Earticle

화학사고 현장에서 운용하도록 개발된 휴대용 GC/MS의 적정 시료 주입방식 연구 및 장비의 분석방식별 성능평가를 실시하였다. 사고대비물질 69종 중 4종(methyl chloride, vinyl chloride, benzene, toluene)의 대상물질을 선정하였고, 성능평가용 표준시료는 한국표준과학원에서 제조한 인증표준물질(CRM)을 사용하였다. 연구 결과, 1) 3가지(실린더, 백, 캐니스터)의 시료주입방식 중 백(bag) 주입방법이 가장 적합한 주입방법으로 판단되었다. 백(bag)의 재질이나 용량은 결과에 큰 영향을 미치지는 않았다. 도입 시료의 적절한 purge time은 Loop method와 Tenax method 모두 2분에서 가장 좋은 재현성을 보였다. 2) 휴대용 GC/MS에서 채택하고 있는 3가지 분석방식(sample loop, tenax concentration, carbopack concentration method)에 대한 대상물질의 재현성, 검출한계, 직선성 등의 성능평가 실시 결과 benzene, toluene과 같이 비교적 분자량이 큰 화합물은 Tenax 흡착관에, methyl chloride, vinyl chloride와 같이 분자량이 작고 휘발성이 큰 화합물은 carbopack 흡착관에 농축 분석하는 것이 더욱 재현성 있는 결과를 얻을 수 있었다.

In this study, we evaluated the method performance and the optimum sample injection method of the portable GC/MS(HAPSITE) which were designed to operate on scene of chemical accidents. Chemicals used for performance test were vinyl chloride(VC), methyl chloride(MC), benzene(Bz), toluene(Tol). CRM(Certified Reference Material) Manufactured by KRISS(Korea Research Institute of Standards and Science) was used as the standard gas. The results showed that 1) Among three sample injection methods(Cylinder, Silico canister, and Bag), bag was identified as the most appropriate sample injection method. Bag material and capacity did not significantly affect the results. The most ideal reproducibility occurred at the 2-minute point of the purge time in the loop and tenax methods. 2) Performance evaluation of HAPSITE was conducted. Evaluation items were reproducibility, linearity, method detection limit, etc. Tenax concentration method was appropriate for larger molecules and Carbopack concentration method was suitable for smaller molecules.

Pseudoephedrine (PSE)은 methamphetamine의 불법합성에 중요한 화학적 전구체 중의 하나로 이에 대한 신속하고 용이한 동정과 반정량을 목적으로 하는 방법의 개발을 위한 예비실험을 실행하였다.TLC상에서 PSE와 유도체화 시약을 직접적(in situ, co-spot)으로 반응시켜서 생성된 유도체를 확인하여 검출한계를 결정하고 이들에 대한 이미지를 이미지 분석 프로그램으로 재현성과 직진성에 대해 분석하 여 반정량적인 분석에 적합한지 평가하였다. PSE의 칼람 분리 전(pre-column)에 행하는 직접적인(co-spot) 유도체화 반응성을 평가하고자 PSE를 실리카 젤(SiO2) TLC 상에서 3종의 검출특징이 다른 유도체화 시약 9-fluorenylmethyl chloroformate (FMOC-Cl), dansyl chloride (Dansyl-Cl) 및 dabsyl chloride (Dabsyl-Cl)와 각 각 반응시켰다. 유도체화 반응 생성물을 UV 혹은 가시광선에서 육안으로 확인한 후, TLC 이미지 분석을 통하여 생성 spot(s)에 대한 반응의 재현성을 평가하고, 추가적으로 반 정량분석을 위한 직선성을 평가하였다. 모든 유도체화 시약들은 TLC상에서 PSE와 반응하여 가시광선 혹은 UV-active한 작용기를 함유한 유도체를 생성하였으며 각 시약에 따른 PSE와의 반응성의 차이가 관찰되었다. PSE의 검출한계 (Limit of detection, LOD, 2 μL per spot, mg/mL)농도는 FMOC-Cl과(상온에서 노출하여 10분간 반응), Dansyl-Cl 사용 시(반응 spots들을 유리판으로 덮은 상태에서 70 oC로 가열) 0.001~0.005 mg/mL의 농도 구간에서 양호하였으나 Dabsyl-Cl의 경우에는 가열을 하였음에도 0.25 mg/mL의 높은 농도에서 검출이 가능하였다. 반응의 재현성(RSD, 평균치, %)은 FMOC-Cl의 사용 시 PSE 0.5 mg/mL의 농도에서 2.14 ~ 2.27%로 양호하였으나 저 농도 0.1 mg/mL에서는 5.87 ~ 6.20%으로 변동이 심하였고, Dansyl-Cl의 경우 에는 두 가지 농도(0.5 및 0.05 mg/mL)에서 4.63 ~ 5.61%로 역시 변동이 심하였다. 반응의 직선성(linearity,R2) 평가에서 PSE의 높은 농도구간(0.1 ~ 1.0 mg/mL)에서는 FMOC-Cl과 Dansyl-Cl시약 모두 PSE의 농도에 따른 생성 유도체의 면적과의 상관관계가 0.96 ~ 0.98로 비교적 양호한 상관성을 보였으나, PSE의 검출한계 농도에서 1.0 mg/mL의 농도구간에서는 0.90 ~ 0.92로 감소하였다. 현재의 방법으로 세 가지의 유도체들이 다소 낮은 재현성으로 생성이 되었으며, PSE에대한 검출한계 농도는 유도체화 이전의 검출한계의 농도보다 160 ~ 1000배가량 낮추었으나, 본방법의 PSE에 대한 반정량적인 사용을 위한 방법으로서의 유효성을 보이기 위해서는 사용시약의 다양한 농도변화, 다른 반응용매 사용에 의한 영향, 반응온도의 변화 등에 대한 PSE의 다양한 농도에서의 유도체화 반응의 재현성을 높이기위한 추가적인 실험결과가 필요하다.

