Non-destructive bone aluminum assay by neutron activation analysis

A non-destructive method based on instrumental neutron activation analysis (INAA) for the assay of aluminum in bone samples is described. The²⁸Al signal obtained upon neutron irradiation includes contributions from both the reaction²⁷Al(n,)²⁸Al and³¹P(n,)²⁸Al. The first reaction is with the thermal neutrons and the second one is with the fast neutrons. The contribution from the³¹P reaction is calculated from the fact that Ca/P ratio in bone mineral is constant and the amount of calcium can be measured from the thermal reaction⁴⁸Ca(n, )⁴⁹Ca. The aluminum values obtained by the INAA procedure agreed within 10% of those obtained by atomic absorption spectrophotometry. With this assay the levels of aluminum in normal bones (<70 g g^–1 apatite) cannot be determined reliably but higher aluminum levles in bone biopsies associated with Al toxicity, e.g. some patients with renal osteodystrophy, can be determined with a precision of ±10%.     

Neutron activation analysis for the routine clinical investigation of osteoporosis

Neutron activation analysis provides a useful clinical test to assess bone mass status in vivo. The neutron flux is obtained from Pu/Be sources and⁴⁹Ca activity is measured by NaI detectors. For diagnostic value, the⁴⁹Ca measurement is related to the mean value for normal subjects of the same body size. This normalized index, our CaBI, is used extensively to diagnose the bone loss associated with osteoporosis and to asses changes in bone mass with progression of disease and in response to treatments. Our facility operates at maximum capacity (35 tests/wk.). The hospital location and the dependability and ease of operation (provided by neutron sources) have facilitated extensive clinical use.     

From potential to reality: Yeasts derived from ethanol production for animal nutrition

A chemical and radiochemical neutron activation analysis (CNAA/RNAA) method has been developed for the determination of three calcium isotopes (⁴⁸Ca,⁴⁶Ca, and⁴⁴Ca) in a single sample derived from urine. This method was developed in support of clinical research using a dual enriched stable isotope methodology to study bone mineralization in premature infants, juvenile rheumatoid arthritics, and cystic fibrosis. In these studies, one enriched isotope of calcium is administered orally, and one is administered intravenously. By making determinations of three isotopes (two enriched, one unenriched) within the same sample, the perturbation from natural isotopic ratios can be determined and used to calculate true absorption of calcium. In our method,⁴⁸Ca is determined via the⁴⁸Ca(n,γ)⁴⁹Ca reaction and 3084 keV gamma-ray,⁴⁶Ca via the⁴⁶Ca(n,γ)⁴⁷Ca reaction and 1296 keV gamma-ray, and⁴⁴Ca via the⁴⁴Ca(n,γ)⁴⁵Ca reaction and 256 keV (max) beta-particle. A pair of chemical separation steps are employed to separate calcium from urine as calcium oxalate with a yield in the range of 80–90%, and a radiochemical step is employed prior to the measurement of⁴⁵Ca to remove interfering radionuclides.     

Determination of calcium,phosphorus and fluorine in bone by instrumental fast neutron activation analysis

The determination of fluorine, calcium and phosphorus in bone by instrumental fast neutron activation analysis is described. Results for the IAEA standard material “Animal Bone” A3-74 re: Ca=313±10 mg/g, P=155±5 mg/g and F-613±20μg/g. The accuracy for all three elements is≤4%, precision being about 3%. The limit of determination for F is 120 μg, for Ca 30 mg and for P 1 mg in a sample of 500 mg.     

Determination of Macro, Micro and Ultra Micro Concentration of Some Elements in Normal and Diseased Tissues of the Bone by NAA Employing 252Cf and Reactor Neutrons

A method has been developed for the determination of elements in normal and diseased tissues of the bone employing radiochemical and instrumental neutron activation analysis. Elements such as Na, Br, Au, Sb, Sc, Fe, Zn and Cr were subjected to irradiation in ²⁵²Cf or CIRUS reactor followed by measurement of the activity on a HPGe detector coupled to a PC based MCA unit. Elements such as Co, Ca and P were subjected to radiochemical separation prior to the measurement. The statistical evaluation with respect to accuracy and precision is discussed.     

