Rapid and Sensitive ELISA Screening Assay for Several Paralytic Shellfish Toxins in Human Urine.

Paralytic shellfish poisoning is caused by a group of paralytic shellfish toxins that are produced by dinoflagellates. Toxins in this group include saxitoxin, neosaxitoxin and gonyautoxins. A rapid diagnostic test to identify poisoning by these toxins can be helpful in guiding the appropriate treatment of victims. Additionally, quick receipt of diagnostic results can provide timely proof that shellfish harvesting should be stopped in a given area, thereby preventing additional exposures. We have developed and validated a rapid urinary enzyme-linked immunosorbent assay-based screening test to diagnose exposure to several major paralytic shellfish toxins. The lower limit of detection (LLOD) for multiple paralytic shellfish toxins was characterized as 0.02, 0.10, 0.10, 1.0, 1.0 and 15 ng/mL for saxitoxin, gonyautoxin 2,3, decarbamoyl gonyautoxin 2,3, decarbamoyl saxitoxin, neosaxitoxin and gonyautoxin 1,4, respectively. No interferences were identified in unspiked pooled urine or in specimens collected from unexposed individuals indicating that this method is specific for the paralytic shellfish toxins tested. The accuracy of this test was demonstrated in 10 individual urine specimens with osmolalities ranging from 217 to 1,063 mOsmol/kg and pHs ranging between 5.06 and 7.45. These specimens were spiked with toxins at their LLODs and the presence of toxins at these concentrations was accurately identified in all cases. These results indicate that this diagnostic test can be used to rapidly and accurately screen urine for paralytic shellfish toxins.

Biomonitoring of Mycotoxins in Urine: Pilot Study in Mill Workers.

Contamination of grains with mycotoxins results in a dietary background exposure of the general population. In occupational settings such as during processing of raw materials as in milling, an additional mycotoxin exposure by inhalation is possible. Biomonitoring is an integrative approach to assess human exposure from various sources and by all routes. To investigate possible workplace exposure to mycotoxins, a pilot study was conducted that compared levels of urinary biomarkers in mill workers to those in a control group with dietary mycotoxin intake alone. Workers (n = 17) from three grain mills in North Rhine Westphalia, Germany, provided spot urines during shift; volunteers (n = 13, IfADo staff) with matched age structure served as control group. The mycotoxins selected for biomarker analysis were citrinin (CIT) deoxynivalenol (DON), ochratoxin A (OTA), and zearalenone (ZEN). Immunoaffinity columns (CIT, DON, ZEN) or liquid-liquid extraction (OTA) was employed for urine sample cleanup prior to targeted analysis by liquid chromatography with tandem mass spectrometry (LC-MS/MS) or by high-performance liquid chromatography (HPLC). In addition, mycotoxin metabolites that may be formed in the organism were analyzed, including deepoxy-deoxynivalenol (DOM-1), ochratoxin alpha (OTα), dihydrocitrinone (DH-CIT), and α- and ß-zearalenol (α- and ß-ZEL), as well as phase II metabolites that were hydrolyzed with ß-glucuronidase/arylsulfatase prior to sample cleanup. All analyte concentrations were adjusted for creatinine (crea) content in the spot urine samples. Citrinin, DON, OTA, and ZEN were detected in nearly all urine samples from mill workers and controls. Interestingly, DH-CIT was found at higher mean levels than the parent compound (~0.14 and 0.045 µg/g crea, respectively), suggesting an effective metabolism of CIT in humans. Other metabolites DOM-1, OTα, and α- and ß-ZEL were detected less frequently in urine. Deoxynivalenol was detected at the highest concentrations (mean ~6 µg/g crea), followed by OTA (mean ~0.08 µg/g crea); ZEN (mean ~0.03 µg/g crea) and its metabolites appeared in urine at lower levels. Mycotoxin biomarker levels in urine from mill workers and controls were not significantly different. From these results it is concluded that biomarker levels measured in urine samples from the two cohorts reflect mainly dietary mycotoxin exposure. An additional occupational (inhalational) exposure of mill workers, if any, is apparently low at the investigated workplaces.

XRCC1 Arg194Trp and Arg399Gln polymorphisms and arsenic methylation capacity are associated with urothelial carcinoma.

