A SOLUTION FOR CONTROLLING THE PERFORMANCE OF THE IONIC EXCHANGE CHROMATOGRAPHY COLUMN OF HPLC (HIGH PERFORMANCE LIQUID CHROMATOGRAPHY) APPARATUSES, AND A PROCESS FOR PREPARING THE SAME

Abstract: A solution for controlling the performance of the ionic exchange chromatography column of HPLC apparatuses, and more particularly of the AUTO A1C HA 8110-8111 apparatus with a MICROPEARL S-F-W-A1C column, said solution being made up of a lyophilic hemolysate comprising hemoglobin, monobasic potassium phosphate, dibasic potassium phosphate, α-D-ribose, guanine, cytosine, thymine and uracil, and a solvent, for restoring the lyophilic hemolysate, com­ prising a nonionic surface active agent such as TRITON X-100, a bacteriostatic agent, such as for instance sodium azide, and water, and it also relates to a process for the production of said solution.

Description: The present invention relates to a solution for controlling the performance of the ionic exchange chromatography column of HPLC apparatuses, as well as to a process for the preparation of said solution. More particularly, this invention relates to a lyophilic hemolysate obtained from washed red blood corpuscles, and restored by means of a suitable solvent, for controlling the analytical system which is capable of determining the glycate hemoglobin HbA1C with the HPLC method by means of the device of the DAICHI company which is called "AUTO A1C HA 8110-8111" (R), with a column of the MICROPEARL S-F-W-A1C (R), so that the results obtained are always reliable and do not undergo changes due to the decay of the separation column. The column of the AUTO A1C HA 8110-8111 (R) device, according to the manufacturing company of the HPLC apparatus, is capable of working on about 1000 samples. On the contrary, a lower yield is obtained in many instances, due to losses of accuracy in the analytical determination, so that it is necessary to have at disposal a so-called "reference control samples". Various control hemolysates, and in particular the Lyphochek® Hemoglobin A 1c Control Human produced by B10-RAD, are commercially available at the present time, which satisfy at a high degree the needs of the particular column of the HPLC apparatus for which they have been prepared. On the contrary, said control hemolysates which are already available damage the column of the AUTO A1C HA 8110-HA 8111 (R) device, making its average useful life shorter. Moreover, such control samples, once they have been restored, have not an optimal dilution for the apparatus in question, so that they are to be adjusted before being processed. In addition, some of the control samples commercially available at the present time, when subjected to analyses, show, if they are employed on a MICROPEARL (R) column, anomalous separation peaks with respect to peaks obtained with the normal laboratory routine. More particularly, the lyophilization process carried out without suitable measures causes a decay of hemoglobin that shows, when analyzing the sample with HPLC, with a remarkable increase in the so-called "a+b" fraction which gives such standard a number of features different from those of the normal control samples. Such effect is particularly evident if the Figures 1, 2 and 3 are observed, said Figures showing, respectively, the plots of the results obtained employing on the HPLC apparatus the above mentioned control standard commercially available, and the results obtained analyzing routine samples in a physiologic and in a pathologic patient. Thus, the lack derives from the above of what is to be considered as the main feature of a control standard: i.e., a behaviour as similar as possible to the behaviour of a routine sample. According to the above, it is quite evident that it is very important to have at disposal a control solution such as that suggested by the Applicant, which solves the problems mentioned above suggesting the realization of a solution of the type mentioned for monitoring the AUTO A1C (R) device. It is another object of the present invention the realization of a control solution as mentioned above which is characterized by a high dilution of the red blood cells in the lyophilic hemolysate, about 1 cm³ of red cells/50 ml of the buffer solution, so that a high number of vials can be prepared with a very small amount of blood. It is a further object of the invention the realization of a control solution that is obtainable employing animal blood in general. Accordingly, it is a specific object of the present invention a solution for controlling the performance of the ionic exchange chromatography column of HPLC (High Performance Liquid Chromatography) apparatuses, and in particular of AUTO A1C HA 8110-8111 (R) apparatuses with MICROPEARL S-F-W-A1C (R) columns, said solution being made up of a lyophilic hemolysate comprising hemoglobin in amounts of 8.0 x 10⁻⁴ g (± 50 %), monobasic