Optimal use of instrumental neutron and photon activation analyses for multielement determinations in sewage sludges

A combination of instrumental neutron activation analysis (INAA) and instrumental photon activation analysis (IPAA) methods has been developed for multielement determinations in a variety of sludges and fertilizers. The precision and accuracy of both the methods have been evaluated by analyzing replicate samples, NBS standard reference materials, and an interlaboratory intercomparison sewage sludge sample. The concentration rages of up to 50 elements in raw and chemical sludges, sludge-based fertilizers, and other organic and inorganic fertilizers are reported here. The advantages and limitations of the INAA and IPAA methods are also discussed here.     

Comparison of microwave-assisted acid leaching techniques for the determination of heavy metals in sediments, soils, and sludges

Microwave-assisted EPA method 3051 for nitric acid leaching of environmentally key elements from sediments, soils, and sludges was tested, and the influence of leaching temperature and time on element recovery for an estuarine sediment (CRM 277) was investigated. The extraction efficiencies for four certified reference materials applying EPA method 3051, an optimized nitric acid procedure, and an aqua regia (HCl/HNO₃ 3:1) procedure were compared. Digestions were carried out in a high-pressure microwave system offering simultaneous temperature and pressure control for all digestion vessels employed. Eight elements (Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn) were determined by ICP-AES and ICP-MS. Extraction efficiency strongly depended on the applied leaching parameters and varied for certain elements among different materials when a nitric acid procedure was applied. In general, element recoveries obtained from the aqua regia procedure were superior to those obtained from nitric acid procedures and showed good agreement with the 95% confidence interval of the certified value for most of the elements investigated. Received: 27 March 1998 / Revised: 29 June 1998 / Accepted: 3 July 1998     

Instrumental neutron activation analysis for quality assurance of a hair reference material for mercury speciation

Instrumental neutron activation analysis (INAA) has been employed in the investigation of mass balance for mercury species analysis in the analytical process. A new human hair reference material (IAEA-085) was analyzed for methylmercury using a solid/liquid extraction procedure, with samples of extracts, residues, and untreated samples being analyzed by INAA. The certified reference material NIES CRM No. 13, human hair, was analyzed in parallel. From the results obtained through the mass balance studies, it was found that the extraction procedure was quantitatively complete, and that there was no difference between the mass balance of Hg and the total Hg in the untreated materials.     

Application of the INAA methods for KRISS infant formula CRM analysis: standardization of INAA at KRISS

We have established an instrumental neutron activation analysis (INAA) method, including k₀-based INAA, at the Korea Research Institute of Standards and Science (KRISS) for the certification of reference materials. As part of establishing INAA measurements, KRISS infant formula certified reference material was analysed for multiple elements at three different metrological institutes: KRISS and NIST for the standard comparator method, and JSI for the k₀-INAA method. The mass fraction of most elements was consistent within expanded uncertainty (k?=?2). In addition, the results were used to verify the validity of elemental analysis of Zn using the standard comparator INAA at KRISS, and spreadsheet-based INAA calculations were evaluated.

     

A comparison between INAA and ICP-MS for the determination of element concentrations in marine sediments

In this study, instrumental neutron activation analysis (INAA) and inductively coupled plasma-mass spectrometry (ICP-MS) were used to compare results obtained by both techniques for sediment samples collected from the Patras Harbour, Western Greece. The accuracy of the methods was tested using reference materials. In total seven elements were measured by both techniques (Zn, Ni, Cr, Ba, As, U, Co). Results obtained by ICP-MS were compared with those obtained by INAA by applying paired t-test. Insignificant differences in mean concentration values were found for Zn, Ni, Cr and Ba, whereas the differences for As, Co and U were significant. Correlations between element concentrations measured by both techniques are also discussed.     

