Confirmation of Syva enzyme multiple immunoassay technique (EMIT) d.a.u. and Roche Abuscreen radioimmunoassay (RIA) (125I) urine cannabinoid immunoassays by gas chromatographic/mass spectrometric (GC/MS) and bonded-phase adsorption/thin-layer chromatographic (BPA-TLC) methods

Thirty human urines screened positive by the Syva enzyme multiple immunoassay technique (EMIT) d.a.u. urine cannabinoid assay were also positive for the major marijuana urinary metabolite 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) when assayed by gas chromatographic/mass spectrometric (GC/MS) and a noninstrumental qualitative bonded-phase adsorption/thin-layer chromatographic (BPA-TLC) technique. The noninstrumental BPA-TLC procedure was the simpler of the two techniques to perform and interpret. Assay of these same samples by the Roche Abuscreen radioimmunoassay (RIA) for cannabinoids (125I) revealed that reliance on the 100-ng/mL equivalent positive calibrator yielded a high incidence of false negative results (10 out of 30). The performance of these same 4 assays on 30 true negatives also was evaluated. All samples were negative for cannabinoids by EMIT and RIA, and for THC-COOH by BPA-TLC. GC/MS assay, however, detected spurious low levels of approximately 5-ng/mL THC-COOH in two instances. Because of this, a reliability level of 10 ng/mL was set for the routine quantitative confirmation of THC-COOH by the GC/MS method.     

Potassium nitrite reaction with 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid in urine in relation to the drug screening analysis.

Recently potassium nitrite has been used as an adulterant to interfere with the analysis of 11-nor-delta 9-tetrahydro-cannabinol-9-carboxylic acid (THC-COOH) in urine. A comprehensive study of the THC-COOH and nitrite reaction chemistry and stability under various conditions is presented. Reverse phase high performance liquid chromatography (HPLC) and negative electrospray mass spectrometry (ESMS) results are given to substantiate the derived reaction mechanism and properties leading to reaction termination. The addition of potassium carbonate as a buffering agent prior to or following sample void as a means of preventing the formation of a nitroso-complexed form of the 11-nor-delta 9+-tetrahydrocannabinol-9-carboxylic acid is evaluated.     

Fast confirmation of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH) in urine by LC/MS/MS using negative atmospheric-pressure chemical ionisation (APCI)

A fast method using automated solid-phase extraction (SPE) and short-column liquid-chromatography coupled to tandem mass-spectrometry (LC/MS/MS) with negative atmospheric-pressure chemical ionisation (APCI) has been developed for the confirmation of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH) in urine samples. This highly specific method which combines chromatographic separation and MS/MS-analysis can be used for the confirmation of positive immunoassay results with a NIDA cut-off of 15ng/ml. The conjugates of THC-COOH were hydrolysed prior to SPE, and a standard SPE was performed using C18-SPE columns. No derivatisation of the extracts was needed as in GC/MS analysis, and the LC run-time was 6.5min by gradient elution with a retention time of 2.4min. Linearity of calibration was obtained in the range between 0 and 500ng/ml (correlation coefficient R(2)=0.998). Using linear regression (0-50ng/ml) the limit of detection (LOD) was 2.0ng/ml and the limit of quantitation (LOQ) was 5.1ng/ml; day-to-day reproducibility and precision were tested at 15 and 250ng/ml and were 13.4ng/ml+/-3.3% and 255.8ng/ml+/-4.5%, respectively.     

