Langmyhr (1967) reported that double evaporation with HClO 4 at 180 ☌ gives about the same trace residue of fluoride as one evaporation with H 2SO 4 at 250 ☌. The order of effectiveness in removing residual amounts of fluorine decreases in the order of sulfuric acid, perchloric acid, and nitric acid. For example, the high boiling point of HClO 4 (203 ☌) compared with that of HF (112 ☌) ensures the complete removal of fluorides and the more efficient attack of refractory minerals due to the increased boiling temperature of the reaction mixture and the high solubility of perchlorates ( Potts and Robinson, 2003 Totland et al., 1992). Evaporation using a mineral acid in addition to hydrofluoric acid also facilitates the removal of fluorine ions and ensures that insoluble fluorides are converted to more soluble salts. Silicon is quantitatively removed as the volatile silicon tetrafluoride SiF 4, which reduces the total amount of dissolved solid in the solutions and makes the solution far more stable because Si in the solution tends to hydrolyze and precipitate to form undissolved polysilicic acid. Therefore, open vessel acid digestion has not been considered to be a state-of-the-art technology in trace and ultratrace sample preparation ( Matusiewicz, 2003).įor the digestion of geologic samples, HF in combination with other mineral acids (most commonly nitric and perchloric acids) in an open vessel is routinely used ( Chao and Sanzolone, 1992 Jarvis, 1990, 1992 Jenner et al., 1990 Johnson and Maxwell, 1981 Potts, 1987 Potts and Robinson, 2003 Robinson et al., 1999 Šulcek and Povondra, 1989).

Other disadvantages of open vessel digestions are the potential risk of contamination from the laboratory air and the large amounts of reagents that are required and the potential loss of trace elements. However, the maximum digestion temperatures are limited by the ambient-pressure boiling point of the corresponding acid or acid mixture. This method is an extremely important value for routine analysis because of its flexibility in the control of digestion parameters, such as temperature, time, and the addition of reagents.

It refers to acid attack in open containers or screw-top vials (low pressure) placed on a hot plate. Open vessel acid digestions have long been a popular and simple method for the digestion of inorganic and organic sample materials in chemical laboratories. Qi, in Treatise on Geochemistry (Second Edition), 2014 15.5.3.1 Open Vessel Acid Digestions The elemental analysis of paper and gel inks was studied using the micro-spectrochemical analysis techniques of LA-ICP-MS and LIBS 112 and the elemental composition of blue ballpoint pen ink was determined by LA-ICP-MS 113 as was the use of TXRF for the elemental characterization of ink samples. The novel application of micro-attenuated total reflectance sampling coupled to FTIR was also reported for the study of documents containing red seal inks, 110 and the use of ToF-SIMS for the simultaneous analysis of organic and inorganic components from ballpoint pen inks 111 was also reported. 107 The Raman and SERS analysis of synthetic dyes found in ballpoint pen inks 108 and LDI-MS analysis of pigmented inkjet printer inks and printed documents 109 were also recently reported. The characterization of naturally and artificially aged inks and papers was conducted using pyrolysis-GC-MS. 104 ESI-MS of both dyes and the vehicles in extracted ink from a document was reported 105 as was the use of LDI-MS 106 for the sampling and characterization of inks. 102 The organic dye analytes in inks were sampled and analyzed with the use of a variety of techniques including laser desorption ionization MS 103 and direct analysis in real time (DART) MS. 101 Direct solid sampling of printer toners for chemical characterization was reported using LA-ICP-ToF-MS.

A comparison of different methods (XRF, LA-ICP-MS, and IRMS) for the analysis of paper was also recently reported. Almirall, in Comprehensive Sampling and Sample Preparation, 2012 1.23.7.2 Ink and Paper AnalysisĪcid digestion followed by ICP-MS 100 procedures were reported for the elemental analysis of paper within the field of document examination in order to discriminate between and associate paper sources.

Digested organics brew