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TECNOCIENCIA CHIHUAHUA, Vol. XV (1) e 761 (2021)
https://vocero.uach.mx/index.php/tecnociencia
ISSN-e: 2683-3360
Artículo de Revisión
Methanol Detection in Commercial Sanitizing Gels,
During the COVID-19 Pandemic
Detección de metanol en geles desinfectantes comerciales, durante la
pandemia COVID-19
*Correspondencia: francisco.paraguay@cimav.edu.mx (Francisco Paraguay-Delgado)
DOI: https://doi.org/10.54167/tecnociencia.v15i1.761
Recibido: 11 de febrero de 2021; Aceptado: 10 de mayo de 2021
Publicado por la Universidad Autónoma de Chihuahua, a través de la Dirección de Investigación y Posgrado.
Abstract
Some antibacterial gels, used for commercial sanitizing, containing ethanol (active) and methanol
(toxic) were quantified. The health emergency caused by the COVID-19 epidemic has motivated the
production of sanitizing gels to cover higher demand. The analytical composition of 24 commercial
gels is reported (15 produced by national and transnational companies, and nine collected from
public areas – in use). The chemical analysis results found that only one brand of 15 gels meets the
quality requirements regarding 70% (wt./wt.) of ethanol content. Concerning the collected gels,
none of them contains the minimum active compound required. The non-compliance of this
requirement means that these gels present their sanitizing action diminished. A striking result is
that 25% of commercially packaged gels contain methanol - a toxic substance - in alarming
amounts, hundreds of times more than the FDA upper limits requirement.
Keywords: methanol; ethanol; sanitizer gels; sars Cov-2; Covid-19.
Resumen
El contenido de sustancias etanol (activo) y metanol (tóxico) se cuantificó para geles desinfectantes
comerciales. La emergencia sanitaria provocada por la epidemia de COVID-19 ha motivado la
producción de geles desinfectantes para cubrir la mayor demanda. Se reporta la composición
analítica de 24 geles comerciales (15 producidos por empresas nacionales y transnacionales,
también nueve geles recolectados que estuvieron en uso desde áreas públicas). De los resultados del
análisis químico, se encontró que solo una marca de 15 geles cumple con los requisitos de calidad
con respecto al 70% (peso/peso) del contenido de etanol. En cuanto a los geles recolectados de zonas
públicas, ninguno de ellos contiene el compuesto activo mínimo requerido. El incumplimiento de
este requisito hace que estos geles presenten disminuida su acción sanitizante. Un resultado
Luis de la Torre-Sáenz, Daniel Lardizábal-Gutiérrez, Ivanovich Estrada-Guel,
Francisco Paraguay-Delgado*
Centro de Investigación en Materiales Avanzados SC (CIMAV), Av. Miguel de Cervantes 120.
Complejo Industrial Chihuahua. Chihuahua, Chihuahua, México. C.P. 31136.
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TECNOCIENCIA CHIHUAHUA, Vol. XV (1) e 761 (2021)
sorprendente es que el 25% de los geles empacados comercialmente contienen metanol, una
sustancia tóxica, en cantidades alarmantes, cientos de veces más que los límites superiores
regulados por la FDA.
Palabras Clave: metanol; etanol; geles sanitizantes; sars Cov-2; Covid-19.
1. Introduction
The ethanol-based sanitizing gels production increased markedly in 2020, mainly caused by the
recent COVID-19 pandemic (March 2020). The purpose of its disinfecting action makes this product
available in almost all public facilities, such as banks, supermarkets, hospitals, offices, etc. The
advantage of this product is its use in some places where there is no access to soap and water, and
its sale doesn’t require a prescription (Paulson, 1999). Before the present pandemic, this product
was in low demand. However, as it became a product promoted by health institutions as a
preventive product (Alvarez, 2020), with high antimicrobial efficiency, the people increased its
usage considerably, which is why many companies began their mass production. Even part of the
people made their formulations based on videos and online tutorials on the websites. This activity
generated a problem since there is no precise regulation of established requirements. The
production is currently carried out with various chemical compounds, but several of them could be
toxic. Some formulations could harm users, starting from a simple dryness or skin irritation, even
severe poisoning. Antibacterial gels are defined as liquid disinfectants for applications on hands
and surfaces. Its main component must be 60-80% (wt./wt.) Isopropyl alcohol or 70% ethanol. The
last one is the most commercially used, due mainly to the fact that being cheaper than Isopropyl
alcohol. The 70% ratio is cited by several studies, such as those carried out by Guilhermetti et al.
(2010), where they used 12 alcohol-based gels produced in Brazil, according to the European
standard EN1500. This study concluded that the gels have an effective disinfecting action equal to
that obtained using 70% ethanol. Its antiviral activity was demonstrated in the studies carried out
by Pandejpong et al. (2012).
