Liu R H, Edwards C, Baugh L D, Weng J L, Fyfe M J, Walia A S
Graduate Program in Forensic Science, University of Alabama at Birmingham 35294.
J Anal Toxicol. 1994 Mar-Apr;18(2):65-70. doi: 10.1093/jat/18.2.65.
Apparent analyte concentration (equivalent of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid [9-THC-COOH]) obtained by radioimmunoassay (RIA) for cannabinoids using reagents manufactured at four different periods (from the same manufacturer) and specific 9-THC-COOH concentration as determined by GC/MS are examined for the significance of their correlation. The resulting regression equations are then used to estimate the apparent RIA analyte concentrations of reagents manufactured at different time periods that are equivalent to a specific 9-THC-COOH concentration. Correlation coefficients of the regression analysis improve from approximately 0.4 to 0.7 in parallel with the increasing reagent specificity. The apparent RIA analyte concentrations that correspond to 15 ng/mL 9-THC-COOH decrease from about 110 to 50 ng/mL again in parallel with the increasing reagent specificity. These findings empirically demonstrate that reagent specificity is the determining factor of the resulting apparent RIA analyte concentration when testing samples that contain 9-THC-COOH and other metabolites (derived from marijuana exposure). Thus, if the 9-THC-COOH concentration as determined by GC/MS is of primary concern, the initial test cutoff concentration should be adjusted in accordance with the specificity of the reagent used.
采用放射免疫分析法（RIA）对大麻素进行检测时，使用在四个不同时期（同一制造商生产）制造的试剂获得的表观分析物浓度（相当于11-去甲-Δ⁹-四氢大麻酚-9-羧酸[9-THC-COOH]），并将其与通过气相色谱/质谱联用仪（GC/MS）测定的特定9-THC-COOH浓度进行相关性显著性检验。然后使用所得的回归方程来估算在不同时期制造的、与特定9-THC-COOH浓度相当的试剂的表观RIA分析物浓度。随着试剂特异性的增加，回归分析的相关系数从约0.4提高到0.7。与15 ng/mL 9-THC-COOH相对应的表观RIA分析物浓度也随着试剂特异性的增加而从约110 ng/mL降至50 ng/mL。这些发现从经验上证明，在检测含有9-THC-COOH和其他代谢物（源自大麻暴露）的样本时，试剂特异性是导致RIA分析物表观浓度的决定因素。因此，如果主要关注GC/MS测定的9-THC-COOH浓度，则应根据所用试剂的特异性调整初始检测临界浓度。
