Insulin: A review of analytical methods
Insulin is an important polypeptide hormone that regulates carbohydrate metabolism. Abnormal level of insulin is associated with diabetes mellitus characterized by chronic hyperglycemia. Therefore, reliable quantification of insulin is important for clinical purpose such as diabetes diagnosis and treatment. Nowadays, immunoassays and chromatographic assays are the primary methods developed for insulin analysis. In this review, we have summarized the principles, sensitivity, linearity range, and recovery of each method as well as their advantages and limitations of the most prevalent methods. Generally, immunoassays including enzyme-linked immunosorbent assay (ELISA), chemiluminescence immunoassay (CLIA), radioimmunoassay (RIA) and on-chip immunoassay have a good selectivity of insulin with less interferences and high throughput. Chromatographic assays including high performance liquid chromatography coupled with ultraviolet detection (HPLC-UV), micellar electrokinetic capillary chromatography (MECC), liquid chromatography with tandem mass spectrometry (LC-MS/MS) have advances in high sensitivity and capability of simultaneous determination of insulin and its analogues.