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     SEPARATION SCIENCE LATEST EDITION 
     
    Transferring HPLC Compendial Methods to UHPLC for Routine Generic Drug Analysis
    Manufacturers of generic drugs must be able to prove that the products they produce are comparable to the brand-name drug. While the analytical methodologies used to characterize many drugs can be both difficult and costly to develop, generic drug producers can refer to the United States Pharmacopeia-National Formulary (USP-NF), as well as the British, European, and Japanese Pharmacopeias for information on how to analyze drug substance, drug product and associated excipients using analytical techniques such as high performance liquid chromatography (HPLC). 
     
    Implementing Robustness Testing for HPLC Methods
    This article is the first in a series about a practical approach to the implementation of robustness testing for HPLC analytical methods. In this first article the concept of robustness is introduced and an overview of the procedure for investigation of robustness is described. In subsequent articles practical advice will be provided on how to perform robustness testing following the described procedure. 
    Determination of Risperidone and 9-hydroxyrisperidone in Human Plasma
    A highly sensitive, selective, accurate and precise method for simultaneous quantification of risperidone and 9-hydroxyrisperidone in human plasma was developed. The method was based on electrospray ion trap tandem mass spectrometry in multiple reaction monitoring mode. Risperidone, 9-hydroxyrisperidone and carbamazepine, an internal standard, were extracted from plasma by a single step extraction with ether after the addition of sodium hydroxide and sodium chloride. A 5-μL aliquot of the sample reconstituted in mobile phase was analysed on a C18 column at 30 ˚C with the mobile phase consisting of acetonitrile and ammonium acetate buffer pH 5.5 (35:65 v/v).
     
     
    How to get more analysis out of your GC system?
    A common question we get asked by our customers is how they can get a longer column lifetime. This can be from a cost perspective (column price) or from a maintenance perspective (downtime, labour, calibration).
      

     HPLC SOLUTIONS LATEST EDITIONS 
     
    Gradient Distortion
    In the last installment of HPLC Solutions (#86) we looked at a simple technique to measure the dwell volume of an HPLC system. In a prior discussion (#85), it was seen that differences in dwell volume between two HPLC systems could result in offset retention times as well as possible changes in resolution for early-eluted peaks. Another potential problem can be diagnosed using the same dwell volume test, as is discussed below. 
     
     
    Measuring Dwell Volume
    In the last issue of HPLC Solutions (#85) we saw an example of how the appearance of a chromatogram could change when a gradient method was run on two HPLC systems of differing dwell volume. This week we’ll look at a simple way to measure dwell volume.
      

     GC SOLUTIONS LATEST EDITIONS 


    Inlet Activity 
    Many of the weaknesses inherent in gas chromatography are related to problems with the transport of sample into and through the inlet. Of these problems, sample loss (the inverse of recovery) and chemical changes (e.g., decomposition) are related to inlet activity, and much of that is dominated by the inlet liner. 
     
     
    Calibration Curves – Part 2
    This month we cover the internal standard method of GC calibration.The goal of any quantitative analysis is to accurately determine the concentration of target analytes in an original sample. Often, the original sample is not suitable for direct injection into a GC. Some of the reasons samples might need to undergo sample preparation prior to analysis are. Mattew Klee explains more...
      

     MS SOLUTIONS LATEST EDITIONS 

    Determination of Intact Protein Molecular Mass
    From Multiple-Charge Electrospray Mass Spectra 
    In two previous instalments of MS Solutions, I discussed the 
    sequencing of simple, single-charge peptide ions using 
    MS/MS. In this and another upcoming edition I am going to discuss 
    the use of multiple-charge ions in protein and peptide analysis.
     

    NIST 11: What’s New and What Value Does it Offer? Part 5
    This is the last in the five-part series about the features of NIST 11. This installment shows how spectra obtained by MS/MS methods from various soft ionization techniques, including those used with LC/MS can be searched against the NIST/EPA/NIH EI Mass Spectral Database and the results used to facilitate a structure determination.


     HPTLC SOLUTIONS LATEST EDITION 
     
    Parameters of the HPTLC Process
    An inherent advantage of planar chromatography is its enormous flexibility derived from the off-line principle and interaction of many parameters. It is helpful to know these parameters for each step of the process and to understand how they can affect the overall result in order to utilize the advantages for unlocking the full potential of high performance thin-layer chromatography (HPTLC). This issue of HPTLC Solutions is dedicated to the first part of the HPTLC process which includes plate handling, sample application, and chromatogram development. Read on for more information...


    HPTLC Today
    What is High Performance TLC and how can you benefit from it?
    In contrast to column chromatography (e.g., GC, HPLC), planar chromatography utilizes a flat (planar) stationary phase for separation. In thin-layer chromatography (TLC) this stationary phase is supported by a glass plate or a foil (plastic or aluminium). The TLC plate constitutes an open system, which during analysis passes through the individual steps (sample application, chromatogram development, detection, etc.) in an off-line mode. In this process many samples can be analysed in parallel on the same plate. The possibilities for adjusting and combining numerous parameters in order to optimize the separation create a flexibility that is unsurpassed by any other chromatographic technique.
     
     
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