GB2029014A

GB2029014A - A method of determining total organic halides in water

Info

Publication number: GB2029014A
Application number: GB7928148A
Authority: GB
Original assignee: Envirotech Corp
Current assignee: Envirotech Corp
Priority date: 1978-08-28
Filing date: 1979-08-13
Publication date: 1980-03-12
Also published as: DE2934561A1; FR2435036A1; DE2934561C2; NL7906423A

Abstract

A method of converting organic halides in a sample, such as drinking water or wastewater, from which inorganic halides have been removed, to measurable halides, comprises heating the sample in an inert atmosphere at a relatively low first temperature to vapourise water and low-temperature volatile organics therefrom, leaving a low-temperature sample residue, pyrolysing the low- temperature volatile organics at a higher second temperature in an atmosphere comprising a mild oxidant to convert all organic halide portions thereof to measurable halides, heating the low-temperature sample residue at a sufficient temperature to drive off high-temperature volatile organics, leaving a high-temperature sample residue, and pyrolysing the high- temperature volatile organics and the high-temperature sample residue to convert all organic halide portions thereof to measurable halides.

Description

SPECIFICATION A method of determining total organic halides in water.

TECHNICAL FIELD This invention provides a method for determining the total inorganic halide concentration in a liquid such as drinking water or wastewaten BACKGROUND ART Methods previousiy proposed for measuring the total organic halide concentration in a quantity of liquid, such as drinking water or wastewater, did not permit quantitative removal of organic halide species, both purgeable and non-purgeable, from the liquid to be tested. Furthermore, these methods did not permit quantitative titration of bromide species coulometrically and were generally slow as well as being characterised by poor reproducibility.

STATEMENT OF INVENTION AND ADVANTAGES It is an object of the present invention to alleviate the disadvantages of these prior proposals, and there is accordingly provided a method for converting organic halides in a sample to measurable halides, said sample having been pre-treated to remove inorganic halides therefrom, said method comprising the steps of:: a) heating said sample at a relatively low first temperature to vapourise water and lowtemperature volatile organics from said sample without causing sputtering of said water, thereby leaving a low-temperature sample residue; b) pyrolysing said low-temperature volatile organics at a second temperature, said second temperature being higher than said first temperature, to convert all organic halide portions of sa id low-temperature volatile organics to measurable halides; c) heating said low-temperature sample residue to vapourise high-temperature volatile organics therefrom, thereby leaving a high-temperature sample residue;; d) pyrolysing said high-temperature volatile organics to convert all organic halide portions of said high-temperature volatile organics to measurable halides, and e) pyrolysing said high-temperature sample residue to convert all organic halide portions of said high-temperature sample residue to measurable halides.

The sample may be obtained by passing a known quantity of a liquid to be tested for total organic halides through a bed of sorptive material, such as activated carbon, at a flow rate that permits diffusion of the liquid through the sorptive material. The organic species in the liquid, including organic halides, are removed from the liquid by adsorption and absorption on to the sorptive material. Thereafter, a halide ion displacement wash solution may be passed through the sorptive material to displace inorganic halides therefrom. The organic halides that have been sorbed by the sorptive material are then converted to measurable halides, in accordance with the present invention, so that a determination of the total concentration of organic halides in the liquid can be made.

According to a preferred embodiment of the method, a measured sample of the sorptive material, after having been pre-treated (i.e.

washed with a halide ion displacement solution to remove inorganic halides therefrom), is heated in a chemically inert atmosphere at a relatively low first temperature (e.g. 2000 C) to vapourise water and low-temperature volatile organics therefrom, thereby leaving a low-temperature sample residue. The rate of heating of this pre-treated sample at this first temperature is low enough to preclude any substantial sputtering of the sample, water or low-temperature residue. Thereafter, the low-temperature volatile organics are pyrolysed at a higher second temperature (e.g. 800 C) s & that all organic halide portions thereof can be converted to measurable halides.Also, the low temperature sample residue is heated at a relatively high temperature so as to vapourise high-temperature volatile organics therefrom, leaving a high-temperature sample residue.

