Page:NIOSH Manual of Analytical Methods - 8301.pdf/4

 HIPPURIC and METHYL HIPPURIC ACIDS in urine: METHOD 8301, Issue 3, dated 15 March 2003 - page 4 of 5 EVALUATION OF METHOD: LOD/LOQ studies were p erform ed u sing standard s in synthetic u rine, standards in pooled urine, and standards in water. Standards dissolved in synthetic urine gave LODs of 4 µg/mL, 5 µg/mL, 6 µg/mL for hippuric acid, 2-methyl hippuric acid, 3-methyl hippuric acid, and 4-m eth yl hippuric acid, respectively. W ater proved to be a poor m atrix for hippuric acids, giving a high variability. Pooled urine also gave a high variability due to an initial background. Endogenous hippuric acids in pooled urine will skew the calibration curve. Reco very study data shows greater than 96% overall recovery for all analytes from spiked synthetic urine. Overall recovery rates were slightly lower (93% ) for spike d po oled urine, possibly due to variability in natu rally occurring hippuric acids. Precision, Accuracy, and Bias data (Table 1) were obtained for synthetic urine using 7 replica tes at 6 different c onc entra tion leve ls from 10 µ g/m L to 1000 µg/L. Results using pooled urine were similar. A 30-day stability study showed that the hippuric acids in synthetic urine were stable for 7 days at 22 oC and 30 days at 4 oC. In a single synthetic urine sample, hippuric acid was stable through temperature changes from -20 oC to 30oC for 24 hours. Sonication did not affect hippuric acid stability in the samples.

REFERENCES: [1] Mo tok GT, Perk ins JB, R eynolds JM [2002 ]. Hippuric and m ethyl hipp uric acids in urine, back up da ta report. Salt Lake City, Utah: DataChem Laboratories, Inc. [2] Pa cific T oxicology Laboratories [2003]. Hum an tox ic chem ical exposure, The Bulletin of P acific To xicology Labora tories, www.pa ctox .com /toluen e.htm. [3] Matsui H, Kasao M, Imam ura S [1978]. High performance liquid chromatographic determination of hippuric acid in hum an u rine, J. Chrom atog ., 45:231. [4] So llenberg J and Baldeste n A [1977]. Isota chophoretic analysis of m andelic acid, phenylglyoxylic acid, and/or xylen e, J. C hrom atog ., 132:469. [5] Ta rdif R and Brodeu r J [19 85]. J. Ana l. Tox ., 13:313. [6] Tietz NW [1976]. Funda m enta ls of C linical Ch em istry, 2 nd ed., pp. 994-999, W .B. Sa und ers Co., Philadelphia, PA. [7] Lauwerys RR [1996]. Industrial chemical exposure: guidelines for biological monitoring. Davis, CA: Biomedical Publications, pp. 57-69. [8] Phipps F [1994]. Hippuric and methyl hippuric acids in urine, Method 8301, Issue 2. In: Eller PM, Ca ssinelli ME, eds. NIO SH Ma nua l of Analytical Metho ds, 4 th edition. Cincinnati, OH: Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health. DHHS (NIOSH) Publication No. 94-113. [9] UK [2003]. UK Government Information Notes on the Diagnosis of Prescribed Diseases. Conditions due to chem ical agent, www.m app erleyplains.co.uk /opru s/be nzen es.h tm.

METHOD UPDATED BY: George T. Motock, James B. Perkins, and John M. Reynolds, DataChem Laboratories, Inc., Salt Lake City, Utah 84123, under NIOSH contract CDC-200-2001-08000. Previous Issues Frederick C. Phipps, NIOSH/DBBS

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition