Organic acids capillary columns

Different capillary columns are available for organic acid separation and analysis. In our laboratory, the gas chromatography column in all GC-MS applications is crosslinked 5% phenyl (poly)methyl silicone, 25 m internal diameter 0.20 mm stationary phase film thickness 0.33 pm (Agilent HP-5, DB-5, or equivalent). Several instrument configurations are commercially available, which allow for positive identification of compounds by their mass spectra obtained in the electron impact ionization mode. A commercially available bench-top GC-MS system with autosampler (Agilent 6890/5973, or equivalent) is suitable. Software for data analysis is available and recommended. The use of a computer library of mass spectra for comparison and visualization of the printed spectra is required for definitive identification and interpretation of each patient specimen. 

A GS-MS method for the analysis of etodolac in human plasma has been developed [16]. Plasma samples were spiked with meclofenamic acid (the internal standard), acidified with 5N HC1, and extracted twice with chloroform / dichloromethane / hexane (50 25 25, v/v). The organic phase was evaporated, the residue methylated with ethereal diazomethane, dried again, and reconstituted in hexane. Analytical separation was performed on a 15 m x 0.24 mm i.d., 0.25 pm film thickness, fused silica capillary column. The oven temperature was variable (150 to 260°C) and the injector was at 260°C. The carrier gas was helium at 1 mL/min. Mass spectra were obtained using positive electron impact ionization (70 eV) at m/z 228 for etodolac. The method was linear in the 1-10 ng/mL (low) and 10-100 ng/mL (high) concentration range. The detection limit was 0.5 ng/mL in plasma, and recovery of etodolac from plasma sample exceeded 92%. 

Acid, base and neutral organics — Capillary column — Combination of -robotics with capillary GC-MS [198]... 

Figure 1.13 GC analysis of organic acid methyl esters in a) standard solution, b) Chardonnay wine, c) Asti sparkling wine. 1. methyl lactate, 2. dimethyl succinate, 3. dimethyl maleate (i.s.), 4. dimethyl malate, 5. dimethyl tartrate, 6. trimethyl citrate. Chromatographic conditions poly(ethylene) glycol fused silica capillary column (30m x 0,25mm 0.25 xm), injector and detector temperature 250°C, flame ionization detector. Oven program 2min at 50 °C, from 50 to 200 °C at rate 4°C/min, 200°C isotherm for lOmin (Di Stefano and Bruno, 1983)...

Capillary gas chromatography-mass spectrometry is being used to separate and measure the trimethylsilyl (TMS) ethers of organic acids. A capfilary GC column is used that contains an immobilized nonpolar stationary phase. Organic acids are detected by electron impact (El) mass spectrometry performed in the scan mode m/z 50 to m/z 550 to obtain mass spectra. Identification is by comparison to a library of spectra generated by analysis of pure standard compounds integrated by published spectra, when applicable. 

LPS samples (0.5 mg) were hydrolyzed with 2 mol l-1 TFA at 100 °C for 18 h followed by reduction in dH20 with NaBH4 and subsequent acetylation with acetic acid/pyridine (1 1, v/v) at 100 °C for 1 h. The resultant alditol acetates were extracted thrice with dichloromethane, the combined organic layer concentrated to dryness and analyzed by GLC using a Hewlett-Packard chromatograph equipped with a 30 m DB-17 capillary column (190 °C (32 min), 16 °C min-1 to 270 °C (32 min)) and by GLC-MS in the electron impact mode (El) recorded using a Varian Saturn 2000 mass spectrometer. For compositional analysis of acid-labile deoxy... 

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