Comparison of Colorimetric and HPLC Methods for Determination of .DELTA.-Aminolevulinic Acid in Urine with Reference to Dose-Response Relationship in Occupational Exposure to Lead

Abstract

Both traditional colorimetry and recently developed HPLC-fluorometry have been in use for determination of δ δ δ δ δ-aminolevulinic acid in urine (ALA-U), an effect marker of occupational exposure to lead (Pb). The present study was initiated to compare the values by the two methods on an epidemiology basis among workers occupationally exposed to lead (Pb), to estimate quantitatively the colorimetry-associated increment over the values by the HPLC method, to evaluate ALA-U determination in occupational health service for Pb-exposed workers, and to identify a critical Pb-B to induce an elevation in ALA-U. For this purpose, blood and urine samples were collected from three groups of Pb-exposed workers (both men and women in combination, including smokers) and analyzed for Pb in blood (Pb-B; measured in all subjects) and ALA-U (by colorimetry or HPLC), i.e., Group 1 (164 subjects with urinalysis by the two methods), Group 2 (2,923 subjects by colorimetry), and Group 3 (2,540 subjects by HPLC). ALA-U when measured by colorimetry was higher than the values by HPLC, and that the mean difference on a group basis was 1.4 mg/l (in a range of 1.1 to 1.8 mg/l), irrespective of Pb-B levels. It was also found that the increase in ALA-U was small when Pb-B was relatively low (e.g., ≤40 µg/100 ml), and that the increase on a group basis in response to an increase in Pb-B from 5 to 40 µg/100 ml was as small as ≤0.6 mg/l. Thus, ALA-U appeared to be not a sensitive marker of Pb effects at low Pb-B levels. ALA-U however increased substantially with a point of inflection at the Pb-B level of about 17-34 µg/100 ml. Thus it was concluded that ALA-U as measured by colorimetry is greater than ALA-U by HPLC by 1.4 mg/l on average irrespective of intensity of Pb-exposure, which may induce bias in evaluation of health effect, and that ALA-U levels will increase when Pb-B is in excess of 17-34 µg/100 ml.

Potential of biofertilizers from selected Rhodopseudomonas palustris strains to assist rice (Oryza sativa L. subsp. indica) growth under salt stress and to reduce greenhouse gas emissions

“…The maximum ALA contents at day 9 of TK103, PP803, and P1 biofertilizers were 2.25, 2.61, and 1.64 μM. Our results are supported by Fukui et al (2005) who reported that ALA in urine as measured by colorimetric method is greater than ALA in urine by HPLC method.…”

Improvement of an HPLC method to determine urinary δ-aminolevulinic acid

“…The advantages of using HPLC methodology has been extensively reported in the literature (7) . Colorimetric methods that also measure (ANVISA) (10) , Foods and Drugs Administration (FDA) (6) and Clinical and Laboratory Standards Institute (CLSI) (2) guidelines were followed.…”

“…Although colorimetric methods are used to quantify ALA-U, the sensibility and specificity of chromatographic methods with fluorescence detection are well known (7) . Analytical methods that can detect slight alterations of ALA-U are crucial for preventive actions in cases where metabolic alterations are still reversible (1) .…”

Practical Considerations in the Pharmaceutical Analysis of Methyl and Hexyl Ester Derivatives of 5-Aminolevulinic Acid

“…For example, serum ALA levels are elevated in lead poisoning, hereditary tyrosinema and the acute porphyrias. Consequently, a number of groups have reported methods for ALA determination in biological samples [32,33]. More recently, ALA has been applied topically for the diagnosis and treatment of premalignant and malignant skin lesions.…”