ma e ials
A icle
Iden i ica ion o Vola ile and Semi-Vola ile Compounds in
Polyme ic Coa ings Used in Me al Cans by GC-MS and SPME
Pa icia Vázquez-Lou ei o , An ía Les ido-Ca dama , Raquel Sendón , Julia López-He nández ,
Pe ec o Pasei o-Losada and Ana Rod íguez-Be naldo de Qui ós *


Ci a ion: Vázquez-Lou ei o, P.;
Les ido-Ca dama, A.; Sendón, R.;
López-He nández, J.; Pasei o-Losada,
P.; Rod íguez-Be naldo de Qui ós, A.
Iden i ica ion o Vola ile and
Semi-Vola ile Compounds in
Polyme ic Coa ings Used in Me al
Cans by GC-MS and SPME. Ma e ials
2021,14, 3704. h ps://doi.o g/
10.3390/ma14133704
Academic Edi o : Csaba Balázsi
Recei ed: 2 June 2021
Accep ed: 28 June 2021
Published: 2 July 2021
Publishe ’s No e: MDPI s ays neu al
wi h ega d o ju isdic ional claims in
published maps and ins i u ional a il-
ia ions.
Copy igh : © 2021 by he au ho s.
Licensee MDPI, Basel, Swi ze land.
This a icle is an open access a icle
dis ibu ed unde he e ms and
condi ions o he C ea i e Commons
A ibu ion (CC BY) license (h ps://
c ea i ecommons.o g/licenses/by/
4.0/).
Depa men o Analy ical Chemis y, Nu i ion and Food Science, Facul y o Pha macy, Uni e si y o San iago de
Compos ela, 15782 San iago de Compos ela, Spain; pa icia azquez.lou ei [email p o ec ed] (P.V.-L.);
[email p o ec ed] (A.L.-C.); [email p o ec ed] (R.S.); [email p o ec ed] (J.L.-H.);
[email p o ec ed] (P.P.-L.)
*Co espondence: ana. [email p o ec ed]; Tel.: +34-88-181-4965
Abs ac :
Polyme ic coa ings a e used as a p o ec i e laye o p ese e ood o be e age quali y
and p o ec i om co osion and a oid a me allic as e. These ypes o ma e ials can con ain some
chemicals ha a e suscep ible o mig a e o ood and cons i u e a isk o consume s’ heal h. This
s udy is ocused on he iden i ica ion o ola ile and semi- ola ile low molecula weigh compounds
p esen in polyme ic coa ings used o me al ood and be e age cans. A me hod based on solid–
liquid ex ac ion ollowed by gas ch oma og aphy–mass spec ome y (GC-MS) was op imized o
he semi- ola ile compounds. Di e en sol en s we e ied wi h he aim o ex ac ing compounds
wi h di e en pola i ies. Fu he mo e, a me hod based on solid-phase mic oex ac ion (SPME) in
headspace (HS) mode and gas ch oma og aphy coupled wi h mass spec ome y (HSSPME-GC-MS)
was de eloped o he iden i ica ion o po en ial ola ile mig an s in polyme ic coa ings. Some
pa ame e s such as ex ac ion ime, equilib ium empe a u e, o he ype o ibe we e op imized.
Di e en compounds, including aldehydes such as oc anal o nonanal, alcohols such as
α
- e pineol
o 2-bu oxye hanol, e he s, alkenes, o ph halic compounds, among o he s, we e iden i ied and
con i med wi h analy ical s anda ds bo h ia SPME analysis as well a e sol en ex ac ion.
Keywo ds: po en ial mig an s; polyme ic coa ings; GC-MS; SPME
1. In oduc ion
Mig a ion o componen s om ood con ac ma e ial o ood is a ma e o conce n
om he ood sa e y poin o iew. Special a en ion has been paid o low molecula weigh
compounds and pa icula ly o unknown compounds. Thei iden i ica ion is a cu en
challenge in he ood packaging ield [1].
Di e en ma e ials ha e adi ionally been used in ood packaging including glass,
me als, pape , pape boa ds, and plas ics. Ma sh e al. [
2
] epo ed some ad an ages
and disad an ages o hese ypical ma e ials used in be e age packaging, such as he
suscep ibili y o b eakages o he hea y weigh in he case o glass. Me al cans a e widely
used, and hey ha e se e al ad an ages o e o he ma e ials as hey a e able o ole a e
high empe a u e and p essu e condi ions [
3
]. Polyme ic coa ings a e used as unc ional
ba ie s be ween ood and me al cans. They p ese e he quali y o ood in e ms o la o ,
odo , and colo , as well as ex end shel -li e and help he me al can in p o ec ing ood om
ex e nal agen s such as ligh , oxygen, and mic oo ganisms, and acili a e anspo and
s o age o he canned ood.
Be e age packaging o en combines se e al ma e ials o exploi hese p ope ies.
Mul ilaye sys ems, new app oaches based on ac i e o in elligen packaging o ma e ials
wi h lowe en i onmen al impac s a e in de elopmen [2].
