Analytical Instrument Documents

Time-of-flight mass spectrometry has the advantages of high resolution, high sensitivity, and high mass accuracy but with relatively narrow dynamic range if a TDC (Time-to-Digital Converter) is used as a data acquisition system. This disadvantage of narrow dynamic range hinders the applications for isotope ratio enrichment measurement. Recently, a new LC/TOF-MS system was introduced that achieved a wide dynamic range by using an ADC (Analog-to-Digital Converter) instead of a conventional TDC. We used this system to evaluate the measurement of phenylalanine (Phe) isotope ratio enrichment. The accuracy, reproducibility, and sensitivity for the method were determined. The method is simple, rapid, and accurate and presents an attractive alternative to traditional GC/MS applications.

Haloacetic acids (HAAs) are disinfection byproducts (DBPs) of the chlorination of drinking water. Dichloroacetic acid and trichloroacetic acid are animal carcinogens. We present an ion-pair HPLC and negative electrospray ionization mass spectrometry (ESI-MS) method with a “function-switching” feature for analysis of all 9 haloacetic acids, monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), monobromoacetic acid (MBAA), bromochloroacetic acid (BCAA), dibromoacetic acid (DBAA), bromodichloroacetic acid (BDCAA), trichloroacetic acid (TCAA), chlorodibromoacetic acid (CDBAA), and tribromoacetic acid (TBAA). JEOL MassCenter™ software can switch different MS settings by the time course. This “function-switching” feature enables each HAA to be analyzed under its optimized MS conditions so that the highest sensitivity can be achieved. Using triethylamine (TEA) as an ion-pairing reagent, a good HPLC separation of all 9 HAAs has been achieved. The optimized MS conditions for each HAA were evaluated.

Nano-LC/MS has demonstrated many advantages, including lower sample consumption, higher mass sensitivity and less matrix effect. Here, we introduce a very simple method to convert regular AccuTOF™ LC system into a nano-LC/MS system without high cost. An application of peptide analysis was used as an example to test the nano-LC/MS system. The RSD of retention time for gradient elution is less than 1%.

The JEOL AccuTOF™ LC/MS system offers easy exact-mass measurements and elemental composition determinations. A robust design and stable time-of-flight mass analyzer are combined with a detection system that provides high sensitivity and high dynamic range. Unlike other API/TOF mass spectrometer systems, the AccuTOF™ provides excellent linearity and mass accuracy over a wide range of analyte concentrations. To demonstrate the potential of the AccuTOF™ for automated exact mass measurements, a variety of small-molecule drug samples were measured by using a macro that allows the user to submit samples for unattended elemental composition determinations. Samples were introduced by using the LC autosampler. The macro applied an automatic drift (“lock mass”) correction to the reserpine reference standard and printed out elemental compositions for user-specified elemental limits. The results show high accuracy and stability regardless of sample concentration.

The AccuTOF™ high-resolution time-of-flight mass spectrometer provides powerful qualitative and quantitative tools that can be applied to HPLC/MS analysis of polyphenols and other compounds in tea. The combination of high-pressure liquid chromatography (HPLC) with high-resolution time-of-flight mass spectrometry (TOFMS) provides powerful capabilities for chemical analysis. HPLC with UV detection relies on wavelength and retention time for peak identification. Here we show how the AccuTOF™ TOFMS with its unique high dynamic range detection system can be used to determine polyphenols (such as catechins), caffeine and related compounds, amino acids, and vitamins in different teas.

For identification of drugs of abuse in forensic science, the unambiguous identification of chemical substances is crucial. The new AccuTOF™ Dual ESI LC/TOF-MS system offers easy exact-mass measurements and elemental composition determinations. A robust design and stable time-of-flight mass analyzer are combined with a detection system that provides high sensitivity and high dynamic range[1]. We used this system for analyzing the samples of drug substances containing the opiates and stimulants. The detection limit for codeine is 1.25 pg/μL. The mass accuracy is smaller than 3 ppm over a wide concentration range, from 1.25 pg/μL to 10 ng/uL.

Acrylamide has been shown to cause cancer in animal studies. It has also been shown to cause nerve damage in people who have been exposed to very high levels at work. In April 2002 the Swedish National Food Authority reported the presence of elevated levels of acrylamide in certain types of food processed at high temperatures. Since then, acrylamide has been found in a range of cooked and heat-processed foods in many countries including the United States [1]. In order to assess acrylamide risk to humans, food levels need to be measured accurately. This prompts the need for development of analytical methods for acrylamide analysis. The US Food and Drug Administration has published an LC/MS/MS method for acrylamide [2]. Due to the low molecular weight of acrylamide, GC/MS has also been used for its analysis [3, 4]. However, GC/MS requires time-consuming derivatization. Here, we describe a simple and rapid LC/Time-of-flight MS method with accurate mass measurement and “in-source CID” fragmentation for acrylamide analysis.

Advances in mass spectrometry are enabling analysis of micro samples and unknown components that were not observable before. As the volume of information acquired from mass spectrometry increases, researchers are calling for simple techniques to analyze the numerous components observed, and as a result, there is a rise in demand for comprehensive analytical techniques including multiple classification analysis. In this work, we analyzed 2 samples in a high resolution GC-TOFMS, using EI, the most widely used ionization technique for GC-MS, and compared the data acquired by using a comprehensive analytical technique.

Petroleum waxes are a class of hydrocarbons that are solid at room temperature and are classified by the Japan Industrial Standards (JIS K2235) into 3 types: paraffin wax, micro crystalline wax, and petrolatum. A typical micro crystalline wax contains hydrocarbons having a carbon number of 30 to 60 and molecular weights between 500 and 800. In addition to paraffins, these waxes also include large quantities of isoparaffins and cycloparaffins. Field desorption (FD) is an ionization technique that utilizes the tunneling effect of electrons in the presence of a high electric field. The sample is applied directly onto an FD emitter filament, and then an electric current is applied to the filament to produce a high electric field across the emitter surface (including the whisker tips) to desorb and ionize the samples. As a soft ionization technique that minimizes fragmentation and produces molecular ions, FD has been previously used for analyzing refractory compounds and high molecular weight polymers. In this work we ionized a micro crystalline wax by using a JMS-T100GC AccuTOF-GC with FD ionization to do a sample type analysis that was based on the mass and intensity of the resulting ions.

JEOL has developed a unique EI/FI/FD combination ion source for the “AccuTOF GCv 4G”, a high- resolution GC-time-of-flight (TOF) MS system. This unique ion source provides the capabilities of GC/EI, GC/FI and FD measurements without having to break vacuum in order to switch between each ionization mode. Additionally, this combination is particularly powerful in that it provides library searchable fragmentation information by using EI and high mass accuracy molecular ion information by using FI and FD. In this work, we measured an antioxidant additive by using each ionization mode available on the AccuTOF GCv 4G combination ion source (EI/FI/FD).


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