Maciej Wojtczak

Use of ionic chromatography in determining the contamination of apple juice by lactic acid

High-performance anion exchange chromatography (HPAEC) with conductometric detection was used for the determination of the lactic acid content of apple juice subjected to fermentation with the strains of Lactobacillus brevis and Lactobacillus plantarum, obtained from a collection, at 20 and 30°C. At the same time, lactate content was determined by means of enzymatic tests and biosensors. Lactic acid concentrations determined by the chromatographic method are similar to those obtained during analysis by enzymatic tests. However, acid concentrations determined by means of biosensors substantially diverge from these results.

Content of iron, copper and zinc in white sugar samples from Polish and other European sugar factories

White sugar is a very pure food product, even though it contains very small, significant amounts of soluble and insoluble impurities. The content of these impurities has nutritional significance and determines the usefulness of sugar for various industrial applications. The aim was to evaluate the content of iron, copper and zinc in samples of white sugar from Polish factories compared with commercial white sugar samples from other European countries. The investigations were conducted on 72 campaign-averaged white sugar samples from 37 different Polish sugar factories from 1996 to 2000 and on 16 commercial white sugar samples from nine European countries. The content of iron, copper and zinc in those sugar samples was determined by means of FAAS both in the sediment and in the solution after filtration on 0.45-μm filters of sugar water solution. The content of iron, copper and zinc was low (averages 0.29, 0.06 and 0.07 mg kg-1, respectively) in all the white sugar samples from Polish sugar factories and other European countries. Iron and copper found in all white sugar samples were mainly in insoluble form - 77 and 69%, respectively. The contents of water-insoluble iron and water-soluble zinc in white sugar increase with a lowering of the quality of sugar evaluated according to the standards of the EU sugar market regime.

The relationship between plasma concentration of metoprolol and CYP2D6 genotype in patients with ischemic heart disease

BACKGROUND Metoprolol is the one of the most commonly used β-blockers in the treatment of ischemic heart disease and it is extensively metabolized in the liver undergoing oxidation by CYP2D6 isoenzyme of cytochrome P450. Gene encoding the CYP2D6 enzyme is characterized by genetic polymorphism. The CYP2D6 oxidation polymorphism has a major impact on the effectiveness and safety of the treatment. The aim of the study was to evaluate the relationship between plasma concentration of metoprolol and the CYP2D6 genotype in patients with ischemic heart disease. METHODS Fifty patients were interviewed and subsequently enrolled into the study. The patients received metoprolol twice daily at a dose of 50mg. The blood samples were analyzed for two major defective alleles for CYP2D6 - CYP2D6*4 and CYP2D6*3--by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Metoprolol concentration in plasma was determined by using the new and unique high-performance liquid chromatography (HPLC) method in the authors own modification with Corona CAD detector (Charged Aerosol Detection). RESULTS In the test group, genotypes conditioning poor oxidation (PM) occurred in 3 patients (6%), while 47 patients (94%) had genotypes coding for extensive metabolism (EM). Patients with PM genotypes had significantly higher plasma concentrations of metoprolol than the patients with EM genotype (mean 92.25 ± SD 36.78 ng/ml vs. mean 168.22 ± SD 5.61 ng/ml, respectively). Established relationships were statistically significant (NIR test, p=0.0009). CONCLUSIONS This study demonstrated that the CYP2D6 genotype remains a major determinant of the metoprolol plasma concentrations. The pharmacogenetic effect is likely to have consequences on both, the clinical benefit of metoprolol treatment and adverse drug reactions. The use of Corona CAD detector seems to be a very good alternative method for the determination of metoprolol concentration in plasma.

Starch Content in Various Types of Cane Sugars as a Criterion of Quality and Authenticity

Contrary to beet sugar, which on the market is used practically only as white sugar, cane sugar is used in a wide range of products for direct consumption. This article presents results of determination of starch content in different types of cane sugars: raw cane sugar, refined white cane sugar, plantation white sugar, and commercial “unrefined” brown and yellow sugars. The content of starch in various “brown” cane sugars ranged from 74 to 415 mg/kg, while in white sugars its content ranged from 51 to 214 mg/kg. The starch content in cane sugars should be an important criterion for the quality of cane sugars, which allowed to differentiate cane sugars from beet sugar containing no starch.