The ratio of concentrations of D-aspartic acid and L-aspartic acid in dentin of 27 premoars of different ages was determined with chiral capillary column gas. chromatography. Acidic isopropanol and trifluoroacetic acid anhydride were derivative agents. The linear regression between the degree of racemization and age was established, r= 0. 9568, SD= 4. 5 years. This seems to be a new method which is more accurate and objective than others in age estimation with teeth.

A method for simultaneous isolation and clean-up pyrethroid insecticides (methothrin, fenpropathrin,cyhalothrin, permethrin, cypermethrin, fenvalerate and deltamethrin)with a solid phase extractionmethod (Sep-Pak C18 cartridge) from biological samples (human plasma and urine) is presented.The systematic separation of the insecticides was excellently performed by wide-bore capillary gaschromatography with flame ionization detection and temperature programming. The recoveries werebetween 81% and 93% for plasma, and 90% and 102% for urine. Mixing the samples with 70%methanol and eluting with chloroform demonstrated excellent adsorption on C18 and the best recoveries,respectively.

A new method of determination of COHb is reported in this paper by two- wavelength second-derivative spectrophotometry.Blood was diluted with a solution of THAM containing Na_2S_2O_4.The second-derivative spectrum was measured in the region of 500-600 nm and the derivative absorbance differerce ?Ax was deter mined at the wavelengths of 564 nm and 576 nm.Then the solution was satura- ted with CO gas.The second-derivative spectrum of COHb was measured in the same region.The derivative absorbance difference ?A_(100) was determined at the same wavelengths.The COHb in blood was calculated by the ratio of ?Ax to ?A_(100).The results of determination of COHb in standard blood samples were in good agreement with the theoretical values.