HPLC Method Validation

Following establishment of selectivity, the FIPLC method should be validated. The validation of an analytical method is meant to demonstrate the suitability of the method to perform its intended purpose. Validation is an important 

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HPLC methods can usually be transferred without many modifications, since most commercially available HPLC instruments behave similarly. This is certainly true when the columns applied have a similar selectivity. One adaptation, sometimes needed, concerns the gradient profiles, because of different instrumental or pump dead-volumes. However, larger differences exist between CE instruments, e.g., in hydrodynamic injection procedures, in minimum capillary lengths, in capillary distances to the detector, in cooling mechanisms, and in the injected sample volumes. This makes CE method transfers more difficult. Since robustness tests are performed to avoid transfer problems, these tests seem even more important for CE method validation, than for HPLC method validation. However, in the literature, a robustness test only rarely is included in the validation process of a CE method, and usually only linearity, precision, accuracy, specificity, range, and/or limits of detection and quantification are evaluated. Robustness tests are described in references 20 and 59-92. Given the instrumental transfer problems for CE methods, a robustness test guaranteeing to some extent a successful transfer should include besides the instrument on which the method was developed at least one alternative instrument. 

Pluym et al. compared the use of CE to that of HPLC in chemical and pharmaceutical quality control. They stated that CE could be considered as a complementary technique to HPLC because of its large separation capacity, its simplicity, and its economical benefits. Jimidar et al. decided that CE offers high separation efficiency and can be applied as an adjunct in HPLC method validation. Mol et al. evaluated the use of micellar electrokinetic chromatography (MEKC) coupled with electrospray ionization mass spectrometry (ESI—MS) in impurity profiling of drugs, which resulted in efficient separations. 

J.A. Van Leeuwen, L.M.C. Buydens, B.G.M. Vandeginste, G. Kateman, P.J. Schoenmakers, M. Mulholland, RES, an expert system for the set-up and interpretation of a ruggedness test in HPLC method validation. Part 1 The ruggedness test in HPLC method validatioa Chemometrics and Intelligent Laboratory systems, 10 (1991) 337-347. 

Molgaard P, Ohnsen S, Christensen P, Cornett C. HPLC method validation for simultaneous analysis of cichoric acid and alkamides in Echinacea purpurea plants and products. J Agric Food Chem 2003 51 6922-6933. 

During HPLC method validation, it is imperative to test the finished optimized method on several (usually three) new columns from different production batches in order to see whether the separation still functions. If this is the case, you can be hopeful that future batches will work. Sometimes, it is necessary, however, to precondition the columns by means of a defined conditioning program before they meet the requirements of the separation. This is the reason why the verification of the selectivity is so important. 

The specification development process is a data-driven activity that requires a validated analytical method. The levels of data needed include assay precision, replicate process results (process precision), and real-time stability profiles. A statistical analysis of these data is critical in setting a realistic specification. Most often, aggregation and fragmentation degradation mechanisms are common to protein and peptide therapeutics. Therefore, the SE-HPLC method provides a critical quality parameter that would need to be controlled by a specification limit. 

Chandra, A., Rana, J., and Li, Y., Separation, identification, quantification, and method validation of anthocyanins in botanical supplement raw materials by HPLC and HPLC-MS, J. Agric. Food Chem., 49, 3515, 2001. 

In 1994, only 15% of EPA method validations (tolerance method validation and environmental chemistry method validations) that involved GC were carried out using GC/MS. In 2002, this number is reversed in that 85% of the GC methods that were validated by both programs used GC/MS. Many of the compounds investigated in these method trials were polar compounds, and hence these compounds required derivatization in order to be amenable to GC. One common methylating agent is (trimethylsilyl)diazomethane, which is used, for example, to methylate the sulfonamide flumetsulam. As opposed to HPLC/MS, where derivatization is often not necessary, the GC/MS procedure involves an extra step to methylate this compound, under dry conditions, prior to determination by GC/MS. 

Full acceptance of HPLC/MS methods by the US EPA OPP as enforcement methods occurred between 1998 and 2001. For example, in 1998, the EPA OPP accepted HPLC/MS (without MS/MS) methods as primary enforcement methods, and high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) only was suitable for confirmatory methods. However, in 2001, HPLC/MS/MS methods also became acceptable for primary enforcement. Table 4 summarizes the types of methods that were validated by the EPA OPP method validation program, for both food tolerance enforcement methods and environmental chemistry methods. 

