Paint sample analysis

Because of the risk of lead poisoning, the exposure of children to lead-based paint is a significant public health concern. The first step in the quantitative analysis of lead in dried paint chips is to dissolve the sample. Corl evaluated several dissolution techniques. " In this study, samples of paint were collected and pulverized with a Pyrex mortar and pestle. Replicate portions of the powdered paint were then taken for analysis. Results for an unknown paint sample and for a standard reference material, in which dissolution was accomplished by a 4-6-h digestion with HNO3 on a hot plate, are shown in the following table. 

As indicated in Section 6.2.2, DI-CIMS suffers from poor reproducibility. For nonvolatile additives that do not evaporate up to 350 °C, direct quantitative analysis by thermal desorption is not possible. The method depends on polymer formulation standards that are reliably mixed. Wilcken and Geissler [264] described rapid quality control of l- xg paint samples by means of temperature-programmable DI-EIMS with PCA evaluation. 

As microwave sample preparation has evolved, standard microwave procedures have been developed and approved by numerous standard methods organisations (ASTM, AOAC International, EPA, etc.), see ref. [64]. Examples are standard test methods for carbon black/ash content (ASTM Method D 1506-97), lead analysis in direct paint samples (ASTM Method E 1645-94), etc. Table 8.15 shows some microwave ashing references (detection weight). A French AFNOR method utilises the atmospheric pressure single-mode microwave method as an alternative sample preparation procedure for Kjeldahl nitrogen determination [84], The performance of a microwave-assisted decomposition for rapid determination of glass fibre content in plastics for QC has been described [85]. 

ASTM. 1998c. ASTM E 1645. Standard practice for the preparation of dried paint samples for subsequent lead analysis by atomic spectrometry. American Society for Testing and Materials. 

A 68 element ICP-MS scan was performed on one dried white-colored paint sample. The chemical elements scanned for during the ICP analysis and the detection limits are provided in Table 5. Approximately 0.5 g of each sample was prepared by an acid digestion technique prior to conducting the ICP-MS analysis. Shown in Table 6 are the quantified ICP-MS results for the sample. Elements scanned for but not detected are either not present in the sample or may be present below the detection limit. 

In conclusion, the paint sample was comprised of 63.3 wt% solids (polymers and fillers) and 36.7 wt% solvent. The solids were likely comprised of calcium carbonate and titanium dioxide at 12.6 and 17.7 wt%, respectively, of the total sample including solvent. The calcium carbonate and titanium dioxide were calculated based on the measured levels of calcium and titanium from the ICP analysis. Not counting the calcium and titanium levels there is 4.9 wt% of additional metals present. Based on the calcium carbonate level and titanium dioxide level along with the remaining percentage of metals present, 34.9 wt% of the total sample is accounted for. Therefore, the maximum level of alkyd in the sample is 28.4 wt%. TGA is recommended in order to quantify the level of alkyd and total level of mineral fillers in the dried paint sample. 

In the analysis of paint samples, a stepwise extraction of the various lipid and resinous components has been proposed [33] which uses isooctane, methanol, chloroform/methanol (7 3) and methanol/oxalic acid (10%). The last extraction releases FAs from the metal soaps. 

The analysis of paint samples represents a peculiar case, in which the identification of lipids is made virtually possible by the fact that the range of used materials is limited to drying oils (linseed, poppy seed, walnut, tung), egg yolk, and beeswax. Safflower oil (from... 

Table 9.2 Derivatisation methods for the GC analysis of protein hydrolysates from paint samples...

Consider the analysis of paint for lead content. The lead is the analyte the paint is the matrix and the process of analysing the paint sample for lead is the test. 

There is now available laser ablation ICP-MS which allows solid samples to be analysed directly. It is an important techniqne for nse in the forensic analysis of vehicle paint samples at the scene of hit-and-rnn crimes . 

It can be seen that for factory A, two out of eleven batches differ from the others, whereas for factory B three groups of paints can be discriminated three batches are characterized by the ratios of peak heights of the characteristic substance of 0.5 0.1, two batches 0.7 0.1 and six batches 0.8 0.1. Similar results could not be obtained by inorganic analysis [16]. Emission spectroscopic analysis, for example, identified 53 paint samples out of 190, as opposed to 141 identified by Py—GC [16]. 

Other techniques are used to identify pigments based on their molecular fragments. These techniques include UV-visible reflectance spectroscopy, infrared (IR) spectroscopy, mass spectrometry, and X-ray diffraction (XRD). Some thermal methods exploit differences in physical characteristics that are sensitive to the bulk properties of a paint sample. Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) are often used. Finally, separation techniques such as liquid chromatography (LC) have been used to identify a wide range of dyes. 

Diamond anvil cells (low-pressme or high-pressure) have long been used in the successful measurement of transmission spectra of small paint samples these latter are squeezed with light pressure between two type II diamonds into a transparent film to obtain an appropriate thickness. For transmittance analysis, potassium bromide, KBr (or cesium iodide, Csl) micropellet constitutes a simple solution. 

For quantitative X-ray analysis, electron probe microanalyzers (EPMA, EPA, or EMMA) are able to determine the elemental concentration by X-ray emission from the microvolume of paint samples where a static electron beam interacts. However, due to inhomogeneity of paint samples nonquantitative... 

Chromatographic methods Gas chromatography (GC) is the most useful technique for quantitative analysis of solvent mixtures in paint samples. The solvent, after isolation from the other components of the paint, is injected directly into the chromatograph. 

Fleadspace GC permits direct analysis of paint samples without prior separation, providing a rapid... 

X-ray fluorescence (XRF) spectroscopy is useful for qualitative elemental analysis of paint samples. It does not require dissolution of the sample and can be applied to dry films. When an energy-dispersive instrument is employed, XRF provides rapid information on the presence of elements of atomic number higher than or equal to 12 (e.g., above magnesium). However, from a quantitative point of view, the sensitivity, accuracy, and reproducibility of XRF measurements is lower than that of flame, electrothermal, or plasma atomic spectrometry. 

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