Measurements of fluoride in bone biopsies by neutron activation analysis for the clinical study of osteoporosis

A procedure has been developed to measure fluoride concentration in bone biopsies by neutron activation analysis /NAA/. The NAA procedure is non-destructive so that the bone biopsies can be used subsequently for histological evaluation. The fluoride content is expressed as F/Ca ratio in the bone samples. The fluoride and calcium are measured using the reactions:¹⁹F/n, /²⁰F /t=11.2 s/ and⁴⁸Ca/n,/⁴⁹Ca/t=8.8 m/, respectively. The F/Ca ratio normalizes the fluoride to bone mineral avoiding the use of bone weight which is unreliable with fresh biopsy samples. This ratio also corrects for variations in neutron flux and gamma counting efficiencies. Results by this procedure were compared to biochemical determinations using an ion-selective electrode for fluoride and atomic absorption for calcium. The two methods gave results which agreed within ±5% which is the precision of the NNA procedure. The NAA method provides a simple and non-destructive procedure for fluoride measurement in bone biopsies for clinical studies. The method is now routinely used in our clinical studies for the fluoride measurements on biopsies from osteoporotic patients treated with fluoride therapy for nearly four years.     

In vivo neutron activation analysis of rats

A method of estimating total body calcium and sodium in rats by in vivo neutron activation analysis is described. The subjects were exposed to an integrated flux of about 1.6·10¹¹ thermal neutrons and activity was determined by counting with a 3″×3″ NaI(Tl) detector. The growth of the subjects was followed for about 75 days. The values of total body concentrations obtained are 0.83–0.90% for Ca and 0.128% for Na. Consideration is given to the accuracy attainable and to the effects on the blood and the hematopoietic tissues of the radiation doses imparted.     

The in vivo neutron activation analysis of calcium in the skeleton of normal subjects,with hypokinesia and bone diseases

A facility developed for the in-vivo neutron activation analysis (IVNAA) of calcium in some parts of tubular limb bones, in the hand, foot and spine is described. The⁴⁸Ca(n, )⁴⁹Ca reaction is used, the gamma-rays of⁴⁹Ca (E=3.08 MeV, T_1/2=8.8 min) are measured. The irradiation is carried out with five of ten²³⁸Pu–Be neutron sources with a source stength of 5·10⁷ n s^–1 each arranged in a bath filled with water. NaI(T1) detectors (from 2 to 4 in number) of 150×100 mm size supplied with lead and shadow shielding are used in the counting unit. The construction of the facility started in 1972 and has been in operation since 1974. It has been used for the examination of patients suffering from limb bone tumors, of children with rickets-like and similar diseases and for studies in space medicine.     

Determination of trace elements in water by non-destructive neutron activation

A systematic study was undertaken in order to find out which of the most relevant elements can be determined in water under normal conditions by non-destructive neutron activation simultaneously using a suitable monostandard method. Standardized water samples as well as natural water of different kind were used, brought to dryness by freeze-drying and irradiated in quartz at a neutron flux of 10¹⁴ cm⁻² s⁻¹ for 1 day. The trace element content in quartz ampoules of different origin was determined separately. The following elements are discussed in detail including possible interferences: As, Au, Br, Ca, Cd, Co, Cr, Cu, Eu, Fe, Hg, K, La, Mo, Na, Ni, Sb, Sc, Se, U, Zn. Presented at the Euroanalysis II Conference, Budapest, 25–30. Aug. 1975.     

Preliminary study of trace elements in human brain tumor tissues by instrumental neutron activation analysis

Elemental profiles of brain tumor tissues from 15 patients of astrocytomas (grade I–III) and normal human brain tissues of 23 male age matched autopsies as controls have been studied by instrumental neutron activation analysis. The SLOWPOKE reactor with a thermal neutron flux of 8·10¹¹n·cm^–2·s^–1 and swimming pool type reactor with a thermal neutron flux of 1·10¹³n·cm^–2·s^–1 were used for short and long irradiation of samples, respectively. Spectrophotometry was only used for analyzing phosphorus. A total of 18 elements Se, Na, K, Br, Cl, Mn, Mg, S, Ca, Cu, Hg, Cr, Fe, Rb, Zn, Co, Sc and P has been determined for this purpose. The reliability of methods has been checked by analyzing biological standard reference materials horse kidney (IAEA H-8) and bovine liver (NBS SRM 1577a). The analytical results showed that compared with the normal brain tissues, concentrations of Ca, Fe, Cu, Zn, Se, Mn, Br and Sc were significantly higher in tumor tissues (P<0.01) and concentrations of Rb, K and P were lower, while no differences for contents of Mg, S, Cr, Hg, Na and Cl were observed. A negative correlation between P and Ca in malignant and normal brain tissues was observed.     