Furthermore, according to the preferred embodiment, the iow-temperature volatile organics are pyrolysed in an atmosphere that is appropriate to convert all organic halide portions of the low-temperature volatile organics to measurable (e.g. titratable) halides. An appropriate atmosphere for this purpose comprises a mild oxidant such as carbon dioxide. Preferably such a mild oxidant atmosphere is free of oxygen or any other strongly oxidising gas, although oxygen or any other strongly oxidising gas could be present if diluted sufficiently (e.g. by an inert carrier gas) so as to prevent the formation of significant amounts of species such as bromine and oxybromo acids that are not coulometrically titratable.

The heating of the low-temperature sample residue to drive off the high-temperature volatile organics may, but need not necessarily, occur at the same second temperature (e.g. 8000 C) and in the same heating region as the pyrolysis of the low-temperature volatile organics. It is not a requirement of this invention that heating of the low-temperature sample residue and pyrolysis of the low-temperature volatile organics occur in the same region. However, using the preferred apparatus for the practice of this invention, both the low temperature sample residue and the low temperature volatile organics are heated sequentially in the same heating region.The high temperature volatile organics that are produced by heating the low-temperature sample residue at a higher second temperature can then be pyrolysed at a temperature, which may but need not necessarily be the same second temperature (e.g.

8000 C), in an atmosphere that is suitable to convert all organic halide portions of the high temperature volatile organics to measurable (e.g.

titratable) halides. A suitable atmosphere for the pyrolysis of the high-temperature volatile organics may comprise a mild oxidant such as carbon dioxide. Strongly oxidising gases are to be avoided, unless highly diluted so as to prevent the formation of significant amounts of non-titratable species.

The organic halide portions of the remaining high-temperature sample residue may then be converted to measurable halide species by complete oxidising, preferably in an atmosphere comprising an oxygen-containint gas. Such oxidation of the high-temperature sample residue may, but need not necessarily, occur at the same second temperature (e.g. 8000 C) and in the same heating region as the pyrolysis of the hightemperature volatile organics. When the hightemperature sample residue is oxidised and the atmosphere used to oxidise the sample contains oxygen, pyrolysis of the high-temperature volatile organics and oxidation of the high-temperature sample residue in the same heating region must occur in two successive time intervals. Therefore, the atmosphere of the heating region may initially comprise a mild oxidant gas that is low in oxygen content.This oxygen-lean atmosphere can be maintained for a sufficient interval of time to enable complete pyrolysis of the high-temperature volatile organics to occur, and thereafter, the atmosphere of the heating region is changed to comprise an oxygen-containing çlas such as air, which enables complete combustion of the hightemperature sample residue to occur. An atmosphere of carbon dioxide is suitable for pyrolysis of the high-temperature volatile organic.

After the organic halides in the pre-treated sample have all been converted to measurable halides in accordance with the method of the present invention, the measurable halides are then measured by a conventional technique such as coulometric titration.

FIGURES OF THE DRAWINGS FIGURE 1 is a schematic iliustration of an apparatus for removing organic species by sorption from a liquid to be tested for total organic halide concentration, and FIGURE 2 is a schematic illustration of an apparatus for converting organic halides in a sample to measurable halides according to the method of the present invention, and for subsequent titration of the measurable halides.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to the drawings, a known quantity of a liquid such as drinking water or wastewater to be tested for total organic halide concentration is passed through a packed bed of sorptive material that removes organic species, including organic halides, from the liquid by adsorption and/or absorption. An apparatus for accomplishing this sorption process is schematically shown in FIGURE 1. The apparatus comprises a plurality of containers 10, into each of which a known quantity of the liquid to be tested is placed. The containers 10 are mounted on a frame (not shown); and a plurality of columns 12 are detachably mounted in series (typically in pairs) to the containers 10 to receive flow from the containers 10. Each of the columns 12 contains a bed 22 of sorptive material such as activated carbon.A nitrate ion wash reservoir 14 is mounted to the frame, and the columns 12 are detachable mounted to receive wash solution from the reservoir 14. A pressurised tank (not shown) is provided for delivering an inert gas at a measured rate to the containers 10 and to the reservoir 14 via gas line 33, gauge 34 and valves 36.

