Standard dilution analysis (SDA) is a novel calibration method that may be applied to most instrumental techniques that will accept liquid samples and are capable of monitoring two wavelengths simultaneously. It combines the traditional methods of standard additions and internal standards. Therefore, it simultaneously corrects for matrix effects and for fluctuations due to changes in sample size, orientation, or instrumental parameters. SDA requires only 200 s per sample with inductively coupled plasma optical emission spectrometry (ICP OES). Neither the preparation of a series of standard solutions nor the construction of a universal calibration graph is required. The analysis is performed by combining two solutions in a single container: the first containing 50% sample and 50% standard mixture; the second containing 50% sample and 50% solvent. Data are collected in real time as the first solution is diluted by the second one. The results are used to prepare a plot of the analyte-to-internal standard signal ratio on the y-axis versus the inverse of the internal standard concentration on the x-axis. The analyte concentration in the sample is determined from the ratio of the slope and intercept of that plot. The method has been applied to the determination of FD&C dye Blue No. 1 in mouthwash by molecular absorption spectrometry and to the determination of eight metals in mouthwash, wine, cola, nitric acid, and water by ICP OES. Both the accuracy and precision for SDA are better than those observed for the external calibration, standard additions, and internal standard methods using ICP OES.

The fourteen Lanthanides are determined by tungsten coil atomic emission spectrometry. Twentyfive microlitre sample aliquots are placed directly on the coil. A simple constant current power source carefully dries the sample prior to analysis. During this dry step, the voltage is monitored to prevent over heating. This allows for shorter atomization programs, while improving sensitivity and coil lifetime. During the 5 s high temperature atomization step, the emission signals for as many as seven Lanthanides are determined simultaneously in the same 55 nm spectral window. The analytical figures of merit for all 14 natural Lanthanides are reported and compared with nitrous oxide flame atomic emission spectrometry. Tungsten coil atomic emission concentration detection limits are in the range 0.8 (Yb) to 600 (Pr) mg l À1 , and are lower than those for the flame in most cases. The absolute detection limits are near or below the ng level: significantly lower than the flame detection limits due to the smaller sample volume required. A three-fold improvement in detection limit may be realized by combining the signals for multiple emission lines for a single element. The method is applied to the determination of seven Lanthanides in a soil sample acquired from the National Institute of Standards and Technology. After a simple acid extraction, the measured values agree with the reported values with 95% confidence in all cases but one, Yb. Finally, a conditioning program for new tungsten coils enhances reproducibility and maximizes the emission signal.

No abstract

No abstract

No abstract

Automated standard dilution analysis provides rapid, accurate, and precise calibrations, correcting for both matrix effects and source fluctuations.

No abstract

A new double atomizer arrangement for tungsten coil atomic emission spectrometry is described. Two small constant current power supplies, a Czerny-Turner spectrograph, and a charge coupled device (CCD) detector are used to determine refractory elements in water samples. The analytical figures of merit for Ba, Sr, Ti, and V are reported and compared with the single coil arrangement. The use of two atomizers provides more energy for the atomization and excitation of the analytes and consequently improves sensitivity. Addition of a second coil improves limits of detection for refractory elements by a factor of 40 (V) and 5 (Ti). Using 25 ml sample volumes, the limit of detection for V is 10 mg l À1 at the 437.9 nm emission line, and 400 mg l À1 for the 399.9 nm Ti emission line. Vanadium is determined in a polluted water certified reference material, and the results agree with the certified value (250 mg l À1 ) at the 95% confidence level. For Ba and Sr, which emit strongly with a single coil, the double coil detection limits are improved by less than a factor of two: 0.007 mg l À1 Ba and 0.4 mg l À1 Sr. Emission signals for Ag, Cu and Sn are observed for the fist time with a tungsten coil atomic emission spectrometry (WCAES) system. A new method to determine the gas phase temperature by atomic emission spectrometry is also presented. Emission intensities for Dy (418.7 and 421.1 nm) and Eu (462.7 and 466.2 nm) are used to calculate Boltzmann temperatures for both the single and double coil arrangements. Temperature values calculated by this method agree with the traditional optical two-line absorption method using Sn (284.0 and 286.3 nm).