Be e age cans a e one o he mos used mul ilaye packaging ma e ials, made o
aluminum wi h an inne epoxy esin coa ing o p e en di ec con ac be ween ood o
Ma e ials 2021,14, 3704. h ps://doi.o g/10.3390/ma14133704 h ps://www.mdpi.com/jou nal/ma e ials
Ma e ials 2021,14, 3704 2 o 14
be e age and he aluminum su ace [
4
]. Final coa ings a e ob ained by he addi ion
o componen s such as c oss-linke s, sol en s, pigmen s, an i- oaming agen s, adhesion
p omo e s, esins, and su ac an s [
5
]. Du ing he polyme iza ion p ocess, side eac ions
can occu , and linea o cyclic byp oduc s may be o med. These unknown chemicals may
mig a e in o ood esul ing in consume exposu e [6].
Epoxy esins a e comme cially used in coa ings because o hei excep ional adhesion
due o he p esence o pola hyd oxyl and e he g oups in hei s uc u e [
7
]. Besides his
echnical ad an age, some d awbacks ega ding hei sa e y can be ound in he li e a u e;
some au ho s ha e shown he po en ial mig a ion o bisphenol A (BPA) om hese ma e ials
o ood [
8
]. Epoxy monome s such as bisphenol A-diglycidyl e he (BADGE) ha e been
ex ac ed om epoxy esins [
9
] and ound in ood simulan s a e mig a ion assays [
10
],
and o he BADGE-based de i a i es om epoxy coa ings we e also iden i ied by Schae e
e al. [11].
Commission Regula ion (EU) No. 10/2011 [
12
] es ablished speci ic ules o plas ic
ma e ials in ended o come in con ac wi h ood. Cu en ly, he e is no speci ic Eu opean
legisla ion o coa ings. Bo h in en ionally added subs ances (IAS) and non-in en ionally
added subs ances (NIAS) such as impu i ies, eac ion byp oduc s, and deg ada ion p od-
uc s can mig a e in o ood, and hey should be e alua ed.
These mig an s may also be oligome s, p epolyme s, ca alys , eac ion accele a o s,
epoxidized edible oils, es e s, waxes, lub ican s, me als, e c. [
13
,
14
]. The mig a ion o
hese chemicals om packaging o ood and be e age is one o he main conce ns o ood
sa e y au ho i ies.
Non- a ge ed me hods using LC-MS o GC-MS a e being widely employed o he
iden i ica ion o po en ial mig an s in ood packaging. Bo h echniques p o ide essen ial
and complemen a y in o ma ion necessa y o a comple e cha ac e iza ion o packaging
ma e ials. In GC-MS analysis, he use o comme cial lib a ies helps he iden i ica ion, al-
hough in he case o NIAS, hey usually a e no p esen in he da abases. B adley e al. [
15
]
ca ied ou an analysis ia headspace GC-MS and a sol en ex ac ion wi h ace oni ile
ollowed by GC-MS o de e mine ola ile compounds in epoxy phenolic can coa ings. The
au ho s de ec ed bisphenol A, used as a s a ing subs ance in he manu ac u ing o he coa -
ing. Mo e ecen ly, Ome e al. [
16
] used GC-MS wi h di e en ioniza ion sou ces, namely
elec on ioniza ion (EI) and a mosphe ic p essu e chemical ioniza ion (APCI), and di e en
mass spec ome e s, speci ically quad upole, ime-o - ligh , and o bi ap, o in es iga e
po en ial mig an s in polyes e –polyu e hane lacque s. Se e al cyclic oligoes e e ame s
we e iden i ied in he wo lacque s es ed. In ano he s udy epo ed in he li e a u e,
GC-MS and highly accu a e mass spec ome y was used o he analysis o bisphenol A al-
e na i e ood-con ac me al can coa ings. Cyclic polyes e oligome s om polyes e -based
coa ings and bisphenol- ype compounds, including e ame hyl bisphenol F, e ame hyl
bisphenol F diglycidyl e he , and bisphenol F, among o he s, we e iden i ied [3].
The aim o his wo k was o de elop a sc eening me hod o he iden i ica ion o ola ile
compounds in polyme ic coa ings o me al cans o be e age packaging. Fo ha pu pose, a
me hod based on solid–liquid ex ac ion ollowed by gas ch oma og aphy–mass spec ome y
(GC-MS) and a me hod based on solid-phase mic oex ac ion in headspace mode and gas
ch oma og aphy coupled wi h mass spec ome y (HSSPME-GC-MS) we e op imized.
2. Ma e ials and Me hods
2.1. Sample Desc ip ion and FTIR Cha ac e iza ion
A o al o en be e ages packed in me al cans we e bough in local supe ma ke s
in San iago de Compos ela (Spain). All o hem we e wo-piece cans. The in e nal su -
ace o me al cans is o en coa ed wi h a polyme ic coa ing (wi h a hickness o abou
2µm) o p ese e ood and a oid me al co osion. The hickness o he samples analyzed
(
me al + coa ing
) is p o ided in Table 1. The hickness o he packaging was measu ed
wi h a manual digi al mic ome e (Mi u oyo-Japan, Kanagawa, Japan). The polyme ic
coa ings we e analyzed by using an a enua ed o al e lec ance FTIR spec ome e and
Ma e ials 2021,14, 3704 3 o 14
we e iden i ied using he KnowI All
®
17.4.135.B IR Spec al Lib a ies o Polyme s and
Rela ed Compounds (Bio-Rad Labo a o ies, Inc., He cules, CA, USA).
