Quantification of α-Acids in Fresh Hops by Reverse-Phase High-Performance Liquid Chromatography

Abstract

This publication describes a method for the quantification by high-performance liquid chromatography (HPLC) of resinous compounds known as α-acids found in freshly harvested, unprocessed hops. This method provides consistent, efficient, and accurate results as well as the theories and rationale involved in HPLC method development. A system of quality checks was utilized as well as the validation of numerous developmental variables. By starting with a theoretical approach in preparation, extraction, and instrumental techniques and then further developing these practices by experimentation, a reproducible method was developed. Following the validation, fresh cascade hops grown in Sonoma County were analyzed during the 2017 harvest season and found to be within the predicted range specific to this cultivar. This method encompasses the techniques necessary to analyze fresh or dried hops, considering variability between different laboratories.

Effects of pre‐analytical procedures on blood biomarkers for Alzheimer's pathophysiology, glial activation, and neurodegeneration

“…30 Blood Aβ has been measured using both ultrasensitive immunoassays 31,32 and mass spectrometry-based methods. 33,34 35,36 and increases more quickly than blood NfL and, after peaking, it rapidly decreases. Blood GFAP also increases in other neurodegenerative disease like AD, likely in response to Aβ pathology 23,32,37 and, particularly in frontotemporal dementia 20 due to progranulin (PGNR) mutations.…”

“…This release results in a primary (hours) and secondary (days) peaks in which the latter is predictive of neurological outcome 30 . Blood Aβ has been measured using both ultrasensitive immunoassays 31,32 and mass spectrometry‐based methods 33,34 . These studies have shown that blood Aβ42 and/or the Aβ42/Aβ40 ratio correlates with those in the CSF and with Aβ PET and can discriminate Aβ‐positive individuals from those who are Aβ‐negative.…”

Identification and determination α and β-acids from Columbus hops using Reverse Phase High Pressure Liquid Chromatography

“…However the retention time of the sample is slightly slower than the standard. A comparison of the retention times is presented in Table 1 The time consumed for the present method in identifying  and  acids is better than the results where the retention time of alpha acid is above 10 minutes and  acids is greater than 19 minutes [20]. In addition, the samples were quite well separated indicating that some impurities appeared and separated by retention time on the range of 1.1 -4.5 minutes.…”

“…This is due to the similarity of the hydrophobicity of humulone with adhumulone and lupulone with adlupulone. Only four chromatograms found, these are shown on Figure 1 [20]. The use of pH 2.8, which might reduce the variability in spacing and increase the resolution, considering that the two analytes have a pKa ranging from 4.25 to 5.93.…”

“…The use of pH 2.8, which might reduce the variability in spacing and increase the resolution, considering that the two analytes have a pKa ranging from 4.25 to 5.93. [20,21] On the separation of the Columbus hops samples, the results showed that the chromatogram had the same pattern as the standard pattern. However the retention time of the sample is slightly slower than the standard.…”