Lab Techniques

There are three types of lab techniques that you must know for the MCAT spectroscopy, spectrometry, and separations. Spectroscopy will be either nuclear magnetic resonance (nmr), infrared spectroscopy (IR), or ultraviolet spectroscopy (UV). You will need to understand how mass spectrometry works. Separation techniques will include chromatography, distillation, crystallization, and extraction. 

NMR refers to nuclear magnetic resonance spectroscopy. The nucleus most commonly studied with nmr is the hydrogen nucleus, but it is possible to study the nucleus of carbon-13 and other atoms as well. 

In nmr, the frequency of the electromagnetic radiation is held constant while the magnetic field strength is varied. 

Lateral position on a spectrum is dictated by electron shielding, thus limited predict tions can be made based upon electron-withdrawing and electron-donating groups. 

Something else you should know Aldehyde protons have a very distinctive shift at 9.5 ppm. Watch for it. 

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Just in case you are not familiar with basic laboratory procedures, this chapter will explain them to you. These are the most basic lab techniques and almost every method in this entire book will require many, if not all, of the protocols to follow. So pay attention ... 

To determine the rate behavior of chain growth polymerization reactions, we rely on standard chemical techniques. We can choose to follow the change in concentration of the reactive groups, such as the carboxylic acid or amine groups above, with spectroscopic or wet lab techniques. We may also choose to monitor the average molecular weight of the sample as a function of time. From these data it is possible to calculate the reaction rate, the rate constant, and the order of the reacting species. 

The Amb a 1 concentration of the final purified intermediate bulk is determined by an absorbance method chosen for its precision, accuracy, and simplicity. Because Amb a 1 bulk intermediate will now be conjugated to 1018 ISS (and the number of linked 1018 ISS affects the activity of the resulting AIC), it is essential to quantitate the Amb a 1 concentration accurately and precisely. A significant over- or underestimation of protein concentration will result in an over- or underestimation of the heterobifunctional linker required to activate the protein for coupling to 1018 ISS. The absorbance method, more dependent on well-calibrated instrumentation than lab technique, was chosen because it is an easy procedure to transfer to the production site. Dilution skills are the only requirement for robust performance of a well-developed and validated absorbance method. Hence a contract manufacturing site could readily quantitate Amb a 1 without the... 

Ann Vaughan (lab techniques). Institute of Rural Studies, University of Wales, Aberystwyth, UK... 

Complicated biological systems (bioassays) at trace element concentration levels typical for offshore waters, are subject to serious danger of contamination. Without extreme precautions e.g. Carpenter and Lively (1980) and Fitzwater et al. (1982) found the toxic effect (inhibition of primary production) of contamination by the incubation bottles. Effects of adsorption to walls and particulate matter (sediment) should not be underestimated. Use of clean lab techniques and regular check of the trace element concentrations throughout the (biological) experiments is necessary to get an indication of the actual concentration and possible distribution of the different elements. Depending on the type of experiments it could be possible that other parametes should be known or even controlled pE, PO2, ionic strength, temperature, DOC etc. 

There are other alterations as well to the basic procedures outlined in this chapter and in Chapters 20 and 21, which involve combinations of the PAP, ABC, and LAB methods. For example, a biotinylated antibody can be recognized by an antibiotin antibody, and a linking reagent can be used to bind the antibiotin antibody to a PAP type of complex, or a secondary biotinylated antibody can be employed following the antibiotin step, which could then result in an ABC means of detection. Alternatively, an antiavidin may be used to amplify a LAB technique further. With each successive step, a greater level of amplification can be achieved. However, the possibility of higher background and poorer resolution from severe steric hindrance is also increased. 

Even though you have already taken science classes with lab work, you will find the two types of laboratory experiments in this book organized differently from those you have done before. The first type of lab is called a Skills Practice Lab. Each Skills Practice Lab helps you gain skills in lab techniques that you will use to solve a real problem presented in the second type of lab, which is called an Investigation. The Skills Practice Lab serves as a Technique Builder, and the Investigation is presented as an exercise in Problem Solving. 

The Skills Practice Labs provide step-by-step procedures for you to follow, encouraging you to make careful observations and interpretations as you progress through the lab session. Each Skills Practice Lab gives you an opportunity to practice and perfect a specific lab technique or concept that will be needed later in an Investigation. 

Experimental aspects description of the 2-DE technology a wet-lab technique, from a wet-lab point of view 74... 

Developing proper lab techniques to ensure safety and avoid contamination. 

Up until now, we ve been optimistic about the amount of product obtained from a reaction. We have assumed that 100% of the limiting reactant becomes product, that ideal separation and purification methods exist for isolating the product, and that we use perfect lab technique to collect all the product formed. In other words, we have assumed that we obtain the theoretical yield, the amount indicated by the stoichiometrically equivalent molar ratio in the balanced equation. 

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