Methods and apparatuses for spectrophotometric determination of contents and turbidity of a liquid sample

A testing method for determining contents of liquids, said method comprising:

• (a) obtaining a subject liquid composed of multiple substances, at least one of which is a liquid component whose concentration is to be measured;
• (b) using a testing apparatus comprising a light source for transmitting light through said subject liquid along a light path of known length (L) therethrough, a spectrometer operable to measure an intensity of the light after travel thereof through said subject liquid on said light path, and one or more computing devices connected to said spectrometer to receive light intensity measurements therefrom, performing the following steps:
• (i) a liquid-absent measurement step comprising transmission of light along said light path in absence of any liquid substance, and measurement by the spectrometer of the intensity of said light after travel of said light along said light path in said absence of any liquid substance, thereby obtaining an liquid-absent light intensity measurement (Ie) from the spectrometer;
• (ii) a liquid-blank measurement step comprising transmission of light by said light source along said light path during occupancy of said light path by a pure unmixed volume of said liquid component, and measurement by the spectrometer of the intensity of said light after travel of said light along said light path and through said pure unmixed volume of said liquid component, thereby obtaining a liquid-blank light intensity measurement (Iw) from the spectrometer;
• (iii) a subject measurement step comprising transmission of light by said light source along said light path during occupancy of said light path by the subject liquid, and measurement by the spectrometer of the intensity of said light after travel along said light path and through said subject liquid, thereby obtaining a subject light intensity measurement (Is) from the spectrometer;
• (c) using said liquid-absent light intensity measurement (Ie), said liquid-blank light intensity measurement (Iw), and said subject light intensity Is measurement, calculation by the one or more computing devices of both a volume concentration of the liquid component in said subject liquid, and a liquid-corrected light intensity (Iwc);
• and
• (d) using said liquid-absent light intensity measurement Ie and said liquid-corrected light intensity (Iwc), calculation by the one or more computing devices of a color measurement of the subject liquid.

A testing method for determining contents of liquids, said method comprising:

• (a) obtaining a subject liquid composed of multiple substances, at least one of which is a liquid component whose concentration is to be measured;
• (b) using a testing apparatus comprising a light source for transmitting light through said subject liquid along a light path of known length (L) therethrough, a spectrometer operable to measure an intensity of the light after travel thereof through said subject liquid on said light path, and one or more computing devices connected to said spectrometer to receive light intensity measurements therefrom, performing the following steps:
• (i) a liquid-absent measurement step comprising transmission of light along said light path in absence of any liquid substance, and measurement by the spectrometer of the intensity of said light after travel of said light along said light path in said absence of any liquid substance, thereby obtaining an liquid-absent light intensity measurement (Ie) from the spectrometer;
• (ii) a liquid-blank measurement step comprising transmission of light by said light source along said light path during occupancy of said light path by a pure unmixed volume of said liquid component, and measurement by the spectrometer of the intensity of said light after travel of said light along said light path and through said pure unmixed volume of said liquid component, thereby obtaining a liquid-blank light intensity measurement (Iw) from the spectrometer:
• (iii) a subject measurement step comprising transmission of light by said light source along said light path during occupancy of said light path by the subject liquid, and measurement by the spectrometer of the intensity of said light after travel along said light path and through said subject liquid, thereby obtaining a subject light intensity measurement (Is) from the spectrometer;
• (c) using said liquid-absent light intensity measurement (Ie), said liquid-blank light intensity measurement (Iw), and said subject light intensity Is measurement, calculation by the one or more computing devices of both a volume concentration of the liquid component in said subject liquid, and a liquid-corrected light intensity (Iwc);
• and
• (d) determining a turbidity of the subject liquid by:
• calculation by the one or more computing devices of a pure-solvent optical density (OD0) using the liquid-blank light intensity measurement (Iw) and the liquid-absent light intensity measurement (Ie);
• calculation by the one or more computing devices of a subject optical density (ODs) using the subject light intensity measurement (Is) and the liquid-absent light intensity measurement (Ie);
• conversion by the one or more computing devices of the pure-solvent optical density (OD0) and subject optical density (ODs) to logarithmic wavelength scale, plotting by the one or more computing devices of plots of the pure-solvent optical density (OD0) and the subject optical density (ODs) in said logarithmic wavelength scale, and calculation by the one or more computing devices of at least one of either a slope difference (Δ Slope) and an intersection difference (Δ Int) between said plots of the pure-solvent optical density (OD0) and the subject optical density (ODs) in said logarithmic wavelength scale and in a wavelength range (WLR) in which optical density is attributable only to light scattering;
• and
• calculating turbidity of the subject liquid using either said slope difference (Δ Slope) or said intersection difference (Δ Int).

A testing method for determining contents of liquids, said method comprising:

• (a) obtaining a subject liquid composed of multiple substances, at least one of which is a liquid component whose concentration is to be measured;
• (b) using a testing apparatus comprising a light source for transmitting light through said subject liquid along a light path of known length (L) therethrough, a spectrometer operable to measure an intensity of the light after travel thereof through said subject liquid on said light path, and one or more computing devices connected to said spectrometer to receive light intensity measurements therefrom, performing the following steps:
• (i) a liquid-absent measurement step comprising transmission of light along said light path in absence of any liquid substance, and measurement by the spectrometer of the intensity of said light after travel of said light along said light path in said absence of any liquid substance, thereby obtaining an liquid-absent light intensity measurement (Ie) from the spectrometer;
• (ii) a liquid-blank measurement step comprising transmission of light by said light source along said light path during occupancy of said light path by a pure unmixed volume of said liquid component, and measurement by the spectrometer of the intensity of said light after travel of said light along said light path and through said pure unmixed volume of said liquid component, thereby obtaining a liquid-blank light intensity measurement (Iw) from the spectrometer;
• (iii) a subject measurement step comprising transmission of light by said light source along said light path during occupancy of said light path by the subject liquid, and measurement by the spectrometer of the intensity of said light after travel along said light path and through said subject liquid, thereby obtaining a subject light intensity measurement (Is) from the spectrometer;
• and
• (c) using said liquid-absent light intensity measurement (Ie), said liquid-blank light intensity measurement (Iw), and said subject light intensity Is measurement, calculation by the one or more computing devices of both a volume concentration of the liquid component in said subject liquid, and a liquid-corrected light intensity (Iwc);
• wherein step (c) comprises plotting by the one or more computing devices of a pure-solvent optical density spectrum plot (Awe) in a wavelength range WLR in which optical density is attributable to light scattering, calculation by the one or more computing devices of:
• a slope (SLPwe) and intercept (INTwe) of said pure-solvent optical density spectrum plot, a corrected pure-solvent optical density spectrum (ODwe-corr), where ODwe-corr(λ)=Awe(λ)−(SLPwe×λ+INTwe), and the volume concentration of solvent [Sol], where [Sol]=100×Ase(λ)/ODwe-corr(λ), or [Sol]=100×A′se(λ)/OD′we-corr(λ), and Ase(λ)=−log10{Is(λ)/Ie(λ)}.