Jadwiga Opydo

Determination of aluminium in tree samples by cathodic adsorptive stripping voltammetry.

This paper presents a method of determination of aluminium in tree samples (wood, leaves, roots) based on the cathodic adsorptive stripping voltammetry. Al(III) complexed with alizarin S was determined by ASV method using a hanging mercury drop electrode. Optimal conditions were found to be: accumulation time 30-90 s, accumulation potential - 0.70 V versus SCE, supporting electrolyte 0.1 M ammonia-ammonium chloride buffer at pH 8.2 and concentration of alizarin 1 x 10(-5) M. The response of the system, a linear current-concentration relationship was observed up to 8 x 10(-6) M. The developed method has been tested by analysing international reference materials (BCR 62 Olive leaves and BCR 101 spruce needles).

Dietary fluoride intake from infant and toddler formulas in Poland

Risk of enamel fluorosis associated with excessive fluoride intake during infancy and early childhood has been widely reported in literature. Results of several studies indicate that infant formula consumption, especially in the form of powdered concentrate, may appreciably increase childrens fluoride exposure in optimally fluoridated communities. The aim of the study was to measure fluoride content of infant and toddler formulas available in Poland and to discuss implications of the results. Twenty nine brands of powdered formulas were evaluated. Analyzes were performed with the use of ionselective fluoride electrode (09-37 type) and a RAE 111 chloride-silver reference electrode (MARAT). Results revealed that concentration of fluoride in all products was low (mean 29.0 μg/100 g), and that the formula itself is not a significant source of fluoride exposure. However, when reconstituted with water containing more than 0.5 ppm of fluoride, starting formulas and follow-on formulas may provide a daily fluoride intake of above the suggested threshold for fluorosis. Thus, fully formula-fed infants consuming mother milk substitutes prepared with optimally fluoridated water may be at increased risk of dental fluorosis.

Fluoride content of beverages intended for infants and young children in Poland.

Results of the studies indicate that fluoride content in beverages may be highly variable and children can consume substantial amounts of fluoride with these products. Ingestion of excessive fluoride during infancy and early childhood may cause dental fluorosis of permanent maxillary central incisors--the most aesthetically important teeth. The aim of this study was to determine the fluoride content in Polish beverages designed for infants and young children nutrition. Forty-three brands of juices and juice-flavored drinks and 23 instant teas were evaluated. Analyses were performed with the use of ion-selective fluoride electrode (09-37 type) and a RAE 111 chloride-silver reference electrode (MARAT). Fluoride concentrations in most beverages did not exceed 0.3 ppm. However, in three beverages containing tea extract levels of fluoride were higher (0.35-1.14 ppm). Consumption of these beverages could significantly increase childs fluoride exposure. Therefore, the need exists for continuous monitoring of fluoride levels in products intended for children. Listing fluoride content on beverages would be desirable. Knowledge about possible fluoride ingestion from dietary sources permits the clinician to recommend the safest schedule of fluoride treatment so as the optimal caries preventive effect can be obtained and the risk of dental fluorosis reduced.

Salivary Fluoride Concentrations and Fluoride Ingestion Following Application of Preparations Containing High Concentration of Fluoride

The aim of the study was to assess salivary fluoride concentrations and ingestion of fluorides after five different techniques of topical fluoride treatment. Ten volunteers received applications of fluoride gel, toothpaste, and foam. Fluoride concentrations were determined using ion-selective fluoride electrode in the samples of unstimulated saliva before and after procedures. The amounts of fluoride applied, recovered from the mouth, and retained in the mouth were calculated for each treatment. It was proved that fluoride ingestion following tray application of fluoride foam was significantly lower than ingestion following tray applications of fluoride gel (p < 0.01). The use of limited amounts of fluorides on a tray resulted in similar fluoride retention and lower ingestion comparing to the method which involves a large portion of fluorides followed by rinsing. Tooth brushing resulted in high salivary retention rates per amount of fluorides used in the procedure. These data provide initial concept about the possible advantages of some methods of topical fluoride application over others.

Determination of thallium in the presence of large excess of lead by anodic stripping voltammetry

The paper is concerned with the determination of traces of thallium, as T1(I), in the presence of very large amounts of lead, by d.c. anodic stripping voltammetry, by adding both a complexing agent and anionic surfactant. The supporting complexing agent was 0.1M solution of EDTA (pH 4.4). The influence of the several surfactants on the signals of lead and thallium was investigated.In 0.1M EDTA at pH 4.4 at the absence of a surfactant, lead does not interfere at concentrations below 10−4M. When the electrolyte contains also an anionic surfactant, lead can be tolerated at concentrations up to 2 × 10−3−6 × 10−3M (depending on the type of the surfactant), and the height of the thallium peak remains unaffected. This makes the determination of 10−8M T1(I) possible when the molar excess of lead is 2–6 × 105 fold. The method has been tested by determining the thallium content of soil extracts.

Electric strength of vacuum systems with Co-Mo alloy coated Cu electrodes

The paper presents the results of investigations of the electric strength at 50 Hz AC voltage of vacuum insulation systems that were not subjected to conditioning. The experiments have shown that a Co-Mo alloy coating electrolytically deposited on the surface of copper electrodes causes, at the pressure 2 mPa, >25% increase of electric strength of unconditioned vacuum insulation systems. This breakdown strength decreases with increasing gap spacing between the electrodes, and amounts /spl sim/17 kV/mm for systems with Cu electrodes at the electrode gap of 1 mm, and /spl sim/9 kV/mm at a gap of 6 mm. Plane electrodes with rounded-off edges of Rogowskis profile were used in the investigations. The electrodes with 50 mm diameter, were made of OFHC Cu. The paper shows the influence of the value of pressure from /spl sim/1 mPa to 1 Pa and at constant pressure of /spl sim/1 mPa, the length of vacuum gap, and the presence of a Co-Mo alloy layer coating the electrodes. >

Influence of cobalt-molybdenum-alloy coating on the surface of copper electrodes upon electric strength of unconditioned vacuum-insulation systems

The paper presents the results of investigations of electric strength at AC voltage (50 Hz) of vacuum insulation systems which were not subject to conditioning. Plane electrodes with rounded-off edges of Rogowskis profile were used in the investigations. The electrodes, having diameters of 50 mm, were made of OFHC copper. The paper shows the influence of fundamental factors defining the conditions of a vacuum insulation system on its electric strength, such as: the value of pressure (within the scope of approximately 1 mPa - 1 Pa) and at constant value pressure approximately 1 mPa, the length of vacuum gap, and the pressure of cobalt-molybdenum alloy layer coating the surfaces of the electrodes.