Table 1. Sample desc ip ions.
Code Be e age Polyme ic Coa ing Thickness (µm)
BC01 T adi ional Bee
La . Ex .: PU
La e al: 114.5
Lid: 313.0
La . In .: Phx
Lid In .: Phx
Lid Ex .: Phx
BC02 Vodka mixed d ink
La . Ex .: PU
La e al: 109.0
Lid: 218.0
La . In .: Phx
Lid In .: Epx
Lid Ex .: Epx
BC03 Mixed lemon la ou
La . Ex .: PU
La e al: 104.0
Lid: 218.0
La . In .: Phx
Lid In .: Phx
Lid Ex .: Phx
BC04 Ene gy D ink Ze o
La . Ex .: PU
La e al: 112.0
Lid: 264.0
La . In .: Phx
Lid In .: Epx
Lid Ex .: Epx
BC05 S a Wa s Space
Punch
La . Ex .: PP
La e al: 114.0
Lid: 331.0
La . In .: Ac ylic
Lid In .: Polyes e
Lid Ex .: Phx
BC06 G een cola
La . Ex .: PU
La e al: 115.0
Lid: 234.0
La . In .: Phx
Lid In .: Phx
Lid Ex .: Phx
BC07 Tonic o iginal
La . Ex .: PU
La e al: 111.0
Lid: 258.0
La . In .: Phx
Lid In .: Epx
Lid Ex .: Epx
BC08 Tonic wa e o iginal
La . Ex .: PU
La e al: 113.0
Lid: 230.0
La . In .: Phx
Lid In .: Epx
Lid Ex .: Epx
BC09 P emium onic wa e
La . Ex .: PU
La e al: 123.0
Lid: 226.0
La . In .: Ac ylic
Lid In .: Polyes e
Lid Ex .: Phx
BC10 Na u al mine al
wa e d ink
La . Ex .: PU
La e al: 103.0
Lid: 248.0
La . In .: Phx
Lid In .: Epx
Lid Ex .: Epx
Epx: Epoxy esin; Ex .: ex e nal; In : In e nal; La : La e al; Phx: Phenoxy esin; PP: Polyp opylene;
PU: Polyu e hane.
The pH o he be e age samples anged be ween 2.56 and 6.60. A b ie o e iew o
he samples is p esen ed in Table 1; and a mo e de ailed desc ip ion o he samples used in
his s udy was desc ibed by Les ido-Ca dama e al. [17].
Ma e ials 2021,14, 3704 4 o 14
2.2. Sample T ea men
2.2.1. Sol en Ex ac ion P ocedu e
Samples we e opened, emp ied, and washed wi h wa m wa e be o e analysis. Cans
we e cu in o small pieces (app oxima ely 0.5 cm
2
), hen 0.8 g we e weigh ed in a ial
and
5 mL
o me hanol was added and a e wa d he ial was he me ically sealed. The
ex ac ion was pe o med in an o en a 70
◦
C o 24 h. One aliquo was hen emo ed wi h
a 0.22 µm poly e a luo oe hylene (PTFE)-memb ane il e and analyzed ia GC-MS.
2.2.2. SPME P ocedu e
An SPME holde o manual sampling and comme cial ibe s was pu chased om
Supelco (Belle on e, PA, USA). Fibe s wi h di e en coa ing ma e ials we e es ed: a
di inylbenzene-Ca boxen-polydime hylsiloxane (DVB/PDMS/CAR) ibe wi h 50–30
µ
m
hickness and a Ca boxen-polydime hylsiloxane (CAR-PDMS) ibe wi h 100
µ
m hickness.
P io o use hey we e condi ioned by inse ing hem in o he GC injec o acco ding o he
supplie ’s ins uc ions: o 1 h a 270 ◦C and 0.5 h a 250 ◦C, espec i ely.
Fo each expe imen , 0.8 g o each sample, p e iously cu in o small pieces (app oxi-
ma ely 0.5 cm
2
) we e weigh ed in o a 20 mL headspace ial and sealed wi h a PTFE- aced
silicone sep um (C omlab, Ba celona, Spain). The SPME ibe was pu in o he ial, and his
was hea ed a 100
◦
C o 30 min. The ibe was hen deso bed in o he GC injec o o 10 min
a 200
◦
C. The compounds abso bed by he ibe we e sepa a ed ia gas ch oma og aphic
analysis and iden i ied using he MS de ec o ope a ing in he desc ibed condi ions below.
