Biological Standard Reference Materials Research Articles

Comprehensive two-dimensional gas chromatography high-resolution mass spectrometry for the analysis of substituted and unsubstituted polycyclic aromatic compounds in environmental samples

Polycyclic aromatic compounds (PACs) consists of multiple compounds and the number of theoretically possible isomers can reach into the thousands. Currently each PAC group is quantified collectively as a single group of compounds. However, individual PACs can reveal important information on how the PACs were formed and this information may be used to determine sources of PACs in environmental samples, It is hypothesized that many of the limitations with characterizing alkylated PACs with one dimensional gas-chromatography (1D GC) can be circumvented using GC × GC (two dimensional gas chromatography). Here we apply comprehensive GCxGC coupled to high-resolution time of flight mass spectrometry (GC × GC-HFTOF-MS) to aid in the separation, identification and quantitation of APACs in three environmental matrices: mussel tissue (Mytilus edulis), lubricating oil and coal. In the absence of authentic analytical standards, differences in the mass spectral fragmentation pattern of isomers were used to confirm the identity of isomers within a PAC group. The method was validated according to the EURACHEM guidelines and used to quantify a biological standard reference material (SRM 2974a). The method met all the standard method performance requirements such as trueness, precision and measurement of uncertainty and is fit for quantifying these compounds in biota. Furthermore, the method was used to identify and quantify additional PAC compounds in the SRM 2974a material which to date have not been certified. With appropriate statistical analytical tools, the described GC × GC method can be used as a tool for more robust source fingerprinting and source apportionment of PACs in the environment.

Determination of selenium in biological materials by short-time neutron activation analysis using ⁷⁷ᵐSe at the Dalat research reactor

A rapid neutron activation analysis technique for determination of the concentration of selenium in biological materials using short-lived radionuclide 77mSe (half-life = 17.4 seconds) has been developed at Dalat Nuclear Research Institute (DNRI). The technique is very simple and rapid. It involves irradiation of a sample for 20 s, decay for 20 s and counting for 20 s. The accuracy of the method has been evaluated by analyzing a number of biological standard reference materials of varied selenium levels. An agreement between measured and certified values was acceptable in regarding to the deviation of the above mentioned two values within 8 percent. The result shows that the utilization of short-lived radionuclide 77mSe is more useful in comparison with long-lived radionuclide 75Se (half-life = 120 days). In addition, it is suggested that a further study for cyclic irradiations should be done in order to enhance the detection limit of the determination of the short-lived radionuclide 77mSe.

Determination of perfluorinated alkyl acid concentrations in biological standard reference materials

Standard reference materials (SRMs) are homogeneous, well-characterized materials used to validate measurements and improve the quality of analytical data. The National Institute of Standards and Technology (NIST) has a wide range of SRMs that have mass fraction values assigned for legacy pollutants. These SRMs can also serve as test materials for method development, method validation, and measurement for contaminants of emerging concern. Because inter-laboratory comparison studies have revealed substantial variability of measurements of perfluoroalkyl acids (PFAAs), future analytical measurements will benefit from determination of consensus values for PFAAs in SRMs to provide a means to demonstrate method-specific performance. To that end, NIST, in collaboration with other groups, has been measuring concentrations of PFAAs in a variety of SRMs. Here we report levels of PFAAs and perfluorooctane sulfonamide (PFOSA) determined in four biological SRMs: fish tissue (SRM 1946 Lake Superior Fish Tissue, SRM 1947 Lake Michigan Fish Tissue), bovine liver (SRM 1577c), and mussel tissue (SRM 2974a). We also report concentrations for three in-house quality-control materials: beluga whale liver, pygmy sperm whale liver, and white-sided dolphin liver. Measurements in SRMs show an array of PFAAs, with perfluorooctane sulfonate (PFOS) being the most frequently detected. Reference and information values are reported for PFAAs measured in these biological SRMs.

