Patent GB-982497-A (GB)
Title: Improvements relating to chromatography
IPC: G01N30/86
Filed: 1963-06-06
Abstract: 982,497. Recording apparatus. E. PALM. June 6, 1963 [June 6, 1962], N. 22638/63. Heading G1J. Recording apparatus for use with gas chromatography equipment for providing a record of the detection of components of a sample injected into a separating column of the equipment, includes a device for marking the record with information from which the components may be identified, a drive unit for producing an output changing at a rate inversely proportional to the time elapsing from an instant occurring between the time of sample injection and the time of detection of a selected component, and connections for applying the output to the marking device so that each marking is significant of the value of the output at the time of detection of a component corresponding to that marking. The record may be in the form of a chart mounted on a drum, the chart being moved past the marking device at a speed which decreases logarithmically with time from the instant referred to above this instant being calculated as described in the Specification and being the instant at which the sample enters the effective part of the column, allowing for the dead space at the beginning of the column, this dead space in most cases also including a variable part of the actual column volume itself depending on various conditions. Although the time scale is related to this instant, the chart movement is not actually started until the "air peak", i.e. the peak produced by components that are not retained by the column, is detected by the marking device. Thus, in use a sample is injected into the chromotography equipment and after a certain time interval the sample enters the effective part of the separating column, this being the instant referred to above. The "air peak" is then produced the chart being set in motion at this point and subsequently peaks corresponding to the different components of the sample are marked on the chart. By marking on a time scale starting at the instant when the sample enters the effective part of the column a record is obtained which is easily correlated with other measurements even through these may have been made with different columns or at different temperatures. The chart may be driven from a motor either by using suitable profile cams or by using a variable potentiometer. The chart drive may be started manually or may be started automatically the "air peak" being arranged to operate a switch to start the drive at the required speed. In this case the gas stream through the equipment may be divided into two, one part going through the separating column and the other through an adjustable delay blind column to produce an "air peak" of greater intensity to ensure starting of the drive. As an alternative to the drum chart record, the record may be produced in the form of a list, a printing machine drum being mounted in place of the recording drum. The printing machine drum carries type denoting "interaction potential" values, these values being characteristic for each component, and being related to the energy required to separate by an infinite distance a molecule of the column material and a molecule of the component, the values also being used in the calculation of the instant serving as the time scale starting point. Thus, if desired, the printing drum may carry type denoting the component substance names as an alternative to or as well as type for the interaction potential values. The printing machine drum is mounted beside a digital printing mechanism for peak heights and paper to be printed on is moved past the drums which stamp on it simultaneously peak height (and thus concentration) and/or interaction potential values and/or substance name of each component as it is detected. Specification 916,919 is referred to.