Chem. 231 – 4/8 Lecture

Announcements

• Set 1 Lab Reports – hand back

• Set 2 Lab Reports– Due 4/10

• Final Exam – April 15th

• Future Mondays (after 4/15)– Set 3 Presentation – 4/29– 4/22 and other Mondays

• can’t start lab at 5:00 in Sequoia 538 (Chem 125 conflict)

• can run lab from 5:30 to 9:00 or• 5:30 to 8:30 plus Wed from 5:00 to 8:00 or• first 30 min of lab in Sequoia 540

Labs – More Details

• Set 2 Lab Reports– Real sample analysis will count for at most

25% of points (less for HPLC lab)• Set 3 Labs

– We have tristearin and tripalmitin that can be used as recovery standards

– We also have old linoleic (C18:2) and linolenic (C18:3) acid standards that can be used as qualitative standards (these standards decompose easily)

– These are in 540 freezer– You should be deciding on your “real” sample

soon and let me know what other equipment or standards you will need

Labs – More Details

• Set 3 Labs – cont.– Tentative presentation and paper due dates– Presentation 4/29 (1 week after finishing lab)– Paper due 5/6– Presentation should be focused on your sample

of interest and should include some literature research (why is this sample of interest and what analysis has been done previously)

Labs – More Details

• Term Project– You should figure out what you plan to do

before next Monday– Two options:

• isolation of significant ingredient from household product (best for 5 to 50% that ingredient)

• use of “new” equipment for analysis of compound from sample (e.g. use of HPLC-fluorescence detection for capsaicin in chile samples or analysis of caffeine in a beverage by SPME-GC-NPD)

– I will have a sign up• limit to number of students using particular

equipment for bulk of work (not a problem for isolation projects)

• only 1 student per household sample/ingredient• you may want to have a back-up compound/plan

Final Exam - Review

• Example posted on-line• 15% of total grade• Can use lab notebook and notes from lab

lecture (including slide)• What to know – from 1/28 lecture

– Understand goals of method optimization and measures of how well that is accomplished

– Basic safety rules– How to transfer data (raw, chromatograms,

and software table data) to Excel– Steps to turning on and off HPLCs and GCs

Final Exam - Review

• What to know – from 2/4 lecture– Understand goals of simple extractions– Know some equipment for the following types

of extractions:• solids into liquids• gases into liquids• gases into solids• removal of solids from fluids• liquid – liquid extraction• solvent reduction

– How Soxhlet extraction works– How gas trapping works– Procedure to use SPME (for gases or liquid

samples)

Final Exam - Review

• What to know – from 2/4 lecture – cont.– Requirements and selection of phases for liquid

– liquid extractions– Purpose of acid/base modifiers in liquid – liquid

extractions• What to know – from 2/11 lecture

– Basic calculations for liquid – liquid extractions (Q, Kp and KD)

– How to test for extraction efficiency and ways to improve extraction efficiency

– Main purpose and equipment with low pressure liquid chromatography and TLC

Final Exam - Review

• What to know – from 2/11 lecture – cont.– How to identify problems in integrating peaks– Some ways to improve peak integration (be

able to describe or give name of control in software)

• What to know – from 2/18 lecture– How to calculate a limit of detection from a low

conc. standard run– Calibration Methods

• main types and rationales for use• how to perform linear least squares analysis• some sources of uncertainty• how to use internal standard and surrogate standard

methods

Final Exam - Review

• What to know – from 2/25 lecture– Advantages to GC methods– Limitation of GC methods to certain

analytes/samples– Requirements to use GC for permanent gases

and non-volatile compounds• What to know – from 3/4 lecture

– SPE use procedure– Basic structure of phenols and monterpenes– Factors to consider when selecting HPLC

solvents– Advantages/disadvantages to low and high

pressure mixing

Final Exam - Review

• What to know – from 3/11 lecture– SPE use procedure– How HPLC pumps and injectors work– How to avoid peak broadening associated with

injection– Know how column dimensions (both GC and

HPLC) affect separation performance– Know the difference in needs between

selective and universal detectors