Yours Chromatographically, Kaushik Zala

As is known to us all, in the process of gas phase analysis, column is the “heart” of gas chromatograph, and it plays a crucial role in the qualitative and quantitative analysis of components. Recently, followers often consult about the aging of GC column. Today, we would like to share that with you.

Aging of GC column, in short, refers to the process of restoring column efficiency by baking the column at high temperature and taking the unstable stationary phase, possible impurities and pollutants out of the column by carrier gas.

What are the conditions that require aging treatment of the column?

1. Newly purchased column: For new column, prior to its initial use, the aging treatment can remove the stationary liquid that bonded unstably in the column or residual solvent in the packed column to ensure the stability of the properties of the new column.

2. For columns that have been left unused for a long time and need to be started again, the aging of the column can remove pollutants, oxygen and water caused by column being placed for a long time. And restore the properties of the column.

3. Columns that have been used for a long time or that have been through complex matrices and mass sample analysis: in this case, high boiling point impurities and pollutants remaining in the column can be mainly removed by aging; On the other hand, long-term use of column under high temperature will cause the loss of stationary liquid, exposing part of the active site. Through aging treatment, using the characteristics of thermal expansion and cold shrinkage of stationary phase, the active site on the inner wall of the column can be covered again. And restore the properties of the column.

How to operate, and what details do we need to pay attention to during the aging process?

1. Selection of aging temperature

In general, the aging temperature can be controlled between the maximum analytical temperature of the method and the upper limit of the constant temperature of the column.

The aging temperature can also be set to 20-30℃ lower than the upper limit of the column constant temperature; Or 20-30℃ higher than the maximum analysis temperature of the method.

It is important to note that each GC column has a temperature limit to which it can tolerate, and it is necessary to read the column box or instructions carefully before aging. In the aging process, once the column temperature limit is exceeded, it will lead to the loss of stationary phase and shorten the lifetime. Therefore, aging temperature can be lower as far as possible under the premise of ensuring the removal of impurities and pollutants.

2. Aging time

The specific aging process is generally set as program heating (slowly heating up to the set aging temperature), such as: the initial temperature is 35℃, 2-5℃/min, heating up to the aging temperature, and keeping 0.5-2h. The specific aging time can be determined according to the effect of impurity removal.

3. Prevent oxygen into the column

Because at high temperatures, with the presence of oxygen, the stationary liquid is easily oxidized, the stable silane bond will break, causing serious column loss and column efficiency declination.

Therefore, in order to avoid oxygen entering the column, the following points should be noted:

● Connect the gas inlet of the column to the injection port of the instrument. Place the end of the column in alcohol and take carrier gas to observe whether there are continuous bubbles. If not, check the column for mid-section fracture, installation, and leakage of the system.

● Set the carrier gas flow rate to the normal working value, the injection port, column oven and detector (if connected to the detector) to 35℃ or turned off the instrument temperature control system. The carrier gas is available for 15-30 minutes at room temperature to replace the oxygen that may exist in the instrument system and the column.

● Ensure that the other joints of the instrument are properly installed and pass leaking test.

4. Avoid pollution

In general, in order to avoid contamination of the detector, it is not recommended to connect the detector during the aging process. The normal operation is to use a solid pressure ring to plug the lower end of the detector and close the temperature. If the detector is connected, for the FID detector, there is no need to ignite, and air and hydrogen need not be turned on; If it is an ECD detector, tailing blowing should be set to avoid excessive heat and temperature which transfer to the ECD, so as to ensure the safety of the radioactive source inside the detector. In addition, it is prohibited to use hydrogen to age the column, that is to avoid hydrogen leakage and accumulation in the column temperature chamber, which will cause explosion.

5. Relevant maintenance shall be carried out before aging

For columns that have been used for a long time or that have through analysis of complex matrices and multiple samples, aging is to remove some of the residual contaminants. These contaminants tend to be compounds with higher boiling points which accumulate at the head of the column, such as proteins, pigments, gels, etc. in the sample. In order to avoid the pollutants to continue to transfer to the column while they can not be completely removed from the column inside the column, before aging column should be cut, appropriately cut off part of the column. In addition, it is necessary to maintain the injector liner, quartz cotton and the injector spacer to avoid secondary contamination of the column in the aging process. In conclusion, aging of column is meaningful after removing the source of pollution.

