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Neutron-activation analysis of manganese in polysulphide materials
(Received 24 April 1967. Accepted 1 June 1967)
As .4 result of our continuing efforts to apply neutron-activation analysis (NAA) to various matrices containin a variety of elements which are not easily determined by other techniques, we have develope d:a method for determining manganese in poiysulphide adhesives. Manganese, as manganese dioxide, is added to these adhesives as a catalyst, and the “curing rate” is dependent on its concentration, Wet chemical determination of manganese in these samples can be tedious and time-sum&, whereas neutron-activation anakis urovides speed and sensitivity, and is nondestructive. Thz use of neuron-~~va~on ana@& td determine rn~g~e~ in various mater@ has been reported by other authors. Q The cross-section (13 barns) and the half-life (2.58 hr) are an ideal combination for analysis in the absence of interfering elements. EXPERIMENTAL A@C-WWS y-counting. TMC 4O&cimme1 anaiyser with 3 x 3 hr. sodium iodide crystal (T1 activated) Reactor. The Sandia Engineering Reactor Facility (SERF), with a thermal flux of approximately
2 x 10’”n cm-a se& . Polyethylene rabbits.
honored ~~~~~~de s#~rd (256% Mir), Add a kuown amount of MnQ, to pure poiysufpbide material, mix well and altow to harden.
Samples of the standard material, pure manganese metal, and manganese dioxide were irradiated in SERF for times ranging from 5 min to 2 hr and then allowed to “cool” for approximately 30 mm. The nuclear reaction used was $&Mn(n,r)““Mn. Manganese-56 has a half-life of 258 hr and decays with emission of 0.845, 1.81, and 2*12-MeV gamma rays. To obtain analytical information, the net counts for the @845-MeV photopeaks of the standard material, the manganese metal, and the manganese dioxide were intercompared. No diSerences were found and any of these three materials could therefore be used as standards. These results were verified by ~te~ornp~g the net counts for both the 1*81-and 2.f2-MeV photopeaks of these three materials. All three were used as standards for manganese ~~ysulp~~e unknowns and no sign&ant difference was found in the tioaI resuits. An hradiation time of 20 min was found to be quite sufficient for determining manganese in the unknowns* RESULTS
AND
DISCUSSION
The gamma-ray spectra for our h-radiated samples were identical with the standard spectra for 6@Mnpresented by Heath.s The accuracy and precision of this method were determined by doing two sets of 56 analyses of the standard material (256% Mn). The results showed the standard material contained 2.56% of manganese (standard deviations 0.07% and 0.08% Mn). The @845-MeV photopeak of 6EMn was used in all cases. As noted previously, the cross-section of saMn and the half-life of 6aMn make an ideal combiuation for analysis in the absence of interfering elements. However, the application of this method to less favourabie sample systems woufd require the analyst to determine whether there were any serious interferences from r~~onuc~des of other elements in the sample. * This paper was presented at the Southwest Regional American Chemical Society Meeting, Nuclear and ~di~he~t~ Section, ~b~uerque, New Mexico, 30 November-2 December 1966. 1339
Short communications
1340
With the irradiation conditions used (20”min irradiation at 2 x 10”’ n cm-* set-r, 30&n preliminary decay time), 1 ,ug of manganese can be determined. With a 24-hr irradiation and other irradiation conditions remaining constant, 80 ng of manganese could, theoretically, be determined. Acknowledgement-me authors wish to thank N. 3. DeLoilis and 0. Montoya, This work was supported by the United States Atomic Energy Commission.
Sandia Laboratory.
F. J. CONRAD B. T. KENNA
Analytical Method Development Division 1121 Sandia L&oratory A~~~uer~ue, New Mexico, U.S.A.
Smnmarv-A fast non-destructive neutron-activation analysis method has beendeveloped for manganese in polysulphide adhesives. Samples are irradiated for 20 min at a thermal flux of 2 x lO**n cm-* set-‘. The net activity in the 0.845MeV gamma peak of 60Mn produced by the (n, y) reaction in the sample is compared with the activity obtained from a weighed amount of pure manganese irradiated at the same time. Samples containing 2-3x of manganese have been analysed with a relative standard deviation of 2.9 %.