Analysis of cannabis in oral fluid specimens by GC-MS with automatic SPE

Methamphetamine (MA) is the most commonly abused drug in Korea, followed by cannabis. Traditionally, MA analysis is carried out on both urine and hair samples and cannabis analysis in urine samples only. Despite the fact that oral fluid has become increasingly popular as an alternative specimen in the field of driving under the influence of drugs (DUID) and work place drug testing, its application has not been expanded to drug analysis in Korea. Oral fluid is easy to collect and handle and can provide an indication of recent drug abuse.In this study, we present an analytical method using GC–MS to determine tetrahydrocannabinol (THC) and its main metabolite 11-nor-Δ⁹-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in oral fluid. The validated method was applied to oral fluid samples collected from drug abuse suspects and the results were compared with those in urine. The stability of THC and THC-COOH in oral fluid stored in different containers was also investigated.Oral fluid specimens from 12 drug abuse suspects, submitted by the police, were collected by direct expectoration. The samples were screened with microplate ELISA. For confirmation they were extracted using automated SPE with mixed-mode cation exchange cartridge, derivatized and analyzed by GC-MS using selective ion monitoring (SIM).The concentrations of THC and THC-COOH in oral fluid showed a large variation and the results from oral fluid and urine samples from cannabis abusers did not show any correlation. Thus, detailed information about time interval between drug use and sample collection is needed to interpret the oral fluid results properly. In addition, further investigation about the detection time window of THC and THC-COOH in oral fluid is required to substitute oral fluid for urine in drug testing.     

Improved gas chromatography-negative ion chemical ionization tandem mass spectrometric method for determination of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in hair using mechanical pulverization and bead-assisted liquid-liquid extraction

A gas chromatography-negative ion chemical ionization tandem mass spectrometric (GC-NCI-MS/MS) method was developed and validated for the determination of 11-nor-Δ(9)-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in human hair. After decontamination, hair samples were weighed (25mg), mechanically pulverized with a bead mill, and incubated in 0.7 mL of 1.0M sodium hydroxide at 95 °C for 30 min. Bead-assisted liquid-liquid extraction was performed with n-hexane:ethyl acetate (9:1, v/v), a method developed in our laboratory. The extract was evaporated to dryness, derivatized with pentafluoropropanol and pentafluoropropionic anhydride, and analyzed by GC-MS/MS in the negative ion chemical ionization mode using methane as the reagent gas. The linear ranges were 0.05-10.0 pg/mg for THC-COOH with the coefficient of determination (r(2) = 0.9976). The intra-day and inter-day precisions were within 1.7 and 13.8%, respectively. The intra-day and inter-day accuracies were -4.8 to 10.0% and -3.9 to 3.8%, respectively. The limit of detection and quantification were 0.015 and 0.05 pg/mg, respectively. The recoveries were in the range of 79.4-87.1%. The results indicate that the proposed method is simple, rapid, accurate, and precise for determination of THC-COOH in hair. The method identified THC-COOH in hair specimens from suspected marijuana abusers.     

Studies on the stability and detection of cocaine, benzoylecgonine, and 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid in whole blood using Abuscreen radioimmunoassay

A study was undertaken to assess the stability and the radioimmunoassay (RIA) detection of cocaine, benzoylecgonine (BZE), and 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in whole blood while stored in 4 different kinds of blood collection tubes for up to 30 days at refrigeration and room temperatures. At various intervals, the tubes were sampled and analyzed using Abuscreen RIA. Also, semi-quantitative data derived from RIA analysis of forensic blood specimens were compared with quantitative data acquired using gas chromatography (GC) or GC/mass spectrometry (GC/MS) on the same specimens. RIA and chromatographic studies revealed that BZE and THC-COOH were stable in blood under all conditions studied. Cocaine, however, was found not to be stable in blood, especially when stored at room temperatures. Despite cocaine's instability in blood, RIA was able to detect the presence of cocaine and its breakdown products in blood under all conditions studied.     

