Method and device for determining total organic carbon content of a biological sample

Abstract

A method and device for determining total organic carbon content (xTC) in a biological sample and simultaneous sample preparation for determining 14C activity (14A) by scintillation, wherein the method comprises the following steps: i. combusting the biological sample, obtaining gaseous CO 2, ii. putting the gaseous CO 2 in contact with at least one CO 2-absorbing reagent allowing CO 2 absorption by the CO 2-absorbing reagent, iii. measuring the heat released during the absorption of the CO 2 by the CO 2-absorbing reagent through measurement of a range of temperature values, iv. at the end of step iii., adding a scintillation liquid for 14C to the CO 2-absorbing reagent that has absorbed the CO 2 produced by the combustion of the biological sample, obtaining a scintillation cocktail, v. determining the total organic carbon content (x TC) of the biological sample by means of a calibration curve that correlates the carbon content of the biological sample to the temperature maximum recorded in step iii., wherein the scintillation cocktail is a suitable sample for the determination of 14C activity (14A) by scintillation.

Description

[0001] METHOD AND DEVICE FOR DETERMINING TOTALORGANIC CARBON CONTENT OFA BIOLOGICALSAMPLE

[0002] TEXT OF THE DESCRIPTION

[0003] FIELD OF THE INVENTION

[0004] The present invention concerns a method for determining total organic carbon content present in a biological sample and simultaneous sample preparation for determining14C activity by liquid scintillation and the related device.

[0005] BACKGROUND OF THE INVENTION

[0006] The European Climate Law (PE / 27 / 2021 / REV / 1) has established the European Union''s objective of pursuing climate neutrality, achieving it by 2050. This objective implies development and technological innovation in the field of products of biological origin. The carbon footprint of an object and the sustainability of a product is linked to its content of biological origin. The international standard UNI EN 16640:2017 specifies now to determine this quantity using the14C method. Another standard, UNI EN 21644:2021, applies instead to secondary solid fuels. Also in this case, the component of biological origin is the discriminating factor for identifying a sustainable energy production process.

[0007] The measurement of the carbon content of biological origin by liquid scintillation requires a sample preparation that is destructive because it entirely converts the carbon into CO2 by combustion. It also requires two separate sampling and measurement processes, one for the determination of total organic carbon (TOC) and another for the measurement of14C activity . OBJECT AND SUMMARY OF THE INVENTION

[0008] The object of the present invention is to overcome the drawbacks of current techniques that involve two different sampling methods for the determination of the total organic carbon and14C activity.

[0009] According to the invention, this object is achieved thanks to the method and the device specified in the following claims, which are intended to form an integral part of this description.

[0010] The method described here allows to eliminate the systematics due to double sampling, to simplify the measurement method, to reduce the necessary instrumentation thus containing the costs, exploiting, for the measurement of TOC, the exothermicity of the absorption of the CO2 produced during the preparation of the sample for the measurement of14C activity.

[0011] In one embodiment, the present invention relates to a method for determining total organic carbon content (XTC) in a biological sample and simultaneous sample preparation for determining14C activity (14A) by scintillation comprising the following steps: i. combusting the biological sample, obtaining gaseous CO2, ii. putting the gaseous CO2 in contact with at least one C02~absorbing reagent allowing gaseous CO2 absorption by the CCt-absorbing reagent, iii. measuring the heat released during the absorption of gaseous CO2 by the C02~absorbing reagent through measurement of a range of temperature values, iv. at the end of step iii., adding a scintillation liquid for14C to the CCh-absorbing reagent that has absorbed the gaseous CO2 produced by the combustion of the biological sample obtaining a scintillation cocktail, v. determining the total organic carbon content (XTC) of the biological sample by means of a calibration curve that correlates the carbon content of the biological sample to the temperature maximum (AT) recorded in step iii., wherein the scintillation cocktail is a suitable sample for the determination of14C activity (14A) by scintillation .

