Quantitative analytical method and apparatus for determining a plurality of ingredients with spectrometric analysis

A quantitative analytical spectrometric method of measuring a sample of exhaust gas on the basis of an absorption spectrum obtained to determine the concentration of formaldehyde and methanol, comprising the steps of:

• determining concentration ranges for various combinations of formaldehyde and methanol;
• determining frequency bands, used for a spectrometric analysis of formaldehyde and methanol for each various combination within an absorption wave number range of 2800 cm.sup.-1 to 2700 cm.sup.-1 ;
• storing the frequency bands and absorption wave number corresponding to each combination of formaldehyde and methanol;
• measuring the value of a sample across an absorption spectrum of the stored frequency bands;
• and
• using one of the frequency bands and the corresponding absorption wave numbers stored to calculate the concentration of formaldehyde and methanol.

A quantitative analytical method of using spectrometric analysis, in which a sample is irradiated with light, and a plurality of ingredients contained in the sample to be measured are quantitatively determined on the basis of absorptivities at a plurality of appointed wave number points in an absorption spectrum obtained at that time, comprising:

• establishing groups of ingredients to be measured suitable to a plurality of kinds of samples to be measured, those groups having ingredients which can be approximately estimated;
• determining groups of wave number points corresponding to the respective groups of ingredients;
• storing the groups of wave number points;
• determining a corresponding compensation data for each group of wave number points;
• storing the corresponding compensation data to compensate for any interference between ingredients;
• obtaining the value of a sample across an absorption spectrum containing the groups of wave number points;
• using one of the groups of wave number points to calculate the concentration of the values of the ingredients in the sample;
• and
• using a corresponding compensation data to compensate for any interference in the calculated concentration values.

A quantitative analytical method of using spectrometric analysis, in which a sample is irradiated with light, and a plurality of ingredients contained in the sample to be measured are quantitatively determined on the basis of absorptivities at a plurality of appointed wave number points in an absorption spectrum obtained at that time, comprising:

• establishing groups of ingredients to be measured suitable to a plurality of kinds of samples to be measured, those groups having ingredients which can be approximately estimated;
• determining groups of wave number points corresponding to the respective groups of ingredients;
• storing the groups of wave number points;
• measuring the value of a sample across an absorption spectrum containing the groups of wave number points;
• using one of the groups of wave number points to calculate the concentration of the values of the ingredients in the sample;
• compensating for the calculated concentration values by use of a reverse matrix calculation having a vector with a significant linear independency to reduce the effect of mutual interference between ingredients;
• determining if the calculated concentration of ingredients is appropriate for the group of wave number points used and if not, selecting a different group of stored wave number points until the appropriate group of wave number points is used to calculate the concentration of the ingredients;
• and
• providing the concentration of the ingredients.

A quantitative analytical method measuring the ingredients in an exhaust gas of using Fourier Transform infrared spectrometric analysis, in which a sample of an exhaust gas is irradiated with infrared light, and a plurality of ingredients contained in the sample to be measured are quantitatively determined on the basis of absorptivities at a plurality of appointed wave number points in an absorption spectrum obtained at that time, comprising:

• establishing separate matrixes for groups of ingredients to be measured suitable to a plurality of kinds of samples to be measured, those groups having ingredients which can be approximately estimated;
• determining groups of wave number points corresponding to the respective groups of ingredients;
• storing the groups of wave number points;
• irradiating a sample of exhaust gas with infrared light;
• measuring the absorption values of the sample across an absorption spectrum containing the groups of wave number points;
• selecting one of the matrixes and using one of the groups of wave number points to calculate the concentration of the values of the ingredients in the sample;
• compensating for the calculated concentration values by use of a reverse matrix calculation having a vector with a significant linear independency to reduce the effect of mutual interference between ingredients;
• determining if the calculated concentration of ingredients is appropriate for the group of wave number points used and if not, selecting a different group of stored wave number points until the appropriate group of wave number points is used to calculate the concentration of the ingredients;
• and
• providing the concentration of the ingredients.

A spectrometric apparatus for determining the constituent elements in an exhaust gas, comprising:

• a sample cell for holding a sample of an exhaust gas;
• means for irradiating the sample of the exhaust gas with infrared light;
• means for providing an interferogram representative of the sample of exhaust gas from the interaction of the infrared light;
• means for storing a plurality of matrixes of combinations of known constituent elements based on groups of wave number points;
• means for measuring the absorption values of the exhaust gas sample from the interferogram;
• means for calculating the concentration values of the constituent elements from the absorption values and one of the stored matrixes;
• means for compensating for the calculated concentration values by use of a reverse matrix calculation having a vector with a significant linear independency to reduce the effect of mutual interference between constituent elements;
• means for determining if the calculated concentration of constituent elements is appropriate for the matrix used and if not, selecting a different matrix until the appropriate group of wave number points is used to calculate the concentration of the constituent elements;
• and
• means for providing the concentration of the constituent elements.