This handout describes how to prepare a standard gas chromatograph sample. It involves preparing a dilute solution of a somewhat volatile compound and using the GC to assess its purity

Working on a vacuum manifold: See LLP chapter 9.2 for an excellent discussion on working with air-sensitive reagents, including how to use a two-way manifold. De-gassing solvents: The best way to remove water and oxygen from a solvent is to distill it over an appropriate drying agent (such as sodium). This can sometimes be a lengthy (and dangerous)task. Since we

For a two-solvent recrystallization, you should have one solvent (solvent #1) in which your desired compound is soluble at the boiling point. The second solvent(solvent #)should induce crystallization when added to a saturated solution of your compound in the primary solvent. Reference:

X-Ray diffraction is an important and powerful tool for determining the solid state structure of compounds. Modern advances have made data collection and structure solution almost routine for many small molecules To use this technique, however, good quality single crystals are still needed. In this exercise you will experiment with the art of growing single crystals

This is two-day- experiment. Do not start this experiment unless you have two free lab days to complete it.*** Techniques Checklist: Picking the correct eluent Adsorbtion of a crude mixture onto silica gel Separating complex mixtures using gradient elution Pre-lab Discussion: Suggest limited list of eluent solvent systems Discuss sample adsorption and gradient elution strategies

described in these materials are potentially hazardous and require a high lcvel ofsafity training special facilitics and equipment, and supavision by approprinte duals. You bear the sol responsiblity, liability, and risk for the impkemcntation of such safety procedures and measures. MiT shall have no responsibility, liability, ar risk for the content ar implem of ay of the matcrial presented. Legal Notices

equipment and supavision by appropriate individuak You bear the sol responsibility, liability, and risk for the implemcntation of such safety procedures a ares. MIT shall have no responsibility, liability, risk for the content or implementation of of the mat

1. volumetric Techniques: Don' t let inaccuracy hold you back in lab! This video introduces the proper methods for measuring precise volumes of liquid using pipets, burets, volumetric flasks, and syringes

Techniques Checklist m manifold use Manipulations under an inert atmosphere Solvent de-gassing Pre-Lab Discussion and required reading: Air sensitive techniques

藻类植物整个藻体都能吸收营养制造有机物质 ,不需要高等植物那样花相当多的能量消耗在 支持器官上。藻类植物体形态多样,许多种类 要用显微镜或电镜才能观察清楚。形态结构、 繁殖方法也简单。通常以细胞分裂为主,当环 境条件适宜、营养物质丰富时,藻体个体数的 增长非常快速。藻类分布十分广泛,各种水域 中均有。有些种类在小水体和浅水湖泊中常大 量繁殖,使水体呈现色彩,这一现象称为“水 华”(water bloom)有些种类在海水中大量繁 殖,形成“赤潮”(red tide)