Oral fluid testing for cannabis: on-site OraLine IV s.a.t. device versus GC/MS

Saliva or "oral fluid" has been presented as an alternative matrix to document drug use. The non-invasive collection of a saliva sample, which is relatively easy to perform and can be achieved under close supervision, is one of the most important benefits in a driving under the influence situation. Moreover, the presence of Delta9-tetrahydrocannabinol (THC) in oral fluid is a better indication of recent use than when 11-nor-Delta9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) is detected in urine, so there is a higher probability that the subject is experiencing pharmacological effects at the time of sampling. In the first part of the study, 27 drug addicts were tested for the presence of THC using the OraLine IV s.a.t. device to establish the potential of this new on-site DOA detection technique. In parallel, oral fluid was collected with the Intercept DOA Oral Specimen Collection device and tested for THC by gas chromatography mass spectrometry (GC/MS) after methylation for THC (limit of quantification: 1 ng/mL). The OraLine device correctly identified nine saliva specimens positive for cannabis with THC concentrations ranging from 3 to 265 ng/mL, but remained negative in four other samples where low THC concentrations were detected by GC/MS (1-13 ng/mL). One false positive was noted. Secondly, two male subjects were screened in saliva using the OraLine and Intercept devices after consumption of a single cannabis cigarette containing 25mg of THC. Saliva was first tested with the OraLine device and then collected with the Intercept device for GC/MS confirmation. In one subject, the OraLine on-site test was positive for THC for 2 h following drug intake with THC concentrations decreasing from 196 to 16 ng/mL, while the test remained positive for 1.5 h for the second subject (THC concentrations ranging from 199 to 11 ng/mL). These preliminary results obtained with the OraLine IV s.a.t. device indicate more encouraging data for the detection of THC using on-site tests than previous evaluations.     

LC-MS／MS测定尿液中可卡因及其代谢物苯甲酰爱康宁

目的建立尿液中可卡因(cocaine,COC)及其代谢物苯甲酰爱康宁(benzoylecgonine,BZE)的液相色谱-串联质谱分析方法。方法尿液经固相萃取后,用AllurePFP丙基柱分离,以V(甲醇):V(20mmol/L乙酸胺和0.1%甲酸的缓冲溶液)=80∶20为流动相,采用二级质谱多反应监测模式检测COC和BZE。按10mg/kg的剂量对豚鼠腹腔注射可卡因,给药后收集7d尿液。结果尿液中COC和BZE在2.0～100ng/mL质量浓度范围内线性关系良好(r=0.9995),最低检测限(LOD)为0.5ng/mL;回收率大于90%;日内和日间精密度均小于6%;豚鼠尿液中主要检测目标物是BZE,且BZE检测时限也较COC长。结论所建方法灵敏度高,选择性好,适用于尿液中可卡因和苯甲酰爱康宁的检测。     

Validation of LUCIO-Direct-ELISA kits for the detection of drugs of abuse in urine: application to the new German driving licence re-granting guidelines

LUCIO-Direct-enzyme linked immunosorbent assay (ELISA) tests were validated for the screening of drugs of abuse cannabis, opiates, amphetamines and cocaine in urine for the new German medical and psychological assessment (MPA) guidelines with subsequent gas chromatographic-mass spectrometric (GC-MS) confirmation. The screening cut-offs corresponding to 10 ng/mL 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH), 50 ng/mL amphetamine, 25 ng/mL morphine and codeine and 30 ng/mL benzoylecgonine were chosen at the point where the number of false negatives was lower than 1%. Due to their accuracy, ease of use and rapid analysis, these ELISA tests are very promising for cases where a large proportion of the tests are expected to be negative such as for abstinence monitoring as part of the driving licence re-granting process.     

Validated method for the simultaneous determination of Delta9-THC and Delta9-THC-COOH in oral fluid, urine and whole blood using solid-phase extraction and liquid chromatography-mass spectrometry with electrospray ionization