The determination of fluorine in bones by non-destructive neutron activation analysis using 11.2 sec20F

A fast non-destructive determination of fluorine in bone samples by thermal neutron activation analysis using¹⁹F(n, γ)²⁰F reaction was developed. About 0.1–1 g samples is irradiated for 15 sec in TRIGA MARK II reactor at a thermal neutron flux of 5·10¹¹ n·cm⁻²·sec⁻¹. After 15–25 sec cooling, the 1633 KeV²⁰F activity (T=11.2 sec) is counted for 15 sec with a Ge(Li) spectrometer. A standard sample is prepared by mixing CaF₂ and CaCO₃ powders. The interference from²³Na(n, α)²⁰F is corrected by employing²⁴Na 2754 KeV double escape peak activities in samples and the²⁰F/²⁴Na peak area ratio observed previously for pure Na₂CO₃ powder. The precision is 7% for a bone sample containing 1020 ppm F and the sensitivity is about 10 ppm F.     

Instrumental neutron activation analysis of gunpowder residues

A procedure has been developed for the detection of gunpowder residues deposited on the hand of a person firing a gun. The method is based on neutron activation analysis of the antimony level on the surface of the hand. The surface materials are removed by a film made by spraying a 4% solution of cellulose acetate in acetone, which sets to form a thin film that can readily be stripped off. This technique was found to be preferable to the paraffin-lift technique which is in common use. Following neutron activation of the film in a nuclear reactor, antimony is assayed by high-resolution Ge(Li) spectrometry without prior chemical processing. The sensitivity of the method is about 5·10⁻⁹ g Sb, with a precision of about ±10% at a neutron flux of 5·10¹³ n·cm⁻²·sec⁻¹. Analysis of twenty samples taken from the hands of persons who had fired a pistol gave Sb levels of 0.4±0.2 μg, compared with 0.024±0.013 μg found on the hands of persons who had not fired a revolver. The possible extension of the present technique to include the determination of additional elements is discussed. Project carried out with the support of the Office of the Chief Scientist to the Ministry of Defense and with the collaboration of the Israel Police.     

In vitro activation of bone with 14 MeV neutrons

Samples of compact bone, bone marrow and spongiosa of cow femur have been irradiated in vitro with 14 MeV neutrons. The Ca/P ratio for compact bone was found to be 2.16±0.24. The suitability of using 14 MeV neutrons and the³¹P(n, α)²⁸Al reaction for studying the bone mineral composition in vitro is discussed.     

Determination of the ratio of calcium to phosphorus in foodstuffs by dynamic reaction cell inductively coupled plasma mass spectrometry

An inductively coupled plasma mass spectrometer (ICP–MS) equipped with a dynamic reaction cell (DRC) was used for the determination of Ca and P in foodstuffs. In this study, two different reaction gases, CH₄ and O₂, were introduced successively through the different channels to alleviate different interferences in the same analysis run. The effect of the operating conditions of the DRC system was studied to get the best signal-to-noise ratio for each element. The interfering ⁴⁰Ar⁺ at m/z 40 was reduced in intensity by up to five orders of magnitude by using 1.0 mL min^–1 CH₄ as reaction cell gas in the DRC. On the other hand, by using O₂ as the reaction gas, ³¹P⁺ was converted to ³¹P¹⁶O⁺ that could be detected at m/z 47 where there was less interference. The limits of detection for Ca and P were 0.2 ng mL^–1 and 0.3 ng mL^–1, respectively. This method was used to determine the concentrations of Ca and P and the ratio of Ca to P in NIST SRM 1549 non-fat milk powder and NIST RM 8345 whole milk powder reference materials and an infant milk powder and an infant cereal-rice sample purchased locally. The results for the reference samples agreed satisfactorily with the reference values. The accuracy of the determination was better than 4.1 and 0.9% for Ca and P, respectively. The results for infant milk powder and infant cereal were also found to be in good agreement with the value on the bottle label. Precision (RSD) between sample replicates was better than 4.8% for all the determinations.     

Proton-induced prompt gamma-ray emission for determination of light elements in human bone

Proton-induced prompt gamma-ray emission (PIGE) analysis has been used for the determination of light elements in human dense bone samples. Li, B, N, O, F, Na, Mg, Al, P and Ca peaks were detected. Smoothed, freeze-dried samples were irradiated in vacuo by 2.4 MeV protons and the induced prompt gamma rays recorded with a 110 cm³ Ge(Li) detector. Absolute concentrations were calculated on the basis of both calibration standards and pure element gamma-ray yields. The mean (±1 S. D.) concentrations as ppm or weight % obtained for 15 dense bone samples were: B 8.0 (3.3)ppm, N 12.2 (0.8)%, O 34.8 (2.3)%, F 639 (417)ppm, Na 5763 (371)ppm, Mg 2078 (290)ppm, P 9.26 (0.50)% and Ca 20.4 (1.3)%. The detection limits obtained without any prior concentration of the bone samples were: 0.3 ppm for Li, 2.0 ppm for B, 1.0% for N, 1.0% for O, 1.0 ppm for F, 3.0 ppm for Na, 50 ppm for Mg, 22 ppm for Al, 600 ppm for P and 0.8% for Ca. Detection limits for other light elements (4≤Z≤21) have also been estimated.     

