1、Designation: D3270 00 (Reapproved 2006)D3270 13Standard Test Methods forAnalysis for Fluoride Content of the Atmosphere and PlantTissues (Semiautomated Method)1This standard is issued under the fixed designation D3270; the number immediately following the designation indicates the year oforiginal ad
2、option or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods describe the semiautomated procedure for the analys
3、es of various types of samples for the purpose ofdetermining total fluoride. Since the test methods incorporate microdistillation of the sample, they may be applied to anyfluoride-containing solution where standards of identical composition have been carried through the same sample preparationproced
4、ures and have proven to provide quantitative recovery when analyzed by the semiautomated system. Conversely, themethods shall not be applied for analyses until the applicability has been demonstrated.1.2 In normal use, the procedure can detect 0.1 g/mL of F. The normal range of analysis is from 0.1
5、to 1.6 g/mL of F. Higherconcentrations can be analyzed by careful dilution of samples with reagent water. If digested samples routinely exceed 1.6 g/mLof F, the analytical portion of the pump manifold can be modified to reduce sensitivity. However, the best procedure is to analyzea smaller aliquot o
6、f the sample. Most accurate results are obtained when the fluoride concentration falls in the middle or upper partof the calibration curve.1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.4 This standard does not purport
7、 to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. See 8.3, 10.2.4, and 10.2.5 for additional precaut
8、ions.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD1356 Terminology Relating to Sampling and Analysis of AtmospheresD3266 Test Method for Automated Separation and Collection of Particulate and Acidic Gaseous Fluoride in the Atmosphere(Double Paper Tape Sampler Meth
9、od)D3267 Test Method for Separation and Collection of Particulate and Water-Soluble Gaseous Fluorides in theAtmosphere (Filterand Impinger Method)D3268 Test Method for Separation and Collection of Particulate and Gaseous Fluorides in the Atmosphere (SodiumBicarbonate-Coated Glass Tube and Particulat
10、e Filter Method)D3269 Test Methods for Analysis for Fluoride Content of the Atmosphere and Plant Tissues (Manual Procedures) (Withdrawn2010)3D3614 Guide for Laboratories Engaged in Sampling and Analysis of Atmospheres and Emissions3. Terminology3.1 DefinitionsFor definitions of terms used in these m
11、ethods, see Terminology D1356.1 These test methods are under the jurisdiction ofASTM Committee D22 on Air Quality and are the direct responsibility of Subcommittee D22.03 on AmbientAtmospheresand Source Emissions.Current edition approved April 1, 2006Oct. 1, 2013. Published May 2006October 2013. Ori
12、ginally approved in 1991. Last previous edition approved in 20002006 asD3270 - 00.D3270 - 00(2006). DOI: 10.1520/D3270-00R06.10.1520/D3270-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolu
13、me information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have
14、 been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official docu
15、ment.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Summary of Test Methods4.1 These semiautomated methods are based on the distillation of hydrogen fluoride (HF) from the sample and subsequentreaction of the distillate with aliza
16、rin fluorine blue-lanthanum nitrate reagent, to form a blue complex which is measuredcolorimetrically at 624 nm (1)4, or the subsequent measurement with a specific ion probe.4.2 General, Plant Material:4.2.1 The plant material including leaf samples, washed or unwashed, is dried, and ground, then di
17、ssolved with perchloric acidand diluted to 50 mL with water. In the case of leaf samples, an appreciable amount of fluoride may be deposited on the externalleaf surfaces. This fluoride behaves differently physiologically from fluoride absorbed into the leaf and it is often desirable to washit from t
18、he surface as a preliminary step in the analysis. Details of a leaf-washing process are described in 9.1.4.3 General, Atmospheric Samples:4.3.1 Test Methods D3269 contains acceptable procedures and also techniques for the proper preparation of atmosphericsamples. Test Methods D3266, D3267, and D3268
19、 are sampling procedures for ambient air and each method contains specificinstructions for sample preparation prior to analyses by the semiautomated method.4.4 General, System Operation:4.4.1 The dissolved digest is pumped into the polytetrafluoroethylene coil of a microdistillation device maintaine