Highly sensitive and interference-free determination of bismuth in environmental samples by electrothermal vaporization atomic fluorescence spectrometry after hydride trapping on iridium-coated tungsten coil

Bismuthine was on-line trapped on tungsten coil and subsequently electrothermally vaporized for the determination by atomic fluorescence spectrometry (AFS). Several noble metals, including Pd, Rh, Pt, and Ir, were explored as permanent chemical modifier for tungsten coil on-line trapping. Investigation showed that Ir gave the best performance, in which bismuthine was on-line trapped on Ir-coated tungsten coil at 560 °C, and then released at 1550 °C for subsequent transfer to AFS by a mixture of Ar and H 2. Under optimum instrumental conditions, the trapping efficiency was found to be 73 ± 3%. With 120 s (12 mL sample volume) trapping time, a limit of detection (LOD) of 4 ng L − 1 was obtained, compared to conventional hydride generation AFS (0.09 μg L − 1 ); the LOD can be lowered down to 1 ng L − 1 by increasing the trapping time to 480 s. The LOD was found to be better or at least comparable to literature levels involving on-line trapping and some other sophisticated instrumental methods such as ICP-MS and GF-AAS. A comprehensive interference study involving conventional hydride-forming elements and some transition metals was carried out, and the result showed that the gas phase interference from other hydride-forming elements was largely reduced, thanks to the use of on-line tungsten coil trapping. Finally, the proposed method was applied to the determination of bismuth in several biological and environmental standard reference materials, and a t-test shows that the analytical results by the proposed method have no significant difference from the certified values at the confidence level of 95%.

On-line preconcentration using a resin functionalized with 3,4-dihydroxybenzoic acid for the determination of trace elements in biological samples by thermospray flame furnace atomic absorption spectrometry

In the present paper, an on-line preconcentration procedure for determination of cadmium, copper and zinc by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) is proposed. Amberlite XAD-4 functionalized with 3,4-dihydroxybenzoic acid (XAD4-DHB) packed in a minicolumn was used as sorbent material. The metals were retained on the XAD-DHB resin, from which it could be eluted directly to the thermospray flame furnace system. The detection limits were 28 (Cd), 100 (Cu) and 77 ng L −1 (Zn) for 60 s preconcentration time, at a sample flow rate of 7.0 mL min −1. Enrichment factors were 102, 91 and 62, for cadmium, copper and zinc, respectively. The procedure has been applied successfully to metal determination in biological standard reference materials.

Consideration and influence of complexed forms of mercury species on the reactivity patterns determined by speciated isotope dilution model approaches: A case for natural biological reference materials

The processes driving the inadvertent transformations of inorganic mercury (iHg) and methylmercury (MeHg) in cryogenically homogenized fresh-frozen (FF) and freeze-dried (FD) biological standard reference materials (SRM) were investigated using alkaline digestion, derivatization and gas chromatography inductively coupled plasma mass spectrometry (GC-ICP-MS). Labile inorganic mercury (201iHg) and methylmercury (Me202Hg) isotopic standards and their cysteine-complexed analogs (201Hg(Cys)2 and Me202HgCys) were used in a double-spike speciated isotope dilution (SID) model to document the influence of complexing ligands on the equilibration, the reactivity and the transformation processes between isotopic mercury species and their endogenous analogs. Cysteine-complexed and labile Me202Hg spiking standards displayed similar equilibration processes in both classes of materials, leading to accurate MeHg determinations with negligible methylation transformations. Labile 201iHg standards provided accurate iHg concentration results in both material series, although an apparent demethylation reaction specific of FF materials was detected, with a negligible effect in FD materials. Cysteine-complexed 201iHg standards led to higher but inaccurate iHg concentrations and higher demethylation yields in both materials. This comparison illustrated a significant influence of complexing ligands on the equilibration processes between labile and/or complexed 201iHg species and their endogenous analogs. The derivatization step was found to catalyze these non-equilibrium conditions with different derivatization yields between labile and complexed iHg species, whereas no differences were observed for MeHg species. When complexation disparities existed in solution between 201iHg species and their endogenous analogs, this process specifically affected the determination of 200/201iHg ratios relative to 200/202iHg, 200/201MeHg and 200/202iHg ratios, which are all involved in the double-spike SID model to establish transformation yields and mercury species concentrations. This process and the influence of demethylating agents were presumably responsible for the apparent demethylation reaction only observed in FF materials. This result gave rise to several questions on the influence of freeze-drying procedures on the lability/complexation patterns of mercury species and/or on the activity of demethylating agents. A complementary analytical step consisting of maximizing the equilibrium conditions between isotopic and endogenous mercury species together with inhibiting the activity of demethylating agent is proposed. When applying these conditions, the two classes of materials displayed negligible transformation reactions, improving their commutability for the simultaneous determination of iHg and MeHg. The approach proposed in this work allowed for the first time documentation of the potential and limitations of speciated isotope dilution procedures to handle the problem of lability/complexation and ligand interactions in natural biological matrices when considering multiple-spike SID approaches.

