Patent GB-1090438-A (GB)
Title: Indicating the quantities of the constituents of a sample from chromatographic curves
Inventor: HOLY HAROLD WALTER
IPC: G01N30/86
Filed: 1965-01-05
Abstract: In a liquid chromatographic analysis system an unknown liquid sample containing, e.g. aminoacids is passed into a chromatographic column and a buffer solution is subsequently passed through and treated with a colour reagent.  The stream is passed through a cell wherein its light transmittance is recorded as a peaked curve on a strip traversed laterally at constant speed.  A known quantity of a constituent not present in the sample mixture is added thereto before analysis, and the apparatus is standardised by making a further record from a standard mixture of known quantities of the constituents of the sample, also containing the known quantity of the constituent not occurring therein.  It is shown that <FORM:1090438/B1-B2/1> where q1 is the total unknown quantity of an amino acid represented by a particular curve peak.  qs1 is a known quantity of such aminoacid in standardisation  A1 is the area of the curve peak corresponding to q1  As1 is the area of the curve peak corresponding to qs1.  A1 is the area of curve peak due to a known quantity of a known amino acid not normally present in the unknown mixture.  <FORM:1090438/B1-B2/2> is the colour equivalent for each amino acid.  The curves are recorded on paper strips which are motor traversed laterally at constant speed (Figs. 7, 8, not shown), and a stylus is manually adjustable to follow each peak in succession while adjusting the slider of a potentiometer 14, in accordance with the curve excursion normal to the direction of traverse.  A low resistance source 10 is alternately connectible (Fig. 6) to a variable resistance 34 introducing an adjustable factor representing the standard area ratio, and a standard resistance 32 over switch 30; in series with a standard resistance 12 and a switch 38 alternately inserting or removing a resistor 40 to select either normal or double sensitivity.  A potentiometer 20 connected in series with resistor 42 across resistors 12, 40 is adjustable to introduce the colour equivalent factor, and potentiometer 60 substracts an adjustible potential from the output thereof to zeroize the curve base. Potentiometer 16 varied with the excursion of the curve peaks produces an output which is amplified at 48 to drive an integrating motor generator balance circuit combination 50, 52 driving a counter 54 reading proportionally to area of curve traced.  In operation a standard mixture is introduced into the chormatographic system to produce a standard curve of plural peaks, the area of each being proportional to the quantities of the respective constituents, and a sample mixture is introduced to produce a similar sample curve.  The standard curve is traversed past the stylus which is adjusted to follow the peaks thereof with switch 30 inserting standard resistor 32 and switch 38 inserting resistor 12, while the colour equivalent ratio potentiometer is set to unity.  The base of the curve is zeroized and each curve is traced with the stylus.  After each tracing, the count is recorded and the counter reset, and the ratios of the areas of the known constituents to that of an additional known constituent are determined.  The sample curve is similarly traversed, and the curve corresponding to the additional known constituent is traced. If the sensitivity of the system is identical for both standard and sample runs, and the quantities of additional known constituents are identical, the areas corresponding to the latter are identical and the ratio of these areas is determined and set into potentiometer 18 for the remainder of the sample run, and switch 30 is set to connect this potentiometer in circuit.  The colour equivalent ratio for the next known constituent to be assessed in the sample is set into potentiometer 46 and the area of the peaks corresponding thereto is measured.  Successive constituent colour ratios are set in for successive constituents and the aeras of the corresponding peaks are measured.  There is reference to liquid chromatography of peptides and of sugars.  The system is applicable to gas chormatography.