Use of INAA in the preparation of a set of soil reference materials with certified values of total element contents

A set of certified Reference Materials was prepared consisting of four natural agricultural soils with normal (n) and elevated (e) levels of element contents: CRM 7001 Light Sandy Soil (n), CRM 7002 Light Sandy Soil (e), CRM 7003 Silty Clay Loam (n), and CRM 7004 Loam (e). In these materials, certified and/or information values of the total contents of the elements As, Ba, Be, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, V and Zn, and their fractions extractable by aqua regia, boiling and cold 2M nitric acid were derived from an interlaboratory comparison in which 28 laboratories participated. Highly precise and accurate procedures of instrumental neutron activation analysis (INAA) were employed for homogeneity testing and also for certification of the total element contents. For comparation purposes, NIST SRM-2704 Buffalo River Sediment was analyzed by INAA, as well. The INAA results obtained compared very well with the certified and/or information values for four soil CRMs and also with NIST values for SRM-2704. From this agreement, a very high reliability of the new soil CRMs can be inferred.     

Establishing a basis for nuclear archaeometry in Australia using the 20 MW OPAL research reactor

The k ₀-method of standardisation for instrumental neutron activation analysis (INAA) has been used at the OPAL research reactor to determine the elemental composition of three certified reference materials: coal fly ash (SRM 1633b), brick clay (SRM 679) and Montana soil (SRM 2711). Of the 41 certified elements in the three materials, 88 percent were within five percent of the certified values and all determinations were within 15 percent of the certified values. The average difference between the measured and certified values was 0.1 percent, with a standard deviation of 4.1 percent. Since these reference materials are widely used as standards in the analysis of archaeological ceramics by INAA, it has been concluded that the INAA facility in Australia is particularly well-suited for nuclear archaeometry.     

Determination of aluminium contents in selected food samples by instrumental neutron activation analysis

Food and food products are the main sources of Aluminium entering the human body. In order to know aluminium contents in food and food products, selected 26 samples from local market were analyzed by instrumental neutron activation analysis (INAA) using reactor neutrons and high resolution gamma-ray spectrometry. INAA using 1,779 keV γ-ray of ²⁸Al (2.24 min) was used for aluminium concentrations in the range of 33–529 mg kg^?1. Two NIST standard reference materials (SRMs) and two IAEA reference materials (RMs) were analyzed by INAA for quantification of aluminium as a part of method validation.     

Metrological role of neutron activation analysis. IA. Inherent characteristics of relative INAA as a primary ratio method of measurement

In a series of three papers, the inherent characteristics of relative instrumental neutron activation analysis (INAA) as a primary ratio method of measurement, the unique functions of parametric INAA as an ideal back-up method of the relative INAA, and the valuable role of INAA in characterization of sampling behavior of individual elements in certified reference materials (CRMs) will be discussed. In this paper, the first of the series, the uncertainty evaluation and the traceability of values measured by neutron activation analysis (NAA), especially instrumental NAA (INAA), will be described to demonstrate the method at its ”the state-of-the-art” level can meet CCQM criteria for a primary ratio method. The scope and examples will be given. Received: 19 March 2001 Accepted: 2 October 2001     

INAA and PIXE for the determination of the contents of extractable sediment

The three-stage BCR sequential step reference extraction procedure was applied to the reference material BCR CRM 601, especially developed for fractionation studies. Extracted fractions were analyzed for Cr, Ni, Zn, Cd, and Pb, by k ₀-standardized instrumental neutron activation (k ₀ INAA) and proton induced X-ray emission (PIXE), and flame atomic absorption spectrometry (FAAS). Sample preparation procedures were developed for both k ₀ INAA and PIXE techniques, related to the evaporation of the solutions in order to get solid samples for neutron and proton irradiation. Quality control was assessed by intercomparison of the analytical results obtained by the applied techniques, which included results for a few certified reference materials. In the extracted fractions, chromium concentration was not determined accurately by both nuclear techniques. Concerning Cd, Ni, Pb, and Zn, the results were in general in good agreement with the certified values and FAAS. Some incomplete separation of the residue might have occurred.     