[0012] Tn one embodiment, the present invention concerns a device suitable for performing said method.

[0013] The invention will now be described, by way of example only, with reference to the attached drawings, in which:

[0014] ~ Figure 1. Diagram of an embodiment of a device suitable for performing the method of the present invention .

[0015] - Figure 2. Example of temperature pulse.

[0016] - Figure 3. Correlation of the amplitude of the recorded thermal pulses with the total carbon content in samples of different matrix (cellulose, sucrose, standard beech wood IDE 240) .

[0017] DETAILED DESCRIPTION OF THE INVENTION

[0018] The invention will now be described in detail, by way of non-limiting example. in the following description, numerous specific details are provided to allow a complete understanding of the embodiments. The embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, etc. in other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the embodiments. Reference throughout this specification to ''one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of the terms "in one embodiment" or "in an embodiment" at various points throughout this specification do not necessarily all refer to the same embodiment. Furthermore, the particular feature, structure, or characteristic may be combined in any suitable manner in one or more embodiments.

[0019] The headings provided herein are for convenience only and do not construe the scope or meaning of the embodiments.

[0020] In one embodiment, the present invention relates to a method for determining total organic carbon content (XTC) of a biological sample and simultaneous sample preparation for determining14C activity (14A) by scintillation comprising the following steps: i. combusting the biological sample, obtaining gaseous CO2, ii. putting the gaseous CO2 in contact with at least one CO2--absorbing reagent allowing CO2 absorption by the C02-absorbing reagent, iii. measuring the heat released during the absorption of gaseous CO2 by the COa-absorbing reagent through measurement of a range of temperature values, iv. at the end of step iii., adding a scintillation liquid for14C to the C02~absorbing reagent that has absorbed the gaseous CO2 produced by the combustion of the biological sample obtaining a scintillation cocktail, v. determining the total organic carbon content (XTC) of the biological sample by means of a calibration curve that correlates the carbon content of the biological sample to the temperature maximum (AT) recorded in step ill., wherein the scintillation cocktail 1 s a suitable s amp 1 e for the d e t e r m i n a t i o n of14C activity (14A) by liquid scintillation.

[0021] In oonnee embodiment, tthhee combustion of the sample (step i.) is performed in excess of gaseous oxygen.

[0022] In one embodiment, the CO2-absorbing reagent is an organic compound capable of absorbing CO2, giving rise to an exothermic reaction.

[0023] In one embodiment, the CO2-absorbing reagent 1 s selected from 3-methoxypropylamine, ethanolamine, (5M) ethanolamine in 2 -methoxyethanol .

[0024] In oonnee embodiment, the COz-absorbing reagent i s employed in an amount sufficient to absorb CO2 up to a saturation of approximately 80%. It is in fact advisable that the COz~absorbing reagent be used in an amount such as to reach a CO2 saturation of a maximum of 80% so that the measurement of the total organic carbon content (XTC) is correct and there is nnoo underestimation of this quant i ty . When the C O2 - ab s o r b i ng reagent 1 s 3- me t h o x y p r o p y 1 am i n e , the maximum absorption capacity is

[0025] 4.8 10~3mmo 1 / ml , such that the amount will be calculated in relation to the weight of the biological sample being analyzed..

[0026] In one embodiment , t h e t emp e r a t u r e me a. s u r emen t in step iii. is performed at a frequency greater than 1 Hz.

[0027] In one embodiment , the calibration curve is represented by the formula

[0028] ΔT * * * -k

[0029] Pl (mdry Xyc) + p2 (mdry XTC ) 2 (1) wherein

[0030] XTC is the total organic carbon content of the sample, mdry is the dry mass of the sample,

[0031] AT is the measured temperature maximum, pl and p2 are two constants.

