Graphitized Carbon Liquid Chromatography Research Articles

Protein glycosylation analysis by liquid chromatography–mass spectrometry

Liquid chromatography (LC)-mass spectrometry (MS) has developed into an invaluable technology for the analysis of protein glycosylation. This review focuses on the recent developments in LC and combinations thereof with MS for this field of research. Recently introduced methods for the structural analysis of released glycans (native or derivatised) as well as glycopeptides, on normal phase, reverse phase and graphitized carbon LC columns with online MS(/MS) will be reviewed. Performed on nano-scale or capillary-scale, these LC-MS methods operate at femtomole sensitivity and support the further integration of glycosylation analysis in proteomics methodology.

Determination of isoprostanes in urine samples from Alzheimer patients using porous graphitic carbon liquid chromatography–tandem mass spectrometry

F2-isoprostanes (F2-iPs) comprise four classes of isomers produced non-enzymatically by free radical attack on arachidonic acid, a component of the cell membrane. This paper describes a new method for the quantification of F2-isoprostanes in urine samples from thoroughly diagnosed Alzheimer’s disease (AD) patients. The sample pretreatment consisted of liquid extraction of 900 μl urine with diethyl ether, its subsequent evaporation, and finally, reconstitution in 50 μl water. Of this, 20 μl was injected into a HPLC system with a 15 mm×1 mm porous graphitic carbon column coupled to a triple quadrupole mass spectrometer running in negative electrospray ionization mode. The F2-isoprostanes were separated in 15 min using a linear solvent gradient comprising water, methanol, acetonitrile and ammonium hydroxide at a pH of 9.5. The average recovery obtained was approximately 75%. The limit of detection (3S/N) was calculated for iPF2α-III to be 0.7 pg injected on column, corresponding to 0.1 nM. The average level of iPF2α was 241±163 pg/mg creatinine in the urine samples from AD patients (average±standard deviation). The corresponding control values were 216±101 pg/mg creatinine, i.e. no statistically significant difference was noticed. No correlation pattern specific to Alzheimer’s disease was revealed by principal component analysis of the isoprostane peaks obtained either. The results from this study support earlier findings that levels of peripheral isoprostanes are not increased in patients with Alzheimer’s disease.

A selective method for the determination of benzo[a]pyrene in soil using porous graphitic carbon liquid chromatography columns

A back-flushing procedure using porous graphitic carbon (PGC) HPLC columns has been used successfully for the cleanup of soil samples for the determination of benzo[a]pyrene in ppb levels by an ODS-fluorescence HPLC column. The procedure was tested on nine random soil samples taken from an industrial area of the Kingdom of Bahrain. The mean percent recovery from the PGC column was 96% and the average coefficient of variation for the whole method was 5.2%.