The final step of method development is validation of the HPLC method. Optimisation of chromatographic selectivity [110], performance verification testing of HPLC equipment [591], validation of computerised LC systems [592] and validation of analysis results using HPLC-PDA [34] were reported. The feasibility of automated validation of HPLC methods has been demonstrated [593]. Interlaboratory transfer of HPLC methods has been described [594]. 

In most situations analysts can achieve a rapid reasonable separation of compounds using an appropriate standard CE method with generic operating conditions [877]. This eliminates or reduces dramatically the need for method development. Major instrumental error sources in CE are detection, integration and injection. General guidelines for validation of CE methods are available and similar to those of HPLC [878]. Validated CE methods often perform the same as, or better than, the corresponding HPLC methods. 

The pH-metric procedure has been validated against the standard shake-flask method [150,357], and many studies using it have been reported [56,149-151,153,161,162,224,225,229,246,250,268,269,275,276,280,281,324-363], Determinations of values of log P as low as —2 and as high as +8 have been documented [161,162,352]. The published literature clearly indicates that the Dyrssen technique is a reliable, versatile, dynamic, and accurate method for measuring logP. It may lack the speed of HPLC methods, and it cannot go as low in log P as the CV... 

In ocular applications, Raman spectroscopy can quickly and objectively assess composite lutein and zeaxanthin concentrations of macular pigment using spatially averaged, integral measurements or images that quantify and map the complete MP distribution with high spatial resolution. Importantly, both variants can be validated with HPLC methods in excised human eyecups and in animal models. 

G.C.H. Derksen, G.P. Lelyveld, T.A. van Beek, A. Capelle and JE. Groot, Two validated HPLC methods for the quantification of alizarin and other anthraquinones in Rubia tinctorum cultivars, Phytochem. Anal., 15, 397 406 (2004). 

The near-IR technique has been used very successfully for moisture determination, whole tablet assay, and blending validation [23]. These methods are typically easy to develop and validate, and far easier to run than more traditional assay methods. Using the overtone and combination bands of water, it was possible to develop near-IR methods whose accuracy was equivalent to that obtained using Karl-Fischer titration. The distinction among tablets of differing potencies could be performed very easily and, unlike HPLC methods, did not require destruction of the analyte materials to obtain a result. 

Fogli et al. developed and validated an HPLC method with fluorescence detection for simultaneous routine TDM of anthracyclines and their metabolites.27 They coupled a Waters LC Module I Plus system equipped with a WISP 416 autosampler with a Model 474 scanning fluorescence spectrophotometer. The stationary phase was a Supelcosil LC-CN column (250 x 4.6 mm, 5 /um particle size) with a /iBondapak-CN guard column. The mobile phase consisted of 50mM monobasic sodium phosphate buffer and acetonitrile (65 35 v/v), adjusted to pH 4.0 with phosphoric acid. The flow rate was 1 mL/min. The fluorescence detection was set at excitation wavelengths of 233, 254, and 480 nm and at an emission wavelength of 560 nm. 

Because of the good validation parameters, the RP-HPLC method combined with SPE has been proposed for the investigation of the pharmacokinetics of RCA in plasma and brain [108],... 

Moorehouse K.G., Nashabeh W., Deveney J., Bjork N.S., Mulkerrin M.G., and Ryskamp T. (1997), Validation of an HPLC method for the analysis of the charge heterogeneity of the recombinant monoclonal antibody IDEC-C2B8 after papain digestion, J. Pharm. Biomed. Anal. 16, 593-603. 

Method validation is discussed in Chapter 7 as it relates to the HPLC methods of analysis. Validation is a process required by law, and the concept is described by regulatory agencies in the guidance documents. The analyst performing method validation is responsible for interpreting the... 

A PDA detector provides UV spectra of eluting peaks in addition to monitoring the absorbance of the HPLC eluent like the UVA is absorbance detector. It is the preferred detector for testing impurities and for method development. PDA facilitates peak identification during methods development and peak purity evaluation during method validation. Detector sensitivity was an issue in earlier models but has improved significantly (more than ten-fold) in recent years. ... 

Final methods are developed for transfer to operational quality control (QC) laboratories for the release testing of production batches. Additionally, the methods are intended to be applied during Registration Stability studies and for the release of the DP or DS validation batches during the pre-approval development stage. The analytical methods should last for the entire product lifetime therefore, the aim of final method development is to generate fast, robust, reliable, and transferable HPLC methods (preferably isocratic and at low cost). 

Validation is the process of collecting documented evidence that the method performs according to the intended purpose. " The validation characteristics and the acceptance criteria to be applied in validation of HPLC methods for MAA/NDA filings and marketed products should comply with the international guidelines on method validation. Table 11 details validation activities to be conducted for type 1, type 2, and type 3 methods ... 

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