Signal peak detection arrangment for atomic absorption spectrometry

Claim 2

An atomic absorption spectrometer, said spectrometer providing an output information signal representative of the absorbance of a sample material under test, said information signal accompanied by repeatable, relatively short-term, substantially constant amplitude error signal components which cause a deviation of said information signal from a desired reference level, an electrical signal amplitude peak detecting means, means for applying said signal representative of the absorbance of said sample material to said peak detecting means, a signal combining circuit means, means for applying an output signal from said peak detecting means to said signal combining circuit means, a storage circuit means for storing the magnitude of an electrical signal applied thereto, means coupling said storage means to said signal combining means for combining a phase-opposed stored signal with an output signal from said peak detector, and, means for selectively coupling an output from said signal combining circuit to said storage means.

Claim 3

The atomic absorption spectrometer of claim 1 wherein said spectrometer includes means for atomizing a sample material for analysis, program control means for causing the atomization of said sample material during a predetermined portion of an operating cycle, means for coupling a control signal from said program control means to said peak detecting means for enabling the operation of said peak detector during a predetermined interval of said cycle.

Claim 4

The atomic absorption spectrometer of claim 2 wherein said program control means provides a control signal for enabling said peak detector during said atomizing interval of said cycle.

Claim 5

The atomic absorption spectrometer of claim 1 wherein said output signal of said spectrometer includes long-term error components which cause a diviation in the baseline of said absorbance representative signal from a reference level, a second signal combining circUit means having first and second input terminals and an output terminal thereof, means for applying an instrument signal to said first input terminal of said second signal combining circuit means, a second storage circuit means adapted for storing a signal level applied thereto and for providing an output signal level of opposite polarity at an output terminal thereof, means for coupling the output terminal of said second signal storage means to said second input terminal of said second signal combining means, means for coupling the output terminal of said second signal combining means to said signal peak amplitude detector, and means for selectively coupling the output terminal of said second signal combining means to the input terminal of said second storage circuit means.

Claim 6

The atomic absorption spectrometer of claim 4 wherein said peak detecting arrangement includes means for detecting the polarity of a signal applied thereto and for storing a signal in said first storage means having a polarity corresponding to the polarity of said peak detected signal.

Claim 7

The atomic absorption spectrometer of claim 4 including means for simultaneously coupling the output of said first and second signal combining means respectively to the input terminals of said first and second storage signal means.

Claim 8

The atomic absorption spectrometer of claim 6 wherein said peak detection arrangement includes first and second peak detectors, said first peak detector is arranged for sensing the peak amplitude of an input signal of a first predetermined polarity, said second peak detector is arranged for sensing the peak amplitude of an input signal of a second opposite polarity, switching means responsive to an input control signal for alternatively coupling an output signal from said first and second peak detectors to said signal combining circuit, comparator circuit means for comparing the amplitude of first and second input signals and for providing an output signal indicative of the signal of larger amplitude, means for coupling an output signal from each of said peak detectors to said comparator, and means for coupling an output signal from said comparator means to said switching means for enabling one of said switching means associated with the peak detector providing an output signal of larger amplitude and for disabling the other switching means.

Claim 9

The atomic absorption spectrometer of claim 7 wherein said first peak detector includes a plurality of cascade coupled amplifiers, polarity sensitive circuit means coupled between an output of a first amplifier and an input of a second amplifier for transmitting signals of a first predetermined polarity; and switching means coupled in parallel with said polarity sensitive circuit means for selectively by-passing said polarity sensitive circuit means, and means for controlling said switching means.