Dear Ali,

The following is a good HPLC method for resorcinol. For details see attached publication.

j. Cosmet. Sci., 50, 315-325 (September/October 1999)

Determination of phenol, resorcinol, salicylic acid and

-hydroxy acids in cosmetic products and

salon preparations

RONALD L. YATES and DONALD C. HAVERY, U,S, Food and

Drug Administration, Office of Cosmetics and Colors, 200 C St. SW,

Washington DC 20204.

Accepted for publication August 31, 1999.

Synopsis

A method is described for the determination of glycolic acid, lactic acid, citric acid, phenol, resorcinol, salicyclic acid, tx-hydroxyoctanoic acid, and tx-hydroxydecanoic acid in commercial creams and lotins. A mixture of the product and a filter aid was extracted with an appropriate solvent. The extracts were cleaned up by either solid-phase extraction chromatography or ion-exchange chromatography. The resulting extracts were analyzed by HPLC using a C 8 column. Recoveries of citric acid, lactic acid, phenol, resorcinol, and salicylic acid added to a simple emulsion ranged from 99% to 102%, while recoveries of glycolic acid averaged 93%. tx-Hydroxyoctanoic acid and tx-hydroxydecanoic acid recoveries from a commercial lotion ranged from 90% to 101%. The results of surveys of commercial products obtained directly from manufacturers, and purchased from salons, retail stores, and through the mail, from 1992 to 1996, are presented

Hoping this will be helpful,

Rafik

Ali,

From the question it was apparent that you already have a HPLC method in place. Could you provide the following details?

It would be easier to provide a reasonable solution if your answers are detailed.

Thanks.

SC

Hi, in addition of publication that mentioned by Rafik above, I have 2 application-notes for analyzing resorcinol and related compounds by HPLC, maybe  you can consider their methods. Best regards

Many Thanks for all your answers.

Some extra info that might help:

• It's a Shimadzu system
• equipped with a diode array UV-detector (SPD-M10AVP)
• using an Alltima C18 column (5 µm; 4.6 mm × 250 mm)
• a mobile phase of methanol/water (1/1, v/v) at 1 mL min-1
• at wavelength 254nm.
• with void time of 1 min (current retention time is around 3.9 min but the baseline is not perfect)

I am mainly looking for a simple fast method that delays the elution a bit and doesn't require a solid phase extraction. Two of the suggested methods elute resorcinol before the first minute, and that might be pretty challenging.

Thanks in advance for all your help, and Please let me know if more info is needed.

well if a compound elutes too fast you decrease the concentration of organic modifier in the eluent. (methanol in your case). If you are running a lot of real samples you probably want to change to an gradient system starting e.g. with 10% MeOH an increase over time (10 mins) to 100% MeOH keep for a few mins (e.g.3) bring back in 30 sec to starting conditions and condition for 2-3 mins. This approach will prvent the system from accumulating lipophillic stuff resulting in shifting retention times.... 

Ali,

You already have a long column. Please check the void carefully. You should have at least 2 min void (if not more). You may try injecting some acetone and monitor at 210 nm.

As far as the actual problem goes, you can try Kai's suggestion. I personally don't think you will have to go from 10% MeOH to 100% MeOH considering the polarity of resorcinol. I will start at 10% MeOH, hold the gradient for 2 min to ensure that the analytes are at the front of the column and subsequently increase the strong solvent to 60% till 6 min. Hold for 2 min. Rapidly increase to 100%  at 9 min hold for 2 mins. For gradient elution, equilibration is critical. I will do at least 3 column volume (if the void is 2 min at 1ml/min, you need to send 6 mL 10% MeOH through the column, therefore, I will do at least 6 min injection delay). Correct equilibration can solve many issues with this type of chromatography.

Hope this helps.

Thanks.

SC

Thank you all for your help.

We solved the issue by reducing the flow rate of the mobile phase to 0.7 ml/min and more importantly modified the mobile phase constitution where the methanol percentage was reduced to 15% only (85% water).

P.S.: We had to run it isocratic because of lab restrictions (we got HPLC with one pump knowing only)

Hi, I'm doing some analysis on hplc with the diode array detector SPD-M10Avp, but I do not get any wavelengths and the baseline has no noise. Please, someone could help me. Appreciate.