2.1.5. Tubes for comparative tests

基本信息

• 标准
  欧洲药典
• 版本
  EP8.0
• 来源
  VOLUME 1
• 分类
  GENERAL CHAPTERS
• 页码
  17

EUROPEAN PHARMACOPOEIA 8.02.1.6. Gas detector tubes 01/2008:20105 2.1.5. TUBES FOR COMPARATIVE TESTS Tubesusedforcomparativetestsarematchedtubesof colourless glass with a uniform internal diameter. The base is transparent and flat. A column of the liquid is examined down the vertical axis of thetubeagainstawhitebackground,orifnecessary,againsta black background. The examination is carried out in diffused light. Itisassumedthattubeswithaninternaldiameterof16mm will be used. Tubes with a larger internal diameter may be usedinsteadbutthevolumeofliquidexaminedmustthenbe increased so that the depth of liquid in the tubes is not less than where the prescribed volume of liquid and tubes 16 mm in internal diameter are used. 01/2008:20106 2.1.6. GAS DETECTOR TUBES Gas detector tubes are cylindrical, sealed tubes consisting of an inert transparent material and are constructed to allow the passage of gas. They contain reagents adsorbed onto inert substrates that are suitable for the visualisation of the substancetobedetectedand,ifnecessary,theyalsocontain preliminary layers and/or adsorbent filters to eliminate substances that interfere with the substance to be detected. The layer of indicator contains either a single reagent for the detection of a given impurity or several reagents for the detection of several substances (monolayer tube or multilayer tube). The test is carried out by passing the required volume of the gastobeexaminedthroughtheindicatortube.Thelength of the coloured layer or the intensity of a colour change on a graduated scale gives an indication of the impurities present. The calibration of the detector tubes is verified according to the manufacturer’s instructions. Operating conditions.Examineaccordingtothemanufacturer’s instructions or proceed as follows: The gas supply is connected to a suitable pressure regulator andneedlevalve.Connecttheflexibletubingfittedwitha Y-piecetothevalveandadjusttheflowofgastobeexamined to purge the tubing in order to obtain an appropriate flow (Figure 2.1.6.-1). Prepare the indicator tube and fit to the metering pump, following the manufacturer’s instructions. Connect the open end of the indicator tube to the short leg of thetubingandoperatethepumpbytheappropriatenumber of strokes to pass a suitable volume of gas to be examined through the tube. Read the value corresponding to the length of the coloured layer or the intensity of the colour on the graduated scale. If a negative result is achieved, indicator tubes can be verified with a calibration gas containing the appropriate impurity. In view of the wide variety of available compressor oils, it is necessarytoverifythereactivityoftheoildetectortubesfor the oil used. Information on the reactivity for various oils is given in the leaflet supplied with the tube. If the oil used is not cited in the leaflet, the tube manufacturer must verify the reactivity and if necessary provide a tube specific for this oil. 1. Gas supply5. Indicator tube 2. Pressure regulator6. Indicator tube pump 3. Needle valve7. End open to atmosphere 4. “Y”-piece Figure 2.1.6.-1. –Apparatusforgasdetectortubes Carbon dioxide detector tube. Sealed glass tube containing adsorbent filters and suitable supports for hydrazine and crystal violet indicators. The minimum value indicated is 100 ppm with a relative standard deviation of at most ± 15 per cent. Sulfur dioxide detector tube. Sealed glass tube containing adsorbent filters and suitable supports for the iodine and starch indicator. The minimum value indicated is 0.5 ppm witharelativestandarddeviationofatmost±15percent. Oil detector tube. Sealed glass tube containing adsorbent filters and suitable supports for the sulfuric acid indicator. The minimum value indicated is 0.1 mg/m 3 with a relative standard deviation of at most ± 30 per cent. Nitrogen monoxide and nitrogen dioxide detector tube. Sealed glass tube containing adsorbent filters and suitable supports for an oxidising layer (Cr(VI) salt) and the diphenylbenzidine indicator. The minimum value indicated is 0.5 ppm with a relative standard deviation of at most ± 15 per cent. Carbon monoxide detector tube. Sealed glass tube containing adsorbent filters and suitable supports for di-iodine pentoxide, selenium dioxide and fuming sulfuric acid indicators. The minimum value indicated is 5 ppm or less, witharelativestandarddeviationofatmost±15percent. Hydrogen sulfide detector tube.Sealedglasstubecontaining adsorbent filters and suitable supports for an appropriate lead salt indicator. The minimum value indicated is 1 ppm or less, witharelativestandarddeviationofatmost±10percent. Watervapourdetectortube.Sealedglasstubecontaining adsorbent filters and suitable supports for the magnesium perchlorate indicator. The minimum value indicated is 67 ppm or less, with a relative standard deviation of at most ±20percent. General Notices (1) apply to all monographs and other texts17

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