20、d at 170C(2-6).Astream of air carries the acidified sample through a coil of TFE-fluorocarbon tubing to a fractionation column. The fluorideand water vapor distilled from the sample are swept up the fractionation column into a condenser, and the condensate passed intoa small collector. Acid and soli
21、d material pass through the bottom of the fractionation column and are collected for disposal. Acidand solid material pass through the bottom of the fractionation column and are collected for disposal. In the colorimetric method,the distillate is mixed continuously with alizarin fluorine blue-lantha
22、num reagent, the colored stream passes through a 15-mmtubular flow cell of a colorimeter, and the absorbance measured at 624 nm. In the potentiometric method, the distillate is mixedcontinually with a buffer, the mixed streams pass through a flow-through fluoride ion electrode, and the differential
23、millivoltageis measured with an electrometer. The impulse is transmitted to a recorder.4.4.2 All pieces of apparatus are commercially available, or may be adapted from commercially available equipment. The testmethod can also be run on most commercially available robot chemical analyzers. Details of
24、 construction of the microdistillationdevice are described in 7.10. Earlier versions of this test method have been published (3,5,6).4.5 Principle of Operation:4.5.1 Colorimetric SystemThe absorbance of an alizarin fluorine blue-lanthanum reagent is changed by very small amountsof inorganic fluoride
25、.4.5.2 Potentiometric SystemSince the sample system is the same for this procedure as for the colorimetric procedure, thedistillation step removes all of the interfering cations. The volatile acids that remain can be buffered by mixing with the Total IonicStrength Adjustment Buffer (TISAB).4.5.3 Dis
26、tillation SystemSince HF has a high vapor pressure, it is more efficiently distilled than the other acids previouslymentioned (4.5). The factors controlling efficiency of distillation are temperature, concentration of acid in the distillation coil, andvacuum in the system. Large amounts of solid mat
27、ter, particularly silicates, will also retard distillation. Accordingly, the smallestsample of vegetation consistent with obtaining a suitable amount of fluoride should be analyzed. The aforementioned conditionsmust be carefully controlled, since accurate results depend on obtaining the same degree
28、of efficiency of distillation from samplesas from the standard fluoride solutions used for calibration.4.5.4 Temperature control is maintained within 62C by the thermoregulator and by efficient stirring of the oil bath. Acidconcentration during distillation is regulated by taking plant samples in th
29、e range from 0.1 to 2.0 g and by using 100 6 10 mgof CaO and 3.0 6 0.1 g of NaOH for ashing and fusion of each sample. Vacuum in the system is controlled with flowmeters anda vacuum gage.Any marked change in vacuum (greater than 0.7 kPa or 0.2 in. Hg) over a short time period indicates either a leak
30、or a block in the system. Distillation should take place at the same vacuum each day unless some other change in the system hasbeen made. It is also essential to maintain the proper ratio between air flow on the line drawing liquid and solid wastes from thedistillation coil and on the line drawing H
31、F and water vapor (Fig. 1) from the distillation unit. Occasional adjustments on the twoflow-meters should be made to keep this ratio constant and to maintain higher vacuum on the line drawing HF vapor so that littleor no HF is diverted into the liquid and solid waste line. (See 10.3.4 for descripti
32、on of air flow system.)5. Significance and Use5.1 These test methods may be used for determining the fluoride content of particulate matter and gases collected from theatmosphere by passive and active means, including plant tissues. The user is warned that the fluoride content of passive collectors(
33、including plants) give only qualitative or semiquantitative measurement of atmospheric fluoride content.4 The boldface numbers in parentheses refer to the references at the end of this method.D3270 1326. Interferences6.1 Since the air that is swept through the microdistillation unit is taken from th
34、e ambient atmosphere, airborne contaminantsin the laboratory may contaminate samples. If this is a problem, a small drying bulb filled with calcium carbonate granules canbe attached to the air inlet tube of the microdistillation unit.6.2 If the polytetrafluoroethylene distillation coil is not cleane