They determined that there is effective when it is using antibacterial gel to reduce influenza by
studying 1,437 preschool children. This evidence showed that the mandatory use of ethanol-based
gel as classroom hand disinfection could significantly reduce school absenteeism rates by
influenza. The ethanol-based gel is also currently used in hospitals; as mentioned in the studies
carried out by Chávez et al. (2010), they recommend that hospital staff working in places such as
intensive care units (ICUs), neonatal wards, and emergency services. They must have their hand
hygiene by carrying out a wash with soap and water, alternating with ethanol and glycerin-based
gel to keep their hands moisturized.
Currently, there is no legal regulation in México for the manufacture and evaluation of these
products. The European community uses the UNE EN 1500 standard, which sets the antimicrobial
evaluation procedures of sanitizing products. Still, it does not mention the banning of possibly
toxic substances in its preparation. Due to the COVID-19 disease pandemic, the US Food and Drug
Administration (FDA) issued guidelines to communicate its policy regarding the chemical
composition of certain ethanol-based hand sanitizers by pharmacists in establishments licensed by
the state or federal facilities. They also published a guide, "Temporary Policy for Manufacture of
Alcohol for Incorporation into Alcohol-Based Hand Sanitizer Products during the Public Health
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Emergency (COVID-19) Guidance for Industry". This document contains guidelines for using ethyl
alcohol as an active pharmaceutical ingredient (API) to prepare and distribute hand sanitizer as a
product for public use. This document, issued in March 2020, will be temporarily allowed respect
to certain impurities at levels that can be tolerated for a short time, thought out the COVID-19
public health emergency.
Impurities
Maximum limit
%
ppm
Methanol
0.063
630
Benzene
0.0002
2
Acetaldehyde
0.005
50
Acetyl (1,1-diethoxyethane)
0.005
50
Sum of other impurities
0.03
300
Values in Table 1 shows methyl alcohol (methanol) as the primary contaminant. Ethanol used to
make sanitizers could contain methanol as a contaminant in two ways: the first could be due to the
ethanol decomposition by heating. The second is due to a deliberate addition to save costs since
methanol is cheap. Methanol is metabolized in the liver, much slower than ethanol, by the enzyme
alcohol dehydrogenase activity, producing formaldehyde and formic acid, as shown in Figure 1.
Both metabolites cause severe metabolic acidosis and other organ damage. The produced cellular
acidosis increases by accumulating lactic acid due to secondary cellular hypoxia (UNAM, 2014).
Fig 1. Ethanol and Methanol metabolism diagram. Ethanol produces non-toxic byproducts compared to
methanol (UNAM, 2014).
Fig 1. Diagrama de metabolismo de etanol y metanol. El etanol produce subproductos no tóxicos en
comparación con el metanol (UNAM, 2014).
A Material Safety Data Sheet (MSDS) of methanol indicates that skin contact generates moderate
irritation. It can be absorbed through the skin in harmful amounts. Prolonged and or repetitive
contact can cause dry skin and dermatitis. Methanol can be absorbed through the skin, producing
systemic effects that include visual disturbances (Fisher. 2020).
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This work focuses on the qualitative and quantitative composition analysis of commercial and
collected sanitizing gels using infrared spectrometry and gas chromatography (CG) to evaluate
their ethanol and methanol content percentage for each one.
2. Experimental
2.1 Samples
Fifteen (new and sealed) commercial sanitizing gels produced by national and international
companies were purchased in different stores and they made chemical analyses. In addition, nine
gels samples were analyzed too; they were collected from public areas such as banks, factories,
convenience stores, and shopping centers in Chihuahua City, Mexico, in June 2020. About the
public places collected samples; their brands were not recorded because this information was not
visible. To analyzed gels acquired in the store, they were opened and shaken for 10 minutes before
the analysis. The sealed commercial sanitizing gels were numbered (1 to 15) and, the collected
samples, were labeled by letters (A to I); it was made due to the confidential protocols.
2.2 Chemical reagents
High purity methanol (JT Baker 99.8%) and ethanol (JT Baker 99.8%) were used as a reference to
instrument calibration and also to corroborate their detection limit furthermore optimal operation
of the infrared spectrometer and gas chromatograph.
2.3 Fourier Transform Infrared (FTIR) Spectroscopy
For the FTIR analysis, a Shimadzu model IR Affinity 1S spectrometer was used. The spectra were
obtained by reflectance using the accessory called ATR (Total Attenuated Reflectance by its
acronym in English), Smiths brand, Quest model, with a single reflection diamond window
(bounce) with 20 scans to obtain each spectrum. It was used to qualitatively identify the presence
of the alcohol type present in the gels. FTIR spectra were recorded in the interval between 900 and
1200 cm-1.
