Chromatographic determination of itopride hydrochloride in the presence of its degradation products

Two sensitive and reproducible methods are described for the quantitative determination of itopride hydrochloride (IH) in the presence of its degradation products. The first method is based on HPLC separation on a reversed phase Kromasil column [C18 (5-microm, 25 cm x 4.6 mm, ID)] at ambient temperature using a mobile phase consisting of methanol and water (70:30, v/v) adjusted to pH 4.0 with orthophosphoric acid with UV detection at 258 nm. The flow rate was 1.0 mL per min with an average operating pressure of 180 kg/cm2. The second method is based on HPTLC separation on silica gel 60 F254 using toluene:methanol:chloroform:10% ammonia (5.0:3.0:6.0:0.1, v/v/v/v) as mobile phase at 270 nm. The analysis of variance (ANOVA) and Student's t-test were applied to correlate the results of IH determination in dosage form by means of HPLC and HPTLC methods. The drug was subjected to acid and alkali hydrolysis, oxidation, dry heat, wet heat treatment, UV, and photodegradation. The proposed HPLC method was utilized to investigate the kinetics of the acidic, alkaline, and oxidative degradation processes at different temperatures and the apparent pseudo-first-order rate constant, half-life, and activation energy were calculated. In addition the pH-rate profile of degradation of IH in constant ionic strength buffer solutions in the pH range 2-11 was studied.     

Wavelength accuracy testing of UV-visible detectors in liquid chromatography

Summary Wavelength accuracy is an important factor of LC detection which can have serious effects on detector response, analytical results, and inter-laboratory reproducibility. Current wavelength accuracy test procedures for LC detectors have serious limitations or are very elaborate. This paper describes two new test procedures which employ Tb⁺³ and Er⁺³ solutions, these ions have narrow well defined absorption bands, and provide suitable test points throughout the ultraviolet-visible spectrum. These new test methods are fast, simple, applicable to any detector, and cover the spectral regions most frequently employed in LC detection.     

Proficiency test on the determination of mineral oil from polluted soils

Mineral oil products are abundant sources of environmental contamination. A Finnishproficiency test was carried out to investigate the quality of data provided in an analysis of mineral oil in polluted soils. The homogeneity and stability of the samples were tested. The calculated concentration or the median value of the results was used as the assigned value because of the unavailability of certified reference materials (CRMs). The samples were analysed using an infrared spectroscopy (IR) or gas chromatography (GC) procedure. Even if the participating laboratories had little experience with GC, the results were promising. Hence, the GC procedure will replace IR as the new ISO standard (ISO/DIS 16703) in the near future in many Finnish environmental laboratories. There is a need for CRMs for the determination of mineral oil using the GC method due to common contamination problems caused by mineral oil. Received: 9 December 2001 Accepted: 14 February 2002     

DSC Investigation of some Testing and Calibration Compounds, Particularly During Cooling

Two compounds are described with interesting properties for use in DSC. The first compound is adamantane (C₁₀H¹⁶), with a reversible solid-solid transition at 208.62 K [1], suitable for DSC calibration at this low temperature [2]. The second compound is 4,4'-azoxyanisole (C₁₄H₁₄N₂O₃), with a liquid crystal range between 390 and 407 K [3]. This compound shows two transitions on heating, with a large heat effect at 390 K and a small heat effect at 407 K. For this reason, this substance is well suitable for testing the sensitivity and the resolution of DSC instruments [4]. For both compounds not only the heating, but also the cooling behaviour is investigated.This revised version was published online in November 2005 with corrections to the Cover Date.     

