Some studies have focused on finding genes that predispose the person to be dependent on marijuana, cocaine, or heroin by studying genes that control a persons dopamine and opioid receptors, but no conclusive findings were reported. Other researchers found a connection between dopamine receptor genes and dependency on a substance. A potential problem with this study was that alcohol is commonly used with another substance, so the results of the study may not have been caused by dependency on a single substance. This means that multiple substances may have been contributing to the results, but the researchers suggested that further research should be done.However, there are studies that have found evidence of the influence of genes on vulnerability to substance dependence. These studies often use genotype, or the genetic information found on a persons chromosomes, and phenotype, which consists of the visible features of a person, to look at genetic patterns. One study examined the phenotype and genotype of 1,858 participants from 893 families to look at differences in three nicotinic acetylcholine receptor genes found within these individuals. The experimenters found significant connections between receptor genes for nicotine and polysubstance dependence, which indicated that differences in these genes can create the risk of being dependent on multiple substances. Psychological
A 1989 study conducted by Khantzian and Treece found that nearly 60% of their opioid-dependent sample met criteria for an Axis II diagnosis. In the same study, 93% of the sample had a comorbid disorder, implying that the comorbid disorder plays some role in the addiction.
Preparation of hydrogels based on polyaspartic acid, in a variety of physical forms ranging from fiber to particle, can potentially enable facile separation of the chelated ions from a solution. Therefore, despite being weaker than EDTA, polyaspartic acid can still be regarded as a viable alternative due to these features as well as biocompatibility, and biodegradability. S,S-Ethylenediamine-N,N′-disuccinic acid (EDDS)
A structural isomer of EDTA, ethylenediamine-N,N′-disuccinic acid (EDDS) is readily biodegradable at high rate in its S,S form. Methylglycinediacetic acid (MGDA)
Trisodium dicarboxymethyl alaninate, also known as methylglycinediacetic acid (MGDA), has a high rate of biodegradation at over 68%, but unlike many other chelating agents can degrade without the assistance of adapted bacteria. Additionally, unlike EDDS or IDS, MGDA can withstand higher temperatures while maintaining a high stability as well as the entire pH range. MGDA has been shown to be an effective chelating agent, with a capacity for mobilization comparable with that of nitrilotriacetic acid (NTA), with application to water for industrial use and for the removal of calcium oxalate from urine from patients with kidney stones. Methods of detection and analysis
The most sensitive method of detecting and measuring EDTA in biological samples is selected reaction monitoring capillary electrophoresis mass spectrometry (SRM-CE/MS), which has a detection limit of 7.3 ng/mL in human plasma and a quantitation limit of 15 ng/mL. This method works with sample volumes as small as 7–8 nL.EDTA has also been measured in non-alcoholic beverages using high performance liquid chromatography (HPLC) at a level of 2.0 μg/mL.