Fig. 1
Structural formulas of molecules of steroid esters
Table 1
LC–MS/MS ion acquisition parameters (MRM mode) used for the identification and confirmation of the steroid esters
| Compound | transition (m/z) | energy CE (eV) | potential DP (V) | potential EP (V) | potential CXP (eV) | average ± SD | 5.0–50.0 μg kg−1 | CCα level |
|---|---|---|---|---|---|---|---|---|
| TP | 345.4 > 97.1* | 29 | 27 | - | - | - | ||
| 345.4 > 109.3 | 46 | 4 | 0.608 ± 0.113 | 99.2 | 100.0 | |||
| 345.4 > 253.4 | 25 | 200 | 11 | 24 | 0.272 ± 0.073 | 100.0 | 98.1 | |
| 345.4 > 271.2 | 25 | 20 | 0.322 ± 0.088 | 98.1 | 98.1 | |||
| TB | 393.3 > 97.0 | 42 | 20 | 0.435 ± 0.070 | 98.8 | 94.5 | ||
| 393.3 > 105.1 | 20 | 70 | 12 | 14 | - | - | - | |
| BU | 453.4 > 121.3 | 44 | 10 | 0.466 ± 0.065 | 97.9 | 98.1 | ||
| 453.4 > 135.1 | 26 | 16 | - | - | - | |||
| 453.4 > 149.2 | 24 | 100 | 10 | 17 | 0.414 ± 0.071 | 95.3 | 92.0 | |
| 453.4 > 269.1 | 14 | 21 | 0.814 ± 0.097 | 100.0 | 100.0 | |||
| NTD | 429.4 > 95.2 | 30 | 12 | 0.569 ± 0.114 | 99.1 | 98.0 | ||
| 429.4 > 155.1 | 26 | 27 | - | - | - | |||
| 429.4 > 239.0 | 32 | 180 | 12 | 18 | 0.319 ± 0.063 | 97.3 | 94.1 | |
| 429.4 > 257.1 | 24 | 11 | 0.833 ± 0.095 | 99.2 | 97.8 | |||
| NTPhP | 407.4 > 105.0 | 16 | - | - | - | |||
| 407.4 > 133.0 | 48 | 200 | 14 | 23 | 0.266 ± 0.073 | 97.2 | 92.5 | |
| 407.4 > 257.2 | 28 | 0.301 ± 0.070 | 98.8 | 98.2 | ||||
| T-d3P | 348.4 > 97.0 | 28 | 90 | 11 | 15 | - | - | - |
| T-d3B | 396.4 > 105.0 | 28 | 100 | 10 | 15 | - | - | - |
| T-d3D | 446.4 > 97.0 | 51 | 145 | 10 | 22 | - | - | - |
[i] * transitions shown in bold were used for quantification
TP – testosterone propionate; TB – testosterone benzoate; BU – boldenone undecylenate; NTD – nortestosterone decanoate; NTPhP – nortestosterone phenylpropionate; T-d3P – testosterone-d3 propionate; T-d3B – testosterone-d3 benzoate; T-d3D – testosterone-d3 decanoate
Table 2
Parameters of analytical efficiency of the LC-MS/MS method for the determination of steroid esters in animal hair
| Compound | TP | TB | BU | NTD | NTPhP | |
|---|---|---|---|---|---|---|
| (RSD, %) | 15 | 37.2 | 34.4 | 39.7 | 30.6 | 37.0 |
| Decision (CCα, μg limit kg−1) | 3.51 | 2.57 | 3.51 | 3.98 | 4.18 | |
| Detection (CCβ, μg capability kg−1) | 5.98 | 4.38 | 5.99 | 6.78 | 7.12 | |
| Measurement uncertainty at validation level of 10 μg kg−1 (U, k = 2, %) | 38.0 | 30.2 | 49.4 | 37.8 | 39.0 | |
| Matrix effect (%) | −5.2 | −23.6 | 22.3 | −16.9 | −18.2 | |
| Comparison of accuracy and repeatability in bovine (n = 10) and pig (n = 10) hair samples spiked at 10 μg kg−1 | ||||||
| Apparent recovery (%) | 95.2 | 109.2 | 84.6 | 101.2 | 82.5 | |
| Repeatability (RSD, %) | 19.6 | 14.1 | 22.6 | 13.1 | 16.9 | |
| t testexp. | 1.358 | 1.448 | 0.947 | 0.368 | 1.239 | |
| F testexp. | 1.915 | 0.925 | 0.487 | 2.721 | 2.787 | |
| Standard curve Slope ± sb | 0.0116 ± 0.0001 | 0.0245 ± 0.0032 | 0.2404 ± 0.0103 | 0.0171 ± 0.0038 | 0.0308 ± 0.0005 | |
| y-Intercept ± sa | −0.0009 ± 0.0021 | 0.0408 ± 0.0182 | −0.1264 ± 0.2725 | −0.0073 ± 0.0173 | 0.0059 ± 0.0301 | |
| Correlation coefficient | 0.9996 | 0.9983 | 0.9965 | 0.9873 | 0.9990 | |
| Standard error | 0.0062 | 0.0264 | 0.3919 | 0.0536 | 0.0255 | |
| Matrix matched calibration | ||||||
| curve | ||||||
| Slope ± sb | 0.0110 ± 0.0004 −0.0080 ± 0.0236 | 0.0187 ± 0.0020 0.0693 ± 0.1065 | 0.2939 ± 0.1603 −0.1453 ± 1.1592 | 0.0142 ± 0.0327 0.0728 ± 0.6266 | 0.0252 ± 0.0048 0.0642 ± 0.0682 | |
| sa y–Intercept ± | 0.9961 | 0.9943 | 0.9928 | 0.9812 | 0.9812 | |
| Correlation coefficient Standard error | 0.0187 | 0.0389 | 0.6812 | 0.0536 | 0.0947 | |
[i] * spiking level (μg kg-1), 1.734 – the value of t testcrit. (eighteen degrees of freedom), 3.178 – the value of F testcrit. (nine degrees of freedom) RSD – relative standard deviation
Fig. 2
LC–MS/MS MRM chromatograms of steroid esters (testosterone propionate, nortestosterone phenylpropionate, testosterone benzoate, boldenone undecylenate, and nortestosterone decanoate) in bovine hair samples spiked at 10 μg kg−1
Fig. 3
LC–MS/MS MRM chromatograms of steroid esters in a blank bovine hair sample in which no testosterone propionate, nortestosterone phenylpropionate, testosterone benzoate, boldenone undecylenate, or nortestosterone decanoate were found in official monitoring studies