Scanning Microscopy Techniques as an Assessment Tool of Materials and Interventions for the Protection of Built Cultural Heritage

Table 1

Summary of analytical techniques used in the field of built cultural heritage, regarding acquired information, sample requirements, and major limitations.

Techniques	Acquired information	Sample requirements	Limitations
Atomic absorption/emission spectroscopy; AAS/AES	(i) Elemental chemical composition; (ii) High sensibility & precision for quantitative analysis (ppm/ppb)	(i) Solid samples are converted to liquid solutions	(i) Time-consuming sample preparation; (ii) Sample destruction
Inductively coupled plasma optical emission spectrometry; ICP-OES
Fourier transform infrared spectroscopy; FTIR	(i) Molecular chemical composition; (ii) Qualitative analysis	(i) Small amount of solid & liquid samples; (ii) No sample preparation for ATR-FTIR mode; (iii) Nondestructive in situ instrumentation	(i) Peak overlay and/or shifting, when mixtures are measured; (ii) Database is required
RAMAN spectroscopy	(i) Molecular chemical composition; (ii) Qualitative analysis	(i) No preparation of solid samples; (ii) Nondestructive in situ instrumentation
X-ray fluorescence; XRF	(i) Elemental chemical composition; (ii) Quantitative analysis	(i) No preparation of solid samples; (ii) Nondestructive in situ instrumentation	(i) Quantification uncertainty; (ii) Elements of low atomic number are not detected
X-ray diffraction; XRD	(i) Mineralogical composition; (ii) Semiquantitative analysis	(i) Pulverising of solid samples; (ii) Nondestructive in situ instrumentation	(i) Detection limit above ~5%; (ii) Database is required
Particle-induced X-ray emission/particle-induced gamma-ray emission; PIXE/PIGE	(i) Elemental chemical composition	(i) No preparation of solid samples	(i) Quantification uncertainty; (ii) Elements of low atomic number are not detected
Mass spectrometry; MS	(i) Isotopic determination	(i) Pulverising of solid samples	(i) Risk of sample contamination
Gas chromatography/high-performance liquid chromatography/ionic chromatography; GC/HPLC/IC	(i) Separation techniques; (ii) GC/HPLC mainly employed in organic compounds; (iii) IC employed in inorganic compounds	(i) Samples must be solubilised	(i) Time-consuming sample preparation; (ii) Requirement of internal and external standards
Laser-induced breakdown spectroscopy; LIBS	(i) Elemental chemical composition; (ii) Qualitative & quantitative analysis	(i) No sample preparation; (ii) In situ instrumentation	(i) Surface destructive technique; (ii) Database is required
Laser-induced fluorescence; LIF	(i) Molecular chemical composition	(i) No sample preparation; (ii) In situ instrumentation	(i) Database is required; (ii) Only fluorescence compounds are detected