Aging Of Column

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Tag :// #GC

Peak Fronting Tailing peaks are almost ubiquitous in liquid chromatography (LC) separations. Over the past 20 years of "LC Troubleshooting," at least a dozen instalments of this feature have dealt with tailing peaks. In the days of lower-purity silica, peak tailing was often the result of strong acid-base interactions between basic sample functional groups, such as amines and acidic silanol groups on the silica surface. One popular way to combat such tailing was to add triethylamine to the mobile phase to saturate the stationary phase's acidic sites. With the widespread use of high-purity silica as the backbone of most of today's reversed-phase columns, tailing problems have been reduced to the extent that amine mobile phase additives are seldom used. Today, silanol tailing remains, but is much less of a problem. Another common cause of peak tailing, column overload, was discussed in last month's "LC Troubleshooting" instalment.¹ Peak fronting is much more rare than peak tailing. There is some speculation that complaints are low because peak fronting merely makes a badly tailing peak look more symmetric, but this is a viewpoint for cynics. In our laboratory, we rarely see fronting peaks, and this is likely the problem in most scientists' experience. One classic example of fronting in ion-pair chromatography showed that peak fronting could be eliminated with a change in the column temperature.² A previous "LC Troubleshooting" column discussed another case in which peak fronting might have been attributable to a void in the column or the mobile phase problems, but the cause of the problem was not definitive.³

A satisfactory chemical model for peak fronting in reversed-phase LC with most samples is difficult to postulate. However, a problem with the physical structure of the column is more reasonable. An asymmetric void at the head of the column, channelling within the column, or a less dense bed structure along the walls off the column than in the middle, each creates a model that allows one to visualize the fronting process. If a portion of the sample molecules travel through this less dense part of the column, they will travel more quickly, distorting the peak. If the bulk of the peak is retained in the normal fashion, a fronting peak will occur.

We recently observed a case of severe peak fronting that appears to fit the hypothesis of a column void or distortion in the column bed. The LC–tandem mass spectrometry (LC–MS–MS) method uses a 100 mm × 2.1 mm C18 column packed with 5 μm diameter particles designed to work well with 100% aqueous phases. Mobile phase A was 10 mM ammonium carbonate (pH 9.0), and mobile phase B was methanol. An isocratic mobile phase of 5% B was run for 5 min at a flow-rate of 0.5 mL/min, followed by an 80% methanol flush. Normally, the method produces chromatograms with symmetric peaks. After approximately 500 injections of extracted plasma samples, the chromatograms had deteriorated to the degree. Column reversal was ineffective and normal pressures were observed, suggesting that frit blockage was not the problem source. The column was replaced and the chromatogram was similar to initial. We have seen this failure pattern for several columns, indicating that a column lifetime of approximately 500 injections is typical for this method.

Column Life Expectancy Replacement of the column after 500 injections of the sample above might bring some gasps of horror from some readers. A question we hear frequently relates to how long a column should last. We have methods in our laboratory for which column lifetime of 2000 injections are common. Conversely, we've had users tell us of methods in which column failure is observed after 50 or fewer injections — and they are not upset.

Before going into techniques to extend column life, we should consider the cost of the column in the big scheme of things. We work in a contract research organization (CRO), so we make our living from running other people's samples. In the CRO world, LC sample analysis costs generally are $50/sample and up. For our earlier example, the column costs about $500; at 500 samples/column, this translates to $1/sample or 2% of the cost. If we could double the life of the column, we would only reduce the cost to 1%, hardly worth the trouble. However, with a $500 column, many people seem to treat the column as a capital item instead of a consumable. Contrast this with a method that uses solid-phase extraction (SPE) for sample clean-up. SPE cartridges or 96-well plates cost at least $2/sample. This is twice the cost of the analytical column, yet we think nothing of throwing the SPE cartridges away after a single use — they are sold as consumable items. Rather than trying to improve column life, a better investment for cost reduction is to figure out ways to reduce labour costs or improve throughput of expensive LC–MS–MS detectors by the use of techniques such as parallel chromatography.⁴

Extending Column Life Although this discussion should convince us that we do not want to spend too much time trying to extend column life, there are some simple techniques that will extend the useful life of a column. The most common mode of failure of columns today is excessive pressure resulting from build-up of particulate matter at the head of the column. Make sure that your samples are free of particulates. Filtration of each sample or centrifugation of samples to eliminate particles will go a long way towards this goal. Another inexpensive, but very effective tool is a 0.5 μm porosity in-line filter mounted just downstream from the autosampler. This will catch the particles that make it past your filtration or centrifugation efforts so that they do not block the column inlet frit. When the system pressure rises to an unacceptable level, simply replace the frit in the filter and you should be back in business. Many workers find that guard columns are beneficial to improving column life. These small columns upstream from the analytical column catch both particulate matter and strongly retained materials that might foul the column packing on the analytical column. If you use guard columns, be sure to discard them before the contaminants break through onto the main column. Also, when flushing the system with strong solvent, be sure to flush the guard column to waste, not onto the analytical column, or you might defeat the purpose of the guard column.