Zussamenfassung-Eine schnelle zerstiirungsfreie neutronenaktivierun~aIvti~he Methode zur Bestimmung van Mangan in Polysu~~le~rn wurde entwickelt. Die Proben-werden 20 &n bei einem therm&hen Flu13 von 2 * lox0 n cm-% se-z-’ best&h. Die Nettoaktivitat im 0,845 MeV-Gammapeak des durch die (n,y)-Reaktion in der Probe gebildeten sBMn wird mit der Aktivitat verglichen, die man in einer gleichzeitig bestrahlten gewogenen Menge reinen Mangans erhalt. 2-3 ‘A Mangan enthaltende Proben wurden mit einer relativen Standardabweichung von 2,9 % analysiert.
R&xun&Gn a blabore une methode rapide non destructive d’analyse par activation de neutrons pour le manganese dans des adhesifs polysulfures. Les echantillons sont irradies pendant 20 mn ii un On compare l’activite flux thermique de 2 x 1Oro n cm+ xc-l globale du pit gamma 0,845-MeV du 66Mn produit par la &action (n, y) dans ~~h~t~on a l’activite obtenue B partir dune quantite pes& de manganese pur irradif: au m&me moment. On a analyse des echantillons contenant 2-3x de manganese avec un &art type relatif de 2,9 %. REFERENCES 1. G. W. Leddicotte, The ~io~~t~ of Manganese. National Academy of Science, Nuclear Science Series, NAS-NS-3018,196O. 2. M. Rakovic, Application of Neutron Activation Analysis for the DeteTm~tion of Elements in Organic Materiafs. Radioizotopy-Pristroje, Jadema Energie sv. 11, 1965; Translated by Tolos Associates Urbanek, Palo Alto, California, No, 165, August, 1966. 3. R. L. Heath, Scintillation Spectrometry Gamma Ray Spectrum Catalogue, IDO-16880-2, Vol. 2, 2nd. Ed. August, 1964.
As .4 result of our continuing efforts to apply neutron-activation analysis (NAA) to various matrices containin a variety of elements which are not easily determined by other techniques, we have develope d:a method for determining manganese in poiysulphide adhesives. Manganese, as manganese dioxide, is added to these adhesives as a catalyst, and the “curing rate” is dependent on its concentration, Wet chemical determination of manganese in these samples can be tedious and time-sum&, whereas neutron-activation anakis urovides speed and sensitivity, and is nondestructive. Thz use of neuron-~~va~on ana@& td determine rn~g~e~ in various mater@ has been reported by other authors. Q The cross-section (13 barns) and the half-life (2.58 hr) are an ideal combination for analysis in the absence of interfering elements. EXPERIMENTAL A@C-WWS y-counting. TMC 4O&cimme1 anaiyser with 3 x 3 hr. sodium iodide crystal (T1 activated) Reactor. The Sandia Engineering Reactor Facility (SERF), with a thermal flux of approximately
2 x 10’”n cm-a se& . Polyethylene rabbits.
honored ~~~~~~de s#~rd (256% Mir), Add a kuown amount of MnQ, to pure poiysufpbide material, mix well and altow to harden.
