A robust method for ecigarette FDA-CTP PMTA guidance analytes: Methylacetate, ethylacetate, isobutylacetate, isoamylacetate, benzylacetate 2021_TSRC09_ZhuJeff.pdf

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ANALYSIS OF ORGANIC ACETATES IN E-VAPOR PRODUCTS
BY GC-MS/MS
Jeff Zhu, Charles Brooks and Lee Gentry
ITG Brands LLC, Greensboro, NC, USA
Abstract
Organic acetates (methyl acetate, ethyl acetate, isobutyl acetate, isoamyl acetate
and benzyl acetate) are flavorants and are of interest for E-vapor products testing
based on recent guidance from FDA-CTP (Ref 1). A review of the literature shows
few, if any, direct-application methods for these analytes. Herein we wish to present a
GC-MS/MS method for the analysis of these acetates in e-vapor product aerosols
and e-liquids. These organic compounds have a wide range of boiling points with
methyl acetate being most volatile and ethyl acetate being the second. Since they
can elute around the same retention time as the solvent, it is important to have the
right solvent for GC separations. Various solvents have been tested and acetonitrile
is most suitable which provides good separations from these volatile acetates. In
addition, split injection (30:1) is applied in order to further ensure good separations.
Since these acetates have good thermostability, the inlet temperature is set at 295 °C
to allow for rapid vaporizing of all the analytes and removal of propylene glycol and
glycerol in the inlet. The calibration range is 20 to 2500 ng/mL for methyl acetate, 80
to 10000 ng/mL for ethyl acetate, 40 to 5000 ng/mL for isobutyl acetate and isoamyl
acetate, and 8 to 1000 ng/mL for benzyl acetate. Furfural-d4 is used as internal
standard for benzyl acetate, while ethyl-2,2,2-d3 acetate is used as internal standard
for other four acetates. The LOQ of the method is defined as lowest spiking level
during the validation which ranges from 8 – 80 ng/mL for various analytes above, or
3.2 – 32 ng/puff for 50 puffs of aerosols, or 0.44 – 4.4 µg/g for 0.36 g of e-liquids. The
new method has been validated with good recoveries for e-vapor product aerosols
(87 – 112 %) and e-liquids (79 – 124 %).
Method
Aerosol from test E-vapor products is generated under conditions specified by
the collection regime and collected in one impinger containing 19.8 mL of
acetonitrile that is immersed in an ice/water bath and without glass fiber filter
pads being used. After vaping, an exact amount of internal standards solution
(0.2 mL) is added to the acetonitrile solution from the impinger. For the e-
liquids, approximately 0.36 g of the sample are extracted in 19.8 mL of
acetonitrile along with internal standards solution on an orbital shaker at 300
rpm for 30 minutes. The sample solutions are filtered and subsequently
analyzed by GC-MS/MS (Agilent 7890A/G7001B) in positive electron
ionization mode.
GC Conditions
GC column: DB-1701, 30 m × 0.25 mm ID × 1 μm
Carrier gas: Helium at 1.0 mL/min constant flow
Septum Purge Flow: 3 mL/min
Inlet temperature: 295 °C
Injection mode: Split 30:1
Gas saver: 20 mL/min after 3 min
Injection volume: 1 µL
Column temperature: 35 °C (4 min), 5 °C/min to 50 °C,
25 °C/min to 295 °C (hold for 1 min)
Total runtime: 17.8 min
S/N at Low Standard levels
*: to quantitate the concentrations around LOQ levels
Conclusions
ITG Brands has developed a GC-MS/MS method for the analysis of organic
acetates in both E-vapor product aerosols and e-liquids with simple sample
preparations and 17.8 minutes instrument run time. It covers acetates with a
wide range of volatilities. The method has been validated with good accuracies
and used for routine testing of commercial E-vapor products.
References
1) Premarket Tobacco Product Applications for Electronic Nicotine Delivery
Systems - Guidance for Industry, FDA Center for Tobacco Products, June
2019.
Results
Calibration Curves
Chromatograms for Standard Level 1
Mass Spectrometry Parameters
Transfer line temperature: 295 °C
Source temperature: 230 °C
Quadrupole 1 temperature: 150 °C
Quadrupole 2 temperature: 150 °C
MS Mode: EI/MRM
Nitrogen Collision Flow: 1.5 mL/min
Helium Quench Flow: 2.25 mL/min
Detector off: between 4.45 and 5.8 minutes, after 15 minutes
Quantitation Ions
Recoveries
Compound
Precursor
Ion
Product
Ion
Collision
Energy
Retention
Time (min)
Dwell
Time (ms)
Time
Segment
Methyl Acetate 74 43 3 ~ 3.9 500 1
Ethyl Acetate 70 55 3 ~ 6.5 250 2
Ethyl Acetate-d3 72 57 3 ~ 6.4 250 2
Isobutyl Acetate 73 43 3 ~ 9.9 250 3
Isoamyl Acetate 70 55 6 ~ 11.1 250 4
Furfural-d4 100 98 10 ~ 11.5 300 5
Benzyl Acetate 150 108 3 ~ 13.8 200 6
Sample Type Spike Level Methyl Acetate Ethyl Acetate Isobutyl Acetate Isoamyl Acetate Benzyl Acetate
Low Spike 91% 99% 91% 101% 100%
Mid Spike 99% 98% 99% 109% 103%
High Spike 94% 94% 94% 112% 102%
Low Spike 91% 106% 87% 89% 100%
Mid Spike 97% 99% 97% 112% 104%
High Spike 92% 92% 90% 107% 103%
Low Spike 91% 100% 103% 96% 107%
Mid Spike 103% 106% 107% 124% 107%
High Spike 107% 104% 105% 121% 106%
Low Spike 92% 91% 97% 79% 115%
Mid Spike 105% 102% 100% 107% 110%
High Spike 104% 99% 99% 114% 110%
E-Liquid 2
Aerosol 1
Aerosol 2
E-Liquid 1
Methyl Acetate/Ethyl Acetate-d3 Benzyl Acetate/Furfral-d4
Ethyl Acetate Isobutyl Acetate Isoamyl Acetate
Ethyl Acetate
R2 = 0.99994
Methyl Acetate
R2 = 0.99996
Isobutyl Acetate
R2 = 0.99996
Isoamyl Acetate
R2 = 0.99991
Benzyl Acetate
R2 = 0.99960
Level Methyl Acetate Ethyl Acetate Isobutyl Acetate Isoamyl Acetate Benzyl Acetate
Std 1S* 210(10ng/mL) 88(40ng/mL) 67(20ng/mL) 38(20ng/mL) 64(4ng/mL)
Std 1 238(20ng/mL) 169(80ng/mL) 85(40ng/mL) 75(40ng/mL) 161(8ng/mL)
2021_TSRC09_ZhuJeff.pdf
TSRC2021(74)
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