The association between DNA repair gene polymorphisms and bladder cancer has been widely studied. However, few studies have examined the correlation between urothelial carcinoma (UC) and arsenic or its metabolites. The aim of this study was to examine the association between polymorphisms of the DNA repair genes, XRCC1 Arg194Trp, XRCC1 Arg399Gln, XRCC3 Thr241Met, and XPD Lys751Gln, with urinary arsenic profiles and UC. To this end, we conducted a hospital-based case-control study with 324 UC patients and 647 age- and gender-matched non-cancer controls. Genomic DNA was used to examine the genotype of XRCC1 Arg194Trp, XRCC1 Arg399Gln, XRCC3 Thr241Met, and XPD Lys751Gln by PCR-restriction fragment length polymorphism analysis (PCR-RFLP). Urinary arsenic profiles were measured by high performance liquid chromatography (HPLC) linked with hydride generator and atomic absorption spectrometry. The XRCC1 399 Gln/Gln and 194 Arg/Trp and Trp/Trp genotypes were significantly related to UC, and the odds ratio (OR) and 95% confidence interval (95%CI) were 1.68 (1.03-2.75) and 0.66 (0.48-0.90), respectively. Participants with higher total urinary arsenic levels, a higher percentage of inorganic arsenic (InAs%) and a lower percentage of dimethylarsinic acid (DMA%) had a higher OR of UC. Participants carrying XRCC1 risk diplotypes G-C/G-C, A-C/A-C, and A-T/G-T, and who had higher total arsenic levels, higher InAs%, or lower DMA% compared to those with other XRCC1 diplotypes had a higher OR of UC. Our results suggest that the XRCC1 399 Gln/Gln and 194 Arg/Arg DNA repair genes play an important role in poor arsenic methylation capacity, thereby increasing the risk of UC in non-obvious arsenic exposure areas.

Assessment of mycotoxin exposure in the Belgian population using biomarkers: aim, design and methods of the BIOMYCO study.

Mycotoxins are harmful food contaminants. Currently, human exposure assessment to these toxins is often based on calculations combining mycotoxin occurrence data in food with population data on food consumption. Because of limitations inherent to that approach, biomarkers have been proposed as a suitable alternative whereby a more accurate assessment of exposure at the individual level can be performed. The BIOMYCO study is designed to assess human mycotoxin exposure using urinary biomarkers of exposure. Over the different seasons of 2013 and 2014, morning urine is gathered in a representative part of the Belgian population according to a designed study protocol, whereby 140 children (3-12 years old) and 278 adults (19-65 years old) are selected based on random cluster sampling stratified for sex, age and geographical areas. Every participant completes a food frequency questionnaire to assess the consumption of relevant foodstuffs (n = 43) of both the day before the urine collection and the previous month. Validated multi-toxin LC-MS/MS methods are used to analyse aflatoxins, fumonisins, ochratoxin A, trichothecenes, zearalenone and their metabolites in morning urine. The study protocol is approved by the ethical committee of the Ghent University Hospital. Within this paper, study design and methods are described. The BIOMYCO study is the first study whereby a multi-toxin approach is applied for mycotoxin exposure assessment in adults and children on a large scale. Moreover, it is the first study that will describe the exposure to an elaborated set of mycotoxins in the Belgian population. In first instance, descriptive analysis will be performed, describing the exposure to mycotoxins for the child and adult group. Exposure of different subgroups will be compared. Furthermore, correlations between the mycotoxin concentrations measured and the food consumption reported will be estimated to explore whether the mycotoxin exposure could be explained by the consumption of certain foods.

Association between aflatoxin M1 excreted in human urine samples with the consumption of milk and dairy products.

This study aimed to find the association between urinary aflatoxin M(1) level and milk and dairy products consumption. Of 160 morning urine samples collected, aflatoxin M(1) was detected in 61.3 % samples (n = 98) [mean ± SD = 0.0234 ± 0.0177 ng/mL; range = 0-0.0747 ng/mL]. Of these positive samples, 67.3 % (n = 66) had levels above the limit of detection. Respondents with intake of milk and dairy products above median (67.79 g/day) had significantly high level of AFM(1) compared to those with low intake. A significant and positive association (φ = 0.286) was found between milk and dairy products consumption and urinary aflatoxin M(1) level.

Perspectives of liquid chromatography coupled to low- and high-resolution mass spectrometry for screening, identification, and quantification of drugs in clinical and forensic toxicology.

