High speed cross-correlation frequency domain fluorometry-phosphorimetry

• US 5,212,386 A
• Filed: 12/13/1991
• Issued: 05/18/1993
• Est. Priority Date: 12/13/1991
• Status: Expired due to Term

• Current Assignee: ISS
• Original Assignee: ISS
• Inventors: Gratton, Enrico, Barbieri, Beniamino
• Primary Examiner(s): FIELDS, CAROLYN
• Application Number:
  US07/807,261
• Time in Patent Office: 522 Days
• Field of Search: 250/458.1, 250/459.1, 250/461.1, 250/461.2, 356/317, 356/318, 356/417
• US Class Current: 250/458.1
• CPC Class Codes: G01N 21/6408 with measurement of decay time, time resolved fluorescence

Abstract

Apparatus for cross-correlation frequency domain fluorometry and/or phosphorimetry in which means are provided for sequentially performing runs of the cross correlation frequency domain fluorometry and/or phosphorimetry at sequentially differing first and second frequencies. The intensities of signal responses of the runs are detected at the respective cross-correlation frequency in each run. The detection of the signal response is prolonged in each run until an integrated signal with a specified standard deviation has been acquired at each of the differing runs. Preferably the sequential runs are automatically executed by a program. Also, the waveforms sensed by deriving the resultant signal response in each run are folded. That is: corresponding segments of the waveforms are superimposed to obtain an average waveform value for each run having an increased signal to noise ratio over the individual waveform segments. Also, preferably, a software-created variable frequency digital filter is used to filter signal responses at the cross-correlation frequency.

Claims

1. In apparatus for cross-correlation frequency domain fluorometry-phosphorimetry, which comprises:

a source of electromagnetic radiation;

means for amplitude modulating the electromagnetic radiation at a first frequency;

means for directing the amplitude-modulated electromagnetic radiation at a sample;

means for detecting the luminescence of the sample;

means for providing a signal coherent with amplitude modulated signals produced by said amplitude modulating means, at a second frequency, to said detecting means;

means for modulating the gain of said detecting means, or multiplying the output of said detecting means, by said signal;

said second frequency being different from said first frequency; and

means for deriving a resultant signal from said electromagnetic radiation and said detecting means at a frequency of the difference between said first and second frequencies, to detect phase shift and modulation changes of said luminescence from that of said electromagnetic radiation;

the improvement comprising, in combination;

means for sequentially performing runs of said cross-correlation frequency domain fluorometry-phosphorimetry at sequentially differing first and second frequencies;

means for detecting the intensities of signal responses of said runs at the respective cross-correlation frequency which is the difference of the respective first and second frequencies used in each run; and

means for prolonging the detecting of each signal response at each of said differing first and second frequencies, until an integrated signal with a specified standard deviation has been acquired at each of said differing first and second frequencies.

2. The apparatus of claim 1 in which means are provided for automatically executing a program of sequentially performed runs.

3. The apparatus of claim 1 in which means are provided for synchronizing the acquisition of data waveforms sensed by said resultant signal deriving means in each run with the phase of the signal modulating the electromagnetic radiation at said first frequency, and for superimposing corresponding segments of said waveforms thus sensed to obtain an average waveform value for each run having an increased signal to noise ratio over the individual waveform segments.

4. The apparatus of claim 1 in which said resultant signal deriving means comprises variable frequency digital filter means.

5. The apparatus of claim 4 in which said digital filter means is set to filter signal responses at substantially the frequency which is the difference of the respective first and second frequencies used.

6. The apparatus of claim 5 in which said digital filter means is capable of filtering with a bandwidth narrowing over time as a signal response is detected.

7. The apparatus of claim 6 in which the signal from said resultant signal deriving means is automatically amplified by automatic gain means without phase and modulation changes.

8. The apparatus of claim 1 in which the first and second frequencies are each generated by frequency synthesizer means, the frequency of the difference between said first and second frequencies being essentially 50 to 1000 hertz.

9. In apparatus for cross-correlation frequency domain fluorometry-phosphorimetry, which comprises:

a source of electromagnetic radiation;

means for amplitude modulating the electromagnetic radiation at a first frequency;

means for directing the amplitude-modulated electromagnetic radiation at a sample;

means for detecting the luminescence of the sample;

means for providing a signal coherent with amplitude modulated signals produced by said amplitude modulating means, at a second frequency, to said detecting means;

means for modulating the gain of said detecting means or multiplying the output of said detecting means by said signal;

said second frequency being different from said first frequency; and

means for deriving a resultant signal from said electromagnetic radiation and said detecting means at a frequency of the difference between said first and second frequencies, to detect phase shift and modulation changes of said luminescence from that of said electromagnetic radiation;

the improvement comprising, in combination;

means for automatically and sequentially performing runs of said cross-correlation frequency domain fluorometry-phosphorimetry at sequentially differing first and second frequencies;

means for detecting the intensities of signal responses of said runs at the respective cross-correlation frequency which is the difference of the respective first and second frequencies used in each run; and

means for prolonging the detecting of each said signal response at each of said cross-correlation frequencies until an integrated signal with a specific standard deviation has been acquired at each of said different cross-correlation frequencies;

said resultant signal deriving means comprising variable frequency digital filter means capable of being set to filter signal responses at substantially the cross-correlation frequencies.

10. The apparatus of claim 9 in which said digital filter means is capable of filtering with a bandwidth narrowing over time as a signal response is detected.

11. The apparatus of claim 10 in which the signal from said resultant signal deriving means is automatically amplified by automatic gain means without phase and modulation changes.