A fully validated, sensitive and specific method for the extraction and quantification of Delta(9)-tetrahydrocannabinol (THC) and 11-nor-9-carboxy-Delta(9)-THC (THC-COOH) and for the detection of 11-hydroxy-Delta(9)-THC (11-OH THC) in oral fluid, urine and whole blood is presented. Solid-phase extraction and liquid chromatography-mass spectrometry (LC-MS) technique were used, with electrospray ionization. Three ions were monitored for THC and THC-COOH and two for 11-OH THC. The compounds were quantified by selected ion recording of m/z 315.31, 329.18 and 343.16 for THC, 11-OH THC and THC-COOH, respectively, and m/z 318.27 and 346.26 for the deuterated internal standards, THC-d(3) and THC-COOH-d(3), respectively. The method proved to be precise for THC and THC-COOH both in terms of intra-day and inter-day analysis, with intra-day coefficients of variation (CV) less than 6.3, 6.6 and 6.5% for THC in saliva, urine and blood, respectively, and 6.8 and 7.7% for THC-COOH in urine and blood, respectively. Day-to-day CVs were less than 3.5, 4.9 and 11.3% for THC in saliva, urine and blood, respectively, and 6.2 and 6.4% for THC-COOH in urine and blood, respectively. Limits of detection (LOD) were 2 ng/mL for THC in oral fluid and 0.5 ng/mL for THC and THC-COOH and 20 ng/mL for 11-OH THC, in urine and blood. Calibration curves showed a linear relationship for THC and THC-COOH in all samples (r(2)>0.999) within the range investigated. The procedure presented here has high specificity, selectivity and sensitivity. It can be regarded as an alternative method to GC-MS for the confirmation of positive immunoassay test results, and can be used as a suitable analytical tool for the quantification of THC and THC-COOH in oral fluid, urine and/or blood samples.     

Detection of cannabinoids in homicide victims and motor vehicle fatalities

A gas chromatographic/mass spectrometric (GC/MS) procedure is described for the detection and measurement of delta 9-tetrahydrocannabinol, 11-hydroxy-delta 9-tetrahydrocannabinol, and 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid in blood, or 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid in urine. About 50% of all homicide victims and motor vehicle drivers killed in Bexar County in 1985 were tested for the presence of cannabinoids. Of 130 homicides and 69 drivers tested, blood was analyzed primarily in all but 15 and 3 cases, respectively. In these latter cases, blood analyzed after urine was found to be positive. Of the homicide victims, 44 (34%), and of all drivers, 19 (28%), tested were positive for one or more of the cannabinoids. As a separate group, 16 motorcycle drivers tested had 38% positive as compared with 25% of the other vehicle drivers. Ethyl alcohol was present in 55% of the drivers, and in 63% of the homicide victims. Drugs other than alcohol or cannabinoids were found in 10% of the drivers, and in 12% of the homicide victims.     

Significantly increased detection rate of drugs of abuse in urine following the introduction of new German driving licence re-granting guidelines

In this paper we present the first assessment of the new German driving licence re-granting medical and psychological assessment (MPA) guidelines by comparing over 3500 urine samples tested under the old MPA cut-offs to over 5000 samples tested under the new MPA cut-offs. Since the enzyme multiplied immunoassay technique (EMIT) technology used previously was not sensitive enough to screen for drugs at such low concentrations, as suggested by the new MPA guidelines, enzyme-linked immunosorbent assay (ELISA) screening kits were used to screen for the drugs of abuse at the new MPA cut-offs. The above comparison revealed significantly increased detection rates of drug use or exposure during the rehabilitation period as follows: 1.61, 2.33, 3.33, and 7 times higher for 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH), morphine, benzoylecgonine and amphetamine respectively. The present MPA guidelines seem to be more effective to detect non-abstinence from drugs of abuse and hence to detecting drivers who do not yet fulfil the MPA requirements to regain their revoked driving licence.     

Correlations on radioimmunoassay, fluorescence polarization immunoassay, and enzyme immunoassay of cannabis metabolites with gas chromatography/mass spectrometry analysis of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid in urine specimens.

Results obtained from three commercial immunoassay kits, Abuscreen, TDx, and EMIT, commonly used for the initial test of urine cannabinoids (and metabolites) were correlated with the 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (9-THC-COOH) concentration as determined by GC/MS. Correlation coefficients obtained based on 26 (out of 1359 total sample population) highly relevant samples, are 0.601 and 0.438 for Abuscreen and TDx. Correlation coefficients obtained from a parallel study on a different set of 47 (out of 5070 total sample population) highly relevant specimens are 0.658 and 0.575 for Abuscreen and Emit. The immunoassay concentration levels, that correspond to the commonly used 15 ng/ml GC/MS cutoff value for 9-THC-COOH, as calculated from the regression equations are 82 ng/ml and 75 ng/ml for TDx and EMIT and 120 ng/ml and 72 ng/ml for Abuscreen manufactured at two different time periods. The difference of these calculated corresponding concentrations provides quantitative evidence of the reagent specificity differences.     