This article reviews papers on the use of liquid chromatography coupled to low- and high-resolution mass spectrometry in clinical and forensic toxicology. They cover procedures for target and for more comprehensive screening for drugs (of abuse), identification of drug metabolites, and multianalyte procedures for quantification of drugs and/or their metabolites in body samples. Besides a critical overview, perspectives are discussed.

Rapid and sensitive determination of strychnine and brucine in human urine by capillary electrophoresis with field-amplified sample stacking.

A simple, rapid, sensitive and low-cost method using capillary electrophoresis (CE) coupled with field-amplified sample stacking (FASS) has been developed and validated for the simultaneous determination of strychnine and brucine residues in human urine. Before sample loading, a water plug (3.5 kPa, 3 s) was injected to contain sample cations and to permit FASS. Electrokinetic injection at a voltage (20 kV, 25 s) was then used to introduce cations. Separation was performed using 20 mM acetate buffer (pH 3.8) with an applied voltage of 20 kV. The calibration curves were linear over a range of 8.00-2.56 infinity 10(2) ng/mL (r = 0.9995) for strychnine and 10.0-3.20 x 10(2) ng/mL (r = 0.9999) for brucine. Extraction recoveries in urine were greater than 79.6 and 82.8% for strychnine and brucine, respectively, with an RSD of less than 4.9%. The detection limits (signal-to-noise ratio 3) for strychnine and brucine were 2.00 and 2.50 ng/mL, respectively. A urine sample from one healthy female volunteer (26 years old, 50 kg) was pretreated and analyzed. Strychnine and brucine levels in urine could be detected 24 h after administration. On these grounds, this method was feasible for application to preliminary screening of trace levels of abused drugs for both doping control and forensic analysis.

[Quantitative determination of strychnine in blood and urine by gas chromatography with mass-selective detector].

A method for the quantitative determination of strychnine in biological fluids by gas chromatography--mass spectrometry is proposed. The preparation of samples for the analysis included extraction of strychnine from blood and urine with the use of AccuBond(II) EVIDEX cartridges for solid-phase extraction and SPEC MP3 disks respectively. The efficiency of extraction was estimated at 0.05 mg/l for blood and 0.02 mg/l for urine. The detection limit was 0.10 mg/l in blood and 0.05 mg/l in urine.

Quantification of saxitoxin and neosaxitoxin in human urine utilizing isotope dilution tandem mass spectrometry.

Saxitoxin and neosaxitoxin are potent neurotoxins that can cause paralytic shellfish poisoning when consumed. A new assay is presented here to quantify saxitoxin (STX) and neosaxitoxin (NEO) in human urine samples. Sample preparation of 500-microL samples included the use of weak-cation-exchange solid-phase extraction in a multiplexed 96-well format. Extracts were preconcentrated and analyzed via 10-min hydrophilic interaction liquid chromatography followed by electrospray ionization. Protonated molecular ions were quantified via multiple reaction monitoring mode in a Qtrap mass spectrometer. The method uses novel 15N7-isotopically enriched STX and NEO internal standards. Method validation included the characterization of two enriched urine pools. The lowest reportable limits for STX and NEO were 4.80 and 10.1 ng/mL, respectively, using both quantification and confirmation ions. These two toxins were not detected in a reference range of humans who consumed seafood in the preceding 72 h, suggesting that few false positives would occur when trying to identify people exposed to STX or NEO.

[High blood and urine concentration of hepatotoxic mycotoxins (aflatoxin B1, sterigmatocystin) in patients with liver cirrhosis]. / Detectarea micotoxinelor hepatotoxice la pacienti cu ciroza Hepatica.

UNLABELLED: Aflatoxins and sterigmatocystin are potent carcinogens, certainly involved in pathogenesis of liver cancer. AIM: To evaluate the risk of mycotoxin intake and to determine the presence of aflatoxin B1 (AFB1) and sterigmatocystin (STC) in patients with liver cirrhosis. MATERIAL AND METHOD: The study included 92 patients (33 controls, 59 liver cirrhosis) that completed a food frequency questionnaire (FFQ). Blood and urine samples were collected and mycotoxins determined by high performance liquid chromatography. RESULTS: 18.18% samples in controls and 72.88% in cirrhosis group presented detectable levels of mycotoxins. The mean values of AFB1 in blood were 0.7 ng/mL in controls and 1.67 ng/mL in test group (p = 0.11); STC presented 60 times higher levels in second group (p < 0.01). AFB1 presented a mean level of 1.2 ng/mL in urine of test group (not detected in controls); STC presented 256 time higher concentration in urine of cirrhotic patients, with a perfect correlation between blood and urine levels in control (r=1) and no correlation in test group (r = 0.05). There were no correlations between mycotoxin, liver enzymes, alpha-fetoprotein and mycotoxin intake risk estimated by FFQ. CONCLUSION: Most of the patients presented detectable levels of mycotoxins, significantly increased in cases with liver cirrhosis, probable due to a specific metabolic pattern.