Development of an irradiation/shielding cavity for in vivo neutron activation analysis of manganese in human bone

Summary Manganese is essential to human life for normal neurological and skeletal functions. Longstanding, excessive exposure to Mn compounds may result in manganism, a Parkinson's disease like syndrome. Prolonged exposure to Mn at low levels can result in memory deficit, loss of motor control and reduction in the refinement of certain bodily motions. A feasibility study of measuring Mn concentrations in human bone with in vivo neutron activation analysis (IVNAA) was previously reported.¹ Since then, an irradiation/shielding cavity, consisting of moderator, gamma-ray filter, neutron reflector, and shield walls, was constructed for the clinical application of Mn IVNAA,² and an upgraded IVNAA system is reported here. The minimum detectable limit is 0.081 mg in the hand, which is toward the lower end of the estimated bone Mn level of 0.065 to 1 mg in the hand of healthy subjects. A significantly lower radiation dose is delivered than in the reported feasibility study.     

In vivo iontophoretic delivery of calcium ions through guinea pig skin enhanced by direct and pulsating current

Studies were initiated to investigate the effect of the delivery mode of⁴⁵Ca ions through guinea pig skin in vivo. Direct current (DC), pulsating current (PC) and a Bernard current form, the “courtes periodes” current profile (CP) were applied with the same current density (0.16 mA/cm²) and for the same duration (30 minutes). The⁴⁵Ca ions were delivered from a Ca-bentonite patch radiolabeled with⁴⁵Ca (a natural mineral clay rich in calcium, 50 mgCa/g). The total quantity of applied bentonite was 1.5g×10 days=15g.⁴⁵Ca was counted in different biological samples of the animals. The delivery of⁴⁵Ca ions into the body (systemic effect) is the highest when CP current is applied (6.87±0.95·10⁻¹²g/samples). The local effect appears to be more effective in case of DC current mode (5.89±0.12·10⁻¹²g/0.5g bone). Total calcium measurements proved that the result of transdermal radiocalcium delivery is not only an ion exchange process at the surface of the bone but a deposition of calcium ions into the hydroxiapatite matrix (the net calcium introduction, which represent the difference between the total calcium into the treated bone and total calcium into untreated bone varied from 15.52±2.42·10⁻³g/0.5g bone to 44.30±3.50·10⁻³g/0.5g bone). The results suggest that iontophoresis could be used to accumulate calcium into different target tissues using the appropriate current system.     

Neutron activation analysis of uranium in human bone,drinking water and daily diet

Uranium in human bone, drinking water and daily diet has been determined by neutron activation analysis using the²³⁸U(n, γ)²³⁹U reaction. An improved scheme for the separation of the²³⁹U is proposed; with this scheme, after neutron irradiation in a 100 kW TRIGA reactor, a uranium content as low as 5·10⁻¹¹ g can be determined reliably, rapidly and easily. A wide range of uranium concentrations, from about 0.1 ppb up to about 10 ppb has been found in the bones of normal Japanese. Water from several Japanese city water services, and the daily diet taken in two Japanese cities, have been found to contain an average 9·10⁻⁹ g/l and 1.5 μg per person-day uranium, respectively.     

Small sample in-vivo neutron activation analysis using californium sources

This work describes an in vivo neutron activation analysis facility for small samples, such as rats or human hand, using two 100 g²⁵²Cf neutron sources. The irradiation area is a cylindrical space, of 12 cm diameter and about 15 cm length, with fairly uniform neutron flux distribution. Experimental data on the reproducibility, effects of volume and other conditions for in vivo measurements are given. Comparative atomic absorption data on calcium measurements on rats are reported. The facility is now used for animal experiments as well as human hand irradiations in clinical investigations involving calcium metabolism and bone diseases.     

Simultaneous determination of phosphorus-32 and calcium-45 activity in biological samples

Using the technique of liquid scintillation,³²P and⁴⁵Ca activites were determined in biological samples such as bones, blood, milk and egg shells, white and yolk. Samples were mineralized in 70% HClO₄ and 30% H₂O₂ at 70 °C and measured after addition of the “Aquasol” scintillation liquid. A correction for quenching was made by the method of sample channels ratio. High detection efficiencies were obtained, above 80% for⁴⁵Ca and about 50% for³²P in a second measuring channel. Recoveries amounted to 0.95–1.06 for³²P and to 0.93–0.98 for⁴⁵Ca.