqtion potentials: a study of different con-
cepts. J. Air Waste Manage. Assoc. 42, 1152-1 158.
ASTM (1987). Standard test inethods for evaporation rates of
volatile liquids by Shell tliin-filiii evaporoineter. Designation
D3539-87, pp. 55 1-556.
Barroso-Moguel R. and Romero-Díaz V. (1 988).
Thir?ner:
inhala-
ción y consecuencias.
Instituto Nacional de Neurología y
Neurocimgía. México, 128 p.
Bello L., Rosal R., Sastre H. and Diez F. (1 995). Los VOC y el
medio ambiente. Ing. Quím. (inayo), 18 1-187.
Carlsson A. and Lindquist T. (1 977). Esposure of aniinals and
mento toluene. Scand. J. Work Environ. Healtli 3, 135-143.
Couri D., Abdel-Raliain M. S. and Hetland L. B. (1978).
Biotransformation of n-liesane and metliy
l
n-butyl ketone in
guinea pigand inice. Ain. Ind. Hyg. Assoc. J. 39,295-300.
Devathasan G., Low D., Teoli P. C.
. Wan S. H. and Wong P. K.
(1984). Complications of chronic glue (toluene) abuse in
adolescents. Aust. N. Z. J. Med. 14,39-49.
Glaser H. H. and Massengale O. N. (1962). Glue-snifing in
children. Deliberate inhalation of vaporized plastics ceiiients.
J. Am. Med. Assoc. 181,301-303.
Gómez-Arroyo S. and Castillo-Ruíz P.
(
1985). Sister cliromatid
exclianges induced by tliinner in
Jkia faba.
Contain. Ainb. l.
17-23.
Gómez-Arroyo S., Castillo-Ruíz P. and V-lalobos-Pietrini R. (1 986).
Cliroinosoinal alterations induced in
Mcia fabn
by differerit
industrial solvents: thinner, toluene. benzene. n-liesaneo n-
Iieptane, and etl~yl
acetate. Cytologia 51, 133-142.
Grabski D. A. (1961). Toluene sniffing producing cerebellar
degeneration.
Am.
J. Psycliiatry 118,401-462.
COMPOSlTlON AND EVAPORATION OF COhfMERCIAL THINNER SAMPLES OF MEXICO CITY
9.5
Greenburg L., Mayers M. R, Goldwater L. and Smiúi A. R. (1939).
Benzene (benzol) poisoning in the rotogravure printing
indusíry in New York City. J. Ind. Hyg. Tosicol. 21,395-420.
Gutiérrez-Flores R. (1 975). Solventes Industriales. Cuadernos
Científicos CEMEF 2,3548.
Guzmán-Flores C. (1 975). Neurobiología del tíner. Alteraciones
conductuales producidas a largo plazo. Cuadernos Científi-
CQS
CEMEF 2,49-58.
Hayden J. W., Peterson R G. andBnickner J. V. (1977). Toxicology
of toluene (methylbenzene): Review ofcurrent literature. Clin.
Toxicol. 11,549-559.
King M. D., Oliver J. S., Lush M. and Watson J. M. (1 98 1). Solvent
encephalopatliy. Br. Med. J. 283,663665.
Krasavage W., O'Donoghue J. and Divicenzo G. (1981). Ketones.
In:
Patly
S
industrial hygiene and toxicology
(Clayton G.
and Clayton F., Eds.). Wiley, New York, Vol. 11 C, pp. 4709-
1800.
Lorenzana-Jiménez M., Capella S., Labastida C., Magos G. A.
and Anuncio-Cliassin 0 . (1 988). Detenninacióii de la coinpo-
sición de varias muestras de tíner por cromatografía en fase
vapor. Contam. Ambient. 4,65-7 1.
Malm G. and Tunell U. L. (1980). Cerebellardysfunction related
to toluene snifing. Acta Neurol. Scand. 62,188- 190.
Nelson R., Figurelli V,Walsham J. and Edwards G. D. (1970).
Solution tlieory and tlie computer- effective tools for tlie
coatings cliernist. J. Paint Teclinol. 47,64465 1.
Press E. and Done A. K. (1967). Solvent snifing. Physiologic
effects and corntnunity control ineasures for intoxication froin
tlie intentional in1,ialation of orgariic solvents. 1,II. Pediatrics
39, 45 1361,611622.
Rowe V. K. and McCollistei S. B. (1982). Alcohols. In:
Patly's
it7h1strial hsgiene and toxicology
(Clayton G. and Clayton
F. Eds). Wiley, New York, Vol. IIC, pp. 4527-4708.
Sandmeyer E. E. (1981a). Aliphatic hydrocarbons. In:
Patty's
industrial hygiene and toxicology
(Clayton G. and Clayton
F.,
Eds).
Wiley, New York, Vol. IIB, pp. 3 175-3220.
Sandmeyer E. E.
(
198
lb). Aromatic hydrocarbons. In
Patly
'S
industrial hygiene and toxicology
(Clayton G. and Clayton
F., Eds). Wiley, New York, Vol. IIB, pp. 3253-343 1.
Secretaría de Salud. (1990).
Encuesta Nacional de Adicciones.
Sisten~a Nacional de Encuestas de Salud.
Secretaría de Sa-
lud. México, D. F., 494 p.
Sletmoe G. (1970). The calculation of mixed hydrocarbon-
o\ygenated solvent evaporation. J. Paint Technol. 42,246-259.
Spencer P. S., Bishoff M. C. and Schaumburg H. H. (1978). On the
specifíc molecular configuration of neurotoxic aliphatic
hexacarbon compounds causing central-peripheral dista1
axonopathy. Toxicol. Appl. Phmcol. 44, 17-28.
Takeuclu. Y., Hisanaga N,, Ono Y., Ogawa T., Hamaguchi Y. and
Okainoto S. (1 98 la). Cerebellar dysfunction caused by snifhg
of toluene-containing tiiimer. Ind. Healtli 19, 163-169.
Takeuclu. Y., Ono Y. and Hisanaga N. (1981b). Anexpenniental
study on the combined effects of n-hexane and toluene on
theperipheral nerve ofthe rat. Brit. J. Ind. Med. 38, 14-19.
Taylor G. J. and Harris W. S.
(
1970). Glue snifing causes heart
block in mice. Science 170,866-868.
Walsliain J. and Edwards G. (1 97 1).
A
model of evaporation froin
solvent blends. J. Paint Technol. 43,64-70.
Winek C. L., Collom W. D. and Wecht C. H. (1967). Fatalbenzene
exposure by glue-sniíling. Lancet 1,683.
Winek C. L. and Collom W. D. (1971). Benzene and toluene
fatalities. J. Occup. Med. 13,259-261.
Yosliida T.
(
1972). Solvent evaporation from paint fílms. Progr.
Org. Coatings 1,73-90.
logo_pie_uaemex.mx