Aspects of Matrix Effects in Applications of Liquid Chromatography-mass Spectrometry to Catecholamine Analysis-a Review

Background: Recently, liquid chromatography based on tandem mass spectrometry (LC-MS/MS) has become an efficient tool in analyzes of many compounds in various biological matrices. However, as known by researchers, these biological matrices cause various interferences by suppressing (ion suppression) or increasing ionization (ion enhancement). Since this challenge was recognized in the 1990s, many studies have been published on it, and its causes have been reviewed countless times for various compounds. However, none of the current studies specifically addressed aspects of matrix effects that have to do with catecholamines. Discussion: This review will focus on these issues, critically discussing experiments and results of matrix effects in LC-MS/MS applications on catecholamine analysis in various biological matrices. Moreover, it can be guided on the performance of studies on matrix effects in LC-MS/MS procedures in bioanalytical systems. Conclusion: This article is useful for academics such as analytical chemists, pharmacologists and also members of the pharmaceutical industry working on catecholamines and liquid chromatography-mass spectrometry.

L-DOPA therapy interferes with urine catecholamine analysis in children with suspected neuroblastoma: a case series

Neuroblastoma is the most common solid extracranial malignancy diagnosed in childhood. Clinical presentation is variable, and metastatic disease is common at diagnosis. Analyses of urinary catecholamines and their metabolites are commonly requested as a first-line investigation when clinical suspicion exists. Levodopa (L-Dopa) therapy is utilized as a treatment for a number of disorders in childhood, including Dopa-responsive dystonia. Neuroblastoma may mimic some of the clinical features of this disorder. L-Dopa can interfere with analysis of urinary catecholamines and their metabolites and complicate the interpretation of results. We present the cases of three children who were prescribed L-dopa at the time of analysis of urinary catecholamines and metabolites as a screen for neuroblastoma, but who did not have the disease. Comparison of their results with those from cases with true neuroblastoma reveal that it is impossible to reliably distinguish true neuroblastoma from L-Dopa therapy using these tests. We recommend that patients should be off L-dopa therapy, if possible when these tests are performed. These cases illustrate the importance of providing clinical details and drug history to the laboratory in order to avoid diagnostic confusion.

Acupuncture Improves Sleep Conditions of Minipigs Representing Diurnal Animals through an Anatomically Similar Point to the Acupoint (GV20) Effective for Humans

Acupuncture, an alternative medicine, has been widely applied for people with sleep disturbances; therefore, the effects should be evaluated objectively. Micro-minipigs (MMPigs), the smallest miniature pigs for animal experiments, were used. Acupuncture was performed at two different points: Dafengmen is located on the head and is an anatomically similar point to human-Baihui (GV20), an effective acupoint for sleep disturbances in humans; pig-Baihui is on the back. The procedure was performed as follows: shallow, within 5 mm depth for several seconds; deep, 10–20 mm depth for 20 min. The sleep conditions were evaluated by actigraph, and the amount of catecholamine in pooled urine after acupuncture treatment. MMPigs with deep acupuncture at Dafengmen showed significantly efficient values on actigraph and catecholamine analysis as compared with untreated MMPigs. The effective acupoint for sleep conditions in the porcine model is at an anatomically similar point to humans, rather than the point determined by traditional Chinese medicine.