Samples of the standard material, pure manganese metal, and manganese dioxide were irradiated in SERF for times ranging from 5 min to 2 hr and then allowed to “cool” for approximately 30 mm. The nuclear reaction used was $&Mn(n,r)““Mn. Manganese-56 has a half-life of 258 hr and decays with emission of 0.845, 1.81, and 2*12-MeV gamma rays. To obtain analytical information, the net counts for the @845-MeV photopeaks of the standard material, the manganese metal, and the manganese dioxide were intercompared. No diSerences were found and any of these three materials could therefore be used as standards. These results were verified by ~te~ornp~g the net counts for both the 1*81-and 2.f2-MeV photopeaks of these three materials. All three were used as standards for manganese ~~ysulp~~e unknowns and no sign&ant difference was found in the tioaI resuits. An hradiation time of 20 min was found to be quite sufficient for determining manganese in the unknowns* RESULTS
AND
DISCUSSION
The gamma-ray spectra for our h-radiated samples were identical with the standard spectra for 6@Mnpresented by Heath.s The accuracy and precision of this method were determined by doing two sets of 56 analyses of the standard material (256% Mn). The results showed the standard material contained 2.56% of manganese (standard deviations 0.07% and 0.08% Mn). The @845-MeV photopeak of 6EMn was used in all cases. As noted previously, the cross-section of saMn and the half-life of 6aMn make an ideal combiuation for analysis in the absence of interfering elements. However, the application of this method to less favourabie sample systems woufd require the analyst to determine whether there were any serious interferences from r~~onuc~des of other elements in the sample. * This paper was presented at the Southwest Regional American Chemical Society Meeting, Nuclear and ~di~he~t~ Section, ~b~uerque, New Mexico, 30 November-2 December 1966. 1339
Short communications
1340
With the irradiation conditions used (20”min irradiation at 2 x 10”’ n cm-* set-r, 30&n preliminary decay time), 1 ,ug of manganese can be determined. With a 24-hr irradiation and other irradiation conditions remaining constant, 80 ng of manganese could, theoretically, be determined. Acknowledgement-me authors wish to thank N. 3. DeLoilis and 0. Montoya, This work was supported by the United States Atomic Energy Commission.
Sandia Laboratory.
F. J. CONRAD B. T. KENNA
Analytical Method Development Division 1121 Sandia L&oratory A~~~uer~ue, New Mexico, U.S.A.
Smnmarv-A fast non-destructive neutron-activation analysis method has beendeveloped for manganese in polysulphide adhesives. Samples are irradiated for 20 min at a thermal flux of 2 x lO**n cm-* set-‘. The net activity in the 0.845MeV gamma peak of 60Mn produced by the (n, y) reaction in the sample is compared with the activity obtained from a weighed amount of pure manganese irradiated at the same time. Samples containing 2-3x of manganese have been analysed with a relative standard deviation of 2.9 %.
Zussamenfassung-Eine schnelle zerstiirungsfreie neutronenaktivierun~aIvti~he Methode zur Bestimmung van Mangan in Polysu~~le~rn wurde entwickelt. Die Proben-werden 20 &n bei einem therm&hen Flu13 von 2 * lox0 n cm-% se-z-’ best&h. Die Nettoaktivitat im 0,845 MeV-Gammapeak des durch die (n,y)-Reaktion in der Probe gebildeten sBMn wird mit der Aktivitat verglichen, die man in einer gleichzeitig bestrahlten gewogenen Menge reinen Mangans erhalt. 2-3 ‘A Mangan enthaltende Proben wurden mit einer relativen Standardabweichung von 2,9 % analysiert.
R&xun&Gn a blabore une methode rapide non destructive d’analyse par activation de neutrons pour le manganese dans des adhesifs polysulfures. Les echantillons sont irradies pendant 20 mn ii un On compare l’activite flux thermique de 2 x 1Oro n cm+ xc-l globale du pit gamma 0,845-MeV du 66Mn produit par la &action (n, y) dans ~~h~t~on a l’activite obtenue B partir dune quantite pes& de manganese pur irradif: au m&me moment. On a analyse des echantillons contenant 2-3x de manganese avec un &art type relatif de 2,9 %. REFERENCES 1. G. W. Leddicotte, The ~io~~t~ of Manganese. National Academy of Science, Nuclear Science Series, NAS-NS-3018,196O. 2. M. Rakovic, Application of Neutron Activation Analysis for the DeteTm~tion of Elements in Organic Materiafs. Radioizotopy-Pristroje, Jadema Energie sv. 11, 1965; Translated by Tolos Associates Urbanek, Palo Alto, California, No, 165, August, 1966. 3. R. L. Heath, Scintillation Spectrometry Gamma Ray Spectrum Catalogue, IDO-16880-2, Vol. 2, 2nd. Ed. August, 1964.