Barbara Giussani

Role of Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry in Cultural Heritage research: a review

Cultural heritage represents a bridge between the contemporary society and the past populations, and a strong collaboration between archaeologists, art historians and analysts may lead to the decryption of the information hidden in an ancient object. Quantitative elemental compositional data play a key role in solving questions concerning dating, provenance, technology, use and the relationship of ancient cultures with the environment. Nevertheless, the scientific investigation of an artifact should be carried out complying with some important constraints: above all the analyses should be as little destructive as possible and performed directly on the object to preserve its integrity. Laser ablation sampling coupled to inductively coupled plasma-mass spectrometry (LA-ICP-MS) fulfils these requirements exhibiting comparably strong analytical performance in trace element determination. This review intends to show through the applications found in the literature how valuable is the contribution of LA-ICP-MS in the investigation of ancient materials such as obsidian, glass, pottery, human remains, written heritage, metal objects and miscellaneous stone materials. The main issues related to cultural heritage investigation are introduced, followed by a brief description of the features of this technique. An overview of the exploitation of LA-ICP-MS is then presented. Finally, advantages and drawbacks of this technique are critically discussed: the fit for purpose and prospects of the use of LA-ICP-MS are presented.

Hindering biofilm formation with zosteric acid.

The antifoulant, zosteric acid, was synthesized using a non-patented process. Zosteric acid at 500 mg l−1 caused a reduction of bacterial (Escherichia coli, Bacillus cereus) and fungal (Aspergillus niger, Penicillium citrinum) coverage by 90% and 57%, respectively. Calculated models allowed its antifouling activity to be predicted at different concentrations. Zosteric acid counteracted the effects of some colonization-promoting factors. Bacterial and fungal wettability was not affected, but the agent increased bacterial motility by 40%. A capillary accumulation test showed that zosteric acid did not act as a chemoeffector for E. coli, but stimulated a chemotactic response. Along with enhanced swimming migration of E. coli in the presence of zosteric acid, staining showed an increased production of flagella. Reverse transcriptase-PCR revealed an increased transcriptional level of the fliC gene and isolation and quantification of flagellar proteins demonstrated a higher flagellin amount. Biofilm experiments confirmed that zosteric acid caused a significant decrease in biomass (−92%) and thickness (−54%).

Problems in the application of the three-step BCR sequential extraction to low amounts of sediments: an alternative validated route.

Poor recoveries are obtained if the BCR three-step sequential extraction is applied to 100 mg specimens rather than to 1 g. It is observed that analytes are lost during each phase separation which is carried out via centrifugation and can be hardly quantitatively performed on 100 mg sediment specimens. An alternative procedure, which is carried out on a single empty SPE column and involves separation by filtration, is developed to solve this problem. The proposed method is validated on 100 mg samples of certified sediment (BCR-701), but could be potentially used for even lower sediment specimens. Problems related to pH stability during step 2 and its influence on recoveries is also reported.

The effect of copper on the structure of the ammonia-oxidizing microbial community in an activated sludge wastewater treatment plant.

Molecular approaches based on both whole-cell and extracted DNA were applied to assess chronic and acute effects of copper on the ammonia oxidizing bacteria (AOB) community in an activated sludge system. The ammonia monooxygenase amoA gene was chosen as the functional marker to evaluate changes in the AOB community. Using in situ polymerase chain reaction, we were able to visualize the peripheric distribution of the amoA gene-possessing bacteria in activated sludge flocs. The AOB biomass content was constant in both chronic and acute toxicity experiments, but the ammonia oxidizing activity, measured as ammonia uptake rate, was different. The AOB community structural changes due to the copper presence were evaluated by multivariate analysis of the DGGE bands profiles. The chronic contamination caused a change in the AOB community compared to the control. In contrast, acute inputs led to a temporary change in the AOB community, after which the community was similar to the control. Recovery after acute intoxication was achieved after 72 h. The present study reports on the effects of chronic and acute copper contamination on the ammonia uptake ability of the AO microorganisms and the structure of the AOB community in a wastewater system and, as a consequence, gives indications on the response of wastewater plants under similar conditions.