Pseudoephedrine (PSE) is the critical chemical precursor involved in the illegal production ofmethamphetamine. A preliminary test for the rapid and easy identification and semi-quantitative determinationof PSE was performed. PSE derivatives generated from direct reaction (in situ ,co-spot) of PSE with derivatizing reagents were identified and used to determine the LOD. The TLC images were analyzed with densitometric image analysis programs to determine the repeatability and linearity of derivatization reaction for a potential semi-quantitative analysis. PSE was reacted in situ (co-spot) to evaluate their derivatization reactivity in the pre-column mode on a silica gel TLC plate with FMOC-Cl, Dansyl-Cl or Dabsyl-Cl as derivatizing reagents. The derivatized products were identified under naked eyes with or without UV light and the TLC image analysis of corresponding spots was performed using the densitometric image analysis for the semi-quantitative evaluation. All the derivatizing reagents generated compounds containing strongly visible or UV-absorbing FMOC-, Dansyl- and Dabsyl- groups on the TLC plate after reacting with PSE. However, a different reactivity of PSE with the reagents was observed. In the experiment using FMOC-Cl (reaction spots exposed with air at room temperature for 10 min.) and Dansyl-Cl (reaction spots covered with glass plate while heated at 70 oC for 10 min.), the LODs (Limit of detection, 2 μL/spot, mg/mL) of PSE was in the low concentration range of 0.001 ~ 0.005, but the higher LOD concentration of 0.25 was found when Dabsyl-Cl was used even when the reaction spots were covered and heated. The RSD value (average, %) to test the repeatability of the derivatization reaction for PSE (0.5 mg/mL) was in the range of 2.14 ~ 2.27% when FMOC-Cl used. But a high RSD value range of 5.87 ~ 6.20% was shown at the low concentration (0.1 mg/mL) of PSE. Also at two concentrations (0.5 mg/mL and 0.05 mg/mL) of PSE with Dansyl-Cl, the high RSD value range of 4.63 ~ 5.61% was found. In the test of the linearity (R2) of the derivatization reaction at a high concentration range (0.1 ~ 1.0 mg/mL) of PSE with FMOC-Cl and Dansyl-Cl, a relatively good correlation was shown to be in the range of 0.96 ~ 0.98 between the areas of spots of generated derivatives and concentration of PSE. However, the R2 values calculated from the concentration of the LOD of PSE up to a high concentration (1mg/mL) of PSE was dropped into the range of 0.90 ~ 0.92. The current method generated three derivatives with rather low repeatability and provided a way to improve the LOD of PSE to 160 ~ 1000 times compared to the TLC method of underivatized PSE. To demonstrate the validity of the current method to be used for a semi-quantitative analysis of PSE by showing the high repeatability of a derivatization reaction at various concentration of PSE, additional experimental results are required such as the various changes of the concentration of derivatization reagents, the usage of other reaction solvent, changes of reaction temperature, etc.

The purity methods to determine LOD/LOQ using standard deviation of the residual, intercept and blank by IUPAC and ACS describe many of the pitfalls and pose significant challenges to analytical chemists. Therefore, the aim of this study is the development of the simple, easy, convenient and statistically significant method to determine LOD in quantitative analysis of organic solvents by GC. The new approaching method by linearization in the given concentration range used coefficient of variation ; ${\sigma}_{n-1}$/S(standard deviation, ${\sigma}_{n-1}$ and average, S) of sensitivity(Response/concentration). The comparison of results among the purity methods(IUPAC and ACS) and the linearization have been fulfilled the F-test for standard deviations and t-test for LOD range values. The results of F-test and t-test are satisfied within 95 % confidence level, respectably. The LOD values determined by the new procedure are n-Hexane 0.0116 mg/$m^3$, Toluene 0.0807 mg/$m^3$, and o-Xylene 0.0494 mg/$m^3$. Because the standard deviation of the residual, intercept and blank and the slope of calibration curve are not calculated and the new approaching method use the coefficient of variation of sensitivity by linearization, this new method is simple, easy, convenient and statistically significant. In future, many chemical analysts will expect to applicate and routinely use this method in the all quantitative analysis.