Lanthanum nitrate demonstrated no genotoxicity in the conducted tests.

Given the widespread applications in industrial and agricultural production, the health effects of rare earth elements (REEs) have garnered public attention, and the genotoxicity of REEs remains unclear. In this study, we evaluated the genetic effects of lanthanum nitrate, a typical representative of REEs, with guideline-compliant in vivo and in vitro methods. Genotoxicity assays, including the Ames test, comet assay, mice bone marrow erythrocyte micronucleus test, spermatogonial chromosomal aberration test, and sperm malformation assay were conducted to assess mutagenicity, chromosomal damage, DNA damage, and sperm malformation. In the Ames test, no statistically significant increase in bacterial reverse mutation frequencies was found as compared with the negative control. Mice exposed to lanthanum nitrate did not exhibit a statistically significant increase in bone marrow erythrocyte micronucleus frequencies, spermatogonial chromosomal aberration frequencies, or sperm malformation frequencies compared to the negative control (P > 0.05). Additionally, after a 24-h treatment with lanthanum nitrate at concentrations of 1.25, 5, and 20 µg/ml, no cytotoxicity was observed in CHL cells. Furthermore, the comet assay results indicate no significant DNA damage was observed even after exposure to high doses of lanthanum nitrate (20 µg/ml). In conclusion, our findings suggest that lanthanum nitrate does not exhibit genotoxicity.

Combined in vitro tests as an alternative to in vivo eye irritation tests.

Accurate methods that test the eye irritation potential of chemicals, which do not involve the use of animals, are needed to meet new regulatory standards. We evaluated the applicability and predictive capacity of five in vitro tests for eye irritation: the Hen's Egg Test-Chorioallantoic Membrane (HET-CAM) assay; the Chorioallantoic Membrane-Trypan Blue Staining (CAM-TBS) assay; the Fluorescein Leakage Test (FLT); the 3T3-Neutral Red Uptake (3T3-NRU) cytotoxicity assay; and the red blood cell (RBC) haemolysis assay. A panel of 16 chemicals (some at multiple concentrations) was assessed by using the five tests, and the results were compared with historical in vivo Draize test data. The results showed rank correlation and class concordance between the five alternative methods and the Draize test for the 16 chemicals. These in vitro assays had good predictive capacity, reproducibility and reliability when compared to the Draize test. The best relationship was between the HET-CAM, CAM-TBS and FLT results, and the modified maximum average score(s) (MMAS). A prediction model (PM) was developed, based on the maximum possible correlation between the MMAS and the HET-CAM, CAM-TBS and FLT results. The PM had a good predictive capacity when compared to the results of animal tests, indicating its potential value for the in vitro screening of chemicals for eye irritation effects.

Spectrophotometric determination of silver with 2-(2-quinolylazo)-5-diethylaminoaniline.

A new chromogenic reagent, 2-(2-quinolylazo)-5-diethylaminoaniline (QADEAA) was synthesized. A highly sensitive, selective and rapid method for the determination of silver based on the rapid reaction of silver (I) with QADEAA has been developed. In the presence of sodium citrate-sodium hydroxide buffer solution (pH 6.5) and sodium dodecyl sulfonate (SDS) medium, QADEAA reacts with silver to form a violet complex of molar ratio 1:2 (silver to QADEAA). The molar absorptivity of the complex is 1.39x10(5) l mol(-1) cm(-1) at 580 nm. Beer's law is obeyed in the range of 0.01-0.6 mug ml(-1). The relative standard deviation for 11 replicate samples of 0.2 mug ml(-1) is 1.67%. This method can be applied to the determination of silver in water with satisfactory results.