Urinary biomarkers of aflatoxin exposure in young children from Egypt and Guinea.

Aflatoxins are a major risk factor for hepatocellular carcinoma (HCC), and thus understanding the pattern of aflatoxin exposure in different regions is important in order to develop targeted intervention strategies. Given the early onset of HCC in many countries early life exposures may be important. This study investigated aflatoxin exposure in Egyptian children (n=50, aged 1-2.5 years) by assessing urinary aflatoxin metabolite (AFM(1), AFB(1), AFB(2), AFG(1), AFG(2)) levels. Samples from Guinean children (n=50, aged 2-4 years) were analyzed in parallel providing a comparison to a region of established frequent aflatoxin exposure. Aflatoxins were isolated from urine using C18-cartridges followed by immunoaffinity clean-up, and quantified by HPLC with fluorescence detection. Overall aflatoxins were less frequently present in Egyptian (38%) than Guinean urine samples (86%) (p<0.001), which was particularly related to differences in detection rates of AFM(1) (8% compared to 64%, respectively, (p<0.001)). For AFM(1) the geometric mean level in Guinea (16.3 pg/ml; 95% CI: 10.1, 26.6 pg/ml) was 6-fold higher (p<0.001) than in Egypt (2.7 pg/ml; 95% CI: 2.5, 2.8 pg/ml). Urinary aflatoxins from healthy children in these two regions have not previously been reported, and exposure appears modest in Egypt compared to Guinea. These data suggest that measures to reduce aflatoxin exposure in both regions are important, though particularly in Guinea.

Thio-dimethylarsinate is a common metabolite in urine samples from arsenic-exposed women in Bangladesh.

Over the last 6 years, much work on arsenic species in urine samples has been directed toward the determination of the reduced dimethylated arsenic species, DMA(III), because of its high toxicity and perceived key role in the metabolism of inorganic arsenic. Recent work, however, has suggested that DMA(III) may at times have been misidentified because its chromatographic properties can be similar to those of thio-dimethylarsinate (thio-DMA). We analyzed by HPLC-ICPMS (inductively coupled plasma mass spectrometry) urine samples from 75 arsenic-exposed women from Bangladesh with total arsenic concentrations ranging from 8 to 1034 microg As/L and found that thio-DMA was present in 44% of the samples at concentrations ranging mostly from trace amounts to 24 microg As/L (one sample contained 123 microg As/L). Cytotoxicity testing with HepG2 cells derived from human hepatocarcinoma indicated that thio-DMA was about 10-fold more cytotoxic than dimethylarsinate (DMA). The widespread occurrence of thio-DMA in urine from these arsenic-exposed women suggests that this arsenical may also be present in other urine samples and has so far escaped detection. The work highlights the need for analytical methods providing specific determinations of arsenic compounds in future studies on arsenic metabolism and toxicology.

Bioaccessibility and excretion of arsenic in Niu Huang Jie Du Pian pills.

Traditional Chinese medicines (TCMs) often contain significant levels of potentially toxic elements, including arsenic. Niu Huang Jie Du Pian pills were analyzed to determine the concentration, bioaccessibility (arsenic fraction soluble in the human gastrointestinal system) and chemical form (speciation) of arsenic. Arsenic excretion in urine (including speciation) and facial hair were studied after a one-time ingestion. The pills contained arsenic in the form of realgar, and although the total arsenic that was present in a single pill was high (28 mg), the low bioaccessibility of this form of arsenic predicted that only 4% of it was available for absorption into the bloodstream (1 mg of arsenic per pill). The species of arsenic that were solubilized were inorganic arsenate (As(V)) and arsenite (As(III)) but DMAA and MMAA were detected in urine. Two urinary arsenic excretion peaks were observed: an initial peak several (4-8) hours after ingestion corresponding to the excretion of predominantly As(III), and a larger peak at 14 h corresponding predominantly to DMAA and MMAA. No methylated As(III) species were observed. Facial hair analysis revealed that arsenic concentrations did not increase significantly as a result of the ingestion. Arsenic is incompletely soluble under human gastrointestinal conditions, and is metabolized from the inorganic to organic forms found in urine. Bioaccessible arsenic is comparable to the quantity excreted. Facial hair as a bio-indicator should be further tested.