2.4 Gas Chromatography
For GC analysis, a Perkin Elmer equipment, model Auto system XL, with a Porapak Q packed
column with 6 feet length and 1/8 inch in diameter, was used. The used chromatographic
procedure temperature was: injection 220 °C, detector: TCD 220 °C, the carrier gas was helium at
30 mL/min (Praxair 99.99%), the oven program was an initial temperature of 105 °C/min with 10
°C/min ramp up to 200 °C and a holding isothermal of 5 min. The quantification procedure was
carried out, preparing calibration curves with a reactive grade of ethanol and methanol. The
samples for analysis were injected directly from the container without previous preparation.
3. Results and discussion
In this part, the qualitative analysis by FTIR infrared spectroscopy of the mixtures used for
calibration can be noticed. Then, the spectra of the purchased and collected sanitizing gels sets are
shown. Finally, the comparative graphs with the quantitative values obtained by gas
chromatography are presented.
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3.1 Qualitative analysis by FTIR spectroscopy
The detection of different alcohols (methanol, isopropanol, and ethanol) contents in the sanitizing
gels were determined, comparing with the standard mixtures' spectra. Their fingerprints spectra
were taken in the FTIR spectra between 1200 and 900 cm-1, identifying specific wavenumbers at
1020 and 1115 cm-1 for methanol, at 1046 and 1088 cm-1 for ethanol, at 966, 1015 and 1053 cm-1 for
propanol also at 950 and 1129 cm-1 for isopropanol, they were present at Figure 2a. These results
are identical to those reported by Coldea et al. (2013).
The spectra for sealed commercial sanitizing gels are shown in Figure 2b. This figure shows the
comparison among the set of spectra acquired for each sample. Most of them contain ethanol and
methanol, but it can be noticed that samples 8, 9, and 13 present methanol in considerable high
amounts. Based on this qualitative analysis, some samples contents toxic compound (methanol).
The spectra for collected sanitized gels samples are shown in Figure 2c. These spectra show evident
the presence of the different types of alcohols. For the set, there is no methanol presence, it does not
appear, but other types of alcohols such as propanol and isopropanol were detected. In this case,
these alcohols are allowed for disinfecting purposes too.
With the FTIR technique, their qualitative identification was carried out. It is also possible to make
a rough quantification by detecting the intensities variation because the intensity of the signals is
proportional to the content (but the precision has low accuracy).
3.2 Quantitative analysis by GC
Through this analytical technique, ethanol, methanol, isopropanol, propanol, and water were
determined quantitatively (in weight percent). Table 2 shows the quantified values for the 15
sealed commercial samples. It is noticeable that only one trademark meets the minimum
requirement of ethanol content (70 %) and another one is close, as indicated on its labels and the
guidelines established by the FDA. The implication of these results is; if commercial products do
not contain the minimum active ingredient (ethanol or isopropanol), the required antimicrobial
function will be diminished with the consequent increase of infected people. It can be noticed;
approximately 47% of studied products (7 samples) do not even meet 50% of ethanol content (in
contrast with 70% required). In the most severe cases, some commercial brands replaced ethanol
with methanol, with the consequent harmful absorption problem in the skin and its possible health
consequences mentioned above (intoxication). In addition, these products do not have a
disinfectant function, but they cause the spread of the virus.
In the case of quantification for collected sanitizers (Table 3), methanol was not found, but it was
found in the commercial gels; none met the optimal ethanol content. For gels that don’t meet the
concentration standards, they accelerate the virus spread, which has severe consequences for
public health by increasing the spread of COVID-19.
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Fig. 2 FTIR spectra for a) reagent grade ethanol, methanol, isopropanol, and propanol - calibration samples, b)
sealed commercial sanitizing gels, and c) collected sanitizing gels (from public facilities places).
Fig. 2 Espectros FTIR para a) etanol, metanol, isopropanol y propanol de grado reactivo - muestras de
calibración, b) geles desinfectantes comerciales sellados y c) geles desinfectantes colectados (desde
instalaciones públicas).
1200 1150 1100 1050 1000 950 900
0.0
0.2
0.4
0.6
0.8
propanol
isopropanol
ethanol
Absorbance
Wavenumber (cm
-1
)
methanol
a)
1200 1150 1100 1050 1000 950 900
0.0
0.1
0.2
0.3
0.4
0.5
ethanol
ethanol
methanol
Absorbance
Wavenumber (cm
-1
)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
b)
methanol
1200 1150 1100 1050 1000 950 900
0.0
0.1
0.2
0.3
0.4
propanol
isopropanol
Absorbance
Wavenumber (cm
-1
)
A
B
C
D
E
F
G
H
I
ethanol
ethanol
c)
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Table 2. Summary chart with ethanol, water, and methanol content determinate by GC in sealed commercial
sanitizers (in weight percent).
