Specific detection of acetyl-coenzyme A by reversed-phase ion-pair high-performance liquid chromatography with an immobilized enzyme reactor

Quantification of the concentration and 13C tracer enrichment of long-chain fatty acyl-coenzyme A in muscle by liquid chromatography/mass spectrometry

Recent diabetes and obesity research has been focused on the role of intracellular lipids in insulin resistance. Fatty acyl-coenzyme A (CoA) esters play a central role in the trafficking of intracellular lipids, but there has not previously been a method with which to quantify their kinetics using tracer methodology. We have therefore developed a high-performance liquid chromatography (HPLC)-mass spectrometry method to simultaneously measure the (13)C stable isotopic enrichment of palmitoyl-acyl-CoA ester and the concentrations of five individual long-chain fatty acyl-CoA esters extracted from muscle tissue samples. The long-chain fatty acyl-CoA can be effectively extracted from frozen muscle tissue samples and baseline separated by a reverse-phase HPLC with the presence of a volatile reagent-triethylamine. Negative ion electrospray mass spectrometry with selected ion monitoring was used to analyze the fatty acyl-CoAs to achieve reliable quantification of their concentrations and (13)C isotopic enrichment. Applying this protocol to rabbit muscle samples demonstrates that it is a sensitive, accurate, and precise method for the quantification of long-chain fatty acyl-CoA concentrations and enrichment.

Derivatization of thiol-containing compounds

The determination of thiol-containing compounds in biological fluids is important in biochemistry and clinical chemistry. In this paper, derivatization reagents for thiols are reviewed with respect to their reactivity, selectivity, spectroscopic characteristics and their applicability especially to high-performance liquid chromatography. Derivatization used in ultraviolet and electrochemical detection. The derivatization reagents contain a functional group, e.g. an N-substituted maleimide, active halogen or aziridine, which react with the thiol group. Derivatization for use in flow injection analysis, thin-layer chromatography or gas chromatography-mass spectrometry is also described.

Amperometric determination of oxalate in plasma and urine by liquid chromatography with immobilized oxalate oxidase

A detection system for plasma and urinary oxalate involving a postcolumn enzymatic reaction and electrochemical detection is described. Oxalate oxidase was immobilized on AF-Tresyl Toyopearl 650 gel. The immobilized oxalate oxidase was packed into a stainless-steel column (10 x 4 mm I.D.) and used on-line as an immobilized enzyme reactor (IMER). The hydrogen peroxide produced by enzymatic reaction was detected amperometrically at a platinum electrode maintained at +0.5 V vs. Ag/AgCl. The HPLC separation of oxalate was carried out using a Capcell Pak C8 column and an isocratic mobile phase containing 80 mM KH2PO4 and 5 mM tetra-n-butylmammonium phosphate as an ion-pair reagent. The IMER was active and stable in the mobile phase employed. The plot of peak height against concentration of oxalate was linear in the range 0.1-1.6 mumol/ml with a correlation coefficient of 0.9989. The detection limit was 10 nmol/ml at a signal-to-noise ratio of 3. The within-day and between-day coefficients of variation were 5.3 and 7.9%, respectively.