[0032] In one embodiment, the constants pl and p2 are determined by calibration; for example, by inserting samples containing different and known amounts of total carbon into the device, collecting at least 5 calibration points that include the extremes of the applicability range of the method. For example, if the device can measure samples that are up to 80% saturated with 3- methoxypropylamine, and assuming to use 10 mL of 3- methoxypropylamirie, the calibration should range from about 50 mg, corresponding to the cellulose cone without sample, up to 460 mg of total carbon. By recording five (or more) temperature points, a least-squares fit can be performed using the calibration function described above to determine the values of the constants pl and p2.

[0033] In one embodiment, pl is equal to 8.14 10~2°C / mg, and p2 is equal to -1.0910“4°C2 / mg2.

[0034] The total organic carbon content is proportional to the difference between the temperature maximum recorded during combustion and the initial temperature before combustion (measured over a period of about 30 s before the start of combustion).

[0035] The calibration was performed with a second-degree polynomial where the constant term was set to zero to force a null response to a null stress, namely to impose the passage through the origin of the axes. This corresponds to the absence of thermal response in the absence of carbon in the sample. The non-linear term, x?ith a negative sign, describes the saturation effect probably due both to the upcoming saturation of the CO2- absorbing reagent and to the time profile of gaseous CO2 generation during the combustion of the sample. An instantaneous combustion corresponds to a linear temperature response. The longer the combustion time, the greater the amount of heat that flows towards the thermal bath (environment) with the effect of reducing the amplitude of the thermal pulse to its maximum. Of course, the combustion time is positively correlated to the mass of the sample, and this to its total organic carbon content. A least squares fit was performed, where the uncertainty of the experimental points was assumed for all equal to + / - 0.5UC according to what was stated by the manufacturer of the temperature sensor. With this assumption, the quality of the fit is acceptable in a chi-square test at a 90% significance level. in one embodiment, the present invention relates to a device for performing the method described above. The device comprises:

[0036] - a combustion chamber 5, configured to accommodate a biological sample for respective combustion, a combustion gas transfer line 6 in flow connection with the combustion chamber 5,

[0037] - a carbon ampoule 15 and a reaction column or bubbler 14 in flow connection with line 6, wherein the column or bubbler 14 and the ampoule 15 are intended to contain a CO2--absorbing reagent, the ampoule 15 and the column or bubbler 14 being connected in series along line 6,

[0038] - a first source 13 (for example a reservoir) of the CCh-absorbing reagent in flow connection writh the column or bubbler 14 and the ampoule 15 to feed the CO2- absorbing reagent within the column or bubbler 14 and the ampoule 15,

[0039] - a second source 12 (for example a reservoir) of a scintillation liquid for14C in flow connection with the column or bubbler 14 and the ampoule 15 to feed the scintillation liquid inside the ampoule 15, the source 12 being connected in bypass to the line 6, particularly downstream of the column or bubbler 14, but arranged to percolate the scintillation liquid for14C into the column or bubbler 14,

[0040] - a temperature sensor 18 operatively coupled to the column or bubbler 14, configured to measure temperature changes within the column or bubbler 14, and

[0041] - a processor 20 designed to store the temperature values measured by the temperature sensor 18 and to correlate the total carbon content to the temperature maximum recorded by the temperat.ure sensor 18.

[0042] In one embodiment, the device comprises a gaseous oxygen supply line 4 in flow connection with the combustion chamber 5, configured to supply gaseous oxygen to the combustion chamber 5.

[0043] In one embodiment, the device comprises, on the combustion gas transfer line 6, downstream of the combustion chamber 5 and upstream;of the carbon ampoule 15, a condenser 7 or the like, configured to remove water vapor contained in the combustion gas.

[0044] In one embodiment, the device 100 further comprises at 1east one of:

[0045] - a heat exchange device 9 in flow connection with the carbon ampoule 15, configured to condense water vapor present in the combustion gas; a third source (for example a reservoir) 22 configured to contain a second scintillation liquid for tritium in flow connection with a tritium ampoule 8 designed to collect the water vapor extracted from the combustion gas and the second scintillation liquid for tritium.