LC-MS／MS法测定人血浆中盐酸洛哌丁胺

目的建立人血浆中盐酸洛哌丁胺的液相色谱-质谱联用测定法（LC-MS／MS）。方法血浆样品中盐酸洛哌丁胺与盐酸小檗碱（内标）经甲醇液．液提取后,采用ZORBAXSB—C18色谱柱（2．1mm×150mm×5μm）,柱温35℃,流动相为乙腈：0．1％甲酸（60：40,V／V）,流速为0．4mL／min,进样量10μL。电喷雾离子源（ESI）,正离子检测,以多反应监测（MRM）方式进行定量分析,用于监测的离子为m／z477→266（盐酸洛哌丁胺）和m／z366→292（内标）。结果盐酸洛哌丁胺的检测下限为0．2ng／mL（S／N=3）,在浓度0．5～500ng／mL范围内线性良好（r=0．9982）,低、中、高浓度（1ng／mL、20ng／mL、400ng／mL）的平均回收率分别为84．6％,88．5％和90．2％,日内与日问RSD分别小于6％与7％。结论LC—MS／MS法可用于盐酸洛哌丁胺的定性定量分析。     

Detection of amitriptyline, nortriptyline and bromazepam in liver, CSF and hair in the homicidal poisoning of a one-month-old girl autopsied 8 months after death

We reported on the death by poisoning of a one-month-old baby that had followed the death of one of her sister (due to cyamemazine overdose). Exhumation of the corpse was done 8 months after burial and revealed the presence of amitriptyline. Parent drug and its metabolite were analysed by HPLC-MS/MS in positive ionisation mode on a C(18) analytical column using a gradient of acetonitrile and 2mM formate buffer at pH=3. Quantification is based on the main ion m/z=233, the common product ion of nortriptyline (MH(+), m/z 264), amitriptyline (MH(+), m/z 278) and nortriptyline D3 used as internal standard (MH(+), m/z 267). Amitriptyline and nortriptyline in the liver were measured at a concentration of 29.8 and 3.6 μg/g, respectively. Hair analyses revealed the presence of amitriptyline and nortriptyline at concentrations of 1811 and 43 pg/mg, respectively, while complementary analyses showed the presence of bromazepam in the hair at a concentration of 740 pg/mg, thus documenting previous administrations. The mother confessed later having used the drinkable form of the pharmaceutical LAROXYL(?) by pouring the content of a 20 ml bottle (at 40 mg/ml) into the feeding-bottle of her child. The milk was sweet but still bitter and following the testimony of a close relative, the whole family helped to feed the crying baby.     

A research note: the outcome of GC/MS/MS confirmation of hair assays on 93 cannabinoid (+) cases

This article reports the outcome of gas chromatography/tandem mass spectrometry confirmations for THC and carboxy-THC on 93 hair samples screened by RIA for cannabinoids. The samples were taken from probationers in Pinellas County, FL, who voluntarily provided the research staff with six hair and six urine specimens, collected at 1-month intervals. There were 40 samples that were RIA (+), urinalysis (−). Samples were selected which had cannabinoid (+) outcomes for hair, urine, or both. The THC and/or the carboxy-THC was (+) on confirmation. Of these 40 samples, 22 were (+) for both THC and carboxy-THC, 15 were (+) for THC but not carboxy-THC, and three were carboxy THC (+), but THC (−). Only one sample had a (+) RIA, but was (−) for both THC and carboxy-THC on confirmation. RIA detection of cannabinoids was confirmed in nearly all cases. Most cases that were RIA (−) but urine (+) were cannabinoid (+) when analyzed by GC/MS/MS.     

