Permethrin Drug Impurity Analysis with GC-MS with Cold EI and the Road to Failure in Such Analysis by GC-MS with Standard EI

Aviv Amirav, Tel Aviv University and Aviv Analytical

Abstract

A Permethrin impurity was successfully analyzed by GC-MS with Cold EI after it failed to be analyzed by GC-MS with standard EI. In this application note we demonstrate and discuss the ways GC-MS with standard EI analysis of relatively large compounds gradually becomes more difficult as the sample compound size is increased due to reduced total ion count signal, reduced molecular ion relative abundance and increased noise. Accordingly, as the analyzed sample compound becomes larger its GC-MS analysis becomes harder in a gradual fashion until it fails. In contrast, GC-MS with Cold EI can analyze twice larger compounds and thus significantly extends the range of compounds amenable for GC-MS analysis.    

Lipids in Human Serum Analysis by the 5975-SMB GC-MS with Cold EI

Aviv Amirav and Svetlana Tsizin, Tel Aviv University and Aviv Analytical, Tel Aviv Israel. 

Gabi Shefer, Ichilov hospital Tel Aviv Israel 

Introduction 

Cholesterol and triglycerides analysis in human blood is among the most widely used chemical medical diagnostics tests. Some estimate the number of such analysis at 1 Billion/year with cost of about $30 for each analysis (three analyses of cholesterol LDL, HDL and triglycerides at $10 each). Thus, the total lipids in blood analysis market is about $30 Billion/year. However, current analysis brings limited information and mass spectrometry can provide far better and more detailed lipids in blood information if an appropriate instrument for such analysis will be available. We used our GC-MS with Cold EI and demonstrated as below the analysis of large range of lipids in blood. Each analysis provided information on the amount of several free fatty acids, cholestadiene, cholesterol, vitamins E and 25 Hydroxy vitamin D3 and many diglycerides, cholesteryl esters and triglycerides. Notably, we can clearly distinguish differences among samples from different people. Each analysis took only 10 min via the use of column flow programing. Our results yielded extensive lipidomics information that may include new diagnostic tools. We feel that this new and advantageous assay for lipids profiling in blood is worthy of further investigation and evaluation.  

Impurities Analysis in Active Pharmaceutical Ingredients Comparison of Cold EI with Standard EI

Aviv Amirav, Tel Aviv University and Aviv Analytical, Tel Aviv Israel.

Introduction

Active pharmaceutical ingredients (APIs) in drug formulations need to have impurity levels < 0.1% according to the FDA or else the impurities need to be characterized via lengthy and expensive clinical toxicology procedures. Current impurities in APIs are typically analyzed by LC-MS. However, such LC-MS analysis is confronted by ion suppression effects for impurities that elute near the API, non-polar impurities are not ionized, those impurities that are discovered exhibit mostly protonated molecular ions without structural information and since Electrospray LC-MS has highly non-uniform ionization yields there is no information on the concentration of the discovered impurities. Thus, those API impurities that are observed need to be fully identified, synthesized and follow compound specific concentration calibration.

GC-MS with Cold EI is ideal for analysis of API impurities because:

• It has uniform compound independent response, thus detected impurity concentrations can be assessed, and those below 0.1% can be neglected 
• It often provides EI-based library identification, which is usually improved by the presence of an enhanced molecular in Cold EI plus structural information from the full display of fragment ions 
• Cold EI ionizes non-polar as well as polar analytes 
• It does not suffer from any ion suppression effects 
• Total ion mass chromatograms in Cold EI often provides greater sensitivity than ESI-LC-MS 
• Cold EI has much greater range of compounds amenable for analysis than any other GC-MS. 

Thus, Cold EI seems ideal for API impurities analysis.

Does this Pill Contain its Claimed Active Ingredients? Finasteride in Male Baldness Treatment Pills

Aviv Amirav, Professor of Chemistry at Tel Aviv University and Director - Aviv Analytical

Introduction

Finasteride (C23H36N2O2, MW = 372.2777, structure at right) is an approved drug for the treatment of male baldness. It acts as an inhibitor of the enzyme that converts testosterone to dehydrotestosterone. Finasteride pills are available by Merck and other companies but at a high price. They are also available from a relatively unknown Indian company at over three times lower price. Thus, a colleague friend approached us with a request to analyze a Finasteride pill from the Indian company to ensure the presence (or absence) of this active pharmaceutical ingredient and determine if it is a major or minor constituent in their pills. In fact, the topic of fake drugs is serious and requires attention thus we bring our advanced GC-MS experience with it into this post.

Keep reading how the 5975-SMB GC-MS with Cold EI enables Finasteride in male baldness treatment pills.
          

Drug Impurities Analysis by the Aviv Analytical 5975-SMB GC-MS with Cold EI

Aviv Amirav, School of Chemistry, Tel Aviv University and Director – Aviv Analytical 

Drugs are typically analyzed by LC-MS. When active pharmaceutical ingredients (API) are analyzed for the presence of impurities, the general requirements are that every impurity found should be at concentration below 0.1% of the API or it must be either cleaned or identified and toxicologically characterized which is a time consuming and expensive procedure. However, the ionization yields of Electrospray and/or APCI in LC-MS are highly non-uniform and compound dependent, and as a result when an impurity is found in a given LC-MS mass chromatogram its actual concentration is not known. Consequently, regardless of its actual concentration that can be well below 0.1% every impurity that is found must be isolated, fully identified, synthesized (or obtained) and serve for the provision of a calibration curve in order to measure the actual concentration of that small impurity peak. In addition, several types of impurities such as non-polar compounds are not properly ionized and are not detected by LC-MS. Thus, clearly drug impurity analysis represents an unmet analytical challenge.  