Each of the containers 10 receives a known quantity of the liquid with a minimum of agitation, holds the liquid in a quiescent state, and releases the liquid at a measured rate. Each container 10 is made of a non-adsorptive material such as glass, and may suitably be cylindrically configured with a capacity for holding 100 millilitres. As shown in FIGURE 1, each container 10 has a removable gas-tight cap 16 and an inlet 18 for admitting inert gas through the cap 16. Each container 10 also has an outlet 20 for discharging liquid at a rate proportional to the rate at which the inert gas is admitted at the inlet 1 8. The outlets 20 and the columns 12 can be interconnected by, for example, a threaded O-ring compression fitting 23.

Each of the columns 12 can consist of a length of standard 2 mm l.D. capillary tubing into which the sorptive material is packed, and held in position with quartz wool 24, to form a bed 22.

Serially connected columns 12 can be coupled to one another by compression fittings 23. As liquid is passed through a column 12 from a container 10, or from a preceding column 12, organic species in the liquid, including organic halides, are sorbed on to the sorptive material in the bed 22.

The nitrate ion wash reservoir 14 holds a wash solution to be passed through the sorptive material in each column 12 after the known quantity of liquid to be tested has passed therethrough. This wash solution displaces inorganic halides adsorbed or absorbed by the sorptive material. The reservoir 14 can advantageously be a glass container having a capacity of 100 millilitres with a removable gastight cap 28.The reservoir 14 includes an inlet 30 for admitting inert gas through the cap 28, and an outlet 32 for discharging the wash solution at a rate proportional to the rate at which the inert gas is admitted at the inlet 30. The outlet 32 can be fluid-sealably connected to each of the columns 1 2 by means of a suitable compression fitting 23.

Other techniques, besides the use of pressurised gas, are possible for causing the discharge of liquid from the containers 10 and for causing the discharge of wash solution from the reservoir 14. For example, a manual or automated mechanical displacement device, such as a syringe or a suction device, could be used.

In cases where the liquid to be tested has been chlorinated, a means is provided for mixing a reducing agent (e.g. sodium sulphite or sodium thiosulphate) with the liquid prior to passing the liquid through the columns 1 2. The reducing agent eliminates residual chlorine interference by reducing chlorine to chloride.

A sample of sorptive material from the bed 22 in one of the columns 1 2, after having been pretreated (i.e. washed) with a halide ion displacement solution from the reservoir 14 to remove inorganic halides therefrom, is then processed according to the present invention whereby the organic halides that have been sorbed by the sorptive material are converted into measurable halides. An apparatus for so processing a sample of pre-treated sorptive material is shown schematically in FIGURE 2. A commercially available apparatus that is suitable for this purpose is the MCTS-20 microcoulometric titration system available from the Dohrmann Division of Envirotech Corporation, Santa Clara, California 95050, United States of America.

The apparatus illustrated in FIGURE 2 generally comprises a furnace unit 50 and a detector unit 52. The detector unit 52 can advantangeously be a titration cell, so that measurement of the measurable halides can be accomplished by coulometric titration. In principle, however, the practice of the present invention is not limited to any particular kind of detection technique.

The detector unit 52 is in gas flow communication with the furnace unit 50 to receive gases therefrom. The furnace unit 50 comprises a sample receiving region 54, a first heating region 56, and a second heating region 58. A conduit 59 within the furnace unit 50 extends from the sample receiving region 54 through the first heating region 56 to the second heating region 58. The furnace unit 50 is coupled to a first line 60 for introducing gas into the sample receiving region 54, a second line 62 for introducing gas into the conduit 59 downstream of the sample receiving region 54, and a third line 63 for introducing gas into the second heating region 58.