LC-MS/MS分析人全血中五氟利多

目的建立人体全血中五氟利多浓度的液相色谱-质谱联用法（LC-MS/MS）分析方法。方法全血中五氟利多和利培酮（内标）经正己烷液-液提取后,采用Capcell Pak C18色谱柱（250mm×2.0mm5,μm）进行分离,流动相为乙腈：20mmol/L乙酸胺和0.1%甲酸溶液（75∶25,V/V）,流速为0.2mL/min,然后以MS/MS电喷雾正电离的多反应监测扫描方式（MRM）测定。用于定量分析的离子为m/z 524→109（五氟利多）和m/z 411→191（内标）。结果五氟利多的最低检测限为0.2ng/mL,在0.4～400ng/mL浓度范围内线性良好（r=0.9994）,低、中、高浓度（1ng/mL、10ng/mL、100ng/mL）准确度分别为97%,108%和95%,日内和日间RSD均小于15%。结论该方法简便、快速、灵敏,适用于全血中五氟利多浓度的测定。     

Two fatal intoxication cases with imidacloprid: LC/MS analysis

Imidacloprid [1-(6-chloro-3pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] is a new and potent nitromethylene insecticide with high insecticidal activity at very low application rates. It is the first highly effective insecticide that, like nicotine, acts on the nervous system, causing blockage of postsynaptic nicotinergic acetylcholine receptors. Two fatal cases with this insecticide in two male individuals, of 33 and 66 years old, are presented. An LC/MS with electrospray method for measuring imidacloprid and its metabolites in post-mortem samples is described. In the chromatographic separation, a reverse-phase column XTerra MS C18 (2.1mm i.d.x 150 mm, 5 microm) was used and the mobile phase composed with acetonitrile and 0.1% formic acid (15:85), at a 0.25 mL/min flow rate. Samples were prepared with a liquid-liquid extraction procedure with dichloromethane. Calibration curves for imidacloprid in blood and urine samples were linear from 0.2 to 15 microg/mL. The mean recovery was 86% with a coefficient of variation of +/-5.9%. The detection limit was 0.002 microg/mL. Quantitative results were obtained for all post-mortem matrices available of the two fatal cases: blood, urine, stomach contents, lung, liver and kidney. The imidacloprid blood concentrations found in two-cases were 12.5 and 2.05 microg/mL. The authors validated a method to detect and quantify imidacloprid in post-mortem samples, and to our knowledge for the first time a post-mortem tissue distribution was performed on various samples for this insecticide.     

Partition coefficient, blood to plasma ratio, protein binding and short-term stability of 11-nor-Delta(9)-carboxy tetrahydrocannabinol glucuronide

11-Nor-Delta(9)-carboxy tetrahydrocannabinol glucuronide (THCCOOglu) is a major metabolite of tetrahydrocannabinol in blood. Despite its mass spectrometric identification already in 1980, further physicochemical data of THCCOOglu have not been established. Therefore, the octanol/buffer partition coefficient P and the blood to plasma ratio b/p for THCCOOglu concentrations of 100 and 500ng/ml were investigated. Protein binding of the glucuronide was established from spiked albumin solutions at a level of 250ng/ml as well as from authentic samples. The data were compared to those of 11-nor-Delta(9)-carboxy tetrahydrocannabinol (THCCOOH). In addition, the short-term stability of THCCOOglu in plasma at different storage temperatures was studied. Analysis was performed by LC/MS/MS. The glucuronide partition coefficient P (mean: 17.4 and 18.0 for 100 and 500ng/ml, respectively) was unexpectedly lipophilic at pH 7.4. Its blood to plasma ratios averaged 0.62 and 0.68 at 100 and 500ng/ml, respectively. THCCOOglu was highly reversibly bound to albumin (mean: 97%), and the mean fraction bound did not differ from that determined from authentic samples. THCCOOglu degraded even at a storage temperature of 4 degrees C and THCCOOH was identified as a major decomposition product.     

Comparison of Abbott fluorescence polarization immunoassay (FPIA) and Roche radioimmunoassay for the analyses of cannabinoids in urine specimens.

Abbott fluorescence polarization immunoassay (FPIA) and Roche Abuscreen radioimmunoassay (RIA) were compared qualitatively with 142 urine specimens containing 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid. Similar qualitative results were obtained in 132 specimens. When discrepent results were observed, all negative results were within 20% of the 100 ng/mL cut-off. We concluded that FPIA and RIA give comparable results to each other.