Flame atomic absorption , ceramics analysis

Thirty-two sherds representing five different examples of Kayenta Anasazi Pueblo II pottery (Tusayan Corrugated [TC], Medicine Black-on-Red [MB], Tusayan Black-on-Red [TB], Dogoszhi Black-on-White [DB], and Sosi Black-on-White [SB]) have been analyzed for the elements As, Ba, Co, Cr, Cm, Fe, Mn, Ni, Pb, Se, V, and Zn by using the techniques of flame atomic absorption spectroscopy (.FAA) and electrothermal atomic absorption spectroscopy (ETAA). Analytical procedures for the chemical analysis of ceramics afford accuracy and sensitivity and require only a modest capital investment for instrumentation. The sherd samples were collected at two sites, one in southern Utah (Navajo Mountain [NM]) and the second in northern Arizona (Klethla Valley [KV]). These sites are approximately 60 km apart. Statistical treatment of the data shows that only three clay types were used in the 32 sherds analyzed, and that only three elements (Fe, Pb, and Ni) are necessary to account for 100% of the dispersion observed within this sample set. 

As mentioned earlier, optical atomic spectroscopy is only able to analyze solution sample. As a result, ceramic powders to be tested should be made into solution. The solution is then broken into line droplets and vaporized into individual atoms by heating, which is the step critical to the precision and accuracy of the analysis. Flame is generally used to vaporize the solution, which is therefore also known as flame atomic absorption spectrometry or flame AA. 

Detection systems for speciation have commonly consisted of atomic spectrometry instrumentation. One of the earliest techniques employed was flame atomic absorption spectrometry (EAAS). Sample is introduced into a flame using a pneumatic nebulizer system. The light source for atomic absorption is a low pressure (a few Torr) hollow cathode lamp (HCL) that includes a ceramic cylinder cathode coated with the pure metal or a compound of the analyte. Application of 150-300 V across the electrodes produces a plasma that results in a narrow atomic emission line that is absorbed by analyte atoms in the flame. EAAS instrumentation is relatively inexpensive and easily interfaced to chromatography systems. However, HCL-EAAS is characterized by relatively poor sensitivity that has limited its use for practical speciation analysis. 

For the analysis of ceramic powders by optical atomic specfroscopy, a portion of the powder has to be converted into individual atoms. In practice, this is achieved by dissolving the powder in a liquid to form a solution, which is then broken into fine droplets and vaporized into individual atoms by heating. The precision and accuracy of optical atomic spectroscopy are critically dependent on this step. Vaporization is most commonly achieved by introducing droplets into a flame (referred to as flame atomic absorption spectrometry or flame AA). Key problems with flame AA include incomplete dissociation of the more refractory elements (e.g., B, V, Ta, and W) in the flame and difficulties in determining elements that have resonance lines in the far ultraviolet region (e.g., P, S, and the halogens). While flame AA is rapid, the instruments are rarely automated to permit simultaneous analysis of several elements. 

Traditional flame atomization methods have been preferred for atomic absorption analysis of ceramics. Very little mention has been made of electrothermal atomization (ETAA) in the literature. Although ETAA offers increased sensitivity with lower detection limits and smaller sample sizes, the problems of matrix interference (22-25) have resulted in the development of sample-specific methods for ETAA. 

CONTENTS 1. Basic Principles (J. W. Robinson). 2. Instrumental Requirements and Optimisation (J. E. Cantle). 3. Practical Techniques (J. E. Cantle). 4a. Water and Effluents (B. J. Farey and L A. Nelson). 4b. Marine Analysis by AAS (H. Haraguchi and K. Fuwa). 4c. Analysis of Airborne Particles in the Workplace and Ambient Atmospheres (T.J. Kneip and M. T. Kleinman). 4d. Application of AAS to the Analysis of Foodstuffs (M. Ihnat). 4e. Applications of AAS in Ferrous Metallurgy (K. Ohis and D. Sommer). 4f. The Analysis of Non-ferrous Metals by AAS (F.J. Bano). 4g. Atomic Absorption Methods in Applied Geochemistry (M. Thompson and S. J. Wood). 4h. Applications of AAS in the Petroleum Industry W. C. Campbell). 4i. Methods forthe Analysis of Glasses and Ceramics by Atomic Spectroscopy (W. M. Wise et al.). 4j. Clinical Applications of Flame Techniques (B.E. Walker). 4k. Elemental Analysis of Body Fluids and Tissues by Electrothermal Atomisation and AAS (H. T. Delves). 4I. Forensic Science (U. Dale). 4m. Fine, Industrial and Other Chemicals. Subject Index. (All chapters begin with an Introduction and end with References.)... 

Atomic absorption spectrometry (AAS) was established as the most popular gas chromatography (GC) detection technique for lead speciation analysis in the first years of speciation studies. The increase of the residence time of the species in the flame using a ceramic tube inside the flame and, later, the use of electrically heated tubes, made out of graphite or quartz where electrothermal atomization was achieved, provided lower detection limits but still not sufficiently low. Later, the boom of plasma detectors, mainly microwave induced plasma atomic emission (MIP-AES) and, above all, inductively coupled plasma atomic emission and mass spectrometry (ICP-AES and ICP-MS, respectively) allowed the sensitivity requirements for reliable organolead speciation analysis in environmental and biological samples (typically subfemtogram levels) to be achieved. These sensitivity requirements makes speciation analysis of organolead compounds by molecular detection techniques such as electrospray mass spectrometry (ES-MS) a very difficult task and, therefore, the number of applications in the literature is very limited. 

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