FLAMEFACTS NEWSLETTER

Condensed text based on a presentation made at the February 1996 meeting of the Society for Applied Spectroscopy (SAS), New England Section, Mass.,U.S.A.

by: BRUNO M. SCIFFO President of

ADVANCED TECHNICAL SERVICES GmbH

Zug, Switzerland

Introducing High Performance Flame Photometry (HPFP)Τ

..... a technological breakthrough !

Flame photometers were originally built to perform clinical tests for alkaline elements (Na, K, Li, Ca, Ba, etc). The goal of the ATS research team was to transform this instrument into an efficient general purpose analyser for science and industry that could also perform clinical tests, but was not restricted to this usage (in fact ATS has a dedicated clinical flame photometer).

Earlier flame photometers had many limitations which complicated their use. For instance, the well known response of sodium made it essential for samples to be strongly diluted and the results calculated either from a graph analytical curve, or using an electronics correction (lineariser) that was only effective in a limited measuring range.

Thus, for the analysis of Sodium samples at 5 different concentrations (31 mmol/l, 50 mmol/l, 60 mmol/l, 72 mmol/l and 100 mmol/l) a total of 10 standards, plus a blank, needed to be prepared accurately, measured and an analytical response curve established, before the analysis could be made. The dilution ratio was 1:100 and the diluent was deionized water.

For curve correction, earlier flame photometers often used 5 or 6 potentiometers, each one correcting a section of the curve. This required 5 or more standards to allow to read concentration values from the bent section of the curve. Also the instrument had to be frequently recalibrated (the zero and slope rescaled) before a complete analysis of a sample was possible.

The aim of the ATS research team was to redesign the flame photometer and obtain an instrument that is rugged, stable, simple to operate and above all gives highly precise and repeatable analysis results. Our R&D work resulted in our own proprietary technology, which we called “High Performance Flame Photometry(HPFP)Τ”. It is incorporated in the ATS 200 Series (HPFP)Τ analysers that offer among other advantages the following:

- faster measuring cycle,

- wider dynamic ranges,

- the linear straight segment of the response curve extended by a factor of 3 or better.

- minimal memory effect,

- unnecessary to use an internal standard,

- better short and long term precision,

- signal integration over a fixed time (3 or 6 seconds)

- improved detection limits,

- reduced volume of standards and analytical solutions, therefore reduced industrial waste

The linear segment and slope of the response curve is dependent on each element’s excitation potential. The benefits of an extended straight (linear) segment of an analytical curve translates into better detection limits and extended dynamic ranges (see publication ATS/1176E); the great success of ICP spectrometry is attributed to the fact that the straight segment of their linear curve extends its range by 4 to 5 orders of magnitude!

The ATS 200 (HPFP)Τ has achieved similar linearity for calcium; a linear segment of 0 to 300 ppm permits measurement ranges of 0.1 to 1.0 to 10, and 300, or 4 orders of magnitude and this using butane gas !

The ATS 200 MKI High Performance Flame Photometer (HPFP)Τ Series has new sealed optics, new electronics and a new nebulization system that enables to obtain better analytical sensitivity and precision. The analytical ranges were extended at both ends, i.e. at the lower and higher end of the analytical curve (see Fig. 3, Table 3) which eliminates the need for many dilutions of a sample. Through simplified instrument operation and a direct readout of the analysis results the time required for a full analysis cycle has been greatly reduced.

The usually slow instrument response to reach a stable reading, and the need to rinse the sample mixing chamber for a long period of time in order to return to zero, both of which are time consuming, have also been overcome. This is true also for the "memory effect", when the readings do not return to zero after the sample rinsing requiring the analyst's intervention to zero the instrument again before performing new tests. Now readings are obtained rapidly (3 or 6 seconds) and either a fixed integrated reading or continuous floating readings can be selected - the memory effect is virtually nil.

The ATS 200 MKI Series High Performance Flame Photometers (HPFP)Τ need less consumables, less dilutions, less sample preparation time and require less frequent recalibrations (table 1), and have a faster analytical cycle. One of the advantages of these optimizations in our day is the reduced industrial waste generated, saving about 70% or more of rejects that adds to environmental pollution.

With the savings in consumables and the increased analytical output the ATS 200 MKI instruments are not only very productive but are also very economic in use.

The ATS 200MKI Series High Performance Flame Photometers (HPFP)Τ will benefit laboratories in many fields of application: the environment, food & feeds, agriculture (fertilizers, soils, plants, veterinary), pharmacology, clinical, biochemistry, and countless industries.

The ATS 200MKI Series High Performance Flame Photometers (HPFP)Τ enable efficient use of a PC Data Station for which one of the pre-conditions is the performance quality of the basic instrument, as a PC system cannot correct for an unprecise instrument performance.

The ATS 200MKI Series High Performance Flame Photometer (HPFP)Τ can be supplied as a complete system which includes besides the basic instrument a dedicated sampler turntable or an intelligent autosampler and auto dilutor. Such a system greatly increases laboratory productivity and efficiency and helps meet new regulatory GLP requirements by facilitating method validation and the traceability of the chemical measurement.