Determination of paraquat in tissue using ion-pair chromatography in conjunction with spectrophotometry

Homogenized tissue was deproteinized with sulfuric acid. Paraquat in the supernatant was quantificated directly with the dithionite reagent (step 1) or concentrated by the XAD-2 column chromatographic technique before paraquat determination (step 2). Tissue paraquat levels in the range of 0.01-75 mg/kg could be quantificated by second-derivative or zero-order spectroscopy using 2.5 g of tissues. The sensitivity could be increased tenfold by using 25 g of tissue samples. The coefficients of variation of within-run and day-to-day precisions of spiked paraquat in tissue homogenates were below 5% at concentrations of 10.0, 1.0 and 0.1 mg/kg, respectively. The recoveries of the spiked paraquat in tissues ranging from 0.1-10 mg/kg were 91% by step 1 and 74% by step 2. Using these simple methods, steps 1 and 2, the paraquat concentrations in the psoas muscle, liver, lung and kidneys of a swine dosed with 0.16 g/kg of paraquat were investigated. The results were in close agreement with those of the TCA deproteinization method followed by cation-resin column chromatography. The proposed method offers the advantages of simplicity, rapidity, reasonable sensitivity and a wide range of concentrations.     

气相色谱-串联质谱法分析尿和血中除草剂百草枯

目的建立尿和血中百草枯的离子交换固相萃取-气相色谱-串联质谱分析方法。方法尿样加内标乙基百草枯,用732阳离子交换树脂提取;血样加内标乙基百草枯,用三氯乙酸凝聚蛋白质后取上清液用732阳离子交换树脂提取。提取物用硼氢化钠在水溶液中碱性条件下还原,还原物用有机溶剂提取进行气相色谱-串联质谱法分析。结果尿和血中百草枯的提取率分别为76％和74％,检测限分别为2ng／mL和10ng／mL,尿添加百草枯100ng／mL和血添加百草枯500ng／mL水平的回收率分别为99．6±5．6％和99．3±7．6％（Mean±CV）。结论本文建立的分析方法灵敏度高,能够满足中毒致死案件检验及临床毒物检验的需要。     

Release of tissue paraquat into formalin solution during fixation

Formalin-fixed tissues and formalin solutions are among the most frequently found materials in pathology and forensic science laboratories. However, these materials are seldom used for the identification of poisons for forensic toxicology purposes. In this study, the possibility that paraquat may be released from formalin-fixed tissues during the fixation process was investigated. However, because of the interference of formaldehyde on the reduction of paraquat with dithionite reagent, paraquat in formalin solutions was treated with ion-pair column chromatography and then determined by measuring the derivative spectrum of reduced paraquat. The results show that the interference of formalin on paraquat determination has been eliminated by the proposed method. Furthermore, a study on the formalin solutions of fixed organs in cases with suspected paraquat intoxication revealed that portions of tissue paraquat had been released into formalin during the fixation process. Moreover, the paraquat levels in formalin increased with increased storage time. Therefore, these data suggest that the combined concentrations of paraquat in the formalin-fixed tissues and formalin solutions might reflect more reliably the total paraquat in the postmortem tissues. This investigation could be of value to the forensic toxicologist, especially in cases in which no fresh tissue samples are available for analysis.     

The differential elution of drugs from XAD-2 resin.

Biological fluids and tissue extracts prepared according to a previously published method were passed through a column of Amberlite XAD-2 resin for removal of drugs. The differential elution of the adsorbed drugs from the resin was performed by sequential elution of the drugs in four steps. The column was first washed with 30 ml of 0.05M sodium acetate buffer, pH 4.55. Drugs exhibiting acidic or neutral characteristics were then eluted from the column with 100 ml of chloroform in 20-ml aliquots. The column was then washed with 30 ml of 0.1M potassium carbonate, which was discarded. Drugs exhibiting basic characteristics were then eluted from the column with 100 ml of chloroform:isopropanol (3:1) in 20-ml aliquots. Sensitivity of drug detection with this method by thin-layer chromatography was 0.5 mug/ml in a 10-ml sample for nearly all drugs tested.     

