Flame photometry detection limits

Atomic absorption spectrometry is one of the most widely used techniques for the determination of metals at trace levels in solution. Its popularity as compared with that of flame emission is due to its relative freedom from interferences by inter-element effects and its relative insensitivity to variations in flame temperature. Only for the routine determination of alkali and alkaline earth metals, is flame photometry usually preferred. Over sixty elements can be determined in almost any matrix by atomic absorption. Examples include heavy metals in body fluids, polluted waters, foodstuffs, soft drinks and beer, the analysis of metallurgical and geochemical samples and the determination of many metals in soils, crude oils, petroleum products and plastics. Detection limits generally lie in the range 100-0.1 ppb (Table 8.4) but these can be improved by chemical pre-concentration procedures involving solvent extraction or ion exchange. 

The content of aluminum in the reaction solution was determined at 50 p.p.m., the content of sodium at 100 p.p.m. Up to 95% conversion, the metal content in solution did not change, but at the end of the esterification about 50% of the aluminum had separated as an insoluble substance, and only 10% of the original concentration of the alkali still existed in solution. After removing the remaining alcohol and brightening the plasticizer with adsorbents, the content of the two metals lies with 0.07 p.p.m. sodium and 0.1 aluminum at the limit of detectability. The sodium was determined by flame photometry the determination of aluminum is discussed later. 

D7. Dawson, J. B., and Tucker, B. D., Relative detection limits in emission, absorption and fluorescence flame photometry. Int. Colloq. Spectrosc., 16th, Heidelberg 2, 347-351 (1971). 

Because carbon dioxide is nonpolar, the separation of polar compounds by supercritical carbon dioxide is difficult. Thus, polar modifiers are often used for the separation of phenols and amines. Derivatization has also been employed to obtain nonpolar analytes in some applications. The UV detector has mainly been used for the detection of polar compounds. Oxidative and reductive amperometric detection was also utilized with a detection limit of 250 pg for oxidative detection of 2,6-dimethylphenol. The detection of amines has generally been achieved by FID. Other detectors used for the detection of polar analytes include Fourier transform infrared (FTIR), photodiode array, and flame photometry. 

UV—Vis = spectrophotometry FAAS = flame atomic absorption spectrometry FP = flame photometry Analytical range or detection limit given in original units. 

The separation of yttrium from the lanthanides is performed by selective oxidation, reduction, fractionated crystallization, or precipitation, ion-exchange and liquid-liquid extraction. Methods for determination include arc spectrography, flame photometry and atomic absorption spectrometry with the nitrous oxide acetylene flame. The latter method improved the detection limits of yttrium in the air, rocks and other components of the natural environment (Deuber and Heim 1991 Welz and Sperling 1999).Other analytical methods useful for sensitive monitoring of trace amounts of yttrium are X-ray emission spectroscopy, mass spectrometry and neutron activation analysis (NAA) the latter method utilizes the large thermal neutron cross-section of yttrium. For high-sensitivity analysis of yttrium, inductively coupled plasma atomic emission spectroscopy (ICP-AES) is especially recommended for solid samples, and inductively coupled plasma mass spectroscopy (ICP-MS) for liquid samples (Reiman and Caritat 1998). 

Table 7.7 Detection Limits for Flame Photometry in Commercial Instruments ...

Provided it can be excited, the HPO emission is very specific for the identification of P (Figure 14.2). Detection limits down to 0.01 mg/mL of P from the HPO line at 5262 A, and 1 mg/mL of P from the PO line at 2464 A can be reached. These limits are very variable, however, and depend not only on the matrix, but on the nature of the phosphorus compound and the excitation technique which is used. Flame photometry, using HPO emission is in widescale use for the quantitative analysis of organophosphorus pesticides and their decomposition products. 

The sensitivity of detection of some 70 elements by flame emission or absorption spectrometry can, in many instances, be very low. The level of detection of sodium by flame photometry is often limited by the residual content of the water or other solvent used for the sample e.g., 1 ng/g of sodium can be detected without difficulty. Detection limits reported for other elements range from 1 to 1000 ng/g by one or the other of these two techniques. The potential capabilities of these methods have been considerably improved by the introduction of nonflame techniques. ... 

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