[0046] In various embodiments, the heat exchange device 9 is operative along the line 6 between the tritium ampoule 8 and the third source 22.

[0047] In various embodiments, downstream of the heat exchange device 9 and upstream of the third source 22, a filter 10 is provided on line 6, configured to remove particulate matter from the combustion gas.

[0048] Materials and Methods

[0049] The following materials are required to implement a preferred embodiment of the device described herein: laboratory combustion chamber or tube furnace (for example Perkin Elmer Sample Oxidizer A307 or Carbolite Gero),

[0050] - digital thermometer (for example Maxim Integrated DS18B20),

[0051] - readout electronics (for example Arduino Uno),

[0052] 3-methoxypropylamine (for example Carbosorb Perkin Elmer).

[0053] Nothing in the method or device requires specific construction features of any of the products mentioned. Manufacturers and trade names are provided for reference and example only.

[0054] The requirements for producing the device completely overlap with those required for measuring the content of carbon of biological origin as reported in the UNI EN 16640:2017 standard and those of the UNI EN 21644:2021 standard for the liquid scintillation method.

[0055] Figure 1 shows a diagram of a preferred embodiment of a device (indicated by 100) for simultaneously measuring total carbon content and preparing a sample for determining14C activity by liquid scintillation.

[0056] Device 100 includes the combustion basket 1 for biological sample 2. Combustion basket 1 integrates or has associated heating means. For example, the basket 1 may comprise or be composed of a platinum filament, suitable for heating by passing an electric current, and is movable by means of a pneumatic arm. The sample is contained in a relative container, for example it is positioned in a cellulose cone, with sizes suitable for being inserted into the combustion basket 1.

[0057] At the start of the method, the basket 1 containing biological sample 2 is inserted into the combustion chamber 5, which is hermetically sealed in a gas-tight manner according to known methods . The combustion chamber 5 is in flow connection, particularly at its upper end, with the gas transfer line 6. The combustion chamber 5 consists, for example, of a transparent bottle, sealed by suitable sealing means (for example O-ring seals,1at. tne connection to Lne gas transfer line 6 and the housing of the combustion basket 1.

[0058] The combustion chamber 5 is also connected, preferably in a sealed manner, to a water supply line 3 and to the oxygen supply line 4.

[0059] With a suitable timer, for example mechanical (not illustrated), it is possible to select the combustion time. This defines the interval between, on the one hand, the closing of the combustion chamber 5, the ignition of the biological sample 2, the simultaneous supply of oxygen into the combustion chamber 5, which occurs by opening a valve on the oxygen supply line 4, and, on the other hand, the opening of the combustion chamber 5 to air, at the end of the combustion of the biological sample. An oxygen cylinder with a purity > 99.9% is preferably connected to an expansion volume and a pressure regulator (not shown), which supplies oxygen to the combustion chamber 5 via line 4, at a pressure higher than atmospheric pressure, preferably equal to 45±2 psig. The combustion time is selected so as to ensure complete combustion of the sample, where complete combustion of the sample corresponds to an absence of visible light emission from the combustion chamber 5 for 30 s, which will be the time before the opening of the chamber 5 to the laboratory atmosphere.

[0060] The combustion gas transfer line 6 transfers combustion gas from the combustion chamber 5 to a waste gas tank 17, where excess combustion gas is bubbled into water and then vented to the atmosphere; the combustion gas transfer line 6 must be hermetically sealed during the entire combustion time of the sample.

[0061] Prior to the start of combustion, the CO?-absorb!ng reagent is dispensed from the first source 13 to the column or bubbler 14 and the ampoule 15 via a dispenser, preferably a mechanically adjustable piston dispenser (not shown), to define the amount of the CCy-absorbing reagent dispensed. The CCh-absorbing reagent, preferably in liquid form, adheres to the walls of the ampoule 15 and the column or bubbler 14, which is downstream of the ampoule 15; the excess part of the absorbing reagent is collected in the ampoule 15 positioned lower than the column or bubbler 14. Both portions of the CCb-absorbing reagent (present in the ampoule 15 and in the column or bubbler 14 respectively) will take part in the absorption reaction of the CO2 contained in the combustion gas.

