WHAT EVERYONE SHOULD KNOW BEFORE HAVING LASIK SURGERY Let us help answer some of the most commonly asked questions ISN’T ALL LASIK THE SAME? No, there are about 140 variations on the Lasik procedure, based upon the equipment used. When the military approved Lasik for astronauts in 2007, they chose iLasik. This represents a specific combination of all-laser equipment, n
59051.qxdRapid Analysis of Residual Solvents
Using Static Headspace Sampling and Stop-Flow GC by Christopher English, Environmental Innovations Chemist, Rebecca Wittrig, Ph.D., HPLC Product Marketing Manager, and Frank Dorman, Ph.D., Director of Technical Development • Resolve 35 residual solvents in 18 minutes.
• Simplify inventory—use one pair of chromatography columns and one set of conditions for all ICH Class I and Class II solvents.
• Complete, easy to install system.
Kit is easily attached to Agilent 6890 GC! The International Conference on Harmonization second (Rtx®-200) column is interrupted briefly (stop-flow pulses) to tune the separation at the includes all ICH Class I and Class II solvents, amounts of residual solvents considered safe in except ethylene glycol (which was not detected pharmaceutical finished goods. The ICH has at 200ppm), at 200ppm each in 5mL of 1,3- published guidelines and daily exposure limits In an analysis on two GC columns in series dimethyl-2-imidazolidinone (DMI) solvent. By for 61 solvents, classified in three groups, there are four possible outcomes for two sam- resolving closely eluting component pairs, Stop- according to their toxicity. Class I solvents are Flow GC enables pharmaceutical laboratories to known carcinogens or environmental hazards, to resolved at the column junction and remain monitor all ICH Class I and Class II solvents be avoided if at all possible. Class II solvents resolved at the end of the ensemble; 2) the two with one pair of chromatography columns and a are less toxic, but their use should be limited.
compounds coelute at the junction, but are Class III solvents have low toxicity or no health- resolved on the second column; 3) the two com- related exposure limit.1 All pharmaceutical prod- pounds are resolved at the junction, but coelute This analysis for 35 residual Class I and Class II ucts must be analyzed for residual solvents, at the end of the column ensemble; 4) the two solvents is rapid, sensitive, and reliable. If you regardless of the matrix, and an enormous num- compounds coelute at the column junction and are required to monitor solvents in pharmaceuti- ber of methods potentially can be required to at the end of the ensemble. For 1) and 2) no cal products, we welcome the opportunity to address the total list of solvents. The complexity adjustment is necessary. For 4) other stationary and high cost of compliance are major hurdles in phase combinations should be investigated to ensure separation on at least one of the two columns. For 3) Stop-Flow GC is appropriate.
1.ICH Guidance for Industry, Q3A Impurities: Residual In February 2004, Teledyne Tekmar developed a Carrier gas flow into the second column is inter- Solvents US Dept. of Health and Human Services,Food and Drug Administration, Center for Drug universal analytical method for extracting and rupted briefly, immediately after one of the two Evaluation and Research, Center for Biologics determining 32 ICH Class II and Class III resid- compounds has crossed the junction, but while Evaluation and Research (CBER). International ual solvents, using static headspace sampling.2 the other compound is still in the first column.
Conference on Harmonization, Dec. 1997.
Simultaneously, Restek chemists were develop- The timing and duration of the stop-flow pulse 2.Wallace, B. and J. Kancler. One Universal Method for ing an approach for resolving the Class I and are set to ensure that the two components Residual Solvents in Pharmaceuticals Using a High Class II solvents, using a new technology known remain separated when they reach the end of Temperature Static Headspace Sample Introduction as Stop-Flow GC, but lacked a sample prepara- the column ensemble. The key to choosing a col- System Application Note 7000-021b.doc, Teledyne tion method suitable for achieving the detection umn ensemble for a specific application is to 3.Wittrig, R.E.; F.L. Dorman, C.M. English, R.D. Sachs, limits required by the ICH.3 By using a Teledyne make separate analyses on each column, to Tekmar 7000HT headspace autosampler unit in ensure that no two compounds coelute on both conjunction with Stop-Flow GC technology, it is possible to achieve resolution, sensitivity, and Special thanks to Brian Wallace of Teledyne rapid sample turn-around times for the Class I Figure 1 is the product of applying three stop- Tekmar for the use of the 7000HT headspace and Class II residual solvents. In Stop-Flow GC flow pulses at the junction point of the column the solvents are separated by passing the sam- ple through a two-column ensemble consisting trichloroethene, acetonitrile, and chloroform.
of a Stabilwax® column and an Rtx®-200 column The other analytes are resolved by adjusting the coupled in series. Carrier gas flow through the carrier gas flow and temperature program, and Stop-Flow GC for Agilent 6890 GCs
Stop-Flow System for use with Cool On-Column EPC(includes: Stop-Flow enclosure, top mounting plate, 1-line weldment, We offer many reference mixes of residual Stop-Flow System for use with Split/Splitless EPC (includes: Stop-Flow enclosure, top mounting plate, 2-line weldment, chromatography supplies catalog, or visit Stabilwax® Column
15-Meter, 0.25mm, ID 0.5µm df, cat.# 10635, 30-Meter, 0.25mm ID, 1.0µm df, cat.# 15053, 2004 vol. 3
800-356-1688 • www.restek.com
Figure 1 Stop-Flow GC provides a rapid, sensitive analysis for ICH Class I and Class II residual solvents.
Teledyne Tekmar 7000HT high temperature static Stabilwax®, 15m x 0.25mm x 0.5µm (cat. # 10635) Rtx®-200, 30m x 0.25mm x 1.0µm (cat. # 15053) 200ppm each component in 1,3-dimethyl-2-imidazolidinone (DMI) 40°C (hold 2 min.) to 55°C @ 4°C/min., to 110°C @ 25°C/min. (hold 2 min.) to 250°C @ 25°C/min. (hold 5 min.) FID #1 at column junction, FID #2 at sample outlet 1mL (standard size, Silcosteel® treated) Stop-Flow Conditions
plumbed through injection port, 1:20 split Restek Stop-Flow System for Agilent 6890 GC with cool on-column EPC (cat. #21168) valve opened 3.00 - 3.15 min., 4.65 - 5.02 min., 5.10 - 5.40 min.
2004 vol. 3
800-356-1688 • www.restek.com
EXPERIMENT 9 (Organic Chemistry II) Pahlavan - Cherif Synthesis of Aspirin - Esterification Materials 125-mL Erlenmeyer flask Melting point capillaries Melting point apparatus Chemicals Salicylic acid Purpose – To learn how to synthesis organic compound such as aspirin and determine the purity of aspirin. INTRODUCTION Organic Chemistr y is the study of c