Urinary arsenic profile affects the risk of urothelial carcinoma even at low arsenic exposure.

Arsenic exposure is associated with an increased risk of urothelial carcinoma (UC). To explore the association between individual risk and urinary arsenic profile in subjects without evident exposure, 177 UC cases and 313 age-matched controls were recruited between September 2002 and May 2004 for a case-control study. Urinary arsenic species including the following three categories, inorganic arsenic (As(III)+As(V)), monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)), were determined with high-performance liquid chromatography-linked hydride generator and atomic absorption spectrometry. Arsenic methylation profile was assessed by percentages of various arsenic species in the sum of the three categories measured. The primary methylation index (PMI) was defined as the ratio between MMA(V) and inorganic arsenic. Secondary methylation index (SMI) was determined as the ratio between DMA(V) and MMA(V). Smoking is associated with a significant risk of UC in a dose-dependent manner. After multivariate adjustment, UC cases had a significantly higher sum of all the urinary species measured, higher percent MMA(V), lower percent DMA(V), higher PMI and lower SMI values compared with controls. Smoking interacts with the urinary arsenic profile in modifying the UC risk. Differential carcinogenic effects of the urinary arsenic profile, however, were seen more prominently in non-smokers than in smokers, suggesting that smoking is not the only major environmental source of arsenic contamination since the UC risk differs in non-smokers. Subjects who have an unfavorable urinary arsenic profile have an increased UC risk even at low exposure levels.

Detection of aflatoxin among hepatocellular carcinoma patients in Egypt.

The present research were tempted to investigate whether Aflatoxin is an additive factor in development of HCC through detecting its metabolite Aflatoxin Ml1 in serum and urine of HCC and cirrhotics in Egypt. Present study comprised (46) Hepatocellular Carcinoma (HCC) patients with mean age (56.28 +/- 8.08), 30 males and 16 females, (12) cirrhotic patients with mean age (47.83 +/- 18.20), 7 males and 5 females and (12) sex and age matched healthy controls. All were exposed to, liver function tests, abdominal ultrasonography and detection of Aflatoxin metabolite M1 in serum and urine by means of the reverse phase HPLC device. Aflatoxin M1 was detected in sera of HCC group, cirrhotics and controls (57.8%) (5.61 +/- 17.21 ng mL(-1)), (91.7%) (19.23 +/- 20.42 ng mL(-1)) and (50%) (0.66 +/- 0.84 ng mL(-1)), respectively and in urine (41.3%) (3.82 +/- 8.03 ng mL(-1)) (91.7%) (43.22 +/- 45.02 ng mL(-1)) and (50%) (0.98 +/- 1.4 ng mL(-1)), respectively representing significant increase in the serum of the cirrhotic group (p < 0.02) and a high significant increase in urine of the cirrhotic group (p < 0.0001). Among HCC group patients, there is high significant value of M1 concentration in urine of upper Egypt residents compared to those of lower Egypt (p < 0.002). The mean value of Aflatoxin M1 concentration among females of the HCC group was significantly higher than that among males (p = 0.006). There is higher statistical significance of aflatoxin prevalence and concentration in serum and urine ofcirrhotics than HCC patients and controls and in concentration in urine of HCC patients from upper than lower Egypt.

Capillary electrophoresis screening of poisonous anions extracted from biological samples.

A method was developed for screening human biological samples for poisonous anions using capillary electrophoresis (CE) employing indirect UV detection. The run buffer consisted of 2.25 mM pyromellitic acid, 1.6 mM triethanolamine, 0.75 mM hexamethonium hydroxide and 6.5mM NaOH at pH 7.7. Biological samples were pretreated using solid phase extraction. The method was applied to the analysis of human blood, plasma, urine, and intestinal contents. Twenty-nine different anions were detectable at aqueous concentrations of 1 part per million (ppm) with a typical analysis time less than 20 min. Intraday migration time R.S.D. and peak area R.S.D. for blood samples were less than 1.1% and 6.3%, respectively. Interday migration time R.S.D. for plasma samples ranged from 7.5% to 10.4%. The new method produced efficient separations of various target anions extracted from complex biological matrices.