分析测试中数据统计处理综合程序系统

近年来,分析测试数据已广泛应用计算机进行统计处理,文献报道的多是针对特定任务的单元程序,远不能适应分析测试数据统计处理多样性的要求。本文研究和开发了分析测试中常用数据统计处理的通用综合程序系统,操作方便,调用灵活,在单元程序的基础上,可以组合成各种综合程序,以满足不同分析测试数据统计处理的需要。     

A spot test for ammonium ion by the color band formation method

Removing nutrients from wastewaters is important in controlling eutrophication. Processes for removing nutrients require accurate control of operational conditions, and it is necessary to monitor nutrient concentrations during the removal process. For this purpose, a simple and accurate analytical method is especially important for small-scale wastewater treatment facilities. Here, we report a simple colorimetric method for determining NH₄⁺-N in wastewater. The method is to detect NH₄⁺-N by a color band length formed in a minicolumn, and similar methods for heavy metals detection were reported by Morosanova et al. In this study, the length of the color band of indonaphthol dye trapped on an adsorbent in a minicolumn was linearly correlated with NH₄⁺-N concentration in the range 1-10 mg NH₄⁺-N l⁻¹ under optimized conditions. This methods was developed on the basis of our previously reported color band methods for orthophosphate and nitrite determination, but the adsorbent used in this work consisted of an admixture of synthetic hydrotalcite particles and poly(vinyl chloride) particles coated with equal amounts of benzylcetyldimethylammonium chloride and biphenyl. When the method was applied to actual wastewaters, the results corresponded well with the results obtained by the standard method, and suspended solids (SS) and dissolved organic pollutants did not interfere with detection.     

Interpretation of interlaboratory comparison results to evaluate laboratory proficiency

Guidelines are given for the evaluation of proficiency test (PT) results in order to increase the effectivity of PT participation. For better understanding, some statistical background is given along with some examples to show the effects of the choices made by the PT provider. The calculation method of the assigned value and the selection of the standard deviation both affect the z-score that is used by the participating laboratory to judge the quality of its performance in the PT. Therefore, the participating laboratory is advised to use the PT results with care and, if necessary, to recalculate the z-scores. Finally, advice is given on how not to follow up bad PT results along with some valuable steps that could be part of an effective follow-up procedure.     

Proficiency tests for pharmaceuticals in different waters

To date there are no German or international standards for the analysis of pharmaceuticals in waters. The efficiency of the analytical methods—predominantly LC-MS/MS and GC-MS—used for trace analysis of pharmaceuticals is proved for the first time by proficiency tests using natural waters.Two proficiency tests for up to 11 different groups of pharmaceuticals in river water and waste water were carried out in 2000 (28 participants) and 2002 (20 participants). The spiking concentrations were 60–800 ng/L for surface water and 80–1280 ng/L for waste water. For most determinants good recovery rates (80–120%) and variations (around 35% for surface water and 50% for waste water) were reported.     

Ignition characteristics of forest species in relation to thermal analysis data

The ignitability of various forest species was measured with a specifically designed apparatus, under precisely controlled temperature and airflow conditions. The ignitability tests were based on ignition delay time versus temperature measurements using five different forest species: Pinus halepensis, Pistacia lentiscus, Cupressus sempervirens, Olea europaea, Cistus incanus. These species are common in the Mediterranean region and frequently devastated by forest fires. The ignition characteristics of the forest fuels examined were related to thermogravimetric analysis data. The DTG curves showed that the mass changes related to cellulose decomposition in the temperature range of 320–370 °C are greatly responsible for the ignition behavior of the species tested. In addition, the mass of volatiles evolving between 120–160 °C has a significant effect on the ignitability. On the contrary, the inorganic ash content of forest fuels, measured by atomic absorption spectroscopy, seems to play an insignificant role on the ignitability characteristics of the forest fuels examined.     

Proficiency test exercise on the determination of natural levels of radionuclides in mushroom reference material

The results from a proficiency test exercise for the determination of natural levels of radionuclides in mushroom reference material carried out by laboratories in six different countries are discussed. These laboratories submitted data on seven radionuclides, namely ¹³⁴Cs, ¹³⁷Cs, ⁴⁰K, ⁹⁰Sr, ²⁴¹Am, ²²⁶Ra, and ²¹⁰Po. However, only the data received for three of these radionuclides could be statistically evaluated to obtain consensus mean values and confidence intervals (at a significance level of 0.05). The contents of ¹³⁴Cs, ¹³⁷Cs and ⁴⁰K were quantified as 4.4, 2,899 and 1,136 Bq/kg, respectively.