Analysis of organophosphorus and pyrethroid pesticides in organic and conventional vegetables using QuEChERS combined with dispersive liquid-liquid microextraction based on the solidification of floating organic droplet.

A simple, sensitive and environmentally-friendly method for determining organophosphorus and pyrethroid pesticides in vegetables was developed to better evaluate the risk of consuming them. The pesticides in vegetables were extracted, purified and concentrated by using the QuEChERS (quick, easy, cheap, effective, rugged and safe method) combined DLLME-SFO (dispersive liquid-liquid microextraction based on solidification of floating organic droplet) techniques. The key parameters were optimized through orthogonal array experimental design and statistical analysis. The linearity of the calibration curves was satisfied in matrix-matched standard solution with R2 ≥ 0.99. The limits of detection and limits of quantification were 0.3-1.5 and 0.9-4.7 µg/kg, respectively. The average recoveries of pesticides were 61.6-119.4% with relative standard deviations <16.1%. Furthermore, the method was applied successfully to analyse the pesticides in 15 pairs of organic and conventional vegetables. These results reflect the efficiency, reliability and robustness of the developed method.

High-Confidence Qualitative Identification of Organophosphorus Nerve Agent Adducts to Human Butyrylcholinesterase.

In this study, a data-dependent, high-resolution tandem mass spectrometry (ddHRMS/MS) method capable of detecting all organophosphorus nerve agent (OPNA) adducts to human butyrylcholinesterase (BChE) was developed. After an exposure event, immunoprecipitation from blood with a BChE-specific antibody and digestion with pepsin produces a nine amino acid peptide containing the OPNA adduct. Signature product ions of this peptic BChE nonapeptide (FGES*AGAAS) offer a route to broadly screen for OPNA exposure. Taking this approach on an HRMS instrument identifies biomarkers, including unknowns, with high mass accuracy. Using a set of pooled human sera exposed to OPNAs as quality control (QC) materials, the developed method successfully identified precursor ions with <1 ppm and tied them to signature product ions with <5 ppm deviation from their chemical formulas. This high mass accuracy data from precursor and product ions, collected over 23 independent immunoprecipitation preparations, established method operating limits. QC data and experiments with 14 synthetic reference peptides indicated that reliable qualitative identification of biomarkers was possible for analytes >15 ng/mL. The developed method was applied to a convenience set of 96 unexposed serum samples and a blinded set of 80 samples treated with OPNAs. OPNA biomarkers were not observed in convenience set samples and no false positive or negative identifications were observed in blinded samples. All biomarkers in the blinded serum set >15 ng/mL were correctly identified. For the first time, this study reports a ddHRMS/MS method capable of complementing existing quantitative methodologies and suitable for identifying exposure to unknown organophosphorus agents.

Nationwide Laboratory Adherence to Myocardial Perfusion Imaging Radiation Dose Reduction Practices: A Report From the Intersocietal Accreditation Commission Data Repository.

OBJECTIVES: This study sought to examine current laboratory practices for radiation effective doses for myocardial perfusion imaging (MPI) and laboratory adherence to guideline-directed radiation reduction practices. BACKGROUND: A recent focus on radiation dose reduction for cardiovascular imaging has led to several published guidelines and consensus statements detailing performance metrics for laboratory practices. We sought to examine laboratory adherence to optimized radiation dose protocol recommendations among 5,216 submitted cases from 1,074 MPI laboratories evaluated for Intersocietal Accreditation Commission accreditation. METHODS: Eligible imaging centers included MPI laboratories enrolled in the Intersocietal Accreditation Commission data repository of accreditation applications from 2012 to 2013. Accreditation requires submission of 3 to 5 cases for evaluation of a range of representative cases. Based on standard dosimetry for rest and stress MPI, an effective dose (in millisieverts) was calculated. Model simulations were performed to estimate guideline-directed effective doses. RESULTS: The average effective dose was 14.9 ± 5.8 mSv (range 1.4 to 42.4 mSv). A 1-day technetium Tc 99m protocol was used in 82.9% of cases, whereas a 2-day technetium Tc 99m and dual isotope protocol was used in 7.5% of submitted cases. Only 1.5% of participating imaging centers met current guidelines for an average laboratory radiation exposure ≤9 mSv, whereas 10.1% of patient effective doses were >20.0 mSv. A model simulation replacing the radiation exposure of dual isotope MPI with that of a 1-day technetium Tc 99m protocol reduced the proportion of patients receiving an effective dose >20 mSv to only 2.7% of cases (p < 0.0001). CONCLUSIONS: Mandatory laboratory accreditation for MPI allows for examination of current radiation dosimetry practices. Current guidelines for reduced patient-specific radiation exposure are rarely implemented, with few laboratories meeting recommendations of ≤9 mSv for 50% of patients. Increased educational efforts and the development of performance measures for laboratory accreditation may be required to meet current radiation dose-reduction standards.

