A comparison of methods, two based upon 5-hydroxymethylfurfural determination (colorimetric using a semi-automated procedure and HPLC) and ion exchange chromatography (HbA1 using BioRad method) was performed. The influence of variables on 5-hydroxymethylfurfural determination is reported. The dialysis step appears to be essential for an accurate determination of 5-hydroxymethylfurfural released...

In this paper, an ultrasound±acetic acid procedure for the simultaneous extraction and hydrolysis of carbohydrates in marine sediments prior to their colorimetric determination is described. The main advantage of the proposed procedure is the improved analytical accuracy achieved. Extraction and hydrolysis are quantitative since the oxidative reactions which cause the underestimation of the tot...

Salicylate concentrations in 3819 sera of apparently healthy voluntary blood donors were determined in view of the significance of this drug in the induction of allergic reactions and its possible interference in platelet function. Two hundred and ninety-five sera were found by a modified colorimetric determination to contain salicylates. The colorimetric determination was compared with a high ...

A method for the determination of nitrogen in ruminant feedstuffs, products and excreta (e.g. milk and urine) using a spectrophotometer is developed, where samples processed for P determination are also used to determine N. Samples are digested with sulphuric acid and subsequently with hydrogen peroxide in Kjeldahl tubes. Digested solutions along with phenol and buffered alkaline hypochlorite r...

SIMPLE, RAPID TEST-TUBE EXIRACTION TECHNIC for the determination of urinary 17-ketosteroids has seen developed in our laboratories. A complete urinary 17-ketosteroid determination was carried out in a glass stoppered photometer cuvet by combining this extraction technic with a colorimetric method. Three colorimetric methods, Zimmermann (1), (2), Pincus (3), and Cohen and Kaluszyner (4) were com...

VARIETY of methods is available for tue colorimetric determination of uric acid. In general, these are based on precipitation of proteins, followed by the reduction in an alkaline medium of phosphotungstate by the uric acid ill the protein-free filtrate. Results of colorimetric determinations may at times vary from “true” uric acid values as determined by unease methods. This is because the col...

An improved colorimetric method for determination of cyanide content in bitter almond oil was developed. The optimal determination parameters were as follows: volume ratio of hydrochloric acid to bitter almond oil (v/v), 1.5:1; holding time for hydrolysis, 120 min; and volume ratio of distillation solution to bitter almond oil (v/v), 8:1. Analytical results showed that the relative standard dev...