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.