Sciex 4500 qtrap mass spectrometer

The LC instrumentation was an LC-20AD chromatograph (Shimadzu, Kyoto, Japan), and the tandem mass spectrometer was an AB SCIEX 4500 QTRAP mass spectrometer. We conducted the chromatographic separation of steroids on a Kinetex™ 2.6 μm PFP 100 Å column (100 × 3 mm) with a flow rate of 0.3 ml/min. The column temperature was set to 45°C, and the injection volume was 20 μl. Mobile phases were purified water (A) and methanol (B). The gradient elution was summarized as follows: 0–2 min, 60% B; 2–13.9 min, 60% to 100% B; 13.9–14.0 min, 60% B; and 14–21 min, 60% B. The total analysis required 21 min, and more polar compounds were diverted to waste for the first 6.8 min to keep the mass spectrometer clean.
The mass spectrometer was operated in positive mode using an ESI source. The analytes were monitored by multiple reaction monitoring, and optimized quantitative mass transitions are listed in Table 1. In addition, positive ESI mass spectra of derivatized steroids are shown in supplemental Figs. S1–S3). The cleavages and fragments of analytes are shown in supplemental Table S2. Data acquisition and processing were conducted using AB SCIEX Analyst version 1.6.2.

A validated and ELAP-accredited method that was developed in the NYSDOH Medical Marijuana Laboratory for the quantitation of aflatoxins B1, B2, G1, G2, and ochratoxin A in medical marijuana products was used [8 ]. The method employs LC-MS/MS on a Shimadzu HPLC system consisting of a SIL-20ACxR autosampler, an FCV-11A2 solvent selector and LC-20ADxR pumps interfaced with an AB Sciex 4500 QTRAP mass spectrometer operating in the positive-ion ESI mode. Analytes were detected using scheduled MRM with two MS/MS transitions (quantifier and qualifier) for each analyte and ¹³C-labeled internal standard. The method calls for the extraction of 100 mg of material; however, due to the limited amounts of sample material available in this project, a scaled-down sample extraction method was used to prepare the samples. Details of this analytical method are available [8 ].

Plasma levels of teicoplanin were quantified using tandem mass spectrometry coupled with HPLC (HPLC-MS/MS). The analytical system utilized included an LC-40 HPLC unit from Shimadzu Co. (Kyoto, Japan) paired with a Gemini C18 analytical column from Phenomenex (Torrance, CA, USA). A SCIEX 4500 QTRAP mass spectrometer (Sciex, Redwood City, CA, USA) facilitated the MS-based detection. Calibration standards were prepared by combining 100 μL of a reference solution with 10 μL of a vancomycin internal standard (concentration of 100 μg/mL) in microcentrifuge tubes. To this mixture, 400 μL of acetonitrile was added to precipitate proteins, followed by vortex mixing for 60 s. Following centrifugation at 12,000 rpm for 2 min at 4 °C, the clear supernatant was diluted 10-fold with deionized water. A 10 μL sample of this solution was then introduced into the HPLC-MS/MS for analysis. In a parallel procedure for plasma samples, after the addition of the vancomycin internal standard and acetonitrile-induced protein precipitation, the sample was processed like that of the calibration standard preparation before HPLC-MS/MS analysis. The teicoplanin concentration in the plasma was determined by comparing the peak area ratio of teicoplanin to the internal standard and employed a batch-specific calibration curve equation, adjusted for 1/x² weighting.