Gases so introduced into the furnace unit 50 exit therefrom through a conduit 64 to the detector unit 52.

In operation, a measured quantity of the pretreated sample is introduced into the sample receiving region 54. The pre-treated sample may be solid-particulate carbon with organic species (including organic halides) that have been removed from the liquid to be tested sorbed thereon. However, the method of this invention does not depend on the physical state of the sample, i.e. on whether the sample is a solid, liquid or gas. Various kinds of conventional sample receivers are available for receiving solids, liquids, or gases. In the apparatus illustrated in FIGURE 2, a boat 70 is used to receive wet activated carbon from the columns 1 2 shown in FIGURE 1.

The boat 70 is made of non-reactive material such as quartz, and is movable along the conduit 59, either manually or automatically, by means of a push rod 72 between three positions. The first position 74 for the boat 70 is located below a sealable opening 76 through which the measured quantity of sorptive material is introduced to the boat 70. The second position 78 is located in the first heating region 56, and the third position 80 is located in the second heating region 58.

In the first heating region 56, the pre-treated sample in the boat 70 is heated at a relatively low first temperature that is sufficient to evaporate water and readily volatile organics, leaving a lowtemperature residue in the boat 70. The rate of heating in the first heating region 56 is low enough to prevent any substantial amount of sputtering of water, sample material or lowtemperature residue.The minimum temperature needed in the first heating region 56 to vapourise water from the sample is about 600C.The maximum practicable temperature for avoiding water sputtering is about 4000 C. A preferred temperature range is between 1000C and 3000 C, and the preferred temperature in the first heating region 56 is about 2000 C. For optimum temperature control in the heating region 56, the portion of the conduit 59 at the first position 74 can be surrounded with cooling coils and/or heating elements. A pressurised inert gas is introduced into the sample receiving region 54 via the first line 60 in order to prevent back-diffusion into the sample of gases generated downstream in the conduit 59. Suitable inert gases for this purpose are argon and helium.

The gases generated in the first heating region 56 (i.e. water vapour and low-temperature volatile organic) are carried into and through the second heating region 58 towards the detector unit 52 by a carrier gas that is introduced into the conduit 59 via the second line 62 downstream of the sample receiving region 54. This carrier gas could consist initially of a substantially inert gas that does not react chemically with the volatile gases and water evolved in the first heating region 56.

Alternatively, the carrier gas could consist initially of a mild oxidant such as carbon dioxide for use further downstream in the second heating region 58 to pyrolyse the low-temperature and hightemperature volatile organics.

The gas initially introduced via the second line 62 is preferably oxygen-free during pyrolysis of the low-temperature and high-temperature volatile organics so as to suppress the formation of species such as bromine and oxybromo acids that are not coulometrically titratable. After pyrolysis of the low-temperature and hightemperature volatile organics in the second heating region 58 has been completed, the gas introduced via the line 62 is switched to a strongly oxidising gas (e.g. pure oxygen or air) to pyrolyse the high-temperature sample residue. An oxygenrich atmosphere to facilitate complete pyrolysis of the high-temperature sample residue in the second heating region 58 can be provided by introducing pure oxygen via a third line 63 into the gas flow path into the second heating region 58.It has been found that as the low-temperature sample residue is moved into the second heating region 58, if the atmosphere in the second heating region 58 is changed to an oxidising atmosphere by an appropriate switching of the gas introduced via the line 60 or the line 62, the resulting hightemperature volatile organics and hightemperature sample residue are pyrolysed together to yield pyrolysis products that are indistinguishable from each other. The atmosphere thus found in the second heating region 58 is suitable for the formation of coulometrically titratable species.

