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Screening programs for pediatric lead (Pb) poisoning routinely collect blood by finger stick onto specially designed filter paper (FP) for subsequent laboratory testing. Here, laser ablation inductively coupled plasma time-of-flight mass spectrometry is evaluated as a novel method for the determination of Pb in blood spotted onto FP cards. The method requires no sample pretreatment and may be particularly suitable for rapidly screening a large number of samples. Signal intensity from the ICP-MS strongly correlated (r (2) = 0.996) with Pb target values for five blood cards from a laboratory proficiency testing program. Better precision was obtained by replicate ablation line scans (<15% rsd) compared to a grid of 25 individual ablation spots (>30% rsd). Because <2% of the sample is consumed in the laser ablation analysis, selected samples can also be analyzed by traditional techniques or archived. Lead isotope ratios determined during the same total-Pb analysis appear to be effective for discerning contamination extraneous to the blood sample. Determining that an elevated result was due to contamination may negate the need for retesting with invasive pediatric venipuncture. Some elements monitored along with Pb exhibited signal profiles conducive to potential quantitation (Ca, V, Fe, Cu Zn), whereas others did not (Cr, Mn, Co, Ni, Cd, Hg, Tl, U). Copper, Ca, and V were inversely correlated with Pb (r = -0.89, -0.90, and -0.92, respectively). Scanning electron microscope images revealed surface modality differences between FP spotted with fresh whole blood and reconstituted freeze-dried blood reference material.

Additional occurrence data are needed to better understand human exposure to per- and poly-fluoroalkyl substances (PFAS) from commercially available foods in the United States. The Food and Drug Administration's (FDA) Total Diet Study (TDS) collects foods that are both nationally and regionally distributed. In 2018, 172 processed foods were collected from grocery stores around Lenexa, KS, as part of the TDS national collection. A previously developed method for the analysis of PFAS in foods as part of the TDS regional collection was modified and optimized for these samples. This method was single lab validated using 5 different matrices and method detection limits were calculated. During the analysis of these samples, challenges arose with method blanks and further investigation into statistical methods to distinguish between blank and sample concentrations were done. The confirmation of two short chain PFAS, perfluorobutanoic acid (PFBA) and perfluoropentanoic acid (PFPeA), was not possible using triple quadrupole mass spectrometry and a confirmation method was developed using high-resolution mass spectrometry. This technique was also used to investigate potential detections and interferents that fell within the retention time criteria for positive detections. In the national collection, positive detections of perfluorooctanesulfonic acid (PFOS) and perfluorononanoic acid (PFNA) were found in frozen fish sticks/patties, PFOS and perfluorodecanoic acid (PFDA) in canned tuna, and PFOS in protein powder. Concentrations were all below 150 ppt, and no other detects were confirmed above the method detection limits in any other foods., (© 2021. This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.)

Eight different analytical extraction procedures commonly used to extract mercury species from biological samples were evaluated by analyzing Tuna Fish Tissue Certified Reference Material (ERM-CE464) certified for the content of total mercury and methylmercury. Speciated isotope dilution mass spectrometry (SIDMS; US Environmental Protection Agency's method 6800) was utilized to evaluate and effectively compensate for potential errors during measurement and accurately quantify mercury species using all the extraction methods. SIDMS was used to accurately evaluate species transformations during sample pretreatment, preparation and analysis protocols. The extraction methods tested in this paper were based on alkaline extraction with KOH or tetramethylammonium hydroxide; acid leaching with HCl, HNO(3) or CH(3)COOH; extraction with L: -cysteine hydrochloride; and enzymatic digestion with protease XIV. Detection of total mercury and mercury species from all extraction methods was carried out by inductively coupled plasma mass spectrometry (ICP-MS) and high-performance liquid chromatography-ICP-MS, respectively. Microwave-assisted extraction and ultrasound-assisted extraction were found to be the most efficient alkaline digestion protocols that caused the lowest levels of transformation of mercury species (6% or less). Extraction with 5 M HCl or enzymatic digestion with protease resulted in the second-highest extraction efficiency, with relatively lower transformation of methylmercury to inorganic mercury (3 and 1.4%, respectively). Despite frequent use of acid leaching for the extraction of mercury species from tuna fish samples, the lowest extraction efficiencies and the highest mercury species transformation were obtained when microwave-assisted extraction with 4 M HNO(3) or CH(3)COOH was used. Transformations as high as 30% were found using some literature protocols; however, all the extractions tested produced accurate quantitation when corrected in accordance with the SIDMS method standardized in the US Environmental Protection Agency's method 6800. [figure: see text]

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.

Modern sanitary practices result in large volumes of human waste, as well as domestic and industrial sewage, being collected and treated at common collection points, wastewater treatment plants (WWTPs). In recognition of the growing use of sewage sludge as fertilizers and soil amendments, and the scarcity of current data regarding the chemical constituents in sewage sludge, the US National Research Council (NRC) in 2002 produced a report on sewage sludge. Among the NRC's recommendations was the need for investigating the occurrence of pharmaceuticals and personal care products (PPCPs) in sewage sludge. PPCPs are a diverse array of non-regulated contaminants that had not been studied in previous sewage sludge surveys but which are likely to be present. The focus of this paper will be to review the current analytical methodologies available for investigating whether pharmaceuticals are present in WWTP-produced sewage sludge, to summarize current regulatory practices regarding sewage sludge, and to report on the presence of pharmaceuticals in sewage sludge.

Despite the widespread use of the USEPA method (U.S. Environmental Protection Agency, 40 CFR 136 Appendix B) for the determination of method detection limit (MDL), criticisms have been raised that the method does not account for measurement bias and outliers that subsequently lead to a common misunderstanding of the requirement for the determination of MDL. This paper demonstrates that it is difficult to follow the USEPA method for verifying the MDL for analysis involving multiple metals and proposes a precision and bias criterion for determining the MDL. A multiple-point fitted profile, based on the correlation between relative standard deviation (RSD) and concentration, is used to derive a robust MDL value. Representative examples of As, Ca, Cr, and Cu are used to illustrate this procedure. A procedure for identifying outliers is also discussed.

NIST maintains a portfolio of more than 1300 standard reference materials (SRM), more than a third of these relating to measurements in the biological and environmental fields. As part of the continuous renewal and replacement efforts, a set of new marine sediments has been recently developed covering organic and inorganic determinations. This paper describes the steps taken in sample preparation, homogeneity assay, and analytical characterization and certification with specific emphasis on SRM 2702 inorganics in marine sediment. Neutron activation analysis showed the SRM to be highly homogeneous, opening the possibility for use with solid sampling techniques. The certificate provides certified mass fraction values for 25 elements, reference values for eight elements, and information values for 11 elements, covering most of the priority pollutants with small uncertainties of only several percent relative. The values were obtained by combining results from different laboratories and techniques using a Bayesian statistical model. An intercomparison carried out in field laboratories with the material before certification illustrates a high commutability of this SRM.