2.3. Reagen s and Analy ical S anda ds
Ace oni ile HPLC g ade, me hanol, and hexane GC-MS g ade we e supplied by
Me ck (Da ms ad , Ge many). E hanol o analysis was supplied by Me ck (Da ms ad ,
Ge many). The 2-bu oxye hanol, spec opho ome ic g ade wi h a pu i y o
≥
99.0%, 2,2-
dime hyl-1,3-p opanediol wi h a pu i y o 99.0%, oc anal wi h a pu i y o 99%, D-Limonene,
ε
-Cap olac am; 2,6-Di- e -bu yl-1,4-benzoquinone wi h a pu i y o 98.0%, die hyl ph hala e
wi h a pu i y o 99.5%, benzophenone wi h a pu i y o
≥
99.0%, benzoic acid wi h a pu i y
o 99.5%, anillin wi h a pu i y o 99.0%, 2,4-di e bu ylphenol wi h a pu i y o 99.0%, and
α
- e pineol we e pu chased om Sigma Ald ich (S einheim, Ge many). Nonanal wi h
pu i y o 98.7% was pu chased om Supelco (Belle on e, PA, USA). The 2-phenoxye hanol
wi h pu i y o
≥
99.0% was supplied by Fluka (Seelze, Ge many). Wo king solu ions we e
p epa ed by dilu ing di e en amoun s o he s ock s anda d solu ion in me hanol.
2.4. GC-MS Condi ions o Sol en Ex ac ion Samples
A T ace 1300 gas ch oma og aph equipped wi h a p og ammed spli /spli less injec o ,
a 1310 au osample , and an ISQ LT Single Quad upole mass spec ome e (The mo Elec on
Co p., Madison, WI, USA) we e used o pe o m he GC analyses. The sepa a ion was
pe o med on a Rxi-5Sil MS (30 m
×
0.25 mm
×
0.25
µ
m) column om Res ek (Belle on e,
PA, USA). The ope a ing condi ions we e he ollowing: he injec o empe a u e was
300
◦
C and he empe a u e o he ans e line o he de ec o was 300
◦
C. The o en
empe a u e was se as ollows: ini ially he empe a u e was se a 40
◦
C o 2 min, hen
inc eased a a a e o 9
◦
C/min un il 300
◦
C and held o 12 min. Injec ion was pe o med
in spli less mode, and he injec ion olume was 1
µ
L. The ca ie gas was helium wi h a
low a e o 1 mL/min. The mass spec ome e was ope a ed in elec on impac ioniza ion
mode wi h a ull scan ange be ween 20 and 500 m/z.
Da a analysis was pe o med using Xcalibu e sion 4.1 and he NIST/EPA/NIH 11
mass spec al lib a y ( e sion 2.0) and Wiley Regis y TM 8 h edi ion da abase we e used
o iden i ica ion.
2.5. GC-MS Condi ions o SPME Analysis
A The mo Finnigan T ace GC gas ch oma og aph and a Finnigan T ace DSQ mass
selec i e de ec o (The mo Scien i ic, Wal ham, MA, USA) we e used o pe o m all GC
Ma e ials 2021,14, 3704 5 o 14
analyses. Fo SPME analyses, an Rxi-624Sil MS (30 m
×
0.25 mm
×
1.40
µ
m) column om
Res ek (Belle on e, PA, USA) was used, and he sepa a ion o compounds was pe o med
unde he ollowing ope a ing condi ions: he injec o empe a u e was se a 200
◦
C and
he ans e line empe a u e was 250
◦
C. The amp empe a u e was se om 45 o 250
◦
C.
The mass spec ome e ope a ed in ull scan mode (be ween 20 and 500 m/z).
Da a analysis was pe o med using Xcalibu e sion 2.0.7 and he NIST/EPA/NIH 11
mass spec al lib a y ( e sion 2.0) and Wiley Regis y TM 8 h edi ion da abase we e used
o de ec ion and iden i ica ion.
In o de o es ima e he oxici y o he iden i ied compounds, an in silico me hod,
namely C ame ules we e applied. Fo ha , he so wa e Tox ee was used [
18
]. Acco ding
o C ame ules, subs ances a e classi ied based on hei chemical s uc u e in o Class I (low
oxici y), Class II (in e media e oxici y) and Class III (high oxici y). Thus, Class I com-
p ises subs ances wi h simple chemical s uc u es such as common ca bohyd a es, acyclic
alipha ic hyd oca bons, and so on. Class II includes subs ances ha possess s uc u es
ha a e less innocuous han hose o Class I bu do no con ain subs ances wi h s uc u al
ea u es ha sugges oxici y like subs ances o Class III. Examples o Class II subs ances
a e common componen s o ood, subs ances con aining no unc ional g oups o he han
alcohol, aldehyde, acid, es e , e c. Class III includes subs ances wi h chemical s uc u es
ha may sugges signi ican oxici y o con ain eac i e unc ional g oups. Examples o
subs ances belonging o his Class a e ce ain benzene de i a i es, ce ain he e ocyclic
subs ances, e c. [19].
