The standard of ligandrol (LGD-4033) was purchased from Toronto Research Chemicals; TRC (Toronto, ON, Canada). Stock solution of standard substance was prepared at the concentration of 1 mg/mL and its working solutions (100 µg/mL, 10 µg/mL, and 1 µg/mL) in methanol and stored at −20 °C.
Due to unavailability of certified reference materials of LGD-4033 metabolites, the reference urine collected from volunteers who ingested 50 µg of LGD-4033 dissolved in 120 mL of drinkable yogurt was utilized in the experiment [14 (link)].
LC/MS-grade of methanol and acetonitrile were purchased from MerckMillipore (Darmstadt, Germany) and Fisher Chemical (Hampton, NH, USA), respectively. Disodium phosphate and monosodium phosphate ≥ 99% purity were supplied by Honeywell (Charlotte, NC, USA), while potassium carbonate and potassium bicarbonate, both HPLC grade, were purchased at POCH S.A. (Gliwice, Poland). In turn, β-glucuronidase (Escherichia coli) and HPLC-grade methyl tert-butyl ether were supplied by Roche (Basel, Switzerland) and J.T.Baker (Philipsburg, NJ, USA), respectively. The Millipore DirectQ UV3 system (Darmstadt, Germany) was used as the source of water (R > 18 MΩ/cm). Sample preparation of dietary supplement samples followed the protocol described in [19 (link),20 (link)].
Due to unavailability of certified reference materials of LGD-4033 metabolites, the reference urine collected from volunteers who ingested 50 µg of LGD-4033 dissolved in 120 mL of drinkable yogurt was utilized in the experiment [14 (link)].
LC/MS-grade of methanol and acetonitrile were purchased from MerckMillipore (Darmstadt, Germany) and Fisher Chemical (Hampton, NH, USA), respectively. Disodium phosphate and monosodium phosphate ≥ 99% purity were supplied by Honeywell (Charlotte, NC, USA), while potassium carbonate and potassium bicarbonate, both HPLC grade, were purchased at POCH S.A. (Gliwice, Poland). In turn, β-glucuronidase (Escherichia coli) and HPLC-grade methyl tert-butyl ether were supplied by Roche (Basel, Switzerland) and J.T.Baker (Philipsburg, NJ, USA), respectively. The Millipore DirectQ UV3 system (Darmstadt, Germany) was used as the source of water (R > 18 MΩ/cm). Sample preparation of dietary supplement samples followed the protocol described in [19 (link),20 (link)].
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