A novel abbreviation standard for organobromine, organochlorine and organophosphorus flame retardants and some characteristics of the chemicals.

Ever since the interest in organic environmental contaminants first emerged 50years ago, there has been a need to present discussion of such chemicals and their transformation products using simple abbreviations so as to avoid the repetitive use of long chemical names. As the number of chemicals of concern has increased, the number of abbreviations has also increased dramatically, sometimes resulting in the use of different abbreviations for the same chemical. In this article, we propose abbreviations for flame retardants (FRs) substituted with bromine or chlorine atoms or including a functional group containing phosphorus, i.e. BFRs, CFRs and PFRs, respectively. Due to the large number of halogenated and organophosphorus FRs, it has become increasingly important to develop a strategy for abbreviating the chemical names of FRs. In this paper, a two step procedure is proposed for deriving practical abbreviations (PRABs) for the chemicals discussed. In the first step, structural abbreviations (STABs) are developed using specific STAB criteria based on the FR structure. However, since several of the derived STABs are complicated and long, we propose instead the use of PRABs. These are, commonly, an extract of the most essential part of the STAB, while also considering abbreviations previously used in the literature. We indicate how these can be used to develop an abbreviation that can be generally accepted by scientists and other professionals involved in FR related work. Tables with PRABs and STABs for BFRs, CFRs and PFRs are presented, including CAS (Chemical Abstract Service) numbers, notes of abbreviations that have been used previously, CA (Chemical Abstract) name, common names and trade names, as well as some fundamental physico-chemical constants.

A rapid radiochemical purity testing method for 99mTc-tetrofosmin.

UNLABELLED: The standard radiochemical purity (RCP) testing method for (99m)Tc-tetrofosmin as described in the package insert requires extensive time (20-30 min) and considerable skill to achieve accurate results. Additionally, the instant thin-layer chromatography strip impregnated with silica gel (2x20 cm) used in the standard method will not be commercially available in the future. The purpose of this study was to evaluate whether a method developed by our laboratory for RCP testing of (99m)Tc-sestamibi could also be used as an alternative method for the RCP assay of (99m)Tc-tetrofosmin. METHODS: The alternative RCP testing system consisted of a precut paper strip (1x8.5 cm) from solvent saturation pads (Pall Corp.) as the stationary phase, with 1:1 chloroform:tetrahydrofuran used as the mobile phase. To validate the reliability of the alternative method, RCP values from 17 kit preparations were compared with the 2 methods. Kits were reconstituted according to the package insert instructions, and 4 additions of (99m)Tc-sodium pertechnetate were purposely added to create trials with RCP values below the accepted limit of 90% purity. RESULTS: Two hundred four trials (100 of which were replicated) were run from the 17 kit preparations. Sixty-four (31%) of the 204 trials were below 90% purity based on the standard method. The overall agreement between the standard and alternative methods was 94% (192/204). The sensitivity of the alternative method for unacceptable RCP limits was 86% (55/64), and the specificity for acceptable RCP values was 98% (137/140). The agreement between the replicated trials of the alternative method was 99% (99/100), and for the standard method it was 92% (92/100). CONCLUSION: The standard method proved to be a much slower method and requires much more precision and attention. The alternative method is much faster, is easier, requires less attention to the solvent-development process, and can be used for RCP testing of both (99m)Tc-tetrofosmin and (99m)Tc-sestamibi. Furthermore, the stationary phase is much more readily available, is not moisture-sensitive, and is less susceptible to operator technique. Our method is accurate in determining the RCP value of (99m)Tc-tetrofosmin and is a better RCP testing method for (99m)Tc-tetrofosmin.

[Chromatographic determination of radiochemical purity - replacement of ITLC SG]. / Chromatographische Bestimmung der radiochemischen Reinheit von Radiopharmaka - Alternativen zu ITLC SG.