Sample clean-up is another technique to extend column usefulness. You need to remember that there is an economic balance in sample clean-up versus column costs. Does it make sense to spend $10/sample for clean-up to reduce the per-sample cost of the column's contribution from $2/sample to $1/sample? In our opinion, one major goal of sample clean-up should be to improve method ruggedness so that you are assured of collecting meaningful data from your samples. Some workers perform the absolute minimum of clean-up, expect their columns to do the clean-up work, and are satisfied if the column lasts for 100 samples. In other instances, extensive sample clean-up can lower the background noise and allow a 10-fold lower limit of quantification; longer column life is only a peripheral benefit. You have to work out the economics on a case-by-case basis.

Column Conditioning You might have noticed that some LC methods take a while before they "settle down" and give consistent results. For example, it may take five or six injections before the retention time, peak height or peak area stabilizes to a satisfactory level of variability. What is going on? Many workers think of a reversed-phase separation as simple partition-like separation between the mobile phase and a homogeneous stationary phase surface. Unfortunately, this is not the situation. The closer you look, the less homogeneous the stationary phase appears. In some instances, there are slow and fast equilibria going on at the same time. Sometimes the analyte molecules are retained by more than one mechanism. Loading sample onto the column might allow the slow-equilibrium mechanism to saturate so consistent results are seen. In other instances, it might be proteins, polymers or other analytically unimportant matrix materials that must be loaded onto the column before the method behaves well. Injection of several mock samples will usually suffice. We have several methods that include five to ten conditioning injections before injecting the standard curve. This is alright if the runtime is short, but if the method is a conventional LC–UV method, the runtime may be 20–30 min, so extensive conditioning might be unacceptable from a sample-throughput standpoint. Because the conditioning process is often related to the mass of sample (or matrix) loaded on the column, one might be able to shorten the conditioning cycle by making the conditioning injections one after the other without waiting for elution to occur. For example, if the method has a 20 min runtime, just start the method, and then make five injections at 30 s intervals rather than waiting for 20 min for each one. An alternative is to make a single large-mass injection. Try one or more of these techniques and see if it will help your method settle down quickly for normal operation.

References 1. John W. Dolan, LCGC Eur.,18(6), 318–322 (2005).

2. P.A. Asmus, J.B. Landis and C.L. Vila, J. Chromatogr. 264, 241 (1983).

3. C. Hawkins and J.W. Dolan, LCGC Eur., 17(1), 32–40 (2004).

4. M.D. Nelson and J.W. Dolan, LCGC Eur., 17(5), 272–277 (2004).

yours chormatographically,

kaushik zala

Peak Fronting - Overview on Traditional Trouble of Chromatographer

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1. Instrument performance
ICP-OES quantitation is based on measurement of excited atoms and ions at the wavelength characteristics for the specific elements being measured. ICP-MS, however, measures an atom’s mass by mass spectrometry (MS). Due to the difference in metal element detection, the lower detection limit for ICP-MS can extend to parts per trillion (ppt), where the lower limit for ICP-OES is parts per billion (ppb). Obviously, if the elements for detection have regulatory limits that are below or near the lower detection limit of ICP-OES, ICP-MS is the instrument of choice.

2. Characteristics of the environmental sample
ICP-OES is mainly used for samples with high total dissolved solids (TDS) or suspended solids and is, therefore, more robust for analyzing ground water, wastewater, soil, and solid waste. It can be used for drinking water analysis as well. But in general, ICP-OES is used to measure contaminants for environmental safety assessment and elements with a higher regulatory limit. ICP-MS, on the other hand, is especially useful for analyzing samples with low regulatory limits. In addition, ICP-OES has much higher tolerance for TDS (up to 30%). ICP-MS has much lower tolerance for TDS (about 0.2%) although there are ways to increase the tolerance. Although both ICP-OES and ICP-MS can be used for high matrix samples, sample dilution is often necessary for use on ICP-MS. In addition, if a sample contains analytes of great difference in concentration, ICP-MS has wider dynamic linear range so the sample may not be diluted to detect these elements at the same time.

