LC COLUMN HANDLING USING WEIGHTED COUNTERS

Abstract

The present invention relates to a method for operating a chromatography column comprising (a) providing a first value of a lifetime (first lifetime value) of said chromatography column; (b) performing a chromatographic separation of a sample on said chromatography column; (c) providing a value of a weighted aging factor determined based on at least one aging parameter selected from sample type, sample dilution, and sample volume; and (d) determining a second value of said lifetime (second lifetime value) of said chromatography column based on said first lifetime value and said weighted aging factor. The present invention also relates to further methods, databases, devices, and uses related thereto.

Claims

1. A method for operating a chromatography column, the method comprising: providing a first value of a lifetime of said chromatography column; performing a chromatographic separation of a sample on said chromatography column; providing a value of a weighted aging factor determined based on at least one aging parameter selected from sample type, sample dilution, and sample volume; and determining a second value of said lifetime of said chromatography column based on said first value and said value of the weighted aging factor.

2. The method of claim 1, wherein said sample type is defined by sample matrix and/or pre-purification state of said sample.

3. The method of claim 1, wherein said value of the weighted aging factor is calculated based on at least one further aging parameter selected from time since a preceding use, storage conditions since a preceding use, and set of chromatography conditions applied.

4. The method of claim 1, wherein said aging parameters are combined into a single, assay-specific weighted aging factor.

5. The method of claim 1, wherein further comprising comparing said second value to a reference value.

6. The method of claim 5, wherein a use of said chromatography column is discontinued or modified based on the result of comparing aid second value to said reference value; and wherein said modified use comprises at least one of repacking said chromatography column or reserving said chromatography column for applications in which lower performance is required.

7. The method of claim 1, wherein said weighted aging factor is calculated as a product of a sample type aging parameter, a sample dilution aging parameter, and a sample volume aging parameter.

8. The method of claim 7, wherein said second value is calculated as the first value in addition to or less the weighted aging factor.

9. The method of claim 1, wherein providing said first value of said column is based on an initial value of said lifetime and the weighted aging factors of any preceding uses of said chromatography column.

10. The method of claim 1, wherein determining the second value is further based on at least one of: (i) a parameter indicating the initial performance of said chromatography column; (ii) a parameter indicating the performance requirement of the assay used; (iii) a parameter indicating current performance of said chromatography column; and (iv) a parameter indicating onboard aging.

11. (canceled)

12. The method of claim 1, wherein providing the value of aid weighted aging factor comprises providing a value of a weighted aging factor determined based on (i) at least one sample specific aging parameter selected from sample type, sample dilution, and sample volume; and (ii) at least one operation specific aging parameter.

13. The method of claim 12, wherein said operation specific aging parameter is at least one of an assay specific parameter, a time since a preceding use, storage conditions since a preceding use, or a parameter indicative of a solvent exchange.

14. The method of claim 13, wherein said assay specific parameter is at least one of an eluent pH or a pressure condition.

15. A method of generating annotated aging parameter categories and aging parameter factors, for a chromatography column, the method comprising determining at least one first value of a performance parameter of the chromatography column; performing at least one chromatographic separation under conditions of a first set of aging parameter category values; determining at least one second value of said performance parameter; performing at least one, chromatographic separation under conditions of a second set of aging parameter category values, wherein said second set of aging parameter category values is non-identical to said first set of aging parameter category values; determining at least one third value of said performance parameter; and determining, based on said first, second, and third performance parameters and on said first and second set of aging parameter category values, a value of an aging parameter factor for at least one aging parameter category and annotating the values of said at least one aging parameter category and said aging parameter factor into a data collection.

16. (canceled)

17. A device for determining a second lifetime value of a chromatography column, comprising: a storage medium comprising a data collection tangibly embedded therein, said data collection comprising: at least one set of an aging parameter factor value annotated to an aging parameter category value, wherein said aging parameter category value comprises at least one category value of an aging parameter selected from sample type, sample dilution, and sample volume; and at least one of a first lifetime value of said chromatography column or an initial lifetime value of said chromatography column, an input unit that receives input data indicative of at least one aging parameter factor value; and a data processing unit that calculates a second lifetime value of said chromatography column based on at least one of said input data indicative of at least one aging parameter factor value, said first lifetime value of said chromatography column, or said initial lifetime value of said chromatography column.

18. (canceled)

19. The method of claim 10, wherein the parameter indicating the initial performance of said chromatography column is determined upon released testing.

20. The method of claim 10, wherein the parameter indicating onboard aging is indicative of at least one of time or temperature of column keeping.

21. The method of claim 17, wherein the aging parameter factor value is further annotated to a chromatographic protocol.

Description

FIGURE LEGENDS

[0223] FIG. 1: Schematic representation of an exemplary method of the invention.

[0224] FIG. 2: Factor contributing to chromatography column lifetime; a assay specific measurement adjustment factor (Sample amount, sample type, sample preparation. LC elution), β: onboard aging adjustment; & continuous prediction of column lifetime; γ initial prediction of column lifetime.

[0225] FIG. 3: Exemplary plot of remaining lifetime values over number of injections along with a regression line predicting end of usability of the column.

[0226] The following Examples shall merely illustrate the invention. They shall not be construed, whatsoever, to limit the scope of the invention.

EXAMPLE 1

[0227] To overcome the shortcomings of the prior art, in particular of simple lifetime counters, the invention proposes the use of a weighted counter, optionally with several additional adjustment factors. This weighted counter takes into consideration the stress each individually injected sample has onto the column. Individual factors for different column aging effects may be stored in a databank and/or determined continuously.