Spectra interference between diquat and paraquat by second derivative spectrophotometry

A rapid and accurate method, combining solid-phase extraction and second-order derivative spectrophotomety approaches, is developed for the simultaneous determination of diquat (DQ) and paraquat (PQ) in blood, tissue and urine samples. Supernatant resulting from the precipitation of protein (with trichloroacetic acid) in plasma and tissue or Amberlite IRA-401 resin treated urine are passed through a mini-column packed with Wakogel gel (Silica gel). Analytes are then eluted with a non-organic solvent, 0.2mol/l HCl solution containing 2mol/l NH(4)Cl. UV spectrum of the eluent in 220-350nm range provides effective screen to detect the presence of DQ and/or PQ. In the presence of DQ or PQ alone, the analyte present is quantitated by conventional zero- or second-order derivative spectrophotometry. The calibration curve in the 0.1-5.0mg/l range for either analyte obeys Beer's law. When both DQ and PQ are present, their concentrations are determined by the peak amplitudes of their respective second-derivative spectra after the addition of alkaline dithionite reagent. Interference is negligible when the DQ/PQ concentration ratio is within the 5.0-0.2 range.Using a 2-ml of sample size, the detection limits for DQ and PQ in plasma are 0.02 and 0.005mg/l. The corresponding detection limits for urine samples (10ml sample size) are 0.004 and 0.001mg/l. Recoveries of DQ and PQ in triplicate plasma and urine samples spiked with 0.5mg/l of analytes are 93 and 85%. The precision of the proposed method resulting from triplicate study of spiked urine samples varies from 3.2 to 4.6% at 0.5mg/l of DQ and PQ, respectively.     

Detection of drugs using XAD-2 resin. III:A routine screening procedure for bile

The ability of bile to concentrate drugs and metabolites coupled with its general availability make it suitable for analysis and often the fluid of choice in postmorten cases requiring drug screening. Bile (5 to 10 ml) was diluted with water, sulfuric acid was added, and the mixture was autoclaved. The precipitated bile salts were easily removed by filtration and the filtrate (pH adjusted to 8.0 to 8.5) extracted with XAD-2 resin. Drugs were eluted with a mixture of ethyl acetate/1,2-dichloroethane and analyzed with thin-layer chromatography. Varying the dilution of bile improved the recovery of morphine, codeine, methadone, amobarbital, and phenobarbital. Excessive dilution, however, caused a washing phenomenon and reduced recovery of some drugs, as shown with morphine and codeine. The procedure described is useful for the rapid screening of bile specimens for drugs.     

Determination of paraquat in raw and formalin-fixed tissues by electron spin resonance (ESR) spectroscopy

ESR method was applied to determine paraquat levels in fresh and formalin-fixed tissues. Paraquat was converted to paraquat radical by adding sodium dithionite to tissue homogenates and detected by ESR. Paraquat levels of more than 0.2 micrograms/ml homogenate could be quantified with 0.1 ml of the homogenate. The use of manganese ions for standardization of paraquat signal enabled much more accurate ESR measurements because this ion was quite stable and its signal did not overlap that of paraquat. Even with tissues fixed in formalin, tissues paraquat levels were measureable after removing formalin from the tissue extract. This fact was verified by studying two cases; the tissues were kept in formalin for 1.5 years in case 1 and for 6.5 years in case 2. In both cases, the paraquat contents in tissues were 0.02-0.08 micrograms/g. In this way ESR is one of the most suitable methods in determining low levels of paraquat in tissues even after they were preserved in formalin for a long time.     

肝中对硫磷的固相萃取—电子捕获检测气相色谱分析法

目的建立肝中对硫磷的快速、灵敏、可靠的GC／ECD分析方法。方法肝匀浆加内标甲基对硫磷,用乙腈浸提,浸提液加6％高氯酸稀释,稀释的上清液用GDX403树脂进行固相提取,提取物用HP-5色谱柱和电子捕获检测器进行气相色谱分析。结果提取率92.3％,检测限7.8ng／g,线性范围0.04～4.0μg／g,回收率99.6％±6.2％(Mean±CV,n=5)。结论方法简便、灵敏适合于实际案件检验。     

Detection of drugs using XAD-2 resin. I:Choice of resin, chromatographic conditions, and recovery studies

Amberlite XAD-2, a nonionic polystyrene divinylbenzene resin, was first used for the analysis of drugs in urine and a number of reports have described the development at optimal conditions for extraction, including type of resin columns, pH conditions, and eluting solvents. XAD-4 and XAD-7 resins were compared to the similarly structured XAD-2 resin and no significant advantage over the XAD-2 resin for drug screening was observed. A quantity of 5 to 6 g of resin was found to have sufficient capacity for the extraction of 200 ml of pentobarbital solution (1 mg/100ml). A column flow rate of approximately 15 ml/min (gravitational flow) was sufficient for analysis and slower rates were not more efficient. A mixture of ethyl acetate and 1,2-dichloroethane (3:2) was found to give best overall recovery (66 to 94%) of drugs, the resulting extracts being reasonably free of interfering substances. A pH value of 8.5 is recommended as optimum for comprehensive analysis of acidic and basic drugs. Recovery studies were conducted on spiked samples to determine drug losses occuring during various steps in the XAD-2 extraction procedure for four acidic (amobarbital, secobarbital, pentobarbital, and phenobarbital) and four basic (morphine, codeine, meperidine, and methadone) drugs. A relatively small amount (0 to 5%) of the drugs was not adsorbed by the resin and amounts varying from 6 to 40% failed to be desorbed by the eluting solvent. Additional losses occurred during the removal and analysis of TLC spots. Recovery of drugs from aqueous solutions analyzed with the XAD-2 resin were compared to recoveries reported in the literature with other XAD-2 resin methods for the extraction of drugs from urine. Recovery of phenobarbital, morphine, and codeine improved by 4 to 23% while recoveries of amobarbital, pentobarbital, secobarbital, methadone, and meperidine were 4 to 28% less efficient when compared to literature data.     