The atmosphere used in the first heating region 56 may comprise a mildly oxidant, oxygen-free gas, but it is also recognised that the atmosphere of':he first heating region 56 need not necessarily be oxygen-free or mildly oxidant. Thus, oxygen or any other strongly oxidising gas may be present in the first heating region 56, provided that the concentration of such oxygen or other strongly oxidising gas is low enough to preclude the formation of significant amounts of species that are not coulometrically titratable.Since heating is the only process that is intended to occur in the first heating region 56 so that water vapour and readily volatile organics can be driven off from the sample, an inert carrier gas of only commercial grade purity (i.e. a carrier gas that may include a sufficiently diluted quantity of an oxygencontaining gas such as air) is-suitable for introduction into the conduit 59 via the second line 62.

In the second heating region 58, the lowtemperature sample residue remaining in the boat 70 is heated at a higher temperature to convert all of the halogen-containing portions of the lowtemperature sample residue to measurable halides. The low-temperature volatile organics evolved in the first heating region 56 and the hightemperature volatile organics evolved in the second heating region 58 likewise undergo reactions in the second heating region 58 that convert all halogen-containing portions thereof to measurable halides.

The minimum temperature needed in the second heating region 58 to initiate combustion is about 5000C. Because of apparatus limitations (e.g. the softening temperature of the quartz boat 70), the maximum temperature for the second heating region 58 is about 12000 C. The preferred temperature range for the second heating region 58 is between 7000C and 10000C, and the preferred temperature is about 8000 C.

The conduit 64 connecting the furnace unit 50 to the detector unit 52 serves to convey all the gases evolved from the sample in the heating regions 56 and 58 to the detector unit 52. The conduit 64 can be made of glass tubing surrounded by a heating strip in order to maintain the temperature within the conduit 64 above 1000C so as to avoid condensation of water.

A suitable detector unit 52 is the titration cell described in U.S. Patent No. 3,427,238, the contents of which are incorporated herein by reference. Thus, as shown in FIGURE 2, the detector unit 52 comprises an electrolytic cell 82 containining an electrolyte; an inlet 84 for admitting the gaseous products from the furnace unit 50 to the cell 82; and an anode electrode 86, a cathode electrode 88 and a sensor electrode 90, each disposed in the electrolyte. The detector unit 52 also comprises a reference electrode 92 disposed in electrolytic communication with the electrolyte; suitable electrical circuitry (not shown) for operation of the detector unit 52; and a strip chart or other device (not shown) for recording the use of electrical power, which is proportional to the quantity of halides precipitated in the cell 82.

In practising the present invention, a volume of approximately 100 millilitres of the liquid to be tested, such as drinking water or wastewater, containing up to 500 parts per billion organic halides, is placed in one of the containers 1 0 with a minimum of agitation in order to minimise the escape of purgeable organics. For a liquid having a higher concentration of organic halides, a proportionally reduced volume of liquid can be processed, or alternatively the liquid can be diluted to lower the organic halide concentration.

A single container 10 is sufficient but the additional containers 10 may be provided so that confirmation measurements, or measurements on other samples, can be made concurrently.

The container 10 containing the liquid to be tested is gas-sealed with cap 16, and the gas line 33 is connected to the inlet 1 8. First and second columns 12, arranged in series and each containing a bed 22 of sorptive material, are connected to the outlet 20. The preferred sorptive material is ordinarily, because of subsequent combustion of the sorptive material, a tightly packed bed of finely ground activated carbon in the range of abput 100 to 400 mesh. However, for certain analysis techniques, synthetic porous polymer beads could be used as the sorptive material. For a 100 millilitre volume of liquid to be tested, 40 milligrams of activated carbon in each column 12 would be sufficient to remove substantially all of the organic halides in the column 1 2 nearest the container 10.The second column in series with the first column enables confirmation to be made of the sorption efficiency of the first column by providing a comparison of the background reading of the halide content of the sorptive material in the first column with ar, independently obtained reading for the second' column.