UNLABELLED: Thin layer chromatography is well established for quality control of radiopharmaceuticals. A convenient and widely used stationary phase are ITLC SG strips. However, the Pall Corporation stopped manufacturing of the silica gel impregnated glass fibre strips (ITLC SG). Material, Methode: As a replacement we tested silicic acid impregnated glass fibre strips from Varian (ITLC SA) and sufficient mobile phases. RESULTS: The chromatography with these strips takes two to three times longer than with ITLC SG, but it is in an acceptable range. Only three mobile phases are necessary to test most of the common in-house made radiopharmaceuticals. CONCLUSION: The proposed method is suitable for routinely measuring the radiochemical purity of radiophamaceuticals.

Investigation of compound-independent calibration and partial molecular formula determination by gas chromatography-atomic-emission detection for characterisation of organophosphorus and organosulfur agents related to the chemical weapons convention.

Atomic-emission detection (AED) is a technique particularly-well suited to screening complex samples for multiple compounds containing heteroatoms such as phosphorus, sulfur, or nitrogen, which are especially relevant in verification of chemical disarmament. Among other GC detectors, AED has unique characteristics such as compound-independent calibration and possible raw-formula determination. Because contradictory results have been reported on these points, we set up a study with the objectives not only of applying these techniques to chemical weapons convention-related chemicals but of determining under which conditions they would yield satisfactory results. The extensive data collected in this study are evidence that the response of the detector, particularly for the phosphorus line, is very dependent on the molecular mass and concentration of the chemicals analysed whereas molecular structure seems to have less effect on the AED signal. Most interestingly, compound-independent calibration and subsequent partial molecular formula determination usually seem satisfactory when the reference compounds used to calibrate the system have GC retention times and molecular masses close to those of the unknown analytes (whose molecular mass may be determined by GC-CI-MS). We therefore suggest the use of a reference set of compounds covering a large chromatographic window, which enables the selection, within this set, of the most appropriate reference compound for calibration and for determination of the raw formula of an unknown analyte. For optimal performance, the use of a new discharge tube is also recommended.

A better method of quality control for 99mTc-tetrofosmin.

UNLABELLED: The method of quality control (QC) described on the package insert for (99m)Tc-tetrofosmin requires meticulous attention to technique for accurate radiochemical purity results. About 30 min are needed. Other proposed methods have been validated only with pertechnetate. We developed a convenient new method using silica cartridges. METHODS: A silica cartridge with 70:30 methanol:water was determined to be acceptable. The method was validated against sodium pertechnetate ((99m)TcO(4)), (99m)Tc-glucoheptonate, (99m)Tc-sulfur colloid, and low-purity (99m)Tc-tetrofosmin. The validations were made by using a small volume of concentrated (99m)TcO(4) with expired kits. Instant thin-layer chromatography (ITLC) showed 6 impurities after an hour or two. The effects of sample size and flow rate were determined. The precision of repeated tests was determined by comparison with the results of 8 replications on the same batch. The 2 methods were compared at a hospital and at 2 commercial nuclear pharmacies, for a total of 134 replications, with 21 preparations being of <90% radiochemical purity. RESULTS: Volumes between 25 and 100 micro L did not affect the silica-cartridge method but did affect the ITLC method. Flow rate is critical and must be < or =5 mL/min with the silica cartridges. The SD and variance by ITLC were 7 and 51 times larger, respectively. Using the package insert technique as the gold standard, all batches of <90% radiochemical purity were rejected and those of >90% radiochemical purity were accepted. Linear regression gave the following equation: ITLC = 1.0051 x silica cartridge (R = 0.99). One- and 2-binned chi(2) analyses gave P values > 0.999999. A 2 x 2 contingency table showed 100% sensitivity, accuracy, and specificity, with a Fisher's exact test P value of 5.7 x 10(-25). Correlation was nearly perfect. CONCLUSION: According to the published rating criteria for alternate radiochemical purity tests (American Pharmacists' Association), the silica-cartridge method has a score of 90.2, versus 65.8 for ITLC. On the basis of published criteria for alternate radiochemical purity testing methods, the new method is clearly seen to be superior. Furthermore, alternate methods were validated only with free (99m)TcO(4) and colloidal impurities. We showed that these are not the significant radiochemical impurities with (99m)Tc-tetrofosmin and that those methods are not valid. This new method is fast, convenient, accurate, safe, and economical, but careful control of flow rate is required.

Establishment of transfer standard for holmium-166-DOTMP.

