tract of 1 ml of the same specimen to which 5 pg of meperidine hydrochloride was added. Note the low background contributed by normally occurring extractives a t 425 nm and 440 nm. The limit of detectability for the compound when extracted from urine or plasma is around 300 ng per milliliter. Recovery of meperidine added to urine and plasma lies in the vicinity of 65 %. The method has been applied successfully to the analysis of human tissues obtained at autopsy from decedents who had been administered the drug prior to death. In these instances, the compound was isolated from the biologic matrix by the alkaline-ether extraction procedure described by Goldbaum and Domanski (1). The method fails in the presence of quinine, quinidine, and methapyrilene, all of which give rise to products that fluoresce in the 425-nm to 440-nm region. Phenothiazines, benzodiazepines, dibenzazepines, and opiates d o not interfere.
RECEIVED for review March 19, 1970. Accepted May 8, 1970. (1) L. R. Goldbaum and T. J. Domanski in “Progress in Chemical Toxicology,” Volume 2, A. Stolman, Ed., Academic Press, New York, 1965, p 222.
Figure 1. Uncorrected excitation ( A ) and emission ( B ) spectra for meperidine fluorophore (b)
Correction Analysis of Polyimide Dielectric Coatings Using Attenuated Total Reflectance I n this article by R. J. McGowan [ANAL.CHEM., 41, 2074 (1969)l there are errors both in Table I and Figure 3. The correct versions appear below. Table I. Relationship Between Curing Time and Per Cent Absorption Absorbance Spectrum Curing @ 12.5 no. time in mins micron Crazing 0.15 V. severe 2 15 Moderate 3 30 0.22 Slight 4 45 0.24 V. slight 5 60 0.37
-
L
425 440
425 440
NANOMETERS
Figure 2. Fluorescence spectra of extracts from ( A ) urine negative for meperidine and ( B ) urine containing 5 pg meperidine per milliliter Intensity of emission is enhanced steadily with increasing incubation time up to a maximum between 8 and 12 minutes. Further heating results in substantial decrements of fluorescence. Figure 2 shows the emission spectra of ( A ) the extract of 1 ml of a urine which was negative for the drug, and ( B ) the ex942
rn
ANALYTICAL CHEMISTRY, VOL. 42, NO. 8, JULY 1970
-02
11
Spectrum No.
A bsorbonce
2. Cured 15 M i n
015
3. Cured 3 0 M i n
0.22
4. Cured 45 M i n
0.24
5. Cured 60 Min
0.37
12 13 14 MICRONS
Figure 3. ATR spectra of samples showing increasing absorbance with curing time