Alternatively, GC-MS with its standard electron ionization (EI) can be used and has, for volatile compounds, approximately uniform, semi-quantitative ionization yield. However, GC-MS with standard EI is compatible only with a limited range of thermally stable drugs and it provides useful molecular ions only for a portion of the analyzed compounds. Furthermore, ion source degradation and peak tailing severely erode the standard EI response uniformity for semi-volatile compounds. 

We used the Aviv Analytical 5975-SMB GC-MS with Cold EI for the analysis of drug impurities. Cold EI is the electron ionization of cold molecules in supersonic molecular beams (SMB). The technology of GC-MS with Cold EI is reviewed by A. Amirav, A. Gordin, M. Poliak, and A. B. Fialkov, J. Mass Spectrom., 43, 141-163. (2008). The later is available upon request. 

GC-MS with Cold EI as implemented with the Aviv Analytical 5975-SMB uniquely extends the range of drugs that are amenable for GC-MS analysis, including thermally labile drugs that are not compatible with standard GC-MS analysis. Furthermore, it is characterized by having uniform response to all compounds due to its contact-free fly-through ion source that eliminates any ion source peak tailing or losses. In addition, it provides trustworthy enhanced molecular ions that can be converted with the Tal-Aviv Molecule Identifier software into elemental formulae. Thus, the high sensitivity and uniform response of Cold EI uniquely enables the detection, identification and quantitation of low level impurities in drugs without lengthy calibration procedures. 

In order to evaluated the above attributes of the 5975-SMB we analyzed impurities in two Active Pharmaceutical Ingredient (API) samples (powder form) of Haloperidol and Ramelteon (Structures are given below).   

      

 

Keep reading to find our how the Aviv Analytical 5975-SMB GC-MS with Cold EI uniquely enables quantitative drug impurities analysis and helps in their identification. 

AM2201 Synthetic Cannabis Analysis using the 5975-SMB GC-MS with Cold EI

Aviv Amirav, Professor of Chemistry at Tel Aviv University and Director – Aviv Analytical

Introduction 

Synthetic cannabis is a family of psychoactive designer drugs derived of natural herbs sprayed with synthetic chemicals that, when consumed, allegedly mimic the pleasurable effects of cannabis. Synthetic cannabis is best known by the brand names such as K2 and Spice, both of which have largely become generic trademarks referring to any synthetic cannabis product. As the "herbal highs" market continues to boom, added synthetic cannabinoids are frequently exchanged to stay at least one step ahead of legal restrictions. 

AM2201 (1-(5-fluoropentyl)-3-(1-naphthoyl)indole) C24H22FNO (MW=359.17, structure at right) is a synthetic cannabis compound that acts as a potent agonist for the cannabinoid receptors CB1 and CB2. Its binding affinity to the CB receptors (activity) is about 15-40 times greater than of tetrahydrocababinol (THC) itself, which is the main natural active ingredient found in cannabis. 

The analysis of synthetic cannabis such as AM2201 is relatively simple and can be performed with any standard GC-MS. However, it requires sample preparation which often takes more time than is generally available in busy forensic laboratories. Thus, the main challenge in synthetic cannabis analysis is how to perform it with minimal sample preparation and chromatography time.

In this post we show the fast sample preparation of herb leaves for the analysis of AM2201 using the 5975-SMB GC-MS.

Very Fast Heroin Analysis – The Role of Flow Programming

Aviv Amirav, Professor of Chemistry at Tel Aviv University and Director – Aviv Analytical 

Introduction 

Forensic laboratories are often confronted with a need to analyze hundreds of "white powders" for the presence of drugs of abuse or otherwise to determine their harmless nature. However, a typical "fast" analysis utilizing a standard GC-MS can take 20 minutes (full analysis cycle time including chromatography and cooling back for the initiation of next analysis). Thus, there is a growing need for improved instruments and methods that are capable of much faster analysis cycle times, while retaining good separation and high quality mass spectra for identification purposes.    

Heroin, like many other drugs of abuse, is sold in the streets as a powder mixture which typically contains paracetamol (also named acetaminophen) and caffeine as its major ingredients and a few percents each of 6-monoacetylmorphine (coeluting with some acetylcodeine), heroin, papaverine and noscapine in order of their GC elution times. Thus, a fast street heroin analysis must preserve the proper separation of all its major ingredients while providing full separation of the heroin itself for its quantitation and eluting the last to elute noscapine and anything else that might otherwise contaminate the column. 

In this post we present the details of our rapid analysis of heroin.

Sample Identification – Which is a Better Method and Instrument, GC-MS with its Library Search or LC-HR-MS with the Provision of Elemental Formula?

Aviv Amirav, Professor of Chemistry at Tel Aviv University and Director – Aviv Analytical 

Introduction

A common method of sample identification involves the use of GC-MS with its electron ionization mass spectra and automated library search and identification software. However, a growing portion of sample compounds is not amenable for GC-MS analysis thus the use of LC-MS, particularly with high resolution time of flight MS is growing. The identification method used with such LC-HR-MS instruments is based on the provision of elemental formula. Consequently, interesting questions with practical implications are which of the above identification methods and instruments is better and whether LC-HR-MS can fully replace GC-MS or the later has intrinsic value that LC-HR-MS does not provide.  

In this post we discuss these questions and try to provide answers.