35、d periodically, particulate matter will accumulate and will reducesensitivity.6.3 Silicate, chloride, nitrate, and sulfate ions in high concentration can be distilled with fluoride ion and will interfere with theanalysis by bleaching the alizarin fluorine blue-lanthanum reagent. Phosphate ion is not
36、 distilled, and therefore does not interfere.Metals such as iron and aluminum are not distilled and will not interfere with the analysis (most materials distilled over do notinterfere with the potentiometric method). Maximum concentrations of several common anions at which there was no detectableint
37、erference are given in Table 1. The sulfate concentration shown is the amount tolerated above the normal amount of sulfuricacid used in microdistillation. A number of materials cause changes in absorbance at 624 nm. Potential interfering substancescommonly found in plant tissues are metal cations su
38、ch as iron and aluminum, inorganic anions such as phosphate, chloride, nitrate,and sulfate, and organic anions such as formate and oxalate. Fortunately, metal cations and inorganic phosphate are not distilledin this system, and organic substances are destroyed by preliminary ashing. The remaining vo
39、latile inorganic anions may interfereif present in a sufficiently high concentration because they are distilled as acids. Hydrogen ions bleach the reagent which, inaddition to being an excellent complexing agent, is also an acid-base indicator. To reduce acidic interferences, a relatively highconcen
40、tration of acetate buffer is used in the reagent solution despite some reduction in sensitivity.7. Apparatus7.1 Multichannel Proportioning Pump, with assorted pump tubes, nipple connectors, glass connectors, and manifold platter.7.2 Pulse Suppressors, for the sample and alizarin fluorine blue-lantha
41、num reagent streams are each made from 3.05 m lengthsof 0.89-mm inside diameter polytetra fluoroethylene standard wall tubing. They are both an effective reagent filter and a pulsesuppressor. Discard them after one month of use. The outlet ends of the suppressor tubes are forced into short lengths o
42、f (0.081-in.)inside diameter silicone rubber tubing, that is then connected to the reagent pump tube, and the other end then slipped over theh fitting which joins the sample and reagent streams.7.3 Automatic Sampler, with 8.5 mL plastic sample cups.7.4 Voltage Stabilizer.7.5 Colorimeter (for colorim
43、etric method), with 15-mm tubular flow cell and 624-nm interference filters.7.6 Ion Selective Electrode Detector, (for potentiometric method) with flow-through electrodes.a Air Inlet g Waste Bottle with H2SO4b Microdistillation Coil h Gas-Drying Towerc Fractionation Column i T-Tubed Water-Jacketed C
44、ondenser j Vacuum Gaugee Sample Trap k Flowmeterf Waste Bottle l Vacuum PumpFIG. 1 Schematic Drawing of Air Flow System for Semiautomated Analysis of FluoridesTABLE 1 Maximum Detectable Concentration of Several AnionsPresent in Samples at Which There is No Detectable AnalyticalInterferenceCompound T
45、ested Interfering Anion Molarity ToleratedNa2SO4 SO4 (-2) 2 E-2Na2SiO3 SiO3 (-2) 5 E-3NaCl Cl(-1) 1 E-3NaH2PO4 PO4 (-3) 3.8NaNO3 NO3 (-1) 5 E-3D3270 1337.7 Rotary Vacuum and Pressure Pump, with continuous oiler.7.8 Recorder.7.9 Range Expander.7.10 Microdistillation ApparatusA schematic drawing is sh
46、own in Fig. 2. Major components of microdistillation apparatusinclude the following:7.10.1 Reaction Flask, 1000-mL, with a conical flange and cover (Fig. 2 A).7.10.2 Reaction Flask Flange Clamp (Fig. 2B).7.10.3 Variable Speed Magnetic Stirrer (Fig. 2D).7.10.4 Thermometer-Thermoregulator, Temperature
47、 Measuring Device-Thermoregulator, range 0 to 200C 200C. Temperaturemeasuring devices such as resistance temperature detectors, thermistors, and organic liquid-in-glass thermometers meetingrequirements of this application may be used. (Fig. 2 C).7.10.5 Electronic Relay Control Box.7.10.6 Immersion H
48、eater, 500 W (Fig. 2F).7.10.7 Flexible Polytetrafluoroethylene, TFE tubing, 4.8-mm outside diameter, 0.8-mm wall.A9.14-m length is coiled on a rigidsupport of such a diameter that the completed coil shall fit into the resin reaction flask (7.10.1). Care must be taken to preventkinking of the tubing.
49、7.10.8 Flowmeter, with ranges from 0 to 5 L/min, with needle valve control.7.10.9 Vacuum Gage, with a range from 0 to 34 kPa (254 torr).7.10.10 Microdistillation Column, (Fig. 2G, also see Fig. 3).7.10.11 Distillate Collector (Fig. 2I and Fig. 3).7.10.12 Water-Jacketed Condenser (Fig. 2H).7.10.13 Heat Exchange Fluid, for reaction flask (7.10.1).7.11 Mechanical Convection Oven.7.12 Wiley Cutting Mill.7.13 Crucibles, 40 mL, nickel, platinum or inconel.7.14 Muffle Furnace.7.15 pH Meter.8. Reagents and Materials8.1 Purity of ReagentsAll reagents shall conform to the speci
