the chromatography apparatus of the present invention is shown schematically in fig1 . the main parts of the apparatus are two syringes 1 and 3 which are used to control the flow of fluids around the system , a chromatography column 4 attached to a detector 13 , a sampling induction tube 5 , two hold - up loops 7 and 9 which hold a fixed , predetermined volume of liquid and two reservoirs 15 and 17 . the apparatus also includes a microprocessor which is used to control the syringes 1 and 3 via stepper motors and to control the various valves connecting the fluid parts together and to process and output the results from the detector 13 . the reservoirs for buffer solution can be either rigid plastic bottles or flexible aseptic containers similar to the well known wine boxes which have an outer box and inner collapsible bay . in use , the apparatus operates as follows . first , a sample is drawn up into the apparatus via the induction line 5 . ( this part of the apparatus is also shown in fig4 and 5 ). the sample is drawn up by syringe 1 via the two hold - up loops 7 and 9 . then valve 8 is closed to isolate the sample in hold - up loop 7 from the syringe while the sample in hold - up loop 9 is ejected as waste . this is done so that the sample in hold - up loop 7 which will actually be tested does not include the first fluid drawn from the sample which can be unsatisfactory for a number of reasons , e . g . because of contamination or air bubbles . subsequently , valve 8 is opened and syringe 1 pumps the sample onto the column 4 . various constituents of the sample will bind with different strengths to the packing material in the column . the two buffer reservoirs 15 and 17 contain buffers of different concentrations and the two syringes 1 and 3 are filled respectively from the two reservoirs . subsequently , under control of the microprocessor , the two syringes are driven so as to pump buffer solution to the mixing point 16 and from there through the column 4 . the concentration of the mixed solution is clearly dependent on the respective rates of the two syringes and the concentrations of the buffers and so it is possible for the concentration of the mixed solution to be varied by the microprocessor according to a pre - stored program . note that in the illustrated embodiment no mixing chamber is necessary , the solutions mix at the junction of the three tubes . a mixing chamber can be used if desired . alternatively , a gradient valve connected directly to pressurized reservoirs , e . g . syringes driven at the same rate , can be used to control the concentration of solution supplied to the column . when the concentration of the buffer reaches a sufficient strength to disassociate a particular sample constituent from the column packing material , then that constituent will pass out of the column and through the detector 13 where it can be detected . the microprocessor is conveniently programmed to increase the concentration of buffer passing through the column gradually in a series of defined steps or in a continuous gradient . thus , it will be known at any time exactly what concentration of buffer is passing through the column and , thus , which of these sample constituents is being disassociated from the column packing material and appearing in the detector . if this is done then by integrating the output of the detector , the amount of that constituent in the sample can be calculated and , thus , a quantitative result obtained . the detector used is similar to that used in previous low pressure liquid chromatography apparatus and simply measures the light absorption at a certain wavelength of the fluid passing through it . the output is supplied to the microprocessor controlling the apparatus which also processes and outputs the results . the results are displayed in graphical form both as a hard copy via printer 23 and on a video display 21 . an example of the results produced is shown in fig6 . the control apparatus is designed so that when the apparatus is switched on , a number of blank runs are performed , e . g . five , that is runs without a sample on the column so that air bubles and contaminants are removed from the system . the system is preferably arranged to continue performing blank runs until the column is ready for use . the same procedure is also used when the machine is shut down . the circuitry also counts the number of times the column is used so that a limit can be set on the life of the column . in the present case the limit is approximately 100 samples as opposed to known hplc columns which are typically used for anywhere from 1000 to 10000 assays requiring numerous washings during the life of the column . the chromatography column of the present invention is shown in more detail in fig3 . it comprises a two - part plastic body consisting of a lower part 31 and an upper part 33 . the two parts are formed so that they push - fit together in an interference fit by virtue of the wide , open - end of part 31 fitting around a portion 34 a reduced external diameter . an aperture 36 for fluid is provided in the end wall of the upper part 33 and a second aperture 35 is provided in the end wall of the lower part 31 ( or along the shoulder 54 in lower part 31a ). the apertures , otherwise referred to herein as inlets and outlets , are covered by permeable membranes 37 made from polyurethane or p . t . f . e . and the upper part 33 is filled with column packing material 38 by a process described