Chinese Journal of Chromatography ›› 2023, Vol. 41 ›› Issue (9): 771-780.DOI: 10.3724/SP.J.1123.2023.03009
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SHI Hongfei1,*(), XU Bopeng1, XU Chengxin1, ZHOU Xiuqi1, XU Hongfu2
Received:
2023-03-13
Online:
2023-09-08
Published:
2023-09-15
Supported by:
CLC Number:
SHI Hongfei, XU Bopeng, XU Chengxin, ZHOU Xiuqi, XU Hongfu. Rapid extraction and detection of five alkaloids in dried khat by solvent extraction-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry[J]. Chinese Journal of Chromatography, 2023, 41(9): 771-780.
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URL: https://www.chrom-china.com/EN/10.3724/SP.J.1123.2023.03009
Compound | Retention time/min | Precursor ion (m/z) | Fragment ion (m/z) | Fragmentor/V | CE/eV |
---|---|---|---|---|---|
Norephedrine | 5.32 | 152.1070 | 134.0964* | 130 | 10 |
117.0699 | |||||
Norpseudoephedrine | 5.77 | 152.1070 | 134.0964* | 130 | 10 |
117.0699 | |||||
Cathinone | 6.00 | 150.0913 | 117.0573* | 140 | 26 |
105.0699 | |||||
Methcathinone | 6.41 | 164.1070 | 146.0964* | 140 | 10 |
131.0730 | |||||
Ethcathinone | 6.75 | 178.1226 | 160.1121* | 160 | 10 |
132.0808 |
Table 1 Retention times, precursor ions, fragment ions, fragmentor, collision energies (CEs) for the five alkaloids
Compound | Retention time/min | Precursor ion (m/z) | Fragment ion (m/z) | Fragmentor/V | CE/eV |
---|---|---|---|---|---|
Norephedrine | 5.32 | 152.1070 | 134.0964* | 130 | 10 |
117.0699 | |||||
Norpseudoephedrine | 5.77 | 152.1070 | 134.0964* | 130 | 10 |
117.0699 | |||||
Cathinone | 6.00 | 150.0913 | 117.0573* | 140 | 26 |
105.0699 | |||||
Methcathinone | 6.41 | 164.1070 | 146.0964* | 140 | 10 |
131.0730 | |||||
Ethcathinone | 6.75 | 178.1226 | 160.1121* | 160 | 10 |
132.0808 |
Fig. 1 Extracted ion chromatograms (EIC) of the five alkaloids using the three columns Peak identifications: 1. norephedrine; 2. norpseudoephedrine; 3. cathinone; 4. methcathinone; 5. ethcathinone.
Fig. 4 Extracted ion chromatogram of characteristic ion pair (150.0913/117.0573) of cathinone and secondary mass spectra of cathinone and two cathinone analogues with collision energy 25 eV in khat sample before purify 1. cathinone; 2,3. other configuration.
Fig. 6 Extracted ion chromatograms of the five alkaloids in the purified khat sample Characteristic ion pairs: a. 152.1070/134.0964 for norephedrine and norpseudoephedrine, 150.0913/117.0573 for cathinone; b. 164.107/146.0964 for methcathinone, 178.1226/160.1121 for ethcathinone. Peak identifications: 1. norephedrine; 2. norpseudoephedrine; 3. cathinone; 4. methcathinone; 5. ethcathinone.
Compound | Regression equation | Linear range/(μg/L) | r2 | LOD/(μg/L) | LOQ/(μg/L) |
---|---|---|---|---|---|
Norephedrine | y=4.71×103x+2.74×104 | 10-150 | 0.9976 | 0.75 | 2.50 |
Norpseudoephedrine | y=3.18×103x+1.96×104 | 10-150 | 0.9978 | 0.75 | 2.50 |
Cathinone | y=3.34×103x+2.09×104 | 10-150 | 0.9995 | 0.34 | 1.16 |
Methcathinone | y=1.56×104x+1.96×102 | 1-25 | 0.9994 | 0.08 | 0.25 |
Ethcathinone | y=9.15×103x-1.53×102 | 1-25 | 0.9992 | 0.17 | 0.55 |
Table 2 Linear regression equations, linear ranges, correlation coefficients (r2), LODs and LOQs of the five alkaloids
Compound | Regression equation | Linear range/(μg/L) | r2 | LOD/(μg/L) | LOQ/(μg/L) |
