Instrumental Issues

R. W. Odom and B. Schueler. Laser Microprobe Mass Spectrometry Ion and Neutral Analysis, in Lasers and Mass Spectrometry (D. M. Lubman, ed.) Oxford University Press, Oxford, 1990. Presents a useful discussion of LIMS instrumental issues, including the post-ablation ionization technique. Several anal)n ical applications are presented. 

CE has suffered from an assortment of common operator errors, which in turn have characterized the technique as not being robust. Like any analytical piece of equipment, there can be hardware and chemistry/operator issues. CE requires a keen background and user knowledge of the technique so as to avoid common problems that may initially be diagnosed as instrumental issues. For the early user of CE, the table below lists some common problems followed by their root causes and corrective actions. Following the suggested corrective actions should help the beginner get the maximum performance out of the CE instrumentation. 

There are a number of limitations on the use of extremes of temperature in HPLC. Clicq et al. [91] note that instrumental issues become increasingly limiting as one goes to very high temperatures and flow rates. They suggest that most separations will occur below 90°C where there are less instrumental constraints. As detailed below, column bleed can limit the selection of columns. Highspeed separations require a faster detector response than many systems allow and constrain extra column volume. This is especially true for narrow bore columns and sub-2 jam particles. In many cases, the additional speed gained above the temperature limits of commercial HPLC ovens will not be worth the additional expense and complexity required. For macromolecules, the effect of extreme pressure can also impact retention time as noted by Szabelski et al. [92]. 

There are also some practical problems connected with the instrumental issues of MS. Most of the sources used in mass spectrometers are so small that it is pos-... 

The reliability of the software in an automated synthesizer is as important as that of the instrument hardware. The software controls most of the tasks of the chemist in the manual synthesis. It runs the instrument, issuing the commands telling how much, when, and where to deliver reagents. The main features of instrument software are the user interface, system control, and system monitoring. 

A bond is a debt capital market instrument issued by a borrower, who is then required to repay to the lender/investor the amount borrowed plus interest, over a specified period of time. Bonds are also known as fixed income instruments, or fixed interest instruments in the sterling markets. Usually bonds are considered to be those debt securities with terms to maturity of over one year. Debt issued with a maturity of less than one year is considered to be money market debt. There are many different types of bonds that can be issued. The most common bond is the conventional (or plain vanilla or bullet) bond. This is a bond paying periodic interest pay-... 

Options on Euro-BUND futures (OGBL). The BUND future is a contract on a notional long-term instrument issued by the German Federal Government with a remaining time to maturity between 8.5 and 10.5 years, bearing a 6% coupon. 

However, it is also possible that an investor may find that there is a negative basis. For example, the credit default swap spread is less than the asset swap level for a cash instrument issued by the same reference entity. This situation may arise in the markets ... 

Schriemer, D. C. and Li, L., Mass Discrimmationin the Analysis of Polydisperse Polymers by MALDI Time-of-Flight Mass Spectrometry. 2. Instrumental Issues, Anal Chem., 69, 4176, 1997. 

A zero-coupon bond is the simplest fixed-income security. It makes no coupon payments during its lifetime. Instead, it is a discount instrument, issued at a price that is below the face, or principal, amount. The rate earned on a zero-coupon bond is also referred to as the spot interest rate. The notation P t, T) denotes the price at time r of a discount bond that matures at time T, where T >t - The bond s term to maturity, T - t, is... 

There are also some practical problems connected with the instrumental issues of MS. Most of the sources used in mass spectrometers are so small that it is possible to also have, for example, a very small inlet for the gas or liquid. In this case, such TLC/MS methods may only be used if they are based on the introduction of samples via a stream of gas. The matrix, together with sample material, may be introduced directly into the MS source. Some types of instruments even allow for the insertion of a whole chromatographic plate into the MS source. 

Schriemer, D.C., Li, L. (1997) Mass discrimination in the analysis of polydisperse polymers by MALDI time of flight mass spectrometry. 2. Instrumental issues. Anal. Chem.,69,AVU>-A %3. 

Although particle characterization is not an ordinary instrumentation issue, some supporting laboratory scale equipment helps even the commercial operation by defining the realistic nature of the particles in each occasion. Thus it is recommended to have a small, say 5 cm in diameter, cold test unit with a flowmeter and pressure sensors. 

UHPLC Instrument Issues Encountered During Method Transfers... 

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