Hi,
I am analyzing the content of anionic surfactant: sodium lauryl sulfate (SLS) in commercial detergents using HPLC-RID/refractive index detector.
I used column Agilent Zorbax Eclipse XDB C-18 (4.6 x 250mm, 5 μm). I had been trying to follow below method. It worked well with my SLS standard.
However when I injected my sample (laundry detergent containing around 2% SLS, linear alkylbenzene sulfonate, and typical detergent material like sodium carbonate, etc), the peak shown in expected retention time (RT=7.1 min) was not in good shape. It seems like it had merged with another peak (RT=7.2 min) because the peak area was more than doubled (I knew the SLS content in sample because I had analyzed it using different method).
I wonder if anyone has any suggestion about my HPLC results.
Thank you in advance.
Hi Agnes.
Do you know how is the composition of your standard Sodium Lauryl Sulfate? Did you have access to Certificate of Analysis? I believe the difference between standard and sample is happening because Sodium Lauryl Sulfate is a mixture of compounds with different organic chain, and in your sample you don't solve these compound in chromatographic method. Try use the same analysis in a column with lower particle size, this could help you.
Marcos Steola thank you for your suggestion. Yes I know the composition of my standard SLS, it is 70% C-12. Meanwhile, SLS in my sample should be around 65% C-12. Unfortunately, I don't have lower particle size column that's why the thing I've been doing is trying to change the parameters like mobile phase composition, column temperature, and so on.
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