According to one method of passing liquid from the containers 10 into the columns 12, an inert gas such as helium or argon is introduced into the containers 10 through the line 33 at a rate that causes the liquid to flow through the columns 12 at a rate of approximately 3 millilitres per minute, which enables sufficient diffusion in the columns 12 to accomplish the sorption. The passage of a measured quantity of about 100 millilitres of liquid through the columns 12 takes about 30 minutes.

Other methods for passing liquid from the containers 10 into the columns 12 include use of a mechanical displacement device (e.g. a syringe) or a suction device.

After a measured quantity of liquid has passed through the columns 12, the columns are uncoupled from the containers 10 and are coupled to the reservoir 14. The reservoir 14 contains a halide ion displacement wash solution, which may be passed through the beds 22 in the same mannas as the liquid to be tested. Thus, an inert gas may be introduced to the reservoir 14 through line 33 so that the wash solution flows through the columns 12 at an appropriate rate such as one miililitte per minute. Alternatively, a mechanical displacement device or a suction device could be used.

The wash solution displaces inorganic halides such as sodiun cl7loride from the sorptive material. The quantify of wash solution passed through the columns 12 need not be measured precisely, and approximately 2 millilitres is su.ticient. Asuitable wash solution is an aqueous solution having a nitrate ion (NO3-) concentration range of from 0.01 N to 0.1 N depending upon characteristics of the particular batch of activated carbon used for the beds 22. If not removed, the inorganic halides typically found in drinking water would mask the organic halides to such an extent that a measurement of organic halide concentration would be inconclusive.It has been found tiat the above sorption process achieves good recovery of purgeable organic halides, such as CHIC13, arid non-purgeable organic halides, such as 2,4,6-tribromophenol. It is believed that these results are achieved because the liquid is not agitated during the sorption process.

The heating of the pre-treated sarnple occurs in the first heating region 56. Low-temperature volatile organics generated in the first heating region 56 are carried by a pressurised inert carrier gas from the line 62 into the second heating region 58, and thence through the conduit 64 to the detector unit 52. The low-temperature sample residue remaining in the boat 70 is then moved by means of the push rod 72 to the second heating region 58. The atmosphere of the second heating region 58 is controlled so that organic halides sorbed on to the sorption material can be converted to titratable halides, while the production of bromine and oxybromo acids (e.g.

hypobromous acid) is minimised.

A residence time of at least thirty seconds for the pre-treated sample in the first heating region 56 is required, and a residence time of about one minute is preferred. A residence time of about fifteen seconds is preferred for low-temperature volatile organic gases in the second heating region 58; and a residence time of at least two minutes is preferred for the low-temperature sample residue in the second heating region 58.

For the apparatus as described, it is appropriate to introduce 200 cc/min of gas into the furnace unit 50 at all times. Of this 200 cvc/min, about 100 cc/min may comprise the inert gas introduced via the first line 60. The other 100 cc/min may initially comprise either pure carbon dioxide introduced via the second line 62, or a combination of 50 cc/min of carbon dioxide from the second line 62 and 50 cc/min of oxygen from the third line 63. The gas introduced via line 60 or line 62 is subsequently changed to pure oxygen during the latter part of the combustion process in the second heating region 58. The gases evolved in the furnace unit 50 are continuously carried to the detector unit 52 where, in a conventional manner as described in the aforementioned U.S.

Patent No. 3,427,238, the organic halides in these gases may be titratable coulometrically.

As illustrated in FIGURE 2, the gases from the furnace unit 50 pass into the titration cell 82 through the inlet 84. Chloride, bromide and iodine ions are generated as the organic halides go into solution in the cell 82. These ions react very rapidly with silver ions in the electrolyte to form precipitates of silver chloride, silver bromide and silver iodide, respectively. This process reduces the concentration of the silver ions in the electrolyte, and consequently changes the tendency of silver to leave the sensing electrode 90. The electrical potential on the sensing electrode 90 is thereby changed, and the anode 86 becomes more positive. More electrons are thereby drawn from the anode 86 causing more silver ions to enter the electrolyte to restore the silver ion concentration.

