Gemini rp 18 column
Manufactured by Phenomenex
Sourced in United States
The Gemini RP-18 column is a high-performance liquid chromatography (HPLC) column designed for the separation and analysis of a wide range of organic compounds. It features a C18 stationary phase on a silica support, which is suitable for the reversed-phase chromatography of both polar and non-polar analytes. The column dimensions and particle size can vary to accommodate different HPLC system requirements.
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Lab products found in correlation
Ultimate 3000 hplc system, by Phenomenex (2 mentions)
Microflex maldi tof mass spectrometer, by Bruker (2 mentions)
Spd 10a vp uv vis detector, by Shimadzu (1 mentions)
Hplc grade acn, by Carlo Erba (1 mentions)
Lc 8a hplc system, by Shimadzu (1 mentions)
Ch3oh, by Carlo Erba (1 mentions)
Precoated silica gel plate f254, by Merck Group (1 mentions)
Kieselgel 60, by Merck Group (1 mentions)
Lc 20at, by Shimadzu (1 mentions)
Spd m20a, by Shimadzu (1 mentions)
Ultrafree mc 10 000 mw, by Merck Group (1 mentions)
6 protocols using gemini rp 18 column
1
HPLC and MALDI-TOF Analysis of NLY01
2
HPLC and MALDI-TOF Analysis of NLY01
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(1) HPLC analysis . NLY01 purified by preparative RP-HPLC was analyzed by using a Dionex Ultimate 3000 HPLC system (Sunnyvale, CA, USA) with a Phenomenex Gemini RP-18 column (250 × 4.6 mm, 5 μm) at ambient temperature and a constant flow-rate of 1.0 mL/min under UV monitoring at 280 nm. The mobile phase consisted of 0.1% (trifluoracetic acid (TFA) in deionized water (eluent A) and acetonitrile (AN) containing 0.1% TFA (eluent B), and these were applied as linear gradients from 30% B to 60% B over 20 min. (2) MALDI-TOF mass spectrometry. Molecular weight of NLY01 was determined by a Bruker Daltonics Microflex MALDI-TOF mass spectrometer (Bremen, Germany) with a 337 nm nitrogen laser. Mass spectrum was obtained in the linear and positive-ion mode with an acceleration voltage of 20 kV. As a matrix solution, a saturated solution of sinapinic acid in acetonitrile:water (50:50, v:v) containing 0.1% TFA was used. Each analyte was mixed with a matrix solution at a ratio of 1:1 (analyte:matrix, v:v) and 1 μl of the analyte-matrix solution was applied and air-dried on the sample plate.
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3
HPLC-PDA Analysis of Phenolic Compounds
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The analyses were performed employing an HPLC-PDA Proeminence (Shimadzu, Tokyo, Japan) by method previously validated [5 ]. Briefly, a Gemini RP-18 column (250 × 4.6 mm i.d., 5 μm) (Phenomenex, USA) protected by a RP-18 guard column was used. The mobile phase consisted of 0.1% v/v trifluoroacetic acid (A) and methanol: TFA (99.9 : 0.1, v/v) (B) in a linear gradient program. The flow rate and temperature were kept constant at 0.9 mL/min and 23 ± 1°C, respectively, detection being performed at 325 nm. The total content was calculated by sum of individual contents, namely, chlorogenic acid (CLA), caffeic acid (CFA), unknown peaks (expressed as chlorogenic acid), and rutin (RUT). The results were expressed as μg/mL of extractive solution by mean value of three determinations using the chlorogenic acid (Fluka, batch 455159/1, Switzerland), caffeic acid (Extrasynthèse, batch 0381024, France), and rutin (Sigma, batch 128K1177, USA) as external standards.
