On-line gradient calibration for atomic absorption spectrometry

Abstract

A microprocessor-controlled, automated, on-line method for generating calibration standards is described. Mathematical gradients, programmed with a high-performance liquid chromatographic pump module, mix stock and diluent solutions to form desired concentrations. On-line produced gradient calibrations are demonstrated to be comparable to those made with individual solution standards. Advantages of the technique are the convenience and savings involved in maintaining a limited selection of stock solutions and the ease of performing standard additions calibrations. A possible drawback is a slight, but noticeable, time lag between successive gradient steps.

Automatic Preparation of Calibrating Solutions for Quantitative Analysis by ICP-MS

“…The minimum control volume was comparable to that obtained with the plunger pumps used in Ref. 12. The correlation coefficient obtained in the present work was sufficient for instrumental analysis and comparable to those obtained in Refs.…”

“…[6][7][8][9][10][11] There are multiple reports about the on-line generation of gradient calibrating solutions as well as for on-line standard addition samples used for atomic spectrometry. [12][13][14][15][16] However, such on-line processes may not accomplish the requirements for analyses following industrial standards from the viewpoint of the re-measurement of an identical solution for quality control of the analytical results. There are also commercially available instruments for offline sample dilution.…”

“…As can be seen from Fig. 1, there are 12 basic parts in the present automatic system: a pressure regulator (1), a needle valve (2), a solution box (3), three solution bottles (4 to 6), three electro-magnetic valves (7 to 9), a flow sensor (10), a bottle for calibrating solution (11), and a controlling device (12). The controlling device includes an I/O board and a computer.…”

“…As can be seen from Table 3, a flow meter or a flow sensor was used in Ref. 12,Ref. 16, and the present work, which helped to ensure that the concentration in obtained solution would be traceable to that in the initial solution.…”

Automatable on-line generation of calibration curves and standard additions in solution-cathode glow discharge optical emission spectrometry

“…1 (a) The standard-addition results here are superior to those in earlier experiments with gradient standard addition in ICP-OES [28], where errors as large as 11% were reported. Given that the Hitachi L-7100 pump used in the present study has similar specifications to the Beckman Gold Model 126 pump used in the earlier work [27,28], any difference in the gradient pumps seems unlikely to be the cause of the improved accuracy. One possible basis for the disparity is the concentration at which at which the samples were analyzed.…”