Category Archives: Chromatography Quiz

Chromatography Quiz No. 6

Chromatography Quiz #5 Results
We would like to congratulate the grand prize winner of our last newsletter’s Carbamate Chromatography Quiz: June Black from the Pennsylvania Department of Environmental Protection! 
She has won, and will shortly be receiving, an extensive California Wines Gift Basket!  Additionally, for this quiz all of our participants will each be receiving a $25 gift card from Bevmo! Again, we would like to thank you all for your submissions.  
The correct answer for the modified Carbamate chromatogram: The system was improperly equilibrated at a higher percentage of methanol (50:50 Water:Methanol) prior to injection.  After injection, the gradient program began with normal starting conditions (85:15 Water:Methanol). For the less retained compounds, the improper conditions on the column at the time of injection will push them through faster, causing coelutions.  Longer retained compounds are less affected by starting conditions of the column, and impacted more by the gradient (which was correct) so you see less of an effect on the later part of the chromatogram. 
Thank you! 
Pickering Labs
Chromatography Quiz #6:
Identify the error made when running the Aflatoxins chromatogram below and win a prize!  Simply email your answer as well as your full contact information to Rebecca at rlsmith@pickeringlabs.com by March 31st in order to win.  You will receive email confirmation that your submission has been received.  The troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission). 

Aflatoxins Analysis by AOAC Official Method 2005.08
LCTech Standard: 0.25 ng B2, G2 and 1.0 ng B1, G1 injected on-column in both chromatograms
LCTech Analytical Column: 150 x 4.6 mm; RP C18 (P/N 10522)
LCTech Guard Column: 8 x 4 mm (P/N 10523; holder P/N 10750)
Normal Operating Conditions: (for reference only, condition changes may be reflected in chromatogram)
Column Temperature: 36 °C
Mobile Phase: Water/methanol/acetonitrile 55/30/15
Isocratic Flow rate: 1.3 mL/min
Post-column conditions:
Photochemical Derivatization: 254nm UV low pressure lamp (LCTech UVE derivatizer, Pickering P/N 1100-3347)
Detection: Fluorometer:  ex 365 nm, em 460 nm

Chromatography Quiz No. 5 and Results from Quiz 4

Chromatography Quiz #4 Results
Congratulations to the grand prize winner of our last newsletter’s Amino Acid Chromatography Quiz: Matthew Hartz from Underwriters Laboratories!

He has won, and will shortly be receiving, a $150 gift card to Dick’s Sporting Goods! Additionally, for this quiz our other participants will each be receiving a $20 gift card from Amazon.com. Thank you all for your submissions!

The correct answer for the modified Amino Acid chromatogram: the guard column has been contaminated with proteins. The dirty guard causes poor peak shape and loss of resolution on key pairs of amino acids. Replacing the guard will restore the chromatography.

Thank you!
Pickering Labs

Chromatography Quiz #5:

Identify the error made when running the Carbamates chromatogram below and win a prize! Simply email your answer as well as your full contact information to Rebecca at rlsmith@pickeringlabs.com by December 15th in order to win. You will receive email confirmation that your submission has been received. The troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission).

Carbamate Analysis for US EPA Method 531.1

Pickering Standard: 1700-0063 Carbamate Test Mixture, 2.5 µg/mL, 10 µL injection

Pickering Column: 1846250 Carbamate Column, C18, 4.6 x 250 mm

Normal Operating Conditions: (for reference only, condition changes may be reflected in chromatogram)

Column Temperature: 42 °C

Flow rate: 1 mL/min

Eluent Gradient:

TIME
WATER
MeOH %
0
85
15
1
85
15
44
25
75
44.1
0
100
49
0
100
49.1
85
15
57
85
15

Post-column conditions:
Reagent 1: Hydrolysis reagent CB130

Reagent 2: 100 mg of OPA, 2 g Thiofluor™ in 950 mL of CB910

Reactor 1: 100 °C, 0.5 mL

Reactor 2: ambient. 0.1 mL

Reagent flow rates: 0.3 mL/min

Detection: Fluorometer ex 330 nm, em 465 nm

For an example of a Good Carbamate Chromatogram, Click Here

Chromatography Quiz No. 4

Chromatography Quiz #3 Results
Congratulations to the grand prize winners of our last newsletter’s Glyphosate Chromatography Quiz: Jim Balk from Nebraska DHHS Public Health Environmental Laboratory, Matthew Hartz and Keena Njoroge from Underwriters Laboratories, and Narjes Ghafoori from the County of Los Angeles Environmental Toxicology Laboratory! They have won, and will shortly be receiving from Apple.com, a new iPod Shuffle! Additionally, for this third quiz all of our participants will be receiving a $10 gift card from iTunes. Thank you all for your submissions!

The correct answer for the modified Glyphosate chromatogram: the Glyphosate ‘doublet’ is caused by injecting a sample at basic pH. An improperly buffered sample extract at a large injection volume will not mix with the mobile phase sufficiently to create the acidic pH necessary for Glyphosate to be at the proper single charge state, impacting the interaction between Glyphosate and the active
sites on the column resin. Adding a couple drops of Restore TM(pH 1.3) to the sample before injection will eliminate the ‘doublet’ and return proper peak shape.
Thank you!
Pickering Labs

Chromatography Quiz #4:
Identify the error made when running the Amino Acids chromatogram below and win a prize! Simply email your answer as well as your full contact information to Rebecca at rlsmith@pickeringlabs.com by September 30th in order to win. You will receive email confirmation when your submission is received, and the troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission).

