0000000000345165
AUTHOR
Ulrich Fauth
Determination of α-Tocopherol in Plasma by High Performance Liquid Chromatography with Fluorescence Detection and Stability of α-Tocopherol under Different Conditions
In order to study the clinical effects of the antioxidant alpha-tocopherol (tocofersolan, CAS 30999-06-5) a simple, robust, sensitive and reliable high performance liquid chromatography (HPLC) method using fluorescence detection for the daily measurement of alpha-tocopherol concentration in plasma is described. Several methods of HPLC analysis using fluorescence techniques are published, however, investigations of the stability of alpha-tocopherol during sample preparation under different conditions are relevant in the routine measurements and have to date not been reported. Therefore a modified method, both sensitive and robust, qualified for the day-by-day measurement of alpha-tocopherol …
Metabolic Clearance of the Antioxidant Ascorbic Acid in Surgical Patients1
Background A reduction of plasma ascorbic acid concentration in the post-operative period has been well documented and is associated with an increase in post-operative complications. The underlying reason for the decreased concentration of ascorbic acid in the plasma is not clear. However, only an increased post-operative requirement for ascorbic acid would justify a substitution. Therefore, we investigated the pre-operative and post-operative metabolic clearance of ascorbic acid. Materials and Methods We calculated the metabolic clearance subsequent to intravenous bolus injection of 6 mg ascorbic acid/kg body weight in 15 patients before and after they underwent major maxillofacial surgery…
The Measurement of Enzyme Activities in the Resting Human Polymorphonuclear Leukocyte — Critical Estimate of a Method
As a system for study, the isolated human polymorphonuclear leukocyte combines the advantages of a quasi-non-invasive preparation with a nearly complete complement of enzymes of carbohydrate and energy metabolism. However, small sample volumes and, in some cases, very low enzyme activities make high demands on sample processing, storage, and performance of continuous measurements, if the enzyme activities are to be measured with acceptable reproducibility. In the presented study several aspects of homogenization, storage, and continuous measurement were scrutinized, to identify critical steps and consider ways of optimizing the method. Polymorphonuclear leukocytes were separated from the bl…
Ceftazidime Determination in Serum by High-pressure Liquid Chromatography
A rapid and sensitive high-pressure liquid chromatographic method with simple sample preparation was developed for the quantitative analysis of the beta-lactam antibiotic ceftazidime (CAS 78439-06-2, Fortum). A good linear relationship was established between the peak area and the amount of ceftazidime injected over a concentration range of 1 to 200 microg/ml. The detection limit of the method was calculated to be 0.9 microg/ml. Stability was shown at 4 degrees C and at -196 degrees C for time periods of 2 h and 84 days, respectively.
Determination of ascorbic acid in plasma and urine by high performance liquid chromatography with ultraviolet detection.
Abstract A reliable simple reversed-phase liquid chromatographic method for the routine determination of ascorbic acid in plasma and urine with ultraviolet detection is described. This method enables the complete separation of the ascorbic acid peak from others with a recovery of above 95 % within 8 minutes. The method can be used for analysing multiple samples within a day. In addition, the storage conditions and stability of ascorbic acid in plasma and urine were investigated. Samples of plasma and urine can be stored on ice in darkness for at least 60 min without reduction of ascorbic acid concentration. Prepared samples can be stored in darkness at 4 °C for at least 120 min and in liqui…
Clearance of Ascorbic Acid in Plasma in Patients Before Major Maxillofacial Surgery Compared With That in Volunteers
Reduced concentration of ascorbic acid (AA) in plasma is often observed in tumor patients. Besides malnutrition, an increased AA consumption in tumor patients is discussed as a main reason for reduced AA concentration in plasma. A reduced AA concentration caused by malnutrition would not influence the total clearance (Cltot) of AA in plasma; however, a change in AA consumption would alter the Cltot. To investigate this further, a study was carried out on 20 patients hospitalized for major maxillofacial surgery and 20 volunteers. The Cltot of AA in plasma after bolus injection of AA (4 mg/kg body wt) in tumor patients was compared with that in volunteers. AA concentration in plasma (P0.05) w…