Detection of drugs using XAD-2 resin. II:Analysis of liver in medical examiner's cases

Liver tends to concentrate drugs in quantities generally higher than those found in blood or other body compartments. This fact as well as the general availability of liver in postmortem cases makes it an important specimen for comprehensive toxicologic investigation. A scheme for the analysis of liver for drugs with tissue hydrolysis, XAD-2 resin extraction, and TLC has been developed and the parameters affecting recovery have been studied. The hydrolysis of liver specimens at various pH conditions resulted in an improved recovery for morphine by using pH 2 (2N hydrochloric acid). Recoveries of barbiturates, codeine, and meperidine were essentially the same at pH 2 and pH 3. A considerable loss (22 to 55%) was observed for four drugs (pentobarbital, morphine, codeine, and meperidine) as a result of drug binding to the tissue pellets during the process of centrifuging the liver homogenates. This method is recommended as a comprehensive screening procedure for drugs in liver tissue. For quantitative purposes, however, it is necessary to determine a correction factor for all the losses occurring at the various steps of the procedure. This procedure compared favorably with other procedures for liver analysis reported in literature.     

Solid-phase cation exchange extraction of basic drugs from the urine of racing greyhounds

The extraction of basic drugs from the urine of racing greyhounds has been carried out for many years using solvent extraction. This paper describes an extraction method that utilises a cation exchange column. Fourteen basic drugs were introduced onto the column in their ionised form, washed with organic and aqueous solvents and eluted with basic methanol. Three drugs, cyclizine, procaine and quinine were determined in authentic samples from racing greyhounds. A comparison of the solid-phase method with liquid-liquid extraction showed an increase in the efficiency of extraction and a reduction in both the time and cost incurred. The method requires a minimal volume of sample and solvent, little glassware and is easily automated.     

LC／MS／MS法测定生物组织中百草枯

目的建立LC／MS／MS检测生物体液中百草枯方法。方法弱阳离子交换固相萃取小柱提取剂，应用LC／MS／MS法对生物样品中百草枯进行定性定量分析。结果经该方法测得百草枯的最小检出限为10ng／ml血（S／N≥3），线性范围为0．02～20μg／ml。结论该方法快速、灵敏、准确，适用于生物检材中百草枯的分析。     

HPLC法测定百草枯急性中毒大鼠的体内分布

目的 应用高效液相色谱法对口服百草枯急性中毒大鼠体内分布进行测定。方法以200mg／kg剂量百草枯给予Wister大鼠灌胃,4h后脱臼处死,解剖取脑、心、肝、脾、肺、肾、胃、盲肠、肌肉等组织,应用固相萃取法提取,液相色谱法测定各器官组织中百草枯含量。结果各组织经检验,均检出百草枯;组织间百草枯含量（μg／g）相差明显,其中最高为胃（231．47±129．10）,其次为盲肠（87．08±39．86）、肺（22．73±10．20）,最低为心（2．01±0．36）。结论百草枯口服给药后组织分布较为广泛,除胃、肠外各脏器中以肺浓度最高。     

HS-SPME-GC/MS联用法测定生物检材中的百草枯

目的建立检测生物检材中百草枯的顶空固相微萃取-气相色谱-质谱联用（HS-SPME-GC/MS）的分析方法。方法尿样中加乙基百草枯作为内标,在氯化镍作催化剂的条件下,用硼氢化钠在碱性条件下进行还原,HS-SPME萃取,提取物经GC/MS分析。全血需先离心,沉淀血细胞提取上清液,再用甲醇沉淀蛋白。最终得到的上清液加内标乙基百草枯,以下操作同尿样。结果尿样和血样中的百草枯的还原产物在1.0μg/mL~100μg/mL范围内线性关系良好,回归方程分别为y=0.0957x-0.0163,r=0.9974（n=6）;y=0.1096x＋0.0871,r=0.9964（n=6）。尿样、血样低、中、高三个质量浓度,RSD值均小于7%。回收率分别为尿样85.49%~100.83%,血样94.72%~99.68%。结论本法操作简便易行、灵敏度高、快速准确。为检测生物检材中的百草枯提供了有效的方法。     

