Figure 1
HPLC gradient conditions for benzoic acid and benzyl alcohol analysis_
| Run time | Flow rate | Mobile phase A | Mobile phase B |
|---|---|---|---|
| (min) | (mL/min) | Composition (%) | Composition (%) |
| 0.0 | 0.225 | 80 | 20 |
| 2.0 | 0.225 | 30 | 70 |
| 11.0 | 0.225 | 30 | 70 |
| 12.0 | 0.250 | 80 | 20 |
Levels of benzyl alcohol (n = 21), benzoic acid (n = 21), and nicotine (n = 7) in JUULTM liquids and two commercially available e-liquids_
| Sample type | Benzyl alcohol Total (mg/g) | Benzoic acid (BA) Total (mg/g) | Benzoic acid Total (%,W/W) | Nicotine (N) Total (mg/g) | Molar ratio | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Average | STD | CV | Average | STD | CVs | Average | Average | STD | CV | N:BA | |
| QCL | 0.0340 | 0.0009 | 2.5 | 13.03 | 0.67 | 5.2 | 1.30 | NP | — | — | NA |
| JUULTM - Fruit Medley | ND | NA | NA | 32.58 | 2.06 | 6.3 | 3.26 | 49.4 | 0.84 | 1.7 | 1.14 |
| JUULTM - Mango | 0.0283 | 0.0045 | 16.0 | 33.64 | 3.74 | 11.1 | 3.36 | 50.6 | 0.92 | 1.8 | 1.13 |
| JUULTM - Cool Mint | 0.6420 | 0.0485 | 7.6 | 33.18 | 2.84 | 8.5 | 3.32 | 49.3 | 0.75 | 1.5 | 1.12 |
| JUULTM - Virginia Tobacco | ND | NA | NA | 32.52 | 2.54 | 7.8 | 3.25 | 50.3 | 0.88 | 1.7 | 1.16 |
| JUULTM - Creme Brulee | ND | NA | NA | 32.20 | 2.62 | 8.2 | 3.22 | 50.2 | 1.08 | 2.2 | 1.17 |
| HAUSTM - Cool Ice | 0.0487 | 0.0021 | 4.3 | ND | NA | NA | ND | NP | — | — | NA |
| Pacha Mama - Mango | 0.0972 | 0.0065 | 6.7 | ND | NA | NA | ND | NP | — | — | NA |
| QCH | 0.3317 | 0.0118 | 3.6 | 29.87 | 1.27 | 4.3 | 2.99 | NP | — | — | NA |
Limits of detection (LOD), accuracy, and precision of the method_
| Analyte | LOD (ng/μL) | Accuracy (%) | % RSD intermediate precision | |||
|---|---|---|---|---|---|---|
| Low | Medium | High | QCL | QCH | ||
| Benzyl alcohol | 0.11 | 96.6 ± 1.9 | 95.4 ± 1.4 | 98.9 ± 2.3 | 5.3 | 4.4 |
| Benzoic acid | 9.05 | 92.2 ± 1.7 | 91.7 ± 4.1 | 93.8 ± 2.5 | 4.8 | 4.6 |
Results and conditions for the determination of method robustness_
| Test parameters | Analyte | Method settings | Low level settings | High level settings | |||||
|---|---|---|---|---|---|---|---|---|---|
| Method level | Amount (μg) a | Low level | Amount (μg) a | % Diff. | High level | Amount (μg) a | % Diff. | ||
| Column temperature | Benzyl alcohol | 50 °C | 3.76 ± 0.12 | 45 °C | 3.69 ± 0.13 | 1.9 | 55 °C | 3.66 ± 0.03 | 2.7 |
| 61.65 ± 0.08 | 62.90 ± 1.34 | 2.0 | 61.54 ± 0.82 | 4.7 | |||||
| Benzoic acid | 3279 ± 50 | 3241 ± 40 | 1.2 | 3171 ± 35 | 3.3 | ||||
| 3158 ± 103 | 3038 ± 84 | 3.8 | 3053 ± 55 | 3.3 | |||||
| Sample dilution composition | Benzyl alcohol | MeOH:H2O 50:50 | 2.95 ± 0.01 | MeOH:H2O 40:60 | 3.06 ± 0.06 | 3.7 | MeOH:H2O 60:40 | 2.96 ± 0.04 | 0.3 |
| 52.12 ± 4.8 | 52.21 ± 0.59 | 0.2 | 52.42 ± 1.32 | 0.6 | |||||
| Benzoic acid | 3344 ± 72 | 3324 ± 90 | 0.6 | 3415 ± 77 | 2.1 | ||||
| 2711 ± 201 | 2831 ± 111 | 4.4 | 2813 ± 60 | 3.8 | |||||
| Injection volume | Benzyl alcohol | 10 μL | 3.00 ± 0.30 | 7 μL | 3.11 ± 0.32 | 3.7 | 13 μL | 3.01 ± 0.41 | 0.3 |
| 61.26 ± 6.95 | 61.91 ± 7.09 | 1.1 | 61.17 ± 6.76 | 0.1 | |||||
| Benzoic acid | 3332 ± 396 | 3419 ± 437 | 2.6 | 3434 ± 386 | 3.1 | ||||
| 3077 ± 27 | 3137 ± 52 | 1.9 | 3147 ± 29 | 2.3 | |||||
| Sample weight | Benzyl alcohol | 100 mg | 3.03 ± 0.11 | 80 mg | 3.09 ± 0.12 | 2.0 | 130 mg | 3.05 ± 0.20 | 0.7 |
| 53.54 ± 4.25 | 53.19 ± 3.05 | 0.7 | 54.15 ± 2.25 | 1.1 | |||||
| Benzoic acid | 3360 ± 68 | 3484 ± 58 | 3.7 | 3308 ± 78 | 1.5 | ||||
| 2806 ± 210 | 2909 ± 90 | 3.7 | 2856 ± 110 | 1.8 | |||||
| Extraction time | Benzyl alcohol | 60 min | 3.01 ± 0.07 | 42 min | 2.98 ± 0.04 | 1.0 | 78 min | 2.98 ± 0.06 | 1.0 |
| 51.64 ± 4.04 | 51.75 ± 1.49 | 0.2 | 52.12 ± 0.96 | 0.9 | |||||
| Benzoic acid | 3345 ± 65 | 3293 ± 27 | 1.6 | 3327 ± 20 | 0.5 | ||||
| 2773 ± 235 | 2714 ± 21 | 2.1 | 2721 ± 23 | 1.9 | |||||
Segments used in the mass spectrometer during analysis_
| Segment | Segment time (min) | Compound | Scan type | Ions monitored (m/z) | Collision energy (eV) |
|---|---|---|---|---|---|
| 1 | 0.00 − 6.00 | NA | Full Scan | NA | |
| 2 | 6.00 − 9.50 | BOH_Q | SRM | 91.0 → 65.0 | 20.0 |
| BOH_C1 | SRM | 91.0 → 91.0 | 10.0 | ||
| BOH_C2 | SRM | 91.0 → 39.1 | 34.0 | ||
| BOH_L | SRM | 97.0 → 69.0 | 20.5 | ||
| 3 | 9.55 − 13.50 | BCOOH_Q | SRM | 123.0 → 79.0 | 10.2 |
| BCOOH_C1 | SRM | 123.0 → 77.0 | 22.1 | ||
| BCOOH_C2 | SRM | 123.0 → 105.0 | 13.6 | ||
| BCOOH_L | SRM | 129.0 → 85.0 | 10.0 | ||
| 4 | 13.55 − 20.0 | NA | Full Scan | NA |