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ACCTA, Inc. Methods

Caffeine, Sorbate, and Benzoate by HPLC

A "Monster" method for analyzing energy drinks and other liquids.


Sorbate and benzoate are common additives in many food products, including juices and energy drinks. Existing analytical methods for sorbate and benzoate are not optimized for current HPLC technology. The columns are too long (often 250 mm), the mobile phase typically requires preparation of buffers, and retention times are longer than they should be. Such systems reduce the lifetime of your HPLC components (all mobile phases with dissolved solids do this), use too much mobile phase (increasing purchase and disposal costs), and make you wait for an answer. In a brief literature survey, we were able to find multiple methods, but all showed analysis times of 10 - 15 minutes.

What is the problem? In a word: selectivity. Sorbate and benzoate have almost identical retention times on the most common stationary phases. To get a good separation, you need a long column, and you must use conditions that produce long retention times.

We have developed a new method that eliminates these problems. With our knowledge of selectivity and method development experience, we have identified four different columns, from two different manufacturers, using two different mobile phase options, that produce a good separation of sorbate and benzoate in less than four minutes.

With this method you will:

  • Reduce analysis cycle time to less than four minutes with some columns, thus increasing your throughput and decreasing costs.
  • Save money on mobile phase preparation time and materials costs.
  • Achieve better reproducibility due to simplified preparation and operating procedures.

The method has the following characteristics:

  • Uses a simple and inexpensive mobile phase that does not require buffers. You have two options to choose from.
  • Uses commercially available columns from reputable manufacturers. You have four options from two different manufacturers.
  • Can be used on any modern HPLC equipped with an absorbance detector, although wavelength switching or multi-channel detectors (e.g., diode array) will improve sensitivity and selectivity. We will even give you three different detection options.
  • Is linear from 1 - 100 ug/mL (ppm). Lower concentrations can also be detected.
  • Has an analysis time of less than 4 minutes!
  • Is simple to use and operate.

Our method includes the following information:

  • Materials and Equipment
  • Preparation of Standards and Mobile Phase
  • Instrument Equilibration and Calibration
  • Options for column selection, mobile phase, and detector settings.
  • Analysis Conditions and Suggestions for Further Optimization
  • Sample Preparation, QC, and Calculations
  • Performance Data (see table below)
  % Relative Standard Deviation (%RSD)
Parameter Caffeine Sorbate Benzoate
Retention Time 0.09 % (n = 9) 0.08 % (n = 9) 0.09 % (n = 9)
Peak Area 0.30 % (n = 4) 0.31 % (n = 4) 0.17 % (n = 4)

Results matter!

These two chromatograms compare a standard mixture with Monster energy drink. Notice the good separation of sorbate and benzoate and an analysis time of less than four minutes, with no interferences.

Note: We have also used this method for Amp and Rock Star, with the same results.

Monster, Amp, and Rock Star are copyrighted products of their respective manufacturers. There is no relationship between these manufacturers and ACCTA, Inc.

Why Pay For a Method?

You will spend $49 of your time just doing a Google search. We know, we tried it! The top hits in the search are all less efficient and more expensive than our method.

We have done the work for you, and are offering the method details for less than it would cost to develop the method in your laboratory.

Our expertise is developing and optimizing methods. If you aren't in the business of method development, you would never be able to develop a rugged method like this one for under $1000. If you do method development, you will recognize the value in having the basic operating parameters already identified.

You can purchase the details of this method using one of the following options:

  • Purchase the method details and a license to use this method, with installation and training by your own staff.
    • Cost: $49, Delivery: electronic (pdf format).
    • Payment: Order on-line.
  • Purchase the method details and a license to use this method, with on-site training at your facility by our staff.
    • Cost: Call for quote, Delivery: one day of on-site installation and training.
    • Payment: Purchase Order/Check
  • Purchase the method details, a license to use this method, and method development services to adapt the method to your specific product(s).
    • Cost: to be determined based on your individual needs
    • Payment: Purchase Order/Check

Analysis of your samples in our laboratory is also possible. Please contact us for more information, or to receive one free analysis of your sample type.

Summary of License Agreement
Click here for complete details, which are also attached to the method.

  • This license allows you to use this analytical method in one laboratory. One laboratory is defined as a contiguous laboratory facility at a single site. Multiple laboratories at a single site may use the method only if they are engaged in the same analytical functions, and are separated solely for logistical purposes.
  • This Method may not be copied, distributed, or transmitted to other individuals or laboratories, except as required for regulatory and/or documentation purposes.
  • Any public presentation or publication that includes method details must cite the copyright holder (ACCTA, Inc.).
  • Derivative documents (SOPs, etc.), written by the purchaser, that incorporate the details of this method are covered under this License Agreement.
  • Verification and validation of Method performance in the Licensee's laboratory are the responsibility of the Licensee.


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