3. Resul s and Discussion
3.1. Sol en Selec ion o Can Ex ac ion
Di e en sol en s we e es ed wi h he aim o ex ac compounds wi h di e en
pola i ies p esen in he coa ing o me al cans. Samples we e ex ac ed unde di e en
condi ions, bo h me hanol and ace oni ile o 24 h a 70
◦
C, hexane o 4 h a 60
◦
C, and
a mix u e o hexane and e hanol (3:1 / ) o 24 h a 20
◦
C. In Figu e 1, ch oma og ams
ob ained a e ex ac ion wi h di e en sol en s a e shown. Me hanol was he sol en
selec ed o ex ac ion because mo e peaks we e de ec ed and iden i ied. Table 2lis s he
compounds de ec ed a e ex ac ion wi h di e en sol en s. As he analyzed samples we e
al eady in con ac wi h he d ink, some o he iden i ied compounds may ha e hei o igin
in ood. On he o he hand, i is in e es ing o no e ha la o ings a e commonly used in
hese be e ages, hus some o he de ec ed compounds in he samples a e au ho ized as
ood la o ings in he Eu opean Union [
20
]. These compounds a e indica ed in he able
wi h hei co esponding Fla is Numbe (FL No.). Some o hem a e, o example, benzoic
acid me hyl es e and cap ylic acid me hyl es e .
Ma e ials 2021, 14, x FOR PEER REVIEW 6 o 17
Figu e 1. Ch oma og ams o sample BC04 ex ac ed wi h di e en sol en s.
Table 2. Compa ison o he mos abundan de ec ed compounds in sample BC04 using di e en ex ac ion sol en s.
T /min Compound CAS Fl No. MeOH ACN Hex Hex: E OH
(3:1 / )
10.56 Benzoic acid
me hyl es e 93-58-3 09.725 x
11.01 Cap ylic acid
me hyl es e 111-11-5 09.117 x
12.97 Adipic acid
me hyl es e 627-93-0 x
17.17 Lau ic acid
me hyl es e 111-82-0 09.101 x
17.55
Unknown
compound
(m/z 129)
x
18.07 Die hyl
ph hala e * 84-66-2 x x x
19.92 Es e x
20.25
Unknown
compound
(m/z 56)
x
21.71 Thiophene x
25.07
Unknown
compound
(m/z 151)
x
25.56 Adipa e s uc-
u e x x x x
Figu e 1. Ch oma og ams o sample BC04 ex ac ed wi h di e en sol en s.

Ma e ials 2021,14, 3704 6 o 14
Table 2. Compa ison o he mos abundan de ec ed compounds in sample BC04 using di e en ex ac ion sol en s.
T /min Compound CAS Fl No. MeOH ACN Hex Hex: E OH (3:1 / )
10.56 Benzoic acid me hyl es e 93-58-3 09.725 x
11.01 Cap ylic acid me hyl es e 111-11-5 09.117 x
12.97 Adipic acid me hyl es e 627-93-0 x
17.17 Lau ic acid me hyl es e 111-82-0 09.101 x
17.55
Unknown compound (m/z129)
x
18.07 Die hyl ph hala e * 84-66-2 x x x
19.92 Es e x
20.25 Unknown compound (m/z56) x
21.71 Thiophene x
25.07
Unknown compound (m/z151)
x
25.56 Adipa e s uc u e x x x x
25.65 Adipa e s uc u e x x x x
30.43 Unknown compound x x x x
* Subs ances con i med wi h a s anda d solu ion.
Es e compounds we e mainly iden i ied in ex ac ion wi h me hanol as a sol en .
Some s udies show he mig a ion o hese ypes o compounds in cu ed a nishes used
in ood packaging [
21
]. In his wo k, samples we e ex ac ed wi h e hanol 95% ( / ).
Adipic acid has been epo ed as a chemical in e media e used in he manu ac u ing o
polyu e hane esins [22].
3.2. Op imiza ion o SPME Me hod
In he p esen wo k, a me hod based on solid-phase mic oex ac ion in headspace
mode and gas ch oma og aphy coupled wi h mass spec ome y (HSSPME-GC-MS) was
de eloped o he iden i ica ion o po en ial mig an s in polyme ic coa ings.
SPME is an easy, cheap, and clean me hod o use, al hough he e is a o need u he
op imiza ion in e ms o equilib ium o expe imen al condi ions such as hea ing empe a-
u e, ex ac ion ime, sample olume, concen a ion o ola iles, and sample ma ix [
23
].
Fo ha pu pose, some pa ame e s such as ex ac ion ime, equilib ium empe a u e, o
he ype o ibe we e op imized.
The e ec o ex ac ion empe a u e, ex ac ion ime, and deso p ion ime was e alu-
a ed using he ibe DVB-CAR-PDMS.