3. Regulatory requirements
In the U.S., the regulatory compliance monitoring for ICP-OES is governed by EPA Methods 200.5 and 200.7. EPA Method 200.7 was approved for use as axial view of ICP-OES and is therefore the EPA method for compliance monitoring by ICP-OES. EPA Method 200.8 governs regulatory compliance using ICP-MS. Both EPA 200.7 and 200.8 can be used for compliance of the Safe Drinking Water Act (SDWA) and the Clean Water Act (CWA).
For drinking water regulatory compliance or SDWA compliance, either ICP-OES or ICP-MS alone is not sufficient. Regulatory compliance can be accomplished by the combination of ICP-OES (for minerals) and ICP-MS, or ICP-OES and GFAA (using EPA 200.9), or ICP-MS and GFAA (for minerals). ICP-OES cannot be used to measure arsenic, mercury, and some other toxic metals with very low regulatory limits using EPA Method 200.7. ICP-MS can’t be used to measure the minerals (Na, K, Ca, Mg, and Fe) in drinking water using EPA Method 200.8. It is also important to mention that current EPA Method 200.8 version 5.4 cannot use collision cell technology for drinking water analysis, reducing the power to use ICP-MS to minimize polyatomic interferences.

Comparison of ICP-MS and ICP-OES Advantages and Methods

ICP-MS

Main advantages

ICP-MS is becoming a workhorse for metal analysis in water not only because it offers lower detection limit. The following features also contribute its wide range of environmental applications:

· Wide dynamic range

· Efficiently remove polyatomic spectral interferences using collision cell technology

· Rapid semi-quantitative analysis

· Isotopic analysis

· Speciation capability

Regulatory methods

· EPA 200.8

· EPA 321.8 (IC-ICP-MS)

· EPA 6020

· ISO/DIS 17294-1:2004

· ISO 17294-2:2016

· NEN 6427:1999

ICP-OES

Main advantages

ICP-OES is used for all the matrices of environmental samples especially for high-matrix samples. The following features also contribute its wide range of environmental applications:

· Only analytical grade reagents are sufficient

· Simpler method development does not need a specialist with highly technical expertise

· Overall is a cheaper option if the elements do not need lower detection limit that ICP-MS delivers

Regulatory methods

· ISO/TC 190/SC3/WG1 N0252

· NPR 6425:1995

· NEN 6426:1995

· EN 12506: 2003

Yours Chromatographically
Kaushik Zala

Ref., https://www.thermofisher.com/in/en/home/industrial/environmental/environmental-learning-center/contaminant-analysis-information/metal-analysis/comparison-icp-oes-icp-ms-trace-element-analysis.html

Comparison of ICP-OES and ICP-MS for Trace Element Analysis

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Separation science is always looking for new and effective strategies to accomplish the tasks of modern analytics. Especially for polar compounds reversed phase HPLC – the most common analytical method – is often limited. Here, hydrophilic stationary phases provide an additional tool for the separation of polar analytes in HPLC.
The expression HILIC (Hydrophilic Interaction Chromatography) was firstly published by Andrew Alpert in 1990 – since then it took quite some efforts to develop robust and reproducible hydrophilic HPLC phases for HILIC chromatography [A. Alpert, J. Chromatography 499 (1990), 177–196].

HILIC combines the characteristics of the 3 major methods in liquid chromatography – reversed phase (RPC), normal phase (NPC) and ion chromatography (IC):

Stationary phases (adsorbents) are mostly polar modifications of silica or polymers (SiOH, Amino, Diol, (zwitter) ions, …) – like in NPC.

Mobile phases (eluents) are mixtures of aqueous buffer systems and organic modifiers like acetonitrile or methanol – like in RPC.

Fields of application include quite polar compounds as well as organic and inorganic ions – like in IC.

HILIC is NP chromatography of polar and ionic compounds under RP conditions.”

Retention characteristics
Commonly HILIC is described as partition chromatography or liquid/liquid extraction system between the mobile and stationary phase. Versus a water-poor layer of mobile phase a water-rich layer on the surface of the polar stationary phase is formed. Thus, a distribution of the analytes between these two layers will occur. Furthermore HILIC includes weak electrostatic mechanisms as well as hydrogen donor interactions between neutral polar molecules under high organic elution conditions. This distinguishes HILIC from ion exchange chromatography - main principle for HILIC separation is based on compound’s polarity and degree of solvation. More polar compounds will have stronger interaction with the stationary aqueous layer than less polar compounds – resulting in a stronger retention. Nonpolar compounds exhibit faster elution profiles due to minor hydrophobic interactions. Thus, as shown for the separation of uracil and naphthalene the elution order is quite often inverse on HILIC columns compared to RP columns.

