*3.5. Atomic Spectroscopy, Raman Spectrosocopy, Fluorescent Spectrosocopy*

Besides the above-mentioned spectrophotometric methods based on measuring molecular absorption and elastic scattering of optical radiation, spectroscopic techniques that utilize different optical phenomena are also used for milk analysis and quality control, though not so often.

In analytical chemistry, atomic spectroscopy is considered to be the most widespread method for elemental analysis; when applied to milk and dairy products it is mainly used for the determination of macroelements (Ca, P, Mg, K) and microelements (P, Fe, Zn, Se, Al, Cd, Cu, S), including toxic heavy metals (Cd, Pb). Various techniques are employed: atomic absorption spectroscopy with prior atomization [98], inductively coupled plasma atomic emission spectrophotometry [99,100].

Raman spectroscopy has long been used for the quality control and the quantitative analysis of powdered milk and baby formula and to screen samples adulterated with whey and melamine. It is a very capable and convenient method, because Raman spectra can be collected extremely fast, without any special sample preparation, and even from samples in glass and polymer packaging [101]. The main obstacle for the application of Raman analysis for liquid milk and other dairy products with high humidity is a weak signal from the main milk constituents on the background of very intensive water bands. Despite this problem modern chemometrics approaches have been successfully used for extracting from the Raman spectra of milk information about the concentrations of fat, proteins, lactose, antibiotics, and adulterants (melamine) [102]. Raman spectroscopy are even considered as a perspective on-line analytical method [103].

Molecular fluorescence spectroscopy is one of the most sensitive and highly selective spectroscopic methods, which can detect extremely low amount of chemical substances. In milk industry it is used for the determination of vitamins, fatty acids [104], residual amounts of antibiotics [105], and identification of different milk species in dairy products [106].