Water and snow chemistry of main ions and trace elements in the karst system of Monte Pelmo massif (Dolomites, Eastern Alps, Italy)

Water and snow chemistry of a high-altitude karst environment, the Monte Pelmo massif in the Dolomites (Eastern Alps, Italy), was investigated by a multidisciplinary analytical approach using ‘clean’ trace-metal techniques. Main ions of environmental significance (F–, HCOO–, Cl–, NO2–, NO3–, SO42–, Na+, NH4+, K+, Ca2+, Mg2+, HCO3–) were analysed by high-performance ion chromatography (IC). Trace elements of natural (Li, B, Mn, Co, Cu, U) as well as anthropic (Cr, Ni, Zn, Pb) origin were investigated by inductively coupled plasma-mass spectrometry (ICP-MS). Analytical data on filtered samples indicated that snow chemistry is dominated by the dissolution of air-borne particulate matter, primarily red dust of Saharan origin, which appears to be a preferred vehicle of contaminant transportation. In water samples, dolomite weathering was the predominant chemical step in the presence of sulfate ions, leading to excess magnesium concentrations and to Mg:Ca ratios often exceeding unity. The combined use of ICP-MS for trace element determination and chemometric tools, such as principal component analysis (PCA) and cluster analysis (CA), provided evidence of the absence of local anthropic pollution sources, and the presence of divalent transition metal cations associated with gypsum deposits. Finally, the excess uranium content was found to be associated with karst waters, and it could possibly have been a ‘natural’ tracer to characterise deep circulations.

Sub-lethal concentrations of Muscari comosum bulb extract suppress adhesion and induce detachment of sessile yeast cells

The formation of yeast biofilm on food industry equipment can lead to serious hygiene problems and economic losses due to food spoilage and equipment impairment. This study explored the ability of a sub-lethal concentration of the bulb extract of Muscari comosum to modulate adhesion of Candida albicans and subsequent biofilm development by this fungus. The HPLC profile of the ethanolic bulb extract showed phenolic constituents, which were found to undergo Folin-Ciocalteu reagent reduction. Prior to the adhesion tests, it was shown that up to 4000 mg l−1 of natural extract did not adversely affect fungal growth nor did it act as a carbon energy source for C. albicans. Mathematical models predicted that 4000 mg l−1 and 700 mg l−1 of bulb extract would cause more than 98% reduction in fungal coverage on abiotic surfaces, without killing the planktonic cells. When added to C. albicans biofilm, the natural extract was shown to induce the dispersion of sessile cells in a dose-dependent manner.

Interpreting complex trace element profiles in sediment cores from a multi-basin deep lake: the western branch of Lake Como

The concentration profiles of Co, Ni, Cu, Zn, Sc, Y, As, Cd, Pb, U and the rare earth elements (REE) were determined by inductively coupled plasma–mass spectrometry (ICP-MS) in three sediment cores sampled in the western branch of Lake Como (northern Italy). This hydrographically closed branch has a complex morphology, with a maximum depth of 425 m and an approximate length of 30 km and it is affected to different extents by direct discharges and atmospheric depositions. The present study is the first attempt to deeply investigate trace element profiles in the sediments of this lake. The concentration trends of cores sampled in different zones were compared and the different patterns were interpreted on the basis of local runoff and/or global atmospheric sources. The concentrations of Cr, Zn, Pb, Cd and Cu, which are representative proxies of anthropogenic activities, were found to increase moving toward the tip of the branch, where human activities are concentrated. A distinction between atmospheric, runoff and crustal contribution to element levels in the sediment cores was proposed based on both profile analysis and principal component analysis (PCA).

A viscous film sample chamber for Laser Ablation Inductively Coupled Plasma – Mass Spectrometry

Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry (LA-ICP-MS) is a powerful method to determine the elemental composition of solid-state samples as it combines the high sensitivity and isotope selectivity of ICP-MS detection and the simplicity of laser ablation sampling. This technique enables rapid multiple sampling of the analysed material, such as needed for mapping or in-depth profiling applications. However, the duration of these measurements is practically restricted by the time taken for the particle to be transported from the sampling point to the ICP torch. The ablation cell, i.e. the sample holder, should combine high removal rate, high efficiency (i.e. complete transport of the ablated material) and reduced memory effects. These goals may be achieved by carefully designing the geometry of the cell and its gas flow patterns. A new cell design which enables a homogeneous wahout time of around 210 ms from a cylindrical chamber with 70 mm diameter is introduced in this paper. Washout time was determined as the time for the transient signal of 238U from a NIST610 glass standard to fall to 10% of its peak value. This result is achieved by combining a diffused, cylindrical flow pattern with an extraction tube coaxial with the laser beam and fixed to the laser assembly which enables the sampling point to be constantly positioned on the ablation spot. The lower part of the cell is mounted on the x,y stage for sample movement: the cell sealing is warranted by a viscous film junction between the lower and upper cell parts. Optimisation and performances of the apparatus are discussed in detail and performances are compared to existing designs.