HILIC seperations

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INTRODUCTION

Testing to the specification of an ancillary material, intermediate, and/or ingredient and product is critical in establishing the quality of a finished dosage form. The transfer of analytical procedures (TAP), also referred to as method transfer, is the documented process that qualifies a laboratory (the receiving unit) to use an analytical test procedure that originated in another laboratory (the transferring unit), thus ensuring that the receiving unit has the procedural knowledge and ability to perform the transferred analytical procedure as intended. The purpose of this general information chapter is to summarize the types of transfers that may occur, including the possibility of waiver of any transfer, and to outline the potential components of a transfer protocol. The chapter does not provide statistical methods and does not encompass the transfer of microbiological or biological procedures.

TYPES OF TRANSFERS OF ANALYTICAL PROCEDURES

TAP can be performed and demonstrated by several approaches. The most common is comparative testing performed on homogeneous lots of the target material from standard production batches or samples intentionally prepared for the test (e.g., by spiking relevant accurate amounts of known impurities into samples). Other approaches include covalidation between laboratories, the complete or partial validation of the analytical procedures by the receiving unit, and the transfer waiver, which is an appropriately justified omission of the transfer process. The tests that will be transferred, the extent of the transfer activities, and the implementation strategy should be based on a risk analysis that considers the previous experience and knowledge of the receiving unit, the complexity and specifications of the product, and the procedure.

Comparative Testing

Comparative testing requires the analysis of a predetermined number of samples of the same lot by both the sending and the receiving units. Other approaches may be valid, e.g., if the receiving unit meets a predetermined acceptance criterion for the recovery of an impurity in a spiked product. Such analysis is based on a preapproved transfer protocol that stipulates the details of the procedure, the samples that will be used, and the predetermined acceptance criteria, including acceptable variability. Meeting the predetermined acceptance criteria is necessary to assure that the receiving unit is qualified to run the procedure.

Covalidation Between Two or More Laboratories

The laboratory that performs the validation of an analytical procedure is qualified to run the procedure. The transferring unit can involve the receiving unit in an interlaboratory covalidation, including them as a part of the validation team at the transferring unit and thereby obtaining data for the assessment of reproducibility. This assessment is made using a preapproved transfer or validation protocol that provides the details of the procedure, the samples to be used, and the predetermined acceptance criteria. The general chapter Validation of Compendial Procedures (1225) provides useful guidance about which characteristics are appropriate for testing.

Revalidation

Revalidation or partial revalidation is another acceptable approach for transfer of a validated procedure. Those characteristics described in (1225) ,which are anticipated to be affected by the transfer, should be addressed.

Transfer Waiver

The conventional TAP may be omitted under certain circumstances. In such instances, the receiving unit is considered to be qualified to use the analytical test procedures without comparison and generation of interlaboratory comparative data. The following examples give some scenarios that may justify the waiver of TAP.

• The new product’s composition is comparable to that of an existing product and/or the concentration of active ingredient is similar to that of an existing product and is analyzed by procedures with which the receiving unit already has experience.

• The analytical procedure being transferred is described in the USP–NF, and is unchanged. Verifiction should apply in this case (see 1226).

• The analytical procedure transferred is the same as or very similar to a procedure already in use.

The personnel in charge of the development, validation, or routine analysis of the product at the transferring unit are moved to the receiving unit. If eligible for transfer waiver, the receiving receiving unit should document it with appropriate justifications.

ELEMENTS RECOMMENDED FOR THE TRANSFER OF ANAYTICAL PROCEDURES

Several elements, many of which may be interrelated, are recommended for a successful TAP. When appropriate and as a part of pretransfer activities, the transferring unit should provide training to the receiving unit, or the receiving unit should run the procedures and identify any issues that may need to be resolved before the transfer protocol is signed. Training should be documented. The transferring unit, often the development unit, is responsible for providing the analytical procedure, the reference standards, the validation reports, and any necessary documents, as well as for providing the necessary training and assistance to the receiving unit as needed during the transfer. The receiving unit may be a quality control unit, another intracompany facility, or another company such as a contract research organization. The receiving unit provides qualified staff or properly trains the staff before the transfer, ensures that the facilities and instrumentation are properly calibrated and qualified as needed, and verifies that the laboratory systems are in compliance with applicable regulations and in-house general laboratory procedures. Both the transferring and receiving units should compare and discuss data as well as any deviations from the protocol. This discussion addresses any necessary corrections or updates to the final report and the analytical procedure as necessary to reproduce the procedure. A single lot of the article may be used for the transfer, because the aim of the transfer is not related to the manufacturing process but rather to the evaluation of the analytical procedure’s performance at the receiving site.

