Claudio. Borra

Quantitative analytical aspects of reversed-phase liquid chromatography with slurry-packed capillary columns

Conditions for reproducible packing of fused-silica liquid chromatography capillary columns were demonstrated. The plate height vs. velocity curves were determined for successively prepared columns. In addition, the values of separation impedance were calculated. Several liquid chromatography systems were evaluated in conjunction with the slurry-packed capillaries for the retention and peak area reproducibility.

Reliable measurement of non-esterified long-chain fatty acid pattern in blood plasma.

In this reliable assay for determining the non-esterified long-chain fatty acid pattern in plasma, only 100 microliters of sample are needed and a single assay can be done within 40 min. The isolation procedure was performed by adsorption of fatty acids from plasma onto graphitized carbon black (Carbopack B) using a column method. After desorption and removal of the eluting phase, fatty acids are methylated by diazomethane and quantified by packed column gas chromatography. Analytical recoveries ranged between 91% and 103%. Within-run precision gave coefficients of variation of 2.3% and 11% for fatty acid concentrations of 58.2 and 0.6 mumol/l, respectively. Studies of plasma samples under various storage conditions indicated that reliable measurement of the non-esterified fatty acid fraction can be obtained even after 60 days if specimens are conserved at -18 degrees C in the presence of a suitable phospholipase inhibitor.