Simultaneous determination of inorganic mercury, methylmercury, and total mercury concentrations in cryogenic fresh-frozen and freeze-dried biological reference materials

Two speciated isotope dilution (SID) approaches consisting of a single-spike (SS) method and a double-spike (DS) method including a reaction/transformation model for the correction of inadvertent transformations affecting mercury species were compared in terms of accuracy, method performance, and robustness for the simultaneous determination of methylmercury (MeHg), inorganic mercury (iHg), and total mercury (HgT) concentrations in five biological Standard Reference Materials (SRMs). The SRMs consisted of oyster and mussel tissue materials displaying different mercury species concentration levels and different textural/matrix properties including freeze-dried (FD) materials (SRMs 1566b, 2976, and 2977) and cryogenically prepared and stored fresh-frozen (FF) materials (SRMs 1974a, 1974b). Each sample was spiked with (201)iHg (Oak Ridge National Laboratory, ORNL) and Me(202)Hg (Institute for Reference Materials and Measurements. IRMM-670) solutions and analyzed using alkaline microwave digestion, ethylation, and gas chromatography inductively coupled plasma mass spectrometry (GC/ICP-MS). The results obtained by the SS-SID method suggested that FF and FD materials are not always commutable for the simultaneous determination of iHg, MeHg, and HgT, due to potential transformation reactions resulting probably from the methodology and/or from the textural/matrix properties of the materials. These transformations can occasionally significantly affect mercury species concentration results obtained by SS-SID, depending on the species investigated and the materials considered. The results obtained by the DS-SID method indicated that the two classes of materials were commutable. The simultaneous and corrected concentrations of iHg, MeHg, and HgT obtained by this technique were not found to be statistically different form the certified and reference concentration together with their expanded uncertainty budgets for the five SRMs investigated, exemplifying the robustness, the accuracy, and the improved commutability of this method compared to SS-SID measurements.

New Developments in Standard Reference Materials (SRMs) for Environmental Forensics

For nearly three decades the National Institute of Standards and Technology (Gaithersburg, MD) has been involved in the development of Standard Reference Materials (SRMs) for the determination of organic contaminants in environmental matrices. Classes of organic contaminants characterized in these materials include polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), chlorinated pesticides, and most recently, brominated flame retardants (polybrominated diphenyl ethers [PBDEs]). Environmental matrices include fossil fuels, air and diesel particulate matter, house dust, coal tar, sediment, mussel and fish tissue, fish oil, and whale blubber. Recent SRM developments and activities have led to a number of environmental SRMs that are useful for assuring quality of analytical measurements in environmental forensics where source profiling of organic contaminants is often conducted in a range of environmental or biological matrices. Particle-related SRM developments include the issue of a new house dust material (SRM 2585 Organic Contaminants in House Dust), and the recertification of two SRMs: a diesel particulate matter material (SRM 1650b Diesel Particulate Matter) for certified and reference values for 97 PAHs and nitro-PAHs and a river sediment (SRM 1939b PCBs in River Sediment A) for a greater number of PCB congener concentrations relative to its former certification in 1998 as well as for total PCBs. A coal tar SRM (SRM 1597a Complex Mixture of PAHs from Coal Tar) has also been reissued with an expanded range of values for PAHs (including methyl- and dimethyl-substituted PAHs, PAH isomers of molecular mass 302, and polycyclic aromatic sulfur heterocycles [PASH]). The latest biological SRM developments include the issue of a new fish tissue SRM (SRM 1947 Lake Michigan Fish Tissue) and the recertification of a cod liver oil (SRM 1588b Organics in Cod Liver Oil) and a human serum (SRM 1589b PCBs, Pesticides, PBDEs, and Dioxins/Furans in Human Serum). SRM 1588b has values assigned for 124 constituents, and SRM 1589b has values assigned for 88 constituents. An overview of these recent SRM activities is provided in this paper, and selected organic contaminant values in newly developed particulate-related and biological SRMs are presented. The usefulness of these materials for assuring quality in environmental forensic measurements is also discussed.