PREAPPROVED PROTOCOL

A well-designed protocol should be discussed, agreed upon, and documented before the implementation of TAP. The document expresses a consensus between the parties, indicating an intended execution strategy, and should include each party’s requirements and responsibilities. It is recommended that the protocol contain the following topics as appropriate: objective, scope, responsibilities of the transferring and receiving units, materials and instruments that will be used, analytical procedure, experimental design, and acceptance criteria for all tests and/or methods included in the transfer. Based on the validation data and procedural knowledge, the transfer protocol should identify the specific analytical performance characteristics (see 1225 and 1226) that will be evaluated and the analysis that will be used to evaluate acceptable outcomes of the transfer exercise. The transfer acceptance criteria, which are based on method performance and historical data from stability and release results, if available, should include the comparability criteria for results from all study sites. These criteria may be derived using statistical principles based on the difference between mean values and established ranges and should be accompanied by an estimation of the variability (e.g., percent relative standard deviation [%RSD] for each site), particularly for the intermediate precision %RSD of the receiving unit and/or a statistical method for the comparison of the means for assay and content uniformity tests. In instances of impurity testing, where precision may be poorer such as in the case of trace impurities, a simple descriptive approach can be used. Dissolution can be evaluated by a comparison of the dissolution profiles using the similarity factor f2 or by comparison of data at the specified time points. The laboratories should provide appropriate rationale for any analytical performance characteristic not included. The materials, reference standards, samples, instruments, and instrumental parameters that will be used should be described. It is recommended that expired, aged, or spiked samples be carefully chosen and evaluated to identify potential problems related to differences in sample preparation equipment and to evaluate the impact of potential aberrant results on marketed products. The documentation section of the transfer protocol may include report forms to ensure consistent recording of results and to improve consistency between laboratories. This section should contain the additional information that will be included with the results, such as example chromatograms and spectra, along with additional information in case of a deviation. The protocol should also explain how any deviation from the acceptance criteria will be managed. Any changes to the transfer protocol following failure of an acceptance criterion must be approved before collection of additional data.

THE ANALYTICAL PROCEDURE

The procedure should be written with sufficient detail and explicit instructions, so that a trained analyst can perform it without difficulty. A pretransfer meeting between the transferring and receiving units is helpful to clarify any issues and answer any questions regarding the transfer process. If complete or partial validation data exist, they should be available to the receiving unit, along with any technical details required to perform the test in question. In some cases it may be useful for the individuals who were involved with the initial development or validation to be on site during the transfer. The number of replicates and injection sequences in the case of liquid or gas chromatography should be clearly expressed, and, in the case of dissolution testing, the number of individual dosage units should be stipulated.

TRANSFER REPORT

When the TAP is successfully completed, the receiving unit should prepare a transfer report that describes the results obtained in relation to the acceptance criteria, along with conclusions that confirm that the receiving unit is now qualified to run the procedure. Any deviations should be thoroughly documented and justified. If the acceptance criteria are met, the TAP is successful and the receiving unit is qualified to run the procedure. Otherwise, the procedure cannot be considered transferred until effective remedial steps are adopted in order to meet the acceptance criteria. An investigation may provide guidance about the nature and extent of the remedial steps, which may vary from further training and clarification to more complex approaches, depending on the particular procedure.

Yours Chromatographically

#KZ

TRANSFER OF ANALYTICAL PROCEDURES USP 1224

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Hydrophilic interaction chromatography (or hydrophilic interaction liquid chromatography, HILIC) is a variant of normal phase liquid chromatography that partly overlaps with other chromatographic applications such as ion chromatography and reversed phase liquid chromatography. HILIC uses hydrophilic stationary phases with reversed-phase type eluents. The name was suggested by Dr. Andrew Alpert in his 1990 paper on the subject.^[1] He described the chromatographic mechanism for it as liquid-liquid partition chromatography where analytes elute in order of increasing polarity, a conclusion supported by a review and re-evaluation of published data.^[2]