Re: What is the exact composition of sweat under normal circumstances?

The composition of sweat can vary greatly between different people, and is 
influenced by emotional state, diet, exercise and a variety of hereditary 
factors.  For example, you may have noticed an oniony or garlicky odor on your 
skin after consuming those foods.

Here is a paragraph on sweat composition I copied from the online Encyclopedia 
Britanica:

The composition of sweat is similar to that of plasma except that sweat does not
contain proteins. After secretion, the fluid moves through the sweat duct, where 
salt and water are reabsorbed. The exact mechanism of sweat secretion is not 
known. It appears that sweat is a filtrate of plasma that contains 
electrolytes(such as potassium, sodium, and chloride) and metabolic wastes (like 
urea and lactic acid).Because sweat resembles a filtrate of plasma, 
water-soluble chemicals, like some drugs and metal ions, are found in sweat. 
Sweat is not a major route of excretion of chemicals, however.

(Plasma is the liquid part of blood after the cells are removed)

Erin