Elemental analysis of leaves and extracts of Casearia medicinal plants by instrumental neutron activation analysis

Summary Instrumental neutron activation analysis (INAA) was applied to determine the inorganic composition of leaves and extracts from three different species of Casearia genus plant (C. sylvestris, C. decandra and C. obliqua). Statistical analysis of the analytical data of leaf showed that the three Casearia species present similar elemental composition. Extract from C. sylvestris showed significantly different inorganic content in comparison with the two other species. Certified reference material NIST SRM-1515 Apple Leaves was analyzed for quality control.     

Multielement Analysis of Iliac Crest Bone by Neutron Activation

The k ₁-method for standardization in INAA specifically tackles the problem of the interpretation of gamma-ray spectra as obtained with highly efficient detectors, as opposed to the k ₀-method. In this paper, results obtained from three NIST reference materials, measured after neutron activation with a gold-lined well-type detector, are presented. It is concluded that the accuracy of the method is better than 1%.     

A new neutron activation technique for simultaneous determination of inorganic and total mercury contents in human hair

A simple method for simultaneous determination of inorganic and total mercury contents in human hair by neutron activation analysis (NAA) has been developed. The method is based on the selective extraction of methylmercury from hair by hydrochloric acid. Thus, the residual phase containing inorganic mercury can be determined by NAA. Further, the methylmercury contents in hair samples are easily calculated by subtracting the inorganic mercury contribution from the total Hg simultaneously given by INAA. Several reference materials of human hair, including IAEA hair RM 085 and 086, Chinese hair RMs GBW 09101 and 07601, were analyzed by this method. Our results show that the method is reliable.     

NAA methods for determination of nanogram amounts of arsenic in biological samples

Summary The determination of arsenic at natural levels in biological materials remains difficult. Many analytical techniques cannot detect the low levels present in typical biological tissues and other techniques suffer from interferences. This paper reviews uses of neutron activation analysis (NAA) at NIST to determine nanogram amounts of arsenic in biological reference materials with radiochemical (RNAA) or instrumental (INAA) procedures. INAA is compromised by high activities from ²⁴Na, ⁸²Br, and ³²P that may be formed during irradiation of biological tissues, and result in detection limits as high as 0.1 mg. Lower detection limits have been achieved using state-of-the-art gamma-ray spectrometry systems in INAA and a variety of procedures in RNAA. These techniques and procedures were applied recently at NIST to the determination of arsenic in urine, nutritional supplements, and total diet samples.     

Intercomparison of moss reference material by different multi-element techniques

An intercomparison of data obtained for a moss reference material (Hylocomium splendens) used as biomonitor of atmospheric deposition by different multi-element techniques is presented. In total 43 elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Zr, Ag, Sn, Sb, I, Cs, Ba, La, Ce, Nd, Sm, Eu, Gd, Tb, Tm, Yb, Lu, Hf, Ta, W, Au, Th, U) were determined using inductively coupled plasma-mass spectrometry (ICP-MS), conventional instrumental neutron activation analysis (INAA), epithermal neutron activation analysis (ENAA) and as well as shorttime neutron activation analysis without and with a⁶LiD-converter. Advantages and drawbacks of each method are discussed. The introduction of moss reference materials for atmospheric multi-element deposition studies involving nuclear analytical techniques is strongly recommended.     

Determination of mercury and organic mercury contents in Malaysian seafood

The contents of mercury and organic mercury in various types of seafood from various location in Malaysia were determined by neutron activation analysis. Total mercury was determined by instrumental neutron activation analysis (INAA) whilst organic mercury was determined by INAA after chemical separation. Samples were digested in acid media and into the solution was added copper ion and KBr to release organic mercury compound from sulphur component of the tissue. The organic mercury was then extracted into toluene and then treated with cysteine paper to convert the compound into sub-organo-mercury from. The paper was then transferred into polyethylene vials and irradiated in the MINT TRIGA Reactor. Analytical results of organic mercury in Indian mackerel (Rastrelliger kanagurta), Spanish mackerel (Scomberomurus commersoni), shrimp (Peneaus sp.), squid (Loligo sp.) and cockle (Anadara granosa) is in the range of 45%–94% of the total mercury.     

