Translator for HPLC HINTS and TIPS for Chromatographers

Saturday, May 11, 2019

Useful Windows Command Line Programs and Shortcuts

  • Warning: These commands and shortcuts should only be used by experienced users who both accept and understand the risks involved. Please backup all systems, programs, applications, data and files before using any utility program or command line.
Command Names:


Command Line Shortcut (to exit from the command line, type exit):

            cmd



View Network Address (shows your local IP address)

ipconfig



View IP address Routes (shows Interface list with IPv4 and IPv6 Route Tables)

            netstat –r

Ping an Address or Host (From the command prompt, type "ping" followed by the IP or name)
           
           ping hostname     ( e.g. ping 192.168.254.01 )
           ping IP address    ( e.g. ping chiralizer.com )

Find Devices on Network (shows device IP and MAC address. *Useful when you know the MAC address but not the IP it was assigned to)

            arp -a



System Config:

            msconfig



Windows Version:

            winver



Add Hardware Wizard:

            hdwwiz



Control Panel Shortcut:

            control



Device Manager Shortcut:

            devmgmt



Disk Cleanup:

            cleanmgr



Display:

            dpiscaling



Print Manager Shortcut:

            printmanagement



Windows Explorer Shortcut:

            explorer


Saturday, March 23, 2019

HPLC to UHPLC Conversion Notes (Gradient Time Program Adjustment)

In an earlier article we discussed how to adjust the flow rate, injection volume and column dimensions when scaling an HPLC method UP or Down. The formula's needed to do this are fairly simple. If we adjust for changes in the column dimensions or flow rate, what types of changes are needed to adjust the gradient time? The formula to make this adjustment is also very simple. Here is the information you need.

Terms Used in Formula:


Time in minutes, Gradient (Initial): Tg1
Time in minutes, Gradient (New):   Tg2
Flow Rate in mL/min, Column (Initial): Fc1
Flow Rate in mL/min, Column (New): Fc2
Column Diameter, mm (Initial): Dc1
Column Diameter, mm (New): Dc2
Column Length, mm (Initial): Lc1
Column Length, mm (New): Lc2


  • Tg2 = Tg1 x (Fc1/Fc2) x ((Dc2 x 2) / (Dc1 x 2)) x (Lc2 x Lc1)

Here is an example problem to solve for. 

If we start with a flow rate of 1.000 mL/min (Fc1) on a 4.6 x 250 mm column with 5 micron support (Dc1 & Lc1) and have an initial Gradient Time of 10 minutes (Tg1), then what would the new gradient time be if we switched to a sub 2 micron support in a 2.1 x 50 mm column (Dc2 & Lc2)at 0.200 mL/min (Fc2)? 

To solve the equation we will plug-in the values for each part of the equation separately, then multiply them to obtain the result.

  (Fc1/Fc2):    1.000/0.200 = 5

  (Dc2 x 2) / (Dc1 x 2)  5.76/21.16 = 0.21

   (Lc2 x Lc1) = 50/250 = 0.20

  Tg2 = 10 x 5 x 0.21 x 0.20 

  Tg2 = 2.10 (or 2.10 minutes)

If a 2.1 x 50 mm column was substituted for the 4.6 x 250 mm AND the flow rate was changed from 1.000 mL/min to 0.200 mL/min, then the initial programmed gradient time of 10 minutes would be changed to 2.1 minutes

Saturday, February 9, 2019

Part 3, Overlooked HPLC Chromatography Standard Operating Procedures (SOP's); Routine Backup of HPLC Data, Methods And Related Data:

As a scientific consultant, I often review clients overall laboratory operations and make recommendations regarding documentation and procedures which may improve their accuracy and results. Some of these recommendations come in the form of SOP's.

Here is the third and final example of a 'must have' SOP' which should be in place for any laboratory performing HPLC analysis.

Part 3 of 3:
Routine Backup of HPLC Data, Methods And Related Data:

Another area which is often overlooked and can have disastrous consequences when ignored relates to regular software backups. Successful management of analytical instruments requires that all of the software which is required to operate and maintain them on a daily basis is safely backed up. This should include any needed patch files, hot-fixes or service packs too. Separate copies of all key software applications and licenses should be stored off-site, in a safe location where they can be assessed if and when needed by authorized individuals. This location may be another office location or even a home. It might even be located on a separate computer server or on the 'cloud'. However, for it to be a safe location, it must be off-site and protected from loss due to a hard-drive crash, data corruption, flood, fire, theft, earthquake or other disaster.


  • Regular backups (automated are best!) of all acquired data, methods and related information needed to restore the data should be performed on a daily basis. Backups must also be tested and verified on a periodic basis (if you do not verify them, how do you know that they work?). Verification also serves to train you how to restore damaged data or software which is something that you do not want to learn how to do when you actually need it for the first time.
  • You may also wish to address the use of suitable electrical power backup modules (UPS) to protect the computers used to acquire data from and run methods from power outages or surges. An article which addresses this topic can be found at this, "Power and Surge Protection for Computers & Analytical Instruments (e.g. Uninterruptible Power Supply AKA UPS)" LINK.
  • SOP's describing Backup and Restoration of key Applications and Data should be created which detail the types of backups made, the frequency of backups, which applications and/or files are backed up, using which backup software products or applications, the restoration process used and how often it should be tested to ensure that you can still restore your data.

Make sure you have several people review the draft SOP's before approving. Sometimes what appears clear to you may in fact have a different meaning to someone else. Clear procedures should contain enough detail that people with different backgrounds will each carry out the procedure in the same manner. Often, these types of documents will go through many drafts and even after approved, should also be open to future suggestions to make them even better.

Saturday, January 5, 2019

Part 2, Overlooked HPLC Chromatography Standard Operating Procedures (SOP's); HPLC System Preventative Maintenance Frequency & Procedure (PM)

As a scientific consultant, I often review overall laboratory operations and make recommendations regarding documentation and procedures which may improve their accuracy and results. Some of these recommendations come in the form of SOP's.

Here is the second example of a 'must have' SOP which should be in place for any laboratory performing HPLC analysis. 

Part 2 of 3:
HPLC System Preventative Maintenance Frequency & Procedure (PM):
 
Regular cleaning, inspection and maintenance of the modules which make up the HPLC system should be carried out on a regular schedule. The frequency will depend on how the system(s) are used and what part lifetimes are typical. Preventative maintenance must not be confused with repairs or servicing to restore operation of the system after damage has occurred. Many companies perform PM services every 4, 6 or at most, 12-months. 
  • PM procedures should include the inspection, cleaning and replacement of normal wear and tear parts such as: filters, frits, valve seals, injection seats/seals, pistons, piston seals and lamps. The PM provides an opportunity to inspect the condition of the modules and parts to insure they are operating properly. The goal should be to replace worn parts before they contribute to poor reproducibility or a failure. If the parts are found to be damaged, then that would be considered 'service' not maintenance and indicates that previous data collected on the system may be unreliable. Don't delay performing PM services on your instruments. Regular maintenance is a requirement. Your related SOP's should address which modules require regular maintenance ( A policy SOP), how often it is performed (A frequency SOP), who performs it and what training have they had (Training Requirements SOP. Also document in the specific Instrument's Logbook), which parts and tools are required (The actual PM SOP for the module) and what tests are performed to insure that it was done correctly (Separate SOP's for each Test).

Make sure you have several people review the draft SOP's before approving. Sometimes what appears clear to you may in fact have a different meaning to someone else. Clear procedures should contain enough detail that people with different backgrounds will each carry out the procedure in the same manner. Often, these types of documents will go through many drafts and even after approved, should also be open to future suggestions to make them even better.