• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.189-192
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• 2009

Purpose: Autopipetting system is an efficient automated equipment pipetting patient samples and reagents for rapid and accurate test. However, it can cause carryover between high concentration sample and low concentration sample. We evaluated carryover contamination of TECAN freedom Evo 100 autopipetting system. Materials and Method: We studied carryover contamination of $\alpha$-fetoprotein (AFP) and carcinoembryonic antigen (CEA) test on TECAN freedom Evo 100 autopipetting system. Very low concentration control samples were pipetted for comparison to the contaminated very low concentration samples. Then, The contaminated very low concentration samples were pipetted following the high concentration samples were pipetted alternately. The difference of low concentration samples represents carryover. The target value to decide carryover was 1ppm (parts per million). Results: For AFP, the mean values of the uncontaminated control samples and the contaminated samples were less than 0.6 IU/mL (the l imit of detection (LoD)). Carryover did not occur even though the high concentration sample which value was 650000 IU/mL. For CEA, the values of the low concentration control samples and the contaminated samples were less than 0.2 ng/mL (LoD). Carryover did not occur even though the high concentration sample which value was 65,000 ng/mL. Conclusions: Sample carryover was not found on TECAN freedom Evo 100 autopipetting system for AFP, CEA. However, carryover is a potential problem with automated instruments and robotic pipetting systems. Therefore, Clinical laboratories must periodically verify carryover contamination for the accurate and confidential test results.

• Environmental and Resource Economics Review
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• v.32 no.3
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• pp.149-166
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• 2023

The emissions trading system, introduced to reduce greenhouse gas emissions, experienced a sharp increase in emission allowance prices during the second plan period (2018-2020), which led to an increase in the demand for smooth supply and demand of emission allowances, while suppliers anticipating a shortage of emission allowances in the future did not participate in trading. Therefore, the authority temporarily revised the guidelines to ensure that the amount of allowances carried forward is proportional to the trading volume as a market stabilization measure. Through an optimization process using a dynamic nonlinear mathematical model, this paper analyzes the impact of the government's intervention on the carryover policy on GHG emission reductions and emission allowance market prices. According to the simulation analysis results, banking regulations could cause a decline in prices during the regulation period, even though the initial policy was predicted to be adopted.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.190-196
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• 2010

Purpose: This study was undertaken to investigate the feasibility of using automated liquid-handling systems equipped with reusable fixed tips in Radioimmunoassays and to demonstrate that the use of an automated pipetting instrument can decrease in the typical daily workload. Materials and Methods: The precisions of the automated pipettor and the manual pipettor were determined gravimetrically (n=30). A total of 30 specimens for HBs Ag were repeatedly pipetted (three replicates) with the automated pipettor and then retested. PSA samples were simultaneously pipetted with either the automated pipettor or the manual pipettor and then analyzed (n=40). Sample carryover test assessed for CA19-9, AFP and HCG when the automated pipettor was used. Pipetting speed of the automated pipettor and the manual pipettor were compared by evaluation of each workload. Results: The precisions coefficients of variation (CV) were 2.1% for the automated pipettor and 1.6% for manual pipettor. The mean cpm and CV for each group of replicates were 41,203 cpm and 3.7% for HBs Ag positive specimens, and 99 cpm and 7.9% for HBs Ag negative specimens, respectively. PSA results showed no significant differences between automated pipettor and manual pipettor (p=0.15, r=0.999). Carryover for CA19-9, AFP and HCG analytes was <0.1 ppm or below the assay limit of detection. Pipetting speed was significantly improved by using the automated instrument. Conclusion: There was no evidence that the use of an automated pipettor adversely affected any of the performance characteristics of the assay. Indeed, routine use of the Tecan automated pipettor has resulted in a decrease in the typical daily workload.

• Analytical Science and Technology
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• v.34 no.6
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• pp.259-266
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• 2021

Cannabis (Marijuana) is one of the most widely used drugs in the world, and its distribution has been controlled in South Korea since 1976. Identification of 11-nor-Δ⁹-carboxy-tetrahydrocannabinol (THCCOOH) in urine can provide important proof of cannabis use, and it is considered scientific evidence in the forensic field. In this study, we describe a simultaneous quantitative method for identifying THCCOOH and THCCOOH-glucuronide in urine, using simple liquid-liquid extraction (LLE), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). THCCOOH-D₃ and THCCOOH-glucuronide-D₃ were used as internal standards. Validation results of the matrix effect, as well as recovery, linearity, precision, accuracy, process efficiency, and stability were all satisfactory. No carryover, endogenous or exogenous interferences were observed. The limit of detection (LOD) of THCCOOH and THCCOOH-glucuronide were 0.3 and 0.2 ng/mL, respectively. The developed method was applied to 28 authentic human urine samples that tested positive in immunoassay screening and gas chromatography/mass spectrometry (GC/MS) tests. The ranges of concentrations of THCCOOH and THCCOOH-glucuronide in the samples were less than LOQ~266.90 ng/mL and 6.43~2133.03 ng/mL, respectively. The concentrations of THCCOOH-glucuronide were higher than those of THCCOOH in all samples. This method can be effectively and successfully applied for the confirmation of cannabinoid use in human urine samples in the forensic field.