Fi s ly, he ex ac ion ime was op imized. Di e en imes we e es ed (10, 30, and
60 min
), keeping ex ac ion empe a u e (40, 70, and 100
◦
C), equilib a ion ime (2 min),
and deso p ion ime (10 min) ixed. Unde hese condi ions he bes esul s we e ound a
30 and 60 min o ex ac ion because mo e peaks we e iden i ied and wi h a highe in ensi y,
and he e was ha dly any di e ence be ween he wo es ed imes, he e o e,
30 min
o
ex ac ion was selec ed. Once he ime o ex ac ion was op imized, he empe a u e was
s udied anging om 40 o 100
◦
C. The di e ence in he sensi i i y and he numbe o
peaks de ec ed was ela ed wi h he inc ease o he empe a u e.
The e ec s o empe a u e and ex ac ion ime we e e iden om he ch oma og ams
ob ained unde he ollowing condi ions: 40, 70, and 100
◦
C o 10, 30, and 60 min. An
inc ease in he peak ch oma og aphic a ea was ound, especially wi h he less ola ile
compounds a highe empe a u es.
Machiels e al. [
24
] epo ed ha highly ola ile compounds we e no a ec ed by
deso p ion ime and less ola ile compounds needed mo e ime o deso b.
Ma e ials 2021,14, 3704 7 o 14
The nex pa ame e ha was op imized was he amoun o he sample used, which
was conside ed be ween 0.8 g and 2 g. Finally, he amoun 0.8 g was chosen because la ge
amoun s o sample did no lead o highe in ensi y o he ch oma og aphic peaks.
I is impo an o ge a well-balanced comp omise be ween sensi i i y and ex ac-
ion a e, pa icula ly wi h espec o he ex ac ion empe a u e, o achie e a ca e ul
op imiza ion o each pa ame e .
Bes esul s and wi h he highe peak in ensi ies we e ob ained o 30 min a 100
◦
C
wi h 2 min o equilib a ion ime and 10 min o deso p ion ime.
Selec ion o he Type o Fibe
The selec ion o he ibe and SPME ex ac ion condi ions can a ec he sensi i i y
and accu acy o SPME analysis. Pa k e al. [
25
] a i med ha using wo-phase ibe s
(Ca boxen-PDMS) seems o be mo e sui able o measu ing low molecula weigh com-
pounds, whe eas h ee-phase ibe s (DVB-Ca boxen on PDMS) appea ed o be mo e app o-
p ia e o measu ing high molecula weigh compounds. DVB-CAR-PDMS ibe has shown
he bes so p ion capaci y o some compounds such as ood packaging con aminan s in
alcoholic be e ages.
In ou s udy, a DVB/PDMS/CAR ibe wi h 50–30
µ
m hickness and a CAR-PDMS
wi h 100
µ
m hickness we e es ed. Peak a eas om decanal, 2-oxepanone and die hylph-
hala e, which we e he mos abundan peaks, we e compa ed be ween bo h ypes o ibe s,
wi h he i s one achie ing he highe esponse. This ac con i ms ha DVB/PDMS/CAR
ibe is mo e app op ia e o sepa a e ola ile compounds wi h highe molecula weigh .
3.3. Can Coa ings Analysis ia GC a e a Sol en Ex ac ion
GC-MS was used o en a i ely iden i y semi- ola ile compounds ha could po en-
ially mig a e om polyme ic coa ings. A GC-MS me hod ha co e ed a wide mass ange
( om 35 o 500 m/z) wi h a sui able g adien o empe a u es was used. Samples we e
injec ed in spli less mode. Resul s ob ained a e shown in Table 3. Only compounds wi h
app op ia e di ec ma ching ac o s (SI) and e e se sea ch ma ching (RSI) a e iden i ied in
Table 3. In gene al, alues o 900 o g ea e a e conside ed an excellen ma ch, 800–900 a
good ma ch, and 700–800 a ai ma ch. Fo hose compounds whose iden i ica ion was no
achie able, he mos abundan m/zis speci ied.
Table 3. Compounds iden i ied ia GC-MS analysis a e ex ac ion wi h MeOH as a sol en .
T /min Compound CAS Fl No. SI RSI Sample(s) TC
10.56 Benzoic acid me hyl es e 93-58-3 09.725 745 857 BC04 I
11.01 Cap ylic acid me hyl es e 111-11-5 09.117 701 789 BC04 I
11.37 2-Oxepanone 502-44-3 729 862 BC06, BC07 I
12.34 α-Te pineol * 98-55-5 02.014 902 936 9 III
12.97 Adipic acid me hyl es e 627-93-0 794 867 BC01, BC03, BC04,
BC06–BC08 I
14.2 Isobenzo u an-1,3-dione 85-44-9 841 922 BC02, BC05, BC07,
BC10 III
15.58 Unknown diol BC05
16.93 (+)-Ledene 21747-46-6 893 927 BC09 I
17.17 Lau ic acid me hyl es e 111-82-0 09.101 855 878 BC01–BC10 I
17.55 Es e s uc u e (m/z129) BC01–BC10
18.08 Die hyl ph hala e * 84-66-2 929 938 BC01–BC05, BC09,
BC10 I
18.37
Unknown compound (m/z107, 163)
BC09
19.28 Dodecalac one 2305-05-7 10.019 855 894 BC05 II
19.92 Es e s uc u e (m/z129) BC01–BC10
20.29 Unknown compound (m/z56, 111) BC08
Ma e ials 2021,14, 3704 8 o 14
Table 3. Con .