[0062] During combustion, the gas produced by the combustion of the biological sample flows from the combustion chamber 5 through the combustion gas transfer line 6 to the condenser 7 (preferably a condensation radiator), designed to eliminate the water vapor component present in the combustion gas by condensing it and collecting it by gravitation in the tritium ampoule 8. The combustion gas continues through the gas-tight heat exchange device 9 having the function of condensing the water vapor still present in the combustion gas, where the collected water vapor is fed to the tritium ampoule 8. The combustion gas then flows through the filter 10, which has the role of eliminating particulate matter from the combustion gas, and is preferably made up of fine grids in succession, separated from each other by glass wool. Downstream of the filter 10 there may be a three- way valve 11 that allows, respectively, the passage of (i) water for cleaning the combustion gas transfer line 6 and the combustion chamber 5, (ii) the combustion gas towards the ampoule 15 and (iii) the scintillation liquid for tritium intended to be fed to the tritium ampoule 8.

[0063] The aqueous component of the combustion gas may also be subject to evaluation of the amount of tritium present. In such circumstances, the scintillation liquid for tritium, contained in the tank 22, is fed to the tritium ampoule 8 via the three-way valve 11, obtaining the second scintillation cocktail for tritium subsequently intended to be inserted into a scintillator, where the emission of light in the visible (following stimulation with ionizing radiation) is correlated to the amount of tritium present in the biological sample.

[0064] The pressure inside the device allows the combustion gas to rise along the column or bubbler 14, coming into contact with the CCg-absorbing reagent. The column 14, made of thermally conductive material (for example metal), is in thermal contact with the carbon ampoule 15 and with the temperature sensor 18, preferably coupled to the column 14.

[0065] The absorption of gaseous CO2 by the CCu-absorbing reagent occurs both directly on the internal surface of the column 14 and on the surface of the liquid of the CO2--absorbing reagent contained in the ampoule 15. The heat developed by the absorption reaction is transferred to the column 14 both by direct conduction, by the part of the CCD-absorbing reagent adhered to the walls of the column 14, and indirectly, by evaporation of the CO2- absorbing reagent from the ampoule 15 flowing inside the column 14.

[0066] The temperature sensor 18 (preferably a thermometer, more preferably a digital thermometer) is powered and read with a frequency > 1 Hz by a front-end electronic board 19 via a 1-Wire protocol. In turn, the front-end electronics communicate (preferably via USB) with the data processor 20 where the acquired temperature data are read and stored on disk for subsequent analysis.

[0067] The temperature rise recorded by the temperature sensor 18 can be measured, during the analysis, as the maximum of the recorded thermal pulse, subtracted from a starting temperature, for example obtained by averaging 30 s of sampled data before the start of combustion. By calibrating the amplitude of the thermal pulses and measuring the amplitude of the thermal pulse AT by applying formula 1, the total organic carbon content XTC is measured.

[0068] The absorption of the carbon dioxide produced during the combustion of the biological sample by the CO2~absorbing reagent, preferably 3-methoxypropylamine, which occurs in column 14 and in the ampoule 15, is an exothermic process, and the heat released is directly proportional to the amount of CO? absorbed, since it corresponds to the difference in chemical energy between the unbound and bound CO2 molecules.

[0069] Once combustion is complete, the flow of combustion gas is interrupted between the ampoule 15 and the column 14 by a pneumatic mechanism (not illustrated). A controlled amount of scintillation liquid for14C is then dispensed from the second source 12 containing the scintillation liquid for14C, preferably via a dispenser (for example a mechanically adjustable piston dispenser, not shown) to define the amount of liquid dispensed. The mixture of scintillation liquid for14C and C02~laden CO2- absorbing reagent is called the14C scintillation cocktail and is collected in the ampoule 15, which mixture constitutes a sample useful for measuring the14C activity.