Certification of methylmercury content in two fresh-frozen reference materials: SRM 1947 Lake Michigan fish tissue and SRM 1974b organics in mussel tissue (Mytilus edulis)

This paper describes the development of two independent analytical methods for the extraction and quantification of methylmercury from marine biota. The procedures involve microwave extraction, followed by derivatization and either headspace solid-phase microextraction (SPME) with a polydimethylsiloxane (PDMS)-coated silica fiber or back-extraction into iso-octane. The identification and quantification of the extracted compounds is carried out by capillary gas chromatography/mass spectrometric (GC/MS) and inductively coupled plasma mass spectrometric (GC/ICP-MS) detection. Both methods were validated for the determination of methylmercury (MeHg) concentrations in a variety of biological standard reference materials (SRMs) including fresh-frozen tissue homogenates of SRM 1946 Lake Superior fish tissue and SRM 1974a organics in mussel tissue (Mytilus edulis) and then applied to the certification effort of SRM 1947 Lake Michigan fish tissue and SRM 1974b organics in mussel tissue (Mytilus edulis). While past certifications of methylmercury in tissue SRMs have been based on two independent methods from the National Institute of Standards and Technology (NIST) and participating laboratories, the methods described within provide improved protocols and will allow future certification efforts to be based on at least two independent analytical methods within NIST.

Determination of trace elements in human gallstone and bile by k0-INAA

The trace elements composition of gallbladder stones samples of the types cholesterol, pigment and mixed stones in addition to bile have been investigated by k0-instrumental neutron activation analysis (k0-INAA). The samples were obtained from several individuals of adult subjects of the Libyan population who undergone open surgery of gallbladder (cholecystectomy) at Al-khadra University Hospital in Tripoli. The samples were lyophilized, irradiated together with Au wire and Zr foil, which serve as flux ratio monitor and a parameter at TNRC. Concentrations of 24 elements in gallstone and 23 elements in bile were determined. The levels of the trace elements in the various samples investigated are measured and discussed. The reliability of the analysis was checked with several biological standard reference materials.

Reflections on 35 years of biological SRM production and analyses

During the author's 39 years with the National Bureau of Standards (NBS)/National Institute for Standards and Technology (NIST) as an employee, and since then as Guest Researcher, he has been intimately involved with biological Standard Reference Material (SRM) production and analyses. His involvement with biological reference materials started with the very first biological certified reference material (CRM), the SRM 1571, Orchard Leaves, initiated in 1968 and issued in 1971, through the latest material (SRM 1575a, Pine Needles - renewal), issued in 2003. In addition, for more than 20 years he was Technical Coordinator for botanical SRMs for the NBS/NIST Analytical Chemistry Division. This paper contains his historical reflections and highlights from those years, and includes the techniques used to obtain and process these materials, new developments and procedures that resulted in vastly improved reference materials, the application of high accuracy neutron activation analysis to the certification of these standards, and the trace element quality assurance vital to the accuracy of these standards.

Arsenic extraction in marine biological materials using pressurised liquid extraction

A pressurised liquid extraction (PLE) procedure, by using methanol/water mixture, was developed for extracting arsenical species from marine biological material (mussel and fish) and standard reference materials (CRMs). A Plackett–Burman 2 8 × 3/64 designs (PBD) was used as a multivariate strategy for the evaluation of the effects of several variables (MeOH/H 2O solvent mixture, temperature, static time, extraction steps, pressure, mean particle size and diatomaceous earth (DE) mass/sample mass ratio) on the extracting procedure. Electrothermal atomic absorption spectrometry (ETAAS) was used to determine the total As concentration on the methanolic extracts. The accuracy of the optimised extraction procedure was verified by analysing several CRMs (GBW-08751, BCR-278R and DORM-2). The precision obtained (between 4.5 and 6.2%) was adequate. The extracted arsenic species (mainly arsenobetaine (AsB)) were analysed by high performance liquid chromatography coupled to ultraviolet cracking and hydride generation-atomic fluorescence spectrometry (HPLC–UV-HG-AFS). The analytical performances obtained were adequate for the arsenic speciation in marine biological samples; LOD between 10 and 35 ng g −1. The accuracy was verified for AsB using DORM-2. Finally, the proposed method (PLE followed by HPLC–UV-HG-AFS) was applied to mussel and fish samples.

