Rapid isolation with Sep-Pak C18 cartridges and wide-bore capillary gas chromatography of some butyrophenones

Summary A simple and rapid method for isolation of five butyrophenones with Sep-Pak C₁₈ cartridges from human samples, and their wide-bore capillary gas chromatography (GC), are presented. The GC was made by both flame ionization and electron capture detections. The drugs contained in alkaline samples were directly applied to the cartridges and eluted with chloroform/isopropanol (9:1). The recoveries with use of the cartridges were excellent for most drugs in both urine and plasma samples. We can recommend the Sep-Pak C₁₈ cartridges for isolation of butyrophenones because of simplicity and rapidity, and also wide-bore capillary GC because of high sensitivity and low decomposition of drugs during passage through the column.     

Rapid isolation with Sep-Pak C18 cartridges and wide-bore capillary gas chromatography of some barbiturates

A simple and rapid method for isolation of nine barbiturates with Sep-Pak C18 cartridges from human urine, plasma and whole blood, is presented; the detection of drugs was made by wide-bore capillary gas chromatography (GC) with flame ionization. The drug-containing samples, after mixing with dilute acid solution, were directly applied to the cartridges and eluted with either chloroform/methanol (9:1) or acetonitrile. Separation of the nine drugs was satisfactory with use of an intermediately polar HP-17 capillary column. Recoveries of most compounds were excellent for both chloroform/methanol and acetonitrile as elution solvents. However, backgrounds were cleaner and evaporation time was much shorter for the chloroform/methanol system. The present isolation method with use of Sep-Pak C18 cartridges and wide-bore capillary GC seem very useful in the fields of forensic chemistry, clinical toxicology and clinical pharmacology.     

Simple and sensitive detection of phencyclidine in body fluids by gas chromatography with surface ionization detection

Phencyclidine (PCP) can be detected in body fluids with very high sensitivity by gas chromatography (GC) with surface ionization detection (SID) using pethidine as internal standard. PCP was extracted with Sep-Pak C₁₈ cartridges from whole blood and urine samples, which gave clean extracts. The calibration curve for spiked whole blood was linear in the range 1.25–20 ng/ml. The detection limit of PCP was approximately 15 pg on-column (0.75 ng/ml sample), which was much lower than by GC-nitrogen phosphorus detection. The recovery of PCP and pethidine from spiked whole blood or urine samples was above 85%. This method seems very useful for the determination of PCP in forensic and clinical toxicology.     

Regional nodal staging with 18F-FDG PET-CT in non-small cell lung cancer: Additional diagnostic value of CT attenuation and dual-time-point imaging

Background

[Fluorine-18]-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET–CT) is widely performed in the regional nodal staging of non-small cell lung cancer (NSCLC). However, the uptake of ¹⁸F-FDG by tubercular granulomatous tissues may lead to false-positive diagnosis. This is of special concern in China, where tubercular granulomatous disease is epidemic. Herein, we evaluated the efficacy of an additional CT attenuation and a dual-time-point scan in determining the status of lymph nodes.

Methods

Eighty NSCLC patients underwent curative surgical resection after ¹⁸F-FDG PET–CT and separate breath-hold CT examinations. The initial images were analyzed by two methods. In method 1, nodal status was determined by ¹⁸F-FDG uptake only. In Method 2, nodal status was determined by ¹⁸F-FDG uptake associated with CT attenuation. For dual-time-point imaging, the retention index (RI) of benign and malignant nodal groups with positive uptake in the initial scan was examined.

Results

A total of 265 nodal groups were documented. On a per-nodal-group basis, the diagnostic sensitivity, specificity, and accuracy of Method 1 were 66.7%, 89.7%, and 85.3%, respectively, whereas those of Method 2 were 64.7%, 96.7%, and 90.6%, respectively. The improvement in diagnostic specificity and accuracy associated with the addition of CT attenuation in Method 2 as compared to Method 1 was statistically significant (p < 0.01). Thirty-nine nodal groups with positive uptake in the initial scan underwent dual-time-point imaging and the difference in the RI between benign and malignant groups showed no statistical significance (p > 0.05).

Conclusion

¹⁸F-FDG PET–CT has high diagnostic value for preoperative lymph-node (N) staging of NSCLC patients. We show that ¹⁸F-FDG uptake combined with CT attenuation improves the diagnostic specificity and accuracy of nodal diagnosis in NSCLC. For the lymph nodes with positive uptake in the initial scan, dual-time-point imaging has limited effect in differentiation.