[0070] The ampoule 15 may then be removed, capped, and inserted into a measuring device (for example Hidex 300 SL) sensitive to near-ultraviolet light to read the scintillation light and thus determine the14C activity (14A).

[0071] At the end of the method, it is possible to perform a cleaning cycle of the ducts and combustion chamber 5 by injecting a small quantity of water through the water supply line 3, and finally the combustion basket 1 is removed from the combustion chamber 5.

[0072] P-esults and Discussion

[0073] Figure 2 shows a temperature pulse recorded with the device described above. The temperature sampling frequency inside the reaction column 14 is 1 Hz. Figure 3 also shows the trend of the amplitude of the temperature pulse recorded as a function of the amount of total organic carbon present in the combusted sample. When this was composed of multiple components, the components, individua11y weighed dur1ng preparation, were added to determine the total carbon content.

[0074] The trend of the thermal amplitude as a function of the total carbon of the combusted sample is linear in the low mass region, below 250 mg of carbon. Above this threshold, a linear model tends to overestimate the experimental data. For this reason, it is necessary to apply a non-linear correction to the response model. Combustion is not instantaneous, and the time required to completely oxidize a sample that saturates the CCt- absorbing reagent at 80% is greater than that necessary for the oxidation of a smaller mass. The order of magnitude of the oxidation times varies from a few seconds to a few minutes, and is also dependent on the matrix considered. The method described herein is industrially applicable in radiological analysis and characterization laboratories for environmental monitoring.

[0075] The content of carbon of biological origin XBTC can be expressed as: wherein

[0076] 4A_ is the activity of14C contained in the sample measured by liquid scintillation, m is the mass ot the sample,

[0077] XTC is the mass fraction of organic carbon contained in the sample and ao is a constant that expresses the specific activity of a sample of biological origin 100%.

[0078] The constant ao is 13.56 dpm / gC (disintegrations per minute / per unit of dry mass of carbon) and must be corrected for the year of production of the sample due to the variation in the relative abundance of14C compared to stable isotopes due to nuclear tests in the 60s and the use of fossil fuels.

[0079] When the measurements of14A and x?c are performed with two separate samplings, the measurement systematics are independent and both contribute to the measurement uncertainty. The procedure described here allows to reduce the sensitivity of the method to the sampling systematics and, in general, to the inhomogeneity of the sample in terms of total organic carbon content. It also allows to optimize the measurement method, since it reduces the number of devices necessary to produce the result, with a consequent reduction in management complexity (characterization, quality control, maintenance) and therefore ultimately allows the laboratory to provide more correct measurements. Description of reference symbols

[0080] 1. Combustion basket

[0081] 2. Sample

[0082] 3. Water line for combustion chamber

[0083] 4. Oxygen line for combustion chamber

[0084] 5. Combustion chamber

[0085] 6. Gas transfer line

[0086] 7. Condensation radiator

[0087] 8. Tritium ampoule

[0088] 9. Exchange column

[0089] 10. Filter

[0090] 11. Three-way valve

[0091] 12. Source of scintillation liquid for14C

[0092] 13. C02-absorbing reagent tank

[0093] 14. Reaction column / bubbler

[0094] 15. Carbon ampoule

[0095] 16. Liquid waste tank

[0096] 17. Gas waste tank

[0097] 18. Temperature sensor

[0098] 19. Temperature sensor front-end electronics

[0099] 20. Computer

[0100] 22. Source of scintillation liquid for tritium

Claims

Claims1. A method for determining total organic carbon content (XTC) of a biological sample and simultaneous sample preparation for determining14C activity (14A) by scintillation comprising the following steps:

1. combusting the biological sample, obtaining gaseous CO2, ii. putting the gaseous CO2 in contact with at least one C02-absorbing reagent allowing CO2 absorption by the C02-absorbing reagent, iii. measuring the heat released during the absorption of gaseous CO2 by the C02-absorbing reagent through measurement of a range of temperature values, iv. adding a scintillation liquid to the CO2- absorbing reagent that has absorbed the gaseous CO2 produced by the combustion of the biological sample obtaining a scintillation cocktail, v. determining the total organic carbon content (XTC) of the biological sample by means of a calibration curve that correlates the carbon content of the biological sample to the temperature maximum (AT) recorded in step iii., wherein the scintillation cocktail is a suitable sample for the determination of14C activity (14A) by scintillation.

2. The method according to claim 1, wherein the combustion of the sample (step i.) is performed in excess of gaseous oxygen.

3. The method according to claim 1 or claim 2, wherein the C02-absorbing reagent is an organic compound capable of absorbing CO2 by an exothermic reaction.

4. The method according to any one of the preceding claims, wherein the CCh-absorbing reagent is selected from 3-methoxypropylamine, ethanolamine, ethanolamine in 2-methoxyethanol .

5. The method according to any one of the preceding claims, wherein the heat measurement in step iii. is performed at a frequency equal to or greater than 1 Hz.

6. The method according to any one of the preceding claims, wherein the calibration curve is represented by a curve having formula (1)AT = pl * (mdry * XTC) + p2 * (mdry * xTC)2(1) whereinXTC is the total organic carbon content of the samp1e, mdry is the dry mass of the combusted sample,AT is the measured temperature maximum, pl and p2 are constants.

7. The method according to any one of the preceding claims, wherein the CCh-absorbing reagent is employed in an amount sufficient to absorb the total gaseous CO2 produced by the combustion of the biological sample up to a saturation of 80%.

8. A device (100) for determining total organic carbon content (XTC) of a biological sample and simultaneous preparation of a sample suitable for determining14C activity (14A) by scintillation, wherein the device comprises: a combustion chamber (5), configured to accommodate a biological sample for respectivecombustion, a combustion gas transfer line (6) in flow connection with the combustion chamber (5),- a carbon ampoule (15) and a reaction column or bubbler (14) in flow connection with the line (6), wherein the column or bubbler (14) and the ampoule (15) are intended to contain a CCh-absorbing reagent,- a first source (13) of a CCt-absorbing reagent in flow connection with the column or bubbler (14) and the ampoule (15) to feed the CCh-absorbing reagent within the ampoule (15) and the column or bubbler (14),- a second source (12) of a scintillation liquid for14C in flow connection with the column or bubbler (14) and the ampoule (15) to feed the scintillation liquid inside the ampoule (15),- a temperature sensor (18) operatively coupled to the column or bubbler (14), configured to measure temperature changes within the column or bubbler (14), and- a processor (20) designed to store the temperature values measured by the temperature sensor (18) and to correlate the total carbon content to the temperature maximum recorded by the temperature sensor (18).

9. The device according to claim 8, comprising a gaseous oxygen supply line (4) in flow connection with the combustion chamber (5), for supplying gaseous oxygen to the combustion chamber (5).

10. The device according to claim 8 or claim 9, comprising on the combustion gas transfer line (6), downstream of the combustion chamber (5) and upstream of the carbon ampoule (15), a condenser (7) configured to remove water vapor contained in the combustion gas.

11. The device according to any one of claims 8 to 10, comprising at least one of:- a heat exchange device (9) in flow connection with the carbon ampoule (15), configured to condense water vapor present in the combustion gas;- a tritium ampoule (8) and a third source (22) configured to contain a second scintillation liquid for tritium in flow connection with the tritium ampoule (8), wherein the tritium ampoule (8) is intended to collect the water vapor extracted from the combustion gas and the second scintillation liquid for tritium.

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