12. The apparatus of claim 11 in which the first and second frequencies are each generated by frequency synthesizer means, the frequency of the difference between said first and second frequencies being essentially 50 to 1000 hertz.

13. The apparatus of claim 12 in which means are provided for synchronizing the acquisition of data waveforms sensed by said resultant signal deriving means in each run with the phase of the signal modulating the electromagnetic radiation of said first frequency, and for superimposing corresponding segments of said waveforms thus sensed to obtain an average waveform value for each run having an increased signal to noise ratio over the individual waveform segments.

14. In apparatus for cross-correlation frequency domain fluorometry-phosphorimetry, which comprises:

a source of electromagnetic radiation;

means for amplitude modulating the electromagnetic radiation at a first frequency;

means for directing the amplitude-modulated electromagnetic radiation at a sample;

means for detecting the luminescence of the sample;

means for providing a signal coherent with amplitude modulated signals produced by said amplitude modulating means, at a second frequency, to said detecting means;

means for modulating the gain of said detecting means or multiplying the output by said detecting means by said signal;

said second frequency being different from said first frequency; and

means for deriving a resultant signal from said electromagnetic radiation and said detecting means at a frequency of the difference between said first and second frequencies, to detect phase shift and modulation changes of said luminescence from that of said electromagnetic radiation;

the improvement comprising, in combination;

means for synchronizing the acquisition of data waveforms sensed by said resultant signal deriving means in each run, with the phase of the signal modulating the electromagnetic radiation at said first frequency, and for superimposing corresponding segments of said waveforms thus sensed to obtain an average waveform value for each run having an increased signal to noise ratio over the individual waveform segments, said synchronizing means comprising variable bandwidth digital filter means.

15. The apparatus of claim 14 in which said first and second frequencies are each generated by frequency synthesizer means, the frequency of the difference between said first and second frequencies being essentially 100 to 1000 hertz.

16. In a method for frequency domain cross-correlation fluorometry-phosphorimetry which comprises the steps of:

providing a source of electromagnetic radiation;

amplitude modulating the electromagnetic radiation at a first frequency;

directing the amplitude-modulated electromagnetic radiation at a sample;

detecting with a detector the luminescence of the sample while modulating the gain of said detector or multiplying the output of said detector with a signal at a second frequency to said detector;

with said signal at a second frequency being coherent with the modulation of said electromagnetic radiation and said second frequency being different from said first frequency; and

deriving a resultant signal from said electromagnetic radiation and said detector at a frequency of the difference between said first and second frequencies, to detect phase shift and modulation of said luminescence from that of said electromagnetic radiation;

the improvement comprising, in combination;

sequentially and automatically performing runs of said cross-correlation frequency domain fluorometry-phosphorimetry at sequentially differing values of said first and second frequencies;

detecting the intensities of signal responses of said runs at the respective frequency which is the difference of the respective first and second frequencies of each run; and

prolonging the time of said detecting of each signal response at each of said different first and second frequencies until an integrated signal with a specific standard deviation has been acquired at each of said differing first and second frequencies.

17. The method of claim 16 including the step of synchronizing the acquisition of data waveforms sensed by deriving said resultant signal, and superimposing corresponding segments of said waveforms to obtain an average waveform value for each run having an increased signal to noise ratio over the individual waveform segments.

18. The method of claim 17 in which said resultant signal is derived by means comprising variable frequency digital filter means.

19. The method of claim 18 in which said digital filter means is set to filter signal responses at substantially a third frequency which is essentially the difference of the respective first and second frequencies used.

20. The method of claim 19 in which said third frequency is at least substantially 100 to 1000 hertz.

21. The method of claim 19 in which said digital filter means is capable of filtering with a narrowing over time bandwidth as a signal response is detected.

22. The method of claim 19 in which the resultant signal is automatically amplified by automatic gain means without phase and modulation changes.

23. The method of claim 19 in which said first and second frequencies are varied from run to run on a logarithmic scale, with the difference between said first and second frequencies being substantially constant.

24. In a method for frequency domain cross-correlation fluorometry-phosphorimetry which comprises the steps of:

providing a source of electromagnetic radiation;

amplitude modulating the electromagnetic radiation at a first frequency;

directing the amplitude-modulated electromagnetic radiation at a sample;

detecting with a detector the luminescence of the sample while modulating the gain or multiplying the output of said detector with a signal at a second frequency to said detector;

with said signal at a second frequency being coherent with the modulation of said electromagnetic radiation and said second frequency being different from said first frequency; and

deriving a resultant signal from said electromagnetic radiation and said detector at a frequency of the difference between said first and second frequencies, to detect phase shift and modulation of said luminescence from that of said electromagnetic radiation;

the improvement comprising, in combination;

sequentially and automatically performing runs of said cross-correlation frequency domain fluorometry at sequentially differing values of said first and second frequencies;

in which said resultant signal is derived by means comprising variable frequency digital filter means set to filter signal responses at substantially a third frequency which is the difference of the respective first and second frequencies used.

25. The method of claim 24 in which said third frequency is substantially 100 to 1000 hertz, said digital filter means being capable of filtering with a narrowing over time bandwidth as a signal response is detected.

26. The method of claim 24 in which the signal from said resultant signal deriving means is automatically amplified by automatic gain means without phase change.

27. The method of claim 24 including the step of synchronizing the acquisition of data waveforms sensed by deriving said resultant signal, and superimposing corresponding segments of said waveforms to obtain an average waveform value for each run having an increased signal to noise ratio over the individual waveform segments.