[0228] Factors like the matrix type, sample preparation, sample dilution, and injection volume may be combined into one factor for each assay. e.g. as an assay weighting factor. The column lifetime after each injection is then adjusted by the assay-specific weighting factor. Since different assays can tolerate different stages of column aging, each assay may have its individual limit of measurements. These two factors define the lifetime of a column per assay and the described proceeding supports performing multiple assays on one column type.

[0229] Both of the aforesaid factors may be determined experimentally and stored in a database. In a multi-column setup (LC multiplexing), a column can be used for less demanding assays, while the lifetime of the column for a more demanding assay is reached and this assay is measured on a new column.

[0230] To take into account the individuality of each column, an adjustment factor (e.g. determined by release testing), which has impact on the maximum number of available measurements may additionally be used. Also, monitoring of chromatographic parameters (like retention time or resolution) can be used for a column usage factor which continuously adjusts the maximum number of injections dependent on the current column performance. This factor corrects for effects from individual samples. Both these factors may be determined by measurements carried out on the specific column. The adjustment factor for column individuality can be determined before column shipment and added to the database together with individual column properties, or it can be determined directly after column installation and be then written to the database. Determination of the adjustment factor for individual column usage may be done continuously during column usage and the factor directly adjusts the weighted counter.

[0231] Column onboard time can also have an impact on the column lifetime. Therefore, a factor for column onboard aging (e.g. exposure to elevated temperature) can be applied onto the lifetime calculation. This factor may be determined experimentally and stored in a database.

[0232] The aforesaid factors, alone or in combination, may be used to improve assay-dependent usage of a column. In a multi-column system, the instrument can switch demanding assays to a new column at the end of the lifetime of a column. During use, the user can be informed about the column health and remaining column lifetime with a display (e.g. a bar for the column lifetime).

EXAMPLE 2

[0233] In an experiment, columns of the same type were used for different assays. The first column was subjected to injections with undiluted matrix samples, representing an assay for which a high sensitivity is required. After 7M) injections, the column was no longer usable.

[0234] For comparison, the matrix was diluted and injected to another column from the same batch as the first one with the same acquisition method. This represented an assay of an analyte which is present in a patient sample in a high concentration and therefore the sample may be diluted before the assay. With the diluted matrix samples, column lifetime was 2300 injections.

[0235] In conclusion, an injection with an undiluted matrix has to be weighted with a factor of 3.29 times higher than an injection using a diluted matrix sample.

EXAMPLE 3

[0236] Referring to FIG. 1, an exemplary embodiment of a method of the invention is shown. After the method is started 10, a first lifetime value is provided 20 and a chromatographic separation is performed 30. Based on at least one aging parameter selected from sample type, sample dilution, and sample volume, a value of a weighted aging factor is determined 40. The weighted aging factor may e.g. be calculated based on an aging parameter factor, which may be retrieved from a data collection 50. As will be understood, the information required for said retrieval may be entered by a user, or may be provided e.g. by selection of the assay to be performed. Based on the weighted aging factor, a second lifetime value is calculated 60, which may be compared to a reference 70. Depending on the outcome of the comparison, the column use may end 80, or may continue with a further use, wherein the second lifetime value of step 60 may be used as the first lifetime value in step 20 of the next separation.

EXAMPLE 4

[0237] Referring to FIG. 2, several factors may contribute to chromatography column lifetime, in an embodiment as specified herein above. Based on the factors described, a lifetime can be calculated according to equ. (10):

R.sub.ij+1=R.sub.m0×γ.sub.i×δ.sub.ij−1×a.sub.k−βm×(t.sub.ij−t.sub.ij-1)  (10),

with

TABLE-US-00001 R column lifetime counts i individual column i = 1, . . . , I j individual injection j = 0, . . . , J k individual assay k = 1, . . . , K m column type m = 1, . . . , M

EXAMPLE 5

[0238] A Table showing exemplary values of aging parameters and weighted aging factors and remaining lifetime values is shown in Table 1. FIG. 3 shows an exemplary use of the methods of the present invention in predicting end of usability of a chromatography column.

TABLE-US-00002 TABLE 1 Weighted Sample Injection Pressure Solvent Standby aging Remaining Assay Sample preparation vol. Eluent pH conditions exchange time factor lifetime Steroids in Serum +4 Enrichment 20 μL Acidic +1 High +3 No 0 None 0 +16 9984 Serum *2 *1.5 Opioids in Urine +3 Depletion 1:10 1 μL Basic +6 High +3 Yes +2 None 0 +11.6 9972 urine *0.1 *1.1 Vitamin D Whole Depletion 1:1 20 μL Neutral +4 Low +1 Yes +2 None 0 +11.5 9960 in whole blood +6 *0.5 *1.5 blood Standby 0 0 0 0 0 0 16 hours +16 +16 9944 over night

REFERENCE SIGNS

[0239] 10 start [0240] 20 provision of first lifetime value [0241] 30 chromatographic separation [0242] 40 providing a value of a weighted aging factor [0243] 50 data collection [0244] 60 determination of second lifetime value [0245] 70 second lifetime value exceeds reference? (y: yes, n: no) [0246] 80 end of column use

LITERATURE

[0247] EP 2,771,683 A1 [0248] EP 2,338,049 A1 [0249] EP 2,880,437 A1 [0250] U.S. Pat. No. 8,279,072 B2