potassium phosphate in amounts of 9 x 10⁻⁴ g (± 50 %), dibasic potassium phosphate in amounts of 3 x 10⁻⁴ g (±50 %), as well as of a solvent comprising a nonionic surface active agent in amounts of 1.5 x 10⁻³ g (± 50 %), sodium azide in amounts of 3 x 10⁻⁴ g (± 50 %), and water in amount of 1.5 ml. Said lyophilic hemolisate of the solution according to the present invention also comprises α-D-ribose in amounts of 2.5 x 10⁻⁶ g (± 50 %) and preferably of 2.5 x 10⁻⁶ g. Again according to the present invention, said lyophilic hemolysate also contains at least one of the bases cytosine, thymine, guanine and uracil, in such amounts as to contain a total of 4.7 x 10⁻⁴ (± 50 %) micromoles. Preferably, at least two bases will be present, selected from among cytosine, guanine, thymine and uracil, in such amounts that the total amount contained is within the limits mentioned above. The solution of the present invention, said lyophilic hemolizate, contains cytosine in amounts of 1.35 x 10⁻⁴ (± 50 %) micromoles, guanine in amounts of 0.94 x 10⁻⁴ (± 50 %) micromoles, thymine in amounts of 0.93 x 10⁻⁴ (± 50 %) micromoles, and uracil in amounts of 1.49 x 10⁻⁴ (± 50 %) micromoles. Further according to the present invention said nonionic surface active agent consists of TRITON (Registered Trade Mark) X-100 in amounts of 1.5 x 10⁻³ g (± 50 %), and preferably of 1.5 x 10⁻³ g, while sodium azide is present in amount of 3 x 10⁻⁴ g. A composition of the control solution according to the present invention which is particularly preferred comprises a lyophilic hemolysate that is made of: 8 x 10⁻⁴ g of hemoglobin; 9 x 10⁻⁴ g of monobasic potassium phosphate; 3 x 10⁻⁴ g of dibasic potassium phosphate; 2.5 x 10⁻⁶ g of α-D-ribose; 0.94 x 10⁻⁴ micromoles of guanine; 1.35 x 10⁻⁴ micromoles of cytosine; 0.93 x 10⁻⁴ micromoles of thymine; 1.49 x 10⁻⁴ micromoles of uracil; and a solvent which consists of: 1.5 x 10⁻³ g of TRITON X-100; 3 x 10⁻⁴ g of sodium azide; 1.5 ml of water. The presence of the surface active agent and of the bacteriostatic agent serves the purpose of dissolving the stromata that are formed in the lyophilic hemolysate. Moreover, the scope of the present invention also contemplates a process for the preparation of the control solution disclosed above, said process comprising the steps of: treating the whole blood with an anti-coagulating agent; centrifuging at 150 G for ten minutes; removing the plasma; adding a physiologic solution in amounts between 4 and 10 ml; centrifuging; repeating the centrifugation till a clear supernatant is obtained; suspending the red blood cells in the physiologic solution for 24 hours; centrifuging and removing the top part, so obtaining the red blood cells washed; preparing the stabilizing solution; adding 50 microlitres of said solution for each ml of the red blood cells and homogenizing the whole mass gently; diluting the red blood cells + stabilizing solution at a ratio of 1/50 into a solution of monobasic potassium phosphate, dibasic potassium phosphate and water; keeping at rest for about 60 minutes; filling the solution into small vials and putting the same into the freeze-drying apparatus till a moisture less than 2 % is obtained; restoring the lyophilic hemolysate so obtained with a solution of a nonionic surface active agent, a bacteriostatic agent and water. PREPARATION EXAMPLE 10 ml of whole blood treated with an anti-coagulating agent are centrifuged at 150 G for 10 minutes. Then the plasma is removed. 5 ml of physiologic solution is then added and the whole mass is centrifuged. The operation is repeated till a clear supernatant is obtained. The erythrocytes are then suspended in the physiologic solution for 24 hours. The mass is centrifuged again and the top part is removed. Thus the washed erythrocytes are obtained as the residue. Separately the stabilizing agent is prepared, which consists of: α-D-ribose 10 g cytosine 0.060 g guanine 0.057 g thymine 0.047 g uracil 0.067 g water q.s. to 1 l 50 microlitres of that solution is added for each ml of red cells. The red blood cells are then homogenized with the solution gently and then they are diluted (erythrocytes + stabilizing) in the ratio 1/50 with a solution of 3.600 g of KH₂PO₄, 1.2 g of K₂HPO₄ and water q.s. to 1 l. As a result, the erythrocytes become hemolyzed with liberation of hemoglobin. The material is kept at rest for 60 minutes, then it is filled into small vials with 0.250 ml, and the vials are put into the freeze-drying unit till the obtainment of a moisture content less than 2 %. For employment, the lyophilic hemolysate is restored with 1.5 ml of a solution consisting of TRITON (Registered Trade Mark) X-100 (1.0 g), NaN₃ (2.0 g) and water q.s. to 1 l. Figures 4 and 5 show the plots obtained employing the control solution according to the present invention respectively in the case of physiologic and of pathologic values.