Determination of iodine in human brain by epithermal and radiochemical neutron activation analysis

Despite the role of iodine for proper development of the brain and the functions of the element, the accurate data on its concentration in brain tissue are largely lacking, the main reason being analytical difficulties associated with determination of the element especially at low levels. In this work, samples from human brain regions from Hungarian patients were analyzed using epithermal and radiochemical neutron activation analysis (ENAA and RNAA, respectively). The RNAA procedure is based on alkaline–oxidative fusion followed by extraction of elemental iodine in chloroform. The results were checked by the analysis of biological standard reference materials, namely bovine liver, bone meal and diet, and by comparison with previous results obtained by a different RNAA procedure.

Brain aluminum, magnesium and phosphorus contents of control and Alzheimer-diseased patients

A study was undertaken to determine Al, Mg and P concentrations in 5 different brain regions of 3 control and 3 Alzheimer-diseased patients. One of the aims of this work was to evaluate the performance of applied analytical techniques. The digested samples were analyzed by inductively coupled plasma atomic emission spectrometry for Al, Mg and P. The dried samples were measured by instrumental neutron activation analysis for Al and Mg. The determination of human brain Al levels is complicated by the interfering reaction of P. We have previously worked out an analytical method which can eliminate this interference. The accuracy of the measured data was investigated by the analysis of biological standard reference materials. Our second goal was to study the possible elemental concentration changes in Alzheimer-diseased patients. Significantly higher Al and lower Mg and P values were found in some AD brain regions compared to the controls.

Gas chromatographic quantification of fatty acid methyl esters: Flame ionization detection vs. Electron impact mass spectrometry

The determination of FAME by GC is among the most commonplace analyses in lipid research. Quantification of FAME by GC with FID has been effectively performed for some time, whereas detection with MS has been used chiefly for qualitative analysis of FAME. Nonetheless, the sensitivity and selectivity of MS methods advocate a quantitative role for GC-MS in FAME analysis-an approach that would be particularly advantageous for FAME determination in complex biological samples, where spectrometric confirmation of analytes is advisable. To assess the utility of GC-MS methods for FAME quantification, a comparative study of GC-FID and GC-MS methods has been conducted. FAME in prepared solutions as well as a biological standard reference material were analyzed by GC-FID and GC-MS methods using both ion trap and quadrupole MS systems. Quantification by MS, based on total ion counts and processing of selected ions, was investigated for FAME ionized by electron impact. Instrument precision, detection limits, calibration behavior, and response factors were investigated for each approach, and quantitative results obtained by each technique were compared. Although there were a number of characteristic differences between the MS methods and FID with respect to FAME analysis, the quantitative performance of GC-MS compared satisfactorily with that of GC-FID. The capacity to combine spectrometric examination and quantitative determination advances GC-MS as a powerful alternative to GC-FID for FAME analysis.

Online flow digestion of biological and environmental samples for inductively coupled plasma–optical emission spectroscopy (ICP–OES)

A novel type of interface for gas removal has been developed for coupling a high-temperature/high-pressure online flow digestion system to an ICP spectrometry instrument. It consists of a porous polypropylene tube with an inner rod made of PEEK which causes the formation of a thin film (100 μm) of liquid at the inner surface of the porous tube, thereby considerably increasing the ratio of gas exchange area to liquid volume and simultaneously decreasing the dead volume. Thus very efficient removal of the gaseous reaction products, such as CO 2 and NO x , which are known to affect the ICP stability, was achieved. Even at high flow rates and with a high carbon content in the samples more than 99% of the gases were removed. Applying ICP–OES detection excellent recoveries were obtained for most elements except for Sb, Ag and Ga. Good agreement between certified and measured values was obtained for online determinations of elements in various biological and environmental standard reference materials. Low standard deviation and detection limits in the lower μg/g range were found. This new tube interface combines low costs with robust properties, compact design and ease of handling.

An accurate and sensitive method for the determination of methylmercury in biological specimens using GC-ICP-MS with solid phase microextraction