The measurement of 166Ho, both as a chloride solution and as [166Ho]-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylenephoonic acid (DOTMP), was examined for four models of radionuclide calibrators: Capintec CRC-35R (two chambers), Capintec 712MX, AtomLab 100 (two chambers), and a Capintec CRC-12. Holmium-166 chloride was measured as 16 ml in 20-ml glass dose vials. Diagnostic imaging level [166Ho]DOTMP solutions, nominally 400 MBqg(-1), were measured as 12 ml in 20-ml dose vials. Finally, therapeutic level [166Ho]DOTMP solutions, nominally 9GBqg(-1), were measured as aliquots of 100-500 microl in sealed plastic vials of 10-ml saline. Single calibration factors for each instrument manufacturer are recommended for 12-16-ml of either solution in 20-ml glass dose vials, (673+/-9) x 10 and 72.7+/-0.7, for the Capintec and AtomLab models, respectively. Calibration factors recommended for the therapeutic dose geometry are (706+/-6) x 10 and 68.7+/-1.3, for the Capintec and AtomLab models, respectively. The calibration factors recommended for an NIST 5-ml ampoule are (686+/-5) x 10 and 70.9+/-0.4 for the Capintec and AtomLab models, respectively.

Rapid quality control for testing the radiochemical purity of 99Tc(m)-tetrofosmin.

We describe a new thin-layer chromatography (TLC) method to evaluate the radiochemical purity of 99Tc(m)-tetrofosmin without the drawbacks of toxicity, solvent ratios and time requirement associated with the standard TLC method. The new method uses miniaturized instant TLC plates impregnated with silica gel (ITLCTM/SG, 2.5 x 10 cm) for the stationary phase and 2-butanone for the mobile phase. The standard TLC method was performed with ITLCTM/SG plates (5 x 20 cm) and dichloromethane/acetone (65:35, v/v). Thirty five preparations were analysed by both methods with a storage phosphor imaging system to determine the percentages of hydrolyzed-reduced 99Tc(m) compound (99Tc(m)O2), 99Tc(m)-tetrofosmin and free 99Tc(m)-pertechnetate (99Tc(m)O4(-)). Using the miniaturized TLC method, 99Tc(m)-tetrofosmin had a mean Rf value of 0.55 (standard deviation, 0.05), while 99Tc(m)O4(-) migrated with the solvent front (Rf=1) and 99Tc(m)O2 remained at the origin of the strips (Rf=0). No significant difference was found between miniaturized and standard TLC methods for the radiochemical purity of 99Tc(m)-tetrofosmin using the Wilcoxon matched-pair signed-rank test (P=0.82). Furthermore, the two methods showed a good correlation as measured by the Spearman rank coefficient (r=0.89) and were in perfect agreement, with a kappa index of +1, for a cut-point between positive and negative set at 90%. In conclusion, the results indicate that the miniaturized TLC method is effective for the routine evaluation of the radiochemical purity of 99Tc(m)-tetrofosmin, without some of the drawbacks of the standard method.

Cidofovir for cytomegalovirus infection and disease in allogeneic stem cell transplant recipients. The Infectious Diseases Working Party of the European Group for Blood and Marrow Transplantation.

A retrospective study was performed to collect information regarding efficacy and toxicity of cidofovir (CDV) in allogeneic stem cell transplant patients. Data were available on 82 patients. The indications for therapy were cytomegalovirus (CMV) disease in 20 patients, primary preemptive therapy in 24 patients, and secondary preemptive therapy in 38 patients. Of the patients, 47 had received previous antiviral therapy with ganciclovir, foscarnet, or both drugs. The dosage of CDV was 1 to 5 mg/kg per week followed by maintenance every other week in some patients. The duration of therapy ranged from 1 to 134 days (median, 22 days). All patients received probenecid and prehydration. Ten of 20 (50%) patients who were treated for CMV disease (9 of 16 with pneumonia) responded to CDV therapy, as did 25 of 38 (66%) patients who had failed or relapsed after previous preemptive therapy and 15 of 24 (62%) patients in whom CDV was used as the primary preemptive therapy. Of the patients, 21 (25.6%) developed renal toxicity that remained after cessation of therapy in 12 patients. Fifteen patients developed other toxicities that were potentially due to CDV or the concomitantly given probenecid. No toxicity was seen in 45 (61.6%) patients. Cidofovir can be considered as second-line therapy in patients with CMV disease failing previous antiviral therapy. However, additional studies are needed before CDV can be recommended for preemptive therapy.

An alternative to the reference method for testing the radiochemical purity of 99Tcm-tetrofosmin.

