fabric softeners also make them useful in hair conditioners and shampoos. The idea was pioneered by Henkel with a 1984 patent. Examples include cetrimonium chloride and behentrimonium chloride. Plant growth retardants Cycocel (chlormequat chloride) reduces plant height by inhibiting the production of gibberellins, the primary plant hormones responsible for cell elongation. Therefore, their effects are primarily on stem, petiole and flower stalk tissues. Lesser effects are seen in reductions of leaf expansion, resulting in thicker leaves with darker green color. Natural occurrence Glycine betaine, found in osmolytes, stabilizes osmotic pressure in cells. Choline is a precursor for the neurotransmitter acetylcholine. Choline is also a constituent of lecithin, which is present in many plants and animal organs. It is found in phospholipids. For example, phosphatidylcholines, a major component of biological membranes, are a member of the lecithin group of fatty substances in animal and plant tissues. Carnitine participates in the beta-oxidation of fatty acids. Health effects Quaternary ammonium compounds can display a range of health effects, amongst which are mild skin and respiratory irritation up to severe caustic burns on skin and the gastrointestinal wall (depending on concentration), gastrointestinal symptoms (e.g., nausea and vomiting), coma, convulsions, hypotension and death. They are thought to be the chemical group responsible for anaphylactic reactions that occur with use of neuromuscular blocking drugs during general anaesthesia in surgery. Quaternium-15 is the single most often found cause of allergic contact dermatitis of the hands (16.5% in 959 cases). Possible reproductive effects in laboratory animals Quaternary ammonium-based disinfectants (Virex and Quatricide) were tentatively identified as the most probable cause of jumps in birth defects and fertility problems in caged lab mice. The quat ingredients in the disinfectants include alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC). A similar link was tentatively identified in nurses. The studies contradict earlier toxicology data reviewed by the U.S. Environmental Protection Agency (U.S. EPA) and the EU Commission. Quantification The quantification of quaternary ammonium compounds in environmental and biological samples is problematic using conventional chromatography techniques because the compounds are highly soluble in water. Analysis by liquid chromatography coupled tandem mass spectrometry has found that they follow an exception rule. Under standard electrospray ionization (ESI) conditions, mono- and di-quaternary ammonium compounds form molecular ions with the formula of rather than . Formation of is observed for di-quaternary ammonium compounds (like diquat) as precursor ion and as product ion