---|---|---|---|---|---|
Norephedrine | y=4.71×103x+2.74×104 | 10-150 | 0.9976 | 0.75 | 2.50 |
Norpseudoephedrine | y=3.18×103x+1.96×104 | 10-150 | 0.9978 | 0.75 | 2.50 |
Cathinone | y=3.34×103x+2.09×104 | 10-150 | 0.9995 | 0.34 | 1.16 |
Methcathinone | y=1.56×104x+1.96×102 | 1-25 | 0.9994 | 0.08 | 0.25 |
Ethcathinone | y=9.15×103x-1.53×102 | 1-25 | 0.9992 | 0.17 | 0.55 |
Compound | Sample A | Sample B | |||||||
---|---|---|---|---|---|---|---|---|---|
Background/ (mg/kg) | Added/ (mg/kg) | Recovery/ % | RSD/ % | Background/ (mg/kg) | Added/ (mg/kg) | Recovery/ % | RSD/ % | ||
Norephedrine | 46.4 | 20.0 | 105.2 | 2.9 | 73.8 | 20.0 | 96.7 | 1.8 | |
Norpseudoephedrine | 1578.5 | 300.0 | 98.7 | 1.4 | 1716.8 | 500.0 | 102.2 | 2.0 | |
Cathinone | 266.3 | 200.0 | 103.2 | 2.0 | 40.2 | 30.0 | 92.8 | 1.1 | |
Methcathinone | 0.6 | 0.8 | 97.0 | 0.3 | 0.1 | 0.2 | 90.7 | 0.9 | |
Ethcathinone | 0.3 | 0.4 | 99.3 | 1.0 | 0.1 | 0.2 | 91.6 | 0.4 |
Table 3 Recoveries and their relative standard deviations (RSDs) of the five alkaloids spiked in two khat samples (n=6)
Compound | Sample A | Sample B | |||||||
---|---|---|---|---|---|---|---|---|---|
Background/ (mg/kg) | Added/ (mg/kg) | Recovery/ % | RSD/ % | Background/ (mg/kg) | Added/ (mg/kg) | Recovery/ % | RSD/ % | ||
Norephedrine | 46.4 | 20.0 | 105.2 | 2.9 | 73.8 | 20.0 | 96.7 | 1.8 | |
Norpseudoephedrine | 1578.5 | 300.0 | 98.7 | 1.4 | 1716.8 | 500.0 | 102.2 | 2.0 | |
Cathinone | 266.3 | 200.0 | 103.2 | 2.0 | 40.2 | 30.0 | 92.8 | 1.1 | |
Methcathinone | 0.6 | 0.8 | 97.0 | 0.3 | 0.1 | 0.2 | 90.7 | 0.9 | |
Ethcathinone | 0.3 | 0.4 | 99.3 | 1.0 | 0.1 | 0.2 | 91.6 | 0.4 |
Compound | Contents in sample A/(mg/kg) (RSD/%) | Contents in sample B/(mg/kg) (RSD/%) | |||||
---|---|---|---|---|---|---|---|
Intra-sample (n=6) | Intra-day (n=6) | Inter-day (n=6) | Intra-sample (n=6) | Intra-day (n=6) | Inter-day (n=6) | ||
Norephedrine | 47.9 (2.3) | 47.6 (2.4) | 45.2 (3.2) | 75.9 (2.2) | 75.2 (2.5) | 76.8 (3.3) | |
Norpseudoephedrine | 1575.3 (1.5) | 1589.3 (2.0) | 1588.2 (1.9) | 1719.2 (2.3) | 1721.4 (2.4) | 1720.4 (2.3) | |
Cathinone | 267.2 (1.8) | 264.5 (1.0) | 269.8 (2.2) | 40.5 (0.7) | 40.9 (1.6) | 39.6 (1.9) | |
Methcathinone | 0.6 (0.6) | 0.6 (1.5) | 0.6 (2.0) | 0.1 (1.4) | 0.1 (1.5) | 0.1 (2.4) | |
Ethcathinone | 0.3 (0.9) | 0.3 (1.0) | 0.3 (1.3) | 0.1 (0.5) | 0.1 (1.5) | 0.1 (1.7) |
Table 4 Contents and instrument, intra-day, inter-day RSDs of the five alkaloids in two khat samples
Compound | Contents in sample A/(mg/kg) (RSD/%) | Contents in sample B/(mg/kg) (RSD/%) | |||||
---|---|---|---|---|---|---|---|
Intra-sample (n=6) | Intra-day (n=6) | Inter-day (n=6) | Intra-sample (n=6) | Intra-day (n=6) | Inter-day (n=6) | ||
Norephedrine | 47.9 (2.3) | 47.6 (2.4) | 45.2 (3.2) | 75.9 (2.2) | 75.2 (2.5) | 76.8 (3.3) | |
Norpseudoephedrine | 1575.3 (1.5) | 1589.3 (2.0) | 1588.2 (1.9) | 1719.2 (2.3) | 1721.4 (2.4) | 1720.4 (2.3) | |
Cathinone | 267.2 (1.8) | 264.5 (1.0) | 269.8 (2.2) | 40.5 (0.7) | 40.9 (1.6) | 39.6 (1.9) | |
Methcathinone | 0.6 (0.6) | 0.6 (1.5) | 0.6 (2.0) | 0.1 (1.4) | 0.1 (1.5) | 0.1 (2.4) | |
Ethcathinone | 0.3 (0.9) | 0.3 (1.0) | 0.3 (1.3) | 0.1 (0.5) | 0.1 (1.5) | 0.1 (1.7) |
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