T /min Compound CAS Fl No. SI RSI Sample(s) TC
20.72 Bu yl oc yl ph hala e 84-78-6 714 758 BC02 I
20.99 Ke one s uc u e BC05, BC07
21.53 Unknown compound m/z(45, 109) BC05
21.73 2-Isobu yl-5-p opyl hiophene 4861-63-6 BC01–BC06,
BC08–BC10 III
21.99
7,9-Di- e -bu yl-1-
oxaspi o[4,5]deca-6,9-diene-2,8-
dione
82304-66-3 BC05 III
22.33 and 23.3 Unknown compound (Ph hala e
s uc u e m/z: 149) BC02, BC05, BC07
23.81 Unknown compound (m/z151) BC06–BC08, BC10
25.08 Unknown compound (m/z151) BC01, BC02, BC04,
BC08–BC10
25.56
Unknown compound (m/z129, 111)
BC01–BC10
25.65
Unknown compound (m/z129, 111)
BC01–BC010
26.53 Unknown compound (m/z163) BC08, BC10
27.19 α-Me hyl-δ-oxo-2-phenyl-1,3-
dioxolane-2-hep aneni ile 58422-90-5 782 940 BC02, BC05, BC07,
BC09, BC10 III
27.42 Hexa(me hoxyme hyl)melamine 68002-20-0 857 874 BC01- BC03, BC05,
BC08, BC10 III
27.87
Unknown compound (m/z143, 111)
BC08
28.4 Unknown compound (Ph hala e
s uc u e m/z149)
BC02, BC05, BC07,
BC09, BC10
29.96 Unknown compound (m/z301) BC02, BC05,
BC09, BC10
30.46 Unknown compound (m/z69, 81) BC08
32.45 Unknown compound (m/z345) BC02, 5 BC0,
BC09, BC10
35.36 Unknown compound (Ph hala e
s uc u e m/z: 149) BC02, BC05, BC010
35.95 Unknown compound (m/z389) BC02, BC05, BC09
* Subs ances con i med wi h a s anda d solu ion.
Vola ile compounds coming om he be e age we e de ec ed. Thus, di e en es-
e s (e.g., benzoic acid me hyl es e , lau ic acid me hyl es e , e c.) we e iden i ied. Es-
e s we e epo ed by D agone e al. [
26
] in alcoholic dis illed be e ages, which con-
ibu e o he g ea es p opo ion o he o al a oma. The analysis was pe o med using
dichlo ome hane as an ex ac ion sol en and he compounds we e sepa a ed on a CP-Wax
52 CB (
50 m ×0.25 mm
i.d., 0.2
µ
m ilm hickness, Ch ompack). Ledene, a sesqui e pene
hyd oca bon, has also been ound in na u al p oduc s [
27
].
α
-Me hyl-
δ
-oxo-2-phenyl-1,3-
dioxolane-2-hep aneni ile has been epo ed as a p ecu so o hymol and a ca ac ol
and eugenol in e media y [
28
]. Mo eo e , la o ings au ho ized in he EU [
20
], such as
α
- e pineol and dodecalac one, we e iden i ied in di e en samples. These subs ances
belong o Class III and Class II, acco ding o C ame ules, espec i ely.
Wi h espec o compounds coming om he packaging ma e ials, se e al plas icize s,
including ph hala es (e.g., die hyl ph hala e, bu yl oc yl ph hala e), we e iden i ied in
almos all samples. Chemicals o ph hala e es e s (PAEs) can ac as endoc ine dis up-
o s and lead o ad e se e ec s on o ganisms e en in a low concen a ion [
29
]. They
can also induce a ious e iological diseases o humans, such as diso de s o he male
ep oduc i e ac , b eas and es icula cance s, and dys unc ion o he neu oendoc ine
sys em [
30
]. Isobenzo u an-1,3-dione, also called ph halic anhyd ide, was iden i ied in
samples BC02, BC05, BC07, and BC10. The mos impo an de i a i es o his compound
Ma e ials 2021,14, 3704 9 o 14
a e plas icize s and also polyes e esins and dyes [
31
]. This compound has been clas-
si ied as high oxici y (Class III), acco ding o C ame ules. Besides, i can be pa o
a cu ing agen sys em used du ing he manu ac u ing o an epoxy esin [
32
]. O he
compounds iden i ied include 2-oxepanone and hexa(me hoxyme hyl)melamine. The
lac one has been epo ed as a deg ada ion p oduc o polyu e hanes and in his s udy
he analysis was ca ied ou by py olysis-gas-ch oma og aphy/mass spec ome y [
33
],
and hexa(me hoxyme hyl)melamine is widely employed as a c oss-linking agen in coa -
ings [
34
]. This compound belongs o Class III, acco ding o C ame ules. A NIAS com-
pound, speci ically 7,9-di- e -bu yl-1-oxaspi o[4,5]deca-6,9-diene-2,8-dione (Figu e 2), was
iden i ied in sample BC05 and i p esen s high oxici y (Class III). This compound has been
epo ed as a deg ada ion p oduc o he an ioxidan I ganox 1010 and has been ound in
se e al samples o bo h plas ic and pape packaging and in polyu e hane adhesi es [
35
,
36
].