A measured quantity of sorptive material from the second column 12 may be processed in the same way as described above for sorotive material from the first column. Ideally, the sorptiye material' in the second column 12 has not sorbed any additional organic halides, the organic halides having been completely removed from the liquid in the first column 12. As a consequence, the halide reading for the sorptive material in the second column should be substantially equal to the background reading of the halide content of the sorptive material. The chlorine background of activated carbon is normally constant for all carbon from the same batch, and hence chlorine background can be determined independently.The total organic halide determination for the first column is obtained by subtracting the background halide reading from the halide reading for the sorptive material in the first column.

With apparatus as described, the detection of measurable halides is limited to approximately one microgram per litre of liquid to be tested. The reproducibility is the higher of about + 1 microgram per litre of +3% of the total organic halide.

The sorption technique described herein can be used with other procedures for measuring organic halides, such as liquid chromatography or solvent extraction. Also, the combustion and titration techniques described above are not limited to use with samples prepared by the above-described sorption techniques. The sample to be treated by the heating and titration techniques described above can be in liquid, solid or gaseous form. The present invention is especially advantageous whenever a liquid to be tested contains bromide components that would otherwise pass through a titration phase as unmeasurable bromine gas or oxybromo acid.

The present invention has been described above in terms of a preferred embodnient which is to be construed as illustrative. The scope of the invention, however, is defined by the following

Claims

claims.

CLAIMS 1. A method for converting organic halides in a sample to measurable halides, said sample having been pre-treated to remove inorganic halides therefrom, said method comprising the steps of: a) heating said sample at a relatively low first temperature to vapourise water and lowtemperature volatile organics from said sample without causing sputtering of said water, thereby leaving a low-temperature sample residue; b) pyrolysing said low-temperature volatile organics at a second temperature, said second temperature being higher than said first temperature, to convert all organic halide portions of said low-temperature volatile organics to measurable halides;

c) heating said low-temperature sample residue to vapourise high-temperature volatile organics therefrom, thereby leaving a high-temperature sample residue;; d) pyrolysing said high-temperature volatile organics to convert all organic halide portions of said high-temperature volatile organics to measurable halides, and e) pyrolysing said high-temperature sample residue to convert all organic halide portions of said high-temperature sample residue to measurable halides.
2. The method of claim 1 with the additional step of measuring the measurable halides obtained from the pyrolysis of said lowtemperature volatile organics.
3. The method of claim 1 or claim 2 with the additional step of measuring the measurable halides obtained from the pyrolysis of said lowtemperature residue.
4. The method of any one of claims 1 to 3 wherein said step of heating said sample at said first temperature occurs in a chemically inert atmosphere.
5. The method of any one of the preceding claims wherein said first temperature is in the range from 600C to 4000C.
6. The method of claim 5 wherein said first temperature is 2000 C.
7. The method of any one of the preceding claims wherein said step of pyrolysing said lowtemperature volatile organics occurs in an atmosphere that is appropriate to convert said low-temperature volatile organics to titratable halides.
8. The method of claim 7 wherein said appropriate atmosphere comprises a mild oxidant and is oxygen-lean.
9. The method of claim 8 wherein said mild oxidant is carbon dioxide.
10. The method of any one of the preceding claims wherein said heating of said sample at said first temperature occurs in a first region; and wherein said pyrolysing of said low-temperature volatile organics, said heating of said lowtemperature sample residue, said pyrolysing of said high-temperature volatile organics and said pyrolysing of said high-temperature sample residue occur in a second region.
11. The method for converting organic halides in a sample to measurable halides, substantially as herein described with reference to FIGURE 2 of the accompanying drawings.