固相萃取-GC/MS法检测生物检材中的百草枯

目的采用固相萃取-气相色谱/质谱分析方法检测血液、尿液和脏器组织中的百草枯。方法人血液、尿液和猪肺组织样品经三氯乙酸去除蛋白后,取上清用十二烷基三甲基溴化铵和十二烷基硫酸钠处理过的C18小柱提取,提取物用硼氢化钠在碱性条件下还原,产物用气相色谱/质谱法分析,外标法定量。结果生物检材中百草枯回收率为78%～87%,最低检出限为0.1μg/mL,在0.5～1mg/mL范围内线性关系良好,可对实际案例检材进行定量检测。结论本文固相萃取-气相色谱/质谱分析方法能满足中毒生物检材检验及临床毒物检验需要。     

Detection of THCCOOH in hair by MSD-NCI after HPLC clean-up

Regular consumption of cannabis can easily be detected by examination of hair for tetrahydrocannabinol, cannabinol, and cannabidiol. Although several studies have demonstrated that after contamination with smoke or treatment with THC containing shampoos THC is not detectable, or only in small traces, the detection of 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THCCOOH) should be offered to prove the consumption and metabolisation of THC. Up to now this confirmation was only available using tandem MS techniques combined with negative chemical ionisation. A new method using a normal quadrupole GC/MS is described. The lack of expensive instruments has to be paid for by a costly and time consuming extraction and clean-up. After the sample has been digested by 2 M NaOH at 95 degrees C and the neutralised liquid has been extracted with a mixture of n-hexane and ethyl acetate the dried residue is reconstituted in acetonitrile-methanol-0.01 M sulfuric acid (49:21:30, v/v/v) and the cannabinoids separated by HPLC. Each fraction is collected over 1 min. Another extraction with n-hexane-ethyl acetate is followed by evaporation, derivatisation, and GC/MS determination. The calibration with THCCOOH spiked hair led to a LOD of 0.3 pg/mg and a LOQ of 1.1 pg/mg.     

Isolation of drugs from blood and tissues with XAD-2 bags

Nylon bags containing 2-g portions of Amberlite XAD-2 resin were used for systematic analysis of drugs in biosamples. The procedure requires 10 or less grams of material, two XAD-2 bags, and enables rapid and economical isolation of most common drugs. The method was demonstrated on autopsy blood spiked with 19 of the most common drugs, and was routinely used in cases of fatal and non-fatal poisoning. The eluates were clean and suitable for direct gas chromatographic and ultraviolet spectrophotometric analysis.The procedure used appeared more convenient than XAD-2 column extraction procedures. Classic solvent extraction methods were usually less efficient.     

Influence of Paraquat on Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae) Infesting Minced‐beef Substrates in Kelantan,Malaysia

This study investigated the influence of paraquat, a prevalent poison used by suicides, on initial oviposition and development of Chrysomya megacephala (Fabricius) using minced‐beef substrates. Paraquat in lethal dose for human (40 mg/kg), two times the lethal dose (80 mg/kg) and five times the lethal dose (200 mg/kg) were mixed thoroughly with respective minced‐beef substrates (1 kg each) that were decomposed in a shaded habitat fully protected from rain. Results of four replications of the above experiment revealed that the presence of paraquat neither delayed initial oviposition nor prolonged the developmental stages of C. megacephala. Therefore, estimation of postmortem interval (PMI) based on empirical baseline data obtained using animal models devoid of any poisons would still be appropriate for estimating PMI in paraquat‐related deaths.     

高效液相色谱法测定生物体液中百草枯

目的建立HPLC检测生物体液中百草枯方法。方法弱阳离子交换固相萃取小柱提取,水溶性正相液相色谱分析,结合保留时间和紫外光谱对样品中百草枯进行定性。结果经该方法测得百草枯的最小检出限为10ng/m l血(S/N≥3),线性范围为0.1~10μg/ml。结论该方法快速、灵敏、准确,能有效祛除复杂生物基质中杂质干扰,使待测组分获得满意的峰形,适用于生物检材中百草枯的分析。     

Microscopic Residues of Bone from Dissolving Human Remains in Acids

Dissolving bodies is a current method of disposing of human remains and has been practiced throughout the years. During the last decade in the Netherlands, two cases have emerged in which human remains were treated with acid. In the first case, the remains of a cremated body were treated with hydrofluoric acid. In the second case, two complete bodies were dissolved in a mixture of hydrochloric and sulfuric acid. In both cases, a great variety of evidence was collected at the scene of crime, part of which was embedded in resin, polished, and investigated using SEM/EDX. Apart from macroscopic findings like residual bone and artificial teeth, in both cases, distinct microscopic residues of bone were found as follows: (partly) digested bone, thin‐walled structures, and recrystallized calcium phosphate. Although some may believe it is possible to dissolve a body in acid completely, at least some of these microscopic residues will always be found.