Screening for basic drugs in 2-mL urine samples by dual-plate overpressured layer chromatography and comparison with gas chromatography-mass spectrometry.

A dual-plate overpressured layer chromatography (OPLC) method was evaluated for broad-scale screening of basic drugs in 2-mL autopsy urine samples. Extraction was carried out by mixed-mode solid-phase extraction, and identification was based on automated comparison of corrected Rf values (hRfc) and in situ UV spectra with library values by dedicated software. The day-to-day precision of hRfc values was good in both OPLC1 and OPLC2 systems with median relative standard deviations of 2.4% and 3.4%, respectively. Both Rf and hRfc values were independent of the amount of analyte (0.5-10 microg) applied to the plate. Detection limits were determined for 47 drug substances in 2-mL urine samples, and they varied between 0.05 and 3.5 mg/L with a median of 1.0 mg/L. The performance of OPLC was evaluated by analyzing 30 autopsy urine samples by both OPLC and gas chromatography-mass spectrometry (GC-MS). The majority of findings by OPLC were in agreement with GC-MS. Some substances with low concentrations were not detected by OPLC, whereas GC-MS failed to detect a few polar substances. The OPLC method thus provides an alternative for current planar and column liquid chromatographic drug screening methods with the possibility of lowering detection limits by using a larger sample size.

Application of solid-phase micro-extraction technology to drug screening and identification.

Benzodiazepines, tricyclic antidepressants and local anaesthetics are frequently involved in poisoning episodes and fatalities. A specific, sensitive and rapid procedure for identifying and quantifying such drugs in postmortem matrices has been developed using solid-phase micro-extraction (SPME) and gas chromatography-mass spectrometry. Very clean extracts were obtained in one step using SPME. The most commonly used fibre coatings were tested to select the best coating for SPME of the drugs. The appropriate fibre coating for most drugs was polyacrylate, followed by Carbowax-divinylbenzene. A Hewlett-Packard 5890 gas chromatograph in combination with a Trio 2000 mass spectrometer was used to analyse the samples. Temperature, time, pH and addition of sodium chLoride were optimized to obtain consistent extraction. The between-day and within-day coefficients of variation were less than 16% and less than 6%, respectively.

Screening procedure for detection of non-steroidal anti-inflammatory drugs and their metabolites in urine as part of a systematic toxicological analysis procedure for acidic drugs and poisons by gas chromatography-mass spectrometry after extractive methylation.

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used as analgesic and anti-rheumatic drugs, and they are often misused. A gas chromatographic-mass spectrometric (GC-MS) screening procedure was developed for their detection in urine as part of a systematic toxicological analysis procedure for acidic drugs and poisons after extractive methylation. The compounds were separated by capillary GC and identified by computerized MS in the full-scan mode. Using mass chromatography with the ions m/z 119, 135, 139, 152, 165, 229, 244, 266, 272, and 326, the possible presence of NSAIDs and their metabolites could be indicated. The identity of positive signals in such mass chromatograms was confirmed by comparison of the peaks underlying full mass spectra with the reference spectra recorded during this study. This method allowed the detection of therapeutic concentrations of acemetacin, acetaminophen (paracetamol), acetylsalicylic acid, diclofenac, diflunisal, etodolac, fenbufen, fenoprofen, flufenamic acid, flurbiprofen, ibuprofen, indometacin, kebuzone, ketoprofen, lonazolac, meclofenamic acid, mefenamic acid, mofebutazone, naproxen, niflumic acid, phenylbutazone, suxibuzone, tiaprofenic acid, tolfenamic acid, and tolmetin in urine samples. The overall recoveries of the different NSAIDs ranged between 50 and 80% with coefficients of variation of less than 15% (n = 5), and the limits of detection of the different NSAIDs were between 10 and 50 ng/mL (S/N = 3) in the full-scan mode. Extractive methylation has proved to be a versatile method for STA of various acidic drugs, poisons, and their metabolites in urine. It has also successfully been used for plasma analysis.