Version 1.6.1
David Trew
Consulting Ltd
9 Data and Record Lifecycle
Understanding activities associated with the collection, processing, reporting and storage of records and data are key requirements in ensuring their reliability and trustworthiness. Once the lifecycle of a data process has been identified you then need to identify the how the integrity of the data or record could be compromised at each stage of that process. The final phase consists of developing and establishing controls designed to mitigate the potential for compromised data or records. This is illustrated in the following example.
9.1 Data Process Associated with HPLC Analysis
The determination of the amount of drug substance in a dosage form, such as a tablet, employing high performance liquid chromatography (HPLC) is one of the most routine analysis carried out in a pharmaceutical quality control laboratory. A typical HPLC analysis will consist of the following twelve step process, which need to be performed in the following order:
- Preparation of HPLC mobile phase
- Preparation of solvents for preparing sample and standard solutions
- Preparation of standard solutions, these are usually prepared in duplicate, and a standard recovery performed, to provide evidence that the standards have been correctly prepared.
- Preparation of system suitability solutions (if this is appropriate, as quite often the standard solutions are used to demonstrate the HPLC is operating correctly)
- HPLC method set up, includes setting the following parameters on the HPLC
Flow rate
Gradient profile (if applicable)
Run time
Injection volume
Sample temperature (if applicable)
Column temperature (if applicable)
Detector wavelength
Analyte retention time(s)
Integration parameters
Standard amount
- System suitability check. This should include injecting: Blank, Standards, and System suitability solution. This will confirm that the HPLC is uncontaminated, the standard solutions have been correctly prepared and the HPLC is functioning satisfactory.
- Sample preparation. This will normally entail weighing the sample.
- Injection sequence setup which will include:
Entry of sample and standard identity
Sample amounts
Sequence parameters such as sample dilution factors
Raw data and processed data file names
- HPLC analysis of samples. This will create a raw data file for each injection. All the raw data files in the same sequence should normally have the same base file name, and each individual file is identified by a sequential number
- Integration of peaks. This will create a processed data file for each injection. These should normally have the same name as the corresponding raw data files, but have different extension.
- Calibration by comparing the peak area in the sample chromatograms with the peak area in the standard chromatograms
- Calculation and reporting of analyte amounts. This will create a result file for each injection. As with the result files, these should normally have the same name as the corresponding raw data files, but have different extension.
The next stage is to identify how the data could be compromised at each step in the process. The principle data integrity concerns in the quality control laboratory is the either the falsification of data to conceal test results that show that the is out of specification (OOS) product batches, or using inappropriate manipulation of the raw data processing parameters to cause, an otherwise out of specification result, to yield a result that complies with acceptance criteria. The steps that could be manipulated to falsify results include steps 3 and 7 the preparation of standard and sample solutions, respectively, and steps 5 and 8 which entail entering the standard and sample amounts into the chromatographic data software. In addition, step 10, which is the integration of the peaks, can be manipulated to inappropriately change the peak areas
Initially the reliability and trustworthiness of a set of analytical results can be confirmed by examining the consistency and integrity of each stage of the analytical process that produced the results. This can be done by confirming, from the date time stamps, that all the component events in the analytical process were performed in the expected sequence. Most of the component events create some documented evidence of the time it was performed.
In steps 1 and 2, if the preparation of HPLC mobile phase, and sample & standard solvent entails preparing a buffer of salt solution the balance and pH meter printouts will document the time of preparation. Of cause, it is not possible to measure the pH of a solution until after it has been prepared, therefore the time on the balance printout should precede that of the pH meter. In step 3, the time of standard solution preparation may be a key event in the analytical process, as these solutions may have limited stability. The preparation of the standard solutions will usually entail weighing of the standard reference material and the time the weighing was carried out can be determined from balance printouts.
In step 4, as with the preparation of the standard solutions, the system suitability solutions will usually entail weighing standard reference material and any other substances, which is also used to assess system suitability. Therefore, the date time stamp on the balance printout will establish the time of the weighing’s for the preparation of this solution.
In step 5, the saving of the HPLC method file will create a date time stamp; this should precede the collection of any chromatographic data, such as the system suitability check.
Running the system suitability check, in step 6, entails injecting and running sample solutions; this will create a date time stamp each time an injection is made. These should come after the preparation of all solutions required for this step and the time the HPLC method was saved.
The time of sample preparation, step 7, may be a key event in the analytical process, as sample solutions may have limited stability. Sample preparation normally entails weighing the sample, if only to provide evidence of the correct number of dose units were used in the preparation. The balance printout will establish the time the weighing’s were made, and sample solutions should be made up as soon as possible after the weighings are made.
