[Selective membrane electrode for the determination of ammonia released from rubber caps of containers for parenteral solutions (author's transl)]. / Selektive Membranelektroden zur Bestimmung des aus Gummiverschlüssen von Behältern parenteraler Lösungen freigesetzten Ammoniaks.

It is dealt with an ammonia-selective membrane electrode for the quantitative determination of volatile amines and ammonia released from rubber caps of containers for parenteral solutions. The optimal measurement parameters were determined. It was demonstrated that the electrode is well suited for ammonia determinations in the range of 10(-6) to 10(-1) mol/l. As this method requires but little time and yields accurate results, it will be helpful in laboratories with heavy routine workloads. Fifteen different caps based on natural rubber, chlorobutyl rubber or bromobutyl rubber were tested for their usefulness as packaging materials for drugs. According to the amounts of released ammonia, the caps were classified into three categories.

[Quantitative determination of phenols by bromination surveyed from an unusual perspective]. / A fenolok brómozásos tartalmi meghatározása szokatlan nézópontból tekintve.

The substitution reaction of phenols and bromine yields, beside brominated phenols, hydrogen bromide as well. In the course of the quantitative potentiometric analysis of the latter we may obtain quantitative and structural information with regard to the investigated phenol compound in one step. Such information may include data regarding substitution of the aromatic ring, the detectability of a resorcine-skeleton or phenol-carboxylic acid moiety, etc. With the help of the titration curve, sometimes one can detect two subsequent reaction steps or two simultaneously existing materials on the basis of the measured hydrogen bromide/brominated phenol ratio. We demonstrate here how and old technique can be used to solve analytical problems with new perspective, as exemplified by the cases of phenol, resorcine, 8-oxy-quinoline and salicylic acid.

[Determination of thiocarbamide and related derivatives using an S-alkylation reaction]. / Tiokarbamid és néhány származékának meghatározása S-alkilezési reakcióval.

S-alkylation reaction based on the Hantzsch synthesis followed by cyclization and aromatization reactions were used to develop an analytical procedure. The various thiocarbamide derivatives were transformed to substituted aminothiazol by using suitable alpha-halogenoketones as the reagents. At the end of the reaction the reaction products are present as 2-aminothiazol salts. The acidimetric determination of the latter can easily be performed using acetone or methanol as the solvents and 0.1 M sodium hydroxide as the titrant. The forming 2-aminothizols with their different basicities are characteristic of the parent thiocarbamide derivatives. On the basis of the different basicities their simultaneous determination is possible and the shape of the titration curves enables the thiocarbamides to be characterized and identified.

[Analysis of steroids. Part 44: Analytical investigation of the intermediates of the synthesis of pipecuronium bromide (Arduan)]. / Adatok a szteránvázas vegyületek analitikájához 44. Pipecuronium bromid (Arduan) szintézis intermedierjeinek analitikája.

The following methods are described for the analytical investigation of the intermediates of the synthesis of pipecuronium bromide (Arduan) (for the numbering of the intermediates and their impurities see Figure 1.). 1. Gas chromatographic methods (capillary GC using fused silica capillaries Ultra-2 and Silar 10C WCOT) for the impurity profiling of intermediates I, II, IV and V including the identification and spectroscopic characterization of their impurities; 2. TLC methods for the similar characterisation of the further intermediates (III, VI, VII and VIII); 3. Gas chromatographic assay methods for IV and V using fused silica capillary technique and internal standards; 4. Potentiometric titration methods for the determination of VII and VIII using 0.1 M hydrochloric acid as the titrant.

[Analysis of steroids. Part 45: Analytical investigation of pipecuronium bromide (Arduan)]. / Adatok a szteránvázas vegyületek analitikájához 45. Pipecuronium bromid (Arduan) analitikai vizsgálata.

The following methods are described for the analytical investigation of pipecuronium bromide. 1. HPLC method. Of the several systems tried for the separation and quantification of impurities and degradation products the best results were obtained using silica as the stationary phase and 43:43:14 mixture of methanol, acetonitrile and concentrated aqueous ammonia containing 0.1 mole/l each of ammonium chloride and ammonium carbonate as the eluent. The validation of this method is presented. The above described aggressive eluent can be successfully replaced by an ion-pairing system using silica as the stationary phase and 96:4 mixture of acetonitrile and water containing 0.1 mole/l sodium perchlorate as the eluent. 2. Thin-layer chromatography. TLC systems are described for the separation and densitometric quantification of the impurities and degradation products of pipecuronium bromide. 3. Spectrophotometry. Two methods are described. The ester groups of the molecule can be determined by the iron(III)-hydroxamate method while for the ion-pair extraction of the quaternary ammonium steroid picric acid or bromthymol blue are used as the reagents. 4. Titrimetry. In addition to the titration with acetous perchloric acid for the assay of the bulk material a microtitration method is described for the determination of pipecuronium bromide in individual lyophylized ampoules (potentiometric titration with 0.1 M silver nitrate).