Hp 5 quartz capillary column

Compounds 3 and 4 (each 2.0 mg) were hydrolyzed in 2 M HCl (3 mL) at 65 °C for 4 h, respectively. The reaction mixture was extracted with CH₂Cl₂, three times (3 × 3 mL). The aqueous layer was neutralized with 2 M NaOH and dried to produce a monosaccharide mixture. Next, l-cysteine methyl ester hydrochloride (1.0 mg) was added to a no aqueous pyridine solution of the sugar mixture (1.0 mL) and kept at 60 °C for 1 h. After this, trimethylsilylimidazole (1.0 mL) was added to the reaction mixture and kept at 60 °C for 30 min, followed the extraction with n-hexane (1 × 2 mL). The n-hexane layer was subjected to GC analysis, run on a Agilent Technologies HP5890 gas chromatograph, equipped with a HP-5 quartz capillary column (30 mm × 0.32 mm × 0.25 mm) and a H₂ flame ionization detector with the following conditions: column temperature, 180–280 °C; programmed increase, 3 °C/min; carrier gas, N₂ (1.5 mL/min); injector and detector temperature, 250 °C; injection volume, 2.0 μL; and split ratio 1/50. The configuration of the sugar moiety was determined by comparing the retention time with the derivatives of the authentic samples. The retention times of d-/l-glucose were 20.418/20.825 min, and the configuration of the respective sugar moiety from compounds 3 and 4 was determined as d-glucose.

Before the Gas Chromatography-Mass Spectrometer (GC–MS) characterization, the silanization of LP was necessary to reduce its high boiling point. First, the LP was extracted three times with methylene chloride. The extracted liquid was blow-dried with nitrogen. Then, then 80 μL pyridine and 150 μL BSTFA+TMCS were added into the extracted liquid for silanization at 70 °C for 45 min. Subsequently, the sample was filtered using a microporous filtration membrane of 0.22 μm and then used for the measurement [29 (link)]. The compositions of silanized LP were analyzed by GC–MS of 7990B-7000C (Agilent Technologies, Santa Clara, CA, USA) with HP-5 quartz capillary column (30 m × 0.25 mm × 0.25 μm).

A gas chromatography (GC) method was employed to identify cholesterol synthesis (squalene, lathosterol, and desmosterol) and absorption markers (campesterol, stigmasterol, and sitosterol). The serum was assayed by saponification with an alkaline alcohol solution, extraction with hexane, and silylation. The detection conditions included (1) an HP-5 quartz capillary column with an initial column temperature of 150°C, maintained for 3 min, and a programmed ramp rate of 30°C/min to 250°C; (2) a further ramp to 280°C at 5°C/min, maintained for 30 min; (3) a hydrogen flame ionization detector (FID) with an inlet temperature of 290°C and a pressure of 15 psi; and a nonsplit mode with a sample injection of 1 μL. An Agilent 7890 gas chromatograph was used for image acquisition [6 (link)]. The markers were determined by the single internal standard curve method. As noncholesterol sterols are transported in the plasma by lipoproteins, it is common to adjust them for the total plasma cholesterol level by expressing noncholesterol sterols as a ratio to the cholesterol level (noncholesterol sterol/cholesterol).