below , the remainder of the volume in the column being made up by inert permeable material 39 . additionally , referring to fig7 an alternative lower part 31a useful in association with the upper part 33 as described with reference to fig3 is illustrated . under this alternative embodiment , the lower part 31a includes a shoulder 54 extending into a first chamber 60 wherein the shoulder is spaced between the upper and lower ends 56 and 58 , respectively , of the lower portion 31a . this arrangement provides for a second chamber 62 occurring below the shoulder 54 onto which one end of the mounting can extend to provide both a fluid tight seal along the aperture 35 and a more thoroughly packed column . the construction of the column allows a particularly simple method to be used for packing it . this method is relatively quick and suitable for automation and gives reliably packed columns . first , the polyurethane filter is placed in an inverted upper part 33 and an open ended cylinder or collar is fitted over and extends from the diameter reduced portion 34 . then , the column part 33 and collar are filled with a slurry containing a greater amount of packing material 38 than is required to fill the column and a vacuum applied to aperture 36 . this draws off the fluid and leaves the column packing material packed in the column part 33 and the collar . the collar is then twisted and removed leaving the column packing material standing proud of the end of the column part 33 , and an excess of packing material is sliced off . the lower part 31 ( or 31a depending on which is being used ) with its polyurethane filter 37 already in place and filled with inert porous material is fitted onto the upper part 33 to complete the column . the slicing of the excess packing material can be performed using a rotating cutter to leave a hump in the middle so that when the two parts of the column are pushed together the packing material is placed under compression . in an embodiment of the invention which is particularly suited for testing haemoglobins in blood , the column packing material used is polyaspartic acid bonded to silica beads . the completed column is fairly resistant to rough handling , particularly compared to prior art columns , and so used columns can be handled and replaced by relatively unskilled technicians , and replacement columns can be despatched to clinics by mail etc . furthermore , the columns can be produced relatively cheaply . the part of the chromatography apparatus which holds the column is shown in fig4 and 5 . it comprises a lower mounting 43 which includes a fluid path 44 through which fluid is supplied to the column and an upper mounting 45 including a fluid path 47 . the upper mounting includes an outer seat 46 which abuts the top corners of the column and an inner seat 46a which abuts and seals to the end of the column and surrounds the outlet from the column . fluid from the outlet of the column passes through the region within the inner seat 46a and via an outlet 47 to the main part of the apparatus . the upper mounting 45 is moveable between the illustrated lower position and an upper position in which the seats 46 and 46a are raised above the column so that the column can be lifted out of the apparatus through the opening 40 in the front . the mounting is moved by a cam arrangement 48 operated by handles 49 ( see fig5 ) and the operating surface 50 of the cam arrangement is configured so that the mounting will remain stationary in either of its positions . it will be recalled that the illustrated column is formed of two parts which push together , and it will , therefore , be appreciated that the pressure exerted on the column by the upper mounting when it is lowered tends to hold the column together . fig5 shows a rear view of the mounting part of the apparatus and more clearly shows the handles 49 of the cam arrangement . the sample induction part of the apparatus is shown in detail in fig2 . it is designed to take a sample from a standard medical vial 25 . the induction part includes a moveable lower platform 27 which is moveable between a raised position shown in full and a lowered position shown dotted and is urged towards its upper position by a spring 24 . it also includes an upper seat 28 through which the sample induction tube 5 extends . the vial is placed over the induction tube 5 with its upper edge near the seat 28 while the platform is held in its lowered position . the moveable platform 27 is allowed to rise to its upper position to support the lower part of the vial and hold the vial in position with its open end against the seat 28 . in the present embodiment , which is intended to be used with a method of collecting the samples which will be described below , the sample vial 25 will contain a capillary tube 26 ( originally used to collect the sample ). while the illustration shows the platform arranged to hold the vial vertically , in an alternative embodiment in order that this capillary tube does not impede the sample induction tube 5 , the platform is arranged so as to tilt the sample vial so that the capillary tube falls to one side and clears the sample inlet tube 5 . the present invention is particularly intended for use in analyzing blood samples and is designed to be suitable for use by operators with relatively little training . one of the main problems with prior art techniques as mentioned above , is the skill required to take a blood sample and prepare it so that