4
Synthesis and Purification of Silibinin Derivatives
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Silibinin 1 was purchased from Sigma-Aldrich (Milano, Italy). HPLC-grade ACN and CH3OH were purchased from Carlo Erba Reagents and Sigma-Aldrich. Unless otherwise indicated, other chemicals were obtained from Sigma Aldrich. For the experimental synthesis procedures of tyrosol-based building blocks 6 –8 , see Romanucci et al. 2021 [37 (link)]. It must be noted that the experimental procedures for the synthesis of compounds 10 –12 and 13 –15 were described in detail only for the stereoisomer of silybin A (SilA, 1a ): the same reaction conditions (temperature, stoichiometric ratios, and time of reaction) were used for silybin B (SilB, 1b ) and silibinin (Sil, 1ab ) as a natural mixture. Reactions were monitored by TLC (precoated silica gel plate F254, Merck, Upper Gwynedd, PA, USA) and column chromatography: Merck Kieselgel 60 (70–230 mesh). The analysis was performed with a Shimadzu (Tokyo, Japan) LC-8A HPLC system equipped with a Shimadzu SCL-10A VP System control and Shimadzu SPD-10A VP UV-VIS Detector. HPLC purifications were carried out on a Phenomenex Gemini RP18 column (10 μm particle size, 21.20 mm × 250 mm i.d.) using a linear gradient of ACN in 0.1 M NH4Ac in H2O, pH 7.0, from 20% to 100% over 30 min at a flow rate of 8 mL/min, with detection at 288 and 260 nm. MALDI spectral data were acquired on a MALDI TOFTOF AB Sciex 5800 mass spectrometer.
5
Phytochemical Analysis of Schinus Terebinthifolius
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The chief phytochemical markers (i.e., gallic acid, ellagic acid, catechin, and epicatechin) in S. terebinthifolius samples were analyzed by liquid chromatography-diode array detection (LC-DAD) analysis using a HPLC system (LC-20AT, Shimadzu, Kyoto, Japan) equipped with a photodiode array detector (SPD-M20A, Shimadzu, Kyoto, Japan). Chromatographic separation was performed using a Gemini RP-18 column (5 µm particle size and 250 × 4.60 mm i.d.; Phenomenex, Torrance, CA, USA) protected by a guard column of the same material.
Gradient elution was performed by varying the proportion of solvent A (0.5% acetic acid in distilled water, v/v) and solvent B (methanol) at a flow rate of 0.8 mL/min following a gradient program of 20–40% B (10 min), 40–60% B (10 min), 60% B (10 min), 60–40% B (10 min), and 40–20% B (10 min). The dried extracts and standards were dissolved in methanol: water (20 : 80, v/v) and filtered through a membrane of 0.45 µm (Millipore, Billerica, MA, USA) prior to injection of 20 µL. The peaks of each marking on dry substance were identified by comparing retention times and UV spectra of DAD.
Gradient elution was performed by varying the proportion of solvent A (0.5% acetic acid in distilled water, v/v) and solvent B (methanol) at a flow rate of 0.8 mL/min following a gradient program of 20–40% B (10 min), 40–60% B (10 min), 60% B (10 min), 60–40% B (10 min), and 40–20% B (10 min). The dried extracts and standards were dissolved in methanol: water (20 : 80, v/v) and filtered through a membrane of 0.45 µm (Millipore, Billerica, MA, USA) prior to injection of 20 µL. The peaks of each marking on dry substance were identified by comparing retention times and UV spectra of DAD.
6
Quantification and Encapsulation of Diflunisal in Nanocapsules
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Loading rate was determined after dissolution of an aliquot (200 µl) of nanocapsules suspension in 10 ml of mobile phase followed by ultrasound for 10 min and quantified by liquid chromatography (LC) using a previously validated methodology [21] . The chromatographic system consisted of a Gemini RP-18 column (250 mm x 4.6 mm, 5 µm, Phenomenex Torrance, USA) and Shimadzu instrument (LC-10AVP Pump, UV-vis SDP-10AVP, Japan). The mobile phase (at a flow rate of 1.0 ml/min) was composed of acetonitrile/water (80:20%, v/v), the volume of injection was 20 µl, and DFZ was detected at 244 nm. The method was linear (r² = 0.9999) in the range of 5-40 µg/ml, accurate (recovery: 95.75 ± 0.5 %), and precise (R.S.D.: < 1.41% for repeatability and < 2.37 for intermediate precision). Specificity was tested in the presence of the suspension adjuvants, when these factors were shown not to alter the DFZ assay.
The encapsulation efficiency (%) was determined by the difference between total drug (loading rate) and free DFZ concentration. Free DFZ (non-associated to nanostructures) was determined in the ultrafiltrate after separation of the nanoparticles by ultrafiltration/centrifugation (Ultrafree-MC10.000 MW, Millipore, UDA), at 1000 rcf for 10 min. All analysis were performed in triplicate.
The encapsulation efficiency (%) was determined by the difference between total drug (loading rate) and free DFZ concentration. Free DFZ (non-associated to nanostructures) was determined in the ultrafiltrate after separation of the nanoparticles by ultrafiltration/centrifugation (Ultrafree-MC10.000 MW, Millipore, UDA), at 1000 rcf for 10 min. All analysis were performed in triplicate.
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