Tabla 2. Resumen del contenido de etanol, agua y metanol determinado por GC en desinfectantes comerciales
sellados (en porcentaje en peso).
Sample
Ethanol
Water
Methanol
1
55.3*
44.7
ND
2
64.4*
35.6
ND
3
56.2*
43.8
ND
4
68.7*
31.3
ND
5
51.2*
48.1
0.6**
6
52.8*
47.2
ND
7
48.8*
51.2
ND
8
14.6*
55.1
30.3**
9
0.8*
40.3
58.9**
10
32.0*
67.7
0.3**
11
36.0*
64.0
ND
12
70.0
30.0
ND
13
12.6*
35.6
51.8**
14
57.7*
42.3
ND
15
38.1*
61.9
ND
* Does not meet to 70% ethanol specification
** Methanol content is higher than the maximum allowed by the FDA and ND means not detected.
Table 3. Summary chart with ethanol, water, isopropanol, and propanol quantitative determination in
collected sanitizers (in weight percent).
Tabla 3. Cuadro resumen con determinación cuantitativa de etanol, agua, isopropanol y propanol en
desinfectantes recolectados (en porcentaje en peso).
Sample
Ethanol
Water
Isopropanol
Propanol
A
59.7*
40.2
0.1
ND
B
59.1*
40.9
ND
ND
C
55.7*
44.3
ND
ND
D
54.9*
45.1
ND
ND
E
49.6*
50.4
ND
ND
F
25.3*
74.7
ND
ND
G
16.0*
64.6
19.4
ND
H
9.5*
69.0
10.7
10.8
I
6.5*
75.7
ND
17.7
Does not meet 70% ethanol specification and ND means not detected.
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To notice better the comparison between both sets of samples, data from Tables 2 and 3 were plot.
Figure 3a shows the values plotted for sealed commercial sanitizers. This figure clearly shows the
variation in the quantitative compositional content. The presence of the toxic substance (methanol)
is seen in three brands in alarming amounts (30 to 60%), with a complement of water as the
missing percentage, for sanitizers that contain ethanol but do not meet the proper amount (the
remainder is water). Thus, these gels do not fulfill their prevention effectiveness; these products
play the role of spreading the virus further. Hence, this is important that these products must meet
the appropriate requirements. On the other hand, samples 5 and 10 also contain 0.6 and 0.3%
methanol, respectively; they do not visualize on their FTIR spectra, this technique is not suitable to
determine amounts lesser than 10% (wt./wt.)
Figure 3b shows the graphed values for the sanitizers collected from public places. As can be seen,
the presence of propanol and isopropanol does not agree with the minimum recommended content
that must have to avoid the virus spread. Consequently, these gels would also be spreading the
virus because they do not fulfill the requirements to inhibit the spread. These are even more
dangerous since they are being used in public places, where traffic of people is higher.
4. Conclusions
The gas chromatography technique is a valuable tool to perform analytical quantification for
quality purposes in sanitizing gels by quantifying the alcohol content quickly and accurately
Appropriate ethanol or isopropanol content is essential for correct hand sanitization porpoise. The
analyzes carried out show a severe flaw in the formulation of the sealed commercial gels and those
collected from public facilities because they do not meet the minimum ethanol content (14 samples
of 15) and (9 samples of 9), respectively. Even when they mark an active content of 70% on their
labels, this creates false confidence in the consumer, causing them to become infected by not
complying with the appropriate sanitizing action of the gel. Analytical techniques also showed that
25% of the studied gels contain methanol in amounts that could cause public health problems. The
COVID-19 pandemic has regulatory agencies out of work, creating this type of adulterations in
sanitizing gels. Thus, the implicated companies should self-regulate for social good in a state of
sanitary emergency. It is clear that during this health crisis, these products will continue to be used
regularly, so it is a priority to establish norms and guidelines on their composition.
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Fig. 3 Graph with the content distribution of components in a) sealed commercial sanitizing gels and b)
collected samples from public places. They were ordered from the lowest to highest content of ethanol and
isopropanol, respectively.
Fig. 3 Gráfica con la distribución del contenido de componentes en a) geles desinfectantes comerciales sellados
y b) muestras recolectadas de lugares públicos. Se ordenaron del menor al mayor contenido de etanol e
isopropanol, respectivamente.
2 4 6 8 10 12 14
0
10
20
30
40
50
60
70
80
minimum ethanol
Content (% w/w)
Sealed commercial sanitizing gels
Ethanol
Water
Methanol
maximum water
a)
0
10
20
30
40
50
60
70
80
I
H
F
EG
D
C
B
minimum ethanol
Content (% w/w)
Collected samples
Ethanol
Water
Isopropanol
Propanol
maximum water
b)
A
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2021 TECNOCIENCIA CHIHUAHUA.
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