Claims: A solution for controlling the performance of the ionic exchange chromatography column of AUTO A1C HA 8110-8111® apparatuses with MICROPEARL S-F-W-AIC® columns, said solution being characterized in that it is made up of a lyophilic hemolysate comprising hemoglobin in amounts of 8.0 x 10⁻⁴ g (± 50 %), monobasic potassium phosphate in amounts of 9 x 10⁻⁴ g (± 50 %), dibasic potassium phosphate in amounts of 3 x 10⁻⁴ g (±50 %), α-D-ribose in amounts of 2.5 x 10⁻⁶ g (± 50 %), at least one base selected from among cytosine, thymine, guanine and uracil, in such amounts as to have a total amount of 4.7 x 10⁻⁴ (± 50 %) micromoles as well as of a solvent comprising a nonionic surface active agent in amounts of 1.5 x 10⁻³ g (± 50 %), sodium azide in amounts of 3 x 10⁻⁴ g (± 50 %), and water in the amount of 1.5 ml. A control solution according to claim 1, characterized in that it comprises α-D-ribose in the amount of 2.5 x 10⁻⁶ g. A control solution according to claim 1, characterized in that at least two bases are present selected from cytosine, guanine, thymine and uracil in such amounts that the total value is of 4.7 x 10⁻⁴ (± 50 %) micromoles. A control solution according to claim 1, characterized in that it comprises cytosine in amounts of 1.35 x 10⁻⁴ (± 50 %) micromoles, guanine in amounts of 0.94 x 10⁻⁴ (± 50 %) micromoles, thymine in amounts of 0.93 x 10⁻⁴ (± 50 %) micromoles, and uracil in amounts of 1.49 x 10⁻⁴ (± 50 %) micromoles. A control solution according to claim 1, characterized in that said nonionic surface active agent consists of TRITON (Registered Trade Mark) X-100 in amounts of 1.5 x 10⁻³ g (± 50 %). A control solution according to claims 1 and 5, characterized in that said solvent comprises 1.5 x 10⁻³ g of TRIT0N R X-100 and 3 x 10⁻⁴ g of sodium azide. A control solution according to each one of the preceding claims, characterized in that it comprises a lyophilic hemolysate made up of 8 x 10⁻⁴ g of hemoglobin, 9 x 10⁻⁴ g of monobasic potassium phosphate, 3 x 10⁻⁴ of dibasic potassium phosphate, 2.5 x 10⁻⁶ g of α-D-ribose, 0.94 x 10⁻⁴ micromoles of guanine, 1.35 x 10⁻⁴ micromoles of cytosine, 0.93 x 10⁻⁴ micromoles of thymine and 1.49 x 10⁻⁴ micromoles of uracil; and a solvent consisting of 1.5 x 10⁻³ g of TRITON R X-100, 3 x 10⁻⁴ g of sodium azide and 1.5 ml of water. A process for the preparation of the control solution claimed in any one of the preceding claims, said process being characterized in that it comprises the steps of: treating the whole blood with an anti-coagulating agent; centrifuging at 150 g for ten minutes; removing the plasma; adding a physiologic solution in amounts between 4 and 10 ml; repeating the centrifugation till a clear supernatant is obtained; suspending the erythrocytes in the physiologic solution for 24 hours; centrifuging and removing the top portion, so obtaining the erythrocytes washed; preparing the stabilizing solution containing α-D-ribose and at least one base selected from among cytosine, thymine, guanine and uracil; adding 50 microlitres of said solution for each ml of red blood cells and homogenizing the whole mass gently; diluting the solution of erythrocytes + stabilizing agent in the ratio of 1/50 with a solution of monobasic potassium phosphate, dibasic potassium phosphate and water; keeping the solution at rest for about 60 minutes; filling the same into small vials and putting the vials into the freeze-drying unit till obtaining a moisture content less than 2 %; and restoring the lyophilic hemolysate so obtained with a solution of a nonionic surface active agent, a bacteriostatic agent and water.

Inventors: BASAGNI, UMBERTO, BONICOLINI, FRANCESCO
Applicants: A. MENARINI S.A.S.
Application year: 1988
Main classification: G01N33
IPC codes: G01N30, G01N33, B01D15