Amino Acid Analysis of Physiological Fluids
Pickering Standard: 011006P Native Sample Standard 0.25 µmole/mL, 10 µL injection
Pickering Column: 0354100T High Efficiency Lithium Cation-exchange Column, 4.0 x 100 mm
Pickering Guard Column: 0352020, 2.0 X 20 mm

Normal Operating Conditions: (for reference only, condition changes may be reflected in chromatogram)

Column Temperature: 37 °C
Flow rate: 0.35 mL/min

Eluent Gradient:

TIME….Li275%…….Li750%…….RG003%
0…………100……………0………………0

12……….100……………0………………0
48………..65…………….35…………….0
90………..0………………100…………..0

95………..0………………100…………..0

120………0……………….94……………6

122………0……………….94……………6

122.1…..100……………0………………0

140……..100……………0………………0



Post-column conditions for amino acid analysis:
Reagent 1: Trione


Reactor 1: 130 °C, 0.5 mL
Reagent flow rate: 0.3 mL/min

Detection: UV-Vis Detector: 570 nm for primary amino acids, 440 nm for secondary amino acids


You can find an example of a good chromatogram on our website. Either click on the link, or go to www.pickeringlabs.com

RESULTS: Chromatography Quiz Number 2 (Amino Acids)

Congratulations to the Grand Prize Winner of our Newsletter’s Amino Acid Chromatography Quiz: Mary Barnes from Marin General Hospital!

She has won, and will shortly be receiving from Amazon.com, a new Kindle Wireless Reading Device and leather book cover!

The correct answer for the modified Amino Acid chromatogram: we did not allow the instrument proper equilibration. The column was equilibrated using a mixture of Li275 and Li750 buffers, and the higher starting pH caused peaks in the beginning of the chromatogram to come too early and co-elute. A similar chromatogram can also be caused by a higher pH of the sample or first buffer or an insufficient equilibration time between runs.

Also, we are extending our deadline for the Chromatography Quiz Number 3 (Glyphosate) until July 15th – so please get your entries in! Rebecca will accept submissions to rlsmith@pickeringlabs.com and confirm via email that she has received your answer.

Thank you and Good Luck!
The Pickering Labs Team

(Kindle image copyright Amazon.com)

Chromatography Quiz Number 3

Reminder: Please resubmit your answers to last quarter’s Amino Acid Chromatography Quiz by June 1st to be eligible for a prize. You can find that quiz located on our Blog: http://pickeringlabs.blogspot.com/2010/01/chromatography-quiz-no-2.html

Chromatography Quiz #3
Identify the error made when running the Glyphosate chromatogram below and win a prize! Simply email your answer and your full contact information to Rebecca at rlsmith@pickeringlabs.com by July 1st in order to win. You will receive email confirmation when your submission is received, and the troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission).

Glyphosate Analysis for US EPA Method 547
Normal Operating Conditions: (for reference only, changes may be reflected in chromatogram)

Customer’s Glyphosate Standard: 25 ppb, 100 µL injection

Pickering Column: 1954150 Cation-exchange Column for Glyphosate Analysis, 4 x 150 mm

Column Temperature: 55 °C
Flow rate: 0.4 mL/min

Eluent Gradient:

Post-column conditions for pesticide analysis:
Reagent 1: Oxidizing reagent – 100uL of 5% Sodium Hypochlorite in 950mL of GA116
Reagent 2: 100 mg of OPA, 2 g Thiofluor™ in 950 mL of GA104

Reactor 1: 36 °C, 0.5 mL

Reactor 2: ambient. 0.1 mL
Reagent flow rates: 0.3 mL/min

Detection: Fluorometer ex 330 nm, em 465 nm

Chromatography Quiz No. 2

Congratulations to the winners of our last newsletter’s Chromatography Quiz: Matthew Hartz, Jamie Palmer, and Keena Njoroge from Underwriters Laboratories, Sudheer Reddy from Chemtex, and Becky Canela from Environmental Laboratory Services!

They’ve each won, and will shortly be receiving from Gifttree.com, two dozen irresistible cookies in five flavors: White Chocolate Hazelnut, Snickerdoodle, Peanut Butter, Oatmeal Raisin, and Chocolate Chip.

The correct answer for the modified Carbamates chromatogram: we reversed the two reagents. The OPA reagent was pumped in the Reagent One position, and the Hydrolysis reagent was pumped in the Reagent Two position. Thus 1-Naphthol, which is naturally fluorescent, appears full-sized. The other Carbamate peaks have different sizes due to their varying rate of hydrolysis – the high pH of the OPA reagent will allow for some but not complete hydrolysis prior to detection.

Chromatography Quiz: Amino Acid Analysis

Identify the error made when running the Amino Acids chromatogram below and win a prize! Simply email your answer and your full contact information to Rebecca at rlsmith@pickeringlabs.com by March 1st in order to win. The troubleshooting answer and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission).

Amino Acid Analysis of Physiological Fluids:

Pickering Standard: 011006P Native Sample Standard 0.25 µmole/mL, 10 µL injection

Pickering Column: 0354100T High Efficiency Lithium Cation-exchange Column, 4.0 x 100 mm

Normal Operating Conditions: (for reference only, condition changes may be reflected in chromatogram)

Column Temperature: 36 °C

Flow rate: 0.35 mL/min

Eluent Gradient:

Post-column conditions for amino acid analysis:
Reagent 1: Trione
Reactor 1: 130 °C, 0.5 mL
Reagent flow rate: 0.3 mL/min

Detection: UV-Vis Detector, 570nm for primary amino acids, 440nm for secondary amino acids
Hint: Assume in this case that both Guard and Analytical column are good. To see a standard Amino Acid chromatogram, click here