Application of micro-dried droplets for quantitative analysis of particulate inorganic samples with LA-ICP-MS demonstrated on surface-modified nanoparticle TiO2 catalyst materials.

A quick, flexible and reliable method was developed, based on laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), for accurate assessment of nanomaterial composition with sample amounts in the picogram to nanogram range. We demonstrate its capabilities for the analysis of surface-modified TiO2 nanoparticulate (NP) catalyst materials. For sampling, suspensions of NP were deposited on a substrate material, ablated with a pulsed laser and then analysed using quadrupole ICP-MS. The calibration and quantification approach is based on the use of so-called micro-dried droplets (µDD) as the standard material. To overcome some of the major drawbacks of conventional dried droplet approaches, self-aliquoting wells were used in this work. By mimicking the ablation conditions for the sample and standard, it was possible to create a pseudo-matrix-matched calibration, not only for this specific NP composition but also for a larger variety of samples. A commercially available reference material (AUROlite™, Strem Chemicals) was used to compare the method against established methods such as slurry analysis and microwave-assisted digestion in combination with subsequent liquid sample measurement. The results obtained with the proposed procedure (0.74%wt ± 0.13%wt) are in good agreement to a certified value (0.8%wt) and added an additional layer of information. Due to the significantly reduced sampling size in comparison with the investigated liquid measurement approaches, it was possible to obtain information about the homogeneity of the catalyst material. The results indicate that the AUROlite™ reference material has a heterogeneous loading which requires more than 300 pg of material to be used to cancel out. This was not observed for the custom materials discussed in this work. Graphical abstract.

Nanoparticles in medicine: Current challenges facing inorganic nanoparticle toxicity assessments and standardizations.

Although nanoparticles research is ongoing since more than 30years, the development of methods and standard protocols required for their safety and efficacy testing for human use is still in development. The review covers questions on toxicity, safety, risk and legal issues over the lifecycle of inorganic nanoparticles for medical applications. The following topics were covered: (i) In vitro tests may give only a very first indication of possible toxicity as in the actual methods interactions at systemic level are mainly neglected; (ii) the science-driven and the regulation-driven approaches do not really fit for decisive strategies whether or not a nanoparticle should be further developed and may receive a kind of "safety label". (iii) Cost and time of development are the limiting factors for the drug pipeline. Knowing which property of a nanoparticle makes it toxic it may be feasible to re-engineer the particle for higher safety (safety by design). FROM THE CLINICAL EDITOR: Testing the safety and efficacy of nanoparticles for human use is still in need of standardization. In this concise review, the author described and discussed the current unresolved issues over the application of inorganic nanoparticles for medical applications.

A multicenter nationwide reference intervals study for common biochemical analytes in Turkey using Abbott analyzers.

BACKGROUND: A nationwide multicenter study was organized to establish reference intervals (RIs) in the Turkish population for 25 commonly tested biochemical analytes and to explore sources of variation in reference values, including regionality. METHODS: Blood samples were collected nationwide in 28 laboratories from the seven regions (≥400 samples/region, 3066 in all). The sera were collectively analyzed in Uludag University in Bursa using Abbott reagents and analyzer. Reference materials were used for standardization of test results. After secondary exclusion using the latent abnormal values exclusion method, RIs were derived by a parametric method employing the modified Box-Cox formula and compared with the RIs by the non-parametric method. Three-level nested ANOVA was used to evaluate variations among sexes, ages and regions. Associations between test results and age, body mass index (BMI) and region were determined by multiple regression analysis (MRA). RESULTS: By ANOVA, differences of reference values among seven regions were significant in none of the 25 analytes. Significant sex-related and age-related differences were observed for 10 and seven analytes, respectively. MRA revealed BMI-related changes in results for uric acid, glucose, triglycerides, high-density lipoprotein (HDL)-cholesterol, alanine aminotransferase, and γ-glutamyltransferase. Their RIs were thus derived by applying stricter criteria excluding individuals with BMI >28 kg/m2. Ranges of RIs by non-parametric method were wider than those by parametric method especially for those analytes affected by BMI. CONCLUSIONS: With the lack of regional differences and the well-standardized status of test results, the RIs derived from this nationwide study can be used for the entire Turkish population.

Setting action levels for drinking water: are we protecting our health or our economy (or our backs!)?

Clean and healthy drinking water is important for life. Drinking water can be drawn from streams, lakes and rivers, directly collected (and stored) from rain, acquired by desalination of ocean water and melting of ice or it can be extracted from groundwater resources. Groundwater may reach the earth's surface in the form of springs or can be extracted via dug or drilled wells; it also contributes significantly to river baseflow. Different water quality issues have to be faced when utilising these different water resources. Some of these are at present largely neglected in water quality regulations. This paper focuses on the inorganic chemical quality of natural groundwater. Possible health effects, the problems of setting meaningful action levels or maximum admissible concentrations (MAC-values) for drinking water, and potential shortcomings in current legislation are discussed. An approach to setting action levels based on transparency, toxicological risk assessment, completeness, and identifiable responsibility is suggested.

A procedure for decreasing uncertainty in the identification of chemical compounds based on their literature citation and cocitation. Two case studies.

An identification procedure connected with selection of candidates for identification according to high values of their literature citation and cocitation is suggested. The citation rate of the compound is the number of different literature units, such as papers, patents, etc., recording its name. The cocitation rate is the number of such units mutually recording the names of two corresponding compounds or the compound and the sample/matrix. General citation of a chemical compound is assumed to be related to the prior probability of its being contained in a sample to be analyzed. This citation measures abundance and popularity of the compound. Cocitation of a compound with a known/identified constituent of a sample is related to their mutual similarity in structure or properties, origin, use, etc. This data processing method is validated by counting citations and cocitations for detected impurities in pure n-hexane and naphthalene, polycyclic aromatic hydrocarbons in waste gas, as compared with counts for similar or dissimilar compounds that are absent in the samples. The analytes are preidentified by combined gas chromatography and mass spectrometry techniques. A median and a mean value of citation and cocitation are always higher for the group of unambiguously identified compounds. A difference between identified and similar compounds in citations or cocitations may be rather insignificant, with combined evaluation of both indicators distinguishing these groups. Chemical dissimilarity results in a large difference in cocitation values.