The recommended method for controlling the radiochemical purity (RCP) of 99Tcm-labelled tetrofosmin is thin-layer chromatography (TLC) with silica gel as the stationary phase and acetone:dichloromethane (35:65, v/v) as the mobile phase. However, this test is time-consuming and uses a toxic substance. We propose an alternative method to control RCP, based on a solid-phase extraction method (SPE) using a Sep Pak C18 cartridge. We used both methods to analyse 35 samples and to determine the percentages of colloid, radiopharmaceutical and free 99Tcm-pertechnetate. Normal labelling processes were modified to obtain a wide range of values. The range of RCP values obtained was 63.4-96.5% (median = 93.8%) by the standard TLC method and 70.1-96.4% (median = 94.1%) by the SPE method. A significant difference was observed only for the percentage of free 99Tcm-pertechnetate (P < 0.05). The agreement between the two methods, using 90% RCP as the limit, gave a kappa index = +1 (P < 0.001), indicating total agreement between them. The proposed method is useful to control RCP because it yields results that are in good agreement with those of the standard method, and because it is safer and less time-consuming.

Artefacts in the thin-layer chromatographic analysis of 99Tcm-tetrofosmin injections.

In an evaluation of techniques for dispensing 99Tcm-tetrofosmin injections, variability in radiochemical purity measured by the recommended 'cut-and-count' thin-layer chromatographic (TLC) analytical technique was observed. This was due to inconsistency in the position of the 99Tcm-tetrofosmin on the chromatography plate. An investigation was therefore undertaken to identify the factors which influence the Rf value of 99Tcm-tetrofosmin and the subsequent effect on the values obtained in the measurement of radiochemical purity. TLC was performed on an ITLC/SG stationary phase with a mobile phase of dichloromethane:acetone (65:35). On a satisfactory chromatogram, the main peak had an Rf of approximately 0.5 and the radiochemical purity was measured at > 90%. The Rf of the main peak and the measured radiochemical purity were found to increase as the size of the sample applied to the plate was increased. Force-drying the sample spot after application to the TLC plate gave a single peak with an Rf of 0. The dimensions of the tank and the time allowed for mobile phase saturation did not affect the outcome of the analysis. Small variations in the composition of the mobile phase affected the Rf of the main peak but not the measured radiochemical purity. TLC plates that were dried at 11 degrees C before use were found to give distorted chromatograms and unreliable measurements of radiochemical purity. In conclusion, when using TLC to measure the radiochemical purity of 99Tcm-tetrofosmin, the following precautions should be observed: (1) the sample spot applied to the TLC plate should be in the range 10-20 microliters; (2) the spot should not be force-dried with air; and (3) ITLC/SG plates should not be dried before use.

[An alternative method to determine the radiochemical purity of the 99mTC-tetrofosmine preparations]. / Un método alternativo para determinar la pureza radioquímica de las preparaciones de 99mTc-Tetrofosmina.

This paper describes a new quality control method to determine the radiochemical purity (RCP) value of Technetium-99m-Tetrofosmin preparations. The results of this procedure were compared with the results obtained with the method suggested by the manufacturer of the kit (classic method), consisting in thin-layer chromatography involving the use of a single strip of ITLC/SG as the stationary phase, and a acetone:dichlorometane 35:65 (Ac:DCM) solvent mixture as the mobile phase. The method that is proposed in this paper (alternative method) uses the same stationary phase but it is developed in a single solvent, methylethylketone (MEK). This method has the following advantages: a better capacity to separate the 99mTc-Tetrofosmin complex from 99mTcO4- and 99mTcO2 impurities, a faster chromatographic developing time and the use of a single solvent in the quality control.

Modified preparation and rapid quality control test for technetium-99m-tetrofosmin.

