Tag Archives: quiz

Chromatography Quiz #26

Chromatography Quiz #25 – B@$eL!nE Noise! — Results

Pickering Labs would like to congratulate the winners of our last newsletter’s Baseline Noise Quiz: Joel Fray from Colorado Analytical Laboratories, Jim Balk from Nebraska DHHS Public Health Environmental Laboratory, Narjes Ghafoori from LA County Environmental Toxicology Lab, Hossein Hajipour from Texas Dept. of Health Services Laboratories, and Tom Schneider from Suffolk County Water Authority.

They have each won and will shortly receive a decadent Chocolate Dream Gift Basket! Created by Cherry Moon Farms, this lovely basket is the ultimate assortment of chocolate sweets that will surely delight! Congrats to our quiz winners and enjoy the goodies!

Thank you all for your submissions! 

The correct answer to the Amino Acids Baseline Noise Quiz:

The zoomed baseline exhibited sine wave with regular oscillations at frequency of about 6 sec. This type of pattern is characteristic to HPLC pump noise as reciprocating HPLC pump moves to deliver the flow of eluants through the column.  If pump is operating normally, the oscillations are very small and will not show as baseline noise. But if the pump has dirty/bad check valves or old/poorly installed seals, the noise increases. In our case, the HPLC pump check valves were bad and needed replacement. 

Chromatography Quiz #26: Shifting Retention Times – Carbamates

What is causing the retention time shift in the chromatogram below?  Simply email your answer as well as your full contact information to Rebecca at rlsmith@pickeringlabs.com by May 1st, 2017 in order to win.  You will receive email confirmation that your submission has been received.  The answer to the quiz and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission). 

Carbamates Analysis – Shifting Retention Times

Pinnacle PCX post-column instrument is being used, in a traditional HPLC setup as recommended by Pickering Laboratories. The quiz question: what is causing the shifting retention times? 

Post-column conditions for carbamates analysis:

Reagent 1: CB130
Reagent 2: CB910/Thiofluor/OPA
Reactor: 100 °C, 0.5 mL
Reagent flow rate: 0.3 mL/min
Injection volume: 10uL

FLD Settings:

λex 330 nm
λem 465 nm

HPLC Flowrate: 1.0 mL/min
Column Temperature: 42 °C

Good Chromatogram

Bad Chromatogram

 

Chromatography Quiz #23

Chromatography Quiz #22 Results

Pickering Labs would like to congratulate our winners of our last newsletter’s AAA quiz: Narjes Ghafoori from LA County Environmental Toxicology Lab, Joy Gottlieb from New Mexico Department of Health Scientific Lab Division, Tom Schneider from Suffolk County Water Authority and Helene Lachance from Shur-Gain Nutreco!    

contest-prizeThey have each won and will shortly be receiving: a Picnic Basket Gift Tin from Harry & David!  From their webpage: Celebrate the season with this gourmet gift basket, featuring a wonderful assortment of snacks, including fruit, meat, cheese, and crackers perfect for picnics and lunches in the park. In addition to our remarkably juicy Royal Verano Pears, we're offering a range of picnic delights, like white cheddar cheese, hickory smoked summer sausage, peanut butter pretzels, sweet raspberry galettes, and more. Packaged in an exclusively designed picnic-ready tin, this gift is ready to help you make any occasion a special one

We hope our quiz winners enjoy their prizes and the springtime weather!

 

Thank you all for your submissions!  

 


The correct answer to the Carbamates Analysis quiz: 

The answer for last quarter’s quiz was: incorrectly prepared reagent.  We prepared our “hydrolysis reagent” with CB910 instead of CB130.  The hydrolysis reagent CB130 is at a pH of 12.5, which is much more basic than our OPA diluent CB910 at a pH of 9.1.  From our Carbamates Manual: The separated carbamates are first saponified by NaOH at 100°C to release an alcohol, carbonate, and methylamine.  In the second post-column reaction, methylamine reacts with OPA and Thiofluor to form the highly fluorescent derivative.  So, if there is insufficient NaOH present for the first reaction, some of the carbamates do not fully hydrolyze.  

Chromatography Quiz #23: Polyether Antibiotics Analysis

What caused the noise for the blue signal in the troubleshooting chromatogram below?  Simply email your multiple choice answer as well as your full contact information to Rebecca at rlsmith@pickeringlabs.com by July 1st, 2016 in order to win.  You will receive email confirmation that your submission has been received.  The answer to the quiz and winner congratulations will be published in the next issue (to be anonymous, please notify Rebecca in submission). 

Polyether Antibiotics Analysis

Pinnacle PCX post-column instrument (two-pump) is being used in a traditional HPLC setup as recommended by Pickering Laboratories.  The reference chromatogram and troubleshooting chromatogram are both shown.

Narasin Standard: 2.5 µg/mL, 100uL injection

Pickering Column: 2381750, Polyether Column, C18, 4.6x250mm

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

Column Temperature: 40 °C
Flow rate: 0.7 mL/min
Isocratic: 90% Methanol, 10% of 5% Acetic Acid solution in water

Post-column conditions:

Reagent 1: Concentrated Sulfuric Acid / Methanol (4:96 v/v)
Reagent 2: 60g of Vanillin in 950mL of Methanol
Reactor 1: Ambient, 0.1mL
Reactor 2: 90 °C, 1.4mL
Reagent flow rates: 0.3 mL/min

Black (Reference) Signal:

DAD detector 520nm with bandwidth of 4nm
No reference wavelength
Sampling rate >0.10min (2.0 S response time) (2.5Hz)

Blue (Troubleshooting) Signal:

DAD detector 520nm with bandwidth of 4nm
Reference wavelength of 360nm
Sampling rate >0.05 min (1.0 S response time) (5HZ)
Can you identify the error made when running the chromatogram?

Multiple Choices:

A) Bad lamp
B) Reference Wavelength
C) Sampling rate
D) All of the above

Troubleshooting:

quiz-chart