A highly sensitive and selective method has been developed for the determination of methylmercury in biological specimens and NIST Standard Reference Materials (SRMs). The procedure involves microwave extraction with acetic acid, followed by derivatization and headspace solid-phase microextraction (SPME) with a polydimethylsiloxane (PDMS)-coated silica fiber. Optimization of conditions including gas chromatograph injection temperature, microwave extraction power and microwave extraction time are presented. The identification and quantification (via the method of standard additions) of the extracted compounds is carried out by capillary gas chromatography with inductively coupled plasma mass spectrometric detection (GC-ICP-MS) using a unique heated interface that was designed for this work. The SPME-GC-ICP-MS method was validated for the determination of methylmercury (MeHg) concentrations in a variety of biological Standard Reference Materials (SRMs), ranging from 13.2 ng g−1 in SRM 1566b Oyster Tissue, to 397 ng g−1 in SRM 1946 Lake Superior Fish Tissue. Additionally, this method was applied to the determination of MeHg in seabird eggs (common murres, Uria aalge and thick-billed murres, Uria lomvia) collected from colonies on Little Diomede and Bogoslof islands in the Bering Sea and Saint Lazaria Island in the Gulf of Alaska and cryogenically banked in the Marine Environmental Specimen Bank. The results obtained demonstrate that SPME-GC-ICP-MS is a sensitive technique for the determination of methylmercury at trace and ultra-trace levels in a variety of natural matrices with high reproducibility and accuracy. In all instances, the sample-to-sample variability was typically 2% relative standard deviation (RSD) and the method detection limit for methylmercury was 4.2 pg g−1 (as Hg), based on a 0.5 g tissue sample of SRM 1566b Oyster Tissue.

Iodine concentration in different human brain parts.

Iodine is one of the most important essential elements as demonstrated by the fact that its deficiency can cause goitre. Nevertheless, quantitative data on its concentration in biological materials, especially in the human brain, are scarce. There is therefore a demand for accurate and reliable information on iodine in these types of samples. The purpose of the present work was to determine the concentration of total iodine in some control human brain parts by rapid radiochemical neutron activation analysis. Our second goal was to determine I distribution between lipid fraction and in brain tissue without lipid by applying two types of solvent extraction methods. The results were checked by the analysis of biological standard reference materials with certified or literature values for iodine and good agreement was found.

Speciation of Fe(III) and Fe(II) in water samples by liquid–liquid extraction combined with low-temperature electrothermal vaporization (ETV) ICP-AES

The use of 1-phenyl-3-methyl-4-benzoylpyrazolone (PMBP) as extractant for separation of Fe(III) and Fe(II) and low-temperature vaporization of the Fe(III)–PMBP chelate into ICP-AES for their speciation analysis was investigated. The factors affecting the formation of Fe(PMBP)3 chelate and its vaporization behavior were investigated in detail. PMBP was used not only as the extractant for the separation of Fe(III) and Fe(II) but also as the chemical modifier for the low-temperature ETV-ICP-AES determination of iron. Under the optimized conditions, the detection limit for iron(III) and iron(II) are both 3.2 ng/mL, with relative standard deviations of 3.9 and 4.5%, respectively. The proposed method was applied to the determination of trace iron in biological standard reference materials and the species in East Lake water samples, and the results obtained were satisfactory.

Determination of Pt, Pd and Rh in biological samples by electrothermal atomic absorption spectrometry as compared with adsorptive cathodic stripping voltammetry and total-reflection X-ray fluorescence analysis

In the present study, we evaluated a microwave digestion procedure followed by electrothermal atomic absorption spectrometry (ET-AAS) for the determination of the platinum group metals (PGM) Pt, Pd and Rh in small amounts of animal tissue. Due to the lack of certified biological standard reference materials for PGM, we performed interlaboratory comparisons using adsorptive cathodic stripping voltammetry (ACSV) after digestion of the samples by high pressure ashing (HPA) for the determination of Pt and Rh and total-reflection X-ray fluorescence (TXRF) analysis after co-precipitation of Pd with mercury for the determination of Pd, as reference methods. Suitable sample materials were obtained from laboratory experiments with mussels exposed to PGM salts or ground automobile catalytic converter material. The 3 s detection limits for microwave digestion (MWA)/ET-AAS were 270 ng g −1 (Pt), 90 ng g −1 (Pd) and 13 ng g −1 (Rh), the precision was better than 10% and the recovery was >95%. The highest divergence between the MWA/AAS and HPA/ACSV/TXRF procedures was found for Pt with values of 48 and 26%. But, even though the Pt levels exceeded the detection limit, the concentrations were near to or below the limit of determination (three times the detection limit). In contrast to Pt, the results of the different analytical procedures for Pd and Rh were comparable (<20% deviation). The combination of MWA and ET-AAS is a very rapid and relatively cheap method for routine PGM analysis in large numbers of animal tissue samples with PGM concentrations exceeding the upper ng g −1 range as occur e.g. in experimental studies or in the medical sector after treatment with Pt-anti-cancer drugs.