OBJECTIVE: The objectives of this study were to: modify the preparation of 99mTc-tetrofosmin by using twice the amount of 99mTcO4- recommended by the manufacturer; evaluate the use of miniaturized rapid paper chromatography (MRPC) for quality control (QC) testing; and determine the in vitro stability of the modified preparation using MRPC. METHODS: Two preparations of 99mTc-tetrofosmin were made: one with 4.4-8.8 GBq (120-240 mCi) and the other with 13.9-17.6 GBq (380-480 mCi) 99mTcO4-, referred to as regular and modified preparations, respectively. Routine QC tests were performed using MRPC and instant thin-layer chromatography/silica-gel (ITLC/SG) systems. The preparations were injected into 58 patients. Planar and SPECT images of stress and rest studies were obtained. The technical quality of the SPECT images was graded visually by four observers. Heart-to-lung and heart-to-background ratios were calculated from the planar images. RESULTS: The QC testing procedure took 4.18 +/- 0.15 min with MRPC and 54 +/- 5.3 min with ITLC/SG systems. The percent labeling efficiency, as determined by both techniques, ranged from 95.6 +/- 1.6 to 97.2% +/- 0.8%. Both preparations were stable up to 6 hr after reconstitution. There was no difference between the cardiac-to-lung and cardiac-to-background ratios of the two preparations. CONCLUSION: The results indicate that MRPC is a faster and effective chromatographic technique for routine QC testing of 99mTc-tetrofosmin. Doubling the amount of 99mTcO4- used in preparing 99mTc-tetrofosmin did not affect its in vitro stability, its efficacious use in patients or the technical quality of the images.

[Evaluation of the safety and clinical usefulness of a new myocardial imaging agent, 99mTc-PPN1011--multicenter phase II clinical trial report].

A new myocardial perfusion imaging agent, 99mTc-1,2-bis[bis(2-ethoxyethyl phosphino]ethane (99mTc-PPN1011) was administered to 52 patients with various heart diseases each at rest and peak exercise on different days (Method A) and on the same day (Method B). The safety, optimal dosage, imaging procedures and the clinical usefulness were evaluated. No drug related adverse reactions were found. Image quality was considered adequate for diagnosis with as little as 185 MBq per injection, though the optimal dose range was 370-740 MBq. SPECT images were obtainable as early as 10 min, also until 3 hours after injection. There were no significant differences in clinical efficacy between method A and B, as well as sequential tests at rest and exercise. 99mTc-PPN1011 and 201T1 images in the same patient were compared segment by segment. Image quality of 99mTc-PPN1011 was significantly superior to that of 201T1. Analysis of images indicated that both agent were similar in diagnostic efficacy. It was concluded that 99mTc-PPN1011 is useful for myocardial perfusion imaging.

[Use of the sum of molecular radicals in regression analysis for predicting the toxicity and MPEL of organophosphorus compounds]. / Ispol'zovanie summarnogo vklada radikalov molekuly v uravneniiakh regressii dlia prognozirovaniia toksichnosti i PDK fosfor- organicheskikh soedinenii.

The sum of the organophosphorous compounds' radicals, as calculated with the Free-Wilson technique, provides the most informative descriptor in toximetric indices calculations for these substances in correlation-regression analysis. The resulting formulae can be used in the planning procedures for experimental activities in hygienic standards of these substances and working area MAC's elaboration.

Residuos de plaguicidas fosforados en frutas y hortalizas: estudio preliminar / Organophosphate pesticide residues in fruits and vegetables: preliminary study

Se realizó un estudio de residuos de plaguicidas fosforados en 180 muestras de frutas y hortalizas de consumo interno, encontrando residuos de clorpirifos, bromofos, malatión, etilparatión, fentión como los más frecuentes. El 78% de las muestras presentaron residuos de plaguicidas fosforados. Entre un 10% y 17% de las muestras estuvieron no conformes de acuerdo al Reglamento Sanitario de los Alimentos (5)

1-naphthyl phosphate: specifications for high-quality substrate for measuring prostatic acid phosphatase activity.

Ten lots of sodium 1-naphthyl phosphate were compared by spectrophotometry, high-performance liquid chromatography, and kinetic measurements of the activity of human prostatic acid phosphatase (EC 3.1.3.2) in serum. Two lots were readily identified as the 2-naphthyl phosphate salt by spectrophotometry and liquid chromatography. Four of the remaining eight lots of sodium 1-naphthyl phosphate met the following specifications: (a) sodium 1-naphthyl phosphate content greater than 80% by A286nm measurements (epsilon286nm1-NP = 5630 L.mol-1.cm-1) and by enzymic conversion to 1-naphthol (epsilon332nm1-N = 7560 L.mol-1.cm-1), (b) free 1-naphthol less than 3 mmol/mol, (c) inorganic phosphate less than 10 mmol/mol, and (d) the catalytic activity concentration greater than 98% maximum by absorbance assay and greater than 90% maximum by spectrofluorometric assay during simultaneous comparisons of several substrates. The need for detailed specifications and the testing of each batch of sodium 1-naphthyl phosphate is readily demonstrated by this study.