Saving the sequence file, in step 8, will create a date time stamp; this should precede the start of the collection of sample chromatographic data. Raw and processed data files should be sequentially numbered starting at 1 and should have no gaps. Any gaps may be indicative of missing files.
During the HPLC analysis, step 9, a date time stamp will be created each time a sample is injected, corresponding to the time the raw data file was created. If an auto-
During the processing of the raw data files to integrate the chromatographic peaks, step 10, a date time stamp is created corresponding to the time the processed data file (which is sometimes called a result file) was created. This may either occur
during the post run processing prior to the next sample, or
after all the samples have been injected.
Whichever option is used by the software it should be consistent for every injection within the sequence, and the date time stamps should reflect this.
Following the creation of all the processed data (or result) files, the next step is to turn the raw peak areas into meaningful results which represents the amount of analyte in the sample. This is carried out during the calibration, calculation and reporting stage of the analytical process, steps 11 and 12. A further date time stamp is created at this point which corresponds to the creation of the report files. This will invariably occur only after all the result files have been created. The date time stamp on the report should become progressively later as the file number increases.
The chromatographic data software records each time a sequence is processed, generally the software will require a reason to be entered every time s sequenced is reprocessed. The number of times the sequence was reprocessed should be checked together with the reason entered each time the sequence was reprocessed. Multiple reprocessing of sequences without satisfactory explanation may be indicative of an attempt the manipulate the final result by manipulating the peak integration, and should be treated with suspicion. The reason for reprocessing a sequence should reflect the actual purpose for reprocessing. Words like update and reprocess are not sufficient.
10 Controlling Chromatographic Integration
High Performance Liquid Chromatography (HPLC) and Gas Chromatography (GC) are two of the most routinely used techniques in the modern analytical laboratory. The specificity, sensitivity and flexibility of the two techniques make them readily applicable to the determination of an enormous range of analytes in a wide range of sample matrices. The raw output from both techniques is a graph of signal strength verses time, usually called a chromatogram. This consists of a series of peaks which represent the component substances of a sample. The area of the peaks is usually proportional to the amount of the respective substance in the sample.
In order to quantitate the analytes in the sample it is necessary to determine the area of the peak; a process known as integration. Modern HPLC and GC instruments are invariably interfaced with computerised chromatographic data systems which are capable of performing the integration process automatically. The role of the analytical chemist is to select appropriate values for the parameters (such as: slope sensitivity, noise threshold, peak width, area threshold, and bunching factor and skim ratio) which are used by the processing software to define the respective chromatographic peaks.
As assigning the most appropriate chromatographic integration parameters requires a certain amount of judgement on the part of the analytical chemist, this presents the following issues from the quality assurance and data integrity perspective:
Assuring that the integration parameters are used, and therefore the peak integration itself is performed in a consistent way, and
Assuring that that the integration of peaks, (which when integrated and calibrated against a chromatogram of a standard solution of the respective analyte, may yield an out of specification result), is not manipulated in such a way as to give a result that conforms to specification. In other words, using the integration parameters to manipulate the peak area, in order to obtain a passing result from a peak that would otherwise produce a result that would fail to meet specifications. This is sometimes called integrating, or testing, in to compliance.
The proper integration of chromatographic peaks and the processes used to achieve accurate peak integration attracts significant scrutiny during regulatory audits, and the accreditation assessment process. Therefore, the assignment of integration parameters and the integration of chromatographic peaks will be controlled by a standard operating procedure (SOP) or similar document, and follow a scientifically sound process.
In particular, Changing the integration parameters until the integration looks good is unacceptable. Indeed, multiple re-
In addition, some authorities believe the same integration parameters should be used for each chromatographic run, once a method has been validated and is being used for the routine quality control operation. Indeed, some regulatory agencies advocate ‘securing’ chromatographic methods to assure the same integration parameters are always being used. We, however, does not advocate ‘locking’ methods to prevent changing parameters, as it does not allow atypical situations (such as extra peaks) to be readily addressed. We do, however, recommend including suitable chromatographic integration parameters in the approved written method, together with a picture of a typical acceptable chromatogram, and allowing the analytical chemist to make appropriate adjustments, should this be necessary in unusual circumstances. In these situations, it may be necessary to initiate an investigation, in order to determine the root cause of the unusual event.
It is therefore important that you establish appropriate policies and scientifically sound procedures that provide a high level of confidence that chromatograms are integrated in a consistent manner.
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