it is suitable for analysis . the present invention , however , is designed to work with the blood sample taken in a particularly simple way and processed in a single solution process . according to the present invention , a blood sample is taken not by a syringe , but instead simply by pricking the patient &# 39 ; s finger and applying a capillary tube to the droplet of blood which emerges . the capillary tube in this embodiment has a volume of 20 microliters . the capillary tube is then placed in a standard sample vial containing a solution which dilutes and haemolises the blood . in this embodiment , the sample vials are pre - filled with 1 ml of the processing solution . different amounts can be used . no filtration or centrifuging of the resultant mixture is necessary ; the sample is simply agitated , e . g . shaken by hand , for a recommended time , e . g . not less than five minutes , and then placed in the sample induction part of the apparatus as described above . in an embodiment of the invention which is intended for testing the haemoglobins in blood samples , and particularly to test for glycated haemoglobins , the processing solution is one of the buffer solutions used in the elution process , in this case buffer a described below , and the vial needs to be agitated for not less than five minutes before being placed in the apparatus . the testing apparatus is programmed with a number of tests which it can carry out automatically on command of the operator . thus , it will be possible for a number of tests to be available , each selected by only one or two button operation . after the type of test has been entered and a &# 34 ; start &# 34 ; switch operated , the machine automatically executes the induction of the sample , testing and processing the results and displays the output in the required form . fig6 shows a typical output of a blood analysis for glycated haemoglobin . this was carried out using the apparatus described earlier and using the following two buffer solutions : the first large peak , labelled 2 , is glycated haemoglobins passing through the detector and the second peak 3 represents non - glycated haemoglobins passing through the detector . as can be seen from the table below the graph , the processing circuitry automatically works out the area of beneath of the peaks ( allowing for their overlap ), i . e . integrates the curve , and this represents the total amount of glycated haemoglobins in the sample . the processing circuitry in this embodiment is also programmed in this to look out for certain other peaks in the sample which might be representative of other haemoglobin abnormalities . the detector 13 can be provided with means for measuring at several different wavelengths , e . g . by using a tunable laser or by having several different fixed frequency light sources in it , or an achromatic light source with a number of interchangeable filters . thus , tests at several different wavelengths are available . thus , by using different buffer solutions and ( if necessary ) different column packing materials ( easily used by virtue of the easily replaceable column ) the apparatus can provide a wide variety of tests all of which are relatively simple for the operator to select . the syringes , column , fluid paths detector and displays and the electronic processing circuitry all form a single unit of such a size that it can be conveniently mounted on a desk top . the apparatus is , therefore , very suitable to use in individual clinics . a clinic would be provided with a supply of suitable buffer solutions , pre - filled sample vials and capillary tubes of the correct length for taking samples and a number of replacement columns . the supply of buffer solutions and column vials and capillary tubes could be replenished on demand or at regular intervals and all of the equipment is tough enough to withstand rough handling and are light and small enough so they can be despatched by mail etc . this means that individual clinics can make tests , e . g . blood tests , instantly on their own premises and thus have a blood test result within minutes of a sample being taken . further , the staff do not need specialist training in order to use the apparatus or replace the column etc . the equipment supplied to a clinic and the set of replacement materials can also include a standard sample ( in a marked vial ) which can be passed through the apparatus for quality control purposes . it would also be possible to run a blind quality control system in which samples whose composition is known only to the quality inspector are despatched to the clinics and the results returned to the inspector . the present invention , therefore , provides a relatively small circuit which is easy to use and could be used on an individual basis by clinics , hospitals and surgeries around the world . further , all of the parts which are used up during testing can be replenished easily , e . g . by dispatching a pack of columns , buffer solutions , pre - filled vials and capillary tubes to the user . the apparatus is also suitable for programming and performing a wide variety of tests for haemoglobin abnormalities . the volume of the capillary tube is 20 micro liters and the vials are pre - filled with the solution required to process the sample . the above description is given by way of example and numerous modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention which is defined by the claims appended hereto .