In plas ic ma e ials he analy e was de e mined in aqueous ex ac s using he pu ge and
ap me hod combined wi h GC-MS [36].
Ma e ials 2021, 14, x FOR PEER REVIEW 11 o 17
Figu e 2. Chemical s uc u e o 7,9-di- e -bu yl-1-oxaspi o[4,5]deca-6,9-diene-2,8-dione.
Fo some compounds, despi e hei high abundance, iden i ica ion was no possible
wi h he spec al lib a ies a ailable, such as he compounds a 28.4 min (m/z 149, which is
he cha ac e is ic mass o ph hala es compounds), 29.97 min (m/z 301), 32.45 min (m/z 345),
35.37 min (m/z 149), and 35.95 min (m/z 389). De ailed in o ma ion abou he mass spec a
o he uniden i ied compounds is a ailable in he elec onic Supplemen a y Ma e ial.
3.4. Can Coa ings Analysis ia SPME
The compounds de ec ed a e he ex ac ion wi h SPME a e summa ized in Table 4.
Only compounds wi h app op ia e di ec ma ching ac o s (SI) and e e se sea ch ma ch-
ing (RSI) a e included. Fo hose compounds whose iden i ica ion was no achie able, he
mos abundan m/z is speci ied.
Table 4. Compounds iden i ied ia SPME GC-MS analysis.
T
/
min Compound CAS Fl No. SI RSI Sample(s) TC
9.61 P opylene gly-
col 57-55-6 571 818 BC04 I
13.72 2-Bu oxy-
e hanol * 111-76-2 02.242 866 925 BC01–BC10 I
15.37 α-Te pinene 99-86-5 01.019 586 754 BC09 I
15.61 Benzaldehyde 100-52-7 05.013 631 865 BC01, BC05 I
15.85
2,2-Dime hyl-
1,3-P opane-
diol *
126-30-7 821 892
BC01, BC02,
BC03, BC04,
BC08
I
16.11 Oc anal * 124-13-0 05.009 505 701 BC04 I
16.28
1,2,3,4-Te a-
me hyl ben-
zene
488-23-3 849 879 BC09 I
16.43 Limonene * 5989-27-5 01.045 916 924 BC02, BC03,
BC05–BC08 I
16.5 p-Cymene 99-87-6 01.002 909 926
BC02, BC03,
BC06, BC09 I
16.69 1-Hexanol-2-
e hyl 104-76-7 02.082 809 913
BC05, BC06,
BC08 I
17.05 g-Te pinene 99-85-4 01.020 882 894 BC02, BC09 I
17.68 Te pinolene 586-62-9 01.005 795 864 BC02 I
18.07 Benzene s uc-
u e
BC02, BC05,
BC07, BC09
Figu e 2. Chemical s uc u e o 7,9-di- e -bu yl-1-oxaspi o[4,5]deca-6,9-diene-2,8-dione.
Fo some compounds, despi e hei high abundance, iden i ica ion was no possible
wi h he spec al lib a ies a ailable, such as he compounds a 28.4 min (m/z149, which is
he cha ac e is ic mass o ph hala es compounds), 29.97 min (m/z301), 32.45 min (m/z345),
35.37 min (m/z149), and 35.95 min (m/z389). De ailed in o ma ion abou he mass spec a
o he uniden i ied compounds is a ailable in he elec onic Supplemen a y Ma e ial.
3.4. Can Coa ings Analysis ia SPME
The compounds de ec ed a e he ex ac ion wi h SPME a e summa ized in Table 4.
Only compounds wi h app op ia e di ec ma ching ac o s (SI) and e e se sea ch ma ching
(RSI) a e included. Fo hose compounds whose iden i ica ion was no achie able, he mos
abundan m/zis speci ied.
Table 4. Compounds iden i ied ia SPME GC-MS analysis.
T /min Compound CAS Fl No. SI RSI Sample(s) TC
9.61 P opylene glycol 57-55-6 571 818 BC04 I
13.72 2-Bu oxye hanol * 111-76-2 02.242 866 925 BC01–BC10 I
15.37 α-Te pinene 99-86-5 01.019 586 754 BC09 I
15.61 Benzaldehyde 100-52-7 05.013 631 865 BC01, BC05 I
15.85 2,2-Dime hyl-1,3-P opanediol * 126-30-7 821 892 BC01, BC02, BC03,
BC04, BC08 I
16.11 Oc anal * 124-13-0 05.009 505 701 BC04 I
16.28 1,2,3,4-Te ame hyl benzene 488-23-3 849 879 BC09 I
16.43 Limonene * 5989-27-5 01.045 916 924 BC02, BC03,
BC05–BC08 I