Primary standards in activation analysis

The availability of natural matrix reference materials evaluated for trace element content has resulted in their widespread use as standards (i.e., calibration materials; comparators) for instrumental neutron activation analysis (INAA). Due to the uncertainties associated with their certified values, the limited number available, and the relative matrix independence of INAA, these reference materials are more properly utilized as quality assessment materials, after calibration of the INAA analytical system with true primary standards. Terminology is defined, the use of matrix reference materials to evaluate the analytical system is discussed, techniques for the accurate preparation of primary standards for trace element analyses are reviewed, and necessary precautions in the accurate comparison of samples to standards are presented.     

Development and Validation of an Analytical Method for Determination of Al,Ca, Cd,Fe, Mg and P in Calcium-Rich Materials by ICP OES

Four procedures based on closed-vessel microwave-assisted wet digestion with different oxidative reagents, including HNO₃ (P1), HNO₃ + H₂O₂ (P2), aqua regia (P3) and Lefort aqua regia (P4), for preparation of calcium (Ca)-rich materials prior to determination of total concentrations of Al, Ca, Cd, Fe, Mg and P by inductively coupled optical emission spectrometry (ICP OES) were compared. It was found that digestion with Lefort aqua regia (P4) provided the best results for all examined elements, i.e., precision of 0.30–4.4%, trueness better than 2%, recoveries of added elements between 99.5–101.9%, and limits of detection within 0.08–1.8 ng g⁻¹. Reliability of this procedure was verified by analysis of relevant certified reference materials (CRMs), i.e., Natural Moroccan Phosphate Rock—Phosphorite (BCR-O32). Additionally, selection of appropriate analytical lines for measurements of element concentrations, linear dynamic ranges of calibration curves and matrix effects on the analyte response were extensively investigated. Finally, the selected procedure was successfully applied for routine analysis of other Ca-rich materials, i.e., CRMs such as NIST 1400 (Bone Ash), CTA-AC-1 (Apatite Concentrate Kola Peninsula) and NCS DC70308 (Carbonate Rock), and six natural samples, such as a dolomite, a phosphate rock, an enriched superphosphate fertilizer, pork bones, pork bones after incineration, and after steam gasification.     

Profile of selenium in soil and crops in seleniferous area of Punjab,India by neutron activation analysis

In the Nawanshahr–Hoshiarpur region of Punjab, India, more than 1000 hectares of agricultural land is significantly affected by high levels of selenium (Se). Studies were carried out to examine Se levels in soil and crops such as wheat grains, wheat husk, rice, maize and mustard using neutron activation analysis. The Se concentrations in soil and crop products were found to be ranging from 2.7 to 6.5 mg kg⁻¹ and 13 to 670 mg kg⁻¹, respectively, indicating significantly high selenium in these crop products. Two reference materials were analysed for Se contents by INAA as controls.     

INAA with anticoincidence counting significantly reduces interferences from the 554.3-keV photopeak of <Superscript>82</Superscript>Br to allow reliable measurements of nanogram levels of arsenic in solid biological materials via the 559.1-keV photopeak of <Superscript>76</Superscript>As

It is rather difficult to measure low levels of arsenic by instrumental neutron activation analysis (INAA) in biological materials containing high levels of bromine and antimony in particular, as well as sodium and potassium. The 559.1-keV photopeak of ⁷⁶As is interfered with by the 554.3- and 564.1-keV photopeaks of ⁸²Br and ¹²²Sb, respectively. The use of INAA in conjunction with anticoincidence spectrometry (INAA-AC) was found to reduce the background under the 559.1-keV photopeak by factors of 4–16 for the biological reference materials analyzed and to decrease the detection limit to 0.35 µg kg^?1 making the measurement of nanogram amounts arsenic in them possible.